MICROCHIP PIC18F45K20-I/MV

PIC18F23K20/24K20/25K20/26K20/
43K20/44K20/45K20/46K20
Data Sheet
28/40/44-Pin Flash Microcontrollers
with nanoWatt XLP Technology
 2010 Microchip Technology Inc.
DS41303G
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE. Microchip disclaims all liability
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, dsPIC,
KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART,
rfPIC and UNI/O are registered trademarks of Microchip
Technology Incorporated in the U.S.A. and other countries.
FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor,
MXDEV, MXLAB, SEEVAL and The Embedded Control
Solutions Company are registered trademarks of Microchip
Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, CodeGuard,
dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN,
ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial
Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified
logo, MPLIB, MPLINK, mTouch, Octopus, Omniscient Code
Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit,
PICtail, PIC32 logo, REAL ICE, rfLAB, Select Mode, Total
Endurance, TSHARC, UniWinDriver, WiperLock and ZENA
are trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2010, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
DS41303G-page 2
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
28/40/44-Pin Flash Microcontrollers
with nanoWatt XLP Technology
High-Performance RISC CPU:
• C Compiler Optimized Architecture:
- Optional extended instruction set designed to
optimize re-entrant code
• Up to 1024 bytes Data EEPROM
• Up to 64 Kbytes Linear Program Memory
Addressing
• Up to 3936 bytes Linear Data Memory Addressing
• Up to 16 MIPS Operation
• 16-bit Wide Instructions, 8-bit Wide Data Path
• Priority Levels for Interrupts
• 31-Level, Software Accessible Hardware Stack
• 8 x 8 Single-Cycle Hardware Multiplier
Flexible Oscillator Structure:
• Precision 16 MHz Internal Oscillator Block:
- Factory calibrated to ± 1%
- Software selectable frequencies range of
31 kHz to 16 MHz
- 64 MHz performance available using PLL –
no external components required
• Four Crystal modes up to 64 MHz
• Two External Clock modes up to 64 MHz
• 4X Phase Lock Loop (PLL)
• Secondary Oscillator using Timer1 @ 32 kHz
• Fail-Safe Clock Monitor:
- Allows for safe shutdown if peripheral clock
stops
- Two-Speed Oscillator Start-up
Special Microcontroller Features:
• Operating Voltage Range: 1.8V to 3.6V
• Self-Programmable under Software Control
• Programmable 16-Level High/Low-Voltage
Detection (HLVD) module:
- Interrupt on High/Low-Voltage Detection
• Programmable Brown-out Reset (BOR):
- With software enable option
• Extended Watchdog Timer (WDT):
- Programmable period from 4 ms to 131s
• Single-Supply 3V In-Circuit Serial
Programming™ (ICSP™) via Two Pins
• In-Circuit Debug (ICD) via Two Pins
 2010 Microchip Technology Inc.
Extreme Low-Power Management
with nanoWatt XLP:
• Sleep mode: < 100 nA @ 1.8V
• Watchdog Timer: < 800 nA @ 1.8V
• Timer1 Oscillator: < 800 nA @ 32 kHz and 1.8V
Analog Features:
• Analog-to-Digital Converter (ADC) module:
- 10-bit resolution, 13 External Channels
- Auto-acquisition capability
- Conversion available during Sleep
- 1.2V Fixed Voltage Reference (FVR) channel
- Independent input multiplexing
• Analog Comparator module:
- Two rail-to-rail analog comparators
- Independent input multiplexing
• Voltage Reference (CVREF) module
- Programmable (% VDD), 16 steps
- Two 16-level voltage ranges using VREF pins
Peripheral Highlights:
• Up to 35 I/O Pins plus 1 Input-only Pin:
- High-Current Sink/Source 25 mA/25 mA
- Three programmable external interrupts
- Four programmable interrupt-on-change
- Eight programmable weak pull-ups
- Programmable slew rate
• Capture/Compare/PWM (CCP) module
• Enhanced CCP (ECCP) module:
- One, two or four PWM outputs
- Selectable polarity
- Programmable dead time
- Auto-Shutdown and Auto-Restart
• Master Synchronous Serial Port (MSSP) module
- 3-wire SPI (supports all 4 modes)
- I2C™ Master and Slave modes with address
mask
• Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) module:
- Supports RS-485, RS-232 and LIN
- RS-232 operation using internal oscillator
- Auto-Wake-up on Break
- Auto-Baud Detect
DS41303G-page 3
PIC18F2XK20/4XK20
Program Memory
Device
Data Memory
(1)
Flash # Single-Word SRAM EEPROM I/O
(bytes) Instructions (bytes) (bytes)
10-bit
A/D
(ch)(2)
CCP/
ECCP
(PWM)
MSSP
SPI
Master
I2C™
EUSART
-
Comp.
Timers
8/16-bit
PIC18F23K20
8K
4096
512
256
25
11
1/1
Y
Y
1
2
1/3
PIC18F24K20
16K
8192
768
256
25
11
1/1
Y
Y
1
2
1/3
PIC18F25K20
32K
16384
1536
256
25
11
1/1
Y
Y
1
2
1/3
PIC18F26K20
64k
32768
3936
1024
25
11
1/1
Y
Y
1
2
1/3
PIC18F43K20
8K
4096
512
256
36
14
1/1
Y
Y
1
2
1/3
PIC18F44K20
16K
8192
768
256
36
14
1/1
Y
Y
1
2
1/3
PIC18F45K20
32K
16384
1536
256
36
14
PIC18F46K20
64k
32768
3936
1024
36
14
Note 1: One pin is input only.
2: Channel count includes internal fixed voltage reference channel.
DS41303G-page 4
1/1
Y
Y
1
2
1/3
1/1
Y
Y
1
2
1/3
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
Pin Diagrams
28-pin PDIP, SOIC, SSOP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
RA1/AN1/C12IN1RA0/AN0/C12IN0-
MCLR/VPP/RE3
RA0/AN0/C12IN0RA1/AN1/C12IN1RA2/AN2/VREF-/CVREF/C2IN+
RA3/AN3/VREF+/C1IN+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
RE0/RD/AN5
RE1/WR/AN6
RE2/CS/AN7
VDD
VSS
OSC1/CLKIN/RA7
OSC2/CLKOUT/RA6
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1/P1A
RC3/SCK/SCL
RD0/PSP0
RD1/PSP1
PIC18F43K20
PIC18F44K20
PIC18F45K20
PIC18F46K20
40-pin PDIP
28-pin QFN/UQFN(2)
28
27
26
25
24
23
22
21
20
19
18
17
16
15
PIC18F23K20
PIC18F24K20
PIC18F25K20
PIC18F26K20
1
2
3
4
5
6
7
8
9
10
11
12
13
14
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
RB7/KBI3/PGD
RB6//KBI2/PGC
RB5/KBI1/PGM
RB4/KBI0/AN11/P1D
RB3/AN9/C12IN2-/CCP2(1)
RB2/INT2/AN8/P1B
RB1/INT1/AN10/C12IN3-/P1C
RB0/INT0/FLT0/AN12
VDD
VSS
RC7/RX/DT
RC6/TX/CK
RC5/SDO
RC4/SDI/SDA
RB7/KBI3/PGD
RB6/KBI2/PGC
RB5/KBI1/PGM
RB4/KBI0/AN11
RB3/AN9/C12IN2-/CCP2(1)
RB2/INT2/AN8
RB1/INT1/AN10/C12IN3RB0/INT0/FLT0/AN12
VDD
VSS
RD7/PSP7/P1D
RD6/PSP6/P1C
RD5/PSP5/P1B
RD4/PSP4
RC7/RX/DT
RC6/TX/CK
RC5/SDO
RC4/SDI/SDA
RD3/PSP3
RD2/PSP2
MCLR/VPP/RE3
RB7/KBI3/PGD
RB6/KBI2/PGC
RB5/KBI1/PGM
RB4/KBI0/AN11/P1D
MCLR/VPP/RE3
RA0/AN0/C12IN0RA1/AN1/C12IN1RA2/AN2/VREF-/CVREF/C2IN+
RA3/AN3/VREF+/C1IN+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
VSS
OSC1/CLKIN/RA7
OSC2/CLKOUT/RA6
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1/P1A
RC3/SCK/SCL
28 27 26 25 24 23 22
RA2/AN2/VREF-/CVREF/C2IN+
RA3/AN3/VREF+/C1IN+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
VSS
OSC1/CLKIN/RA7
OSC2/CLKOUT/RA6
1
2
3
4
5
6
7
PIC18F23K20
PIC18F24K20
PIC18F25K20
PIC18F26K20
21
20
19
18
17
16
15
RB3/AN9/C12IN2-/CCP2(1)
RB2/INT2/AN8/P1B
RB1/INT1/AN10/C12IN3-/P1C
RB0/INT0/FLT0/AN12
VDD
VSS
RC7/RX/DT
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1/P1A
RC3/SCK/SCL
RC4/SDI/SDA
RC5/SDO
RC6/TX/CK
8 9 10 11 12 13 14
Note
1:
RB3 is the alternate pin for CCP2 multiplexing.
2:
UQFN package availability applies only to PIC18F23K20.
 2010 Microchip Technology Inc.
DS41303G-page 5
PIC18F2XK20/4XK20
RC6/TX/CK
RC5/SDO
RC4/SDI/SDA
RD3/PSP3
RD2/PSP2
RD1/PSP1
RD0/PSP0
RC3/SCK/SCL
RC2/CCP1/P1A
RC1/T1OSI/CCP2(1)
NC
Pin Diagrams (Cont.’d)
44
43
42
41
40
39
38
37
36
35
34
44-pin TQFP
12
13
14
15
16
17
18
19
20
21
22
PIC18F43K20
PIC18F44K20
PIC18F45K20
PIC18F46K20
NC
RC0/T1OSO/T13CKI
OSC2/CLKOUT/RA6
OSC1/CLKIN/RA7
VSS
VDD
RE2/CS/AN7
RE1/WR/AN6
RE0/RD/AN5
RA5/AN4/SS/HLVDIN/C2OUT
RA4/T0CKI/C1OUT
33
32
31
30
29
28
27
26
25
24
23
44
43
42
41
40
39
38
37
36
35
34
44-pin QFN
1
2
3
4
5
6
7
8
9
10
11
NC
NC
RC6/TX/CK
RB4/KBI0/AN11
RC5/SDO
RB5/KBI1/PGM
RC4/SDI/SDA
RB6/KBI2/PGC
RD3/PSP3
RB7/KBI3/PGD
RD2/PSP2
MCLR/VPP/RE3
RD1/PSP1
RA0/AN0/C12IN0RD0/PSP0
RA1/AN1/C12IN1RC3/SCK/SCL
RA2/AN2/VREF-/CVREF/C2IN+
RC2/CCP1/P1A
RA3/AN3/VREF+/C1IN+
RC1/T1OSI/CCP2(1)
RC0/T1OSO/T13CKI
RC7/RX/DT
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
VSS
VDD
RB0/INT0/FLT0/AN12
RB1/INT1/AN10/C12IN3RB2/INT2/AN8
RB3/AN9/C12IN2-/CCP2(1)
Note
1:
RB3 is the alternate pin for CCP2 multiplexing.
DS41303G-page 6
PIC18F43K20
PIC18F44K20
PIC18F45K20
PIC18F46K20
33
32
31
30
29
28
27
26
25
24
23
12
13
14
15
16
17
18
19
20
21
22
1
2
3
4
5
6
7
8
9
10
11
OSC2/CLKOUT/RA6
OSC1/CLKIN/RA7
VSS
VSS
VDD
VDD
RE2/CS/AN7
RE1/WR/AN6
RE0/RD/AN5
RA5/AN4/SS/HLVDIN/C2OUT
RA4/T0CKI/C1OUT
RB3/AN9/C12IN2-/CCP2(1)
NC
RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
MCLR/VPP/RE3
RA0/AN0/C12IN0RA1/AN1/C12IN1RA2/AN2/VREF-/CVREF/C2IN+
RA3/AN3/VREF+/C1IN+
RC7/RX/DT
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
VSS
VDD
VDD
RB0/INT0/FLT0/AN12
RB1/INT1/AN10/C12IN3RB2/INT2/AN8
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
RA2
AN2
C2IN+
VREF-/
CVREF
5
22
22
RA3
AN3
6
23
23
RA4
C1IN+
VREF+
C1OUT
—
DIL Pin
Basic
21
Pull-up
21
Interrupts
4
Slave
—
—
Timers
C12IN1-
MSSP
C12IN0-
AN1
EUSART
AN0
RA1
ECCP
RA0
20
Analog
19
20
I/O
19
3
QFN Pin
2
TQFP Pin
Reference
PIC18F4XK20 PIN SUMMARY
Comparator
TABLE 1:
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
T0CKI
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
T1OSI
—
7
24
24
RA5
AN4
C2OUT
HLVDIN
14
31
33
RA6
—
—
—
13
30
32
RA7
—
33
8
9
RB0
AN12
—
—
34
9
10
RB1
AN10
C12IN3-
35
10
11
RB2
AN8
—
36
11
12
RB3
AN9
C12IN2-
37
14
14
RB4
AN11
38
15
15
RB5
39
16
16
RB6
40
17
17
RB7
15
32
34
RC0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
16
35
35
RC1
36
36
RC2
—
—
—
—
—
—
CCP2(2)
17
18
37
37
RC3
—
—
—
—
—
SCK/
SCL
23
42
42
RC4
—
—
—
—
—
24
43
43
RC5
25
44
44
RC6
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
26
1
1
RC7
19
38
38
RD0
20
39
39
RD1
21
40
40
RD2
22
41
41
RD3
27
2
2
RD4
28
3
3
RD5
29
4
4
RD6
30
5
5
RD7
—
—
—
—
—
—
—
—
—
—
—
8
25
25
RE0
AN5
9
26
26
RE1
AN6
10
27
27
RE2
AN7
1
18
18
RE3(3)
11
7
7
32
28
28
12
6
6
31
29
30
–
NC
8
–
NC
29
–-
NC
31
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Note 1:
2:
3:
FLT0
—
—
CCP2(1)
—
—
—
—
—
CCP1/
P1A
P1B
P1C
P1D
—
—
—
—
—
—
—
—
—
—
—
SS
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
OSC2/
CLKOUT
—
—
OSC1/CLKIN
INT0
Yes
INT1
Yes
INT2
Yes
—
Yes
KBI0
Yes
—
—
—
—
—
KBI1
Yes
PGM
KBI2
Yes
PGC
KBI3
Yes
PGD
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
SDI/
SDA
—
—
—
—
—
—
SDO
TX/CK
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
RX/DT
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
T1OSO/
T13CKI
PSP0
PSP1
PSP2
PSP3
PSP4
PSP5
PSP6
PSP7
RD
WR
CS
—
—
—
—
—
—
—
—
MCLR/VPP
VDD
VDD
VSS
VSS
VDD
VDD
VSS
CCP2 multiplexed with RB3 when CONFIG3H<0> = 0
CCP2 multiplexed with RC1 when CONFIG3H<0> = 1
Input-only.
 2010 Microchip Technology Inc.
DS41303G-page 7
PIC18F2XK20/4XK20
AN2
C2IN+
VREF-/
CVREF
AN3
C1IN+
VREF+
Basic
RA2
Pull-up
1
Interrupts
C12IN1-
4
Slave
C12IN0-
AN1
Timers
AN0
RA1
MSSP
Comparator
RA0
28
EUSART
Analog
27
3
ECCP
I/O
2
Reference
Pin QUAD
PIC18F2XK20 PIN SUMMARY
Pin DIL
TABLE 2:
5
2
RA3
6
3
RA4
7
4
RA5
10
7
RA6
OSC2/
CLKOUT
9
6
RA7
OSC1/
CLKIN
C1OUT
AN4
21
18
RB0
AN12
22
19
RB1
AN10
23
20
RB2
AN8
24
21
RB3
AN9
25
22
RB4
AN11
C2OUT
C12IN3C12IN2-
T0CKI
HLVDIN
SS
FLT0
INT0
P1C
INT1
Yes
P1B
INT2
Yes
KBI0
Yes
CCP2(1)
Yes
Yes
P1D
26
23
RB5
KBI1
Yes
PGM
27
24
RB6
KBI2
Yes
PGC
28
25
RB7
KBI3
Yes
PGD
11
8
RC0
T1OSO/
T13CKI
12
9
RC1
CCP2(2)
13
10
RC2
CCP1/
P1A
14
11
RC3
SCK/
SCL
15
12
RC4
SDI/
SDA
T1OSI
16
13
RC5
17
14
RC6
TX/CK
RX/DT
18
15
RC7
1
26
RE3(3)
SDO
MCLR/
VPP
8
5
VSS
19
16
VSS
20
17
VDD
Note 1:
2:
3:
CCP2 multiplexed with RB3 when CONFIG3H<0> = 0
CCP2 multiplexed with RC1 when CONFIG3H<0> = 1
Input-only
DS41303G-page 8
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
Table of Contents
1.0 Device Overview ....................................................................................................................................................................... 11
2.0 Oscillator Module (With Fail-Safe Clock Monitor)...................................................................................................................... 27
3.0 Power-Managed Modes ............................................................................................................................................................ 43
4.0 Reset ......................................................................................................................................................................................... 51
5.0 Memory Organization ................................................................................................................................................................ 65
6.0 Flash Program Memory............................................................................................................................................................. 89
7.0 Data EEPROM Memory ............................................................................................................................................................ 99
8.0 8 x 8 Hardware Multiplier......................................................................................................................................................... 105
9.0 Interrupts ................................................................................................................................................................................. 107
10.0 I/O Ports .................................................................................................................................................................................. 121
11.0 Capture/Compare/PWM (CCP) Modules ................................................................................................................................ 143
12.0 Timer0 Module ........................................................................................................................................................................ 155
13.0 Timer1 Module ........................................................................................................................................................................ 159
14.0 Timer2 Module ........................................................................................................................................................................ 167
15.0 Timer3 Module ........................................................................................................................................................................ 169
16.0 Enhanced Capture/Compare/PWM (ECCP) Module............................................................................................................... 173
17.0 Master Synchronous Serial Port (MSSP) Module ................................................................................................................... 193
18.0 Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) .............................................................. 237
19.0 Analog-to-Digital Converter (ADC) Module ............................................................................................................................. 265
20.0 Comparator Module................................................................................................................................................................. 279
21.0 Voltage References................................................................................................................................................................. 289
22.0 High/Low-Voltage Detect (HLVD)............................................................................................................................................ 293
23.0 Special Features of the CPU................................................................................................................................................... 299
24.0 Instruction Set Summary ......................................................................................................................................................... 315
25.0 Development Support.............................................................................................................................................................. 365
26.0 Electrical Characteristics ......................................................................................................................................................... 369
27.0 DC and AC Characteristics Graphs and Tables...................................................................................................................... 403
28.0 Packaging Information............................................................................................................................................................. 427
Appendix A: Revision History............................................................................................................................................................ 441
Appendix B: Device Differences ....................................................................................................................................................... 442
Index ................................................................................................................................................................................................. 443
The Microchip Web Site .................................................................................................................................................................... 453
Customer Change Notification Service ............................................................................................................................................. 453
Customer Support ............................................................................................................................................................................. 453
Reader Response ............................................................................................................................................................................. 454
Product Identification System ........................................................................................................................................................... 455
 2010 Microchip Technology Inc.
DS41303G-page 9
PIC18F2XK20/4XK20
TO OUR VALUED CUSTOMERS
It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip
products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and
enhanced as new volumes and updates are introduced.
If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via
E-mail at [email protected] or fax the Reader Response Form in the back of this data sheet to (480) 792-4150.
We welcome your feedback.
Most Current Data Sheet
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http://www.microchip.com
You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page.
The last character of the literature number is the version number, (e.g., DS30000A is version A of document DS30000).
Errata
An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current
devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the revision
of silicon and revision of document to which it applies.
To determine if an errata sheet exists for a particular device, please check with one of the following:
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When contacting a sales office or the literature center, please specify which device, revision of silicon and data sheet (include
literature number) you are using.
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DS41303G-page 10
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
1.0
DEVICE OVERVIEW
This document contains device specific information for
the following devices:
• PIC18F23K20
• PIC18F43K20
• PIC18F24K20
• PIC18F44K20
• PIC18F25K20
• PIC18F45K20
• PIC18F26K20
• PIC18F46K20
This family offers the advantages of all PIC18
microcontrollers – namely, high computational
performance at an economical price – with the addition
of high-endurance, Flash program memory. On top of
these features, the PIC18F2XK20/4XK20 family
introduces design enhancements that make these
microcontrollers a logical choice for many highperformance, power sensitive applications.
1.1
1.1.1
New Core Features
nanoWatt TECHNOLOGY
All of the devices in the PIC18F2XK20/4XK20 family
incorporate a range of features that can significantly
reduce power consumption during operation. Key
items include:
• Alternate Run Modes: By clocking the controller
from the Timer1 source or the internal oscillator
block, power consumption during code execution
can be reduced by as much as 90%.
• Multiple Idle Modes: The controller can also run
with its CPU core disabled but the peripherals still
active. In these states, power consumption can be
reduced even further, to as little as 4% of normal
operation requirements.
• On-the-fly Mode Switching: The powermanaged modes are invoked by user code during
operation, allowing the user to incorporate powersaving ideas into their application’s software
design.
• Low Consumption in Key Modules: The
power requirements for both Timer1 and the
Watchdog Timer are minimized. See
Section 26.0 “Electrical Characteristics”
for values.
 2010 Microchip Technology Inc.
1.1.2
MULTIPLE OSCILLATOR OPTIONS
AND FEATURES
All of the devices in the PIC18F2XK20/4XK20 family
offer ten different oscillator options, allowing users a
wide range of choices in developing application
hardware. These include:
• Four Crystal modes, using crystals or ceramic
resonators
• Two External Clock modes, offering the option of
using two pins (oscillator input and a divide-by-4
clock output) or one pin (oscillator input, with the
second pin reassigned as general I/O)
• Two External RC Oscillator modes with the same
pin options as the External Clock modes
• An internal oscillator block which contains a
16 MHz HFINTOSC oscillator and a 31 kHz
LFINTOSC oscillator which together provide 8
user selectable clock frequencies, from 31 kHz to
16 MHz. This option frees the two oscillator pins
for use as additional general purpose I/O.
• A Phase Lock Loop (PLL) frequency multiplier,
available to both the high-speed crystal and internal oscillator modes, which allows clock speeds of
up to 64 MHz. Used with the internal oscillator, the
PLL gives users a complete selection of clock
speeds, from 31 kHz to 64 MHz – all without using
an external crystal or clock circuit.
Besides its availability as a clock source, the internal
oscillator block provides a stable reference source that
gives the family additional features for robust
operation:
• Fail-Safe Clock Monitor: This option constantly
monitors the main clock source against a reference signal provided by the LFINTOSC. If a clock
failure occurs, the controller is switched to the
internal oscillator block, allowing for continued
operation or a safe application shutdown.
• Two-Speed Start-up: This option allows the
internal oscillator to serve as the clock source
from Power-on Reset, or wake-up from Sleep
mode, until the primary clock source is available.
DS41303G-page 11
PIC18F2XK20/4XK20
1.2
Other Special Features
• Memory Endurance: The Flash cells for both
program memory and data EEPROM are rated to
last for many thousands of erase/write cycles – up to
10K for program memory and 100K for EEPROM.
Data retention without refresh is conservatively
estimated to be greater than 40 years.
• Self-programmability: These devices can write
to their own program memory spaces under internal software control. By using a bootloader routine located in the protected Boot Block at the top
of program memory, it becomes possible to create
an application that can update itself in the field.
• Extended Instruction Set: The PIC18F2XK20/
4XK20 family introduces an optional extension to
the PIC18 instruction set, which adds 8 new
instructions and an Indexed Addressing mode.
This extension, enabled as a device configuration
option, has been specifically designed to optimize
re-entrant application code originally developed in
high-level languages, such as C.
• Enhanced CCP module: In PWM mode, this
module provides 1, 2 or 4 modulated outputs for
controlling half-bridge and full-bridge drivers.
Other features include:
- Auto-Shutdown, for disabling PWM outputs
on interrupt or other select conditions
- Auto-Restart, to reactivate outputs once the
condition has cleared
- Output steering to selectively enable one or
more of 4 outputs to provide the PWM signal.
• Enhanced Addressable USART: This serial
communication module is capable of standard
RS-232 operation and provides support for the LIN
bus protocol. Other enhancements include
automatic baud rate detection and a 16-bit Baud
Rate Generator for improved resolution. When the
microcontroller is using the internal oscillator
block, the USART provides stable operation for
applications that talk to the outside world without
using an external crystal (or its accompanying
power requirement).
• 10-bit A/D Converter: This module incorporates
programmable acquisition time, allowing for a
channel to be selected and a conversion to be
initiated without waiting for a sampling period and
thus, reduce code overhead.
• Extended Watchdog Timer (WDT): This
enhanced version incorporates a 16-bit
postscaler, allowing an extended time-out range
that is stable across operating voltage and
temperature. See Section 26.0 “Electrical
Characteristics” for time-out periods.
DS41303G-page 12
1.3
Details on Individual Family
Members
Devices in the PIC18F2XK20/4XK20 family are available in 28-pin and 40/44-pin packages. Block diagrams
for the two groups are shown in Figure 1-1 and
Figure 1-2.
The devices are differentiated from each other in five
ways:
1.
2.
3.
4.
Flash program memory (8 Kbytes for
PIC18F23K20/43K20 devices, 16 Kbytes for
PIC18F24K20/44K20 devices, 32 Kbytes for
PIC18F25K20/45K20 AND 64 Kbytes for
PIC18F26K20/46K20).
A/D channels (11 for 28-pin devices, 14 for
40/44-pin devices).
I/O ports (3 bidirectional ports on 28-pin devices,
5 bidirectional ports on 40/44-pin devices).
Parallel Slave Port (present only on 40/44-pin
devices).
All other features for devices in this family are identical.
These are summarized in Table 1-1.
The pinouts for all devices are listed in the pin summary
tables: Table 1 and Table 2, and I/O description tables:
Table 1-2 and Table 1-3.
 2010 Microchip Technology Inc.
 2010 Microchip Technology Inc.
TABLE 1-1:
DEVICE FEATURES
Features
Operating
Frequency(2)
PIC18F23K20
PIC18F24K20
PIC18F25K20
PIC18F26K20
PIC18F43K20
PIC18F44K20
PIC18F45K20
PIC18F46K20
DC – 64 MHz
DC – 64 MHz
DC – 64 MHz
DC – 64 MHz
DC – 64 MHz
DC – 64 MHz
DC – 64 MHz
DC – 64 MHz
Program Memory (Bytes)
8192
16384
32768
65536
8192
16384
32768
65536
Program Memory
(Instructions)
4096
8192
16384
32768
4096
8192
16384
32768
Data Memory (Bytes)
512
768
1536
3936
512
768
1536
3936
Data EEPROM Memory
(Bytes)
256
256
256
1024
256
256
256
1024
Interrupt Sources
I/O Ports
19
19
19
19
20
20
20
20
A, B, C, (E)(1)
A, B, C, (E)(1)
A, B, C, (E)(1)
A, B, C, (E)(1)
A, B, C, D, E
A, B, C, D, E
A, B, C, D, E
A, B, C, D, E
Timers
4
4
44
Capture/Compare/PWM
Modules
1
1
1
Enhanced Capture/
Compare/PWM Modules
1
1
11
MSSP, Enhanced
USART
MSSP, Enhanced
USART
MSSP, Enhanced
USART
MSSP, Enhanced
USART
MSSP, Enhanced
USART
MSSP, Enhanced
USART
MSSP, Enhanced
USART
MSSP, Enhanced
USART
No
No
No
No
Yes
Yes
Yes
Yes
1 internal plus 10
Input Channels
1 internal plus 10
Input Channels
1 internal plus 10
Input Channels
1 internal plus 10
Input Channels
1 internal plus 13
Input Channels
1 internal plus 13
Input Channels
1 internal plus 13
Input Channels
1 internal plus 13
Input Channels
Resets (and Delays)
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST),
MCLR (optional),
WDT
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST), MCLR
(optional), WDT
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST),
MCLR (optional),
WDT
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST), MCLR
(optional), WDT
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST),
MCLR (optional),
WDT
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST),
MCLR (optional),
WDT
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST),
MCLR (optional),
WDT
POR, BOR, RESET
Instruction, Stack
Full, Stack Underflow
(PWRT, OST), MCLR
(optional), WDT
Programmable High/
Low-Voltage Detect
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Programmable Brownout Reset
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
75 Instructions; 83
with Extended
Instruction Set
enabled
75 Instructions; 83
with Extended
Instruction Set
enabled
75 Instructions; 83
with Extended
Instruction Set
enabled
75 Instructions; 83
with Extended
Instruction Set
enabled
75 Instructions; 83
with Extended
Instruction Set
enabled
75 Instructions; 83
with Extended
Instruction Set
enabled
75 Instructions; 83
with Extended
Instruction Set
enabled
75 Instructions; 83
with Extended
Instruction Set
enabled
28-pin PDIP
28-pin SOIC
28-pin QFN
28-pin SSOP
28-pin UQFN
28-pin PDIP
28-pin SOIC
28-pin QFN
28-pin SSOP
28-pin PDIP
28-pin SOIC
28-pin QFN
28-pin SSOP
28-pin PDIP
28-pin SOIC
28-pin QFN
28-pin SSOP
40-pin PDIP
44-pin QFN
44-pin TQFP
40-pin PDIP
44-pin QFN
44-pin TQFP
40-pin PDIP
44-pin QFN
44-pin TQFP
40-pin PDIP
44-pin QFN
44-pin TQFP
Serial Communications
Parallel Communications (PSP)
10-bit Analog-to-Digital
Module
Packages
DS41303G-page 13
Note
1
44
1
11
1:
PORTE contains the single RE3 read-only bit. The LATE and TRISE registers are not implemented.
2:
Frequency range shown applies to industrial range devices only. Maximum frequency for extended range devices is 48 MHz.
1
1
11
PIC18F2XK20/4XK20
Instruction Set
44
1
PIC18F2XK20/4XK20
FIGURE 1-1:
PIC18F2XK20 (28-PIN) BLOCK DIAGRAM
Data Bus<8>
Table Pointer<21>
Data Latch
8
8
inc/dec logic
PORTA
Data Memory
PCLATU PCLATH
21
Address Latch
20
PCU PCH PCL
Program Counter
12
Data Address<12>
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
OSC2/CLKOUT(3)/RA6
OSC1/CLKIN(3)/RA7
31-Level Stack
4
BSR
Address Latch
Program Memory
(8/16/32/64 Kbytes)
STKPTR
12
FSR0
FSR1
FSR2
Data Latch
4
Access
Bank
12
PORTB
8
inc/dec
logic
Table Latch
Address
Decode
ROM Latch
Instruction Bus <16>
RB0/INT0/FLT0/AN12
RB1/INT1/AN10/C12IN3RB2/INT2/AN8
RB3/AN9/CCP2(1)/C12IN2RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
IR
8
Instruction
Decode and
Control
State machine
control signals
PRODH PRODL
PORTC
8
W
BITOP
8
Internal
Oscillator
Block
OSC1(3)
OSC2
(3)
T1OSI
LFINTOSC
Oscillator
T1OSO
16 MHz
Oscillator
Single-Supply
Programming
In-Circuit
Debugger
MCLR(2)
VDD, VSS
BOR
HLVD
FVR
CVREF Comparator
Note
Power-up
Timer
8
8
8
8
Oscillator
Start-up Timer
Power-on
Reset
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1
RC3/SCK/SCL
RC4/SDI/SDA
RC5/SDO
RC6/TX/CK
RC7/RX/DT
8 x 8 Multiply
3
ALU<8>
8
Watchdog
Timer
Brown-out
Reset
Fail-Safe
Clock Monitor
Precision
Band Gap
Reference
FVR
PORTE
MCLR/VPP/RE3(2)
Data
EEPROM
Timer0
Timer1
Timer2
Timer3
ECCP1
CCP2
MSSP
EUSART
ADC
10-bit
FVR
1:
CCP2 is multiplexed with RC1 when Configuration bit CCP2MX is set, or RB3 when CCP2MX is not set.
2:
RE3 is only available when MCLR functionality is disabled.
3:
OSC1/CLKIN and OSC2/CLKOUT are only available in select oscillator modes and when these pins are not being used as digital I/O.
Refer to Section 2.0 “Oscillator Module (With Fail-Safe Clock Monitor)” for additional information.
DS41303G-page 14
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 1-2:
PIC18F4XK20 (40/44-PIN) BLOCK DIAGRAM
Data Bus<8>
PORTA
Table Pointer<21>
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
OSC2/CLKOUT(3)/RA6
OSC1/CLKIN(3)/RA7
Data Latch
8
8
inc/dec logic
Data Memory
PCLATU PCLATH
21
Address Latch
20
PCU PCH PCL
Program Counter
12
Data Address<12>
PORTB
31-Level Stack
4
BSR
Address Latch
Program Memory
(8/16/32/64 Kbytes)
STKPTR
FSR0
FSR1
FSR2
Data Latch
8
RB0/INT0/FLT0/AN12
RB1/INT1/AN10/C12IN3RB2/INT2/AN8
RB3/AN9/CCP2(1)/C12IN2RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
4
Access
Bank
12
12
inc/dec
logic
Table Latch
PORTC
Address
Decode
ROM Latch
Instruction Bus <16>
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1/P1A
RC3/SCK/SCL
RC4/SDI/SDA
RC5/SDO
RC6/TX/CK
RC7/RX/DT
IR
8
Instruction
Decode and
Control
State machine
control signals
PRODH PRODL
PORTD
8 x 8 Multiply
3
W
BITOP
8
Internal
Oscillator
Block
OSC1(3)
OSC2
(3)
T1OSI
LFINTOSC
Oscillator
T1OSO
16 MHz
Oscillator
Single-Supply
Programming
In-Circuit
Debugger
MCLR(2)
VDD, VSS
BOR
HLVD
Power-up
Timer
8
Note
8
8
8
Oscillator
Start-up Timer
Power-on
Reset
ALU<8>
8
Watchdog
Timer
PORTE
Brown-out
Reset
Fail-Safe
Clock Monitor
Precision
Band Gap
Reference
RE0/RD/AN5
RE1/WR/AN6
RE2/CS/AN7
MCLR/VPP/RE3(2)
FVR
Data
EEPROM
Timer0
Timer1
Timer2
Timer3
ECCP1
CCP2
MSSP
EUSART
ADC
10-bit
FVR
CVREF Comparator
RD0/PSP0
RD1/PSP1
RD2/PSP2
RD3/PSP3
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
8
FVR
PSP
1:
CCP2 is multiplexed with RC1 when Configuration bit CCP2MX is set, or RB3 when CCP2MX is not set.
2:
RE3 is only available when MCLR functionality is disabled.
3:
OSC1/CLKIN and OSC2/CLKOUT are only available in select oscillator modes and when these pins are not being used as digital I/O.
Refer to Section 2.0 “Oscillator Module (With Fail-Safe Clock Monitor)” for additional information.
 2010 Microchip Technology Inc.
DS41303G-page 15
PIC18F2XK20/4XK20
TABLE 1-2:
PIC18F2XK20 PINOUT I/O DESCRIPTIONS
Pin Number
Pin Name
Pin Buffer
PDIP,
QFN Type Type
SOIC
MCLR/VPP/RE3
MCLR
VPP
RE3
1
OSC1/CLKIN/RA7
OSC1
9
26
I
P
I
6
ST
ST
ST
O
—
CLKOUT
O
—
RA6
I/O
TTL
RA7
OSC2/CLKOUT/RA6
OSC2
10
Master Clear (input) or programming voltage (input)
Active-low Master Clear (device Reset) input
Programming voltage input
Digital input
Oscillator crystal or external clock input
Oscillator crystal input or external clock source input
ST buffer when configured in RC mode; CMOS otherwise
I CMOS
External clock source input. Always associated with pin
function OSC1. (See related OSC1/CLKIN, OSC2/CLKOUT
pins)
I/O
TTL
General purpose I/O pin
I
CLKIN
Description
7
Oscillator crystal or clock output
Oscillator crystal output. Connects to crystal or
resonator in Crystal Oscillator mode
In RC mode, OSC2 pin outputs CLKOUT which has 1/4 the
frequency of OSC1 and denotes the instruction cycle rate
General purpose I/O pin
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
DS41303G-page 16
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 1-2:
PIC18F2XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
Pin Buffer
PDIP,
QFN Type Type
SOIC
Description
PORTA is a bidirectional I/O port.
RA0/AN0/C12IN0RA0
AN0
C12IN0-
2
RA1/AN1/C12IN1RA1
AN1
C12IN1-
3
RA2/AN2/VREF-/CVREF/
C2IN+
RA2
AN2
VREFCVREF
C2IN+
4
RA3/AN3/VREF+/C1IN+
RA3
AN3
VREF+
C1IN+
5
RA4/T0CKI/C1OUT
RA4
T0CKI
C1OUT
6
RA5/AN4/SS/HLVDIN/
C2OUT
RA5
AN4
SS
HLVDIN
C2OUT
7
27
I/O
TTL
I Analog
I Analog
Digital I/O
Analog input 0, ADC channel 0
Comparators C1 and C2 inverting input
I/O
TTL
I Analog
I Analog
Digital I/O
ADC input 1, ADC channel 1
Comparators C1 and C2 inverting input
I/O
I
I
O
I
Digital I/O
Analog input 2, ADC channel 2
A/D reference voltage (low) input
Comparator reference voltage output
Comparator C2 non-inverting input
28
1
TTL
Analog
Analog
Analog
Analog
2
I/O
TTL
I Analog
I Analog
I Analog
Digital I/O
Analog input 3, ADC channel 3
A/D reference voltage (high) input
Comparator C1 non-inverting input
I/O
ST
I
ST
O CMOS
Digital I/O
Timer0 external clock input
Comparator C1 output
I/O
TTL
I Analog
I
TTL
I Analog
O CMOS
Digital I/O
Analog input 4, ADC channel 4
SPI slave select input
High/Low-Voltage Detect input
Comparator C2 output
3
4
RA6
See the OSC2/CLKOUT/RA6 pin
RA7
See the OSC1/CLKIN/RA7 pin
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
 2010 Microchip Technology Inc.
DS41303G-page 17
PIC18F2XK20/4XK20
TABLE 1-2:
PIC18F2XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
Pin Buffer
PDIP,
QFN Type Type
SOIC
Description
PORTB is a bidirectional I/O port. PORTB can be software
programmed for internal weak pull-up on each input.
RB0/INT0/FLT0/AN12
RB0
INT0
FLT0
AN12
21
RB1/INT1/AN10/C12IN3/P1C
RB1
INT1
AN10
C12IN3P1C
22
RB2/INT2/AN8/P1B
RB2
INT2
AN8
P1B
23
RB3/AN9/C12IN2-/CCP2
RB3
AN9
C12IN2CCP2(2)
24
RB4/KBI0/AN11/P1D
RB4
KBI0
AN11
P1D
25
RB5/KBI1/PGM
RB5
KBI1
PGM
26
RB6/KBI2/PGC
RB6
KBI2
PGC
27
RB7/KBI3/PGD
RB7
KBI3
PGD
28
18
I/O
TTL
I
ST
I
ST
I Analog
Digital I/O
External interrupt 0
PWM Fault input for CCP1
Analog input 12, ADC channel 12
I/O
TTL
I
ST
I Analog
I Analog
O CMOS
Digital I/O
External interrupt 1
Analog input 10, ADC channel 10
Comparators C1 and C2 inverting input
Enhanced CCP1 PWM output
I/O
TTL
I
ST
I Analog
O CMOS
Digital I/O
External interrupt 2
Analog input 8, ADC channel 8
Enhanced CCP1 PWM output
I/O
TTL
I Analog
I Analog
I/O
ST
Digital I/O
Analog input 9, ADC channel 9
Comparators C1 and C2 inverting input
Capture 2 input/Compare 2 output/PWM 2 output
I/O
TTL
I
TTL
I Analog
O CMOS
Digital I/O
Interrupt-on-change pin
Analog input 11, ADC channel 11
Enhanced CCP1 PWM output
I/O
I
I/O
TTL
TTL
ST
Digital I/O
Interrupt-on-change pin
Low-Voltage ICSP™ Programming enable pin
I/O
I
I/O
TTL
TTL
ST
Digital I/O
Interrupt-on-change pin
In-Circuit Debugger and ICSP™ programming clock pin
I/O
I
I/O
TTL
TTL
ST
Digital I/O
Interrupt-on-change pin
In-Circuit Debugger and ICSP™ programming data pin
19
20
21
22
23
24
25
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
DS41303G-page 18
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 1-2:
PIC18F2XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
Pin Buffer
PDIP,
QFN Type Type
SOIC
Description
PORTC is a bidirectional I/O port.
RC0/T1OSO/T13CKI
RC0
T1OSO
T13CKI
11
RC1/T1OSI/CCP2
RC1
T1OSI
CCP2(1)
12
RC2/CCP1/P1A
RC2
CCP1
P1A
13
RC3/SCK/SCL
RC3
SCK
SCL
14
RC4/SDI/SDA
RC4
SDI
SDA
15
RC5/SDO
RC5
SDO
16
RC6/TX/CK
RC6
TX
CK
17
RC7/RX/DT
RC7
RX
DT
18
RE3
VSS
VDD
8
I/O
O
I
—
Digital I/O
Timer1 oscillator output
Timer1/Timer3 external clock input
9
I/O
ST
I Analog
I/O
ST
Digital I/O
Timer1 oscillator input
Capture 2 input/Compare 2 output/PWM 2 output
I/O
ST
I/O
ST
O CMOS
Digital I/O
Capture 1 input/Compare 1 output
Enhanced CCP1 PWM output
10
11
I/O
I/O
I/O
ST
ST
ST
Digital I/O
Synchronous serial clock input/output for SPI mode
Synchronous serial clock input/output for I2C™ mode
I/O
I
I/O
ST
ST
ST
Digital I/O
SPI data in
I2C™ data I/O
I/O
O
ST
—
Digital I/O
SPI data out
I/O
O
I/O
ST
—
ST
Digital I/O
EUSART asynchronous transmit
EUSART synchronous clock (see related RX/DT)
I/O
I
I/O
ST
ST
ST
Digital I/O
EUSART asynchronous receive
EUSART synchronous data (see related TX/CK)
—
—
See MCLR/VPP/RE3 pin
P
—
Ground reference for logic and I/O pins
P
—
Positive supply for logic and I/O pins
12
13
14
15
—
8, 19 5, 16
20
ST
—
ST
17
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
 2010 Microchip Technology Inc.
DS41303G-page 19
PIC18F2XK20/4XK20
TABLE 1-3:
PIC18F4XK20 PINOUT I/O DESCRIPTIONS
Pin Name
Pin Number
PDIP
MCLR/VPP/RE3
MCLR
VPP
RE3
1
OSC1/CLKIN/RA7
OSC1
13
Pin Buffer
QFN TQFP Type Type
18
18
I
P
I
32
30
I
CLKIN
I
RA7
OSC2/CLKOUT/RA6
OSC2
I/O
14
33
ST
ST
Description
Master Clear (input) or programming voltage (input)
Active-low Master Clear (device Reset) input
Programming voltage input
Digital input
Oscillator crystal or external clock input
Oscillator crystal input or external clock source input
ST buffer when configured in RC mode;
analog otherwise
CMOS
External clock source input. Always associated with
pin function OSC1 (See related OSC1/CLKIN,
OSC2/CLKOUT pins)
TTL
General purpose I/O pin
ST
31
O
—
CLKOUT
O
—
RA6
I/O
TTL
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
Oscillator crystal or clock output
Oscillator crystal output. Connects to crystal
or resonator in Crystal Oscillator mode
In RC mode, OSC2 pin outputs CLKOUT which
has 1/4 the frequency of OSC1 and denotes
the instruction cycle rate
General purpose I/O pin
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
DS41303G-page 20
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 1-3:
PIC18F4XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
PDIP
Pin Buffer
QFN TQFP Type Type
Description
PORTA is a bidirectional I/O port.
RA0/AN0/C12IN0RA0
AN0
C12IN0-
2
RA1/AN1/C12IN0RA1
AN1
C12IN0-
3
RA2/AN2/VREF-/CVREF/
C2IN+
RA2
AN2
VREFCVREF
C2IN+
4
RA3/AN3/VREF+/
C1IN+
RA3
AN3
VREF+
C1IN+
5
RA4/T0CKI/C1OUT
RA4
T0CKI
C1OUT
6
RA5/AN4/SS/HLVDIN/
C2OUT
RA5
AN4
SS
HLVDIN
C2OUT
7
19
20
21
22
23
24
19
I/O
I
I
TTL
Analog
Analog
Digital I/O
Analog input 0, ADC channel 0
Comparator C1 and C2 inverting input
I/O
I
I
TTL
Analog
Analog
Digital I/O
Analog input 1, ADC channel 1
Comparator C1 and C2 inverting input
I/O
I
I
O
I
TTL
Analog
Analog
Analog
Analog
Digital I/O
Analog input 2, ADC channel 2
A/D reference voltage (low) input
Comparator reference voltage output
Comparator C2 non-inverting input
I/O
I
I
I
TTL
Analog
Analog
Analog
Digital I/O
Analog input 3, ADC channel 3
A/D reference voltage (high) input
Comparator C1 non-inverting input
I/O
I
O
ST
ST
CMOS
Digital I/O
Timer0 external clock input
Comparator C1 output
I/O
I
I
I
O
TTL
Analog
TTL
Analog
CMOS
Digital I/O
Analog input 4, ADC channel 4
SPI slave select input
High/Low-Voltage Detect input
Comparator C2 output
20
21
22
23
24
RA6
RA7
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
See the OSC2/CLKOUT/RA6 pin
See the OSC1/CLKIN/RA7 pin
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
 2010 Microchip Technology Inc.
DS41303G-page 21
PIC18F2XK20/4XK20
TABLE 1-3:
PIC18F4XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
PDIP
Pin Buffer
QFN TQFP Type Type
Description
PORTB is a bidirectional I/O port. PORTB can be
software programmed for internal weak pull-up on
each input.
RB0/INT0/FLT0/AN12
RB0
INT0
FLT0
AN12
33
RB1/INT1/AN10/
C12IN3RB1
INT1
AN10
C12IN3-
34
RB2/INT2/AN8
RB2
INT2
AN8
35
RB3/AN9/C12IN2-/
CCP2
RB3
AN9
C12IN23CCP2(2)
36
RB4/KBI0/AN11
RB4
KBI0
AN11
37
RB5/KBI1/PGM
RB5
KBI1
PGM
38
RB6/KBI2/PGC
RB6
KBI2
PGC
39
RB7/KBI3/PGD
RB7
KBI3
PGD
40
9
10
11
12
14
15
16
17
8
I/O
I
I
I
TTL
ST
ST
Analog
Digital I/O
External interrupt 0
PWM Fault input for Enhanced CCP1
Analog input 12, ADC channel 12
I/O
I
I
I
TTL
ST
Analog
Analog
Digital I/O
External interrupt 1
Analog input 10, ADC channel 10
Comparator C1 and C2 inverting input
I/O
I
I
TTL
ST
Analog
Digital I/O
External interrupt 2
Analog input 8, ADC channel 8
I/O
I
I
I/O
TTL
Analog
Analog
ST
Digital I/O
Analog input 9, ADC channel 9
Comparator C1 and C2 inverting input
Capture 2 input/Compare 2 output/PWM 2 output
I/O
I
I
TTL
TTL
Analog
Digital I/O
Interrupt-on-change pin
Analog input 11, ADC channel 11
I/O
I
I/O
TTL
TTL
ST
Digital I/O
Interrupt-on-change pin
Low-Voltage ICSP™ Programming enable pin
I/O
I
I/O
TTL
TTL
ST
Digital I/O
Interrupt-on-change pin
In-Circuit Debugger and ICSP™ programming
clock pin
I/O
I
I/O
TTL
TTL
ST
Digital I/O
Interrupt-on-change pin
In-Circuit Debugger and ICSP™ programming
data pin
9
10
11
14
15
16
17
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
DS41303G-page 22
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 1-3:
PIC18F4XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
PDIP
Pin Buffer
QFN TQFP Type Type
Description
PORTC is a bidirectional I/O port.
RC0/T1OSO/T13CKI
RC0
T1OSO
T13CKI
15
RC1/T1OSI/CCP2
RC1
T1OSI
CCP2(1)
16
RC2/CCP1/P1A
RC2
CCP1
P1A
17
RC3/SCK/SCL
RC3
SCK
18
34
35
36
37
32
23
RC5/SDO
RC5
SDO
24
RC6/TX/CK
RC6
TX
CK
25
RC7/RX/DT
RC7
RX
DT
26
42
43
44
1
ST
—
ST
I/O
I
I/O
ST
CMOS
ST
Digital I/O
Timer1 oscillator input
Capture 2 input/Compare 2 output/PWM 2 output
I/O
I/O
O
ST
ST
—
Digital I/O
Capture 1 input/Compare 1 output/PWM 1 output
Enhanced CCP1 output
I/O
I/O
ST
ST
I/O
ST
Digital I/O
Synchronous serial clock input/output for
SPI mode
Synchronous serial clock input/output for I2C™ mode
I/O
I
I/O
ST
ST
ST
Digital I/O
SPI data in
I2C™ data I/O
I/O
O
ST
—
Digital I/O
SPI data out
I/O
O
I/O
ST
—
ST
Digital I/O
EUSART asynchronous transmit
EUSART synchronous clock (see related RX/DT)
I/O
I
I/O
ST
ST
ST
Digital I/O
EUSART asynchronous receive
EUSART synchronous data (see related TX/CK)
Digital I/O
Timer1 oscillator output
Timer1/Timer3 external clock input
35
36
37
SCL
RC4/SDI/SDA
RC4
SDI
SDA
I/O
O
I
42
43
44
1
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
 2010 Microchip Technology Inc.
DS41303G-page 23
PIC18F2XK20/4XK20
TABLE 1-3:
Pin Name
PIC18F4XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
PDIP
Pin Buffer
QFN TQFP Type Type
Description
PORTD is a bidirectional I/O port or a Parallel Slave
Port (PSP) for interfacing to a microprocessor port.
These pins have TTL input buffers when PSP module
is enabled.
RD0/PSP0
RD0
PSP0
19
RD1/PSP1
RD1
PSP1
20
RD2/PSP2
RD2
PSP2
21
RD3/PSP3
RD3
PSP3
22
RD4/PSP4
RD4
PSP4
27
RD5/PSP5/P1B
RD5
PSP5
P1B
28
RD6/PSP6/P1C
RD6
PSP6
P1C
29
RD7/PSP7/P1D
RD7
PSP7
P1D
30
38
39
40
41
2
3
4
5
38
I/O
I/O
ST
TTL
Digital I/O
Parallel Slave Port data
I/O
I/O
ST
TTL
Digital I/O
Parallel Slave Port data
I/O
I/O
ST
TTL
Digital I/O
Parallel Slave Port data
I/O
I/O
ST
TTL
Digital I/O
Parallel Slave Port data
I/O
I/O
ST
TTL
Digital I/O
Parallel Slave Port data
I/O
I/O
O
ST
TTL
—
Digital I/O
Parallel Slave Port data
Enhanced CCP1 output
I/O
I/O
O
ST
TTL
—
Digital I/O
Parallel Slave Port data
Enhanced CCP1 output
I/O
I/O
O
ST
TTL
—
Digital I/O
Parallel Slave Port data
Enhanced CCP1 output
39
40
41
2
3
4
5
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
DS41303G-page 24
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 1-3:
Pin Name
PIC18F4XK20 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
PDIP
Pin Buffer
QFN TQFP Type Type
Description
PORTE is a bidirectional I/O port
RE0/RD/AN5
RE0
RD
8
25
25
AN5
RE1/WR/AN6
RE1
WR
9
26
10
27
—
I
Analog
I/O
I
ST
TTL
I
Analog
I/O
I
ST
TTL
Digital I/O
Read control for Parallel Slave Port
(see related WR and CS pins)
Analog input 5, ADC channel 5
Digital I/O
Write control for Parallel Slave Port
(see related CS and RD pins)
Analog input 6, ADC channel 6
27
AN7
RE3
ST
TTL
26
AN6
RE2/CS/AN7
RE2
CS
I/O
I
Digital I/O
Chip Select control for Parallel Slave Port
(see related RD and WR)
Analog input 7, ADC channel 7
I
Analog
—
—
—
See MCLR/VPP/RE3 pin
6, 29
P
—
Ground reference for logic and I/O pins
7, 8, 7, 28
28, 29
P
—
Positive supply for logic and I/O pins
—
—
No connect
—
VSS
12, 31 6, 30,
31
VDD
11, 32
NC
—
13
12, 13,
33, 34
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
CMOS = CMOS compatible input or output
I
= Input
P
= Power
Note 1: Default assignment for CCP2 when Configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when Configuration bit CCP2MX is cleared.
 2010 Microchip Technology Inc.
DS41303G-page 25
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 26
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
2.0
OSCILLATOR MODULE (WITH
FAIL-SAFE CLOCK MONITOR)
2.1
Overview
The Oscillator module can be configured in one of ten
primary clock modes.
1.
2.
3.
4.
Low-Power Crystal
Crystal/Resonator
High-Speed Crystal/Resonator
High-Speed Crystal/Resonator
with PLL enabled
5. RC
External Resistor/Capacitor with
FOSC/4 output on RA6
6. RCIO
External Resistor/Capacitor with I/O
on RA6
7. INTOSC Internal Oscillator with FOSC/4
output on RA6 and I/O on RA7
8. INTOSCIO Internal Oscillator with I/O on RA6
and RA7
9. EC
External Clock with FOSC/4 output
10. ECIO
External Clock with I/O on RA6
The Oscillator module has a wide variety of clock
sources and selection features that allow it to be used
in a wide range of applications while maximizing performance and minimizing power consumption. Figure 2-1
illustrates a block diagram of the Oscillator module.
Clock sources can be configured from external
oscillators, quartz crystal resonators, ceramic resonators
and Resistor-Capacitor (RC) circuits. In addition, the
system clock source can be configured from one of two
internal oscillators, with a choice of speeds selectable via
software. Additional clock features include:
• Selectable system clock source between external
or internal via software.
• Two-Speed Start-up mode, which minimizes
latency between external oscillator start-up and
code execution.
• Fail-Safe Clock Monitor (FSCM) designed to
detect a failure of the external clock source (LP,
XT, HS, EC or RC modes) and switch
automatically to the internal oscillator.
LP
XT
HS
HSPLL
Primary Clock modes are selected by the FOSC<3:0>
bits of the CONFIG1H Configuration Register. The
HFINTOSC and LFINTOSC are factory calibrated highfrequency and low-frequency oscillators, respectively,
which are used as the internal clock sources.
PIC® MCU CLOCK SOURCE BLOCK DIAGRAM
FIGURE 2-1:
PIC18F2XK20/4XK20
Primary Oscillator
LP, XT, HS, RC, EC
OSC2
IDLEN
Sleep
4 x PLL
OSC1
HSPLL, HFINTOSC/PLL
Sleep
Secondary Oscillator
T1OSC
T1OSO
T1OSCEN
Enable
Oscillator
OSCCON<6:4>
16 MHz
FOSC<3:0> OSCCON<1:0>
31 kHz
Source
Main
16 MHz
(HFINTOSC)
31 kHz (LFINTOSC)
2 MHz
1 MHz
500 kHz
250 kHz
Peripherals
Internal Oscillator
CPU
111
Sleep
110
4 MHz
Postscaler
Internal
Oscillator
Block
16 MHz
Source
8 MHz
101
100
011
MUX
T1OSI
MUX
OSCTUNE<6>(1)
010
001
1 31 kHz
000
0
Clock
Control
FOSC<3:0> OSCCON<1:0>
Clock Source Option
for other Modules
OSCTUNE<7>
WDT, PWRT, FSCM
and Two-Speed Start-up
Note
1:
Operates only when HFINTOSC is the primary oscillator.
 2010 Microchip Technology Inc.
DS41303G-page 27
PIC18F2XK20/4XK20
2.2
Oscillator Control
The OSCCON register (Register 2-1) controls several
aspects of the device clock’s operation, both in full
power operation and in power-managed modes.
•
•
•
•
Main System Clock Selection (SCS)
Internal Frequency selection bits (IRCF)
Clock Status bits (OSTS, IOFS)
Power management selection (IDLEN)
2.2.1
MAIN SYSTEM CLOCK SELECTION
The System Clock Select bits, SCS<1:0>, select the
main clock source. The available clock sources are
• Primary clock defined by the FOSC<3:0> bits of
CONFIG1H. The primary clock can be the primary
oscillator, an external clock, or the internal oscillator block.
• Secondary clock (Timer1 oscillator)
• Internal oscillator block (HFINTOSC and
LFINTOSC).
The clock source changes immediately after one or
more of the bits is written to, following a brief clock transition interval. The SCS bits are cleared to select the
primary clock on all forms of Reset.
2.2.2
INTERNAL FREQUENCY
SELECTION
The Internal Oscillator Frequency Select bits
(IRCF<2:0>) select the frequency output of the internal
oscillator block. The choices are the LFINTOSC source
(31 kHz), the HFINTOSC source (16 MHz) or one of
the frequencies derived from the HFINTOSC postscaler (31.25 kHz to 8 MHz). If the internal oscillator
block is supplying the main clock, changing the states
of these bits will have an immediate change on the
internal oscillator’s output. On device Resets, the output frequency of the internal oscillator is set to the
default frequency of 1 MHz.
2.2.3
2.2.4
CLOCK STATUS
The OSTS and IOFS bits of the OSCCON register, and
the T1RUN bit of the T1CON register, indicate which
clock source is currently providing the main clock. The
OSTS bit indicates that the Oscillator Start-up Timer
has timed out and the primary clock is providing the
device clock. The IOFS bit indicates when the internal
oscillator block has stabilized and is providing the
device clock in HFINTOSC Clock modes. The IOFS
and OSTS Status bits will both be set when
SCS<1:0> = 00 and HFINTOSC is the primary clock.
The T1RUN bit indicates when the Timer1 oscillator is
providing the device clock in secondary clock modes.
When SCS<1:0>  00, only one of these three bits will
be set at any time. If none of these bits are set, the
LFINTOSC is providing the clock or the HFINTOSC
has just started and is not yet stable.
2.2.5
POWER MANAGEMENT
The IDLEN bit of the OSCCON register determines if
the device goes into Sleep mode or one of the Idle
modes when the SLEEP instruction is executed.
The use of the flag and control bits in the OSCCON
register is discussed in more detail in Section 3.0
“Power-Managed Modes”.
Note 1: The Timer1 oscillator must be enabled to
select the secondary clock source. The
Timer1 oscillator is enabled by setting the
T1OSCEN bit of the T1CON register. If
the Timer1 oscillator is not enabled, then
the main oscillator will continue to run
from the previously selected source. The
source will then switch to the secondary
oscillator after the T1OSCEN bit is set.
2: It is recommended that the Timer1
oscillator be operating and stable before
selecting the secondary clock source or a
very long delay may occur while the
Timer1 oscillator starts.
LOW FREQUENCY SELECTION
When a nominal output frequency of 31 kHz is selected
(IRCF<2:0> = 000), users may choose which internal
oscillator acts as the source. This is done with the
INTSRC bit of the OSCTUNE register. Setting this bit
selects the HFINTOSC as a 31.25 kHz clock source by
enabling the divide-by-512 output of the HFINTOSC
postscaler. Clearing INTSRC selects LFINTOSC (nominally 31 kHz) as the clock source.
This option allows users to select the tunable and more
precise HFINTOSC as a clock source, while maintaining power savings with a very low clock speed. Regardless of the setting of INTSRC, LFINTOSC always
remains the clock source for features such as the
Watchdog Timer and the Fail-Safe Clock Monitor.
DS41303G-page 28
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 2-1:
OSCCON: OSCILLATOR CONTROL REGISTER
R/W-0
R/W-0
R/W-1
R/W-1
R-q
R-0
R/W-0
R/W-0
IDLEN
IRCF2
IRCF1
IRCF0
OSTS(1)
IOFS
SCS1
SCS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
q = depends on condition
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
IDLEN: Idle Enable bit
1 = Device enters Idle mode on SLEEP instruction
0 = Device enters Sleep mode on SLEEP instruction
bit 6-4
IRCF<2:0>: Internal Oscillator Frequency Select bits
111 = 16 MHz (HFINTOSC drives clock directly)
110 = 8 MHz
101 = 4 MHz
100 = 2 MHz
011 = 1 MHz(3)
010 = 500 kHz
001 = 250 kHz
000 = 31 kHz (from either HFINTOSC/512 or LFINTOSC directly)(2)
bit 3
OSTS: Oscillator Start-up Time-out Status bit(1)
1 = Device is running from the clock defined by FOSC<2:0> of the CONFIG1 register
0 = Device is running from the internal oscillator (HFINTOSC or LFINTOSC)
bit 2
IOFS: HFINTOSC Frequency Stable bit
1 = HFINTOSC frequency is stable
0 = HFINTOSC frequency is not stable
bit 1-0
SCS<1:0>: System Clock Select bits
1x = Internal oscillator block
01 = Secondary (Timer1) oscillator
00 = Primary clock (determined by CONFIG1H[FOSC<3:0>]).
Note 1:
2:
3:
Reset state depends on state of the IESO Configuration bit.
Source selected by the INTSRC bit of the OSCTUNE register, see text.
Default output frequency of HFINTOSC on Reset.
 2010 Microchip Technology Inc.
DS41303G-page 29
PIC18F2XK20/4XK20
2.3
Clock Source Modes
Clock Source modes can be classified as external or
internal.
• External Clock modes rely on external circuitry for
the clock source. Examples are: Clock modules
(EC mode), quartz crystal resonators or ceramic
resonators (LP, XT and HS modes) and ResistorCapacitor (RC mode) circuits.
• Internal clock sources are contained internally
within the Oscillator block. The Oscillator block
has two internal oscillators: the 16 MHz HighFrequency Internal Oscillator (HFINTOSC) and
the 31 kHz Low-Frequency Internal Oscillator
(LFINTOSC).
External Clock Modes
2.4.1
OSCILLATOR START-UP TIMER
(OST)
When the Oscillator module is configured for LP, XT or
HS modes, the Oscillator Start-up Timer (OST) counts
1024 oscillations from OSC1. This occurs following a
Power-on Reset (POR) and when the Power-up Timer
(PWRT) has expired (if configured), or a wake-up from
Sleep. During this time, the program counter does not
increment and program execution is suspended. The
OST ensures that the oscillator circuit, using a quartz
crystal resonator or ceramic resonator, has started and
is providing a stable system clock to the Oscillator
module. When switching between clock sources, a
delay is required to allow the new clock to stabilize.
These oscillator delays are shown in Table 2-1.
The system clock can be selected between external or
internal clock sources via the System Clock Select
(SCS<1:0>) bits of the OSCCON register. See
Section 2.9 “Clock Switching” for additional information.
TABLE 2-1:
2.4
In order to minimize latency between external oscillator
start-up and code execution, the Two-Speed Clock
Start-up mode can be selected (see Section 2.10
“Two-Speed Clock Start-up Mode”).
OSCILLATOR DELAY EXAMPLES
Switch From
Switch To
Frequency
Sleep/POR
LFINTOSC
HFINTOSC
31 kHz
250 kHz to 16 MHz
Oscillator Delay
Oscillator Warm-Up Delay (TWARM)
Sleep/POR
EC, RC
DC – 64 MHz
2 instruction cycles
LFINTOSC (31 kHz)
EC, RC
DC – 64 MHz
1 cycle of each
Sleep/POR
LP, XT, HS
32 kHz to 40 MHz
1024 Clock Cycles (OST)
Sleep/POR
HSPLL
32 MHz to 64 MHz
1024 Clock Cycles (OST) + 2 ms
LFINTOSC (31 kHz)
HFINTOSC
250 kHz to 16 MHz
1 s (approx.)
2.4.2
EC MODE
The External Clock (EC) mode allows an externally
generated logic level as the system clock source. When
operating in this mode, an external clock source is
connected to the OSC1 input and the OSC2 is available
for general purpose I/O. Figure 2-2 shows the pin
connections for EC mode.
The Oscillator Start-up Timer (OST) is disabled when
EC mode is selected. Therefore, there is no delay in
operation after a Power-on Reset (POR) or wake-up
from Sleep. Because the PIC® MCU design is fully
static, stopping the external clock input will have the
effect of halting the device while leaving all data intact.
Upon restarting the external clock, the device will
resume operation as if no time had elapsed.
DS41303G-page 30
FIGURE 2-2:
EXTERNAL CLOCK (EC)
MODE OPERATION
OSC1/CLKIN
Clock from
Ext. System
PIC® MCU
I/O
Note 1:
OSC2/CLKOUT(1)
Alternate pin functions are listed in
Section 1.0 “Device Overview”.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
2.4.3
LP, XT, HS MODES
The LP, XT and HS modes support the use of quartz
crystal resonators or ceramic resonators connected to
OSC1 and OSC2 (Figure 2-3). The mode selects a low,
medium or high gain setting of the internal inverteramplifier to support various resonator types and speed.
LP Oscillator mode selects the lowest gain setting of the
internal inverter-amplifier. LP mode current consumption
is the least of the three modes. This mode is best suited
to drive resonators with a low drive level specification, for
example, tuning fork type crystals.
Note 1: Quartz crystal characteristics vary according
to type, package and manufacturer. The
user should consult the manufacturer data
sheets for specifications and recommended
application.
2: Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.
3: For oscillator design assistance, reference
the following Microchip Applications Notes:
• AN826, “Crystal Oscillator Basics and
Crystal Selection for rfPIC® and PIC®
Devices” (DS00826)
• AN849, “Basic PIC® Oscillator Design”
(DS00849)
• AN943, “Practical PIC® Oscillator
Analysis and Design” (DS00943)
• AN949, “Making Your Oscillator Work”
(DS00949)
XT Oscillator mode selects the intermediate gain
setting of the internal inverter-amplifier. XT mode
current consumption is the medium of the three modes.
This mode is best suited to drive resonators with a
medium drive level specification.
HS Oscillator mode selects the highest gain setting of the
internal inverter-amplifier. HS mode current consumption
is the highest of the three modes. This mode is best
suited for resonators that require a high drive setting.
Figure 2-3 and Figure 2-4 show typical circuits for
quartz crystal and ceramic resonators, respectively.
FIGURE 2-3:
FIGURE 2-4:
CERAMIC RESONATOR
OPERATION
(XT OR HS MODE)
QUARTZ CRYSTAL
OPERATION (LP, XT OR
HS MODE)
PIC® MCU
OSC1/CLKIN
PIC® MCU
C1
To Internal
Logic
OSC1/CLKIN
C1
To Internal
Logic
Quartz
Crystal
C2
RS(1)
RF(2)
RP(3)
RF(2)
Sleep
Sleep
C2 Ceramic
RS(1)
Resonator
OSC2/CLKOUT
OSC2/CLKOUT
Note 1: A series resistor (RS) may be required for
ceramic resonators with low drive level.
Note 1:
A series resistor (RS) may be required for
quartz crystals with low drive level.
2: The value of RF varies with the Oscillator mode
selected (typically between 2 M to 10 M.
2:
The value of RF varies with the Oscillator mode
selected (typically between 2 M to 10 M.
3: An additional parallel feedback resistor (RP)
may be required for proper ceramic resonator
operation.
 2010 Microchip Technology Inc.
DS41303G-page 31
PIC18F2XK20/4XK20
2.4.4
EXTERNAL RC MODES
2.5
The external Resistor-Capacitor (RC) modes support
the use of an external RC circuit. This allows the
designer maximum flexibility in frequency choice while
keeping costs to a minimum when clock accuracy is not
required. There are two modes: RC and RCIO.
2.4.4.1
The Oscillator module has two independent, internal
oscillators that can be configured or selected as the
system clock source.
1.
RC Mode
In RC mode, the RC circuit connects to OSC1. OSC2/
CLKOUT outputs the RC oscillator frequency divided
by 4. This signal may be used to provide a clock for
external circuitry, synchronization, calibration, test or
other application requirements. Figure 2-5 shows the
external RC mode connections.
FIGURE 2-5:
EXTERNAL RC MODES
VDD
PIC® MCU
Internal Clock Modes
2.
The HFINTOSC (High-Frequency Internal
Oscillator) is factory calibrated and operates at
16 MHz. The frequency of the HFINTOSC can
be user-adjusted via software using the
OSCTUNE register (Register 2-2).
The LFINTOSC (Low-Frequency Internal
Oscillator) operates at 31 kHz.
The system clock speed can be selected via software
using the Internal Oscillator Frequency Select bits
IRCF<2:0> of the OSCCON register.
The system clock can be selected between external or
internal clock sources via the System Clock Selection
(SCS<1:0>) bits of the OSCCON register. See
Section 2.9 “Clock Switching” for more information.
REXT
OSC1/CLKIN
Internal
Clock
CEXT
VSS
FOSC/4 or
I/O(2)
OSC2/CLKOUT(1)
Recommended values: 10 k  REXT  100 k
CEXT > 20 pF
Note 1:
2:
2.4.4.2
Alternate pin functions are listed in
Section 1.0 “Device Overview”.
Output depends upon RC or RCIO clock mode.
RCIO Mode
In RCIO mode, the RC circuit is connected to OSC1.
OSC2 becomes an additional general purpose I/O pin.
The RC oscillator frequency is a function of the supply
voltage, the resistor (REXT) and capacitor (CEXT) values
and the operating temperature. Other factors affecting
the oscillator frequency are:
• input threshold voltage variation
• component tolerances
• packaging variations in capacitance
The user also needs to take into account variation due
to tolerance of external RC components used.
2.5.1
INTOSC AND INTOSCIO MODES
The INTOSC and INTOSCIO modes configure the
internal oscillators as the primary clock source. The
FOSC<3:0> bits in the CONFIG1H Configuration
register determine which mode is selected. See
Section 23.0 “Special Features of the CPU” for more
information.
In INTOSC mode, OSC1/CLKIN is available for general
purpose I/O. OSC2/CLKOUT outputs the selected
internal oscillator frequency divided by 4. The CLKOUT
signal may be used to provide a clock for external
circuitry, synchronization, calibration, test or other
application requirements.
In INTOSCIO mode, OSC1/CLKIN and OSC2/CLKOUT
are available for general purpose I/O.
2.5.2
HFINTOSC
The output of the HFINTOSC connects to a postscaler
and multiplexer (see Figure 2-1). One of eight
frequencies can be selected via software using the
IRCF<2:0> bits of the OSCCON register. See
Section 2.5.4 “Frequency Select Bits (IRCF)” for
more information.
The HFINTOSC is enabled when:
• SCS1 = 1 and IRCF<2:0>  000
• SCS1 = 1 and IRCF<2:0> = 000 and INTSRC = 1
• IESO bit of CONFIG1H = 1 enabling Two-Speed
Start-up.
• FCMEM bit of CONFIG1H = 1 enabling TwoSpeed Start-up and Fail-Safe mode.
• FOSC<3:0> of CONFIG1H selects the internal
oscillator as the primary clock
The HF Internal Oscillator (IOFS) bit of the OSCCON
register indicates whether the HFINTOSC is stable or not.
DS41303G-page 32
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
2.5.2.1
OSCTUNE Register
The HFINTOSC is factory calibrated but can be
adjusted in software by writing to the TUN<5:0> bits of
the OSCTUNE register (Register 2-2).
The default value of the TUN<5:0> is ‘000000’. The
value is a 6-bit two’s complement number.
When the OSCTUNE register is modified, the
HFINTOSC frequency will begin shifting to the new
frequency. Code execution continues during this shift.
There is no indication that the shift has occurred.
OSCTUNE does not affect the LFINTOSC frequency.
Operation of features that depend on the LFINTOSC
clock source frequency, such as the Power-up Timer
REGISTER 2-2:
(PWRT), Watchdog Timer (WDT), Fail-Safe Clock Monitor (FSCM) and peripherals, are not affected by the
change in frequency.
The OSCTUNE register also implements the INTSRC
and PLLEN bits, which control certain features of the
internal oscillator block.
The INTSRC bit allows users to select which internal
oscillator provides the clock source when the 31 kHz
frequency option is selected. This is covered in greater
detail in Section 2.2.3 “Low Frequency Selection”.
The PLLEN bit controls the operation of the frequency
multiplier, PLL, in internal oscillator modes. For more
details about the function of the PLLEN bit see
Section 2.6.2 “PLL in HFINTOSC Modes”
OSCTUNE: OSCILLATOR TUNING REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
INTSRC
PLLEN(1)
TUN5
TUN4
TUN3
TUN2
TUN1
TUN0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
INTSRC: Internal Oscillator Low-Frequency Source Select bit
1 = 31.25 kHz device clock derived from 16 MHz HFINTOSC source (divide-by-512 enabled)
0 = 31 kHz device clock derived directly from LFINTOSC internal oscillator
bit 6
PLLEN: Frequency Multiplier PLL for HFINTOSC Enable bit(1)
1 = PLL enabled for HFINTOSC (8 MHz and 16 MHz only)
0 = PLL disabled
bit 5-0
TUN<5:0>: Frequency Tuning bits
011111 = Maximum frequency
011110 =
•••
000001 =
000000 = Oscillator module is running at the factory calibrated frequency.
111111 =
•••
100000 = Minimum frequency
Note 1:
The PLLEN bit is active only when the HFINTOSC is the primary clock source (FOSC<2:0> = 100X) and
the selected frequency is 8 MHz or 16 MHz. Otherwise, the PLLEN bit is unavailable and always reads ‘0’.
 2010 Microchip Technology Inc.
DS41303G-page 33
PIC18F2XK20/4XK20
2.5.3
LFINTOSC
The Low-Frequency Internal Oscillator (LFINTOSC) is
a 31 kHz internal clock source.
The output of the LFINTOSC connects to internal
oscillator block frequency selection multiplexer (see
Figure 2-1). Select 31 kHz, via software, using the
IRCF<2:0> bits of the OSCCON register and the
INTSRC bit of the OSCTUNE register. See
Section 2.5.4 “Frequency Select Bits (IRCF)” for
more information. The LFINTOSC is also the frequency
for the Power-up Timer (PWRT), Watchdog Timer
(WDT) and Fail-Safe Clock Monitor (FSCM).
The LFINTOSC is enabled when any of the following
are enabled:
• IRCF<2:0> bits of the OSCCON register = 000 and
INTSRC bit of the OSCTUNE register = 0
• Power-up Timer (PWRT)
• Watchdog Timer (WDT)
• Fail-Safe Clock Monitor (FSCM)
2.5.4
FREQUENCY SELECT BITS (IRCF)
The output of the 16 MHz HFINTOSC and 31 kHz
LFINTOSC connects to a postscaler and multiplexer
(see Figure 2-1). The Internal Oscillator Frequency
Select bits IRCF<2:0> of the OSCCON register select
the output frequency of the internal oscillators. One of
eight frequencies can be selected via software:
•
•
•
•
•
•
•
•
16 MHz
8 MHz
4 MHz
2 MHz
1 MHz (Default after Reset)
500 kHz
250 kHz
31 kHz (LFINTOSC or HFINTOSC/512)
Note:
Following any Reset, the IRCF<2:0> bits of
the OSCCON register are set to ‘011’ and
the frequency selection is set to 1 MHz.
The user can modify the IRCF bits to
select a different frequency.
2.5.5
HFINTOSC FREQUENCY DRIFT
The factory calibrates the internal oscillator block output
(HFINTOSC) for 16 MHz. However, this frequency may
drift as VDD or temperature changes, which can affect the
controller operation in a variety of ways. It is possible to
adjust the HFINTOSC frequency by modifying the value
of the TUN<5:0> bits in the OSCTUNE register. This has
no effect on the LFINTOSC clock source frequency.
Tuning the HFINTOSC source requires knowing when to
make the adjustment, in which direction it should be
made and in some cases, how large a change is
needed. Three possible compensation techniques are
discussed in the following sections, however other techniques may be used.
2.5.5.1
Compensating with the USART
An adjustment may be required when the USART
begins to generate framing errors or receives data with
errors while in Asynchronous mode. Framing errors
indicate that the device clock frequency is too high; to
adjust for this, decrement the value in OSCTUNE to
reduce the clock frequency. On the other hand, errors
in data may suggest that the clock speed is too low; to
compensate, increment OSCTUNE to increase the
clock frequency.
2.5.5.2
Compensating with the Timers
This technique compares device clock speed to some
reference clock. Two timers may be used; one timer is
clocked by the peripheral clock, while the other is
clocked by a fixed reference source, such as the
Timer1 oscillator.
Both timers are cleared, but the timer clocked by the
reference generates interrupts. When an interrupt
occurs, the internally clocked timer is read and both
timers are cleared. If the internally clocked timer value
is greater than expected, then the internal oscillator
block is running too fast. To adjust for this, decrement
the OSCTUNE register.
2.5.5.3
Compensating with the CCP Module
in Capture Mode
A CCP module can use free running Timer1 (or Timer3),
clocked by the internal oscillator block and an external
event with a known period (i.e., AC power frequency).
The time of the first event is captured in the
CCPRxH:CCPRxL registers and is recorded for use later.
When the second event causes a capture, the time of the
first event is subtracted from the time of the second
event. Since the period of the external event is known,
the time difference between events can be calculated.
If the measured time is much greater than the calculated time, the internal oscillator block is running too
fast; to compensate, decrement the OSCTUNE register.
If the measured time is much less than the calculated
time, the internal oscillator block is running too slow; to
compensate, increment the OSCTUNE register.
DS41303G-page 34
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
2.6
2.6.2
PLL Frequency Multiplier
A Phase Locked Loop (PLL) circuit is provided as an
option for users who wish to use a lower frequency
oscillator circuit or to clock the device up to its highest
rated frequency from the crystal oscillator. This may be
useful for customers who are concerned with EMI due
to high-frequency crystals or users who require higher
clock speeds from an internal oscillator. There are
three conditions when the PLL can be used:
• When the primary clock is HSPLL
• When the primary clock is HFINTOSC and the
selected frequency is 16 MHz
• When the primary clock is HFINTOSC and the
selected frequency is 8 MHz
2.6.1
HSPLL OSCILLATOR MODE
The HSPLL mode makes use of the HS mode oscillator
for frequencies up to 16 MHz. A PLL then multiplies the
oscillator output frequency by 4 to produce an internal
clock frequency up to 64 MHz. The PLLEN bit of the
OSCTUNE register is active only when the HFINTOSC
is the primary clock and is not available in HSPLL oscillator mode.
PLL IN HFINTOSC MODES
The 4x frequency multiplier can be used with the internal oscillator block to produce faster device clock
speeds than are normally possible with an internal
oscillator. When enabled, the PLL produces a clock
speed of up to 64 MHz.
Unlike HSPLL mode, the PLL is controlled through
software. The PLLEN control bit of the OSCTUNE
register is used to enable or disable the PLL operation
when the HFINTOSC is used.
The PLL is available when the device is configured to
use the internal oscillator block as its primary clock
source (FOSC<3:0> = 1001 or 1000). Additionally, the
PLL will only function when the selected output frequency is either 8 MHz or 16 MHz (OSCCON<6:4> =
111 or 110). If both of these conditions are not met, the
PLL is disabled.
The PLLEN control bit is only functional in those internal oscillator modes where the PLL is available. In all
other modes, it is forced to ‘0’ and is effectively
unavailable.
The PLL is only available to the primary oscillator when
the FOSC<3:0> Configuration bits are programmed for
HSPLL mode (= 0110).
FIGURE 2-6:
PLL BLOCK DIAGRAM
(HS MODE)
HS Oscillator Enable
PLL Enable
(from Configuration Register 1H)
OSC2
HS Mode
OSC1 Crystal
Osc
FIN
Phase
Comparator
FOUT
Loop
Filter
VCO
MUX
4
 2010 Microchip Technology Inc.
SYSCLK
DS41303G-page 35
PIC18F2XK20/4XK20
2.7
Effects of Power-Managed Modes
on the Various Clock Sources
For more information about the modes discussed in this
section see Section 3.0 “Power-Managed Modes”. A
quick reference list is also available in Table 3-1.
When PRI_IDLE mode is selected, the designated primary oscillator continues to run without interruption.
For all other power-managed modes, the oscillator
using the OSC1 pin is disabled. The OSC1 pin (and
OSC2 pin, if used by the oscillator) will stop oscillating.
In secondary clock modes (SEC_RUN and
SEC_IDLE), the Timer1 oscillator is operating and
providing the device clock. The Timer1 oscillator may
also run in all power-managed modes if required to
clock Timer1 or Timer3.
In internal oscillator modes (INTOSC_RUN and
INTOSC_IDLE), the internal oscillator block provides
the device clock source. The 31 kHz LFINTOSC output
can be used directly to provide the clock and may be
enabled to support various special features, regardless
of the power-managed mode (see Section 23.2
“Watchdog Timer (WDT)”, Section 2.10 “TwoSpeed Clock Start-up Mode” and Section 2.11 “FailSafe Clock Monitor” for more information on WDT,
Fail-Safe Clock Monitor and Two-Speed Start-up). The
HFINTOSC output at 16 MHz may be used directly to
clock the device or may be divided down by the postscaler. The HFINTOSC output is disabled if the clock is
provided directly from the LFINTOSC output.
If the Sleep mode is selected, all clock sources are
stopped. Since all the transistor switching currents
have been stopped, Sleep mode achieves the lowest
current consumption of the device (only leakage
currents).
Enabling any on-chip feature that will operate during
Sleep will increase the current consumed during Sleep.
The LFINTOSC is required to support WDT operation.
The Timer1 oscillator may be operating to support a
real-time clock. Other features may be operating that
do not require a device clock source (i.e., SSP slave,
PSP, INTn pins and others). Peripherals that may add
significant current consumption are listed in
Section 26.8 “DC Characteristics”.
TABLE 2-2:
2.8
Power-up Delays
Power-up delays are controlled by two timers, so that
no external Reset circuitry is required for most applications. The delays ensure that the device is kept in
Reset until the device power supply is stable under normal circumstances and the primary clock is operating
and stable. For additional information on power-up
delays, see Section 4.5 “Device Reset Timers”.
The first timer is the Power-up Timer (PWRT), which
provides a fixed delay on power-up (parameter 33,
Table 26-10). It is enabled by clearing (= 0) the
PWRTEN Configuration bit.
The second timer is the Oscillator Start-up Timer
(OST), intended to keep the chip in Reset until the
crystal oscillator is stable (LP, XT and HS modes). The
OST does this by counting 1024 oscillator cycles
before allowing the oscillator to clock the device.
When the HSPLL Oscillator mode is selected, the
device is kept in Reset for an additional 2 ms, following
the HS mode OST delay, so the PLL can lock to the
incoming clock frequency.
There is a delay of interval TCSD (parameter 38,
Table 26-10), following POR, while the controller
becomes ready to execute instructions. This delay runs
concurrently with any other delays. This may be the
only delay that occurs when any of the EC, RC or INTIO
modes are used as the primary clock source.
When the HFINTOSC is selected as the primary clock,
the main system clock can be delayed until the
HFINTOSC is stable. This is user selectable by the
HFOFST bit of the CONFIG3H Configuration register.
When the HFOFST bit is cleared the main system clock
is delayed until the HFINTOSC is stable. When the
HFOFST bit is set the main system clock starts immediately. In either case the IOFS bit of the OSCCON register can be read to determine whether the HFINTOSC
is operating and stable.
OSC1 AND OSC2 PIN STATES IN SLEEP MODE
OSC Mode
OSC1 Pin
OSC2 Pin
RC, INTOSC
Floating, external resistor should pull high
At logic low (clock/4 output)
RCIO
Floating, external resistor should pull high
Configured as PORTA, bit 6
INTOSCIO
Configured as PORTA, bit 7
Configured as PORTA, bit 6
ECIO
Floating, pulled by external clock
Configured as PORTA, bit 6
EC
Floating, pulled by external clock
At logic low (clock/4 output)
LP, XT, HS and HSPLL
Feedback inverter disabled at quiescent
voltage level
Feedback inverter disabled at quiescent
voltage level
Note:
See Table 4-2 in Section 4.0 “Reset” for time-outs due to Sleep and MCLR Reset.
DS41303G-page 36
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
2.9
Clock Switching
The system clock source can be switched between
external and internal clock sources via software using
the System Clock Select (SCS<1:0>) bits of the
OSCCON register.
PIC18F2XK20/4XK20 devices contain circuitry to prevent clock “glitches” when switching between clock
sources. A short pause in the device clock occurs during the clock switch. The length of this pause is the sum
of two cycles of the old clock source and three to four
cycles of the new clock source. This formula assumes
that the new clock source is stable.
Clock transitions are discussed in greater detail in
Section 3.1.2 “Entering Power-Managed Modes”.
2.9.1
• When SCS<1:0> = 00, the system clock source is
determined by configuration of the FOSC<2:0>
bits in the CONFIG1H Configuration register.
• When SCS<1:0> = 10, the system clock source is
chosen by the internal oscillator frequency
selected by the INTSRC bit of the OSCTUNE
register and the IRCF<2:0> bits of the OSCCON
register.
• When SCS<1:0> = 01, the system clock source is
the 32.768 kHz secondary oscillator shared with
Timer1.
After a Reset, the SCS<1:0> bits of the OSCCON
register are always cleared.
2.9.2
Any automatic clock switch, which may
occur from Two-Speed Start-up or Fail-Safe
Clock Monitor, does not update the
SCS<1:0> bits of the OSCCON register.
The user can monitor the T1RUN bit of the
T1CON register and the IOFS and OSTS
bits of the OSCCON register to determine
the current system clock source.
CLOCK SWITCH TIMING
When switching between one oscillator and another,
the new oscillator may not be operating which saves
power (see Figure 2-7). If this is the case, there is a
delay after the SCS<1:0> bits of the OSCCON register
are modified before the frequency change takes place.
The OSTS and IOFS bits of the OSCCON register will
reflect the current active status of the external and
HFINTOSC oscillators. The timing of a frequency
selection is as follows:
1.
2.
3.
SYSTEM CLOCK SELECT
(SCS<1:0>) BITS
The System Clock Select (SCS<1:0>) bits of the
OSCCON register select the system clock source that
is used for the CPU and peripherals.
Note:
2.9.3
4.
5.
6.
7.
SCS<1:0> bits of the OSCCON register are modified.
The old clock continues to operate until the new
clock is ready.
Clock switch circuitry waits for two consecutive
rising edges of the old clock after the new clock
ready signal goes true.
The system clock is held low starting at the next
falling edge of the old clock.
Clock switch circuitry waits for an additional two
rising edges of the new clock.
On the next falling edge of the new clock the low
hold on the system clock is released and new
clock is switched in as the system clock.
Clock switch is complete.
See Figure 2-1 for more details.
If the HFINTOSC is the source of both the old and new
frequency, there is no start-up delay before the new
frequency is active. This is because the old and new
frequencies are derived from the HFINTOSC via the
postscaler and multiplexer.
Start-up delay specifications are located in
Section 26.0 “Electrical Characteristics”, under AC
Specifications (Oscillator Module).
OSCILLATOR START-UP TIME-OUT
STATUS (OSTS) BIT
The Oscillator Start-up Time-out Status (OSTS) bit of
the OSCCON register indicates whether the system
clock is running from the external clock source, as
defined by the FOSC<3:0> bits in the CONFIG1H
Configuration register, or from the internal clock
source. In particular, when the primary oscillator is the
source of the primary clock, OSTS indicates that the
Oscillator Start-up Timer (OST) has timed out for LP,
XT or HS modes.
 2010 Microchip Technology Inc.
DS41303G-page 37
PIC18F2XK20/4XK20
2.10
Two-Speed Clock Start-up Mode
Two-Speed Start-up mode provides additional power
savings by minimizing the latency between external
oscillator start-up and code execution. In applications
that make heavy use of the Sleep mode, Two-Speed
Start-up will remove the external oscillator start-up
time from the time spent awake and can reduce the
overall power consumption of the device.
This mode allows the application to wake-up from
Sleep, perform a few instructions using the HFINTOSC
as the clock source and go back to Sleep without
waiting for the primary oscillator to become stable.
Note:
Executing a SLEEP instruction will abort
the oscillator start-up time and will cause
the OSTS bit of the OSCCON register to
remain clear.
When the Oscillator module is configured for LP, XT or
HS modes, the Oscillator Start-up Timer (OST) is
enabled (see Section 2.4.1 “Oscillator Start-up Timer
(OST)”). The OST will suspend program execution until
1024 oscillations are counted. Two-Speed Start-up
mode minimizes the delay in code execution by
operating from the internal oscillator as the OST is
counting. When the OST count reaches 1024 and the
OSTS bit of the OSCCON register is set, program
execution switches to the external oscillator.
2.10.1
2.10.2
1.
2.
3.
4.
5.
6.
TWO-SPEED START-UP
SEQUENCE
Wake-up from Power-on Reset or Sleep.
Instructions begin executing by the internal
oscillator at the frequency set in the IRCF<2:0>
bits of the OSCCON register.
OST enabled to count 1024 external clock
cycles.
OST timed out. External clock is ready.
OSTS is set.
Clock switch finishes according to FIGURE 2-7:
“Clock Switch Timing”
2.10.3
CHECKING TWO-SPEED CLOCK
STATUS
Checking the state of the OSTS bit of the OSCCON
register will confirm if the microcontroller is running
from the external clock source, as defined by the
FOSC<2:0> bits in CONFIG1H Configuration register,
or the internal oscillator. OSTS = 0 when the external
oscillator is not ready, which indicates that the system
is running from the internal oscillator.
TWO-SPEED START-UP MODE
CONFIGURATION
Two-Speed Start-up mode is enabled when all of the
following settings are configured as noted:
• Two-Speed Start-up mode is enabled by setting
the IESO of the CONFIG1H Configuration register
is set. Fail-Safe mode (FCMEM = 1) also enables
two-speed by default.
• SCS<1:0> (of the OSCCON register) = 00.
• FOSC<2:0> bits of the CONFIG1H Configuration
register are configured for LP, XT or HS mode.
Two-Speed Start-up mode becomes active after:
• Power-on Reset (POR) and, if enabled, after
Power-up Timer (PWRT) has expired, or
• Wake-up from Sleep.
If the external clock oscillator is configured to be
anything other than LP, XT or HS mode, then TwoSpeed Start-up is disabled. This is because the
external clock oscillator does not require any
stabilization time after POR or an exit from Sleep.
DS41303G-page 38
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 2-7:
High Speed
CLOCK SWITCH TIMING
Low Speed
Old Clock
Start-up Time(1)
Clock Sync
Running
New Clock
New Clk Ready
IRCF <2:0> Select Old
Select New
System Clock
Low Speed
High Speed
Old Clock
Start-up Time(1)
Clock Sync
Running
New Clock
New Clk Ready
IRCF <2:0> Select Old
Select New
System Clock
Note 1: Start-up time includes TOST (1024 TOSC) for external clocks, plus TPLL (approx. 2 ms) for HSPLL mode.
 2010 Microchip Technology Inc.
DS41303G-page 39
PIC18F2XK20/4XK20
2.11
2.11.3
Fail-Safe Clock Monitor
The Fail-Safe Clock Monitor (FSCM) allows the device
to continue operating should the external oscillator fail.
The FSCM can detect oscillator failure any time after
the Oscillator Start-up Timer (OST) has expired. The
FSCM is enabled by setting the FCMEN bit in the
CONFIG1H Configuration register. The FSCM is
applicable to all external oscillator modes (LP, XT, HS,
EC, RC and RCIO).
FIGURE 2-8:
FSCM BLOCK DIAGRAM
Clock Monitor
Latch
External
Clock
S
LFINTOSC
Oscillator
÷ 64
31 kHz
(~32 s)
488 Hz
(~2 ms)
R
Q
Sample Clock
2.11.1
Clock
Failure
Detected
FAIL-SAFE DETECTION
The FSCM module detects a failed oscillator by
comparing the external oscillator to the FSCM sample
clock. The sample clock is generated by dividing the
LFINTOSC by 64. See Figure 2-8. Inside the fail
detector block is a latch. The external clock sets the
latch on each falling edge of the external clock. The
sample clock clears the latch on each rising edge of the
sample clock. A failure is detected when an entire halfcycle of the sample clock elapses before the primary
clock goes low.
2.11.2
The Fail-Safe condition is cleared by either one of the
following:
• Any Reset
• By toggling the SCS1 bit of the OSCCON register
Both of these conditions restart the OST. While the
OST is running, the device continues to operate from
the INTOSC selected in OSCCON. When the OST
times out, the Fail-Safe condition is cleared and the
device automatically switches over to the external clock
source. The Fail-Safe condition need not be cleared
before the OSCFIF flag is cleared.
2.11.4
Q
FAIL-SAFE CONDITION CLEARING
RESET OR WAKE-UP FROM SLEEP
The FSCM is designed to detect an oscillator failure
after the Oscillator Start-up Timer (OST) has expired.
The OST is used after waking up from Sleep and after
any type of Reset. The OST is not used with the EC or
RC Clock modes so that the FSCM will be active as
soon as the Reset or wake-up has completed. When
the FSCM is enabled, the Two-Speed Start-up is also
enabled. Therefore, the device will always be executing
code while the OST is operating.
Note:
Due to the wide range of oscillator start-up
times, the Fail-Safe circuit is not active
during oscillator start-up (i.e., after exiting
Reset or Sleep). After an appropriate
amount of time, the user should check the
OSTS bit of the OSCCON register to verify
the oscillator start-up and that the system
clock
switchover
has
successfully
completed.
FAIL-SAFE OPERATION
When the external clock fails, the FSCM switches the
device clock to an internal clock source and sets the bit
flag OSCFIF of the PIR2 register. The OSCFIF flag will
generate an interrupt if the OSCFIE bit of the PIE2
register is also set. The device firmware can then take
steps to mitigate the problems that may arise from a
failed clock. The system clock will continue to be
sourced from the internal clock source until the device
firmware successfully restarts the external oscillator
and switches back to external operation. An automatic
transition back to the failed clock source will not occur.
The internal clock source chosen by the FSCM is
determined by the IRCF<2:0> bits of the OSCCON
register. This allows the internal oscillator to be
configured before a failure occurs.
DS41303G-page 40
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 2-9:
FSCM TIMING DIAGRAM
Sample Clock
Oscillator
Failure
System
Clock
Output
Clock Monitor Output
(Q)
Failure
Detected
OSCFIF
Test
Note:
TABLE 2-3:
Test
Test
The system clock is normally at a much higher frequency than the sample clock. The relative frequencies in
this example have been chosen for clarity.
SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets(1)
CONFIG1H
IESO
FCMEN
—
—
FOSC3
FOSC2
FOSC1
FOSC0
—
—
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
0000 000x
0000 000x
OSCCON
IDLEN
IRCF2
IRCF1
IRCF0
OSTS
IOFS
SCS1
SCS0
0011 q000
0011 q000
OSCTUNE
INTSRC
PLLEN
TUN5
TUN4
TUN3
TUN2
TUN1
TUN0
0000 0000
000u uuuu
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
0000 0000
0000 0000
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
0000 0000
0000 0000
IPR2
OSCFIP
—
—
—
—
—
—
—
1111 1111
1111 1111
INTCON
Legend:
Note 1:
GIE/GIEH PEIE/GIEL TMR0IE
x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by oscillators.
Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation.
 2010 Microchip Technology Inc.
DS41303G-page 41
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 42
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
3.0
POWER-MANAGED MODES
3.1.1
CLOCK SOURCES
The SCS<1:0> bits allow the selection of one of three
clock sources for power-managed modes. They are:
PIC18F2XK20/4XK20 devices offer a total of seven
operating modes for more efficient power management. These modes provide a variety of options for
selective power conservation in applications where
resources may be limited (i.e., battery-powered
devices).
• the primary clock, as defined by the FOSC<3:0>
Configuration bits
• the secondary clock (the Timer1 oscillator)
• the internal oscillator block
There are three categories of power-managed modes:
3.1.2
• Run modes
• Idle modes
• Sleep mode
Switching from one power-managed mode to another
begins by loading the OSCCON register. The
SCS<1:0> bits select the clock source and determine
which Run or Idle mode is to be used. Changing these
bits causes an immediate switch to the new clock
source, assuming that it is running. The switch may
also be subject to clock transition delays. These are
discussed in Section 3.1.3 “Clock Transitions and
Status Indicators” and subsequent sections.
These categories define which portions of the device
are clocked and sometimes, what speed. The Run and
Idle modes may use any of the three available clock
sources (primary, secondary or internal oscillator
block); the Sleep mode does not use a clock source.
The power-managed modes include several powersaving features offered on previous PIC® microcontroller
devices. One is the clock switching feature which allows
the controller to use the Timer1 oscillator in place of the
primary oscillator. Also included is the Sleep mode,
offered by all PIC® microcontroller devices, where all
device clocks are stopped.
3.1
ENTERING POWER-MANAGED
MODES
Entry to the power-managed Idle or Sleep modes is
triggered by the execution of a SLEEP instruction. The
actual mode that results depends on the status of the
IDLEN bit of the OSCCON register.
Depending on the current mode and the mode being
switched to, a change to a power-managed mode does
not always require setting all of these bits. Many
transitions may be done by changing the oscillator select
bits, or changing the IDLEN bit, prior to issuing a SLEEP
instruction. If the IDLEN bit is already configured
correctly, it may only be necessary to perform a SLEEP
instruction to switch to the desired mode.
Selecting Power-Managed Modes
Selecting a power-managed mode requires two
decisions:
• Whether or not the CPU is to be clocked
• The selection of a clock source
The IDLEN bit of the OSCCON register controls CPU
clocking, while the SCS<1:0> bits of the OSCCON
register select the clock source. The individual modes,
bit settings, clock sources and affected modules are
summarized in Table 3-1.
TABLE 3-1:
POWER-MANAGED MODES
OSCCON Bits
Mode
Module Clocking
Available Clock and Oscillator Source
IDLEN(1)
SCS<1:0>
CPU
Peripherals
0
N/A
Off
Off
PRI_RUN
N/A
00
Clocked
Clocked
SEC_RUN
N/A
01
Clocked
Clocked
Secondary – Timer1 Oscillator
RC_RUN
N/A
1x
Clocked
Clocked
Internal Oscillator Block(2)
PRI_IDLE
1
00
Off
Clocked
Primary – LP, XT, HS, HSPLL, RC, EC
SEC_IDLE
1
01
Off
Clocked
Secondary – Timer1 Oscillator
RC_IDLE
1
1x
Off
Clocked
Internal Oscillator Block(2)
Sleep
Note 1:
2:
None – All clocks are disabled
Primary – LP, XT, HS, HSPLL, RC, EC and
Internal Oscillator Block(2).
This is the normal full power execution mode.
IDLEN reflects its value when the SLEEP instruction is executed.
Includes HFINTOSC and HFINTOSC postscaler, as well as the LFINTOSC source.
 2010 Microchip Technology Inc.
DS41303G-page 43
PIC18F2XK20/4XK20
3.1.3
CLOCK TRANSITIONS AND
STATUS INDICATORS
The length of the transition between clock sources is
the sum of:
• Start-up time of the new clock
• Two and one half cycles of the old clock source
• Two and one half cycles of the new clock
Three flag bits indicate the current clock source and its
status. They are:
• OSTS (of the OSCCON register)
• IOFS (of the OSCCON register)
• T1RUN (of the T1CON register)
In general, only one of these bits will be set while in a
given power-managed mode. Table 3-2 shows the relationship of the flags to the active main system clock
source.
TABLE 3-2:
SYSTEM CLOCK INDICATORS
OSTS IOFS T1RUN
Main System Clock Source
1
0
0
Primary Oscillator
0
1
0
HFINTOSC
0
0
1
Secondary Oscillator
1
1
0
HFINTOSC as primary clock
0
LFINTOSC or
HFINTOSC is not yet stable
0
0
.
Note 1: Executing a SLEEP instruction does not
necessarily place the device into Sleep
mode. It acts as the trigger to place the
controller into either the Sleep mode or
one of the Idle modes, depending on the
setting of the IDLEN bit.
3.1.4
MULTIPLE FUNCTIONS OF THE
SLEEP COMMAND
The power-managed mode that is invoked with the
SLEEP instruction is determined by the setting of the
IDLEN bit of the OSCCON register at the time the
instruction is executed. All clocks stop and minimum
power is consumed when SLEEP is executed with the
IDLEN bit cleared. The system clock continues to supply a clock to the peripherals but is disconnected from
the CPU when SLEEP is executed with the IDLEN bit
set.
DS41303G-page 44
3.2
Run Modes
In the Run modes, clocks to both the core and
peripherals are active. The difference between these
modes is the clock source.
3.2.1
PRI_RUN MODE
The PRI_RUN mode is the normal, full power execution
mode of the microcontroller. This is also the default
mode upon a device Reset, unless Two-Speed Startup is enabled (see Section 2.10 “Two-Speed Clock
Start-up Mode” for details). In this mode, the OSTS bit
is set. The IOFS bit will be set if the HFINTOSC is the
primary clock source and the oscillator is stable (see
Section 2.2 “Oscillator Control”).
3.2.2
SEC_RUN MODE
The SEC_RUN mode is the mode compatible to the
“clock switching” feature offered in other PIC18
devices. In this mode, the CPU and peripherals are
clocked from the Timer1 oscillator. This gives users the
option of lower power consumption while still using a
high accuracy clock source.
SEC_RUN mode is entered by setting the SCS<1:0>
bits to ‘01’. When SEC_RUN mode is active all of the
following are true:
• The main clock source is switched to the Timer1
oscillator
• Primary oscillator is shut down
• T1RUN bit of the T1CON register is set
• OSTS bit is cleared.
Note:
The Timer1 oscillator should already be
running prior to entering SEC_RUN mode.
If the T1OSCEN bit is not set when the
SCS<1:0> bits are set to ‘01’, entry to
SEC_RUN mode will not occur until
T1OSCEN bit is set and Timer1 oscillator
is ready.
On transitions from SEC_RUN mode to PRI_RUN, the
peripherals and CPU continue to be clocked from the
Timer1 oscillator while the primary clock is started.
When the primary clock becomes ready, a clock switch
back to the primary clock occurs (see Figure 2-7).
When the clock switch is complete, the T1RUN bit is
cleared, the OSTS bit is set and the primary clock is
providing the main system clock. The Timer1 oscillator
continues to run as long as the T1OSCEN bit is set.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
3.2.3
RC_RUN MODE
In RC_RUN mode, the CPU and peripherals are
clocked from the internal oscillator block using one of
the selections from the HFINTOSC multiplexer. In this
mode, the primary oscillator is shut down. RC_RUN
mode provides the best power conservation of all the
Run modes when the LFINTOSC is the main clock
source. It works well for user applications which are not
highly timing sensitive or do not require high-speed
clocks at all times.
If the primary clock source is the internal oscillator
block (either LFINTOSC or HFINTOSC), there are no
distinguishable differences between PRI_RUN and
RC_RUN modes during execution. However, a clock
switch delay will occur during entry to and exit from
RC_RUN mode. Therefore, if the primary clock source
is the internal oscillator block, the use of RC_RUN
mode is not recommended. See 2.9.3 “Clock Switch
Timing” for details about clock switching.
RC_RUN mode is entered by setting the SCS1 bit to
‘1’. The SCS0 bit can be either ‘0’ or ‘1’ but should be
‘0’ to maintain software compatibility with future
devices. When the clock source is switched from the
primary oscillator to the HFINTOSC multiplexer, the primary oscillator is shut down and the OSTS bit is
cleared. The IRCF bits may be modified at any time to
immediately change the clock speed.
On transitions from RC_RUN mode to PRI_RUN mode,
the device continues to be clocked from the internal
oscillator block while the primary oscillator is started.
When the primary oscillator becomes ready, a clock
switch to the primary clock occurs. When the clock
switch is complete, the IOFS bit is cleared, the OSTS
bit is set and the primary oscillator is providing the main
system clock. The HFINTOSC will continue to run if any
of the conditions noted in Section 2.5.2 “HFINTOSC”
are met. The LFINTOSC source will continue to run if
any of the conditions noted in Section 2.5.3 “LFINTOSC” are met.
3.3
Sleep Mode
The Power-Managed Sleep mode in the PIC18F2XK20/
4XK20 devices is identical to the legacy Sleep mode
offered in all other PIC® microcontroller devices. It is
entered by clearing the IDLEN bit (the default state on
device Reset) and executing the SLEEP instruction.
This shuts down the selected oscillator (Figure 3-1). All
clock source Status bits are cleared.
Entering the Sleep mode from any other mode does not
require a clock switch. This is because no clocks are
needed once the controller has entered Sleep. If the
WDT is selected, the LFINTOSC source will continue to
operate. If the Timer1 oscillator is enabled, it will also
continue to run.
When a wake event occurs in Sleep mode (by interrupt,
Reset or WDT time-out), the device will not be clocked
until the clock source selected by the SCS<1:0> bits
becomes ready (see Figure 3-2), or it will be clocked
from the internal oscillator block if either the Two-Speed
Start-up or the Fail-Safe Clock Monitor are enabled
(see Section 23.0 “Special Features of the CPU”). In
either case, the OSTS bit is set when the primary clock
is providing the device clocks. The IDLEN and SCS bits
are not affected by the wake-up.
3.4
Idle Modes
The Idle modes allow the controller’s CPU to be
selectively shut down while the peripherals continue to
operate. Selecting a particular Idle mode allows users
to further manage power consumption.
If the IDLEN bit is set to a ‘1’ when a SLEEP instruction is
executed, the peripherals will be clocked from the clock
source selected by the SCS<1:0> bits; however, the CPU
will not be clocked. The clock source Status bits are not
affected. Setting IDLEN and executing a SLEEP instruction provides a quick method of switching from a given
Run mode to its corresponding Idle mode.
If the WDT is selected, the LFINTOSC source will continue to operate. If the Timer1 oscillator is enabled, it
will also continue to run.
Since the CPU is not executing instructions, the only
exits from any of the Idle modes are by interrupt, WDT
time-out, or a Reset. When a wake event occurs, CPU
execution is delayed by an interval of TCSD
(parameter 38, Table 26-10) while it becomes ready to
execute code. When the CPU begins executing code,
it resumes with the same clock source for the current
Idle mode. For example, when waking from RC_IDLE
mode, the internal oscillator block will clock the CPU
and peripherals (in other words, RC_RUN mode). The
IDLEN and SCS bits are not affected by the wake-up.
While in any Idle mode or the Sleep mode, a WDT
time-out will result in a WDT wake-up to the Run mode
currently specified by the SCS<1:0> bits.
 2010 Microchip Technology Inc.
DS41303G-page 45
PIC18F2XK20/4XK20
FIGURE 3-1:
TRANSITION TIMING FOR ENTRY TO SLEEP MODE
Q1 Q2 Q3 Q4 Q1
OSC1
CPU
Clock
Peripheral
Clock
Sleep
Program
Counter
PC
FIGURE 3-2:
PC + 2
TRANSITION TIMING FOR WAKE FROM SLEEP (HSPLL)
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q1
OSC1
PLL Clock
Output
TOST(1)
TPLL(1)
CPU Clock
Peripheral
Clock
Program
Counter
PC
Wake Event
PC + 2
PC + 4
PC + 6
OSTS bit set
Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
DS41303G-page 46
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
3.4.1
PRI_IDLE MODE
3.4.2
This mode is unique among the three low-power Idle
modes, in that it does not disable the primary device
clock. For timing sensitive applications, this allows for
the fastest resumption of device operation with its more
accurate primary clock source, since the clock source
does not have to “warm-up” or transition from another
oscillator.
PRI_IDLE mode is entered from PRI_RUN mode by
setting the IDLEN bit and executing a SLEEP instruction. If the device is in another Run mode, set IDLEN
first, then clear the SCS bits and execute SLEEP.
Although the CPU is disabled, the peripherals continue
to be clocked from the primary clock source specified
by the FOSC<3:0> Configuration bits. The OSTS bit
remains set (see Figure 3.3).
In SEC_IDLE mode, the CPU is disabled but the
peripherals continue to be clocked from the Timer1
oscillator. This mode is entered from SEC_RUN by setting the IDLEN bit and executing a SLEEP instruction. If
the device is in another Run mode, set the IDLEN bit
first, then set the SCS<1:0> bits to ‘01’ and execute
SLEEP. When the clock source is switched to the
Timer1 oscillator, the primary oscillator is shut down,
the OSTS bit is cleared and the T1RUN bit is set.
When a wake event occurs, the peripherals continue to
be clocked from the Timer1 oscillator. After an interval
of TCSD following the wake event, the CPU begins executing code being clocked by the Timer1 oscillator. The
IDLEN and SCS bits are not affected by the wake-up;
the Timer1 oscillator continues to run (see Figure 3-4).
When a wake event occurs, the CPU is clocked from the
primary clock source. A delay of interval TCSD is
required between the wake event and when code
execution starts. This is required to allow the CPU to
become ready to execute instructions. After the wakeup, the OSTS bit remains set. The IDLEN and SCS bits
are not affected by the wake-up (see Figure 3-4).
FIGURE 3-3:
SEC_IDLE MODE
Note:
The Timer1 oscillator should already be
running prior to entering SEC_IDLE mode.
If the T1OSCEN bit is not set when the
SLEEP instruction is executed, the main
system clock will continue to operate in the
previously selected mode and the corresponding IDLE mode will be entered (i.e.,
PRI_IDLE or RC_IDLE).
TRANSITION TIMING FOR ENTRY TO IDLE MODE
Q1
Q3
Q2
Q4
Q1
OSC1
CPU Clock
Peripheral
Clock
Program
Counter
PC
FIGURE 3-4:
PC + 2
TRANSITION TIMING FOR WAKE FROM IDLE TO RUN MODE
Q1
Q2
Q3
Q4
OSC1
TCSD
CPU Clock
Peripheral
Clock
Program
Counter
PC
Wake Event
 2010 Microchip Technology Inc.
DS41303G-page 47
PIC18F2XK20/4XK20
3.4.3
RC_IDLE MODE
In RC_IDLE mode, the CPU is disabled but the peripherals continue to be clocked from the internal oscillator
block from the HFINTOSC multiplexer output. This
mode allows for controllable power conservation during
Idle periods.
From RC_RUN, this mode is entered by setting the
IDLEN bit and executing a SLEEP instruction. If the
device is in another Run mode, first set IDLEN, then set
the SCS1 bit and execute SLEEP. It is recommended
that SCS0 also be cleared, although its value is
ignored, to maintain software compatibility with future
devices. The HFINTOSC multiplexer may be used to
select a higher clock frequency by modifying the IRCF
bits before executing the SLEEP instruction. When the
clock source is switched to the HFINTOSC multiplexer,
the primary oscillator is shut down and the OSTS bit is
cleared.
If the IRCF bits are set to any non-zero value, or the
INTSRC bit is set, the HFINTOSC output is enabled.
The IOFS bit becomes set, after the HFINTOSC output
becomes stable, after an interval of TIOBST
(parameter 39, Table 26-10). Clocks to the peripherals
continue while the HFINTOSC source stabilizes. If the
IRCF bits were previously at a non-zero value, or
INTSRC was set before the SLEEP instruction was executed and the HFINTOSC source was already stable,
the IOFS bit will remain set. If the IRCF bits and
INTSRC are all clear, the HFINTOSC output will not be
enabled, the IOFS bit will remain clear and there will be
no indication of the current clock source.
When a wake event occurs, the peripherals continue to
be clocked from the HFINTOSC multiplexer output.
After a delay of TCSD following the wake event, the
CPU begins executing code being clocked by the
HFINTOSC multiplexer. The IDLEN and SCS bits are
not affected by the wake-up. The LFINTOSC source
will continue to run if either the WDT or the Fail-Safe
Clock Monitor is enabled.
3.5
Exiting Idle and Sleep Modes
An exit from Sleep mode or any of the Idle modes is
triggered by any one of the following:
• an interrupt
• a Reset
• a watchdog time-out
This section discusses the triggers that cause exits
from power-managed modes. The clocking subsystem
actions are discussed in each of the power-managed
modes (see Section 3.2 “Run Modes”, Section 3.3
“Sleep Mode” and Section 3.4 “Idle Modes”).
DS41303G-page 48
3.5.1
EXIT BY INTERRUPT
Any of the available interrupt sources can cause the
device to exit from an Idle mode or the Sleep mode to
a Run mode. To enable this functionality, an interrupt
source must be enabled by setting its enable bit in one
of the INTCON or PIE registers. The PEIE bIt must also
be set If the desired interrupt enable bit is in a PIE register. The exit sequence is initiated when the corresponding interrupt flag bit is set.
The instruction immediately following the SLEEP
instruction is executed on all exits by interrupt from Idle
or Sleep modes. Code execution then branches to the
interrupt vector if the GIE/GIEH bit of the INTCON register is set, otherwise code execution continues without
branching (see Section 9.0 “Interrupts”).
A fixed delay of interval TCSD following the wake event
is required when leaving Sleep and Idle modes. This
delay is required for the CPU to prepare for execution.
Instruction execution resumes on the first clock cycle
following this delay.
3.5.2
EXIT BY WDT TIME-OUT
A WDT time-out will cause different actions depending
on which power-managed mode the device is in when
the time-out occurs.
If the device is not executing code (all Idle modes and
Sleep mode), the time-out will result in an exit from the
power-managed mode (see Section 3.2 “Run
Modes” and Section 3.3 “Sleep Mode”). If the device
is executing code (all Run modes), the time-out will
result in a WDT Reset (see Section 23.2 “Watchdog
Timer (WDT)”).
The WDT timer and postscaler are cleared by any one
of the following:
• executing a SLEEP instruction
• executing a CLRWDT instruction
• the loss of the currently selected clock source
when the Fail-Safe Clock Monitor is enabled
• modifying the IRCF bits in the OSCCON register
when the internal oscillator block is the device
clock source
3.5.3
EXIT BY RESET
Exiting Sleep and Idle modes by Reset causes code
execution to restart at address 0. See Section 4.0
“Reset” for more details.
The exit delay time from Reset to the start of code
execution depends on both the clock sources before
and after the wake-up and the type of oscillator. Exit
delays are summarized in Table 3-3.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
3.5.4
EXIT WITHOUT AN OSCILLATOR
START-UP DELAY
Certain exits from power-managed modes do not
invoke the OST at all. There are two cases:
• PRI_IDLE mode, where the primary clock source
is not stopped and
• the primary clock source is not any of the LP, XT,
HS or HSPLL modes.
TABLE 3-3:
In these instances, the primary clock source either
does not require an oscillator start-up delay since it is
already running (PRI_IDLE), or normally does not
require an oscillator start-up delay (RC, EC, INTOSC,
and INTOSCIO modes). However, a fixed delay of
interval TCSD following the wake event is still required
when leaving Sleep and Idle modes to allow the CPU
to prepare for execution. Instruction execution resumes
on the first clock cycle following this delay.
EXIT DELAY ON WAKE-UP BY RESET FROM SLEEP MODE OR ANY IDLE MODE
(BY CLOCK SOURCES)
Clock Source
before Wake-up
Clock Source
after Wake-up
Exit Delay
Clock Ready Status
Bit (OSCCON)
LP, XT, HS
Primary Device Clock
(PRI_IDLE mode)
HSPLL
EC, RC
TCSD(1)
HFINTOSC(2)
T1OSC or LFINTOSC(1)
HFINTOSC(2)
None
(Sleep mode)
2:
3:
4:
IOFS
LP, XT, HS
TOST(3)
HSPLL
TOST + tPLL(3)
OSTS
EC, RC
HFINTOSC(1)
TCSD(1)
TIOBST(4)
IOFS
LP, XT, HS
TOST(4)
HSPLL
TOST + tPLL(3)
EC, RC
TCSD(1)
HFINTOSC(1)
None
LP, XT, HS
TOST(3)
HSPLL
TOST + tPLL(3)
OSTS
EC, RC
TCSD(1)
TIOBST(4)
IOFS
HFINTOSC(1)
Note 1:
OSTS
OSTS
IOFS
TCSD (parameter
38) is a required delay when waking from Sleep and all Idle modes and runs concurrently
with any other required delays (see Section 3.4 “Idle Modes”). On Reset, HFINTOSC defaults to 1 MHz.
Includes both the HFINTOSC 16 MHz source and postscaler derived frequencies.
TOST is the Oscillator Start-up Timer (parameter 32). tPLL is the PLL Lock-out Timer (parameter F12).
Execution continues during the HFINTOSC stabilization period, TIOBST (parameter 39).
 2010 Microchip Technology Inc.
DS41303G-page 49
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 50
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
4.0
RESET
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 4-1.
The PIC18F2XK20/4XK20 devices
between various kinds of Reset:
a)
b)
c)
d)
e)
f)
g)
h)
differentiate
Power-on Reset (POR)
MCLR Reset during normal operation
MCLR Reset during power-managed modes
Watchdog Timer (WDT) Reset (during
execution)
Programmable Brown-out Reset (BOR)
RESET Instruction
Stack Full Reset
Stack Underflow Reset
This section discusses Resets generated by MCLR,
POR and BOR and covers the operation of the various
start-up timers. Stack Reset events are covered in
Section 5.1.2.4 “Stack Full and Underflow Resets”.
WDT Resets are covered in Section 23.2 “Watchdog
Timer (WDT)”.
FIGURE 4-1:
4.1
RCON Register
Device Reset events are tracked through the RCON
register (Register 4-1). The lower five bits of the register indicate that a specific Reset event has occurred. In
most cases, these bits can only be cleared by the event
and must be set by the application after the event. The
state of these flag bits, taken together, can be read to
indicate the type of Reset that just occurred. This is
described in more detail in Section 4.6 “Reset State
of Registers”.
The RCON register also has control bits for setting
interrupt priority (IPEN) and software control of the
BOR (SBOREN). Interrupt priority is discussed in
Section 9.0 “Interrupts”. BOR is covered in
Section 4.4 “Brown-out Reset (BOR)”.
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
RESET
Instruction
Stack Full/Underflow Reset
Stack
Pointer
External Reset
MCLRE
MCLR
( )_IDLE
Sleep
WDT
Time-out
VDD
Detect
POR
VDD
Brown-out
Reset
BOREN
S
OST/PWRT
OST(2) 1024 Cycles
10-bit Ripple Counter
Chip_Reset
R
Q
OSC1
32 s
LFINTOSC
PWRT(2) 65.5 ms
11-bit Ripple Counter
Enable PWRT
Enable OST(1)
Note 1:
2:
See Table 4-2 for time-out situations.
PWRT and OST counters are reset by POR and BOR. See Sections 4.3 and 4.4.
 2010 Microchip Technology Inc.
DS41303G-page 51
PIC18F2XK20/4XK20
REGISTER 4-1:
R/W-0
IPEN
RCON: RESET CONTROL REGISTER
R/W-1
SBOREN
U-0
(1)
—
R/W-1
RI
R-1
TO
R-1
R/W-0
PD
(2)
R/W-0
POR
bit 7
BOR
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
IPEN: Interrupt Priority Enable bit
1 = Enable priority levels on interrupts
0 = Disable priority levels on interrupts (PIC16CXXX Compatibility mode)
bit 6
SBOREN: BOR Software Enable bit(1)
If BOREN<1:0> = 01:
1 = BOR is enabled
0 = BOR is disabled
If BOREN<1:0> = 00, 10 or 11:
Bit is disabled and read as ‘0’.
bit 5
Unimplemented: Read as ‘0’
bit 4
RI: RESET Instruction Flag bit
1 = The RESET instruction was not executed (set by firmware or Power-on Reset)
0 = The RESET instruction was executed causing a device Reset (must be set in firmware after a
code-executed Reset occurs)
bit 3
TO: Watchdog Time-out Flag bit
1 = Set by power-up, CLRWDT instruction or SLEEP instruction
0 = A WDT time-out occurred
bit 2
PD: Power-down Detection Flag bit
1 = Set by power-up or by the CLRWDT instruction
0 = Set by execution of the SLEEP instruction
bit 1
POR: Power-on Reset Status bit(2)
1 = No Power-on Reset occurred
0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs)
bit 0
BOR: Brown-out Reset Status bit(3)
1 = A Brown-out Reset has not occurred (set by firmware only)
0 = A Brown-out Reset occurred (must be set by firmware after a POR or Brown-out Reset occurs)
Note 1:
2:
3:
When CONFIG2L[2:1] = 01, then the SBOREN Reset state is ‘1’; otherwise, it is ‘0’.
The actual Reset value of POR is determined by the type of device Reset. See the notes following this
register and Section 4.6 “Reset State of Registers” for additional information.
See Table 4-3.
Note 1: Brown-out Reset is indicated when BOR is ‘0’ and POR is ‘1’ (assuming that both POR and BOR were set
to ‘1’ by firmware immediately after POR).
2: It is recommended that the POR bit be set after a Power-on Reset has been detected so that subsequent
Power-on Resets may be detected.
DS41303G-page 52
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
4.2
Master Clear (MCLR)
The MCLR pin provides a method for triggering an
external Reset of the device. A Reset is generated by
holding the pin low. These devices have a noise filter in
the MCLR Reset path which detects and ignores small
pulses.
FIGURE 4-2:
4.3
PIC® MCU
D
To take advantage of the POR circuitry, tie the MCLR
pin through a resistor to VDD. This will eliminate external RC components usually needed to create a
Power-on Reset delay. A minimum rise rate for VDD is
specified (parameter D004). For a slow rise time, see
Figure 4-2.
R
R1
MCLR
C
Note 1:
External Power-on Reset circuit is required
only if the VDD power-up slope is too slow.
The diode D helps discharge the capacitor
quickly when VDD powers down.
2:
15 k < R < 40 k is recommended to make
sure that the voltage drop across R does not
violate the device’s electrical specification.
3:
R1  1 k will limit any current flowing into
MCLR from external capacitor C, in the event
of MCLR/VPP pin breakdown, due to
Electrostatic Discharge (ESD) or Electrical
Overstress (EOS).
Power-on Reset (POR)
A Power-on Reset pulse is generated on-chip
whenever VDD rises above a certain threshold. This
allows the device to start in the initialized state when
VDD is adequate for operation.
VDD
VDD
The MCLR pin is not driven low by any internal Resets,
including the WDT.
In PIC18F2XK20/4XK20 devices, the MCLR input can
be disabled with the MCLRE Configuration bit. When
MCLR is disabled, the pin becomes a digital input. See
Section 10.6 “PORTE, TRISE and LATE Registers”
for more information.
EXTERNAL POWER-ON
RESET CIRCUIT (FOR
SLOW VDD POWER-UP)
When the device starts normal operation (i.e., exits the
Reset condition), device operating parameters (voltage, frequency, temperature, etc.) must be met to
ensure proper operation. If these conditions are not
met, the device must be held in Reset until the operating conditions are met.
POR events are captured by the POR bit of the RCON
register. The state of the bit is set to ‘0’ whenever a
POR occurs; it does not change for any other Reset
event. POR is not reset to ‘1’ by any hardware event.
To capture multiple events, the user must manually set
the bit to ‘1’ by software following any POR.
 2010 Microchip Technology Inc.
DS41303G-page 53
PIC18F2XK20/4XK20
4.4
Brown-out Reset (BOR)
PIC18F2XK20/4XK20 devices implement a BOR circuit
that provides the user with a number of configuration and
power-saving options. The BOR is controlled by the
BORV<1:0> and BOREN<1:0> bits of the CONFIG2L
Configuration register. There are a total of four BOR
configurations which are summarized in Table 4-1.
The BOR threshold is set by the BORV<1:0> bits. If
BOR is enabled (any values of BOREN<1:0>, except
‘00’), any drop of VDD below VBOR (parameter D005)
for greater than TBOR (parameter 35) will reset the
device. A Reset may or may not occur if VDD falls below
VBOR for less than TBOR. The chip will remain in
Brown-out Reset until VDD rises above VBOR.
If the Power-up Timer is enabled, it will be invoked after
VDD rises above VBOR; it then will keep the chip in
Reset for an additional time delay, TPWRT
(parameter 33). If VDD drops below VBOR while the
Power-up Timer is running, the chip will go back into a
Brown-out Reset and the Power-up Timer will be
initialized. Once VDD rises above VBOR, the Power-up
Timer will execute the additional time delay.
BOR and the Power-on Timer (PWRT) are
independently configured. Enabling BOR Reset does
not automatically enable the PWRT.
The BOR circuit has an output that feeds into the POR
circuit and rearms the POR within the operating range
of the BOR. This early rearming of the POR ensures
that the device will remain in Reset in the event that VDD
falls below the operating range of the BOR circuitry.
4.4.1
DETECTING BOR
When BOR is enabled, the BOR bit always resets to ‘0’
on any BOR or POR event. This makes it difficult to
determine if a BOR event has occurred just by reading
the state of BOR alone. A more reliable method is to
simultaneously check the state of both POR and BOR.
This assumes that the POR and BOR bits are reset to
‘1’ by software immediately after any POR event. If
BOR is ‘0’ while POR is ‘1’, it can be reliably assumed
that a BOR event has occurred.
TABLE 4-1:
4.4.2
SOFTWARE ENABLED BOR
When BOREN<1:0> = 01, the BOR can be enabled or
disabled by the user in software. This is done with the
SBOREN control bit of the RCON register. Setting
SBOREN enables the BOR to function as previously
described. Clearing SBOREN disables the BOR
entirely. The SBOREN bit operates only in this mode;
otherwise it is read as ‘0’.
Placing the BOR under software control gives the user
the additional flexibility of tailoring the application to its
environment without having to reprogram the device to
change BOR configuration. It also allows the user to
tailor device power consumption in software by
eliminating the incremental current that the BOR
consumes. While the BOR current is typically very small,
it may have some impact in low-power applications.
Note:
4.4.3
Even when BOR is under software control,
the BOR Reset voltage level is still set by
the BORV<1:0> Configuration bits. It
cannot be changed by software.
DISABLING BOR IN SLEEP MODE
When BOREN<1:0> = 10, the BOR remains under
hardware control and operates as previously
described. Whenever the device enters Sleep mode,
however, the BOR is automatically disabled. When the
device returns to any other operating mode, BOR is
automatically re-enabled.
This mode allows for applications to recover from
brown-out situations, while actively executing code,
when the device requires BOR protection the most. At
the same time, it saves additional power in Sleep mode
by eliminating the small incremental BOR current.
4.4.4
MINIMUM BOR ENABLE TIME
Enabling the BOR also enables the Fixed Voltage
Reference (FVR) when no other peripheral requiring the
FVR is active. The BOR becomes active only after the
FVR stabilizes. Therefore, to ensure BOR protection,
the FVR settling time must be considered when
enabling the BOR in software or when the BOR is
automatically enabled after waking from Sleep. If the
BOR is disabled, in software or by reentering Sleep
before the FVR stabilizes, the BOR circuit will not sense
a BOR condition. The FVRST bit of the CVRCON2
register can be used to determine FVR stability.
BOR CONFIGURATIONS
BOR Configuration
BOREN1
BOREN0
Status of
SBOREN
(RCON<6>)
0
0
Unavailable
0
1
Available
1
0
Unavailable
BOR enabled by hardware in Run and Idle modes, disabled during
Sleep mode.
1
1
Unavailable
BOR enabled by hardware; must be disabled by reprogramming the Configuration bits.
DS41303G-page 54
BOR Operation
BOR disabled; must be enabled by reprogramming the Configuration bits.
BOR enabled by software; operation controlled by SBOREN.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
4.5
Device Reset Timers
PIC18F2XK20/4XK20 devices incorporate three
separate on-chip timers that help regulate the
Power-on Reset process. Their main function is to
ensure that the device clock is stable before code is
executed. These timers are:
• Power-up Timer (PWRT)
• Oscillator Start-up Timer (OST)
• PLL Lock Time-out
4.5.1
POWER-UP TIMER (PWRT)
The
Power-up
Timer
(PWRT)
of
PIC18F2XK20/4XK20 devices is an 11-bit counter
which uses the LFINTOSC source as the clock input.
This yields an approximate time interval of
2048 x 32 s = 65.6 ms. While the PWRT is counting,
the device is held in Reset.
The power-up time delay depends on the LFINTOSC
clock and will vary from chip-to-chip due to temperature
and process variation. See DC parameter 33 for
details.
The PWRT is enabled by clearing the PWRTEN
Configuration bit.
4.5.2
OSCILLATOR START-UP TIMER
(OST)
The Oscillator Start-up Timer (OST) provides a 1024
oscillator cycle (from OSC1 input) delay after the
PWRT delay is over (parameter 33). This ensures that
the crystal oscillator or resonator has started and
stabilized.
TABLE 4-2:
4.5.3
PLL LOCK TIME-OUT
With the PLL enabled in its PLL mode, the time-out
sequence following a Power-on Reset is slightly
different from other oscillator modes. A separate timer
is used to provide a fixed time-out that is sufficient for
the PLL to lock to the main oscillator frequency. This
PLL lock time-out (TPLL) is typically 2 ms and follows
the oscillator start-up time-out.
4.5.4
TIME-OUT SEQUENCE
On power-up, the time-out sequence is as follows:
1.
2.
After the POR pulse has cleared, PWRT time-out
is invoked (if enabled).
Then, the OST is activated.
The total time-out will vary based on oscillator
configuration and the status of the PWRT. Figure 4-3,
Figure 4-4, Figure 4-5, Figure 4-6 and Figure 4-7 all
depict time-out sequences on power-up, with the
Power-up Timer enabled and the device operating in
HS Oscillator mode. Figures 4-3 through 4-6 also
apply to devices operating in XT or LP modes. For
devices in RC mode and with the PWRT disabled, on
the other hand, there will be no time-out at all.
Since the time-outs occur from the POR pulse, if MCLR
is kept low long enough, all time-outs will expire, after
which, bringing MCLR high will allow program
execution to begin immediately (Figure 4-5). This is
useful for testing purposes or to synchronize more than
one PIC18FXXK20 device operating in parallel.
TIME-OUT IN VARIOUS SITUATIONS
Power-up(2) and Brown-out
Oscillator
Configuration
HSPLL
The OST time-out is invoked only for XT, LP, HS and
HSPLL modes and only on Power-on Reset, or on exit
from all power-managed modes that stop the external
oscillator.
PWRTEN = 0
66
ms(1)
+ 1024 TOSC + 2
ms(2)
PWRTEN = 1
Exit from
Power-Managed Mode
1024 TOSC + 2 ms(2)
1024 TOSC + 2 ms(2)
HS, XT, LP
66 ms(1) + 1024 TOSC
1024 TOSC
1024 TOSC
EC, ECIO
66 ms(1)
—
—
RC, RCIO
ms(1)
—
—
(1)
—
—
INTIO1, INTIO2
66
66 ms
Note 1: 66 ms (65.5 ms) is the nominal Power-up Timer (PWRT) delay.
2: 2 ms is the nominal time required for the PLL to lock.
 2010 Microchip Technology Inc.
DS41303G-page 55
PIC18F2XK20/4XK20
FIGURE 4-3:
TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD, VDD RISE < TPWRT)
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
TOST
OST TIME-OUT
INTERNAL RESET
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1
FIGURE 4-4:
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
TOST
OST TIME-OUT
INTERNAL RESET
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2
FIGURE 4-5:
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
TOST
OST TIME-OUT
INTERNAL RESET
DS41303G-page 56
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 4-6:
SLOW RISE TIME (MCLR TIED TO VDD, VDD RISE > TPWRT)
5V
VDD
0V
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
TOST
OST TIME-OUT
INTERNAL RESET
FIGURE 4-7:
TIME-OUT SEQUENCE ON POR W/PLL ENABLED (MCLR TIED TO VDD)
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
OST TIME-OUT
TOST
TPLL
PLL TIME-OUT
INTERNAL RESET
Note:
TOST = 1024 clock cycles.
TPLL  2 ms max. First three stages of the PWRT timer.
 2010 Microchip Technology Inc.
DS41303G-page 57
PIC18F2XK20/4XK20
4.6
Reset State of Registers
Some registers are unaffected by a Reset. Their status
is unknown on POR and unchanged by all other
Resets. All other registers are forced to a “Reset state”
depending on the type of Reset that occurred.
Table 4-4 describes the Reset states for all of the
Special Function Registers. These are categorized by
Power-on and Brown-out Resets, Master Clear and
WDT Resets and WDT wake-ups.
Most registers are not affected by a WDT wake-up,
since this is viewed as the resumption of normal
operation. Status bits from the RCON register, RI, TO,
PD, POR and BOR, are set or cleared differently in
different Reset situations, as indicated in Table 4-3.
These bits are used by software to determine the
nature of the Reset.
TABLE 4-3:
STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION
FOR RCON REGISTER
Condition
Program
Counter
RCON Register
SBOREN
RI
TO
PD
STKPTR Register
POR BOR STKFUL
STKUNF
Power-on Reset
0000h
1
1
1
1
0
0
0
0
RESET Instruction
0000h
u(2)
0
u
u
u
u
u
u
Brown-out Reset
0000h
(2)
u
1
1
1
u
0
u
u
MCLR during Power-Managed
Run Modes
0000h
u(2)
u
1
u
u
u
u
u
MCLR during Power-Managed
Idle Modes and Sleep Mode
0000h
u(2)
u
1
0
u
u
u
u
WDT Time-out during Full Power
or Power-Managed Run Mode
0000h
u(2)
u
0
u
u
u
u
u
MCLR during Full Power
Execution
0000h
u(2)
u
u
u
u
u
u
u
Stack Full Reset (STVREN = 1)
0000h
u(2)
u
u
u
u
u
1
u
Stack Underflow Reset
(STVREN = 1)
0000h
u(2)
u
u
u
u
u
u
1
Stack Underflow Error (not an
actual Reset, STVREN = 0)
0000h
u(2)
u
u
u
u
u
u
1
WDT Time-out during
Power-Managed Idle or Sleep
Modes
PC + 2
u(2)
u
0
0
u
u
u
u
PC + 2(1)
u(2)
u
u
0
u
u
u
u
Interrupt Exit from
Power-Managed Modes
Legend: u = unchanged
Note 1: When the wake-up is due to an interrupt and the GIEH or GIEL bits are set, the PC is loaded with the
interrupt vector (008h or 0018h).
2: Reset state is ‘1’ for SBOREN and unchanged for all other Resets when software BOR is enabled
(BOREN<1:0> Configuration bits = 01). Otherwise, the Reset state is ‘0’.
DS41303G-page 58
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS
Applicable Devices
Power-on Reset,
Brown-out Reset
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
TOSU
PIC18F2XK20 PIC18F4XK20
---0 0000
---0 0000
---0 uuuu(3)
TOSH
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu(3)
TOSL
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu(3)
STKPTR
PIC18F2XK20 PIC18F4XK20
00-0 0000
uu-0 0000
uu-u uuuu(3)
PCLATU
PIC18F2XK20 PIC18F4XK20
---0 0000
---0 0000
---u uuuu
PCLATH
Register
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
PCL
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
PC + 2(2)
TBLPTRU
PIC18F2XK20 PIC18F4XK20
--00 0000
--00 0000
--uu uuuu
TBLPTRH
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
TBLPTRL
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
TABLAT
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
PRODH
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
PRODL
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
INTCON
PIC18F2XK20 PIC18F4XK20
0000 000x
0000 000u
uuuu uuuu(1)
INTCON2
PIC18F2XK20 PIC18F4XK20
1111 -1-1
1111 -1-1
uuuu -u-u(1)
INTCON3
PIC18F2XK20 PIC18F4XK20
11-0 0-00
11-0 0-00
uu-u u-uu(1)
INDF0
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
POSTINC0
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
POSTDEC0
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
PREINC0
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
PLUSW0
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
FSR0H
PIC18F2XK20 PIC18F4XK20
---- 0000
---- 0000
---- uuuu
FSR0L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
WREG
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
INDF1
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
POSTINC1
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
POSTDEC1
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
PREINC1
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
PLUSW1
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
Legend:
Note 1:
2:
3:
4:
5:
6:
u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
See Table 4-3 for Reset value for specific condition.
Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as
PORTA pins, they are disabled and read ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
 2010 Microchip Technology Inc.
DS41303G-page 59
PIC18F2XK20/4XK20
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Applicable Devices
Power-on Reset,
Brown-out Reset
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
FSR1H
PIC18F2XK20 PIC18F4XK20
---- 0000
---- 0000
---- uuuu
FSR1L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
BSR
Register
PIC18F2XK20 PIC18F4XK20
---- 0000
---- 0000
---- uuuu
INDF2
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
POSTINC2
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
POSTDEC2
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
PREINC2
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
PLUSW2
PIC18F2XK20 PIC18F4XK20
N/A
N/A
N/A
FSR2H
PIC18F2XK20 PIC18F4XK20
---- 0000
---- 0000
---- uuuu
FSR2L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
STATUS
PIC18F2XK20 PIC18F4XK20
---x xxxx
---u uuuu
---u uuuu
TMR0H
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
TMR0L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
T0CON
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
OSCCON
PIC18F2XK20 PIC18F4XK20
0011 qq00
0011 qq00
uuuu uuuu
HLVDCON
PIC18F2XK20 PIC18F4XK20
0-00 0101
0-00 0101
u-uu uuuu
WDTCON
PIC18F2XK20 PIC18F4XK20
---- ---0
---- ---0
---- ---u
PIC18F2XK20 PIC18F4XK20
0q-1 11q0
0u-q qquu
uu-u qquu
RCON
(4)
TMR1H
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
TMR1L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
T1CON
PIC18F2XK20 PIC18F4XK20
0000 0000
u0uu uuuu
uuuu uuuu
TMR2
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
PR2
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
1111 1111
T2CON
PIC18F2XK20 PIC18F4XK20
-000 0000
-000 0000
-uuu uuuu
SSPBUF
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
SSPADD
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
SSPSTAT
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
SSPCON1
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
SSPCON2
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
Legend:
Note 1:
2:
3:
4:
5:
6:
u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
See Table 4-3 for Reset value for specific condition.
Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as
PORTA pins, they are disabled and read ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
DS41303G-page 60
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Applicable Devices
Power-on Reset,
Brown-out Reset
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
ADRESH
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
ADRESL
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
ADCON0
Register
PIC18F2XK20 PIC18F4XK20
--00 0000
--00 0000
--uu uuuu
ADCON1
PIC18F2XK20 PIC18F4XK20
--00 0qqq
--00 0qqq
--uu uuuu
ADCON2
PIC18F2XK20 PIC18F4XK20
0-00 0000
0-00 0000
u-uu uuuu
CCPR1H
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
CCPR1L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
CCP1CON
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
CCPR2H
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
CCPR2L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
CCP2CON
PIC18F2XK20 PIC18F4XK20
--00 0000
--00 0000
--uu uuuu
PSTRCON
PIC18F2XK20 PIC18F4XK20
---0 0001
---0 0001
---u uuuu
BAUDCON
PIC18F2XK20 PIC18F4XK20
0100 0-00
0100 0-00
uuuu u-uu
PWM1CON
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
ECCP1AS
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
CVRCON
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
CVRCON2
PIC18F2XK20 PIC18F4XK20
00-- ----
00-- ----
uu-- ----
TMR3H
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
TMR3L
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
T3CON
PIC18F2XK20 PIC18F4XK20
0000 0000
uuuu uuuu
uuuu uuuu
SPBRGH
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
SPBRG
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
RCREG
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
TXREG
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
TXSTA
PIC18F2XK20 PIC18F4XK20
0000 0010
0000 0010
uuuu uuuu
RCSTA
PIC18F2XK20 PIC18F4XK20
0000 000x
0000 000x
uuuu uuuu
EEADR
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
EEADRH
PIC18F26K20
PIC18F46K20
---- --00
---- --00
---- --uu
EEDATA
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
EECON2
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
0000 0000
PIC18F2XK20 PIC18F4XK20
xx-0 x000
uu-0 u000
uu-0 u000
EECON1
Legend:
Note 1:
2:
3:
4:
5:
6:
u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
See Table 4-3 for Reset value for specific condition.
Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as
PORTA pins, they are disabled and read ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
 2010 Microchip Technology Inc.
DS41303G-page 61
PIC18F2XK20/4XK20
TABLE 4-4:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Applicable Devices
Power-on Reset,
Brown-out Reset
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
IPR2
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
PIR2
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu(1)
PIE2
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
PIC18F2XK20 PIC18F4XK20
-111 1111
-111 1111
-uuu uuuu
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu(1)
PIC18F2XK20 PIC18F4XK20
-000 0000
-000 0000
-uuu uuuu(1)
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
PIC18F2XK20 PIC18F4XK20
-000 0000
-000 0000
-uuu uuuu
OSCTUNE
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
TRISE
IPR1
PIR1
PIE1
PIC18F2XK20 PIC18F4XK20
---- -111
---- -111
---- -uuu
TRISD
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
TRISC
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
TRISB
PIC18F2XK20 PIC18F4XK20
1111 1111
(5)
1111 1111
(5)
uuuu uuuu
(5)
uuuu uuuu(5)
TRISA
PIC18F2XK20 PIC18F4XK20
1111 1111
LATE
PIC18F2XK20 PIC18F4XK20
---- -xxx
---- -uuu
---- -uuu
LATD
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
LATC
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
LATB
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
PIC18F2XK20 PIC18F4XK20
xxxx xxxx(5)
uuuu uuuu(5)
uuuu uuuu(5)
PIC18F2XK20 PIC18F4XK20
---- x000
---- u000
---- uuuu
PIC18F2XK20 PIC18F4XK20
---- x---
---- u---
---- u---
LATA(5)
PORTE
PORTD
1111 1111
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
PORTC
PIC18F2XK20 PIC18F4XK20
xxxx xxxx
uuuu uuuu
uuuu uuuu
PORTB
PIC18F2XK20 PIC18F4XK20
xxx0 0000
(5)
PORTA
PIC18F2XK20 PIC18F4XK20
ANSELH(6)
xx0x 0000
uuu0 0000
(5)
uu0u 0000
uuuu uuuu
(5)
uuuu uuuu(5)
PIC18F2XK20 PIC18F4XK20
---1 1111
---1 1111
---u uuuu
ANSEL
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
IOCB
PIC18F2XK20 PIC18F4XK20
0000 ----
0000 ----
uuuu ----
WPUB
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
CM1CON0
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
PIC18F2XK20 PIC18F4XK20
0000 0000
0000 0000
uuuu uuuu
CM2CON0
Legend:
Note 1:
2:
3:
4:
5:
6:
u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
See Table 4-3 for Reset value for specific condition.
Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as
PORTA pins, they are disabled and read ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
DS41303G-page 62
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Applicable Devices
Power-on Reset,
Brown-out Reset
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
CM2CON1
PIC18F2XK20 PIC18F4XK20
0000 ----
0000 ----
uuuu ----
SLRCON
PIC18F2XK20 PIC18F4XK20
---1 1111
---1 1111
---u uuuu
PIC18F2XK20 PIC18F4XK20
1111 1111
1111 1111
uuuu uuuu
Register
SSPMSK
Legend:
Note 1:
2:
3:
4:
5:
6:
u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
See Table 4-3 for Reset value for specific condition.
Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as
PORTA pins, they are disabled and read ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
 2010 Microchip Technology Inc.
DS41303G-page 63
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 64
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
5.0
MEMORY ORGANIZATION
5.1
Program Memory Organization
PIC18 microcontrollers implement a 21-bit program
counter, which is capable of addressing a 2-Mbyte
program memory space. Accessing a location between
the upper boundary of the physically implemented
memory and the 2-Mbyte address will return all ‘0’s (a
NOP instruction).
There are three types of memory in PIC18 Enhanced
microcontroller devices:
• Program Memory
• Data RAM
• Data EEPROM
As Harvard architecture devices, the data and program
memories use separate busses; this allows for concurrent access of the two memory spaces. The data
EEPROM, for practical purposes, can be regarded as
a peripheral device, since it is addressed and accessed
through a set of control registers.
This family of devices contain the following:
• PIC18F23K20, PIC18F43K20: 8 Kbytes of Flash
Memory, up to 4,096 single-word instructions
• PIC18F24K20, PIC18F44K20: 16 Kbytes of Flash
Memory, up to 8,192 single-word instructions
• PIC18F25K20, PIC18F45K20: 32 Kbytes of Flash
Memory, up to 16,384 single-word instructions
• PIC18F26K20, PIC18F46K20: 64 Kbytes of Flash
Memory, up to 37,768 single-word instructions
Additional detailed information on the operation of the
Flash program memory is provided in Section 6.0
“Flash Program Memory”. Data EEPROM is
discussed separately in Section 7.0 “Data EEPROM
Memory”.
PIC18 devices have two interrupt vectors. The Reset
vector address is at 0000h and the interrupt vector
addresses are at 0008h and 0018h.
The program memory map for PIC18F2XK20/4XK20
devices is shown in Figure 5-1. Memory block details
are shown in Figure 23-2.
FIGURE 5-1:
PROGRAM MEMORY MAP AND STACK FOR PIC18F2XK20/4XK20 DEVICES
PC<20:0>
21
CALL,RCALL,RETURN
RETFIE,RETLW
Stack Level 1



Stack Level 31
2000h
0000h
High Priority Interrupt Vector
0008h
Low Priority Interrupt Vector
0018h
On-Chip
Program Memory
3FFFh
4000h
PIC18F23K20/
43K20
On-Chip
Program Memory
User Memory Space
On-Chip
Program Memory
1FFFh
Reset Vector
On-Chip
Program Memory
PIC18F24K20/
44K20
7FFFh
8000h
PIC18F25K20/
45K20
Read ‘0’
Read ‘0’
Read ‘0’
FFFFh
10000h
PIC18F26K20/
46K20
Read ‘0’
 2010 Microchip Technology Inc.
1FFFFFh
200000h
DS41303G-page 65
PIC18F2XK20/4XK20
5.1.1
PROGRAM COUNTER
The Program Counter (PC) specifies the address of the
instruction to fetch for execution. The PC is 21 bits wide
and is contained in three separate 8-bit registers. The
low byte, known as the PCL register, is both readable
and writable. The high byte, or PCH register, contains
the PC<15:8> bits; it is not directly readable or writable.
Updates to the PCH register are performed through the
PCLATH register. The upper byte is called PCU. This
register contains the PC<20:16> bits; it is also not
directly readable or writable. Updates to the PCU
register are performed through the PCLATU register.
The contents of PCLATH and PCLATU are transferred
to the program counter by any operation that writes
PCL. Similarly, the upper two bytes of the program
counter are transferred to PCLATH and PCLATU by an
operation that reads PCL. This is useful for computed
offsets to the PC (see Section 5.1.4.1 “Computed
GOTO”).
The PC addresses bytes in the program memory. To
prevent the PC from becoming misaligned with word
instructions, the Least Significant bit of PCL is fixed to
a value of ‘0’. The PC increments by 2 to address
sequential instructions in the program memory.
The CALL, RCALL, GOTO and program branch
instructions write to the program counter directly. For
these instructions, the contents of PCLATH and
PCLATU are not transferred to the program counter.
5.1.2
RETURN ADDRESS STACK
The return address stack allows any combination of up
to 31 program calls and interrupts to occur. The PC is
pushed onto the stack when a CALL or RCALL
instruction is executed or an interrupt is Acknowledged.
The PC value is pulled off the stack on a RETURN,
RETLW or a RETFIE instruction. PCLATU and PCLATH
are not affected by any of the RETURN or CALL
instructions.
FIGURE 5-2:
The stack operates as a 31-word by 21-bit RAM and a
5-bit Stack Pointer, STKPTR. The stack space is not
part of either program or data space. The Stack Pointer
is readable and writable and the address on the top of
the stack is readable and writable through the Top-ofStack (TOS) Special File Registers. Data can also be
pushed to, or popped from the stack, using these
registers.
A CALL type instruction causes a push onto the stack;
the Stack Pointer is first incremented and the location
pointed to by the Stack Pointer is written with the
contents of the PC (already pointing to the instruction
following the CALL). A RETURN type instruction causes
a pop from the stack; the contents of the location
pointed to by the STKPTR are transferred to the PC
and then the Stack Pointer is decremented.
The Stack Pointer is initialized to ‘00000’ after all
Resets. There is no RAM associated with the location
corresponding to a Stack Pointer value of ‘00000’; this
is only a Reset value. Status bits indicate if the stack is
full or has overflowed or has underflowed.
5.1.2.1
Top-of-Stack Access
Only the top of the return address stack (TOS) is readable
and writable. A set of three registers, TOSU:TOSH:TOSL,
hold the contents of the stack location pointed to by the
STKPTR register (Figure 5-2). This allows users to
implement a software stack if necessary. After a CALL,
RCALL or interrupt, the software can read the pushed
value by reading the TOSU:TOSH:TOSL registers. These
values can be placed on a user defined software stack. At
return time, the software can return these values to
TOSU:TOSH:TOSL and do a return.
The user must disable the global interrupt enable bits
while accessing the stack to prevent inadvertent stack
corruption.
RETURN ADDRESS STACK AND ASSOCIATED REGISTERS
Return Address Stack <20:0>
11111
11110
11101
Top-of-Stack Registers
TOSU
00h
TOSH
1Ah
DS41303G-page 66
STKPTR<4:0>
00010
TOSL
34h
Top-of-Stack
Stack Pointer
001A34h
000D58h
00011
00010
00001
00000
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
5.1.2.2
Return Stack Pointer (STKPTR)
When the stack has been popped enough times to
unload the stack, the next pop will return a value of zero
to the PC and sets the STKUNF bit, while the Stack
Pointer remains at zero. The STKUNF bit will remain
set until cleared by software or until a POR occurs.
The STKPTR register (Register 5-1) contains the Stack
Pointer value, the STKFUL (stack full) Status bit and
the STKUNF (stack underflow) Status bits. The value of
the Stack Pointer can be 0 through 31. The Stack
Pointer increments before values are pushed onto the
stack and decrements after values are popped off the
stack. On Reset, the Stack Pointer value will be zero.
The user may read and write the Stack Pointer value.
This feature can be used by a Real-Time Operating
System (RTOS) for return stack maintenance.
Note:
After the PC is pushed onto the stack 31 times (without
popping any values off the stack), the STKFUL bit is
set. The STKFUL bit is cleared by software or by a
POR.
5.1.2.3
PUSH and POP Instructions
Since the Top-of-Stack is readable and writable, the
ability to push values onto the stack and pull values off
the stack without disturbing normal program execution
is a desirable feature. The PIC18 instruction set
includes two instructions, PUSH and POP, that permit
the TOS to be manipulated under software control.
TOSU, TOSH and TOSL can be modified to place data
or a return address on the stack.
The action that takes place when the stack becomes
full depends on the state of the STVREN (Stack Overflow Reset Enable) Configuration bit. (Refer to
Section 23.1 “Configuration Bits” for a description of
the device Configuration bits.) If STVREN is set
(default), the 31st push will push the (PC + 2) value
onto the stack, set the STKFUL bit and reset the
device. The STKFUL bit will remain set and the Stack
Pointer will be set to zero.
The PUSH instruction places the current PC value onto
the stack. This increments the Stack Pointer and loads
the current PC value onto the stack.
If STVREN is cleared, the STKFUL bit will be set on the
31st push and the Stack Pointer will increment to 31.
Any additional pushes will not overwrite the 31st push
and STKPTR will remain at 31.
REGISTER 5-1:
Returning a value of zero to the PC on an
underflow has the effect of vectoring the
program to the Reset vector, where the
stack conditions can be verified and
appropriate actions can be taken. This is
not the same as a Reset, as the contents
of the SFRs are not affected.
The POP instruction discards the current TOS by decrementing the Stack Pointer. The previous value pushed
onto the stack then becomes the TOS value.
STKPTR: STACK POINTER REGISTER
R/C-0
R/C-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
STKFUL(1)
STKUNF(1)
—
SP4
SP3
SP2
SP1
SP0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented
C = Clearable only bit
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
STKFUL: Stack Full Flag bit(1)
1 = Stack became full or overflowed
0 = Stack has not become full or overflowed
bit 6
STKUNF: Stack Underflow Flag bit(1)
1 = Stack underflow occurred
0 = Stack underflow did not occur
bit 5
Unimplemented: Read as ‘0’
bit 4-0
SP<4:0>: Stack Pointer Location bits
Note 1:
Bit 7 and bit 6 are cleared by user software or by a POR.
 2010 Microchip Technology Inc.
DS41303G-page 67
PIC18F2XK20/4XK20
5.1.2.4
Stack Full and Underflow Resets
Device Resets on stack overflow and stack underflow
conditions are enabled by setting the STVREN bit in
Configuration Register 4L. When STVREN is set, a full
or underflow will set the appropriate STKFUL or
STKUNF bit and then cause a device Reset. When
STVREN is cleared, a full or underflow condition will set
the appropriate STKFUL or STKUNF bit but not cause
a device Reset. The STKFUL or STKUNF bits are
cleared by the user software or a Power-on Reset.
5.1.3
FAST REGISTER STACK
A fast register stack is provided for the Status, WREG
and BSR registers, to provide a “fast return” option for
interrupts. The stack for each register is only one level
deep and is neither readable nor writable. It is loaded
with the current value of the corresponding register
when the processor vectors for an interrupt. All interrupt sources will push values into the stack registers.
The values in the registers are then loaded back into
their associated registers if the RETFIE, FAST
instruction is used to return from the interrupt.
5.1.4
LOOK-UP TABLES IN PROGRAM
MEMORY
There may be programming situations that require the
creation of data structures, or look-up tables, in
program memory. For PIC18 devices, look-up tables
can be implemented in two ways:
• Computed GOTO
• Table Reads
5.1.4.1
Computed GOTO
A computed GOTO is accomplished by adding an offset
to the program counter. An example is shown in
Example 5-2.
A look-up table can be formed with an ADDWF PCL
instruction and a group of RETLW nn instructions. The
W register is loaded with an offset into the table before
executing a call to that table. The first instruction of the
called routine is the ADDWF PCL instruction. The next
instruction executed will be one of the RETLW nn
instructions that returns the value ‘nn’ to the calling
function.
If both low and high priority interrupts are enabled, the
stack registers cannot be used reliably to return from
low priority interrupts. If a high priority interrupt occurs
while servicing a low priority interrupt, the stack register
values stored by the low priority interrupt will be
overwritten. In these cases, users must save the key
registers by software during a low priority interrupt.
The offset value (in WREG) specifies the number of
bytes that the program counter should advance and
should be multiples of 2 (LSb = 0).
If interrupt priority is not used, all interrupts may use the
fast register stack for returns from interrupt. If no
interrupts are used, the fast register stack can be used
to restore the Status, WREG and BSR registers at the
end of a subroutine call. To use the fast register stack
for a subroutine call, a CALL label, FAST instruction
must be executed to save the Status, WREG and BSR
registers to the fast register stack. A RETURN, FAST
instruction is then executed to restore these registers
from the fast register stack.
EXAMPLE 5-2:
Example 5-1 shows a source code example that uses
the fast register stack during a subroutine call and
return.
EXAMPLE 5-1:
CALL SUB1, FAST
FAST REGISTER STACK
CODE EXAMPLE
;STATUS, WREG, BSR
;SAVED IN FAST REGISTER
;STACK




RETURN, FAST
SUB1
DS41303G-page 68
;RESTORE VALUES SAVED
;IN FAST REGISTER STACK
In this method, only one data byte may be stored in
each instruction location and room on the return
address stack is required.
ORG
TABLE
5.1.4.2
MOVF
CALL
nn00h
ADDWF
RETLW
RETLW
RETLW
.
.
.
COMPUTED GOTO USING
AN OFFSET VALUE
OFFSET, W
TABLE
PCL
nnh
nnh
nnh
Table Reads and Table Writes
A better method of storing data in program memory
allows two bytes of data to be stored in each instruction
location.
Look-up table data may be stored two bytes per program word by using table reads and writes. The Table
Pointer (TBLPTR) register specifies the byte address
and the Table Latch (TABLAT) register contains the
data that is read from or written to program memory.
Data is transferred to or from program memory one
byte at a time.
Table read and table write operations are discussed
further in Section 6.1 “Table Reads and Table
Writes”.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
5.2
5.2.2
PIC18 Instruction Cycle
5.2.1
An “Instruction Cycle” consists of four Q cycles: Q1
through Q4. The instruction fetch and execute are
pipelined in such a manner that a fetch takes one
instruction cycle, while the decode and execute take
another instruction cycle. However, due to the
pipelining, each instruction effectively executes in one
cycle. If an instruction causes the program counter to
change (e.g., GOTO), then two cycles are required to
complete the instruction (Example 5-3).
CLOCKING SCHEME
The microcontroller clock input, whether from an
internal or external source, is internally divided by four
to generate four non-overlapping quadrature clocks
(Q1, Q2, Q3 and Q4). Internally, the program counter is
incremented on every Q1; the instruction is fetched
from the program memory and latched into the
instruction register during Q4. The instruction is
decoded and executed during the following Q1 through
Q4. The clocks and instruction execution flow are
shown in Figure 5-3.
FIGURE 5-3:
INSTRUCTION FLOW/PIPELINING
A fetch cycle begins with the Program Counter (PC)
incrementing in Q1.
In the execution cycle, the fetched instruction is latched
into the Instruction Register (IR) in cycle Q1. This
instruction is then decoded and executed during the
Q2, Q3 and Q4 cycles. Data memory is read during Q2
(operand read) and written during Q4 (destination
write).
CLOCK/INSTRUCTION CYCLE
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
OSC1
Q1
Q2
Internal
Phase
Clock
Q3
Q4
PC
PC
PC + 2
PC + 4
OSC2/CLKOUT
(RC mode)
Execute INST (PC – 2)
Fetch INST (PC)
EXAMPLE 5-3:
TCY0
TCY1
Fetch 1
Execute 1
2. MOVWF PORTB
4. BSF
Execute INST (PC + 2)
Fetch INST (PC + 4)
INSTRUCTION PIPELINE FLOW
1. MOVLW 55h
3. BRA
Execute INST (PC)
Fetch INST (PC + 2)
SUB_1
PORTA, BIT3 (Forced NOP)
5. Instruction @ address SUB_1
Fetch 2
TCY2
TCY3
TCY4
TCY5
Execute 2
Fetch 3
Execute 3
Fetch 4
Flush (NOP)
Fetch SUB_1 Execute SUB_1
All instructions are single cycle, except for any program branches. These take two cycles since the fetch instruction
is “flushed” from the pipeline while the new instruction is being fetched and then executed.
 2010 Microchip Technology Inc.
DS41303G-page 69
PIC18F2XK20/4XK20
5.2.3
INSTRUCTIONS IN PROGRAM
MEMORY
The program memory is addressed in bytes.
Instructions are stored as either two bytes or four bytes
in program memory. The Least Significant Byte of an
instruction word is always stored in a program memory
location with an even address (LSb = 0). To maintain
alignment with instruction boundaries, the PC
increments in steps of 2 and the LSb will always read
‘0’ (see Section 5.1.1 “Program Counter”).
Figure 5-4 shows an example of how instruction words
are stored in the program memory.
FIGURE 5-4:
The CALL and GOTO instructions have the absolute
program memory address embedded into the
instruction. Since instructions are always stored on word
boundaries, the data contained in the instruction is a
word address. The word address is written to PC<20:1>,
which accesses the desired byte address in program
memory. Instruction #2 in Figure 5-4 shows how the
instruction GOTO 0006h is encoded in the program
memory. Program branch instructions, which encode a
relative address offset, operate in the same manner. The
offset value stored in a branch instruction represents the
number of single-word instructions that the PC will be
offset by. Section 24.0 “Instruction Set Summary”
provides further details of the instruction set.
INSTRUCTIONS IN PROGRAM MEMORY
LSB = 1
LSB = 0
0Fh
EFh
F0h
C1h
F4h
55h
03h
00h
23h
56h
Program Memory
Byte Locations 
5.2.4
Instruction 1:
Instruction 2:
MOVLW
GOTO
055h
0006h
Instruction 3:
MOVFF
123h, 456h
TWO-WORD INSTRUCTIONS
The standard PIC18 instruction set has four two-word
instructions: CALL, MOVFF, GOTO and LSFR. In all
cases, the second word of the instruction always has
‘1111’ as its four Most Significant bits; the other 12 bits
are literal data, usually a data memory address.
The use of ‘1111’ in the 4 MSbs of an instruction
specifies a special form of NOP. If the instruction is
executed in proper sequence – immediately after the
first word – the data in the second word is accessed
EXAMPLE 5-4:
Word Address

000000h
000002h
000004h
000006h
000008h
00000Ah
00000Ch
00000Eh
000010h
000012h
000014h
and used by the instruction sequence. If the first word
is skipped for some reason and the second word is
executed by itself, a NOP is executed instead. This is
necessary for cases when the two-word instruction is
preceded by a conditional instruction that changes the
PC. Example 5-4 shows how this works.
Note:
See Section 5.6 “PIC18 Instruction
Execution and the Extended Instruction Set” for information on two-word
instructions in the extended instruction set.
TWO-WORD INSTRUCTIONS
CASE 1:
Object Code
0110 0110 0000
1100 0001 0010
1111 0100 0101
0010 0100 0000
0000
0011
0110
0000
Source Code
TSTFSZ
REG1
; is RAM location 0?
MOVFF
REG1, REG2 ; No, skip this word
; Execute this word as a NOP
ADDWF
REG3
; continue code
0000
0011
0110
0000
Source Code
TSTFSZ
REG1
; is RAM location 0?
MOVFF
REG1, REG2 ; Yes, execute this word
; 2nd word of instruction
ADDWF
REG3
; continue code
CASE 2:
Object Code
0110 0110 0000
1100 0001 0010
1111 0100 0101
0010 0100 0000
DS41303G-page 70
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
5.3
Note:
Data Memory Organization
The operation of some aspects of data
memory are changed when the PIC18
extended instruction set is enabled. See
Section 5.5 “Data Memory and the
Extended Instruction Set” for more
information.
The data memory in PIC18 devices is implemented as
static RAM. Each register in the data memory has a
12-bit address, allowing up to 4096 bytes of data
memory. The memory space is divided into as many as
16 banks that contain 256 bytes each. Figures 5-5
through 5-7 show the data memory organization for the
PIC18F2XK20/4XK20 devices.
The data memory contains Special Function Registers
(SFRs) and General Purpose Registers (GPRs). The
SFRs are used for control and status of the controller
and peripheral functions, while GPRs are used for data
storage and scratchpad operations in the user’s
application. Any read of an unimplemented location will
read as ‘0’s.
The instruction set and architecture allow operations
across all banks. The entire data memory may be
accessed by Direct, Indirect or Indexed Addressing
modes. Addressing modes are discussed later in this
subsection.
To ensure that commonly used registers (SFRs and
select GPRs) can be accessed in a single cycle, PIC18
devices implement an Access Bank. This is a 256-byte
memory space that provides fast access to SFRs and
the lower portion of GPR Bank 0 without using the Bank
Select Register (BSR). Section 5.3.2 “Access Bank”
provides a detailed description of the Access RAM.
5.3.1
BANK SELECT REGISTER (BSR)
Large areas of data memory require an efficient
addressing scheme to make rapid access to any
address possible. Ideally, this means that an entire
address does not need to be provided for each read or
write operation. For PIC18 devices, this is accomplished with a RAM banking scheme. This divides the
memory space into 16 contiguous banks of 256 bytes.
Depending on the instruction, each location can be
addressed directly by its full 12-bit address, or an 8-bit
low-order address and a 4-bit Bank Pointer.
Most instructions in the PIC18 instruction set make use
of the Bank Pointer, known as the Bank Select Register
(BSR). This SFR holds the 4 Most Significant bits of a
location’s address; the instruction itself includes the
8 Least Significant bits. Only the four lower bits of the
BSR are implemented (BSR<3:0>). The upper four bits
are unused; they will always read ‘0’ and cannot be
written to. The BSR can be loaded directly by using the
MOVLB instruction.
The value of the BSR indicates the bank in data
memory; the 8 bits in the instruction show the location
in the bank and can be thought of as an offset from the
bank’s lower boundary. The relationship between the
BSR’s value and the bank division in data memory is
shown in Figures 5-5 through 5-7.
Since up to 16 registers may share the same low-order
address, the user must always be careful to ensure that
the proper bank is selected before performing a data
read or write. For example, writing what should be
program data to an 8-bit address of F9h while the BSR
is 0Fh will end up resetting the program counter.
While any bank can be selected, only those banks that
are actually implemented can be read or written to.
Writes to unimplemented banks are ignored, while
reads from unimplemented banks will return ‘0’s. Even
so, the STATUS register will still be affected as if the
operation was successful. The data memory maps in
Figures 5-5 through 5-7 indicate which banks are
implemented.
In the core PIC18 instruction set, only the MOVFF
instruction fully specifies the 12-bit address of the
source and target registers. This instruction ignores the
BSR completely when it executes. All other instructions
include only the low-order address as an operand and
must use either the BSR or the Access Bank to locate
their target registers.
 2010 Microchip Technology Inc.
DS41303G-page 71
PIC18F2XK20/4XK20
FIGURE 5-5:
DATA MEMORY MAP FOR PIC18F23K20/43K20 DEVICES
BSR<3:0>
= 0000
00h
Access RAM
FFh
00h
GPR
Bank 0
= 0001
= 0011
= 0100
= 0101
= 0110
= 0111
= 1000
= 1001
= 1010
= 1011
= 1100
= 1101
= 1110
= 1111
DS41303G-page 72
000h
05Fh
060h
0FFh
100h
GPR
Bank 1
= 0010
When ‘a’ = 0:
Data Memory Map
FFh
00h
1FFh
200h
FFh
00h
2FFh
300h
FFh
00h
3FFh
400h
FFh
00h
4FFh
500h
FFh
00h
5FFh
600h
FFh
00h
6FFh
700h
The BSR is ignored and the
Access Bank is used.
The first 96 bytes are
general purpose RAM
(from Bank 0).
The second 160 bytes are
Special Function Registers
(from Bank 15).
Bank 2
Bank 3
Bank 4
Bank 5
When ‘a’ = 1:
The BSR specifies the Bank
used by the instruction.
Bank 6
Bank 7
Bank 8
Bank 9
7FFh
800h
FFh
00h
FFh
00h
Unused
Read 00h
9FFh
A00h
FFh
00h
AFFh
B00h
FFh
00h
BFFh
C00h
FFh
Bank 13 00h
CFFh
D00h
FFh
00h
DFFh
E00h
Bank 11
Bank 12
Access RAM Low
00h
5Fh
Access RAM High 60h
(SFRs)
FFh
8FFh
900h
FFh
00h
Bank 10
Access Bank
Bank 14
FFh
00h
Unused
FFh
SFR
Bank 15
EFFh
F00h
F5Fh
F60h
FFFh
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 5-6:
DATA MEMORY MAP FOR PIC18F24K20/44K20 DEVICES
BSR<3:0>
= 0000
00h
Access RAM
FFh
00h
GPR
Bank 0
= 0001
= 0011
= 0100
= 0101
= 0110
= 0111
= 1000
= 1001
= 1010
= 1011
= 1100
= 1101
= 1110
= 1111
1FFh
200h
FFh
00h
Bank 2
Bank 3
Bank 4
Bank 5
000h
05Fh
060h
0FFh
100h
GPR
Bank 1
= 0010
When ‘a’ = 0:
Data Memory Map
The BSR is ignored and the
Access Bank is used.
The first 96 bytes are
general purpose RAM
(from Bank 0).
The second 160 bytes are
Special Function Registers
(from Bank 15).
GPR
FFh
00h
2FFh
300h
FFh
00h
3FFh
400h
FFh
00h
4FFh
500h
FFh
00h
5FFh
600h
FFh
00h
6FFh
700h
When ‘a’ = 1:
The BSR specifies the Bank
used by the instruction.
Bank 6
Bank 7
Bank 8
Bank 9
7FFh
800h
FFh
00h
FFh
00h
Unused
Read 00h
9FFh
A00h
FFh
00h
AFFh
B00h
FFh
00h
BFFh
C00h
FFh
Bank 13 00h
CFFh
D00h
FFh
00h
DFFh
E00h
Bank 11
Bank 12
Access RAM Low
00h
5Fh
Access RAM High 60h
(SFRs)
FFh
8FFh
900h
FFh
00h
Bank 10
Access Bank
Bank 14
FFh
00h
Unused
FFh
SFR
Bank 15
 2010 Microchip Technology Inc.
EFFh
F00h
F5Fh
F60h
FFFh
DS41303G-page 73
PIC18F2XK20/4XK20
FIGURE 5-7:
DATA MEMORY MAP FOR PIC18F25K20/45K20 DEVICES
BSR<3:0>
= 0000
00h
Access RAM
FFh
00h
GPR
Bank 0
= 0001
= 0011
= 0100
= 0101
= 0110
= 0111
= 1000
= 1001
= 1010
= 1011
= 1100
= 1101
= 1110
= 1111
DS41303G-page 74
1FFh
200h
FFh
00h
Bank 2
Bank 3
Bank 4
Bank 5
000h
05Fh
060h
0FFh
100h
GPR
Bank 1
= 0010
When ‘a’ = 0:
Data Memory Map
The BSR is ignored and the
Access Bank is used.
The first 96 bytes are
general purpose RAM
(from Bank 0).
The second 160 bytes are
Special Function Registers
(from Bank 15).
GPR
FFh
00h
2FFh
300h
GPR
3FFh
400h
FFh
00h
When ‘a’ = 1:
The BSR specifies the Bank
used by the instruction.
GPR
4FFh
500h
FFh
00h
GPR
FFh
00h
5FFh
600h
FFh
00h
6FFh
700h
Bank 6
Bank 7
Bank 8
Bank 9
Bank 10
FFh
00h
7FFh
800h
FFh
00h
8FFh
900h
FFh
00h
Unused
Read 00h
AFFh
B00h
FFh
00h
BFFh
C00h
FFh
Bank 13 00h
CFFh
D00h
FFh
00h
DFFh
E00h
Bank 12
Access RAM Low
00h
5Fh
Access RAM High 60h
(SFRs)
FFh
9FFh
A00h
FFh
00h
Bank 11
Access Bank
Bank 14
FFh
00h
Unused
FFh
SFR
Bank 15
EFFh
F00h
F5Fh
F60h
FFFh
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 5-8:
DATA MEMORY MAP FOR PIC18F26K20/46K20 DEVICES
BSR<3:0>
= 0000
00h
Access RAM
FFh
00h
GPR
Bank 0
= 0001
= 0011
= 0100
= 0101
= 0110
= 0111
= 1000
= 1001
= 1010
= 1011
= 1100
= 1101
= 1110
= 1111
1FFh
200h
FFh
00h
Bank 2
Bank 3
Bank 4
Bank 5
2FFh
300h
GPR
3FFh
400h
FFh
00h
Bank 12
The BSR specifies the Bank
used by the instruction.
5FFh
600h
GPR
6FFh
700h
GPR
7FFh
800h
FFh
00h
GPR
Access Bank
Access RAM Low
00h
5Fh
Access RAM High 60h
(SFRs)
FFh
8FFh
900h
FFh
00h
GPR
9FFh
A00h
FFh
00h
GPR
AFFh
B00h
FFh
00h
GPR
FFh
00h
FFh
Bank 13 00h
BFFh
C00h
GPR
CFFh
D00h
GPR
DFFh
E00h
FFh
00h
GPR
Bank 14
FFh
00h
GPR
FFh
SFR
Bank 15
 2010 Microchip Technology Inc.
When ‘a’ = 1:
GPR
Bank 7
Bank 11
The second 160 bytes are
Special Function Registers
(from Bank 15).
4FFh
500h
FFh
00h
Bank 10
The first 96 bytes are
general purpose RAM
(from Bank 0).
GPR
FFh
00h
Bank 6
Bank 9
The BSR is ignored and the
Access Bank is used.
GPR
FFh
00h
FFh
00h
Bank 8
000h
05Fh
060h
0FFh
100h
GPR
Bank 1
= 0010
When ‘a’ = 0:
Data Memory Map
EFFh
F00h
F5Fh
F60h
FFFh
DS41303G-page 75
PIC18F2XK20/4XK20
FIGURE 5-9:
USE OF THE BANK SELECT REGISTER (DIRECT ADDRESSING)
0
Data Memory
BSR(1)
7
0
0
0
0
0
0
1
1
000h
00h
Bank 0
100h
Bank 1
Bank Select(2)
FFh
00h
From Opcode(2)
7
1
1
1
1
1
1
0
1
1
FFh
00h
200h
Bank 2
300h
FFh
00h
Bank 3
through
Bank 13
FFh
00h
E00h
Bank 14
F00h
Bank 15
FFFh
Note 1:
2:
FFh
00h
FFh
The Access RAM bit of the instruction can be used to force an override of the selected bank (BSR<3:0>) to
the registers of the Access Bank.
The MOVFF instruction embeds the entire 12-bit address in the instruction.
DS41303G-page 76
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
5.3.2
ACCESS BANK
While the use of the BSR with an embedded 8-bit
address allows users to address the entire range of
data memory, it also means that the user must always
ensure that the correct bank is selected. Otherwise,
data may be read from or written to the wrong location.
This can be disastrous if a GPR is the intended target
of an operation, but an SFR is written to instead.
Verifying and/or changing the BSR for each read or
write to data memory can become very inefficient.
To streamline access for the most commonly used data
memory locations, the data memory is configured with
an Access Bank, which allows users to access a
mapped block of memory without specifying a BSR.
The Access Bank consists of the first 96 bytes of memory (00h-5Fh) in Bank 0 and the last 160 bytes of memory (60h-FFh) in Block 15. The lower half is known as
the “Access RAM” and is composed of GPRs. This
upper half is also where the device’s SFRs are
mapped. These two areas are mapped contiguously in
the Access Bank and can be addressed in a linear
fashion by an 8-bit address (Figures 5-5 through 5-7).
The Access Bank is used by core PIC18 instructions
that include the Access RAM bit (the ‘a’ parameter in
the instruction). When ‘a’ is equal to ‘1’, the instruction
uses the BSR and the 8-bit address included in the
opcode for the data memory address. When ‘a’ is ‘0’,
however, the instruction is forced to use the Access
Bank address map; the current value of the BSR is
ignored entirely.
5.3.3
GENERAL PURPOSE REGISTER
FILE
PIC18 devices may have banked memory in the GPR
area. This is data RAM, which is available for use by all
instructions. GPRs start at the bottom of Bank 0
(address 000h) and grow upwards towards the bottom of
the SFR area. GPRs are not initialized by a Power-on
Reset and are unchanged on all other Resets.
5.3.4
SPECIAL FUNCTION REGISTERS
The Special Function Registers (SFRs) are registers
used by the CPU and peripheral modules for controlling
the desired operation of the device. These registers are
implemented as static RAM. SFRs start at the top of
data memory (FFFh) and extend downward to occupy
the top portion of Bank 15 (F60h to FFFh). A list of
these registers is given in Table 5-1 and Table 5-2.
The SFRs can be classified into two sets: those
associated with the “core” device functionality (ALU,
Resets and interrupts) and those related to the
peripheral functions. The Reset and interrupt registers
are described in their respective chapters, while the
ALU’s STATUS register is described later in this
section. Registers related to the operation of a
peripheral feature are described in the chapter for that
peripheral.
The SFRs are typically distributed among the
peripherals whose functions they control. Unused SFR
locations are unimplemented and read as ‘0’s.
Using this “forced” addressing allows the instruction to
operate on a data address in a single cycle, without
updating the BSR first. For 8-bit addresses of 60h and
above, this means that users can evaluate and operate
on SFRs more efficiently. The Access RAM below 60h
is a good place for data values that the user might need
to access rapidly, such as immediate computational
results or common program variables. Access RAM
also allows for faster and more code efficient context
saving and switching of variables.
The mapping of the Access Bank is slightly different
when the extended instruction set is enabled (XINST
Configuration bit = 1). This is discussed in more detail
in Section 5.5.3 “Mapping the Access Bank in
Indexed Literal Offset Mode”.
 2010 Microchip Technology Inc.
DS41303G-page 77
PIC18F2XK20/4XK20
TABLE 5-1:
SPECIAL FUNCTION REGISTER MAP FOR PIC18F2XK20/4XK20 DEVICES
Address
Name
Address
Name
Address
Name
Address
Name
FFFh
TOSU
FD7h
TMR0H
FAFh
SPBRG
F87h
—(2)
FFEh
TOSH
FD6h
TMR0L
FAEh
RCREG
F86h
—(2)
FFDh
TOSL
FD5h
T0CON
FADh
TXREG
F85h
—(2)
FFCh
STKPTR
FD4h
—(2)
FACh
TXSTA
F84h
PORTE
FFBh
PCLATU
FD3h
OSCCON
FABh
RCSTA
F83h
PORTD(3)
FFAh
PCLATH
FD2h
HLVDCON
FAAh
EEADRH(4)
F82h
PORTC
FF9h
PCL
FD1h
WDTCON
FA9h
EEADR
F81h
PORTB
FF8h
TBLPTRU
FD0h
RCON
FA8h
EEDATA
F80h
PORTA
FF7h
TBLPTRH
FCFh
TMR1H
FA7h
EECON2(1)
F7Fh
ANSELH
FF6h
TBLPTRL
FCEh
TMR1L
FA6h
EECON1
F7Eh
ANSEL
FF5h
TABLAT
FCDh
T1CON
FA5h
—(2)
F7Dh
IOCB
FF4h
PRODH
FCCh
TMR2
FA4h
—(2)
F7Ch
WPUB
FF3h
PRODL
FCBh
PR2
FA3h
—(2)
F7Bh
CM1CON0
FF2h
INTCON
FCAh
T2CON
FA2h
IPR2
F7Ah
CM2CON0
FF1h
INTCON2
FC9h
SSPBUF
FA1h
PIR2
F79h
CM2CON1
FF0h
INTCON3
FC8h
SSPADD
FA0h
PIE2
F78h
SLRCON
FEFh
INDF0(1)
FC7h
SSPSTAT
F9Fh
IPR1
F77h
SSPMSK
FEEh POSTINC0(1)
FC6h
SSPCON1
F9Eh
PIR1
F76h
—(2)
FEDh
POSTDEC0(1)
FC5h
SSPCON2
F9Dh
PIE1
F75h
—(2)
FECh
PREINC0(1)
FC4h
ADRESH
F9Ch
—(2)
F74h
—(2)
FEBh
PLUSW0(1)
FC3h
ADRESL
F9Bh
OSCTUNE
F73h
—(2)
FEAh
FSR0H
FC2h
ADCON0
F9Ah
—(2)
F72h
—(2)
F71h
—(2)
FE9h
FSR0L
FC1h
ADCON1
F99h
—(2)
FE8h
WREG
FC0h
ADCON2
F98h
—(2)
F70h
—(2)
FE7h
INDF1(1)
F6Fh
—(2)
FE6h POSTINC1(1)
FBFh
CCPR1H
F97h
—(2)
FBEh
CCPR1L
F96h
TRISE(3)
F6Eh
—(2)
F6Dh
—(2)
FE5h
POSTDEC1(1)
FBDh
CCP1CON
F95h
TRISD(3)
FE4h
PREINC1(1)
FBCh
CCPR2H
F94h
TRISC
F6Ch
—(2)
FE3h
PLUSW1(1)
FBBh
CCPR2L
F93h
TRISB
F6Bh
—(2)
FE2h
FSR1H
FBAh
CCP2CON
F92h
TRISA
F6Ah
—(2)
(2)
FE1h
FSR1L
FB9h
PSTRCON
F91h
—
F69h
—(2)
FE0h
BSR
FB8h
BAUDCON
F90h
—(2)
F68h
—(2)
FDFh
INDF2(1)
F67h
—(2)
FDEh POSTINC2(1)
(1)
FDDh POSTDEC2
FB7h
PWM1CON
F8Fh
—(2)
FB6h
ECCP1AS
F8Eh
—(2)
FB5h
CVRCON
F8Dh
LATE
F66h
—(2)
(3)
F65h
—(2)
FDCh
PREINC2(1)
FB4h
CVRCON2
F8Ch
LATD(3)
F64h
—(2)
FDBh
PLUSW2(1)
FB3h
TMR3H
F8Bh
LATC
F63h
—(2)
FDAh
FSR2H
FB2h
TMR3L
F8Ah
LATB
F62h
—(2)
FD9h
FSR2L
FB1h
T3CON
F89h
LATA
F61h
—(2)
FD8h
STATUS
FB0h
SPBRGH
F88h
—(2)
F60h
—(2)
Note 1:
2:
3:
4:
This is not a physical register.
Unimplemented registers are read as ‘0’.
This register is not available on PIC18F2XK20 devices.
This register is only implemented in the PIC18F46K20 and PIC18F26K20 devices.
DS41303G-page 78
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 5-2:
File Name
TOSU
REGISTER FILE SUMMARY (PIC18F2XK20/4XK20)
Bit 7
Bit 6
Bit 5
—
—
—
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Details
on page:
---0 0000
59, 66
TOSH
Top-of-Stack, High Byte (TOS<15:8>)
0000 0000
59, 66
TOSL
Top-of-Stack, Low Byte (TOS<7:0>)
0000 0000
59, 66
00-0 0000
59, 67
STKPTR
PCLATU
STKFUL
STKUNF
—
—
—
—
Top-of-Stack Upper Byte (TOS<20:16>)
Value on
POR, BOR
SP4
SP3
SP2
SP1
SP0
---0 0000
59, 66
PCLATH
Holding Register for PC<15:8>
0000 0000
59, 66
PCL
PC, Low Byte (PC<7:0>)
0000 0000
59, 66
--00 0000
59, 92
TBLPTRU
—
—
bit 21
Holding Register for PC<20:16>
Program Memory Table Pointer Upper Byte (TBLPTR<20:16>)
TBLPTRH
Program Memory Table Pointer, High Byte (TBLPTR<15:8>)
0000 0000
59, 92
TBLPTRL
Program Memory Table Pointer, Low Byte (TBLPTR<7:0>)
0000 0000
59, 92
TABLAT
Program Memory Table Latch
0000 0000
59, 92
PRODH
Product Register, High Byte
xxxx xxxx
59, 105
PRODL
Product Register, Low Byte
xxxx xxxx
59, 105
INTCON
GIE/GIEH
PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
0000 000x
59, 109
INTCON2
RBPU
INTEDG0
INTEDG1
INTEDG2
—
TMR0IP
—
RBIP
1111 -1-1
59, 110
INTCON3
INT2IP
INT1IP
—
INT2IE
INT1IE
—
INT2IF
INT1IF
11-0 0-00
59, 111
INDF0
Uses contents of FSR0 to address data memory – value of FSR0 not changed (not a physical register)
N/A
59, 84
POSTINC0
Uses contents of FSR0 to address data memory – value of FSR0 post-incremented (not a physical register)
N/A
59, 84
POSTDEC0
Uses contents of FSR0 to address data memory – value of FSR0 post-decremented (not a physical register)
N/A
59, 84
PREINC0
Uses contents of FSR0 to address data memory – value of FSR0 pre-incremented (not a physical register)
N/A
59, 84
PLUSW0
Uses contents of FSR0 to address data memory – value of FSR0 offset by W (not a physical register) –
N/A
59, 84
---- 0000
59, 84
59, 84
FSR0H
—
—
—
—
Indirect Data Memory Address Pointer 0, High Byte
FSR0L
Indirect Data Memory Address Pointer 0, Low Byte
xxxx xxxx
WREG
Working Register
xxxx xxxx
59
INDF1
Uses contents of FSR1 to address data memory – value of FSR1 not changed (not a physical register)
N/A
59, 84
POSTINC1
Uses contents of FSR1 to address data memory – value of FSR1 post-incremented (not a physical register)
N/A
59, 84
POSTDEC1
Uses contents of FSR1 to address data memory – value of FSR1 post-decremented (not a physical register)
N/A
59, 84
PREINC1
Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register)
N/A
59, 84
PLUSW1
Uses contents of FSR1 to address data memory – value of FSR1 offset by W (not a physical register) – value of
N/A
59, 84
---- 0000
60, 84
FSR1H
—
FSR1L
—
—
—
Indirect Data Memory Address Pointer 1, High Byte
Indirect Data Memory Address Pointer 1, Low Byte
BSR
—
—
—
—
Bank Select Register
xxxx xxxx
60, 84
---- 0000
60, 71
INDF2
Uses contents of FSR2 to address data memory – value of FSR2 not changed (not a physical register)
N/A
60, 84
POSTINC2
Uses contents of FSR2 to address data memory – value of FSR2 post-incremented (not a physical register)
N/A
60, 84
POSTDEC2
Uses contents of FSR2 to address data memory – value of FSR2 post-decremented (not a physical register)
N/A
60, 84
PREINC2
Uses contents of FSR2 to address data memory – value of FSR2 pre-incremented (not a physical register)
N/A
60, 84
PLUSW2
Uses contents of FSR2 to address data memory – value of FSR2 offset by W (not a physical register) – value of
N/A
60, 84
---- 0000
60, 84
FSR2H
—
FSR2L
—
—
—
Indirect Data Memory Address Pointer 2, High Byte
Indirect Data Memory Address Pointer 2, Low Byte
STATUS
Legend:
Note 1:
2:
3:
4:
5:
6:
7:
—
—
—
N
OV
Z
DC
C
xxxx xxxx
60, 84
---x xxxx
60, 82
x = unknown, u = unchanged, — = unimplemented, q = value depends on condition
The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise it is disabled and reads as ‘0’. See
Section 4.4 “Brown-out Reset (BOR)”.
These registers and/or bits are not implemented on 28-pin devices and are read as ‘0’. Reset values are shown for 40/44-pin devices;
individual unimplemented bits should be interpreted as ‘-’.
The PLLEN bit is only available in specific oscillator configuration; otherwise it is disabled and reads as ‘0’. See Section 2.6.2 “PLL in
HFINTOSC Modes”.
The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0). Otherwise, RE3 reads as ‘0’. This bit is
read-only.
RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes.
When disabled, these bits read as ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
This register is only implemented in the PIC18F46K20 and PIC18F26K20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 79
PIC18F2XK20/4XK20
TABLE 5-2:
File Name
REGISTER FILE SUMMARY (PIC18F2XK20/4XK20) (CONTINUED)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Details
on page:
TMR0H
Timer0 Register, High Byte
0000 0000
60, 157
TMR0L
Timer0 Register, Low Byte
xxxx xxxx
60, 157
60, 155
T0CON
TMR0ON
T08BIT
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
1111 1111
OSCCON
IDLEN
IRCF2
IRCF1
IRCF0
OSTS
IOFS
SCS1
SCS0
0011 qq00
29, 60
HLVDCON
VDIRMAG
—
IRVST
HLVDEN
HLVDL3
HLVDL2
HLVDL1
HLVDL0
0-00 0101
60, 293
—
—
—
—
—
—
—
SWDTEN
--- ---0
60, 309
IPEN
SBOREN(1)
—
RI
TO
PD
POR
BOR
0q-1 11q0
51, 58,
118
WDTCON
RCON
TMR1H
Timer1 Register, High Byte
xxxx xxxx
60, 165
TMR1L
Timer1 Register, Low Bytes
xxxx xxxx
60, 165
T1CON
RD16
T1RUN
T1CKPS1
T1CKPS0
T1OSCEN
T1SYNC
0000 0000
60, 159
TMR2
Timer2 Register
0000 0000
60, 168
PR2
Timer2 Period Register
1111 1111
60, 168
-000 0000
60, 167
xxxx xxxx
60, 201,
202
T2CON
—
T2OUTPS3
T2OUTPS2
T2OUTPS1
T2OUTPS0
TMR2ON
TMR1CS
TMR1ON
T2CKPS1
T2CKPS0
SSPBUF
SSP Receive Buffer/Transmit Register
SSPADD
SSP Address Register in I2C™ Slave Mode. SSP Baud Rate Reload Register in I2C Master Mode.
0000 0000
60, 202
SSPSTAT
SMP
CKE
D/A
P
S
R/W
UA
BF
0000 0000
60, 194,
204
SSPCON1
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
0000 0000
60, 195,
205
GCEN
ACKSTAT
ACKDT
ACKEN
RCEN
PEN
RSEN
SEN
SSPCON2
0000 0000
60, 206
ADRESH
A/D Result Register, High Byte
xxxx xxxx
61, 277
ADRESL
A/D Result Register, Low Byte
xxxx xxxx
61, 277
ADCON0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
--00 0000
61, 271
ADCON1
—
—
VCFG1
VCFG0
—
—
—
—
--00 ----
59, 272
ADFM
—
ACQT2
ACQT1
ACQT0
ADCS2
ADCS1
ADCS0
ADCON2
0-00 0000
61, 273
CCPR1H
Capture/Compare/PWM Register 1, High Byte
xxxx xxxx
61, 144
CCPR1L
Capture/Compare/PWM Register 1, Low Byte
xxxx xxxx
61, 144
0000 0000
61, 173
61, 144
CCP1CON
P1M1
P1M0
DC1B1
DC1B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0
CCPR2H
Capture/Compare/PWM Register 2, High Byte
xxxx xxxx
CCPR2L
Capture/Compare/PWM Register 2, Low Byte
xxxx xxxx
61, 144
CCP2M0
--00 0000
61, 143
CCP2CON
—
—
DC2B1
DC2B0
CCP2M3
CCP2M2
CCP2M1
PSTRCON
—
—
—
STRSYNC
STRD
STRC
STRB
STRA
---0 0001
61, 187
BAUDCON
ABDOVF
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
0100 0-00
61, 248
PWM1CON
PRSEN
PDC6
PDC5
PDC4
PDC3
PDC2
PDC1
PDC0
0000 0000
61, 186
ECCP1AS
ECCPASE
ECCPAS2
ECCPAS1
ECCPAS0
PSSAC1
PSSAC0
PSSBD1
PSSBD0
0000 0000
61, 183
CVRCON
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
0000 0000
61, 291
CVRCON2
FVREN
FVRST
—
—
—
—
—
—
00-- ----
61, 292
TMR3H
Timer3 Register, High Byte
xxxx xxxx
61, 172
TMR3L
Timer3 Register, Low Byte
xxxx xxxx
61, 172
0000 0000
61, 169
T3CON
RD16
Legend:
Note 1:
2:
3:
4:
5:
6:
7:
T3CCP2
T3CKPS1
T3CKPS0
T3CCP1
T3SYNC
TMR3CS
TMR3ON
x = unknown, u = unchanged, — = unimplemented, q = value depends on condition
The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise it is disabled and reads as ‘0’. See
Section 4.4 “Brown-out Reset (BOR)”.
These registers and/or bits are not implemented on 28-pin devices and are read as ‘0’. Reset values are shown for 40/44-pin devices;
individual unimplemented bits should be interpreted as ‘-’.
The PLLEN bit is only available in specific oscillator configuration; otherwise it is disabled and reads as ‘0’. See Section 2.6.2 “PLL in
HFINTOSC Modes”.
The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0). Otherwise, RE3 reads as ‘0’. This bit is
read-only.
RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes.
When disabled, these bits read as ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
This register is only implemented in the PIC18F46K20 and PIC18F26K20 devices.
DS41303G-page 80
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 5-2:
File Name
REGISTER FILE SUMMARY (PIC18F2XK20/4XK20) (CONTINUED)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Details
on page:
SPBRGH
EUSART Baud Rate Generator Register, High Byte
0000 0000
61, 241
SPBRG
EUSART Baud Rate Generator Register, Low Byte
0000 0000
61, 241
RCREG
EUSART Receive Register
0000 0000
61, 238
TXREG
EUSART Transmit Register
0000 0000
61, 237
TXSTA
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
0000 0010
61, 246
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
61, 247
EEADR
EEADR7
EEADR6
EEADR5
EEADR4
EEADR3
EEADR2
EEADR1
EEADR0
0000 0000 61, 90, 99
—
—
—
—
—
—
EEADR9
EEADR8
---- --00 61, 90, 99
EEADRH(7)
EEDATA
EEPROM Data Register
EECON2
EEPROM Control Register 2 (not a physical register)
0000 0000 61, 90, 99
0000 0000 61, 90, 99
EECON1
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
1111 1111
62, 117
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
0000 0000
62, 113
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
0000 0000
62, 115
IPR1
PSPIP(2)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
1111 1111
62, 116
PIR1
PSPIF(2)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
62, 112
PIE1
PSPIE(2)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
62, 114
OSCTUNE
INTSRC
PLLEN(3)
TUN5
TUN4
TUN3
TUN2
TUN1
TUN0
0q00 0000
33, 62
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
0000 -111
62, 134
TRISE(2)
xx-0 x000 61, 91, 99
TRISD(2)
PORTD Data Direction Control Register
1111 1111
62, 130
TRISC
PORTC Data Direction Control Register
1111 1111
62, 127
TRISB
PORTB Data Direction Control Register
1111 1111
62, 124
1111 1111
62, 121
---- -xxx
62, 133
TRISA
TRISA7(5)
TRISA6(5)
LATE(2)
—
—
Data Direction Control Register for PORTA
—
—
—
PORTE Data Latch Register
(Read and Write to Data Latch)
LATD(2)
PORTD Data Latch Register (Read and Write to Data Latch)
xxxx xxxx
62, 130
LATC
PORTC Data Latch Register (Read and Write to Data Latch)
xxxx xxxx
62, 127
LATB
PORTB Data Latch Register (Read and Write to Data Latch)
xxxx xxxx
62, 124
xxxx xxxx
62, 121
LATA7(5)
LATA6(5)
—
—
—
—
RE3(4)
RE2(2)
RE1(2)
RE0(2)
---- x000
62, 133
PORTD(2)
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
xxxx xxxx
62, 130
PORTC
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
xxxx xxxx
62, 127
PORTB
RB7
RB6
RB5
RB4
RB3
RB2
RB1
RB0
xxx0 0000
62, 124
PORTA
RA7(5)
RA6(5)
RA5
RA4
RA3
RA2
RA1
RA0
xx0x 0000
62, 121
—
—
—
ANS12
ANS11
ANS10
ANS9
ANS8
---1 1111
62, 137
ANSEL
ANS7(2)
ANS6(2)
ANS5(2)
ANS4
ANS3
ANS2
ANS1
ANS0
1111 1111
62, 136
IOCB
IOCB7
IOCB6
IOCB5
IOCB4
—
—
—
—
0000 ----
62, 124
WPUB
WPUB7
WPUB6
WPUB5
WPUB4
WPUB3
WPUB2
WPUB1
WPUB0
1111 1111
62, 124
CM1CON0
C1ON
C1OUT
C1OE
C1POL
C1SP
C1R
C1CH1
C1CH0
0000 0000
62, 284
CM2CON0
C2ON
C2OUT
C2OE
C2POL
C2SP
C2R
C2CH1
C2CH0
0000 0000
62, 285
CM2CON1
MC1OUT
MC2OUT
C1RSEL
C2RSEL
—
—
—
—
0000 ----
63, 287
SLRCON
—
—
—
SLRE(2)
SLRD(2)
SLRC
SLRB
SLRA
---1 1111
63, 138
SSPMSK
MSK7
MSK6
MSK5
MSK4
MSK3
MSK2
MSK1
MSK0
1111 1111
63, 213
LATA
PORTE
ANSELH(6)
Legend:
Note 1:
2:
3:
4:
5:
6:
7:
PORTA Data Latch Register (Read and Write to Data Latch)
x = unknown, u = unchanged, — = unimplemented, q = value depends on condition
The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise it is disabled and reads as ‘0’. See
Section 4.4 “Brown-out Reset (BOR)”.
These registers and/or bits are not implemented on 28-pin devices and are read as ‘0’. Reset values are shown for 40/44-pin devices;
individual unimplemented bits should be interpreted as ‘-’.
The PLLEN bit is only available in specific oscillator configuration; otherwise it is disabled and reads as ‘0’. See Section 2.6.2 “PLL in
HFINTOSC Modes”.
The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0). Otherwise, RE3 reads as ‘0’. This bit is
read-only.
RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes.
When disabled, these bits read as ‘0’.
All bits of the ANSELH register initialize to ‘0’ if the PBADEN bit of CONFIG3H is ‘0’.
This register is only implemented in the PIC18F46K20 and PIC18F26K20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 81
PIC18F2XK20/4XK20
5.3.5
STATUS REGISTER
The STATUS register, shown in Register 5-2, contains
the arithmetic status of the ALU. As with any other SFR,
it can be the operand for any instruction.
If the STATUS register is the destination for an instruction that affects the Z, DC, C, OV or N bits, the results
of the instruction are not written; instead, the STATUS
register is updated according to the instruction performed. Therefore, the result of an instruction with the
STATUS register as its destination may be different
than intended. As an example, CLRF STATUS will set
the Z bit and leave the remaining Status bits
unchanged (‘000u u1uu’).
REGISTER 5-2:
U-0
For other instructions that do not affect Status bits, see
the instruction set summaries in Table 24-2 and
Table 24-3.
Note:
The C and DC bits operate as the borrow
and digit borrow bits, respectively, in
subtraction.
STATUS: STATUS REGISTER
U-0
—
It is recommended that only BCF, BSF, SWAPF, MOVFF
and MOVWF instructions are used to alter the STATUS
register, because these instructions do not affect the Z,
C, DC, OV or N bits in the STATUS register.
—
U-0
—
R/W-x
N
R/W-x
OV
R/W-x
R/W-x
R/W-x
(1)
Z
DC
bit 7
C(1)
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-5
Unimplemented: Read as ‘0’
bit 4
N: Negative bit
This bit is used for signed arithmetic (two’s complement). It indicates whether the result was negative
(ALU MSB = 1).
1 = Result was negative
0 = Result was positive
bit 3
OV: Overflow bit
This bit is used for signed arithmetic (two’s complement). It indicates an overflow of the 7-bit magnitude which causes the sign bit (bit 7 of the result) to change state.
1 = Overflow occurred for signed arithmetic (in this arithmetic operation)
0 = No overflow occurred
bit 2
Z: Zero bit
1 = The result of an arithmetic or logic operation is zero
0 = The result of an arithmetic or logic operation is not zero
bit 1
DC: Digit Carry/Borrow bit (ADDWF, ADDLW,SUBLW,SUBWF instructions)(1)
1 = A carry-out from the 4th low-order bit of the result occurred
0 = No carry-out from the 4th low-order bit of the result
bit 0
C: Carry/Borrow bit (ADDWF, ADDLW, SUBLW, SUBWF instructions)(1)
1 = A carry-out from the Most Significant bit of the result occurred
0 = No carry-out from the Most Significant bit of the result occurred
Note 1:
For Borrow, the polarity is reversed. A subtraction is executed by adding the two’s complement of the
second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high-order or low-order
bit of the source register.
DS41303G-page 82
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
5.4
Data Addressing Modes
Note:
The execution of some instructions in the
core PIC18 instruction set are changed
when the PIC18 extended instruction set is
enabled. See Section 5.5 “Data Memory
and the Extended Instruction Set” for
more information.
While the program memory can be addressed in only
one way – through the program counter – information
in the data memory space can be addressed in several
ways. For most instructions, the addressing mode is
fixed. Other instructions may use up to three modes,
depending on which operands are used and whether or
not the extended instruction set is enabled.
The addressing modes are:
•
•
•
•
Inherent
Literal
Direct
Indirect
A few instructions, such as MOVFF, include the entire
12-bit address (either source or destination) in their
opcodes. In these cases, the BSR is ignored entirely.
The destination of the operation’s results is determined
by the destination bit ‘d’. When ‘d’ is ‘1’, the results are
stored back in the source register, overwriting its original contents. When ‘d’ is ‘0’, the results are stored in
the W register. Instructions without the ‘d’ argument
have a destination that is implicit in the instruction; their
destination is either the target register being operated
on or the W register.
5.4.3
An additional addressing mode, Indexed Literal Offset,
is available when the extended instruction set is
enabled (XINST Configuration bit = 1). Its operation is
discussed in greater detail in Section 5.5.1 “Indexed
Addressing with Literal Offset”.
5.4.1
The Access RAM bit ‘a’ determines how the address is
interpreted. When ‘a’ is ‘1’, the contents of the BSR
(Section 5.3.1 “Bank Select Register (BSR)”) are
used with the address to determine the complete 12-bit
address of the register. When ‘a’ is ‘0’, the address is
interpreted as being a register in the Access Bank.
Addressing that uses the Access RAM is sometimes
also known as Direct Forced Addressing mode.
INHERENT AND LITERAL
ADDRESSING
Many PIC18 control instructions do not need any argument at all; they either perform an operation that globally affects the device or they operate implicitly on one
register. This addressing mode is known as Inherent
Addressing. Examples include SLEEP, RESET and DAW.
Other instructions work in a similar way but require an
additional explicit argument in the opcode. This is
known as Literal Addressing mode because they
require some literal value as an argument. Examples
include ADDLW and MOVLW, which respectively, add or
move a literal value to the W register. Other examples
include CALL and GOTO, which include a 20-bit
program memory address.
Indirect addressing allows the user to access a location
in data memory without giving a fixed address in the
instruction. This is done by using File Select Registers
(FSRs) as pointers to the locations which are to be read
or written. Since the FSRs are themselves located in
RAM as Special File Registers, they can also be
directly manipulated under program control. This
makes FSRs very useful in implementing data structures, such as tables and arrays in data memory.
The registers for indirect addressing are also
implemented with Indirect File Operands (INDFs) that
permit automatic manipulation of the pointer value with
auto-incrementing, auto-decrementing or offsetting
with another value. This allows for efficient code, using
loops, such as the example of clearing an entire RAM
bank in Example 5-5.
EXAMPLE 5-5:
NEXT
5.4.2
INDIRECT ADDRESSING
LFSR
CLRF
DIRECT ADDRESSING
Direct addressing specifies all or part of the source
and/or destination address of the operation within the
opcode itself. The options are specified by the
arguments accompanying the instruction.
BTFSS
BRA
CONTINUE
HOW TO CLEAR RAM
(BANK 1) USING
INDIRECT ADDRESSING
FSR0, 100h ;
POSTINC0
; Clear INDF
; register then
; inc pointer
FSR0H, 1
; All done with
; Bank1?
NEXT
; NO, clear next
; YES, continue
In the core PIC18 instruction set, bit-oriented and byteoriented instructions use some version of direct
addressing by default. All of these instructions include
some 8-bit literal address as their Least Significant
Byte. This address specifies either a register address in
one of the banks of data RAM (Section 5.3.3 “General
Purpose Register File”) or a location in the Access
Bank (Section 5.3.2 “Access Bank”) as the data
source for the instruction.
 2010 Microchip Technology Inc.
DS41303G-page 83
PIC18F2XK20/4XK20
5.4.3.1
FSR Registers and the INDF
Operand
5.4.3.2
At the core of indirect addressing are three sets of registers: FSR0, FSR1 and FSR2. Each represents a pair
of 8-bit registers, FSRnH and FSRnL. Each FSR pair
holds a 12-bit value, therefore the four upper bits of the
FSRnH register are not used. The 12-bit FSR value can
address the entire range of the data memory in a linear
fashion. The FSR register pairs, then, serve as pointers
to data memory locations.
In addition to the INDF operand, each FSR register pair
also has four additional indirect operands. Like INDF,
these are “virtual” registers which cannot be directly
read or written. Accessing these registers actually
accesses the location to which the associated FSR
register pair points, and also performs a specific action
on the FSR value. They are:
• POSTDEC: accesses the location to which the
FSR points, then automatically decrements the
FSR by 1 afterwards
• POSTINC: accesses the location to which the
FSR points, then automatically increments the
FSR by 1 afterwards
• PREINC: automatically increments the FSR by 1,
then uses the location to which the FSR points in
the operation
• PLUSW: adds the signed value of the W register
(range of -127 to 128) to that of the FSR and uses
the location to which the result points in the
operation.
Indirect addressing is accomplished with a set of
Indirect File Operands, INDF0 through INDF2. These
can be thought of as “virtual” registers: they are
mapped in the SFR space but are not physically
implemented. Reading or writing to a particular INDF
register actually accesses its corresponding FSR
register pair. A read from INDF1, for example, reads
the data at the address indicated by FSR1H:FSR1L.
Instructions that use the INDF registers as operands
actually use the contents of their corresponding FSR as
a pointer to the instruction’s target. The INDF operand
is just a convenient way of using the pointer.
Because indirect addressing uses a full 12-bit address,
data RAM banking is not necessary. Thus, the current
contents of the BSR and the Access RAM bit have no
effect on determining the target address.
FIGURE 5-10:
FSR Registers and POSTINC,
POSTDEC, PREINC and PLUSW
In this context, accessing an INDF register uses the
value in the associated FSR register without changing
it. Similarly, accessing a PLUSW register gives the
FSR value an offset by that in the W register; however,
neither W nor the FSR is actually changed in the
operation. Accessing the other virtual registers
changes the value of the FSR register.
INDIRECT ADDRESSING
000h
Using an instruction with one of the
indirect addressing registers as the
operand....
Bank 0
ADDWF, INDF1, 1
100h
Bank 1
200h
Bank 2
...uses the 12-bit address stored in
the FSR pair associated with that
register....
300h
FSR1H:FSR1L
7
0
x x x x 1 1 1 0
7
0
Bank 3
through
Bank 13
1 1 0 0 1 1 0 0
...to determine the data memory
location to be used in that operation.
In this case, the FSR1 pair contains
ECCh. This means the contents of
location ECCh will be added to that
of the W register and stored back in
ECCh.
E00h
Bank 14
F00h
Bank 15
FFFh
Data Memory
DS41303G-page 84
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
Operations on the FSRs with POSTDEC, POSTINC
and PREINC affect the entire register pair; that is, rollovers of the FSRnL register from FFh to 00h carry over
to the FSRnH register. On the other hand, results of
these operations do not change the value of any flags
in the STATUS register (e.g., Z, N, OV, etc.).
The PLUSW register can be used to implement a form
of indexed addressing in the data memory space. By
manipulating the value in the W register, users can
reach addresses that are fixed offsets from pointer
addresses. In some applications, this can be used to
implement some powerful program control structure,
such as software stacks, inside of data memory.
5.4.3.3
Operations by FSRs on FSRs
Indirect addressing operations that target other FSRs
or virtual registers represent special cases. For
example, using an FSR to point to one of the virtual
registers will not result in successful operations. As a
specific case, assume that FSR0H:FSR0L contains
FE7h, the address of INDF1. Attempts to read the
value of the INDF1 using INDF0 as an operand will
return 00h. Attempts to write to INDF1 using INDF0 as
the operand will result in a NOP.
On the other hand, using the virtual registers to write to
an FSR pair may not occur as planned. In these cases,
the value will be written to the FSR pair but without any
incrementing or decrementing. Thus, writing to either
the INDF2 or POSTDEC2 register will write the same
value to the FSR2H:FSR2L.
Since the FSRs are physical registers mapped in the
SFR space, they can be manipulated through all direct
operations. Users should proceed cautiously when
working on these registers, particularly if their code
uses indirect addressing.
Similarly, operations by indirect addressing are generally
permitted on all other SFRs. Users should exercise the
appropriate caution that they do not inadvertently change
settings that might affect the operation of the device.
5.5
Data Memory and the Extended
Instruction Set
Enabling the PIC18 extended instruction set (XINST
Configuration bit = 1) significantly changes certain
aspects of data memory and its addressing. Specifically, the use of the Access Bank for many of the core
PIC18 instructions is different; this is due to the introduction of a new addressing mode for the data memory
space.
5.5.1
INDEXED ADDRESSING WITH
LITERAL OFFSET
Enabling the PIC18 extended instruction set changes
the behavior of indirect addressing using the FSR2
register pair within Access RAM. Under the proper
conditions, instructions that use the Access Bank – that
is, most bit-oriented and byte-oriented instructions –
can invoke a form of indexed addressing using an
offset specified in the instruction. This special
addressing mode is known as Indexed Addressing with
Literal Offset, or Indexed Literal Offset mode.
When using the extended instruction set, this
addressing mode requires the following:
• The use of the Access Bank is forced (‘a’ = 0) and
• The file address argument is less than or equal to
5Fh.
Under these conditions, the file address of the
instruction is not interpreted as the lower byte of an
address (used with the BSR in direct addressing), or as
an 8-bit address in the Access Bank. Instead, the value
is interpreted as an offset value to an Address Pointer,
specified by FSR2. The offset and the contents of
FSR2 are added to obtain the target address of the
operation.
5.5.2
INSTRUCTIONS AFFECTED BY
INDEXED LITERAL OFFSET MODE
Any of the core PIC18 instructions that can use direct
addressing are potentially affected by the Indexed
Literal Offset Addressing mode. This includes all
byte-oriented and bit-oriented instructions, or almost
one-half of the standard PIC18 instruction set.
Instructions that only use Inherent or Literal Addressing
modes are unaffected.
Additionally, byte-oriented and bit-oriented instructions
are not affected if they do not use the Access Bank
(Access RAM bit is ‘1’), or include a file address of 60h
or above. Instructions meeting these criteria will
continue to execute as before. A comparison of the
different possible addressing modes when the
extended instruction set is enabled is shown in
Figure 5-11.
Those who desire to use byte-oriented or bit-oriented
instructions in the Indexed Literal Offset mode should
note the changes to assembler syntax for this mode.
This is described in more detail in Section 24.2.1
“Extended Instruction Syntax”.
What does not change is just as important. The size of
the data memory space is unchanged, as well as its
linear addressing. The SFR map remains the same.
Core PIC18 instructions can still operate in both Direct
and Indirect Addressing mode; inherent and literal
instructions do not change at all. Indirect addressing
with FSR0 and FSR1 also remain unchanged.
 2010 Microchip Technology Inc.
DS41303G-page 85
PIC18F2XK20/4XK20
FIGURE 5-11:
COMPARING ADDRESSING OPTIONS FOR BIT-ORIENTED AND
BYTE-ORIENTED INSTRUCTIONS (EXTENDED INSTRUCTION SET ENABLED)
EXAMPLE INSTRUCTION: ADDWF, f, d, a (Opcode: 0010 01da ffff ffff)
When ‘a’ = 0 and f  60h:
The instruction executes in
Direct Forced mode. ‘f’ is interpreted as a location in the
Access RAM between 060h
and 0FFh. This is the same as
locations F60h to FFFh
(Bank 15) of data memory.
Locations below 60h are not
available in this addressing
mode.
000h
060h
Bank 0
100h
00h
Bank 1
through
Bank 14
60h
Valid range
for ‘f’
Access RAM
F00h
FFh
Bank 15
F60h
SFRs
FFFh
Data Memory
When ‘a’ = 0 and f5Fh:
The instruction executes in
Indexed Literal Offset mode. ‘f’
is interpreted as an offset to the
address value in FSR2. The
two are added together to
obtain the address of the target
register for the instruction. The
address can be anywhere in
the data memory space.
Note that in this mode, the
correct syntax is now:
ADDWF [k], d
where ‘k’ is the same as ‘f’.
000h
060h
Bank 0
100h
001001da ffffffff
Bank 1
through
Bank 14
FSR2H
FSR2L
F00h
Bank 15
F60h
SFRs
FFFh
Data Memory
When ‘a’ = 1 (all values of f):
The instruction executes in
Direct mode (also known as
Direct Long mode). ‘f’ is interpreted as a location in one of
the 16 banks of the data
memory space. The bank is
designated by the Bank Select
Register (BSR). The address
can be in any implemented
bank in the data memory
space.
BSR
00000000
000h
060h
Bank 0
100h
Bank 1
through
Bank 14
001001da ffffffff
F00h
Bank 15
F60h
SFRs
FFFh
Data Memory
DS41303G-page 86
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
5.5.3
MAPPING THE ACCESS BANK IN
INDEXED LITERAL OFFSET MODE
The use of Indexed Literal Offset Addressing mode
effectively changes how the first 96 locations of Access
RAM (00h to 5Fh) are mapped. Rather than containing
just the contents of the bottom section of Bank 0, this
mode maps the contents from a user defined “window”
that can be located anywhere in the data memory
space. The value of FSR2 establishes the lower boundary of the addresses mapped into the window, while the
upper boundary is defined by FSR2 plus 95 (5Fh).
Addresses in the Access RAM above 5Fh are mapped
as previously described (see Section 5.3.2 “Access
Bank”). An example of Access Bank remapping in this
addressing mode is shown in Figure 5-12.
FIGURE 5-12:
Remapping of the Access Bank applies only to operations using the Indexed Literal Offset mode. Operations
that use the BSR (Access RAM bit is ‘1’) will continue
to use direct addressing as before.
5.6
PIC18 Instruction Execution and
the Extended Instruction Set
Enabling the extended instruction set adds eight
additional commands to the existing PIC18 instruction
set. These instructions are executed as described in
Section 24.2 “Extended Instruction Set”.
REMAPPING THE ACCESS BANK WITH INDEXED LITERAL OFFSET
ADDRESSING
Example Situation:
ADDWF f, d, a
FSR2H:FSR2L = 120h
Locations in the region
from the FSR2 pointer
(120h) to the pointer plus
05Fh (17Fh) are mapped
to the bottom of the
Access RAM (000h-05Fh).
000h
Bank 0
100h
120h
17Fh
200h
Bank 1
Window
Bank 1
00h
Bank 1 “Window”
5Fh
60h
Special File Registers at
F60h through FFFh are
mapped to 60h through
FFh, as usual.
Bank 2
through
Bank 14
Bank 0 addresses below
5Fh can still be addressed
by using the BSR.
SFRs
FFh
Access Bank
F00h
Bank 15
F60h
SFRs
FFFh
Data Memory
 2010 Microchip Technology Inc.
DS41303G-page 87
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 88
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
6.0
FLASH PROGRAM MEMORY
The Flash program memory is readable, writable and
erasable during normal operation over the entire VDD
range.
A read from program memory is executed one byte at
a time. A write to program memory is executed on
blocks of 64, 32 or 16 bytes at a time, depending on the
specific device (See Table 6-1). Program memory is
erased in blocks of 64 bytes at a time. The difference
between the write and erase block sizes requires from
1 to 4 block writes to restore the contents of a single
block erase. A bulk erase operation cannot be issued
from user code.
TABLE 6-1:
WRITE/ERASE BLOCK SIZES
Write Block
Size (bytes)
Erase Block
Size (bytes)
PIC18F43K20,
PIC18F23K20
16
64
PIC18F24K20,
PIC18F25K20,
PIC18F44K20,
PIC18F45K20
32
64
PIC18F26K20,
PIC18F46K20
64
64
Device
Writing or erasing program memory will cease
instruction fetches until the operation is complete. The
program memory cannot be accessed during the write
or erase, therefore, code cannot execute. An internal
programming timer terminates program memory writes
and erases.
FIGURE 6-1:
A value written to program memory does not need to be
a valid instruction. Executing a program memory
location that forms an invalid instruction results in a
NOP.
6.1
Table Reads and Table Writes
In order to read and write program memory, there are
two operations that allow the processor to move bytes
between the program memory space and the data RAM:
• Table Read (TBLRD)
• Table Write (TBLWT)
The program memory space is 16 bits wide, while the
data RAM space is 8 bits wide. Table reads and table
writes move data between these two memory spaces
through an 8-bit register (TABLAT).
The table read operation retrieves one byte of data
directly from program memory and places it into the
TABLAT register. Figure 6-1 shows the operation of a
table read.
The table write operation stores one byte of data from the
TABLAT register into a write block holding register. The
procedure to write the contents of the holding registers
into program memory is detailed in Section 6.5 “Writing
to Flash Program Memory”. Figure 6-2 shows the
operation of a table write with program memory and data
RAM.
Table operations work with byte entities. Tables containing data, rather than program instructions, are not
required to be word aligned. Therefore, a table can start
and end at any byte address. If a table write is being
used to write executable code into program memory,
program instructions will need to be word aligned.
TABLE READ OPERATION
Instruction: TBLRD*
Program Memory
Table Pointer(1)
TBLPTRU
TBLPTRH
Table Latch (8-bit)
TBLPTRL
TABLAT
Program Memory
(TBLPTR)
Note 1: Table Pointer register points to a byte in program memory.
 2010 Microchip Technology Inc.
DS41303G-page 89
PIC18F2XK20/4XK20
FIGURE 6-2:
TABLE WRITE OPERATION
Instruction: TBLWT*
Program Memory
Table Pointer(1)
TBLPTRU
TBLPTRH
Holding Registers
Table Latch (8-bit)
TBLPTRL
TABLAT
Program Memory
(TBLPTR<MSBs>)
Note 1: During table writes the Table Pointer does not point directly to Program Memory. The LSBs of TBLPRTL
actually point to an address within the write block holding registers. The MSBs of the Table Pointer determine where the write block will eventually be written. The process for writing the holding registers to the
program memory array is discussed in Section 6.5 “Writing to Flash Program Memory”.
6.2
Control Registers
Several control registers are used in conjunction with
the TBLRD and TBLWT instructions. These include the:
•
•
•
•
EECON1 register
EECON2 register
TABLAT register
TBLPTR registers
6.2.1
EECON1 AND EECON2 REGISTERS
The EECON1 register (Register 6-1) is the control
register for memory accesses. The EECON2 register is
not a physical register; it is used exclusively in the
memory write and erase sequences. Reading
EECON2 will read all ‘0’s.
The EEPGD control bit determines if the access will be
a program or data EEPROM memory access. When
EEPGD is clear, any subsequent operations will
operate on the data EEPROM memory. When EEPGD
is set, any subsequent operations will operate on the
program memory.
The CFGS control bit determines if the access will be
to the Configuration/Calibration registers or to program
memory/data EEPROM memory. When CFGS is set,
subsequent operations will operate on Configuration
registers regardless of EEPGD (see Section 23.0
“Special Features of the CPU”). When CFGS is clear,
memory selection access is determined by EEPGD.
DS41303G-page 90
The FREE bit allows the program memory erase operation. When FREE is set, an erase operation is initiated
on the next WR command. When FREE is clear, only
writes are enabled.
The WREN bit, when set, will allow a write operation.
The WREN bit is clear on power-up.
The WRERR bit is set by hardware when the WR bit is
set and cleared when the internal programming timer
expires and the write operation is complete.
Note:
During normal operation, the WRERR is
read as ‘1’. This can indicate that a write
operation was prematurely terminated by
a Reset, or a write operation was
attempted improperly.
The WR control bit initiates write operations. The WR
bit cannot be cleared, only set, by firmware. Then WR
bit is cleared by hardware at the completion of the write
operation.
Note:
The EEIF interrupt flag bit of the PIR2
register is set when the write is complete.
The EEIF flag stays set until cleared by
firmware.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 6-1:
EECON1: DATA EEPROM CONTROL 1 REGISTER
R/W-x
R/W-x
U-0
R/W-0
R/W-x
R/W-0
R/S-0
R/S-0
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
S = Bit can be set by software, but not cleared
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘0’ = Bit is cleared
‘1’ = Bit is set
x = Bit is unknown
bit 7
EEPGD: Flash Program or Data EEPROM Memory Select bit
1 = Access Flash program memory
0 = Access data EEPROM memory
bit 6
CFGS: Flash Program/Data EEPROM or Configuration Select bit
1 = Access Configuration registers
0 = Access Flash program or data EEPROM memory
bit 5
Unimplemented: Read as ‘0’
bit 4
FREE: Flash Row (Block) Erase Enable bit
1 = Erase the program memory block addressed by TBLPTR on the next WR command
(cleared by completion of erase operation)
0 = Perform write-only
bit 3
WRERR: Flash Program/Data EEPROM Error Flag bit(1)
1 = A write operation is prematurely terminated (any Reset during self-timed programming in normal
operation, or an improper write attempt)
0 = The write operation completed
bit 2
WREN: Flash Program/Data EEPROM Write Enable bit
1 = Allows write cycles to Flash program/data EEPROM
0 = Inhibits write cycles to Flash program/data EEPROM
bit 1
WR: Write Control bit
1 = Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle.
(The operation is self-timed and the bit is cleared by hardware once write is complete.
The WR bit can only be set (not cleared) by software.)
0 = Write cycle to the EEPROM is complete
bit 0
RD: Read Control bit
1 = Initiates an EEPROM read (Read takes one cycle. RD is cleared by hardware. The RD bit can only
be set (not cleared) by software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.)
0 = Does not initiate an EEPROM read
Note 1:
When a WRERR occurs, the EEPGD and CFGS bits are not cleared. This allows tracing of the
error condition.
 2010 Microchip Technology Inc.
DS41303G-page 91
PIC18F2XK20/4XK20
6.2.2
TABLAT – TABLE LATCH REGISTER
When a TBLRD is executed, all 22 bits of the TBLPTR
determine which byte is read from program memory
directly into the TABLAT register.
The Table Latch (TABLAT) is an 8-bit register mapped
into the SFR space. The Table Latch register is used to
hold 8-bit data during data transfers between program
memory and data RAM.
6.2.3
When a TBLWT is executed the byte in the TABLAT register is written, not to Flash memory but, to a holding
register in preparation for a program memory write. The
holding registers constitute a write block which varies
depending on the device (See Table 6-1).The 3, 4, or 5
LSbs of the TBLPTRL register determine which specific
address within the holding register block is written to.
The MSBs of the Table Pointer have no effect during
TBLWT operations.
TBLPTR – TABLE POINTER
REGISTER
The Table Pointer (TBLPTR) register addresses a byte
within the program memory. The TBLPTR is comprised
of three SFR registers: Table Pointer Upper Byte,
Table Pointer High Byte and Table Pointer Low Byte
(TBLPTRU:TBLPTRH:TBLPTRL). These three registers join to form a 22-bit wide pointer. The low-order
21 bits allow the device to address up to 2 Mbytes of
program memory space. The 22nd bit allows access to
the device ID, the user ID and the Configuration bits.
When a program memory write is executed the entire
holding register block is written to the Flash memory at
the address determined by the MSbs of the TBLPTR.
The 3, 4, or 5 LSBs are ignored during Flash memory
writes. For more detail, see Section 6.5 “Writing to
Flash Program Memory”.
The Table Pointer register, TBLPTR, is used by the
TBLRD and TBLWT instructions. These instructions can
update the TBLPTR in one of four ways based on the
table operation. These operations are shown in
Table 6-2. These operations on the TBLPTR affect only
the low-order 21 bits.
6.2.4
When an erase of program memory is executed, the
16 MSbs
of
the
Table
Pointer
register
(TBLPTR<21:6>) point to the 64-byte block that will be
erased. The Least Significant bits (TBLPTR<5:0>) are
ignored.
Figure 6-3 describes the relevant boundaries of
TBLPTR based on Flash program memory operations.
TABLE POINTER BOUNDARIES
TBLPTR is used in reads, writes and erases of the
Flash program memory.
TABLE 6-2:
TABLE POINTER OPERATIONS WITH TBLRD AND TBLWT INSTRUCTIONS
Example
Operation on Table Pointer
TBLRD*
TBLWT*
TBLPTR is not modified
TBLRD*+
TBLWT*+
TBLPTR is incremented after the read/write
TBLRD*TBLWT*-
TBLPTR is decremented after the read/write
TBLRD+*
TBLWT+*
TBLPTR is incremented before the read/write
FIGURE 6-3:
21
TABLE POINTER BOUNDARIES BASED ON OPERATION
TBLPTRU
16
15
TBLPTRH
8
7
TABLE ERASE/WRITE
TBLPTR<21:n+1>(1)
TBLPTRL
0
TABLE WRITE
TBLPTR<n:0>(1)
TABLE READ – TBLPTR<21:0>
Note 1: n = 3, 4, 5, or 6 for block sizes of 8, 16, 32 or 64 bytes, respectively.
DS41303G-page 92
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
6.3
Reading the Flash Program
Memory
The TBLRD instruction retrieves data from program
memory and places it into data RAM. Table reads from
program memory are performed one byte at a time.
The internal program memory is typically organized by
words. The Least Significant bit of the address selects
between the high and low bytes of the word. Figure 6-4
shows the interface between the internal program
memory and the TABLAT.
TBLPTR points to a byte address in program space.
Executing TBLRD places the byte pointed to into
TABLAT. In addition, TBLPTR can be modified
automatically for the next table read operation.
FIGURE 6-4:
READS FROM FLASH PROGRAM MEMORY
Program Memory
(Even Byte Address)
(Odd Byte Address)
TBLPTR = xxxxx1
Instruction Register
(IR)
EXAMPLE 6-1:
FETCH
TBLRD
TBLPTR = xxxxx0
TABLAT
Read Register
READING A FLASH PROGRAM MEMORY WORD
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; Load TBLPTR with the base
; address of the word
READ_WORD
TBLRD*+
MOVF
MOVWF
TBLRD*+
MOVFW
MOVF
TABLAT, W
WORD_EVEN
TABLAT, W
WORD_ODD
 2010 Microchip Technology Inc.
; read into TABLAT and increment
; get data
; read into TABLAT and increment
; get data
DS41303G-page 93
PIC18F2XK20/4XK20
6.4
Erasing Flash Program Memory
The minimum erase block is 32 words or 64 bytes. Only
through the use of an external programmer, or through
ICSP™ control, can larger blocks of program memory
be bulk erased. Word erase in the Flash array is not
supported.
When initiating an erase sequence from the Microcontroller itself, a block of 64 bytes of program memory is
erased. The Most Significant 16 bits of the
TBLPTR<21:6> point to the block being erased. The
TBLPTR<5:0> bits are ignored.
The EECON1 register commands the erase operation.
The EEPGD bit must be set to point to the Flash program memory. The WREN bit must be set to enable
write operations. The FREE bit is set to select an erase
operation.
The write initiate sequence for EECON2, shown as
steps 4 through 6 in Section 6.4.1 “Flash Program
Memory Erase Sequence”, is used to guard against
accidental writes. This is sometimes referred to as a
long write.
6.4.1
FLASH PROGRAM MEMORY
ERASE SEQUENCE
The sequence of events for erasing a block of internal
program memory is:
1.
2.
3.
4.
5.
6.
7.
8.
Load Table Pointer register with address of
block being erased.
Set the EECON1 register for the erase operation:
• set EEPGD bit to point to program memory;
• clear the CFGS bit to access program memory;
• set WREN bit to enable writes;
• set FREE bit to enable the erase.
Disable interrupts.
Write 55h to EECON2.
Write 0AAh to EECON2.
Set the WR bit. This will begin the block erase
cycle.
The CPU will stall for duration of the erase
(about 2 ms using internal timer).
Re-enable interrupts.
A long write is necessary for erasing the internal Flash.
Instruction execution is halted during the long write
cycle. The long write is terminated by the internal programming timer.
EXAMPLE 6-2:
ERASING A FLASH PROGRAM MEMORY BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; load TBLPTR with the base
; address of the memory block
BSF
BCF
BSF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BSF
EECON1,
EECON1,
EECON1,
EECON1,
INTCON,
55h
EECON2
0AAh
EECON2
EECON1,
INTCON,
;
;
;
;
;
ERASE_BLOCK
Required
Sequence
DS41303G-page 94
EEPGD
CFGS
WREN
FREE
GIE
point to Flash program memory
access Flash program memory
enable write to memory
enable block Erase operation
disable interrupts
; write 55h
WR
GIE
; write 0AAh
; start erase (CPU stall)
; re-enable interrupts
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
6.5
Writing to Flash Program Memory
The programming block size is 16, 32 or 64 bytes,
depending on the device (See Table 6-1). Word or byte
programming is not supported.
Table writes are used internally to load the holding
registers needed to program the Flash memory. There
are only as many holding registers as there are bytes
in a write block (See Table 6-1).
Since the Table Latch (TABLAT) is only a single byte,
the TBLWT instruction may need to be executed 16, 32
or 64 times, depending on the device, for each programming operation. All of the table write operations
will essentially be short writes because only the holding
registers are written. After all the holding registers have
been written, the programming operation of that block
of memory is started by configuring the EECON1 register for a program memory write and performing the
long write sequence.
FIGURE 6-5:
The long write is necessary for programming the internal Flash. Instruction execution is halted during a long
write cycle. The long write will be terminated by the
internal programming timer.
The EEPROM on-chip timer controls the write time.
The write/erase voltages are generated by an on-chip
charge pump, rated to operate over the voltage range
of the device.
Note:
The default value of the holding registers on
device Resets and after write operations is
FFh. A write of FFh to a holding register
does not modify that byte. This means that
individual bytes of program memory may be
modified, provided that the change does not
attempt to change any bit from a ‘0’ to a ‘1’.
When modifying individual bytes, it is not
necessary to load all holding registers
before executing a long write operation.
TABLE WRITES TO FLASH PROGRAM MEMORY
TABLAT
Write Register
8
8
TBLPTR = xxxx00
TBLPTR = xxxx01
Holding Register
8
TBLPTR = xxxxYY(1)
TBLPTR = xxxx02
Holding Register
8
Holding Register
Holding Register
Program Memory
Note 1: YY = x7, xF, or 1F for 8, 16 or 32 byte write blocks, respectively.
6.5.1
FLASH PROGRAM MEMORY WRITE
SEQUENCE
The sequence of events for programming an internal
program memory location should be:
1.
2.
3.
4.
5.
6.
7.
Read 64 bytes into RAM.
Update data values in RAM as necessary.
Load Table Pointer register with address being
erased.
Execute the block erase procedure.
Load Table Pointer register with address of first
byte being written.
Write the 16, 32 or 64 byte block into the holding
registers with auto-increment.
Set the EECON1 register for the write operation:
• set EEPGD bit to point to program memory;
• clear the CFGS bit to access program memory;
• set WREN to enable byte writes.
 2010 Microchip Technology Inc.
8.
9.
10.
11.
12.
Disable interrupts.
Write 55h to EECON2.
Write 0AAh to EECON2.
Set the WR bit. This will begin the write cycle.
The CPU will stall for duration of the write (about
2 ms using internal timer).
13. Re-enable interrupts.
14. Repeat steps 6 to 13 for each block until all 64
bytes are written.
15. Verify the memory (table read).
This procedure will require about 6 ms to update each
write block of memory. An example of the required code
is given in Example 6-3.
Note:
Before setting the WR bit, the Table
Pointer address needs to be within the
intended address range of the bytes in the
holding registers.
DS41303G-page 95
PIC18F2XK20/4XK20
EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
D'64’
COUNTER
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; number of bytes in erase block
TBLRD*+
MOVF
MOVWF
DECFSZ
BRA
TABLAT, W
POSTINC0
COUNTER
READ_BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
NEW_DATA_LOW
POSTINC0
NEW_DATA_HIGH
INDF0
; point to buffer
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BCF
BSF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BSF
TBLRD*MOVLW
MOVWF
MOVLW
MOVWF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
EECON1, FREE
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
INTCON, GIE
; load TBLPTR with the base
; address of the memory block
MOVLW
MOVWF
MOVLW
MOVWF
BlockSize
COUNTER
D’64’/BlockSize
COUNTER2
MOVF
MOVWF
TBLWT+*
POSTINC0, W
TABLAT
; point to buffer
; Load TBLPTR with the base
; address of the memory block
READ_BLOCK
;
;
;
;
;
read into TABLAT, and inc
get data
store data
done?
repeat
MODIFY_WORD
; update buffer word
ERASE_BLOCK
Required
Sequence
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
;
;
;
;
;
point to Flash program memory
access Flash program memory
enable write to memory
enable Erase operation
disable interrupts
; write 55h
;
;
;
;
;
write 0AAh
start erase (CPU stall)
re-enable interrupts
dummy read decrement
point to buffer
WRITE_BUFFER_BACK
; number of bytes in holding register
; number of write blocks in 64 bytes
WRITE_BYTE_TO_HREGS
DS41303G-page 96
;
;
;
;
get low byte of buffer data
present data to table latch
write data, perform a short write
to internal TBLWT holding register.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
DECFSZ
BRA
COUNTER
WRITE_WORD_TO_HREGS
; loop until holding registers are full
BSF
BCF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
DCFSZ
BRA
BSF
BCF
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
COUNTER2
WRITE_BYTE_TO_HREGS
INTCON, GIE
EECON1, WREN
;
;
;
;
PROGRAM_MEMORY
Required
Sequence
6.5.2
WRITE VERIFY
UNEXPECTED TERMINATION OF
WRITE OPERATION
If a write is terminated by an unplanned event, such as
loss of power or an unexpected Reset, the memory
location just programmed should be verified and
reprogrammed if needed. If the write operation is
interrupted by a MCLR Reset or a WDT Time-out Reset
during normal operation, the WRERR bit will be set
which the user can check to decide whether a rewrite
of the location(s) is needed.
TABLE 6-3:
; write 55h
;
;
;
;
;
;
write 0AAh
start program (CPU stall)
repeat for remaining write blocks
re-enable interrupts
disable write to memory
6.5.4
Depending on the application, good programming
practice may dictate that the value written to the
memory should be verified against the original value.
This should be used in applications where excessive
writes can stress bits near the specification limit.
6.5.3
point to Flash program memory
access Flash program memory
enable write to memory
disable interrupts
PROTECTION AGAINST
SPURIOUS WRITES
To protect against spurious writes to Flash program
memory, the write initiate sequence must also be
followed. See Section 23.0 “Special Features of the
CPU” for more detail.
6.6
Flash Program Operation During
Code Protection
See Section 23.3 “Program Verification and Code
Protection” for details on code protection of Flash
program memory.
REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY
Name
Bit 7
Bit 6
Bit 5
TBLPTRU
—
—
bit 21
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Program Memory Table Pointer Upper Byte (TBLPTR<20:16>)
Reset
Values on
page
59
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>)
59
TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>)
59
TABLAT
Program Memory Table Latch
INTCON
GIE/GIEH PEIE/GIEL TMR0IE
59
EECON2
EEPROM Control Register 2 (not a physical register)
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
61
EECON1
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
61
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
 2010 Microchip Technology Inc.
DS41303G-page 97
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 98
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
7.0
DATA EEPROM MEMORY
The data EEPROM is a nonvolatile memory array, separate from the data RAM and program memory, which
is used for long-term storage of program data. It is not
directly mapped in either the register file or program
memory space but is indirectly addressed through the
Special Function Registers (SFRs). The EEPROM is
readable and writable during normal operation over the
entire VDD range.
Four SFRs are used to read and write to the data
EEPROM as well as the program memory. They are:
•
•
•
•
•
EECON1
EECON2
EEDATA
EEADR
EEADRH
The data EEPROM allows byte read and write. When
interfacing to the data memory block, EEDATA holds
the 8-bit data for read/write and the EEADR:EEADRH
register pair hold the address of the EEPROM location
being accessed.
The EEPROM data memory is rated for high erase/write
cycle endurance. A byte write automatically erases the
location and writes the new data (erase-before-write).
The write time is controlled by an on-chip timer; it will
vary with voltage and temperature as well as from chipto-chip. Please refer to parameter D122 (Table 26.10 in
Section 26.0 “Electrical Characteristics”) for exact
limits.
7.1
EEADR and EEADRH Registers
The EEADR register is used to address the data
EEPROM for read and write operations. The 8-bit
range of the register can address a memory range of
256 bytes (00h to FFh). The EEADRH register expands
the range to 1024 bytes by adding an additional two
address bits.
7.2
EECON1 and EECON2 Registers
Access to the data EEPROM is controlled by two
registers: EECON1 and EECON2. These are the same
registers which control access to the program memory
and are used in a similar manner for the data
EEPROM.
 2010 Microchip Technology Inc.
The EECON1 register (Register 7-1) is the control register for data and program memory access. Control bit
EEPGD determines if the access will be to program or
data EEPROM memory. When the EEPGD bit is clear,
operations will access the data EEPROM memory.
When the EEPGD bit is set, program memory is
accessed.
Control bit, CFGS, determines if the access will be to
the Configuration registers or to program memory/data
EEPROM memory. When the CFGS bit is set,
subsequent operations access Configuration registers.
When the CFGS bit is clear, the EEPGD bit selects
either program Flash or data EEPROM memory.
The WREN bit, when set, will allow a write operation.
On power-up, the WREN bit is clear.
The WRERR bit is set by hardware when the WR bit is
set and cleared when the internal programming timer
expires and the write operation is complete.
Note:
During normal operation, the WRERR
may read as ‘1’. This can indicate that a
write operation was prematurely terminated by a Reset, or a write operation was
attempted improperly.
The WR control bit initiates write operations. The bit
can be set but not cleared by software. It is cleared only
by hardware at the completion of the write operation.
Note:
The EEIF interrupt flag bit of the PIR2
register is set when the write is complete.
It must be cleared by software.
Control bits, RD and WR, start read and erase/write
operations, respectively. These bits are set by firmware
and cleared by hardware at the completion of the
operation.
The RD bit cannot be set when accessing program
memory (EEPGD = 1). Program memory is read using
table read instructions. See Section 6.1 “Table Reads
and Table Writes” regarding table reads.
The EECON2 register is not a physical register. It is
used exclusively in the memory write and erase
sequences. Reading EECON2 will read all ‘0’s.
DS41303G-page 99
PIC18F2XK20/4XK20
REGISTER 7-1:
EECON1: DATA EEPROM CONTROL 1 REGISTER
R/W-x
R/W-x
U-0
R/W-0
R/W-x
R/W-0
R/S-0
R/S-0
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
S = Bit can be set by software, but not cleared
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘0’ = Bit is cleared
‘1’ = Bit is set
x = Bit is unknown
bit 7
EEPGD: Flash Program or Data EEPROM Memory Select bit
1 = Access Flash program memory
0 = Access data EEPROM memory
bit 6
CFGS: Flash Program/Data EEPROM or Configuration Select bit
1 = Access Configuration registers
0 = Access Flash program or data EEPROM memory
bit 5
Unimplemented: Read as ‘0’
bit 4
FREE: Flash Row (Block) Erase Enable bit
1 = Erase the program memory block addressed by TBLPTR on the next WR command
(cleared by completion of erase operation)
0 = Perform write-only
bit 3
WRERR: Flash Program/Data EEPROM Error Flag bit(1)
1 = A write operation is prematurely terminated (any Reset during self-timed programming in normal
operation, or an improper write attempt)
0 = The write operation completed
bit 2
WREN: Flash Program/Data EEPROM Write Enable bit
1 = Allows write cycles to Flash program/data EEPROM
0 = Inhibits write cycles to Flash program/data EEPROM
bit 1
WR: Write Control bit
1 = Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle.
(The operation is self-timed and the bit is cleared by hardware once write is complete.
The WR bit can only be set (not cleared) by software.)
0 = Write cycle to the EEPROM is complete
bit 0
RD: Read Control bit
1 = Initiates an EEPROM read (Read takes one cycle. RD is cleared by hardware. The RD bit can only
be set (not cleared) by software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.)
0 = Does not initiate an EEPROM read
Note 1:
When a WRERR occurs, the EEPGD and CFGS bits are not cleared. This allows tracing of the
error condition.
DS41303G-page 100
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
7.3
Reading the Data EEPROM
Memory
To read a data memory location, the user must write
the address to the EEADR register, clear the EEPGD
control bit of the EECON1 register and then set control
bit, RD. The data is available on the very next instruction cycle; therefore, the EEDATA register can be read
by the next instruction. EEDATA will hold this value until
another read operation, or until it is written to by the
user (during a write operation).
The basic process is shown in Example 7-1.
7.4
Writing to the Data EEPROM
Memory
Additionally, the WREN bit in EECON1 must be set to
enable writes. This mechanism prevents accidental
writes to data EEPROM due to unexpected code
execution (i.e., runaway programs). The WREN bit
should be kept clear at all times, except when updating
the EEPROM. The WREN bit is not cleared by
hardware.
After a write sequence has been initiated, EECON1,
EEADR and EEDATA cannot be modified. The WR bit
will be inhibited from being set unless the WREN bit is
set. Both WR and WREN cannot be set with the same
instruction.
At the completion of the write cycle, the WR bit is
cleared by hardware and the EEPROM Interrupt Flag
bit, EEIF, is set. The user may either enable this
interrupt or poll this bit. EEIF must be cleared by
software.
To write an EEPROM data location, the address must
first be written to the EEADR register and the data written to the EEDATA register. The sequence in
Example 7-2 must be followed to initiate the write cycle.
7.5
The write will not begin if this sequence is not exactly
followed (write 55h to EECON2, write 0AAh to
EECON2, then set WR bit) for each byte. It is strongly
recommended that interrupts be disabled during this
code segment.
Depending on the application, good programming
practice may dictate that the value written to the
memory should be verified against the original value.
This should be used in applications where excessive
writes can stress bits near the specification limit.
EXAMPLE 7-1:
MOVLW
MOVWF
BCF
BCF
BSF
MOVF
DATA EEPROM READ
DATA_EE_ADDR
EEADR
EECON1, EEPGD
EECON1, CFGS
EECON1, RD
EEDATA, W
EXAMPLE 7-2:
Required
Sequence
Write Verify
;
;
;
;
;
;
Data Memory Address to read
Point to DATA memory
Access EEPROM
EEPROM Read
W = EEDATA
DATA EEPROM WRITE
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BCF
BCF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BSF
DATA_EE_ADDR_LOW
EEADR
DATA_EE_ADDR_HI
EEADRH
DATA_EE_DATA
EEDATA
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
INTCON, GIE
;
;
;
;
;
;
;
;
;
;
;
;
;
;
;
;
BCF
EECON1, WREN
; User code execution
; Disable writes on write complete (EEIF set)
 2010 Microchip Technology Inc.
Data Memory Address to write
Data Memory Value to write
Point to DATA memory
Access EEPROM
Enable writes
Disable Interrupts
Write 55h
Write 0AAh
Set WR bit to begin write
Enable Interrupts
DS41303G-page 101
PIC18F2XK20/4XK20
7.6
Operation During Code-Protect
Data EEPROM memory has its own code-protect bits
in Configuration Words. External read and write
operations are disabled if code protection is enabled.
The microcontroller itself can both read and write to the
internal data EEPROM, regardless of the state of the
code-protect Configuration bit. Refer to Section 23.0
“Special Features of the CPU” for additional
information.
7.7
Protection Against Spurious Write
There are conditions when the user may not want to
write to the data EEPROM memory. To protect against
spurious EEPROM writes, various mechanisms have
been implemented. On power-up, the WREN bit is
cleared. In addition, writes to the EEPROM are blocked
during the Power-up Timer period (TPWRT,
parameter 33).
The write initiate sequence and the WREN bit together
help prevent an accidental write during brown-out,
power glitch or software malfunction.
7.8
The data EEPROM is a high-endurance, byte
addressable array that has been optimized for the
storage of frequently changing information (e.g.,
program variables or other data that are updated often).
When variables in one section change frequently, while
variables in another section do not change, it is possible
to exceed the total number of write cycles to the
EEPROM (specification D124) without exceeding the
total number of write cycles to a single byte (specification
D120). If this is the case, then an array refresh must be
performed. For this reason, variables that change
infrequently (such as constants, IDs, calibration, etc.)
should be stored in Flash program memory.
A simple data EEPROM refresh routine is shown in
Example 7-3.
Note:
EXAMPLE 7-3:
If data EEPROM is only used to store
constants and/or data that changes rarely,
an array refresh is likely not required. See
specification.
DATA EEPROM REFRESH ROUTINE
CLRF
BCF
BCF
BCF
BSF
EEADR
EECON1,
EECON1,
INTCON,
EECON1,
BSF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BTFSC
BRA
INCFSZ
BRA
EECON1, RD
55h
EECON2
0AAh
EECON2
EECON1, WR
EECON1, WR
$-2
EEADR, F
LOOP
BCF
BSF
EECON1, WREN
INTCON, GIE
CFGS
EEPGD
GIE
WREN
Loop
DS41303G-page 102
Using the Data EEPROM
;
;
;
;
;
;
;
;
;
;
;
;
;
Start at address 0
Set for memory
Set for Data EEPROM
Disable interrupts
Enable writes
Loop to refresh array
Read current address
Write 55h
Write 0AAh
Set WR bit to begin write
Wait for write to complete
; Increment address
; Not zero, do it again
; Disable writes
; Enable interrupts
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 7-1:
Name
REGISTERS ASSOCIATED WITH DATA EEPROM MEMORY
Bit 7
Bit 6
INTCON
GIE/GIEH
PEIE/GIEL
EEADR
EEADR7
EEADR6
—
—
EEADRH(1)
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
EEADR5 EEADR4 EEADR3 EEADR2 EEADR1 EEADR0
—
—
—
EEDATA
EEPROM Data Register
EECON2
EEPROM Control Register 2 (not a physical register)
—
EEADR9 EEADR8
Reset
Values
on page
59
61
61
61
61
EECON1
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
61
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
Note 1: PIC18F26K20/PIC18F46K20 only.
 2010 Microchip Technology Inc.
DS41303G-page 103
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 104
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
8.0
8 x 8 HARDWARE MULTIPLIER
8.1
Introduction
EXAMPLE 8-1:
MOVF
MULWF
All PIC18 devices include an 8 x 8 hardware multiplier
as part of the ALU. The multiplier performs an unsigned
operation and yields a 16-bit result that is stored in the
product register pair, PRODH:PRODL. The multiplier’s
operation does not affect any flags in the STATUS
register.
ARG1, W
ARG2
;
; ARG1 * ARG2 ->
; PRODH:PRODL
EXAMPLE 8-2:
Making multiplication a hardware operation allows it to
be completed in a single instruction cycle. This has the
advantages of higher computational throughput and
reduced code size for multiplication algorithms and
allows the PIC18 devices to be used in many applications previously reserved for digital signal processors.
A comparison of various hardware and software
multiply operations, along with the savings in memory
and execution time, is shown in Table 8-1.
8.2
8 x 8 UNSIGNED
MULTIPLY ROUTINE
8 x 8 SIGNED MULTIPLY
ROUTINE
MOVF
MULWF
ARG1, W
ARG2
BTFSC
SUBWF
ARG2, SB
PRODH, F
MOVF
BTFSC
SUBWF
ARG2, W
ARG1, SB
PRODH, F
;
;
;
;
;
ARG1 * ARG2 ->
PRODH:PRODL
Test Sign Bit
PRODH = PRODH
- ARG1
; Test Sign Bit
; PRODH = PRODH
;
- ARG2
Operation
Example 8-1 shows the instruction sequence for an 8 x 8
unsigned multiplication. Only one instruction is required
when one of the arguments is already loaded in the
WREG register.
Example 8-2 shows the sequence to do an 8 x 8 signed
multiplication. To account for the sign bits of the arguments, each argument’s Most Significant bit (MSb) is
tested and the appropriate subtractions are done.
TABLE 8-1:
PERFORMANCE COMPARISON FOR VARIOUS MULTIPLY OPERATIONS
Routine
8 x 8 unsigned
8 x 8 signed
16 x 16 unsigned
16 x 16 signed
Program
Memory
(Words)
Cycles
(Max)
Without hardware multiply
13
Hardware multiply
1
Without hardware multiply
33
Hardware multiply
6
Without hardware multiply
Hardware multiply
Multiply Method
Time
@ 40 MHz
@ 10 MHz
@ 4 MHz
69
6.9 s
27.6 s
69 s
1
100 ns
400 ns
1 s
91
9.1 s
36.4 s
91 s
6
600 ns
2.4 s
6 s
21
242
24.2 s
96.8 s
242 s
28
28
2.8 s
11.2 s
28 s
Without hardware multiply
52
254
25.4 s
102.6 s
254 s
Hardware multiply
35
40
4.0 s
16.0 s
40 s
 2010 Microchip Technology Inc.
DS41303G-page 105
PIC18F2XK20/4XK20
Example 8-3 shows the sequence to do a 16 x 16
unsigned multiplication. Equation 8-1 shows the
algorithm that is used. The 32-bit result is stored in four
registers (RES<3:0>).
EQUATION 8-1:
RES3:RES0
=
=
16 x 16 UNSIGNED
MULTIPLICATION
ALGORITHM
ARG1H:ARG1L  ARG2H:ARG2L
(ARG1H  ARG2H  216) +
(ARG1H  ARG2L  28) +
(ARG1L  ARG2H  28) +
(ARG1L  ARG2L)
EXAMPLE 8-3:
EQUATION 8-2:
RES3:RES0 = ARG1H:ARG1L  ARG2H:ARG2L
= (ARG1H  ARG2H  216) +
(ARG1H  ARG2L  28) +
(ARG1L  ARG2H  28) +
(ARG1L  ARG2L) +
(-1  ARG2H<7>  ARG1H:ARG1L  216) +
(-1  ARG1H<7>  ARG2H:ARG2L  216)
EXAMPLE 8-4:
16 x 16 UNSIGNED
MULTIPLY ROUTINE
MOVF
MULWF
ARG1L, W
ARG2L
MOVFF
MOVFF
PRODH, RES1
PRODL, RES0
MOVF
MULWF
ARG1H, W
ARG2H
MOVFF
MOVFF
PRODH, RES3
PRODL, RES2
MOVF
MULWF
ARG1L, W
ARG2H
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
PRODL, W
RES1, F
PRODH, W
RES2, F
WREG
RES3, F
MOVF
MULWF
ARG1H, W
ARG2L
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
PRODL, W
RES1, F
PRODH, W
RES2, F
WREG
RES3, F
; ARG1L * ARG2L->
; PRODH:PRODL
;
;
ARG1L * ARG2H->
PRODH:PRODL
Add cross
products
ARG1H * ARG2L->
PRODH:PRODL
Add cross
products
Example 8-4 shows the sequence to do a 16 x 16
signed multiply. Equation 8-2 shows the algorithm
used. The 32-bit result is stored in four registers
(RES<3:0>). To account for the sign bits of the arguments, the MSb for each argument pair is tested and
the appropriate subtractions are done.
DS41303G-page 106
ARG1L, W
ARG2L
MOVFF
MOVFF
PRODH, RES1
PRODL, RES0
MOVF
MULWF
ARG1H, W
ARG2H
MOVFF
MOVFF
PRODH, RES3
PRODL, RES2
MOVF
MULWF
ARG1L, W
ARG2H
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
PRODL, W
RES1, F
PRODH, W
RES2, F
WREG
RES3, F
MOVF
MULWF
ARG1H, W
ARG2L
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
PRODL, W
RES1, F
PRODH, W
RES2, F
WREG
RES3, F
BTFSS
BRA
MOVF
SUBWF
MOVF
SUBWFB
ARG2H, 7
SIGN_ARG1
ARG1L, W
RES2
ARG1H, W
RES3
; ARG2H:ARG2L neg?
; no, check ARG1
;
;
;
ARG1H, 7
CONT_CODE
ARG2L, W
RES2
ARG2H, W
RES3
; ARG1H:ARG1L neg?
; no, done
;
;
;
; ARG1L * ARG2L ->
; PRODH:PRODL
;
;
; ARG1H * ARG2H ->
; PRODH:PRODL
;
;
;
;
;
;
;
;
;
;
ARG1L * ARG2H ->
PRODH:PRODL
Add cross
products
;
;
;
;
;
;
;
;
;
;
;
MOVF
MULWF
;
;
;
;
;
;
;
;
;
;
16 x 16 SIGNED
MULTIPLY ROUTINE
;
;
; ARG1H * ARG2H->
; PRODH:PRODL
;
;
16 x 16 SIGNED
MULTIPLICATION
ALGORITHM
;
;
;
;
;
;
;
;
;
ARG1H * ARG2L ->
PRODH:PRODL
Add cross
products
;
;
SIGN_ARG1
BTFSS
BRA
MOVF
SUBWF
MOVF
SUBWFB
;
CONT_CODE
:
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
9.0
INTERRUPTS
The PIC18F2XK20/4XK20 devices have multiple
interrupt sources and an interrupt priority feature that
allows most interrupt sources to be assigned a high
priority level or a low priority level. The high priority
interrupt vector is at 0008h and the low priority interrupt
vector is at 0018h. A high priority interrupt event will
interrupt a low priority interrupt that may be in progress.
There are ten registers which are used to control
interrupt operation. These registers are:
•
•
•
•
•
•
•
RCON
INTCON
INTCON2
INTCON3
PIR1, PIR2
PIE1, PIE2
IPR1, IPR2
It is recommended that the Microchip header files supplied with MPLAB® IDE be used for the symbolic bit
names in these registers. This allows the assembler/
compiler to automatically take care of the placement of
these bits within the specified register.
In general, interrupt sources have three bits to control
their operation. They are:
• Flag bit to indicate that an interrupt event
occurred
• Enable bit that allows program execution to
branch to the interrupt vector address when the
flag bit is set
• Priority bit to select high priority or low priority
9.1
Mid-Range Compatibility
When the IPEN bit is cleared (default state), the interrupt
priority feature is disabled and interrupts are compatible
with PIC® microcontroller mid-range devices. In
Compatibility mode, the interrupt priority bits of the IPRx
registers have no effect. The PEIE bit of the INTCON
register is the global interrupt enable for the peripherals.
The PEIE bit disables only the peripheral interrupt
sources and enables the peripheral interrupt sources
when the GIE bit is also set. The GIE bit of the INTCON
register is the global interrupt enable which enables all
non-peripheral interrupt sources and disables all
interrupt sources, including the peripherals. All interrupts
branch to address 0008h in Compatibility mode.
9.2
The interrupt priority feature is enabled by setting the
IPEN bit of the RCON register. When interrupt priority
is enabled the GIE and PEIE global interrupt enable
bits of Compatibility mode are replaced by the GIEH
high priority, and GIEL low priority, global interrupt
enables. When set, the GIEH bit of the INTCON register enables all interrupts that have their associated
IPRx register or INTCONx register priority bit set (high
priority). When clear, the GIEH bit disables all interrupt
sources including those selected as low priority. When
clear, the GIEL bit of the INTCON register disables only
the interrupts that have their associated priority bit
cleared (low priority). When set, the GIEL bit enables
the low priority sources when the GIEH bit is also set.
When the interrupt flag, enable bit and appropriate
global interrupt enable bit are all set, the interrupt will
vector immediately to address 0008h for high priority,
or 0018h for low priority, depending on level of the
interrupting source’s priority bit. Individual interrupts
can be disabled through their corresponding interrupt
enable bits.
9.3
Interrupt Response
When an interrupt is responded to, the global interrupt
enable bit is cleared to disable further interrupts. The
GIE bit is the global interrupt enable when the IPEN bit
is cleared. When the IPEN bit is set, enabling interrupt
priority levels, the GIEH bit is the high priority global
interrupt enable and the GIEL bit is the low priority
global interrupt enable. High priority interrupt sources
can interrupt a low priority interrupt. Low priority
interrupts are not processed while high priority
interrupts are in progress.
The return address is pushed onto the stack and the
PC is loaded with the interrupt vector address (0008h
or 0018h). Once in the Interrupt Service Routine, the
source(s) of the interrupt can be determined by polling
the interrupt flag bits in the INTCONx and PIRx
registers. The interrupt flag bits must be cleared by
software before re-enabling interrupts to avoid
repeating the same interrupt.
The “return from interrupt” instruction, RETFIE, exits
the interrupt routine and sets the GIE bit (GIEH or GIEL
if priority levels are used), which re-enables interrupts.
For external interrupt events, such as the INT pins or
the PORTB interrupt-on-change, the interrupt latency
will be three to four instruction cycles. The exact
latency is the same for one-cycle or two-cycle
instructions. Individual interrupt flag bits are set,
regardless of the status of their corresponding enable
bits or the global interrupt enable bit.
Note:
 2010 Microchip Technology Inc.
Interrupt Priority
Do not use the MOVFF instruction to modify
any of the interrupt control registers while
any interrupt is enabled. Doing so may
cause erratic microcontroller behavior.
DS41303G-page 107
PIC18F2XK20/4XK20
FIGURE 9-1:
PIC18 INTERRUPT LOGIC
TMR0IF
TMR0IE
TMR0IP
RBIF
RBIE
RBIP
INT0IF
INT0IE
Wake-up if in
Idle or Sleep modes
(1)
Interrupt to CPU
Vector to Location
0008h
INT1IF
INT1IE
INT1IP
INT2IF
INT2IE
INT2IP
SSPIF
SSPIE
SSPIP
GIEH/GIE
ADIF
ADIE
ADIP
IPEN
RCIF
RCIE
RCIP
IPEN
GIEL/PEIE
IPEN
Additional Peripheral Interrupts
High Priority Interrupt Generation
Low Priority Interrupt Generation
SSPIF
SSPIE
SSPIP
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
Interrupt to CPU
Vector to Location
0018h
TMR0IF
TMR0IE
TMR0IP
RBIF
RBIE
RBIP
(1)
GIEH/GIE
GIEL/PEIE
INT1IF
INT1IE
INT1IP
Additional Peripheral Interrupts
INT2IF
INT2IE
INT2IP
Note
1:
The RBIF interrupt also requires the individual pin IOCB enables.
DS41303G-page 108
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
9.4
INTCON Registers
Note:
The INTCON registers are readable and writable
registers, which contain various enable, priority and
flag bits.
REGISTER 9-1:
Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the global
enable bit. User software should ensure
the appropriate interrupt flag bits are clear
prior to enabling an interrupt. This feature
allows for software polling.
INTCON: INTERRUPT CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-x
GIE/GIEH
PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
GIE/GIEH: Global Interrupt Enable bit
When IPEN = 0:
1 = Enables all unmasked interrupts
0 = Disables all interrupts including peripherals
When IPEN = 1:
1 = Enables all high priority interrupts
0 = Disables all interrupts including low priority.
bit 6
PEIE/GIEL: Peripheral Interrupt Enable bit
When IPEN = 0:
1 = Enables all unmasked peripheral interrupts
0 = Disables all peripheral interrupts
When IPEN = 1:
1 = Enables all low priority interrupts
0 = Disables all low priority interrupts
bit 5
TMR0IE: TMR0 Overflow Interrupt Enable bit
1 = Enables the TMR0 overflow interrupt
0 = Disables the TMR0 overflow interrupt
bit 4
INT0IE: INT0 External Interrupt Enable bit
1 = Enables the INT0 external interrupt
0 = Disables the INT0 external interrupt
bit 3
RBIE: RB Port Change Interrupt Enable bit(2)
1 = Enables the RB port change interrupt
0 = Disables the RB port change interrupt
bit 2
TMR0IF: TMR0 Overflow Interrupt Flag bit
1 = TMR0 register has overflowed (must be cleared by software)
0 = TMR0 register did not overflow
bit 1
INT0IF: INT0 External Interrupt Flag bit
1 = The INT0 external interrupt occurred (must be cleared by software)
0 = The INT0 external interrupt did not occur
bit 0
RBIF: RB Port Change Interrupt Flag bit(1)
1 = At least one of the RB<7:4> pins changed state (must be cleared by software)
0 = None of the RB<7:4> pins have changed state
Note 1:
2:
x = Bit is unknown
A mismatch condition will continue to set the RBIF bit. Reading PORTB will end the
mismatch condition and allow the bit to be cleared.
RB port change interrupts also require the individual pin IOCB enables.
 2010 Microchip Technology Inc.
DS41303G-page 109
PIC18F2XK20/4XK20
REGISTER 9-2:
INTCON2: INTERRUPT CONTROL 2 REGISTER
R/W-1
R/W-1
R/W-1
R/W-1
U-0
R/W-1
U-0
R/W-1
RBPU
INTEDG0
INTEDG1
INTEDG2
—
TMR0IP
—
RBIP
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
RBPU: PORTB Pull-up Enable bit
1 = All PORTB pull-ups are disabled
0 = PORTB pull-ups are enabled provided that the pin is an input and the corresponding WPUB bit is
set.
bit 6
INTEDG0: External Interrupt 0 Edge Select bit
1 = Interrupt on rising edge
0 = Interrupt on falling edge
bit 5
INTEDG1: External Interrupt 1 Edge Select bit
1 = Interrupt on rising edge
0 = Interrupt on falling edge
bit 4
INTEDG2: External Interrupt 2 Edge Select bit
1 = Interrupt on rising edge
0 = Interrupt on falling edge
bit 3
Unimplemented: Read as ‘0’
bit 2
TMR0IP: TMR0 Overflow Interrupt Priority bit
1 = High priority
0 = Low priority
bit 1
Unimplemented: Read as ‘0’
bit 0
RBIP: RB Port Change Interrupt Priority bit
1 = High priority
0 = Low priority
Note:
Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the global
enable bit. User software should ensure
the appropriate interrupt flag bits are clear
prior to enabling an interrupt. This feature
allows for software polling.
DS41303G-page 110
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 9-3:
INTCON3: INTERRUPT CONTROL 3 REGISTER
R/W-1
R/W-1
U-0
R/W-0
R/W-0
U-0
R/W-0
R/W-0
INT2IP
INT1IP
—
INT2IE
INT1IE
—
INT2IF
INT1IF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
INT2IP: INT2 External Interrupt Priority bit
1 = High priority
0 = Low priority
bit 6
INT1IP: INT1 External Interrupt Priority bit
1 = High priority
0 = Low priority
bit 5
Unimplemented: Read as ‘0’
bit 4
INT2IE: INT2 External Interrupt Enable bit
1 = Enables the INT2 external interrupt
0 = Disables the INT2 external interrupt
bit 3
INT1IE: INT1 External Interrupt Enable bit
1 = Enables the INT1 external interrupt
0 = Disables the INT1 external interrupt
bit 2
Unimplemented: Read as ‘0’
bit 1
INT2IF: INT2 External Interrupt Flag bit
1 = The INT2 external interrupt occurred (must be cleared by software)
0 = The INT2 external interrupt did not occur
bit 0
INT1IF: INT1 External Interrupt Flag bit
1 = The INT1 external interrupt occurred (must be cleared by software)
0 = The INT1 external interrupt did not occur
Note:
x = Bit is unknown
Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the global
enable bit. User software should ensure
the appropriate interrupt flag bits are clear
prior to enabling an interrupt. This feature
allows for software polling.
 2010 Microchip Technology Inc.
DS41303G-page 111
PIC18F2XK20/4XK20
9.5
PIR Registers
The PIR registers contain the individual flag bits for the
peripheral interrupts. Due to the number of peripheral
interrupt sources, there are two Peripheral Interrupt
Request Flag registers (PIR1 and PIR2).
Note 1: Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the Global
Interrupt Enable bit, GIE of the INTCON
register.
2: User software should ensure the appropriate interrupt flag bits are cleared prior to
enabling an interrupt and after servicing
that interrupt.
REGISTER 9-4:
PIR1: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 1
R/W-0
R/W-0
R-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
PSPIF: Parallel Slave Port Read/Write Interrupt Flag bit(1)
1 = A read or a write operation has taken place (must be cleared by software)
0 = No read or write has occurred
bit 6
ADIF: A/D Converter Interrupt Flag bit
1 = An A/D conversion completed (must be cleared by software)
0 = The A/D conversion is not complete or has not been started
bit 5
RCIF: EUSART Receive Interrupt Flag bit
1 = The EUSART receive buffer, RCREG, is full (cleared when RCREG is read)
0 = The EUSART receive buffer is empty
bit 4
TXIF: EUSART Transmit Interrupt Flag bit
1 = The EUSART transmit buffer, TXREG, is empty (cleared when TXREG is written)
0 = The EUSART transmit buffer is full
bit 3
SSPIF: Master Synchronous Serial Port Interrupt Flag bit
1 = The transmission/reception is complete (must be cleared by software)
0 = Waiting to transmit/receive
bit 2
CCP1IF: CCP1 Interrupt Flag bit
Capture mode:
1 = A TMR1 register capture occurred (must be cleared by software)
0 = No TMR1 register capture occurred
Compare mode:
1 = A TMR1 register compare match occurred (must be cleared by software)
0 = No TMR1 register compare match occurred
PWM mode:
Unused in this mode
bit 1
TMR2IF: TMR2 to PR2 Match Interrupt Flag bit
1 = TMR2 to PR2 match occurred (must be cleared by software)
0 = No TMR2 to PR2 match occurred
bit 0
TMR1IF: TMR1 Overflow Interrupt Flag bit
1 = TMR1 register overflowed (must be cleared by software)
0 = TMR1 register did not overflow
Note 1: The PSPIF bit is unimplemented on 28-pin devices and will read as ‘0’.
DS41303G-page 112
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 9-5:
PIR2: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 2
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
OSCFIF: Oscillator Fail Interrupt Flag bit
1 = Device oscillator failed, clock input has changed to HFINTOSC (must be cleared by software)
0 = Device clock operating
bit 6
C1IF: Comparator C1 Interrupt Flag bit
1 = Comparator C1 output has changed (must be cleared by software)
0 = Comparator C1 output has not changed
bit 5
C2IF: Comparator C2 Interrupt Flag bit
1 = Comparator C2 output has changed (must be cleared by software)
0 = Comparator C2 output has not changed
bit 4
EEIF: Data EEPROM/Flash Write Operation Interrupt Flag bit
1 = The write operation is complete (must be cleared by software)
0 = The write operation is not complete or has not been started
bit 3
BCLIF: Bus Collision Interrupt Flag bit
1 = A bus collision occurred (must be cleared by software)
0 = No bus collision occurred
bit 2
HLVDIF: Low-Voltage Detect Interrupt Flag bit
1 = A low-voltage condition occurred (direction determined by the VDIRMAG bit of the
HLVDCON register)
0 = A low-voltage condition has not occurred
bit 1
TMR3IF: TMR3 Overflow Interrupt Flag bit
1 = TMR3 register overflowed (must be cleared by software)
0 = TMR3 register did not overflow
bit 0
CCP2IF: CCP2 Interrupt Flag bit
Capture mode:
1 = A TMR1 register capture occurred (must be cleared by software)
0 = No TMR1 register capture occurred
Compare mode:
1 = A TMR1 register compare match occurred (must be cleared by software)
0 = No TMR1 register compare match occurred
PWM mode:
Unused in this mode.
 2010 Microchip Technology Inc.
DS41303G-page 113
PIC18F2XK20/4XK20
9.6
PIE Registers
The PIE registers contain the individual enable bits for
the peripheral interrupts. Due to the number of peripheral interrupt sources, there are two Peripheral Interrupt
Enable registers (PIE1 and PIE2). When IPEN = 0, the
PEIE bit must be set to enable any of these peripheral
interrupts.
REGISTER 9-6:
PIE1: PERIPHERAL INTERRUPT ENABLE (FLAG) REGISTER 1
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
PSPIE: Parallel Slave Port Read/Write Interrupt Enable bit(1)
1 = Enables the PSP read/write interrupt
0 = Disables the PSP read/write interrupt
bit 6
ADIE: A/D Converter Interrupt Enable bit
1 = Enables the A/D interrupt
0 = Disables the A/D interrupt
bit 5
RCIE: EUSART Receive Interrupt Enable bit
1 = Enables the EUSART receive interrupt
0 = Disables the EUSART receive interrupt
bit 4
TXIE: EUSART Transmit Interrupt Enable bit
1 = Enables the EUSART transmit interrupt
0 = Disables the EUSART transmit interrupt
bit 3
SSPIE: Master Synchronous Serial Port Interrupt Enable bit
1 = Enables the MSSP interrupt
0 = Disables the MSSP interrupt
bit 2
CCP1IE: CCP1 Interrupt Enable bit
1 = Enables the CCP1 interrupt
0 = Disables the CCP1 interrupt
bit 1
TMR2IE: TMR2 to PR2 Match Interrupt Enable bit
1 = Enables the TMR2 to PR2 match interrupt
0 = Disables the TMR2 to PR2 match interrupt
bit 0
TMR1IE: TMR1 Overflow Interrupt Enable bit
1 = Enables the TMR1 overflow interrupt
0 = Disables the TMR1 overflow interrupt
Note 1:
x = Bit is unknown
The PSPIE bit is unimplemented on 28-pin devices and will read as ‘0’.
DS41303G-page 114
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 9-7:
PIE2: PERIPHERAL INTERRUPT ENABLE (FLAG) REGISTER 2
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
OSCFIE: Oscillator Fail Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 6
C1IE: Comparator C1 Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 5
C2IE: Comparator C2 Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 4
EEIE: Data EEPROM/Flash Write Operation Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 3
BCLIE: Bus Collision Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 2
HLVDIE: Low-Voltage Detect Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 1
TMR3IE: TMR3 Overflow Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 0
CCP2IE: CCP2 Interrupt Enable bit
1 = Enabled
0 = Disabled
 2010 Microchip Technology Inc.
x = Bit is unknown
DS41303G-page 115
PIC18F2XK20/4XK20
9.7
IPR Registers
The IPR registers contain the individual priority bits for the
peripheral interrupts. Due to the number of peripheral
interrupt sources, there are two Peripheral Interrupt
Priority registers (IPR1 and IPR2). Using the priority bits
requires that the Interrupt Priority Enable (IPEN) bit be
set.
REGISTER 9-8:
IPR1: PERIPHERAL INTERRUPT PRIORITY REGISTER 1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
PSPIP: Parallel Slave Port Read/Write Interrupt Priority bit(1)
1 = High priority
0 = Low priority
bit 6
ADIP: A/D Converter Interrupt Priority bit
1 = High priority
0 = Low priority
bit 5
RCIP: EUSART Receive Interrupt Priority bit
1 = High priority
0 = Low priority
bit 4
TXIP: EUSART Transmit Interrupt Priority bit
x = Bit is unknown
1 = High priority
0 = Low priority
bit 3
SSPIP: Master Synchronous Serial Port Interrupt Priority bit
1 = High priority
0 = Low priority
bit 2
CCP1IP: CCP1 Interrupt Priority bit
1 = High priority
0 = Low priority
bit 1
TMR2IP: TMR2 to PR2 Match Interrupt Priority bit
1 = High priority
0 = Low priority
bit 0
TMR1IP: TMR1 Overflow Interrupt Priority bit
1 = High priority
0 = Low priority
Note 1: The PSPIF bit is unimplemented on 28-pin devices and will read as ‘0’.
DS41303G-page 116
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 9-9:
IPR2: PERIPHERAL INTERRUPT PRIORITY REGISTER 2
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
OSCFIP: Oscillator Fail Interrupt Priority bit
1 = High priority
0 = Low priority
bit 6
C1IP: Comparator C1 Interrupt Priority bit
1 = High priority
0 = Low priority
bit 5
C2IP: Comparator C2 Interrupt Priority bit
1 = High priority
0 = Low priority
bit 4
EEIP: Data EEPROM/Flash Write Operation Interrupt Priority bit
1 = High priority
0 = Low priority
bit 3
BCLIP: Bus Collision Interrupt Priority bit
1 = High priority
0 = Low priority
bit 2
HLVDIP: Low-Voltage Detect Interrupt Priority bit
1 = High priority
0 = Low priority
bit 1
TMR3IP: TMR3 Overflow Interrupt Priority bit
1 = High priority
0 = Low priority
bit 0
CCP2IP: CCP2 Interrupt Priority bit
1 = High priority
0 = Low priority
 2010 Microchip Technology Inc.
x = Bit is unknown
DS41303G-page 117
PIC18F2XK20/4XK20
9.8
RCON Register
The RCON register contains flag bits which are used to
determine the cause of the last Reset or wake-up from
Idle or Sleep modes. RCON also contains the IPEN bit
which enables interrupt priorities.
The operation of the SBOREN bit and the Reset flag
bits is discussed in more detail in Section 4.1 “RCON
Register”.
REGISTER 9-10:
R/W-0
IPEN
RCON: RESET CONTROL REGISTER
R/W-1
SBOREN
U-0
(1)
—
R/W-1
R-1
RI
TO
R-1
R/W-0
PD
(1)
R/W-0
POR
bit 7
BOR
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
IPEN: Interrupt Priority Enable bit
1 = Enable priority levels on interrupts
0 = Disable priority levels on interrupts (Mid-Range Compatibility mode)
bit 6
SBOREN: Software BOR Enable bit(1)
For details of bit operation, see Register 4-1.
bit 5
Unimplemented: Read as ‘0’
bit 4
RI: RESET Instruction Flag bit
For details of bit operation, see Register 4-1.
bit 3
TO: Watchdog Time-out Flag bit
For details of bit operation, see Register 4-1.
bit 2
PD: Power-down Detection Flag bit
For details of bit operation, see Register 4-1
bit 1
POR: Power-on Reset Status bit
For details of bit operation, see Register 4-1.
bit 0
BOR: Brown-out Reset Status bit
For details of bit operation, see Register 4-1.
Note 1: Actual Reset values are determined by device configuration and the nature of the device Reset.
See Register 4-1 for additional information.
DS41303G-page 118
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
9.9
INTn Pin Interrupts
9.10
External interrupts on the RB0/INT0, RB1/INT1 and
RB2/INT2 pins are edge-triggered. If the corresponding
INTEDGx bit in the INTCON2 register is set (= 1), the
interrupt is triggered by a rising edge; if the bit is clear,
the trigger is on the falling edge. When a valid edge
appears on the RBx/INTx pin, the corresponding flag
bit, INTxF, is set. This interrupt can be disabled by
clearing the corresponding enable bit, INTxE. Flag bit,
INTxF, must be cleared by software in the Interrupt
Service Routine before re-enabling the interrupt.
All external interrupts (INT0, INT1 and INT2) can wakeup the processor from Idle or Sleep modes if bit INTxE
was set prior to going into those modes. If the Global
Interrupt Enable bit, GIE, is set, the processor will
branch to the interrupt vector following wake-up.
Interrupt priority for INT1 and INT2 is determined by the
value contained in the interrupt priority bits, INT1IP and
INT2IP of the INTCON3 register. There is no priority bit
associated with INT0. It is always a high priority interrupt source.
TMR0 Interrupt
In 8-bit mode (which is the default), an overflow in the
TMR0 register (FFh  00h) will set flag bit, TMR0IF. In
16-bit mode, an overflow in the TMR0H:TMR0L register pair (FFFFh 0000h) will set TMR0IF. The interrupt
can be enabled/disabled by setting/clearing enable bit,
TMR0IE of the INTCON register. Interrupt priority for
Timer0 is determined by the value contained in the
interrupt priority bit, TMR0IP of the INTCON2 register.
See Section 12.0 “Timer0 Module” for further details
on the Timer0 module.
9.11
PORTB Interrupt-on-Change
An input change on PORTB<7:4> sets flag bit, RBIF of
the INTCON register. The interrupt can be enabled/
disabled by setting/clearing enable bit, RBIE of the
INTCON register. Pins must also be individually
enabled with the IOCB register. Interrupt priority for
PORTB interrupt-on-change is determined by the value
contained in the interrupt priority bit, RBIP of the
INTCON2 register.
9.12
Context Saving During Interrupts
During interrupts, the return PC address is saved on
the stack. Additionally, the WREG, STATUS and BSR
registers are saved on the fast return stack. If a fast
return from interrupt is not used (see Section 5.1.3
“Fast Register Stack”), the user may need to save the
WREG, STATUS and BSR registers on entry to the
Interrupt Service Routine. Depending on the user’s
application, other registers may also need to be saved.
Example 9-1 saves and restores the WREG, STATUS
and BSR registers during an Interrupt Service Routine.
EXAMPLE 9-1:
SAVING STATUS, WREG AND BSR REGISTERS IN RAM
MOVWF
W_TEMP
MOVFF
STATUS, STATUS_TEMP
MOVFF
BSR, BSR_TEMP
;
; USER ISR CODE
;
MOVFF
BSR_TEMP, BSR
MOVF
W_TEMP, W
MOVFF
STATUS_TEMP, STATUS
 2010 Microchip Technology Inc.
; W_TEMP is in virtual bank
; STATUS_TEMP located anywhere
; BSR_TMEP located anywhere
; Restore BSR
; Restore WREG
; Restore STATUS
DS41303G-page 119
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 120
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
10.0
I/O PORTS
Reading the PORTA register reads the status of the
pins, whereas writing to it, will write to the PORT latch.
Depending on the device selected and features
enabled, there are up to five ports available. Some pins
of the I/O ports are multiplexed with an alternate
function from the peripheral features on the device. In
general, when a peripheral is enabled, that pin may not
be used as a general purpose I/O pin.
Each port has three registers for its operation. These
registers are:
• TRIS register (data direction register)
• PORT register (reads the levels on the pins of the
device)
• LAT register (output latch)
The Data Latch (LAT register) is useful for read-modifywrite operations on the value that the I/O pins are
driving.
A simplified model of a generic I/O port, without the
interfaces to other peripherals, is shown in Figure 10-1.
FIGURE 10-1:
GENERIC I/O PORT
OPERATION
D
WR LAT
or Port
The other PORTA pins are multiplexed with analog
inputs, the analog VREF+ and VREF- inputs, and the
comparator voltage reference output. The operation of
pins RA<3:0> and RA5 as analog is selected by setting
the ANS<4:0> bits in the ANSEL register which is the
default setting after a Power-on Reset.
Pins RA0 through RA5 may also be used as comparator
inputs or outputs by setting the appropriate bits in the
CM1CON0 and CM2CON0 registers.
I/O pin(1)
CK
D
On a Power-on Reset, RA5 and RA<3:0>
are configured as analog inputs and read
as ‘0’. RA4 is configured as a digital input.
Q
Data Latch
WR TRIS
The RA4 pin is multiplexed with the Timer0 module
clock input and one of the comparator outputs to
become the RA4/T0CKI/C1OUT pin. Pins RA6 and
RA7 are multiplexed with the main oscillator pins; they
are enabled as oscillator or I/O pins by the selection of
the main oscillator in the Configuration register (see
Section 23.1 “Configuration Bits” for details). When
they are not used as port pins, RA6 and RA7 and their
associated TRIS and LAT bits are read as ‘0’.
Note:
RD LAT
Data
Bus
The Data Latch (LATA) register is also memory mapped.
Read-modify-write operations on the LATA register read
and write the latched output value for PORTA.
The RA4/T0CKI/C1OUT pin is a Schmitt Trigger input.
All other PORTA pins have TTL input levels and full
CMOS output drivers.
The TRISA register controls the drivers of the PORTA
pins, even when they are being used as analog inputs.
The user should ensure the bits in the TRISA register
are maintained set when using them as analog inputs.
Q
CK
TRIS Latch
Input
Buffer
RD TRIS
Q
D
EXAMPLE 10-1:
CLRF
PORTA
CLRF
LATA
MOVLW
MOVWF
MOVLW
E0h
ANSEL
0CFh
MOVWF
TRISA
ENEN
RD Port
Note 1:
10.1
I/O pins have diode protection to VDD and VSS.
PORTA, TRISA and LATA
Registers
INITIALIZING PORTA
;
;
;
;
;
;
;
;
;
;
;
;
;
Initialize PORTA by
clearing output
data latches
Alternate method
to clear output
data latches
Configure I/O
for digital inputs
Value used to
initialize data
direction
Set RA<3:0> as inputs
RA<5:4> as outputs
PORTA is an 8-bit wide, bidirectional port. The
corresponding data direction register is TRISA. Setting
a TRISA bit (= 1) will make the corresponding PORTA
pin an input (i.e., disable the output driver). Clearing a
TRISA bit (= 0) will make the corresponding PORTA
pin an output (i.e., enable the output driver and put the
contents of the output latch on the selected pin).
 2010 Microchip Technology Inc.
DS41303G-page 121
PIC18F2XK20/4XK20
TABLE 10-1:
PORTA I/O SUMMARY
Pin
Function
TRIS
Setting
I/O
I/O
Type
RA0/AN0/C12IN0-
RA0
0
O
DIG
LATA<0> data output; not affected by analog input.
1
I
TTL
PORTA<0> data input; disabled when analog input enabled.
AN0
1
I
ANA
ADC input channel 0. Default input configuration on POR; does not
affect digital output.
C12IN0-
1
I
ANA
Comparators C1 and C2 inverting input, channel 0. Analog select is
shared with ADC.
RA1
0
O
DIG
LATA<1> data output; not affected by analog input.
1
I
TTL
PORTA<1> data input; disabled when analog input enabled.
AN1
1
I
ANA
ADC input channel 1. Default input configuration on POR; does not
affect digital output.
C12IN1-
1
I
ANA
Comparators C1 and C2 inverting input, channel 1. Analog select is
shared with ADC.
RA2
0
O
DIG
LATA<2> data output; not affected by analog input. Disabled when
CVREF output enabled.
1
I
TTL
PORTA<2> data input. Disabled when analog functions enabled;
disabled when CVREF output enabled.
AN2
1
I
ANA
ADC input channel 2. Default input configuration on POR; not affected
by analog output.
C2IN+
1
I
ANA
Comparator C2 non-inverting input. Analog selection is shared with
ADC.
RA1/AN1/C12IN1-
RA2/AN2/C2IN+
VREF-/CVREF
RA3/AN3/C1IN+/
VREF+
RA4/T0CKI/C1OUT
VREF-
1
I
ANA
ADC and comparator voltage reference low input.
CVREF
x
O
ANA
Comparator voltage reference output. Enabling this feature disables
digital I/O.
RA3
0
O
DIG
LATA<3> data output; not affected by analog input.
1
I
TTL
PORTA<3> data input; disabled when analog input enabled.
AN3
1
I
ANA
A/D input channel 3. Default input configuration on POR.
C1IN+
1
I
ANA
Comparator C1 non-inverting input. Analog selection is shared with
ADC.
VREF+
1
I
ANA
ADC and comparator voltage reference high input.
RA4
0
O
DIG
LATA<4> data output.
1
I
ST
PORTA<4> data input; default configuration on POR.
1
I
ST
Timer0 clock input.
T0CKI
RA5/AN4/SS/
HLVDIN/C2OUT
OSC2/CLKOUT/
RA6
Legend:
Description
C1OUT
0
O
DIG
Comparator 1 output; takes priority over port data.
RA5
0
O
DIG
LATA<5> data output; not affected by analog input.
1
I
TTL
PORTA<5> data input; disabled when analog input enabled.
A/D input channel 4. Default configuration on POR.
AN4
1
I
ANA
SS
1
I
TTL
Slave select input for SSP (MSSP module).
HLVDIN
1
I
ANA
Low-Voltage Detect external trip point input.
C2OUT
0
O
DIG
Comparator 2 output; takes priority over port data.
RA6
0
O
DIG
LATA<6> data output. Enabled in RCIO, INTIO2 and ECIO modes only.
1
I
TTL
PORTA<6> data input. Enabled in RCIO, INTIO2 and ECIO modes
only.
OSC2
x
O
ANA
Main oscillator feedback output connection (XT, HS and LP modes).
CLKOUT
x
O
DIG
System cycle clock output (FOSC/4) in RC, INTIO1 and EC Oscillator
modes.
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x = Don’t care (TRIS bit does not affect port direction or is overridden for this option).
DS41303G-page 122
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 10-1:
PORTA I/O SUMMARY (CONTINUED)
Pin
Function
TRIS
Setting
I/O
I/O
Type
OSC1/CLKIN/RA7
RA7
0
O
DIG
Legend:
Description
LATA<7> data output. Disabled in external oscillator modes.
1
I
TTL
PORTA<7> data input. Disabled in external oscillator modes.
OSC1
x
I
ANA
Main oscillator input connection.
CLKIN
x
I
ANA
Main clock input connection.
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x = Don’t care (TRIS bit does not affect port direction or is overridden for this option).
TABLE 10-2:
SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
RA7(1)
RA6(1)
RA5
RA4
RA3
RA2
RA1
RA0
62
LATA
LATA7(1)
LATA6(1)
TRISA
TRISA7(1) TRISA6(1) PORTA Data Direction Control Register
Name
PORTA
ANSEL
SLRCON
PORTA Data Latch Register (Read and Write to Data Latch)
62
62
ANS7(2)
ANS6(2)
ANS5(2)
ANS4
ANS3
ANS2
ANS1
ANS0
62
—
—
—
SLRE(2)
SLRD(2)
SLRC
SLRB
SLRA
63
CM1CON0
C1ON
C1OUT
C1OE
C1POL
C1SP
C1R
C1CH1
C1CH0
62
CM2CON0
C2ON
C2OUT
C2OE
C2POL
C2SP
C2R
C2CH1
C2CH0
62
CVRCON
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
61
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTA.
Note 1: RA<7:6> and their associated latch and data direction bits are enabled as I/O pins based on oscillator
configuration; otherwise, they are read as ‘0’.
2: Not implemented on PIC18F2XK20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 123
PIC18F2XK20/4XK20
10.2
PORTB, TRISB and LATB
Registers
PORTB is an 8-bit wide, bidirectional port. The corresponding data direction register is TRISB. Setting a
TRISB bit (= 1) will make the corresponding PORTB
pin an input (i.e., disable the output driver). Clearing a
TRISB bit (= 0) will make the corresponding PORTB
pin an output (i.e., enable the output driver and put the
contents of the output latch on the selected pin).
The Data Latch register (LATB) is also memory
mapped. Read-modify-write operations on the LATB
register read and write the latched output value for
PORTB.
EXAMPLE 10-2:
CLRF
CLRF
CLRF
MOVLW
MOVWF
10.3
INITIALIZING PORTB
PORTB
; Initialize PORTB by
; clearing output
; data latches
LATB
; Alternate method
; to clear output
; data latches
ANSELH ; Set RB<4:0> as
; digital I/O pins
;(required if config bit
; PBADEN is set)
0CFh
; Value used to
; initialize data
; direction
TRISB
; Set RB<3:0> as inputs
; RB<5:4> as outputs
; RB<7:6> as inputs
Additional PORTB Pin Functions
PORTB pins RB<7:4> have an interrupt-on-change
option. All PORTB pins have a weak pull-up option. An
alternate CCP2 peripheral option is available on RB3.
10.3.1
On a Power-on Reset, RB<4:0> are
configured as analog inputs by default and
read as ‘0’; RB<7:5> are configured as
digital inputs.
When the PBADEN Configuration bit is set
to ‘1’, RB<4:0> will alternatively be
configured as digital inputs on POR.
DS41303G-page 124
INTERRUPT-ON-CHANGE
Four of the PORTB pins (RB<7:4>) are individually
configurable as interrupt-on-change pins. Control bits
in the IOCB register enable (when set) or disable (when
clear) the interrupt function for each pin.
When set, the RBIE bit of the INTCON register enables
interrupts on all pins which also have their corresponding IOCB bit set. When clear, the RBIE bit disables all
interrupt-on-changes.
Only pins configured as inputs can cause this interrupt
to occur (i.e., any RB<7:4> pin configured as an output
is excluded from the interrupt-on-change comparison).
For enabled interrupt-on-change pins, the values are
compared with the old value latched on the last read of
PORTB. The ‘mismatch’ outputs of the last read are
OR’d together to set the PORTB Change Interrupt flag
bit (RBIF) in the INTCON register.
This interrupt can wake the device from the Sleep
mode, or any of the Idle modes. The user, in the
Interrupt Service Routine, can clear the interrupt in the
following manner:
a)
b)
Any read or write of PORTB to clear the mismatch condition (except when PORTB is the
source or destination of a MOVFF instruction).
Clear the flag bit, RBIF.
A mismatch condition will continue to set the RBIF flag bit.
Reading or writing PORTB will end the mismatch
condition and allow the RBIF bit to be cleared. The latch
holding the last read value is not affected by a MCLR nor
Brown-out Reset. After either one of these Resets, the
RBIF flag will continue to be set if a mismatch is present.
Note:
WEAK PULL-UPS
Each of the PORTB pins has an individually controlled
weak internal pull-up. When set, each bit of the WPUB
register enables the corresponding pin pull-up. When
cleared, the RBPU bit of the INTCON2 register enables
pull-ups on all pins which also have their corresponding
WPUB bit set. When set, the RBPU bit disables all
weak pull-ups. The weak pull-up is automatically turned
off when the port pin is configured as an output. The
pull-ups are disabled on a Power-on Reset.
Note:
10.3.2
If a change on the I/O pin should occur
when the read operation is being executed
(start of the Q2 cycle), then the RBIF
interrupt flag may not get set. Furthermore,
since a read or write on a port affects all bits
of that port, care must be taken when using
multiple pins in Interrupt-on-change mode.
Changes on one pin may not be seen while
servicing changes on another pin.
The interrupt-on-change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt-on-change
feature. Polling of PORTB is not recommended while
using the interrupt-on-change feature.
10.3.3
ALTERNATE CCP2 OPTION
RB3 can be configured as the alternate peripheral pin
for the CCP2 module by clearing the CCP2MX Configuration bit of CONFIG3H. The default state of the
CCP2MX Configuration bit is ‘1’ which selects RC1 as
the CCP2 peripheral pin.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 10-3:
Pin
RB0/INT0/FLT0/
AN12
RB1/INT1/AN10/
C12IN3-/P1C
RB2/INT2/AN8/
P1B
RB3/AN9/C12IN2-/
CCP2
RB4/KBI0/AN11/
P1D
RB5/KBI1/PGM
Legend:
Note 1:
2:
3:
PORTB I/O SUMMARY
Function
TRIS
Setting
I/O
I/O
Type
RB0
0
O
DIG
LATB<0> data output; not affected by analog input.
1
I
TTL
PORTB<0> data input; Programmable weak pull-up. Disabled when
analog input enabled.(1)
INT0
1
I
ST
External interrupt 0 input.
Description
FLT0
1
I
ST
AN12
1
I
ANA
A/D input channel 12.(1)
Enhanced PWM Fault input (ECCP1 module); enabled by software.
RB1
0
O
DIG
LATB<1> data output; not affected by analog input.
1
I
TTL
PORTB<1> data input; Programmable weak pull-up. Disabled when
analog input enabled.(1)
INT1
1
I
ST
External Interrupt 1 input.
AN10
1
I
ANA
ADC input channel 10.(1)
C12IN3-
1
I
ANA
Comparators C1 and C2 inverting input, channel 3. Analog select is
shared with ADC.
P1C
0
O
DIG
ECCP PWM output (28-pin devices only).
RB2
0
O
DIG
LATB<2> data output; not affected by analog input.
1
I
TTL
PORTB<2> data input; Programmable weak pull-up. Disabled when
analog input enabled.(1)
INT2
1
I
ST
AN8
1
I
ANA
External interrupt 2 input.
ADC input channel 8.(1)
P1B
0
O
DIG
ECCP PWM output (28-pin devices only).
RB3
0
O
DIG
LATB<3> data output; not affected by analog input.
1
I
TTL
PORTB<3> data input; Programmable weak pull-up. Disabled when
analog input enabled.(1)
AN9
1
I
ANA
ADC input channel 9.(1)
C12IN2-
1
I
ANA
Comparators C1 and C2 inverting input, channel 2. Analog select is
shared with ADC.
CCP2(2)
0
O
DIG
CCP2 compare and PWM output.
1
I
ST
CCP2 capture input
0
O
DIG
LATB<4> data output; not affected by analog input.
1
I
TTL
PORTB<4> data input; Programmable weak pull-up. Disabled when
analog input enabled.(1)
RB4
KBI0
1
I
TTL
Interrupt-on-pin change.
AN11
1
I
ANA
ADC input channel 11.(1)
P1D
0
O
DIG
ECCP PWM output (28-pin devices only).
RB5
0
O
DIG
LATB<5> data output.
1
I
TTL
PORTB<5> data input; Programmable weak pull-up.
KBI1
1
I
TTL
Interrupt-on-pin change.
PGM
x
I
ST
Single-Supply Programming mode entry (ICSP™). Enabled by LVP
Configuration bit; all other pin functions disabled.
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x = Don’t care (TRIS bit does not affect port direction or is overridden for this option).
Configuration on POR is determined by the PBADEN Configuration bit. Pins are configured as analog inputs by default
when PBADEN is set and digital inputs when PBADEN is cleared.
Alternate assignment for CCP2 when the CCP2MX Configuration bit is ‘0’. Default assignment is RC1.
All other pin functions are disabled when ICSP or ICD are enabled.
 2010 Microchip Technology Inc.
DS41303G-page 125
PIC18F2XK20/4XK20
TABLE 10-3:
PORTB I/O SUMMARY (CONTINUED)
Pin
Function
TRIS
Setting
I/O
I/O
Type
RB6
0
O
DIG
LATB<6> data output.
RB6/KBI2/PGC
1
I
TTL
PORTB<6> data input; Programmable weak pull-up.
KBI2
1
I
TTL
Interrupt-on-pin change.
PGC
x
I
ST
Serial execution (ICSP) clock input for ICSP and ICD operation.(3)
RB7
0
O
DIG
LATB<7> data output.
1
I
TTL
PORTB<7> data input; Programmable weak pull-up.
KBI3
1
I
TTL
Interrupt-on-pin change.
PGD
x
O
DIG
Serial execution data output for ICSP and ICD operation.(3)
x
I
ST
Serial execution data input for ICSP and ICD operation.(3)
RB7/KBI3/PGD
Legend:
Note 1:
2:
3:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x = Don’t care (TRIS bit does not affect port direction or is overridden for this option).
Configuration on POR is determined by the PBADEN Configuration bit. Pins are configured as analog inputs by default
when PBADEN is set and digital inputs when PBADEN is cleared.
Alternate assignment for CCP2 when the CCP2MX Configuration bit is ‘0’. Default assignment is RC1.
All other pin functions are disabled when ICSP or ICD are enabled.
TABLE 10-4:
Name
PORTB
Description
SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RB7
RB6
RB5
RB4
RB3
RB2
RB1
RB0
LATB
PORTB Data Latch Register (Read and Write to Data Latch)
TRISB
PORTB Data Direction Control Register
Reset
Values
on page
62
62
62
WPUB
WPUB7
WPUB6
WPUB5
WPUB4
WPUB3
WPUB2
WPUB1
WPUB0
62
IOCB
IOCB7
IOCB6
IOCB5
IOCB4
—
—
—
—
62
—
SLRE(1)
SLRD(1)
SLRC
SLRB
SLRA
63
TMR0IE
INT0IE
SLRCON
INTCON
—
—
GIE/GIEH PEIE/GIEL
INTCON2
RBPU
INTCON3
INT2IP
ANSELH
—
RBIE
TMR0IF
INT0IF
RBIF
59
INTEDG0 INTEDG1 INTEDG2
—
TMR0IP
—
RBIP
59
INT1IP
—
INT2IE
INT1IE
—
INT2IF
INT1IF
59
—
—
ANS12
ANS11
ANS10
ANS9
ANS8
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTB.
Note 1: Not implemented on PIC18F2XK20 devices.
DS41303G-page 126
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
10.4
PORTC, TRISC and LATC
Registers
PORTC is an 8-bit wide, bidirectional port. The corresponding data direction register is TRISC. Setting a
TRISC bit (= 1) will make the corresponding PORTC
pin an input (i.e., disable the output driver). Clearing a
TRISC bit (= 0) will make the corresponding PORTC
pin an output (i.e., enable the output driver and put the
contents of the output latch on the selected pin).
The Data Latch register (LATC) is also memory
mapped. Read-modify-write operations on the LATC
register read and write the latched output value for
PORTC.
EXAMPLE 10-3:
CLRF
PORTC
CLRF
LATC
MOVLW
0CFh
MOVWF
TRISC
INITIALIZING PORTC
;
;
;
;
;
;
;
;
;
;
;
;
Initialize PORTC by
clearing output
data latches
Alternate method
to clear output
data latches
Value used to
initialize data
direction
Set RC<3:0> as inputs
RC<5:4> as outputs
RC<7:6> as inputs
PORTC is multiplexed with several peripheral functions
(Table 10-5). The pins have Schmitt Trigger input buffers. RC1 is the default configuration for the CCP2
peripheral pin. The CCP2 function can be relocated to
the RB3 pin by clearing the CCP2MX bit of Configuration Word CONFIG3H. The default state of the
CCP2MX Configuration bit is ‘1’.
When enabling peripheral functions, care should be
taken in defining TRIS bits for each PORTC pin. The
EUSART and MSSP peripherals override the TRIS bit
to make a pin an output or an input, depending on the
peripheral configuration. Refer to the corresponding
peripheral section for additional information.
Note:
On a Power-on Reset, these pins are configured as digital inputs.
The contents of the TRISC register are affected by
peripheral overrides. Reading TRISC always returns
the current contents, even though a peripheral device
may be overriding one or more of the pins.
 2010 Microchip Technology Inc.
DS41303G-page 127
PIC18F2XK20/4XK20
TABLE 10-5:
Pin
PORTC I/O SUMMARY
Function
TRIS
Setting
I/O
I/O
Type
RC0
0
O
DIG
RC0/T1OSO/
T13CKI
RC1/T1OSI/CCP2
RC2/CCP1/P1A
1
I
ST
x
O
ANA
T13CKI
1
I
ST
Timer1/Timer3 counter input.
RC1
0
O
DIG
LATC<1> data output.
1
I
ST
T1OSI
x
I
ANA
Timer1 oscillator input; enabled when Timer1 oscillator enabled.
Disables digital I/O.
CCP2(1)
0
O
DIG
CCP2 compare and PWM output; takes priority over port data.
1
I
ST
CCP2 capture input.
0
O
DIG
LATC<2> data output.
1
I
ST
PORTC<2> data input.
0
O
DIG
ECCP1 compare or PWM output; takes priority over port data.
1
I
ST
ECCP1 capture input.
P1A
0
O
DIG
ECCP1 Enhanced PWM output, channel A. May be configured for
tri-state during Enhanced PWM shutdown events. Takes priority over
port data.
RC3
0
O
DIG
LATC<3> data output.
1
I
ST
PORTC<3> data input.
0
O
DIG
SPI clock output (MSSP module); takes priority over port data.
RC2
SCK
SCL
RC4/SDI/SDA
RC5/SDO
RC7/RX/DT
Legend:
Note 1:
RC4
PORTC<0> data input.
Timer1 oscillator output; enabled when Timer1 oscillator enabled.
Disables digital I/O.
PORTC<1> data input.
1
I
ST
SPI clock input (MSSP module).
0
O
DIG
I2C™ clock output (MSSP module); takes priority over port data.
2
I C/SMB I2C clock input (MSSP module); input type depends on module setting.
1
I
0
O
DIG
LATC<4> data output.
1
I
ST
PORTC<4> data input.
SDI
1
I
ST
SPI data input (MSSP module).
SDA
1
O
DIG
I2C data output (MSSP module); takes priority over port data.
1
I
0
O
DIG
1
I
ST
PORTC<5> data input.
SDO
0
O
DIG
SPI data output (MSSP module); takes priority over port data.
RC6
0
O
DIG
LATC<6> data output.
RC5
RC6/TX/CK
LATC<0> data output.
T1OSO
CCP1
RC3/SCK/SCL
Description
I2C/SMB I2C data input (MSSP module); input type depends on module setting.
LATC<5> data output.
1
I
ST
PORTC<6> data input.
TX
1
O
DIG
Asynchronous serial transmit data output (USART module); takes
priority over port data. User must configure as output.
CK
1
O
DIG
Synchronous serial clock output (USART module); takes priority over
port data.
1
I
ST
Synchronous serial clock input (USART module).
0
O
DIG
LATC<7> data output.
1
I
ST
PORTC<7> data input.
RX
1
I
ST
Asynchronous serial receive data input (USART module).
DT
1
O
DIG
Synchronous serial data output (USART module); takes priority over
port data.
1
I
ST
Synchronous serial data input (USART module). User must configure
as an input.
RC7
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
I2C/SMB = I2C/SMBus input buffer; x = Don’t care (TRIS bit does not affect port direction or is overridden for this option).
Default assignment for CCP2 when the CCP2MX Configuration bit is set. Alternate assignment is RB3.
DS41303G-page 128
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 10-6:
Name
PORTC
SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
LATC
PORTC Data Latch Register (Read and Write to Data Latch)
TRISC
PORTC Data Direction Control Register
T1RUN
T3CON
RD16
T3CCP2 T3CKPS1 T3CKPS0 T3CCP1
TXSTA
CSRC
TX9
62
62
62
RD16
T1CON
Reset
Values
on page
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
TXEN
SYNC
SENDB
T3SYNC
BRGH
TMR1CS TMR1ON
TMR3CS TMR3ON
TRMT
60
61
TX9D
61
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
61
SSPCON1
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
60
CCP1CON
P1M1
P1M0
DC1B1
DC1B0
CCP1M3 CCP1M2 CCP1M1 CCP1M0
61
CCP2CON
—
—
DC2B1
DC2B0
CCP2M3 CCP2M2 CCP2M1 CCP2M0
61
ECCP1AS
SLRCON
ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1
—
—
—
SLRE(1)
SLRD(1)
PSSAC0
PSSBD1
PSSBD0
61
SLRC
SLRB
SLRA
63
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTC.
Note 1: Not implemented on PIC18F2XK20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 129
PIC18F2XK20/4XK20
10.5
Note:
PORTD, TRISD and LATD
Registers
PORTD is only available on 40/44-pin
devices.
PORTD is an 8-bit wide, bidirectional port. The corresponding data direction register is TRISD. Setting a
TRISD bit (= 1) will make the corresponding PORTD
pin an input (i.e., disable the output driver). Clearing a
TRISD bit (= 0) will make the corresponding PORTD
pin an output (i.e., enable the output driver and put the
contents of the output latch on the selected pin).
The Data Latch register (LATD) is also memory
mapped. Read-modify-write operations on the LATD
register read and write the latched output value for
PORTD.
All pins on PORTD are implemented with Schmitt Trigger input buffers. Each pin is individually configurable
as an input or output.
Three of the PORTD pins are multiplexed with outputs
P1B, P1C and P1D of the enhanced CCP module. The
operation of these additional PWM output pins is
covered in greater detail in Section 16.0 “Enhanced
Capture/Compare/PWM (ECCP) Module”.
Note:
PORTD can also be configured as an 8-bit wide microprocessor port (Parallel Slave Port) by setting control
bit, PSPMODE (TRISE<4>). In this mode, the input
buffers are TTL. See Section 10.9 “Parallel Slave
Port” for additional information on the Parallel Slave
Port (PSP).
Note:
When the enhanced PWM mode is used
with either dual or quad outputs, the PSP
functions of PORTD are automatically
disabled.
EXAMPLE 10-4:
CLRF
PORTD
CLRF
LATD
MOVLW
0CFh
MOVWF
TRISD
INITIALIZING PORTD
;
;
;
;
;
;
;
;
;
;
;
;
Initialize PORTD by
clearing output
data latches
Alternate method
to clear output
data latches
Value used to
initialize data
direction
Set RD<3:0> as inputs
RD<5:4> as outputs
RD<7:6> as inputs
On a Power-on Reset, these pins are
configured as digital inputs.
DS41303G-page 130
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 10-7:
Pin
RD0/PSP0
RD1/PSP1
RD2/PSP2
RD3/PSP3
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
PORTD I/O SUMMARY
Function
TRIS
Setting
I/O
I/O
Type
RD0
0
O
DIG
1
I
ST
PORTD<0> data input.
PSP0
x
O
DIG
PSP read data output (LATD<0>); takes priority over port data.
Legend:
LATD<0> data output.
x
I
TTL
PSP write data input.
RD1
0
O
DIG
LATD<1> data output.
1
I
ST
PORTD<1> data input.
PSP1
x
O
DIG
PSP read data output (LATD<1>); takes priority over port data.
x
I
TTL
PSP write data input.
RD2
0
O
DIG
LATD<2> data output.
1
I
ST
PORTD<2> data input.
PSP2
x
O
DIG
PSP read data output (LATD<2>); takes priority over port data.
x
I
TTL
PSP write data input.
RD3
0
O
DIG
LATD<3> data output.
1
I
ST
PORTD<3> data input.
PSP3
x
O
DIG
PSP read data output (LATD<3>); takes priority over port data.
x
I
TTL
PSP write data input.
RD4
0
O
DIG
LATD<4> data output.
1
I
ST
PORTD<4> data input.
PSP4
x
O
DIG
PSP read data output (LATD<4>); takes priority over port data.
x
I
TTL
PSP write data input.
RD5
0
O
DIG
LATD<5> data output.
1
I
ST
PORTD<5> data input.
PSP5
x
O
DIG
PSP read data output (LATD<5>); takes priority over port data.
x
I
TTL
PSP write data input.
P1B
0
O
DIG
ECCP1 Enhanced PWM output, channel B; takes priority over port and
PSP data. May be configured for tri-state during Enhanced PWM
shutdown events.
RD6
0
O
DIG
LATD<6> data output.
1
I
ST
PORTD<6> data input.
x
O
DIG
PSP read data output (LATD<6>); takes priority over port data.
x
I
TTL
PSP write data input.
P1C
0
O
DIG
ECCP1 Enhanced PWM output, channel C; takes priority over port and
PSP data. May be configured for tri-state during Enhanced PWM
shutdown events.
RD7
0
O
DIG
LATD<7> data output.
1
I
ST
PORTD<7> data input.
PSP7
x
O
DIG
PSP read data output (LATD<7>); takes priority over port data.
x
I
TTL
PSP write data input.
P1D
0
O
DIG
ECCP1 Enhanced PWM output, channel D; takes priority over port and
PSP data. May be configured for tri-state during Enhanced PWM
shutdown events.
PSP6
RD7/PSP7/P1D
Description
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; x = Don’t care
(TRIS bit does not affect port direction or is overridden for this option).
 2010 Microchip Technology Inc.
DS41303G-page 131
PIC18F2XK20/4XK20
TABLE 10-8:
Name
PORTD(1)
SUMMARY OF REGISTERS ASSOCIATED WITH PORTD
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
LATD(1)
PORTD Data Latch Register (Read and Write to Data Latch)
TRISD(1)
PORTD Data Direction Control Register
TRISE(1)
IBF
OBF
IBOV
CCP1CON
P1M1
P1M0
SLRCON
—
—
Reset
Values
on page
62
62
62
PSPMODE
—
TRISE2
TRISE1
TRISE0
62
DC1B1
DC1B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0
61
—
SLRE(1)
SLRD(1)
SLRC
SLRB
SLRA
63
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTD.
Note 1: Not implemented on PIC18F2XK20 devices.
DS41303G-page 132
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
10.6
PORTE, TRISE and LATE
Registers
Depending on the particular PIC18F2XK20/4XK20
device selected, PORTE is implemented in two
different ways.
10.6.1
PORTE IN PIC18F4XK20 DEVICES
For PIC18F4XK20 devices, PORTE is a 4-bit wide port.
Three pins (RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/
AN7) are individually configurable as inputs or outputs.
These pins have Schmitt Trigger input buffers. When
selected as an analog input, these pins will read as ‘0’s.
The corresponding data direction register is TRISE.
Setting a TRISE bit (= 1) will make the corresponding
PORTE pin an input (i.e., disable the output driver).
Clearing a TRISE bit (= 0) will make the corresponding
PORTE pin an output (i.e., enable the output driver and
put the contents of the output latch on the selected pin).
TRISE controls the direction of the RE pins, even when
they are being used as analog inputs. The user must
make sure to keep the pins configured as inputs when
using them as analog inputs.
Note:
On a Power-on Reset, RE<2:0> are
configured as analog inputs.
The upper four bits of the TRISE register also control
the operation of the Parallel Slave Port. Their operation
is explained in Register 10-1.
The Data Latch register (LATE) is also memory
mapped. Read-modify-write operations on the LATE
register, read and write the latched output value for
PORTE.
 2010 Microchip Technology Inc.
The fourth pin of PORTE (MCLR/VPP/RE3) is an input
only pin. Its operation is controlled by the MCLRE
Configuration bit. When selected as a port pin
(MCLRE = 0), it functions as a digital input only pin; as
such, it does not have TRIS or LAT bits associated with its
operation. Otherwise, it functions as the device’s Master
Clear input. In either configuration, RE3 also functions as
the programming voltage input during programming.
Note:
On a Power-on Reset, RE3 is enabled as
a digital input only if Master Clear
functionality is disabled.
EXAMPLE 10-5:
CLRF
CLRF
MOVLW
ANDWF
MOVLW
MOVWF
10.6.2
PORTE
;
;
;
LATE
;
;
;
1Fh
;
ANSEL,w ;
05h
;
;
;
TRISE
;
;
;
INITIALIZING PORTE
Initialize PORTE by
clearing output
data latches
Alternate method
to clear output
data latches
Configure analog pins
for digital only
Value used to
initialize data
direction
Set RE<0> as input
RE<1> as output
RE<2> as input
PORTE IN PIC18F2XK20 DEVICES
For PIC18F2XK20 devices, PORTE is only available
when Master Clear functionality is disabled
(MCLR = 0). In these cases, PORTE is a single bit,
input only port comprised of RE3 only. The pin operates
as previously described.
DS41303G-page 133
PIC18F2XK20/4XK20
REGISTER 10-1:
TRISE: PORTE/PSP CONTROL REGISTER (PIC18F4XK20 DEVICES ONLY)
R-0
R-0
R/W-0
R/W-0
U-0
R/W-1
R/W-1
R/W-1
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
IBF: Input Buffer Full Status bit
1 = A word has been received and waiting to be read by the CPU
0 = No word has been received
bit 6
OBF: Output Buffer Full Status bit
1 = The output buffer still holds a previously written word
0 = The output buffer has been read
bit 5
IBOV: Input Buffer Overflow Detect bit (in Microprocessor mode)
1 = A write occurred when a previously input word has not been read (must be cleared by software)
0 = No overflow occurred
bit 4
PSPMODE: Parallel Slave Port Mode Select bit
1 = Parallel Slave Port mode
0 = General purpose I/O mode
bit 3
Unimplemented: Read as ‘0’
bit 2
TRISE2: RE2 Direction Control bit
1 = Input
0 = Output
bit 1
TRISE1: RE1 Direction Control bit
1 = Input
0 = Output
bit 0
TRISE0: RE0 Direction Control bit
1 = Input
0 = Output
DS41303G-page 134
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 10-9:
Pin
PORTE I/O SUMMARY
Function
TRIS
Setting
I/O
I/O
Type
RE0
0
O
DIG
LATE<0> data output; not affected by analog input.
1
I
ST
PORTE<0> data input; disabled when analog input enabled.
RE0/RD/AN5
RE1/WR/AN6
RE2/CS/AN7
MCLR/VPP/
RE3(1,2)
Legend:
Note 1:
2:
Description
RD
1
I
TTL
PSP read enable input (PSP enabled).
AN5
1
I
ANA
A/D input channel 5; default input configuration on POR.
RE1
0
O
DIG
LATE<1> data output; not affected by analog input.
1
I
ST
PORTE<1> data input; disabled when analog input enabled.
WR
1
I
TTL
PSP write enable input (PSP enabled).
AN6
1
I
ANA
A/D input channel 6; default input configuration on POR.
RE2
0
O
DIG
LATE<2> data output; not affected by analog input.
1
I
ST
PORTE<2> data input; disabled when analog input enabled.
CS
1
I
TTL
PSP write enable input (PSP enabled).
AN7
1
I
ANA
A/D input channel 7; default input configuration on POR.
MCLR
—
I
ST
External Master Clear input; enabled when MCLRE Configuration bit is
set.
VPP
—
I
ANA
High-voltage detection; used for ICSP™ mode entry detection. Always
available, regardless of pin mode.
RE3
—(2)
I
ST
PORTE<3> data input; enabled when MCLRE Configuration bit is
clear.
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x = Don’t care (TRIS bit does not affect port direction or is overridden for this option).
RE3 is available on both PIC18F2XK20 and PIC18F4XK20 devices. All other PORTE pins are only implemented on
PIC18F4XK20 devices.
RE3 does not have a corresponding TRIS bit to control data direction.
TABLE 10-10: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE
Name
Bit 6
Bit 5
Bit 4
Bit 3
PORTE
—
—
—
—
RE3(1,2)
LATE(2)
—
—
—
—
—
TRISE(3)
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
62
SLRCON
—
—
—
SLRE(3)
SLRD(3)
SLRC
SLRB
SLRA
63
ANS4
ANS3
ANS2
ANS1
ANS0
62
ANSEL
ANS7(3)
(3)
ANS6
ANS5
(3)
Bit 2
Bit 1
Bit 0
RE2
RE1
RE0
Reset
Values
on page
Bit 7
LATE Data Output Register
62
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTE.
Note 1: Implemented only when Master Clear functionality is disabled (MCLRE Configuration bit = 0).
2: RE3 is the only PORTE bit implemented on both PIC18F2XK20 and PIC18F4XK20 devices. All other bits
are implemented only when PORTE is implemented (i.e., PIC18F4XK20 devices).
3: Unimplemented on PIC18F2XK20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 135
PIC18F2XK20/4XK20
10.7
Port Analog Control
Some port pins are multiplexed with analog functions
such as the Analog-to-Digital Converter and comparators. When these I/O pins are to be used as analog
inputs it is necessary to disable the digital input buffer
to avoid excessive current caused by improper biasing
of the digital input. Individual control of the digital input
buffers on pins which share analog functions is provided by the ANSEL and ANSELH registers. Setting an
ANSx bit high will disable the associated digital input
REGISTER 10-2:
buffer and cause all reads of that pin to return ‘0’ while
allowing analog functions of that pin to operate
correctly.
The state of the ANSx bits has no affect on digital
output functions. A pin with the associated TRISx bit
clear and ANSx bit set will still operate as a digital
output but the input mode will be analog. This can
cause unexpected behavior when performing readmodify-write operations on the affected port.
ANSEL: ANALOG SELECT REGISTER 1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
ANS7(1)
ANS6(1)
ANS5(1)
ANS4
ANS3
ANS2
ANS1
ANS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
ANS7: RE2 Analog Select Control bit(1)
1 = Digital input buffer of RE2 is disabled
0 = Digital input buffer of RE2 is enabled
bit 6
ANS6: RE1 Analog Select Control bit(1)
1 = Digital input buffer of RE1 is disabled
0 = Digital input buffer of RE1 is enabled
bit 5
ANS5: RE0 Analog Select Control bit(1)
1 = Digital input buffer of RE0 is disabled
0 = Digital input buffer of RE0 is enabled
bit 4
ANS4: RA5 Analog Select Control bit
1 = Digital input buffer of RA5 is disabled
0 = Digital input buffer of RA5 is enabled
bit 3
ANS3: RA3 Analog Select Control bit
1 = Digital input buffer of RA3 is disabled
0 = Digital input buffer of RA3 is enabled
bit 2
ANS2: RA2 Analog Select Control bit
1 = Digital input buffer of RA2 is disabled
0 = Digital input buffer of RA2 is enabled
bit 1
ANS1: RA1 Analog Select Control bit
1 = Digital input buffer of RA1 is disabled
0 = Digital input buffer of RA1 is enabled
bit 0
ANS0: RA0 Analog Select Control bit
1 = Digital input buffer of RA0 is disabled
0 = Digital input buffer of RA0 is enabled
Note 1:
x = Bit is unknown
These bits are not implemented on PIC18F2XK20 devices.
DS41303G-page 136
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 10-3:
ANSELH: ANALOG SELECT REGISTER 2
U-0
U-0
U-0
R/W-1(1)
R/W-1(1)
R/W-1(1)
R/W-1(1)
R/W-1(1)
—
—
—
ANS12
ANS11
ANS10
ANS9
ANS8
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-5
Unimplemented: Read as ‘0’
bit 4
ANS12: RB0 Analog Select Control bit
1 = Digital input buffer of RB0 is disabled
0 = Digital input buffer of RB0 is enabled
bit 3
ANS11: RB4 Analog Select Control bit
1 = Digital input buffer of RB4 is disabled
0 = Digital input buffer of RB4 is enabled
bit 2
ANS10: RB1 Analog Select Control bit
1 = Digital input buffer of RB1 is disabled
0 = Digital input buffer of RB1 is enabled
bit 1
ANS9: RB3 Analog Select Control bit
1 = Digital input buffer of RB3 is disabled
0 = Digital input buffer of RB3 is enabled
bit 0
ANS8: RB2 Analog Select Control bit
1 = Digital input buffer of RB2 is disabled
0 = Digital input buffer of RB2 is enabled
Note 1:
x = Bit is unknown
Default state is determined by the PBADEN bit of CONFIG3H. The default state is ‘0’ When
PBADEN = ‘0’.
 2010 Microchip Technology Inc.
DS41303G-page 137
PIC18F2XK20/4XK20
10.8
Port Slew Rate Control
The output slew rate of each port is programmable to
select either the standard transition rate or a reduced
transition rate of 0.1 times the standard to minimize
EMI. The reduced transition time is the default slew
rate for all ports.
REGISTER 10-4:
SLRCON: SLEW RATE CONTROL REGISTER
U-0
U-0
U-0
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
—
—
—
SLRE(1)
SLRD(1)
SLRC
SLRB
SLRA
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-5
Unimplemented: Read as ‘0’
bit 4
SLRE: PORTE Slew Rate Control bit(1)
1 = All outputs on PORTE slew at a limited rate
0 = All outputs on PORTE slew at the standard rate
bit 3
SLRD: PORTD Slew Rate Control bit(1)
1 = All outputs on PORTD slew at a limited rate
0 = All outputs on PORTD slew at the standard rate
bit 2
SLRC: PORTC Slew Rate Control bit
1 = All outputs on PORTC slew at a limited rate
0 = All outputs on PORTC slew at the standard rate
bit 1
SLRB: PORTB Slew Rate Control bit
1 = All outputs on PORTB slew at a limited rate
0 = All outputs on PORTB slew at the standard rate
bit 0
SLRA: PORTA Slew Rate Control bit
1 = All outputs on PORTA slew at a limited rate(2)
0 = All outputs on PORTA slew at the standard rate
Note 1:
2:
x = Bit is unknown
These bits are not implemented on PIC18F2XK20 devices.
The slew rate of RA6 defaults to standard rate when the pin is used as CLKOUT.
DS41303G-page 138
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
10.9
Note:
Parallel Slave Port
The Parallel Slave Port is only available on
PIC18F4XK20 devices.
In addition to its function as a general I/O port, PORTD
can also operate as an 8-bit wide Parallel Slave Port
(PSP) or microprocessor port. PSP operation is
controlled by the 4 upper bits of the TRISE register
(Register 10-1). Setting control bit, PSPMODE
(TRISE<4>), enables PSP operation as long as the
enhanced CCP module is not operating in dual output
or quad output PWM mode. In Slave mode, the port is
asynchronously readable and writable by the external
world.
The PSP can directly interface to an 8-bit
microprocessor data bus. The external microprocessor
can read or write the PORTD latch as an 8-bit latch.
Setting the control bit, PSPMODE, enables the PORTE
I/O pins to become control inputs for the microprocessor
port. When set, port pin RE0 is the RD input, RE1 is the
WR input and RE2 is the CS (Chip Select) input. For this
functionality, the corresponding data direction bits of the
TRISE register (TRISE<2:0>) must be configured as
inputs (set) and the ANSEL<7:5> bits must be cleared.
A write to the PSP occurs when both the CS and WR
lines are first detected low and ends when either are
detected high. The PSPIF and IBF flag bits are both set
when the write ends.
The timing for the control signals in Write and Read
modes is shown in Figure 10-3 and Figure 10-4,
respectively.
FIGURE 10-2:
One bit of PORTD
Data Bus
D
WR LATD
or
WR PORTD
 2010 Microchip Technology Inc.
Q
RDx pin
CK
Data Latch
Q
RD PORTD
TTL
D
ENEN
RD LATD
Set Interrupt Flag
PSPIF (PIR1<7>)
PORTE Pins
Read
A read from the PSP occurs when both the CS and RD
lines are first detected low. The data in PORTD is read
out and the OBF bit is clear. If the user writes new data
to PORTD to set OBF, the data is immediately read out;
however, the OBF bit is not set.
When either the CS or RD lines are detected high, the
PORTD pins return to the input state and the PSPIF bit
is set. User applications should wait for PSPIF to be set
before servicing the PSP; when this happens, the IBF
and OBF bits can be polled and the appropriate action
taken.
PORTD AND PORTE
BLOCK DIAGRAM
(PARALLEL SLAVE PORT)
TTL
RD
Chip Select
TTL
CS
Write
TTL
Note:
WR
I/O pins have diode protection to VDD and VSS.
DS41303G-page 139
PIC18F2XK20/4XK20
FIGURE 10-3:
PARALLEL SLAVE PORT WRITE WAVEFORMS
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q4
Q1
Q2
Q3
Q4
CS
WR
RD
PORTD<7:0>
IBF
OBF
PSPIF
FIGURE 10-4:
PARALLEL SLAVE PORT READ WAVEFORMS
Q1
Q2
Q3
Q4
Q1
Q2
Q3
CS
WR
RD
PORTD<7:0>
IBF
OBF
PSPIF
DS41303G-page 140
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 10-11: REGISTERS ASSOCIATED WITH PARALLEL SLAVE PORT
Name
PORTD(1)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
LATD(1)
PORTD Data Latch Register (Read and Write to Data Latch)
TRISD(1)
PORTD Data Direction Control Register
PORTE
—
—
—
Reset
Values
on page
62
62
62
—
RE3
RE2(1)
RE1(1)
RE0(1)
62
TRISE1
TRISE0
62
LATE(1)
—
—
—
—
—
TRISE(1)
IBF
OBF
IBOV
PSPMODE
—
SLRCON
—
—
—
SLRE(1)
SLRD(1)
SLRC
SLRB
SLRA
63
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
INTCON
GIE/GIEH PEIE/GIEL
LATE Data Output bits
TRISE2
62
PIR1
(1)
PSPIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
ANSEL
ANS7(1)
ANS6(1)
ANS5(1)
ANS4
ANS3
ANS2
ANS1
ANS0
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Parallel Slave Port.
Note 1: Unimplemented on PIC18F2XK20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 141
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 142
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
11.0
CAPTURE/COMPARE/PWM
(CCP) MODULES
The Capture and Compare operations described in this
chapter apply to both standard and enhanced CCP
modules.
PIC18F2XK20/4XK20 devices have two CCP
Capture/Compare/PWM) modules. Each module
contains a 16-bit register which can operate as a 16-bit
Capture register, a 16-bit Compare register or a PWM
Master/Slave Duty Cycle register.
CCP1 is implemented as an enhanced CCP module with
standard Capture and Compare modes and enhanced
PWM modes. The ECCP implementation is discussed in
Section 16.0 “Enhanced Capture/Compare/PWM
(ECCP) Module”. CCP2 is implemented as a standard
CCP module without the enhanced features.
REGISTER 11-1:
Note: Throughout this section and Section 16.0
“Enhanced Capture/Compare/PWM (ECCP)
Module”, references to the register and bit
names for CCP modules are referred to
generically by the use of ‘x’ or ‘y’ in place of the
specific module number. Thus, “CCPxCON”
might refer to the control register for CCP1,
CCP2 or ECCP1. “CCPxCON” is used
throughout these sections to refer to the
module control register, regardless of whether
the CCP module is a standard or enhanced
implementation.
CCP2CON: STANDARD CAPTURE/COMPARE/PWM CONTROL REGISTER
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
DC2B1
DC2B0
CCP2M3
CCP2M2
CCP2M1
CCP2M0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
Unimplemented: Read as ‘0’
bit 5-4
DC2B<1:0>: PWM Duty Cycle bit 1 and bit 0 for CCP2 Module
Capture mode:
Unused.
Compare mode:
Unused.
PWM mode:
These bits are the two LSbs (bit 1 and bit 0) of the 10-bit PWM duty cycle. The eight MSbs
(DC2B<9:2>) of the duty cycle are found in CCPR2L.
bit 3-0
CCP2M<3:0>: CCP2 Mode Select bits
0000 = Capture/Compare/PWM disabled (resets CCP2 module)
0001 = Reserved
0010 = Compare mode, toggle output on match (CCP2IF bit is set)
0011 = Reserved
0100 = Capture mode, every falling edge
0101 = Capture mode, every rising edge
0110 = Capture mode, every 4th rising edge
0111 = Capture mode, every 16th rising edge
1000 = Compare mode: initialize CCP2 pin low; on compare match, force CCP2 pin high
(CCP2IF bit is set)
1001 = Compare mode: initialize CCP2 pin high; on compare match, force CCP2 pin low
(CCP2IF bit is set)
1010 = Compare mode: generate software interrupt on compare match (CCP2IF bit is set,
CCP2 pin reflects I/O state)
1011 = Compare mode: trigger special event, reset timer, start A/D conversion on
CCP2 match (CCP2IF bit is set)
11xx = PWM mode
 2010 Microchip Technology Inc.
DS41303G-page 143
PIC18F2XK20/4XK20
11.1
CCP Module Configuration
Each Capture/Compare/PWM module is associated
with a control register (generically, CCPxCON) and a
data register (CCPRx). The data register, in turn, is
comprised of two 8-bit registers: CCPRxL (low byte)
and CCPRxH (high byte). All registers are both
readable and writable.
11.1.1
CCP MODULES AND TIMER
RESOURCES
The CCP modules utilize Timers 1, 2 or 3, depending
on the mode selected. Timer1 and Timer3 are available
to modules in Capture or Compare modes, while
Timer2 is available for modules in PWM mode.
TABLE 11-1:
CCP MODE – TIMER
RESOURCE
CCP/ECCP Mode
Timer Resource
Capture
Timer1 or Timer3
Compare
Timer1 or Timer3
PWM
Timer2
TABLE 11-2:
The assignment of a particular timer to a module is
determined by the Timer-to-CCP enable bits in the
T3CON register (Register 15-1). Both modules can be
active at the same time and can share the same timer
resource if they are configured to operate in the same
mode (Capture/Compare or PWM). The interactions
between the two modules are summarized in Figure 11-1
and Figure 11-2. In Asynchronous Counter mode, the
capture operation will not work reliably.
11.1.2
CCP2 PIN ASSIGNMENT
The pin assignment for CCP2 (Capture input, Compare
and PWM output) can change, based on device configuration. The CCP2MX Configuration bit determines the
pin with which CCP2 is multiplexed. By default, it is
assigned to RC1 (CCP2MX = 1). If the Configuration bit
is cleared, CCP2 is multiplexed with RB3.
Changing the pin assignment of CCP2 does not
automatically change any requirements for configuring
the port pin. Users must always verify that the
appropriate TRIS register is configured correctly for
CCP2 operation, regardless of where it is located.
INTERACTIONS BETWEEN CCP1 AND CCP2 FOR TIMER RESOURCES
CCP1 Mode CCP2 Mode
Interaction
Capture
Capture
Each module can use TMR1 or TMR3 as the time base. The time base can be different
for each CCP.
Capture
Compare
CCP2 can be configured for the Special Event Trigger to reset TMR1 or TMR3
(depending upon which time base is used). Automatic A/D conversions on trigger event
can also be done. Operation of CCP1 could be affected if it is using the same timer as a
time base.
Compare
Capture
CCP1 can be configured for the Special Event Trigger to reset TMR1 or TMR3
(depending upon which time base is used). Operation of CCP2 could be affected if it is
using the same timer as a time base.
Compare
Compare
Either module can be configured for the Special Event Trigger to reset the time base.
Automatic A/D conversions on CCP2 trigger event can be done. Conflicts may occur if
both modules are using the same time base.
Capture
PWM
None
Compare
PWM
None
PWM(1)
Capture
None
PWM(1)
Compare
None
(1)
PWM
Note 1:
PWM
Both PWMs will have the same frequency and update rate (TMR2 interrupt).
Includes standard and enhanced PWM operation.
DS41303G-page 144
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
11.2
Capture Mode
In Capture mode, the CCPRxH:CCPRxL register pair
captures the 16-bit value of the TMR1 or TMR3
registers when an event occurs on the corresponding
CCPx pin. An event is defined as one of the following:
•
•
•
•
every falling edge
every rising edge
every 4th rising edge
every 16th rising edge
EXAMPLE 11-1:
CLRF
MOVLW
MOVWF
CHANGING BETWEEN
CAPTURE PRESCALERS
(CCP2 SHOWN)
CCP2CON
; Turn CCP module off
NEW_CAPT_PS ; Load WREG with the
; new prescaler mode
; value and CCP ON
CCP2CON
; Load CCP2CON with
; this value
The event is selected by the mode select bits,
CCPxM<3:0> of the CCPxCON register. When a capture is made, the interrupt request flag bit, CCPxIF, is
set; it must be cleared by software. If another capture
occurs before the value in register CCPRx is read, the
old captured value is overwritten by the new captured
value.
11.2.1
CCP PIN CONFIGURATION
In Capture mode, the appropriate CCPx pin should be
configured as an input by setting the corresponding
TRIS direction bit.
Note:
11.2.2
If the CCPx pin is configured as an output,
a write to the port can cause a capture
condition.
TIMER1/TIMER3 MODE SELECTION
The timers that are to be used with the capture feature
(Timer1 and/or Timer3) must be running in Timer mode
or Synchronized Counter mode. In Asynchronous Counter mode, the capture operation may not work. The timer
to be used with each CCP module is selected in the
T3CON register (see Section 11.1.1 “CCP Modules
and Timer Resources”).
11.2.3
SOFTWARE INTERRUPT
When the Capture mode is changed, a false capture
interrupt may be generated. The user should keep the
CCPxIE interrupt enable bit clear to avoid false interrupts. The interrupt flag bit, CCPxIF, should also be
cleared following any such change in operating mode.
11.2.4
CCP PRESCALER
There are four prescaler settings in Capture mode; they
are specified as part of the operating mode selected by
the mode select bits (CCPxM<3:0>). Whenever the
CCP module is turned off or Capture mode is disabled,
the prescaler counter is cleared. This means that any
Reset will clear the prescaler counter.
Switching from one capture prescaler to another may
generate an interrupt. Also, the prescaler counter will
not be cleared; therefore, the first capture may be from
a non-zero prescaler. Example 11-1 shows the
recommended method for switching between capture
prescalers. This example also clears the prescaler
counter and will not generate the “false” interrupt.
 2010 Microchip Technology Inc.
DS41303G-page 145
PIC18F2XK20/4XK20
FIGURE 11-1:
CAPTURE MODE OPERATION BLOCK DIAGRAM
TMR3H
TMR3L
Set CCP1IF
T3CCP2
CCP1 pin
Prescaler
 1, 4, 16
and
Edge Detect
CCPR1H
T3CCP2
4
CCP1CON<3:0>
Q1:Q4
CCP2CON<3:0>
4
TMR3
Enable
CCPR1L
TMR1
Enable
TMR1H
TMR1L
TMR3H
TMR3L
Set CCP2IF
4
T3CCP1
T3CCP2
TMR3
Enable
CCP2 pin
Prescaler
 1, 4, 16
and
Edge Detect
CCPR2H
CCPR2L
TMR1
Enable
T3CCP2
T3CCP1
DS41303G-page 146
TMR1H
TMR1L
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
11.3
11.3.2
Compare Mode
TIMER1/TIMER3 MODE SELECTION
In Compare mode, the 16-bit CCPRx register value is
constantly compared against either the TMR1 or TMR3
register pair value. When a match occurs, the CCPx pin
can be:
Timer1 and/or Timer3 must be running in Timer mode
or Synchronized Counter mode if the CCP module is
using the compare feature. In Asynchronous Counter
mode, the compare operation will not work reliably.
•
•
•
•
11.3.3
driven high
driven low
toggled (high-to-low or low-to-high)
remain unchanged (that is, reflects the state of the
I/O latch)
When the Generate Software Interrupt mode is chosen
(CCPxM<3:0> = 1010), the corresponding CCPx pin is
not affected. Only the CCPxIF interrupt flag is affected.
11.3.4
The action on the pin is based on the value of the mode
select bits (CCPxM<3:0>). At the same time, the interrupt flag bit, CCPxIF, is set.
11.3.1
SPECIAL EVENT TRIGGER
Both CCP modules are equipped with a Special Event
Trigger. This is an internal hardware signal generated
in Compare mode to trigger actions by other modules.
The Special Event Trigger is enabled by selecting
the Compare Special Event Trigger mode
(CCPxM<3:0> = 1011).
CCP PIN CONFIGURATION
The user must configure the CCPx pin as an output by
clearing the appropriate TRIS bit.
Note:
SOFTWARE INTERRUPT MODE
For either CCP module, the Special Event Trigger resets
the timer register pair for whichever timer resource is
currently assigned as the module’s time base. This
allows the CCPRx registers to serve as a programmable
period register for either timer.
Clearing the CCPxCON register will force
the CCPx compare output latch (depending on device configuration) to the default
low level. This is not the PORTB or
PORTC I/O data latch.
The Special Event Trigger for CCP2 can also start an
A/D conversion. In order to do this, the A/D converter
must already be enabled.
FIGURE 11-2:
COMPARE MODE OPERATION BLOCK DIAGRAM
CCPR1H
Set CCP1IF
CCPR1L
Special Event Trigger
(Timer1/Timer3 Reset)
CCP1 pin
Comparator
Output
Logic
Compare
Match
S
Q
R
TRIS
Output Enable
4
CCP1CON<3:0>
0
TMR1H
TMR1L
0
1
TMR3H
TMR3L
1
Special Event Trigger
(Timer1/Timer3 Reset, A/D Trigger)
T3CCP1
T3CCP2
Set CCP2IF
Comparator
CCPR2H
CCPR2L
Compare
Match
CCP2 pin
Output
Logic
4
S
Q
R
TRIS
Output Enable
CCP2CON<3:0>
 2010 Microchip Technology Inc.
DS41303G-page 147
PIC18F2XK20/4XK20
TABLE 11-3:
Name
INTCON
REGISTERS ASSOCIATED WITH CAPTURE, COMPARE, TIMER1 AND TIMER3
Bit 7
Bit 6
Bit 5
Reset
Values
on page
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
—
RI
TO
PD
POR
BOR
58
IPEN
SBOREN
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
(1)
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
RCON
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
TRISB
PORTB Data Direction Control Register
62
TRISC
PORTC Data Direction Control Register
62
TMR1L
Timer1 Register, Low Byte
60
TMR1H
Timer1 Register, High Byte
T1CON
RD16
T1RUN
60
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
TMR1CS TMR1ON
60
TMR3H
Timer3 Register, High Byte
61
TMR3L
Timer3 Register, Low Byte
61
T3CON
RD16
T3CCP2
T3CKPS1 T3CKPS0
T3CCP1
T3SYNC
TMR3CS TMR3ON
61
CCPR1L
Capture/Compare/PWM Register 1, Low Byte
61
CCPR1H
Capture/Compare/PWM Register 1, High Byte
61
CCP1CON
P1M1
P1M0
DC1B1
DC1B0
CCPR2L
Capture/Compare/PWM Register 2, Low Byte
CCPR2H
Capture/Compare/PWM Register 2, High Byte
CCP2CON
—
—
DC2B1
DC2B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0
61
61
61
CCP2M3
CCP2M2
CCP2M1
CCP2M0
61
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by Capture/Compare, Timer1 or Timer3.
Note 1: Not impemented on PIC18F2XK20 devices.
DS41303G-page 148
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
11.4
PWM Mode
The PWM mode generates a Pulse-Width Modulated
signal on the CCP2 pin for the CCP module and the
P1A through P1D pins for the ECCP module. Hereafter
the modulated output pin will be referred to as the CCPx
pin. The duty cycle, period and resolution are
determined by the following registers:
•
•
•
•
The PWM output (Figure 11-4) has a time base
(period) and a time that the output stays high (duty
cycle).
FIGURE 11-4:
Period
Pulse Width
PR2
T2CON
CCPRxL
CCPxCON
CCP PWM OUTPUT
TMR2 = PR2
TMR2 = CCPRxL:DCxB<1:0>
TMR2 = 0
In Pulse-Width Modulation (PWM) mode, the CCP
module produces up to a 10-bit resolution PWM output
on the CCPx pin. Since the CCPx pin is multiplexed
with the PORT data latch, the TRIS for that pin must be
cleared to enable the CCPx pin output driver.
Note:
Clearing the CCPxCON register will
relinquish CCPx control of the CCPx pin.
Figure 11.1.1 shows a simplified block diagram of
PWM operation.
Figure 11-4 shows a typical waveform of the PWM
signal.
For a step-by-step procedure on how to set up the CCP
module for PWM operation, see Section 11.4.7
“Setup for PWM Operation”.
FIGURE 11-3:
SIMPLIFIED PWM BLOCK
DIAGRAM
DCxB<1:0>
Duty Cycle Registers
CCPRxL
CCPRxH(2) (Slave)
CCPx
R
Comparator
TMR2
(1)
Q
S
TRIS
Comparator
PR2
Note 1:
2:
Clear Timer2,
toggle CCPx pin and
latch duty cycle
The 8-bit timer TMR2 register is concatenated
with the 2-bit internal system clock (FOSC), or
2 bits of the prescaler, to create the 10-bit time
base.
In PWM mode, CCPRxH is a read-only register.
 2010 Microchip Technology Inc.
DS41303G-page 149
PIC18F2XK20/4XK20
11.4.1
PWM PERIOD
The PWM period is specified by the PR2 register of
Timer2. The PWM period can be calculated using the
formula of Equation 11-1.
EQUATION 11-1:
PWM PERIOD
PWM Period =   PR2  + 1   4  T OSC 
(TMR2 Prescale Value)
Note: TOSC = 1/FOSC.
11.4.2
PWM DUTY CYCLE
The PWM duty cycle is specified by writing a 10-bit
value to multiple registers: CCPRxL register and
DCxB<1:0> bits of the CCPxCON register. The
CCPRxL contains the eight MSbs and the DCxB<1:0>
bits of the CCPxCON register contain the two LSbs.
CCPRxL and DCxB<1:0> bits of the CCPxCON
register can be written to at any time. The duty cycle
value is not latched into CCPRxH until after the period
completes (i.e., a match between PR2 and TMR2
registers occurs). While using the PWM, the CCPRxH
register is read-only.
When TMR2 is equal to PR2, the following three events
occur on the next increment cycle:
Equation 11-2 is used to calculate the PWM pulse
width.
• TMR2 is cleared
• The CCPx pin is set. (Exception: If the PWM duty
cycle = 0%, the pin will not be set.)
• The PWM duty cycle is latched from CCPRxL into
CCPRxH.
Equation 11-3 is used to calculate the PWM duty cycle
ratio.
EQUATION 11-2:
PULSE WIDTH
Pulse Width =  CCPRxL:DCxB<1:0>  
Note:
The Timer2 postscaler (see Section 14.1
“Timer2 Operation”) is not used in the
determination of the PWM frequency.
T OSC  (TMR2 Prescale Value)
EQUATION 11-3:
DUTY CYCLE RATIO
 CCPRxL:DCxB<1:0> 
Duty Cycle Ratio = ----------------------------------------------------------4  PR2 + 1 
The CCPRxH register and a 2-bit internal latch are
used to double buffer the PWM duty cycle. This double
buffering is essential for glitchless PWM operation.
The 8-bit timer TMR2 register is concatenated with
either the 2-bit internal system clock (FOSC), or 2 bits of
the prescaler, to create the 10-bit time base. The system
clock is used if the Timer2 prescaler is set to 1:1.
When the 10-bit time base matches the CCPRxH and
2-bit latch, then the CCPx pin is cleared (see
Figure 11-3).
DS41303G-page 150
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
11.4.3
PWM RESOLUTION
EQUATION 11-4:
The resolution determines the number of available duty
cycles for a given period. For example, a 10-bit resolution
will result in 1024 discrete duty cycles, whereas an 8-bit
resolution will result in 256 discrete duty cycles.
The maximum PWM resolution is 10 bits when PR2 is
255. The resolution is a function of the PR2 register
value as shown by Equation 11-4.
TABLE 11-4:
Timer Prescaler (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
Note:
If the pulse width value is greater than the
period the assigned PWM pin(s) will
remain unchanged.
2.44 kHz
9.77 kHz
39.06 kHz
156.25 kHz
312.50 kHz
416.67 kHz
16
4
1
1
1
1
FFh
FFh
FFh
3Fh
1Fh
17h
10
10
10
8
7
6.58
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 20 MHz)
PWM Frequency
Timer Prescale (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
TABLE 11-6:
log  4  PR2 + 1  
Resolution = ------------------------------------------ bits
log  2 
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
PWM Frequency
TABLE 11-5:
PWM RESOLUTION
1.22 kHz
4.88 kHz
19.53 kHz
78.12 kHz
156.3 kHz
208.3 kHz
16
4
1
1
1
1
0xFF
0xFF
0xFF
0x3F
0x1F
0x17
10
10
10
8
7
6.6
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 8 MHz)
PWM Frequency
Timer Prescale (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
 2010 Microchip Technology Inc.
1.22 kHz
4.90 kHz
19.61 kHz
76.92 kHz
153.85 kHz
200.0 kHz
16
4
1
1
1
1
0x65
0x65
0x65
0x19
0x0C
0x09
8
8
8
6
5
5
DS41303G-page 151
PIC18F2XK20/4XK20
11.4.4
OPERATION IN POWER-MANAGED
MODES
In Sleep mode, the TMR2 register will not increment
and the state of the module will not change. If the CCPx
pin is driving a value, it will continue to drive that value.
When the device wakes up, TMR2 will continue from its
previous state.
11.4.7
The following steps should be taken when configuring
the CCP module for PWM operation:
1.
2.
In PRI_IDLE mode, the primary clock will continue to
clock the CCP module without change. In all other
power-managed modes, the selected power-managed
mode clock will clock Timer2. Other power-managed
mode clocks will most likely be different than the
primary clock frequency.
3.
4.
11.4.5
5.
CHANGES IN SYSTEM CLOCK
FREQUENCY
The PWM frequency is derived from the system clock
frequency. Any changes in the system clock frequency
will result in changes to the PWM frequency. See
Section 2.0 “Oscillator Module (With Fail-Safe
Clock Monitor)” for additional details.
11.4.6
6.
EFFECTS OF RESET
Any Reset will force all ports to Input mode and the
CCP registers to their Reset states.
DS41303G-page 152
SETUP FOR PWM OPERATION
7.
Disable the PWM pin (CCPx) output drivers by
setting the associated TRIS bit.
For the ECCP module only: Select the desired
PWM outputs (P1A through P1D) by setting the
appropriate steering bits of the PSTRCON
register.
Set the PWM period by loading the PR2 register.
Configure the CCP module for the PWM mode
by loading the CCPxCON register with the
appropriate values.
Set the PWM duty cycle by loading the CCPRxL
register and CCPx bits of the CCPxCON register.
Configure and start Timer2:
• Clear the TMR2IF interrupt flag bit of the
PIR1 register.
• Set the Timer2 prescale value by loading the
T2CKPS bits of the T2CON register.
• Enable Timer2 by setting the TMR2ON bit of
the T2CON register.
Enable PWM output after a new PWM cycle has
started:
• Wait until Timer2 overflows (TMR2IF bit of
the PIR1 register is set).
• Enable the CCPx pin output driver by
clearing the associated TRIS bit.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 11-7:
Name
INTCON
REGISTERS ASSOCIATED WITH PWM AND TIMER2
Bit 7
Bit 6
GIE/GIEH PEIE/GIEL
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
—
RI
TO
PD
POR
BOR
58
IPEN
SBOREN
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE
(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
RCON
TRISB
PORTB Data Direction Control Register
62
TRISC
PORTC Data Direction Control Register
62
TMR2
Timer2 Register
60
PR2
Timer2 Period Register
60
T2CON
—
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
CCPR1L
Capture/Compare/PWM Register 1, Low Byte
CCPR1H
Capture/Compare/PWM Register 1, High Byte
CCP1CON
P1M1
P1M0
DC1B1
DC1B0
60
61
61
CCP1M3
CCP1M2
CCP1M1
CCP1M0
61
CCPR2L
Capture/Compare/PWM Register 2, Low Byte
61
CCPR2H
Capture/Compare/PWM Register 2, High Byte
61
CCP2CON
ECCP1AS
PWM1CON
—
—
ECCPASE ECCPAS2
PRSEN
PDC6
DC2B1
DC2B0
CCP2M3
CCP2M2
CCP2M1
CCP2M0
61
ECCPAS1
ECCPAS0
PSSAC1
PSSAC0
PSSBD1
PSSBD0
61
PDC5
PDC4
PDC3
PDC2
PDC
PDC0
61
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PWM or Timer2.
Note 1: Not implemented on PIC18F2XK20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 153
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 154
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
12.0
TIMER0 MODULE
The T0CON register (Register 12-1) controls all
aspects of the module’s operation, including the
prescale selection. It is both readable and writable.
The Timer0 module incorporates the following features:
A simplified block diagram of the Timer0 module in 8-bit
mode is shown in Figure 12-1. Figure 12-2 shows a
simplified block diagram of the Timer0 module in 16-bit
mode.
• Software selectable operation as a timer or counter in both 8-bit or 16-bit modes
• Readable and writable registers
• Dedicated 8-bit, software programmable
prescaler
• Selectable clock source (internal or external)
• Edge select for external clock
• Interrupt-on-overflow
REGISTER 12-1:
T0CON: TIMER0 CONTROL REGISTER
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
TMR0ON
T08BIT
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
TMR0ON: Timer0 On/Off Control bit
1 = Enables Timer0
0 = Stops Timer0
bit 6
T08BIT: Timer0 8-bit/16-bit Control bit
1 = Timer0 is configured as an 8-bit timer/counter
0 = Timer0 is configured as a 16-bit timer/counter
bit 5
T0CS: Timer0 Clock Source Select bit
1 = Transition on T0CKI pin
0 = Internal instruction cycle clock (CLKOUT)
bit 4
T0SE: Timer0 Source Edge Select bit
1 = Increment on high-to-low transition on T0CKI pin
0 = Increment on low-to-high transition on T0CKI pin
bit 3
PSA: Timer0 Prescaler Assignment bit
1 = TImer0 prescaler is NOT assigned. Timer0 clock input bypasses prescaler.
0 = Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output.
bit 2-0
T0PS<2:0>: Timer0 Prescaler Select bits
111 = 1:256 prescale value
110 = 1:128 prescale value
101 = 1:64 prescale value
100 = 1:32 prescale value
011 = 1:16 prescale value
010 = 1:8 prescale value
001 = 1:4 prescale value
000 = 1:2 prescale value
 2010 Microchip Technology Inc.
DS41303G-page 155
PIC18F2XK20/4XK20
12.1
Timer0 Operation
12.2
Timer0 can operate as either a timer or a counter; the
mode is selected with the T0CS bit of the T0CON
register. In Timer mode (T0CS = 0), the module
increments on every clock by default unless a different
prescaler value is selected (see Section 12.3
“Prescaler”). Timer0 incrementing is inhibited for two
instruction cycles following a TMR0 register write. The
user can work around this by adjusting the value written
to the TMR0 register to compensate for the anticipated
missing increments.
The Counter mode is selected by setting the T0CS bit
(= 1). In this mode, Timer0 increments either on every
rising or falling edge of pin RA4/T0CKI. The incrementing edge is determined by the Timer0 Source Edge
Select bit, T0SE of the T0CON register; clearing this bit
selects the rising edge. Restrictions on the external
clock input are discussed below.
Timer0 Reads and Writes in
16-Bit Mode
TMR0H is not the actual high byte of Timer0 in 16-bit
mode; it is actually a buffered version of the real high
byte of Timer0 which is neither directly readable nor
writable (refer to Figure 12-2). TMR0H is updated with
the contents of the high byte of Timer0 during a read of
TMR0L. This provides the ability to read all 16 bits of
Timer0 without the need to verify that the read of the
high and low byte were valid. Invalid reads could
otherwise occur due to a rollover between successive
reads of the high and low byte.
Similarly, a write to the high byte of Timer0 must also
take place through the TMR0H Buffer register. Writing
to TMR0H does not directly affect Timer0. Instead, the
high byte of Timer0 is updated with the contents of
TMR0H when a write occurs to TMR0L. This allows all
16 bits of Timer0 to be updated at once.
An external clock source can be used to drive Timer0;
however, it must meet certain requirements (see
Table 26-11) to ensure that the external clock can be
synchronized with the internal phase clock (TOSC).
There is a delay between synchronization and the
onset of incrementing the timer/counter.
FIGURE 12-1:
TIMER0 BLOCK DIAGRAM (8-BIT MODE)
FOSC/4
0
0
1
T0CKI pin
T0SE
T0CS
T0PS<2:0>
Programmable
Prescaler
1
Sync with
Internal
Clocks
TMR0L
(2 TCY Delay)
8
3
8
PSA
Note:
Set
TMR0IF
on Overflow
Internal Data Bus
Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
DS41303G-page 156
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 12-2:
TIMER0 BLOCK DIAGRAM (16-BIT MODE)
FOSC/4
0
0
Sync with
Internal
Clocks
1
Programmable
Prescaler
T0CKI pin
T0SE
T0CS
1
TMR0
High Byte
TMR0L
8
Set
TMR0IF
on Overflow
(2 TCY Delay)
3
Read TMR0L
T0PS<2:0>
Write TMR0L
PSA
8
8
TMR0H
8
8
Internal Data Bus
Note:
12.3
Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
12.3.1
Prescaler
An 8-bit counter is available as a prescaler for the Timer0
module. The prescaler is not directly readable or writable;
its value is set by the PSA and T0PS<2:0> bits of the
T0CON register which determine the prescaler
assignment and prescale ratio.
Clearing the PSA bit assigns the prescaler to the
Timer0 module. When the prescaler is assigned,
prescale values from 1:2 through 1:256 in integer
power-of-2 increments are selectable.
When assigned to the Timer0 module, all instructions
writing to the TMR0 register (e.g., CLRF TMR0, MOVWF
TMR0, BSF TMR0, etc.) clear the prescaler count.
Note:
Writing to TMR0 when the prescaler is
assigned to Timer0 will clear the prescaler
count but will not change the prescaler
assignment.
TABLE 12-1:
Name
SWITCHING PRESCALER
ASSIGNMENT
The prescaler assignment is fully under software
control and can be changed “on-the-fly” during program
execution.
12.4
Timer0 Interrupt
The TMR0 interrupt is generated when the TMR0 register overflows from FFh to 00h in 8-bit mode, or from
FFFFh to 0000h in 16-bit mode. This overflow sets the
TMR0IF flag bit. The interrupt can be masked by clearing the TMR0IE bit of the INTCON register. Before
re-enabling the interrupt, the TMR0IF bit must be
cleared by software in the Interrupt Service Routine.
Since Timer0 is shut down in Sleep mode, the TMR0
interrupt cannot awaken the processor from Sleep.
REGISTERS ASSOCIATED WITH TIMER0
Bit 7
Bit 6
Bit 5
TMR0L
Timer0 Register, Low Byte
TMR0H
Timer0 Register, High Byte
INTCON
GIE/GIEH PEIE/GIEL TMR0IE
T0CON
TMR0ON
T08BIT
TRISA
RA7(1)
RA6(1)
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
60
60
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
60
RA5
RA4
RA3
RA2
RA1
RA0
62
Legend: Shaded cells are not used by Timer0.
Note 1: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary
oscillator modes. When disabled, these bits read as ‘0’.
 2010 Microchip Technology Inc.
DS41303G-page 157
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 158
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
13.0
TIMER1 MODULE
The Timer1 timer/counter module incorporates the
following features:
• Software selectable operation as a 16-bit timer or
counter
• Readable and writable 8-bit registers (TMR1H
and TMR1L)
• Selectable internal or external clock source and
Timer1 oscillator options
• Interrupt-on-overflow
• Reset on CCP Special Event Trigger
• Device clock status flag (T1RUN)
REGISTER 13-1:
A simplified block diagram of the Timer1 module is
shown in Figure 13-1. A block diagram of the module’s
operation in Read/Write mode is shown in Figure 13-2.
The module incorporates its own low-power oscillator
to provide an additional clocking option. The Timer1
oscillator can also be used as a low-power clock source
for the microcontroller in power-managed operation.
Timer1 can also be used to provide Real-Time Clock
(RTC) functionality to applications with only a minimal
addition of external components and code overhead.
Timer1 is controlled through the T1CON Control
register (Register 13-1). It also contains the Timer1
Oscillator Enable bit (T1OSCEN). Timer1 can be
enabled or disabled by setting or clearing control bit,
TMR1ON of the T1CON register.
T1CON: TIMER1 CONTROL REGISTER
R/W-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
RD16
T1RUN
T1CKPS1
T1CKPS0
T1OSCEN
T1SYNC
TMR1CS
TMR1ON
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
RD16: 16-bit Read/Write Mode Enable bit
1 = Enables register read/write of TImer1 in one 16-bit operation
0 = Enables register read/write of Timer1 in two 8-bit operations
bit 6
T1RUN: Timer1 System Clock Status bit
1 = Main system clock is derived from Timer1 oscillator
0 = Main system clock is derived from another source
bit 5-4
T1CKPS<1:0>: Timer1 Input Clock Prescale Select bits
11 = 1:8 Prescale value
10 = 1:4 Prescale value
01 = 1:2 Prescale value
00 = 1:1 Prescale value
bit 3
T1OSCEN: Timer1 Oscillator Enable bit
1 = Timer1 oscillator is enabled
0 = Timer1 oscillator is shut off
The oscillator inverter and feedback resistor are turned off to eliminate power drain.
bit 2
T1SYNC: Timer1 External Clock Input Synchronization Select bit
When TMR1CS = 1:
1 = Do not synchronize external clock input
0 = Synchronize external clock input
When TMR1CS = 0:
This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.
bit 1
TMR1CS: Timer1 Clock Source Select bit
1 = External clock from pin RC0/T1OSO/T13CKI (on the rising edge)
0 = Internal clock (FOSC/4)
bit 0
TMR1ON: Timer1 On bit
1 = Enables Timer1
0 = Stops Timer1
 2010 Microchip Technology Inc.
DS41303G-page 159
PIC18F2XK20/4XK20
13.1
Timer1 Operation
instruction cycle (FOSC/4). When the bit is set, Timer1
increments on every rising edge of either the Timer1
external clock input or the Timer1 oscillator, if enabled.
Timer1 can operate in one of the following modes:
• Timer
• Synchronous Counter
• Asynchronous Counter
When the Timer1 oscillator is enabled, the digital
circuitry associated with the RC1/T1OSI and
RC0/T1OSO/T13CKI pins is disabled. This means the
values of TRISC<1:0> are ignored and the pins are
read as ‘0’.
The operating mode is determined by the clock select
bit, TMR1CS of the T1CON register. When TMR1CS is
cleared (= 0), Timer1 increments on every internal
FIGURE 13-1:
TIMER1 BLOCK DIAGRAM
Timer1 Oscillator
Timer1 Clock Input
1
On/Off
T1OSO/T13CKI
1
FOSC/4
Internal
Clock
T1OSI
Synchronize
Prescaler
1, 2, 4, 8
0
Detect
0
2
T1OSCEN(1)
Sleep Input
Timer1
On/Off
TMR1CS
T1CKPS<1:0>
T1SYNC
TMR1ON
Clear TMR1
(CCP Special Event Trigger)
Set
TMR1IF
on Overflow
TMR1
High Byte
TMR1L
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
FIGURE 13-2:
TIMER1 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Oscillator
Timer1 Clock Input
1
T1OSO/T13CKI
1
FOSC/4
Internal
Clock
T1OSI
Synchronize
Prescaler
1, 2, 4, 8
0
Detect
0
2
T1OSCEN(1)
T1CKPS<1:0>
T1SYNC
TMR1ON
Sleep Input
Timer1
On/Off
TMR1CS
Clear TMR1
(CCP Special Event Trigger)
TMR1
High Byte
TMR1L
8
Set
TMR1IF
on Overflow
Read TMR1L
Write TMR1L
8
8
TMR1H
8
8
Internal Data Bus
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
DS41303G-page 160
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
13.2
Clock Source Selection
The TMR1CS bit of the T1CON register is used to
select the clock source. When TMR1CS = 0, the clock
source is FOSC/4. When TMR1CS = 1, the clock source
is supplied externally.
13.2.1
INTERNAL CLOCK SOURCE
When the internal clock source is selected, the
TMR1H:TMR1L register pair will increment on multiples
of TCY as determined by the Timer1 prescaler.
13.2.2
EXTERNAL CLOCK SOURCE
When the external clock source is selected, the Timer1
module may work as a timer or a counter.
When counting, Timer1 is incremented on the rising
edge of the external clock input T1CKI. In addition, the
Counter mode clock can be synchronized to the
microcontroller system clock or run asynchronously.
If an external clock oscillator is needed (and the
microcontroller is using the INTOSC without CLKOUT),
Timer1 can use the LP oscillator as a clock source.
Note:
In Counter mode, a falling edge must be
registered by the counter prior to the first
incrementing rising edge after one or more
of the following conditions (see Figure 13-3):
• Timer1 is enabled after POR or BOR
Reset
• A write to TMR1H or TMR1L
• Timer1 is disabled (TMR1ON = 0)
when T1CKI is high then Timer1 is
enabled (TMR1ON = 1) when T1CKI
is low.
13.2.3
READING AND WRITING TIMER1 IN
ASYNCHRONOUS COUNTER
MODE
Reading TMR1H or TMR1L while the timer is running
from an external asynchronous clock will ensure a valid
read (taken care of in hardware). However, the user
should keep in mind that reading the 16-bit timer in two
8-bit values itself, poses certain problems, since the
timer may overflow between the reads.
For writes, it is recommended that the user simply stop
the timer and write the desired values. A write
contention may occur by writing to the timer registers,
while the register is incrementing. This may produce an
unpredictable value in the TMR1H:TTMR1L register
pair.
13.3
Timer1 Prescaler
Timer1 has four prescaler options allowing 1, 2, 4 or 8
divisions of the clock input. The T1CKPS bits of the
T1CON register control the prescale counter. The
prescale counter is not directly readable or writable;
however, the prescaler counter is cleared upon a write to
TMR1H or TMR1L.
13.4
Timer1 Operation in
Asynchronous Counter Mode
If control bit T1SYNC of the T1CON register is set, the
external clock input is not synchronized. The timer
continues to increment asynchronous to the internal
phase clocks. The timer will continue to run during
Sleep and can generate an interrupt on overflow,
which will wake-up the processor. However, special
precautions in software are needed to read/write the
timer (see Section 13.2.3 “Reading and Writing
Timer1 in Asynchronous Counter Mode”).
Note 1: When switching from synchronous to
asynchronous operation, it is possible to
skip an increment. When switching from
asynchronous to synchronous operation,
it is possible to produce an additional
increment.
FIGURE 13-3:
TIMER1 INCREMENTING EDGE
T1CKI = 1
when TMR1
Enabled
T1CKI = 0
when TMR1
Enabled
Note 1:
2:
Arrows indicate counter increments.
In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge of
the clock.
 2010 Microchip Technology Inc.
DS41303G-page 161
PIC18F2XK20/4XK20
13.5
Timer1 16-Bit Read/Write Mode
Timer1 can be configured for 16-bit reads and writes
(see Figure 13-2). When the RD16 control bit of the
T1CON register is set, the address for TMR1H is
mapped to a buffer register for the high byte of Timer1.
A read from TMR1L will load the contents of the high
byte of Timer1 into the Timer1 high byte buffer. This
provides the user with the ability to accurately read all
16 bits of Timer1 without the need to determine
whether a read of the high byte, followed by a read of
the low byte, has become invalid due to a rollover or
carry between reads.
TABLE 13-1:
Osc Type
LP
13.6
Timer1 Oscillator
An on-chip crystal oscillator circuit is incorporated
between pins T1OSI (input) and T1OSO (amplifier
output). It is enabled by setting the Timer1 Oscillator
Enable bit, T1OSCEN of the T1CON register. The
oscillator is a low-power circuit rated for 32 kHz crystals.
It will continue to run during all power-managed modes.
The circuit for a typical LP oscillator is shown in
Figure 13-4. Table 13-1 shows the capacitor selection
for the Timer1 oscillator.
The user must provide a software time delay to ensure
proper start-up of the Timer1 oscillator.
FIGURE 13-4:
EXTERNAL
COMPONENTS FOR THE
TIMER1 LP OSCILLATOR
C1
27 pF
PIC® MCU
Freq
C1
32 kHz
27 pF
C2
(1)
27 pF(1)
Note 1: Microchip suggests these values only as a
starting point in validating the oscillator
circuit.
2: Higher capacitance increases the stability
of the oscillator but also increases the
start-up time.
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate values of external
components.
Writing to TMR1H does not directly affect Timer1.
Instead, the high byte of Timer1 is updated with the
contents of TMR1H when a write occurs to TMR1L.
This allows all 16 bits of Timer1 to be updated at once.
The high byte of Timer1 is not directly readable or
writable in this mode. All reads and writes must take
place through the Timer1 High Byte Buffer register.
Writes to TMR1H do not clear the Timer1 prescaler.
The prescaler is only cleared on writes to TMR1L.
CAPACITOR SELECTION FOR
THE TIMER OSCILLATOR
4: Capacitor values are for design guidance
only.
13.6.1
USING TIMER1 AS A
CLOCK SOURCE
The Timer1 oscillator is also available as a clock
source in power-managed modes. By setting the clock
select bits, SCS<1:0> of the OSCCON register, to ‘01’,
the device switches to SEC_RUN mode; both the CPU
and peripherals are clocked from the Timer1 oscillator.
If the IDLEN bit of the OSCCON register is cleared and
a SLEEP instruction is executed, the device enters
SEC_IDLE mode. Additional details are available in
Section 3.0 “Power-Managed Modes”.
Whenever the Timer1 oscillator is providing the clock
source, the Timer1 system clock status flag, T1RUN of
the T1CON register, is set. This can be used to determine the controller’s current clocking mode. It can also
indicate which clock source is currently being used by
the Fail-Safe Clock Monitor. If the Clock Monitor is
enabled and the Timer1 oscillator fails while providing
the clock, polling the T1RUN bit will indicate whether
the clock is being provided by the Timer1 oscillator or
another source.
T1OSI
XTAL
32.768 kHz
T1OSO
C2
27 pF
Note:
See the Notes with Table 13-1 for additional
information about capacitor selection.
DS41303G-page 162
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
13.6.2
LOW-POWER TIMER1 OPTION
The Timer1 oscillator can operate at two distinct levels
of power consumption based on device configuration.
When the LPT1OSC Configuration bit of the
CONFIG3H register is set, the Timer1 oscillator operates in a low-power mode. When LPT1OSC is not set,
Timer1 operates at a higher power level. Power consumption for a particular mode is relatively constant,
regardless of the device’s operating mode. The default
Timer1 configuration is the higher power mode.
As the low-power Timer1 mode tends to be more
sensitive to interference, high noise environments may
cause some oscillator instability. The low-power option is,
therefore, best suited for low noise applications where
power conservation is an important design consideration.
13.6.3
TIMER1 OSCILLATOR LAYOUT
CONSIDERATIONS
The Timer1 oscillator circuit draws very little power
during operation. Due to the low-power nature of the
oscillator, it may also be sensitive to rapidly changing
signals in close proximity.
The oscillator circuit, shown in Figure 13-4, should be
located as close as possible to the microcontroller.
There should be no circuits passing within the oscillator
circuit boundaries other than VSS or VDD.
If a high-speed circuit must be located near the oscillator (such as the CCP1 pin in Output Compare or PWM
mode, or the primary oscillator using the OSC2 pin), a
grounded guard ring around the oscillator circuit, as
shown in Figure 13-5, may be helpful when used on a
single-sided PCB or in addition to a ground plane.
FIGURE 13-5:
13.7
Timer1 Interrupt
The TMR1 register pair (TMR1H:TMR1L) increments
from 0000h to FFFFh and rolls over to 0000h. The
Timer1 interrupt, if enabled, is generated on overflow,
which is latched in the TMR1IF interrupt flag bit of the
PIR1 register. This interrupt can be enabled or disabled
by setting or clearing the TMR1IE Interrupt Enable bit
of the PIE1 register.
13.8
Resetting Timer1 Using the CCP
Special Event Trigger
If either of the CCP modules is configured to use Timer1
and generate a Special Event Trigger in Compare mode
(CCP1M<3:0> or CCP2M<3:0> = 1011), this signal will
reset Timer1. The trigger from CCP2 will also start an
A/D conversion if the A/D module is enabled (see
Section 11.3.4 “Special Event Trigger” for more
information).
The module must be configured as either a timer or a
synchronous counter to take advantage of this feature.
When used this way, the CCPRH:CCPRL register pair
effectively becomes a period register for Timer1.
If Timer1 is running in Asynchronous Counter mode,
this Reset operation may not work.
In the event that a write to Timer1 coincides with a
special Event Trigger, the write operation will take
precedence.
Note:
The Special Event Triggers from the CCP2
module will not set the TMR1IF interrupt
flag bit of the PIR1 register.
OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
VDD
VSS
OSC1
OSC2
RC0
RC1
RC2
Note: Not drawn to scale.
 2010 Microchip Technology Inc.
DS41303G-page 163
PIC18F2XK20/4XK20
13.9
Using Timer1 as a Real-Time Clock
Adding an external LP oscillator to Timer1 (such as the
one described in Section 13.6 “Timer1 Oscillator”
above) gives users the option to include RTC functionality to their applications. This is accomplished with an
inexpensive watch crystal to provide an accurate time
base and several lines of application code to calculate
the time. When operating in Sleep mode and using a
battery or supercapacitor as a power source, it can
completely eliminate the need for a separate RTC
device and battery backup.
The application code routine, RTCisr, shown in
Example 13-1, demonstrates a simple method to
increment a counter at one-second intervals using an
Interrupt Service Routine. Incrementing the TMR1
register pair to overflow triggers the interrupt and calls
the routine, which increments the seconds counter by
one; additional counters for minutes and hours are
incremented on overflows of the less significant
counters.
EXAMPLE 13-1:
Since the register pair is 16 bits wide, a 32.768 kHz
clock source will take 2 seconds to count up to overflow. To force the overflow at the required one-second
intervals, it is necessary to preload it; the simplest
method is to set the MSb of TMR1H with a BSF instruction. Note that the TMR1L register is never preloaded
or altered; doing so may introduce cumulative error
over many cycles.
For this method to be accurate, Timer1 must operate in
Asynchronous mode and the Timer1 overflow interrupt
must be enabled (PIE1<0> = 1), as shown in the
routine, RTCinit. The Timer1 oscillator must also be
enabled and running at all times.
IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE
RTCinit
MOVLW
MOVWF
CLRF
MOVLW
MOVWF
CLRF
CLRF
MOVLW
MOVWF
BSF
RETURN
80h
TMR1H
TMR1L
b’00001111’
T1CON
secs
mins
.12
hours
PIE1, TMR1IE
BSF
BCF
INCF
MOVLW
CPFSGT
RETURN
CLRF
INCF
MOVLW
CPFSGT
RETURN
CLRF
INCF
MOVLW
CPFSGT
RETURN
CLRF
RETURN
TMR1H, 7
PIR1, TMR1IF
secs, F
.59
secs
; Preload TMR1 register pair
; for 1 second overflow
; Configure for external clock,
; Asynchronous operation, external oscillator
; Initialize timekeeping registers
;
; Enable Timer1 interrupt
RTCisr
DS41303G-page 164
secs
mins, F
.59
mins
mins
hours, F
.23
hours
hours
;
;
;
;
Preload for 1 sec overflow
Clear interrupt flag
Increment seconds
60 seconds elapsed?
;
;
;
;
No, done
Clear seconds
Increment minutes
60 minutes elapsed?
;
;
;
;
No, done
clear minutes
Increment hours
24 hours elapsed?
; No, done
; Reset hours
; Done
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 13-2:
Name
REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
(1)
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
TMR1L
Timer1 Register, Low Byte
60
TMR1H
Timer1 Register, High Byte
60
T1CON
RD16
T1RUN
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
TMR1CS
TMR1ON
60
Legend: Shaded cells are not used by the Timer1 module.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
 2010 Microchip Technology Inc.
DS41303G-page 165
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 166
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
14.0
TIMER2 MODULE
14.1
The Timer2 module timer incorporates the following
features:
• 8-bit timer and period registers (TMR2 and PR2,
respectively)
• Readable and writable (both registers)
• Software programmable prescaler (1:1, 1:4 and
1:16)
• Software programmable postscaler (1:1 through
1:16)
• Interrupt on TMR2-to-PR2 match
• Optional use as the shift clock for the MSSP
module
The module is controlled through the T2CON register
(Register 14-1), which enables or disables the timer
and configures the prescaler and postscaler. Timer2
can be shut off by clearing control bit, TMR2ON of the
T2CON register, to minimize power consumption.
A simplified block diagram of the module is shown in
Figure 14-1.
Timer2 Operation
In normal operation, TMR2 is incremented from 00h on
each clock (FOSC/4). A 4-bit counter/prescaler on the
clock input gives direct input, divide-by-4 and
divide-by-16 prescale options; these are selected by
the prescaler control bits, T2CKPS<1:0> of the T2CON
register. The value of TMR2 is compared to that of the
period register, PR2, on each clock cycle. When the
two values match, the comparator generates a match
signal as the timer output. This signal also resets the
value of TMR2 to 00h on the next cycle and drives the
output counter/postscaler (see Section 14.2 “Timer2
Interrupt”).
The TMR2 and PR2 registers are both directly readable
and writable. The TMR2 register is cleared on any
device Reset, whereas the PR2 register initializes to
FFh. Both the prescaler and postscaler counters are
cleared on the following events:
• a write to the TMR2 register
• a write to the T2CON register
• any device Reset (Power-on Reset, MCLR Reset,
Watchdog Timer Reset or Brown-out Reset)
TMR2 is not cleared when T2CON is written.
REGISTER 14-1:
T2CON: TIMER2 CONTROL REGISTER
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
T2OUTPS3
T2OUTPS2
T2OUTPS1
T2OUTPS0
TMR2ON
T2CKPS1
T2CKPS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
Unimplemented: Read as ‘0’
bit 6-3
T2OUTPS<3:0>: Timer2 Output Postscale Select bits
0000 = 1:1 Postscale
0001 = 1:2 Postscale
•
•
•
1111 = 1:16 Postscale
bit 2
TMR2ON: Timer2 On bit
1 = Timer2 is on
0 = Timer2 is off
bit 1-0
T2CKPS<1:0>: Timer2 Clock Prescale Select bits
00 = Prescaler is 1
01 = Prescaler is 4
1x = Prescaler is 16
 2010 Microchip Technology Inc.
x = Bit is unknown
DS41303G-page 167
PIC18F2XK20/4XK20
14.2
Timer2 Interrupt
14.3
Timer2 can also generate an optional device interrupt.
The Timer2 output signal (TMR2-to-PR2 match) provides the input for the 4-bit output counter/postscaler.
This counter generates the TMR2 match interrupt flag
which is latched in TMR2IF of the PIR1 register. The
interrupt is enabled by setting the TMR2 Match Interrupt Enable bit, TMR2IE of the PIE1 register.
Timer2 Output
The unscaled output of TMR2 is available primarily to
the CCP modules, where it is used as a time base for
operations in PWM mode.
Timer2 can be optionally used as the shift clock source
for the MSSP module operating in SPI mode. Additional information is provided in Section 17.0 “Master
Synchronous Serial Port (MSSP) Module”.
A range of 16 postscale options (from 1:1 through 1:16
inclusive) can be selected with the postscaler control
bits, T2OUTPS<3:0> of the T2CON register.
FIGURE 14-1:
TIMER2 BLOCK DIAGRAM
4
1:1 to 1:16
Postscaler
T2OUTPS<3:0>
Set TMR2IF
2
TMR2 Output
(to PWM or MSSP)
T2CKPS<1:0>
1:1, 1:4, 1:16
Prescaler
FOSC/4
TMR2/PR2
Match
Reset
TMR2
Comparator
8
PR2
8
8
Internal Data Bus
TABLE 14-1:
Name
REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER
Bit 7
Bit 6
INTCON GIE/GIEH PEIE/GIEL
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
TMR2
T2CON
PR2
Timer2 Register
—
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON
62
60
T2CKPS1 T2CKPS0
Timer2 Period Register
60
60
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer2 module.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
DS41303G-page 168
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
15.0
TIMER3 MODULE
The Timer3 module timer/counter incorporates these
features:
• Software selectable operation as a 16-bit timer or
counter
• Readable and writable 8-bit registers (TMR3H
and TMR3L)
• Selectable clock source (internal or external) with
device clock or Timer1 oscillator internal options
• Interrupt-on-overflow
• Module Reset on CCP Special Event Trigger
REGISTER 15-1:
A simplified block diagram of the Timer3 module is
shown in Figure 15-1. A block diagram of the module’s
operation in Read/Write mode is shown in Figure 15-2.
The Timer3 module is controlled through the T3CON
register (Register 15-1). It also selects the clock source
options for the CCP modules (see Section 11.1.1
“CCP Modules and Timer Resources” for more
information).
T3CON: TIMER3 CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
RD16
T3CCP2
T3CKPS1
T3CKPS0
T3CCP1
T3SYNC
TMR3CS
TMR3ON
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
RD16: 16-bit Read/Write Mode Enable bit
1 = Enables register read/write of Timer3 in one 16-bit operation
0 = Enables register read/write of Timer3 in two 8-bit operations
bit 6,3
T3CCP<2:1>: Timer3 and Timer1 to CCPx Enable bits
1x = Timer3 is the capture/compare clock source for CCP1 and CP2
01 = Timer3 is the capture/compare clock source for CCP2 and
Timer1 is the capture/compare clock source for CCP1
00 = Timer1 is the capture/compare clock source for CCP1 and CP2
bit 5-4
T3CKPS<1:0>: Timer3 Input Clock Prescale Select bits
11 = 1:8 Prescale value
10 = 1:4 Prescale value
01 = 1:2 Prescale value
00 = 1:1 Prescale value
bit 2
T3SYNC: Timer3 External Clock Input Synchronization Control bit
(Not usable if the device clock comes from Timer1/Timer3.)
When TMR3CS = 1:
1 = Do not synchronize external clock input
0 = Synchronize external clock input
When TMR3CS = 0:
This bit is ignored. Timer3 uses the internal clock when TMR3CS = 0.
bit 1
TMR3CS: Timer3 Clock Source Select bit
1 = External clock input from Timer1 oscillator or T13CKI (on the rising edge after the first
falling edge)
0 = Internal clock (FOSC/4)
bit 0
TMR3ON: Timer3 On bit
1 = Enables Timer3
0 = Stops Timer3
 2010 Microchip Technology Inc.
DS41303G-page 169
PIC18F2XK20/4XK20
15.1
Timer3 Operation
The operating mode is determined by the clock select
bit, TMR3CS of the T3CON register. When TMR3CS is
cleared (= 0), Timer3 increments on every internal
instruction cycle (FOSC/4). When the bit is set, Timer3
increments on every rising edge of the Timer1 external
clock input or the Timer1 oscillator, if enabled.
Timer3 can operate in one of three modes:
• Timer
• Synchronous Counter
• Asynchronous Counter
As with Timer1, the digital circuitry associated with the
RC1/T1OSI and RC0/T1OSO/T13CKI pins is disabled
when the Timer1 oscillator is enabled. This means the
values of TRISC<1:0> are ignored and the pins are
read as ‘0’.
FIGURE 15-1:
TIMER3 BLOCK DIAGRAM
Timer1 Oscillator
Timer1 Clock Input
1
T1OSO/T13CKI
1
FOSC/4
Internal
Clock
T1OSI
Synchronize
Prescaler
1, 2, 4, 8
Detect
0
0
2
T1OSCEN
(1)
Sleep Input
TMR3CS
T3CKPS<1:0>
Timer3
On/Off
T3SYNC
TMR3ON
CCP1/CCP2 Special Event Trigger
CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
TMR3L
TMR3
High Byte
Set
TMR3IF
on Overflow
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
DS41303G-page 170
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 15-2:
TIMER3 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Oscillator
Timer1 Clock Input
1
T13CKI/T1OSO
1
FOSC/4
Internal
Clock
T1OSI
Synchronize
Prescaler
1, 2, 4, 8
0
Detect
0
2
(1)
T1OSCEN
T3CKPS<1:0>
T3SYNC
TMR3ON
Sleep Input
Timer3
On/Off
TMR3CS
CCP1/CCP2 Special Event Trigger
CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
Set
TMR3IF
on Overflow
TMR3
High Byte
TMR3L
8
Read TMR1L
Write TMR1L
8
8
TMR3H
8
8
Internal Data Bus
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
15.2
Timer3 16-Bit Read/Write Mode
Timer3 can be configured for 16-bit reads and writes
(see Figure 15-2). When the RD16 control bit of the
T3CON register is set, the address for TMR3H is
mapped to a buffer register for the high byte of Timer3.
A read from TMR3L will load the contents of the high
byte of Timer3 into the Timer3 High Byte Buffer register. This provides the user with the ability to accurately
read all 16 bits of Timer1 without having to determine
whether a read of the high byte, followed by a read of
the low byte, has become invalid due to a rollover
between reads.
A write to the high byte of Timer3 must also take place
through the TMR3H Buffer register. The Timer3 high
byte is updated with the contents of TMR3H when a
write occurs to TMR3L. This allows a user to write all
16 bits to both the high and low bytes of Timer3 at once.
The high byte of Timer3 is not directly readable or
writable in this mode. All reads and writes must take
place through the Timer3 High Byte Buffer register.
Writes to TMR3H do not clear the Timer3 prescaler.
The prescaler is only cleared on writes to TMR3L.
 2010 Microchip Technology Inc.
15.3
Using the Timer1 Oscillator as the
Timer3 Clock Source
The Timer1 internal oscillator may be used as the clock
source for Timer3. The Timer1 oscillator is enabled by
setting the T1OSCEN bit of the T1CON register. To use
it as the Timer3 clock source, the TMR3CS bit must
also be set. As previously noted, this also configures
Timer3 to increment on every rising edge of the
oscillator source.
The Timer1 oscillator is described in Section 13.0
“Timer1 Module”.
15.4
Timer3 Interrupt
The TMR3 register pair (TMR3H:TMR3L) increments
from 0000h to FFFFh and overflows to 0000h. The
Timer3 interrupt, if enabled, is generated on overflow
and is latched in interrupt flag bit, TMR3IF of the PIR2
register. This interrupt can be enabled or disabled by
setting or clearing the Timer3 Interrupt Enable bit,
TMR3IE of the PIE2 register.
DS41303G-page 171
PIC18F2XK20/4XK20
15.5
Resetting Timer3 Using the CCP
Special Event Trigger
If either of the CCP modules is configured to use
Timer3 and to generate a Special Event Trigger
in Compare mode (CCP1M<3:0> or CCP2M<3:0> =
1011), this signal will reset Timer3. It will also start an
A/D conversion if the A/D module is enabled (see
Section 11.3.4 “Special Event Trigger” for more
information).
The module must be configured as either a timer or
synchronous counter to take advantage of this feature.
When used this way, the CCPR2H:CCPR2L register
pair effectively becomes a period register for Timer3.
If Timer3 is running in Asynchronous Counter mode,
the Reset operation may not work.
In the event that a write to Timer3 coincides with a
Special Event Trigger from a CCP module, the write will
take precedence.
Note:
The Special Event Triggers from the CCP2
module will not set the TMR3IF interrupt
flag bit of the PIR2 register.
TABLE 15-1:
Name
INTCON
REGISTERS ASSOCIATED WITH TIMER3 AS A TIMER/COUNTER
Bit 7
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
Bit 6
GIE/GIEH PEIE/GIEL
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
TMR3L
Timer3 Register, Low Byte
TMR3H
Timer3 Register, High Byte
61
61
T1CON
RD16
T1RUN
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
TMR1CS
TMR1ON
60
T3CON
RD16
T3CCP2
T3CKPS1 T3CKPS0
TMR3CS
TMR3ON
61
T3CCP1
T3SYNC
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer3 module.
DS41303G-page 172
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.0
ENHANCED
CAPTURE/COMPARE/PWM
(ECCP) MODULE
CCP1 is implemented as a standard CCP module with
enhanced PWM capabilities. These include:
•
•
•
•
•
Provision for 2 or 4 output channels
Output steering
Programmable polarity
Programmable dead-band control
Automatic shutdown and restart.
REGISTER 16-1:
The enhanced features are discussed in detail in
Section 16.4 “PWM (Enhanced Mode)”. Capture,
Compare and single-output PWM functions of the
ECCP module are the same as described for the
standard CCP module.
The control register for the enhanced CCP module is
shown in Register 16-1. It differs from the CCP2CON
register in that the two Most Significant bits are
implemented to control PWM functionality.
CCP1CON: ENHANCED CAPTURE/COMPARE/PWM CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
P1M1
P1M0
DC1B1
DC1B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
P1M<1:0>: Enhanced PWM Output Configuration bits
If CCP1M<3:2> = 00, 01, 10:
xx = P1A assigned as Capture/Compare input/output; P1B, P1C, P1D assigned as port pins
If CCP1M<3:2> = 11:
00 = Single output: P1A, P1B, P1C and P1D controlled by steering (See Section 16.4.7 “Pulse Steering
Mode”).
01 = Full-bridge output forward: P1D modulated; P1A active; P1B, P1C inactive
10 = Half-bridge output: P1A, P1B modulated with dead-band control; P1C, P1D assigned as port pins
11 = Full-bridge output reverse: P1B modulated; P1C active; P1A, P1D inactive
bit 5-4
DC1B<1:0>: PWM Duty Cycle bit 1 and bit 0
Capture mode:
Unused.
Compare mode:
Unused.
PWM mode:
These bits are the two LSbs of the 10-bit PWM duty cycle. The eight MSbs of the duty cycle are found in
CCPR1L.
bit 3-0
CCP1M<3:0>: Enhanced CCP Mode Select bits
0000 = Capture/Compare/PWM off (resets ECCP module)
0001 = Reserved
0010 = Compare mode, toggle output on match
0011 = Reserved
0100 = Capture mode, every falling edge
0101 = Capture mode, every rising edge
0110 = Capture mode, every 4th rising edge
0111 = Capture mode, every 16th rising edge
1000 = Compare mode, initialize CCP1 pin low, set output on compare match (set CCP1IF)
1001 = Compare mode, initialize CCP1 pin high, clear output on compare match (set CCP1IF)
1010 = Compare mode, generate software interrupt only, CCP1 pin reverts to I/O state
1011 = Compare mode, trigger special event (ECCP resets TMR1 or TMR3, sets CC1IF bit)
1100 = PWM mode; P1A, P1C active-high; P1B, P1D active-high
1101 = PWM mode; P1A, P1C active-high; P1B, P1D active-low
1110 = PWM mode; P1A, P1C active-low; P1B, P1D active-high
1111 = PWM mode; P1A, P1C active-low; P1B, P1D active-low
 2010 Microchip Technology Inc.
DS41303G-page 173
PIC18F2XK20/4XK20
In addition to the expanded range of modes available
through the CCP1CON register and ECCP1AS
register, the ECCP module has two additional registers
associated with Enhanced PWM operation and
auto-shutdown features. They are:
• PWM1CON (Dead-band delay)
• PSTRCON (output steering)
16.1
16.3
Standard PWM Mode
When configured in Single Output mode, the ECCP
module functions identically to the standard CCP
module in PWM mode, as described in Section 11.4
“PWM Mode”. This is also sometimes referred to as
“Single CCP” mode, as in Table 16-1.
ECCP Outputs and Configuration
The enhanced CCP module may have up to four PWM
outputs, depending on the selected operating mode.
These outputs, designated P1A through P1D, are
multiplexed with I/O pins on PORTC and PORTD (for
PIC18F4XK20 devices) or PORTB (for PIC18F2XK20
devices). The outputs that are active depend on the
CCP operating mode selected. The pin assignments
are summarized in Table 16-1.
To configure the I/O pins as PWM outputs, the proper
PWM mode must be selected by setting the P1M<1:0>
and CCP1M<3:0> bits. The appropriate TRISC and
TRISD direction bits for the port pins must also be set
as outputs.
16.1.1
ECCP MODULES AND TIMER
RESOURCES
Like the standard CCP modules, the ECCP module can
utilize Timers 1, 2 or 3, depending on the mode
selected. Timer1 and Timer3 are available for modules
in Capture or Compare modes, while Timer2 is
available for modules in PWM mode. Interactions
between the standard and enhanced CCP modules are
identical to those described for standard CCP modules.
Additional details on timer resources are provided in
Section 11.1.1
“CCP
Modules
and
Timer
Resources”.
16.2
Capture and Compare Modes
Except for the operation of the Special Event Trigger
discussed below, the Capture and Compare modes of
the ECCP module are identical in operation to that of
CCP2. These are discussed in detail in Section 11.2
“Capture Mode” and Section 11.3 “Compare
Mode”. No changes are required when moving
between 28-pin and 40/44-pin devices.
16.2.1
SPECIAL EVENT TRIGGER
The Special Event Trigger output of ECCP1 resets the
TMR1 or TMR3 register pair, depending on which timer
resource is currently selected. This allows the CCPR1
register to effectively be a 16-bit programmable period
register for Timer1 or Timer3.
DS41303G-page 174
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.4
PWM (Enhanced Mode)
The PWM outputs are multiplexed with I/O pins and are
designated P1A, P1B, P1C and P1D. The polarity of the
PWM pins is configurable and is selected by setting the
CCP1M bits in the CCP1CON register appropriately.
The Enhanced PWM Mode can generate a PWM signal
on up to four different output pins with up to 10-bits of
resolution. It can do this through four different PWM
output modes:
•
•
•
•
Table 16-1 shows the pin assignments for each
Enhanced PWM mode.
Single PWM
Half-Bridge PWM
Full-Bridge PWM, Forward mode
Full-Bridge PWM, Reverse mode
Figure 16-1 shows an example of a simplified block
diagram of the Enhanced PWM module.
Note:
To prevent the generation of an
incomplete waveform when the PWM is
first enabled, the ECCP module waits until
the start of a new PWM period before
generating a PWM signal.
To select an Enhanced PWM mode, the P1M bits of the
CCP1CON register must be set appropriately.
Note:
The PWM Enhanced mode is available on
the Enhanced Capture/Compare/PWM
module (CCP1) only.
FIGURE 16-1:
EXAMPLE SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODE
Duty Cycle Registers
DC1B<1:0>
CCP1M<3:0>
4
P1M<1:0>
2
CCPR1L
CCP1/P1A
CCP1/P1A
TRIS
CCPR1H (Slave)
P1B
R
Comparator
Output
Controller
Q
P1B
TRIS
P1C
TMR2
(1)
S
P1D
Comparator
Clear Timer2,
toggle PWM pin and
latch duty cycle
PR2
Note
1:
P1C
TRIS
P1D
TRIS
PWM1CON
The 8-bit timer TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler to create the 10-bit
time base.
Note 1: The TRIS register value for each PWM output must be configured appropriately.
2: Clearing the CCPxCON register will relinquish ECCP control of all PWM output pins.
3: Any pin not used by an Enhanced PWM mode is available for alternate pin functions.
TABLE 16-1:
EXAMPLE PIN ASSIGNMENTS FOR VARIOUS PWM ENHANCED MODES
ECCP Mode
P1M<1:0>
CCP1/P1A
Single
00
Yes(1)
Half-Bridge
10
Yes
Yes
No
No
Full-Bridge, Forward
01
Yes
Yes
Yes
Yes
Full-Bridge, Reverse
11
Yes
Yes
Yes
Yes
Note 1:
P1B
Yes
(1)
P1C
Yes
(1)
P1D
Yes(1)
Outputs are enabled by pulse steering in Single mode. See Register 16-4.
 2010 Microchip Technology Inc.
DS41303G-page 175
PIC18F2XK20/4XK20
FIGURE 16-2:
EXAMPLE PWM (ENHANCED MODE) OUTPUT RELATIONSHIPS (ACTIVE-HIGH
STATE)
P1M<1:0>
Signal
PR2+1
Pulse
Width
0
Period
00
(Single Output)
P1A Modulated
Delay(1)
Delay(1)
P1A Modulated
10
(Half-Bridge)
P1B Modulated
P1A Active
01
(Full-Bridge,
Forward)
P1B Inactive
P1C Inactive
P1D Modulated
P1A Inactive
11
(Full-Bridge,
Reverse)
P1B Modulated
P1C Active
P1D Inactive
Relationships:
• Period = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value)
• Pulse Width = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale Value)
• Delay = 4 * TOSC * (PWM1CON<6:0>)
Note 1: Dead-band delay is programmed using the PWM1CON register (Section 16.4.6 “Programmable Dead-Band Delay
mode”).
DS41303G-page 176
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 16-3:
EXAMPLE ENHANCED PWM OUTPUT RELATIONSHIPS (ACTIVE-LOW STATE)
Signal
P1M<1:0>
PR2+1
Pulse
Width
0
Period
00
(Single Output)
P1A Modulated
P1A Modulated
Delay(1)
10
(Half-Bridge)
Delay(1)
P1B Modulated
P1A Active
01
(Full-Bridge,
Forward)
P1B Inactive
P1C Inactive
P1D Modulated
P1A Inactive
11
(Full-Bridge,
Reverse)
P1B Modulated
P1C Active
P1D Inactive
Relationships:
• Period = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value)
• Pulse Width = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale Value)
• Delay = 4 * TOSC * (PWM1CON<6:0>)
Note
1:
Dead-band delay is programmed using the PWM1CON register (Section 16.4.6 “Programmable Dead-Band Delay
mode”).
 2010 Microchip Technology Inc.
DS41303G-page 177
PIC18F2XK20/4XK20
16.4.1
HALF-BRIDGE MODE
In Half-Bridge mode, two pins are used as outputs to
drive push-pull loads. The PWM output signal is output
on the CCPx/P1A pin, while the complementary PWM
output signal is output on the P1B pin (see
Figure 16-5). This mode can be used for Half-Bridge
applications, as shown in Figure 16-5, or for Full-Bridge
applications, where four power switches are being
modulated with two PWM signals.
In Half-Bridge mode, the programmable dead-band delay
can be used to prevent shoot-through current in
Half-Bridge power devices. The value of the PDC<6:0>
bits of the PWM1CON register sets the number of
instruction cycles before the output is driven active. If the
value is greater than the duty cycle, the corresponding
output remains inactive during the entire cycle. See
Section 16.4.6 “Programmable Dead-Band Delay
mode” for more details of the dead-band delay
operations.
Since the P1A and P1B outputs are multiplexed with
the PORT data latches, the associated TRIS bits must
be cleared to configure P1A and P1B as outputs.
FIGURE 16-4:
Period
Period
Pulse Width
P1A(2)
td
td
P1B(2)
(1)
(1)
(1)
td = Dead-Band Delay
Note 1:
2:
FIGURE 16-5:
EXAMPLE OF
HALF-BRIDGE PWM
OUTPUT
At this time, the TMR2 register is equal to the
PR2 register.
Output signals are shown as active-high.
EXAMPLE OF HALF-BRIDGE APPLICATIONS
Standard Half-Bridge Circuit (“Push-Pull”)
FET
Driver
+
P1A
Load
FET
Driver
+
P1B
-
Half-Bridge Output Driving a Full-Bridge Circuit
V+
FET
Driver
FET
Driver
P1A
FET
Driver
Load
FET
Driver
P1B
DS41303G-page 178
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.4.2
FULL-BRIDGE MODE
In Full-Bridge mode, all four pins are used as outputs.
An example of Full-Bridge application is shown in
Figure 16-6.
In the Forward mode, pin CCP1/P1A is driven to its
active state, pin P1D is modulated, while P1B and P1C
will be driven to their inactive state as shown in
Figure 16-7.
In the Reverse mode, P1C is driven to its active state,
pin P1B is modulated, while P1A and P1D will be driven
to their inactive state as shown Figure 16-7.
P1A, P1B, P1C and P1D outputs are multiplexed with
the PORT data latches. The associated TRIS bits must
be cleared to configure the P1A, P1B, P1C and P1D
pins as outputs.
FIGURE 16-6:
EXAMPLE OF FULL-BRIDGE APPLICATION
V+
FET
Driver
QC
QA
FET
Driver
P1A
Load
P1B
FET
Driver
P1C
FET
Driver
QD
QB
VP1D
 2010 Microchip Technology Inc.
DS41303G-page 179
PIC18F2XK20/4XK20
FIGURE 16-7:
EXAMPLE OF FULL-BRIDGE PWM OUTPUT
Forward Mode
Period
P1A
(2)
Pulse Width
P1B(2)
P1C(2)
P1D(2)
(1)
(1)
Reverse Mode
Period
Pulse Width
P1A(2)
P1B(2)
P1C(2)
P1D(2)
(1)
Note 1:
2:
(1)
At this time, the TMR2 register is equal to the PR2 register.
Output signal is shown as active-high.
DS41303G-page 180
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.4.2.1
Direction Change in Full-Bridge
Mode
In the Full-Bridge mode, the P1M1 bit in the CCP1CON
register allows users to control the forward/reverse
direction. When the application firmware changes this
direction control bit, the module will change to the new
direction on the next PWM cycle.
A direction change is initiated in software by changing
the P1M1 bit of the CCP1CON register. The following
sequence occurs prior to the end of the current PWM
period:
• The modulated outputs (P1B and P1D) are placed
in their inactive state.
• The associated unmodulated outputs (P1A and
P1C) are switched to drive in the opposite
direction.
• PWM modulation resumes at the beginning of the
next period.
See Figure 16-8 for an illustration of this sequence.
The Full-Bridge mode does not provide dead-band
delay. As one output is modulated at a time, dead-band
delay is generally not required. There is a situation
where dead-band delay is required. This situation
occurs when both of the following conditions are true:
1.
2.
The direction of the PWM output changes when
the duty cycle of the output is at or near 100%.
The turn off time of the power switch, including
the power device and driver circuit, is greater
than the turn on time.
Figure 16-9 shows an example of the PWM direction
changing from forward to reverse, at a near 100% duty
cycle. In this example, at time t1, the output P1A and
P1D become inactive, while output P1C becomes
active. Since the turn off time of the power devices is
longer than the turn on time, a shoot-through current
will flow through power devices QC and QD (see
Figure 16-6) for the duration of ‘t’. The same
phenomenon will occur to power devices QA and QB
for PWM direction change from reverse to forward.
If changing PWM direction at high duty cycle is required
for an application, two possible solutions for eliminating
the shoot-through current are:
1.
2.
Reduce PWM duty cycle for one PWM period
before changing directions.
Use switch drivers that can drive the switches off
faster than they can drive them on.
Other options to prevent shoot-through current may
exist.
FIGURE 16-8:
EXAMPLE OF PWM DIRECTION CHANGE
Period(1)
Signal
Period
P1A (Active-High)
P1B (Active-High)
Pulse Width
P1C (Active-High)
(2)
P1D (Active-High)
Pulse Width
Note 1:
2:
The direction bit P1M1 of the CCP1CON register is written any time during the PWM cycle.
When changing directions, the P1A and P1C signals switch before the end of the current PWM cycle. The
modulated P1B and P1D signals are inactive at this time. The length of this time is (1/FOSC)  TMR2 prescale
value.
 2010 Microchip Technology Inc.
DS41303G-page 181
PIC18F2XK20/4XK20
FIGURE 16-9:
EXAMPLE OF PWM DIRECTION CHANGE AT NEAR 100% DUTY CYCLE
Forward Period
t1
Reverse Period
P1A
P1B
PW
P1C
P1D
PW
TON
External Switch C
TOFF
External Switch D
Potential
Shoot-Through Current
Note 1:
16.4.3
T = TOFF – TON
All signals are shown as active-high.
2:
TON is the turn on delay of power switch QC and its driver.
3:
TOFF is the turn off delay of power switch QD and its driver.
START-UP CONSIDERATIONS
When any PWM mode is used, the application
hardware must use the proper external pull-up and/or
pull-down resistors on the PWM output pins.
Note:
When the microcontroller is released from
Reset, all of the I/O pins are in the
high-impedance state. The external circuits must keep the power switch devices
in the Off state until the microcontroller
drives the I/O pins with the proper signal
levels or activates the PWM output(s).
The CCP1M<1:0> bits of the CCP1CON register allow
the user to choose whether the PWM output signals are
active-high or active-low for each pair of PWM output pins
(P1A/P1C and P1B/P1D). The PWM output polarities
must be selected before the PWM pin output drivers are
enabled. Changing the polarity configuration while the
PWM pin output drivers are enable is not recommended
since it may result in damage to the application circuits.
The P1A, P1B, P1C and P1D output latches may not be
in the proper states when the PWM module is
initialized. Enabling the PWM pin output drivers at the
same time as the Enhanced PWM modes may cause
damage to the application circuit. The Enhanced PWM
modes must be enabled in the proper Output mode and
complete a full PWM cycle before enabling the PWM
pin output drivers. The completion of a full PWM cycle
is indicated by the TMR2IF bit of the PIR1 register
being set as the second PWM period begins.
DS41303G-page 182
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.4.4
ENHANCED PWM
AUTO-SHUTDOWN MODE
The PWM mode supports an Auto-Shutdown mode that
will disable the PWM outputs when an external
shutdown event occurs. Auto-Shutdown mode places
the PWM output pins into a predetermined state. This
mode is used to help prevent the PWM from damaging
the application.
The auto-shutdown sources are selected using the
ECCPAS<2:0> bits of the ECCP1AS register. A
shutdown event may be generated by:
•
•
•
•
A logic ‘0’ on the FLT0 pin
Comparator C1
Comparator C2
Setting the ECCPASE bit in firmware
REGISTER 16-2:
A shutdown condition is indicated by the ECCPASE
(Auto-Shutdown Event Status) bit of the ECCP1AS
register. If the bit is a ‘0’, the PWM pins are operating
normally. If the bit is a ‘1’, the PWM outputs are in the
shutdown state.
When a shutdown event occurs, two things happen:
The ECCPASE bit is set to ‘1’. The ECCPASE will
remain set until cleared in firmware or an auto-restart
occurs (see Section 16.4.5 “Auto-Restart Mode”).
The enabled PWM pins are asynchronously placed in
their shutdown states. The PWM output pins are
grouped into pairs [P1A/P1C] and [P1B/P1D]. The state
of each pin pair is determined by the PSSAC and
PSSBD bits of the ECCP1AS register. Each pin pair may
be placed into one of three states:
• Drive logic ‘1’
• Drive logic ‘0’
• Tri-state (high-impedance)
ECCP1AS: ENHANCED CAPTURE/COMPARE/PWM AUTO-SHUTDOWN
CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ECCPASE
ECCPAS2
ECCPAS1
ECCPAS0
PSSAC1
PSSAC0
PSSBD1
PSSBD0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
ECCPASE: ECCP Auto-Shutdown Event Status bit
1 = A shutdown event has occurred; ECCP outputs are in shutdown state
0 = ECCP outputs are operating
bit 6-4
ECCPAS<2:0>: ECCP Auto-shutdown Source Select bits
000 = Auto-Shutdown is disabled
001 = Comparator C1OUT output is high
010 = Comparator C2OUT output is high
011 = Either Comparator C1OUT or C2OUT is high
100 = VIL on FLT0 pin
101 = VIL on FLT0 pin or Comparator C1OUT output is high
110 = VIL on FLT0 pin or Comparator C2OUT output is high
111 = VIL on FLT0 pin or Comparator C1OUT or Comparator C2OUT is high
bit 3-2
PSSACn: Pins P1A and P1C Shutdown State Control bits
00 = Drive pins P1A and P1C to ‘0’
01 = Drive pins P1A and P1C to ‘1’
1x = Pins P1A and P1C tri-state
bit 1-0
PSSBDn: Pins P1B and P1D Shutdown State Control bits
00 = Drive pins P1B and P1D to ‘0’
01 = Drive pins P1B and P1D to ‘1’
1x = Pins P1B and P1D tri-state
 2010 Microchip Technology Inc.
DS41303G-page 183
PIC18F2XK20/4XK20
Note 1: The auto-shutdown condition is a
level-based signal, not an edge-based
signal. As long as the level is present, the
auto-shutdown will persist.
2: Writing to the ECCPASE bit is disabled
while an auto-shutdown condition
persists.
3: Once the auto-shutdown condition has
been removed and the PWM restarted
(either through firmware or auto-restart)
the PWM signal will always restart at the
beginning of the next PWM period.
FIGURE 16-10:
PWM AUTO-SHUTDOWN WITH FIRMWARE RESTART (PRSEN = 0)
PWM Period
Shutdown Event
ECCPASE bit
PWM Activity
Normal PWM
ECCPASE
Cleared by
Shutdown
Shutdown Firmware PWM
Event Occurs Event Clears
Resumes
Start of
PWM Period
16.4.5
AUTO-RESTART MODE
The Enhanced PWM can be configured to automatically restart the PWM signal once the auto-shutdown
condition has been removed. Auto-restart is enabled by
setting the PRSEN bit in the PWM1CON register.
If auto-restart is enabled, the ECCPASE bit will remain
set as long as the auto-shutdown condition is active.
When the auto-shutdown condition is removed, the
ECCPASE bit will be cleared via hardware and normal
operation will resume.
FIGURE 16-11:
PWM AUTO-SHUTDOWN WITH AUTO-RESTART ENABLED (PRSEN = 1)
PWM Period
Shutdown Event
ECCPASE bit
PWM Activity
Normal PWM
Start of
PWM Period
DS41303G-page 184
Shutdown
Shutdown
Event Occurs Event Clears
PWM
Resumes
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.4.6
PROGRAMMABLE DEAD-BAND
DELAY MODE
FIGURE 16-12:
In Half-Bridge applications where all power switches
are modulated at the PWM frequency, the power
switches normally require more time to turn off than to
turn on. If both the upper and lower power switches are
switched at the same time (one turned on, and the
other turned off), both switches may be on for a short
period of time until one switch completely turns off.
During this brief interval, a very high current
(shoot-through current) will flow through both power
switches, shorting the bridge supply. To avoid this
potentially destructive shoot-through current from
flowing during switching, turning on either of the power
switches is normally delayed to allow the other switch
to completely turn off.
Period
Period
Pulse Width
P1A(2)
td
td
P1B(2)
(1)
(1)
(1)
td = Dead-Band Delay
Note 1:
In Half-Bridge mode, a digitally programmable
dead-band delay is available to avoid shoot-through
current from destroying the bridge power switches. The
delay occurs at the signal transition from the non-active
state to the active state. See Figure 16-12 for
illustration. The lower seven bits of the associated
PWM1CON register (Register 16-3) sets the delay
period in terms of microcontroller instruction cycles
(TCY or 4 TOSC).
FIGURE 16-13:
EXAMPLE OF
HALF-BRIDGE PWM
OUTPUT
2:
At this time, the TMR2 register is equal to the
PR2 register.
Output signals are shown as active-high.
EXAMPLE OF HALF-BRIDGE APPLICATIONS
V+
Standard Half-Bridge Circuit (“Push-Pull”)
FET
Driver
+
V
-
P1A
Load
FET
Driver
+
V
-
P1B
V-
 2010 Microchip Technology Inc.
DS41303G-page 185
PIC18F2XK20/4XK20
REGISTER 16-3:
PWM1CON: ENHANCED PWM CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
PRSEN
PDC6
PDC5
PDC4
PDC3
PDC2
PDC1
PDC0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
PRSEN: PWM Restart Enable bit
1 = Upon auto-shutdown, the ECCPASE bit clears automatically once the shutdown event goes
away; the PWM restarts automatically
0 = Upon auto-shutdown, ECCPASE must be cleared by software to restart the PWM
bit 6-0
PDC<6:0>: PWM Delay Count bits
PDCn = Number of FOSC/4 (4 * TOSC) cycles between the scheduled time when a PWM signal
should transition active and the actual time it transitions active
DS41303G-page 186
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.4.7
PULSE STEERING MODE
In Single Output mode, pulse steering allows any of the
PWM pins to be the modulated signal. Additionally, the
same PWM signal can be simultaneously available on
multiple pins.
Once the Single Output mode is selected
(CCP1M<3:2> = 11 and P1M<1:0> = 00 of the
CCP1CON register), the user firmware can bring out
the same PWM signal to one, two, three or four output
pins by setting the appropriate STR<D:A> bits of the
PSTRCON register, as shown in Table 16-1.
REGISTER 16-4:
Note:
The associated TRIS bits must be set to
output (‘0’) to enable the pin output driver
in order to see the PWM signal on the pin.
While the PWM Steering mode is active, CCP1M<1:0>
bits of the CCP1CON register select the PWM output
polarity for the P1<D:A> pins.
The PWM auto-shutdown operation also applies to
PWM Steering mode as described in Section 16.4.4
“Enhanced PWM Auto-shutdown mode”. An
auto-shutdown event will only affect pins that have
PWM outputs enabled.
PSTRCON: PULSE STEERING CONTROL REGISTER(1)
U-0
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-1
—
—
—
STRSYNC
STRD
STRC
STRB
STRA
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-5
Unimplemented: Read as ‘0’
bit 4
STRSYNC: Steering Sync bit
1 = Output steering update occurs on next PWM period
0 = Output steering update occurs at the beginning of the instruction cycle boundary
bit 3
STRD: Steering Enable bit D
1 = P1D pin has the PWM waveform with polarity control from CCPxM<1:0>
0 = P1D pin is assigned to port pin
bit 2
STRC: Steering Enable bit C
1 = P1C pin has the PWM waveform with polarity control from CCPxM<1:0>
0 = P1C pin is assigned to port pin
bit 1
STRB: Steering Enable bit B
1 = P1B pin has the PWM waveform with polarity control from CCPxM<1:0>
0 = P1B pin is assigned to port pin
bit 0
STRA: Steering Enable bit A
1 = P1A pin has the PWM waveform with polarity control from CCPxM<1:0>
0 = P1A pin is assigned to port pin
Note 1:
The PWM Steering mode is available only when the CCP1CON register bits CCP1M<3:2> = 11 and
P1M<1:0> = 00.
 2010 Microchip Technology Inc.
DS41303G-page 187
PIC18F2XK20/4XK20
FIGURE 16-14:
SIMPLIFIED STEERING
BLOCK DIAGRAM
STRA
P1A Signal
CCP1M1
1
PORT Data
0
P1A pin
STRB
CCP1M0
1
PORT Data
0
CCP1M1
1
PORT Data
0
P1C pin
TRIS
STRD
PORT Data
P1B pin
TRIS
STRC
CCP1M0
TRIS
P1D pin
1
0
TRIS
Note 1:
Port outputs are configured as shown when
the CCP1CON register bits P1M<1:0> = 00
and CCP1M<3:2> = 11.
2:
Single PWM output requires setting at least
one of the STRx bits.
DS41303G-page 188
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
16.4.7.1
Steering Synchronization
The STRSYNC bit of the PSTRCON register gives the
user two selections of when the steering event will
happen. When the STRSYNC bit is ‘0’, the steering
event will happen at the end of the instruction that
writes to the PSTRCON register. In this case, the
output signal at the P1<D:A> pins may be an
incomplete PWM waveform. This operation is useful
when the user firmware needs to immediately remove
a PWM signal from the pin.
Figures 16-15 and 16-16 illustrate the timing diagrams
of the PWM steering depending on the STRSYNC
setting.
When the STRSYNC bit is ‘1’, the effective steering
update will happen at the beginning of the next PWM
period. In this case, steering on/off the PWM output will
always produce a complete PWM waveform.
FIGURE 16-15:
EXAMPLE OF STEERING EVENT AT END OF INSTRUCTION (STRSYNC = 0)
PWM Period
PWM
STRn
P1<D:A>
PORT Data
PORT Data
P1n = PWM
FIGURE 16-16:
EXAMPLE OF STEERING EVENT AT BEGINNING OF INSTRUCTION
(STRSYNC = 1)
PWM
STRn
P1<D:A>
PORT Data
PORT Data
P1n = PWM
 2010 Microchip Technology Inc.
DS41303G-page 189
PIC18F2XK20/4XK20
16.4.8
OPERATION IN POWER-MANAGED
MODES
In Sleep mode, all clock sources are disabled. Timer2
will not increment and the state of the module will not
change. If the ECCP pin is driving a value, it will continue to drive that value. When the device wakes up, it
will continue from this state. If Two-Speed Start-ups are
enabled, the initial start-up frequency from HFINTOSC
and the postscaler may not be stable immediately.
In PRI_IDLE mode, the primary clock will continue to
clock the ECCP module without change. In all other
power-managed modes, the selected power-managed
mode clock will clock Timer2. Other power-managed
mode clocks will most likely be different than the
primary clock frequency.
16.4.8.1
Operation with Fail-Safe
Clock Monitor
If the Fail-Safe Clock Monitor is enabled, a clock failure
will force the device into the RC_RUN Power-Managed
mode and the OSCFIF bit of the PIR2 register will be
set. The ECCP will then be clocked from the internal
oscillator clock source, which may have a different
clock frequency than the primary clock.
See the previous section for additional details.
16.4.9
EFFECTS OF A RESET
Both Power-on Reset and subsequent Resets will force
all ports to Input mode and the CCP registers to their
Reset states.
This forces the enhanced CCP module to reset to a
state compatible with the standard CCP module.
DS41303G-page 190
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 16-2:
Name
INTCON
REGISTERS ASSOCIATED WITH ECCP1 MODULE AND TIMER1 TO TIMER3
Bit 7
Bit 6
GIE/GIEH PEIE/GIEL
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
RCON
IPEN
SBOREN
—
RI
TO
PD
POR
BOR
58
PIR1
PSPIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
TRISB
PORTB Data Direction Control Register
62
TRISC
PORTC Data Direction Control Register
62
TRISD
PORTD Data Direction Control Register
62
TMR1L
Timer1 Register, Low Byte
60
TMR1H
Timer1 Register, High Byte
60
T1CON
TMR2
T2CON
RD16
T1RUN
T1CKPS1
T1CKPS0
T1OSCEN
T1SYNC
TMR1CS
TMR1ON
Timer2 Register
—
60
60
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
60
PR2
Timer2 Period Register
60
TMR3L
Timer3 Register, Low Byte
61
TMR3H
Timer3 Register, High Byte
T3CON
RD16
T3CCP2
61
T3CKPS1
T3CKPS0
T3CCP1
T3SYNC
TMR3CS
TMR3ON
61
CCPR1L
Capture/Compare/PWM Register 1, Low Byte
61
CCPR1H
Capture/Compare/PWM Register 1, High Byte
61
CCP1CON
ECCP1AS
PWM1CON
Legend:
P1M1
P1M0
ECCPASE ECCPAS2
PRSEN
PDC6
DC1B1
DC1B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0
61
ECCPAS1
ECCPAS0
PSSAC1
PSSAC0
PSSBD1
PSSBD0
61
PDC5
PDC4
PDC3
PDC2
PDC1
PDC0
61
— = unimplemented, read as ‘0’. Shaded cells are not used during ECCP operation.
 2010 Microchip Technology Inc.
DS41303G-page 191
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 192
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.0
17.1
MASTER SYNCHRONOUS
SERIAL PORT (MSSP)
MODULE
Master SSP (MSSP) Module
Overview
The Master Synchronous Serial Port (MSSP) module is
a serial interface, useful for communicating with other
peripheral or microcontroller devices. These peripheral
devices may be serial EEPROMs, shift registers, display drivers, A/D converters, etc. The MSSP module
can operate in one of two modes:
• Serial Peripheral Interface (SPI)
• Inter-Integrated Circuit (I2C)
- Full Master mode
- Slave mode (with general address call)
17.3
SPI Mode
The SPI mode allows 8 bits of data to be synchronously
transmitted and received simultaneously. All four
modes of SPI are supported. To accomplish
communication, typically three pins are used:
• Serial Data Out – SDO
• Serial Data In – SDI/SDA
• Serial Clock – SCK/SCL
Additionally, a fourth pin may be used when in a Slave
mode of operation:
• Slave Select – SS
Figure 17-1 shows the block diagram of the MSSP
module when operating in SPI mode.
FIGURE 17-1:
MSSP BLOCK DIAGRAM
(SPI MODE)
The I2C interface supports the following modes in
hardware:
Internal
Data Bus
Read
• Master mode
• Multi-Master mode
• Slave mode
17.2
Control Registers
The MSSP module has seven associated registers.
These include:
•
•
•
•
•
•
•
SSPSTA – STATUS register
SSPCON1 – First Control register
SSPCON2 – Second Control register
SSPBUF – Transmit/Receive buffer
SSPSR – Shift register (not directly accessible)
SSPADD – Address register
SSPMSK – Address Mask register
Write
SSPBUF Reg
SDI/SDA
SSPSR Reg
Shift
Clock
SDO
bit 0
SS
SS Control
Enable
Edge
Select
The use of these registers and their individual Configuration bits differ significantly depending on whether the
MSSP module is operated in SPI or I2C mode.
2
Clock Select
Additional details are provided under the individual
sections.
SCK/SCL
SSPM<3:0>
SMP:CKE 4
TMR2 Output
2
2
(
Edge
Select
)
Prescaler TOSC
4, 16, 64
Data to TX/RX in SSPSR
TRIS bit
 2010 Microchip Technology Inc.
DS41303G-page 193
PIC18F2XK20/4XK20
17.3.1
REGISTERS
SSPSR is the shift register used for shifting data in
and out. SSPBUF provides indirect access to the
SSPSR register. SSPBUF is the buffer register to
which data bytes are written, and from which data
bytes are read.
The MSSP module has four registers for SPI mode
operation. These are:
•
•
•
•
SSPCON1 – Control Register
SSPSTAT – STATUS register
SSPBUF – Serial Receive/Transmit Buffer
SSPSR – Shift Register (Not directly accessible)
In receive operations, SSPSR and SSPBUF together
create a double-buffered receiver. When SSPSR
receives a complete byte, it is transferred to SSPBUF
and the SSPIF interrupt is set.
SSPCON1 and SSPSTAT are the control and STATUS registers in SPI mode operation. The SSPCON1
register is readable and writable. The lower 6 bits of
the SSPSTAT are read-only. The upper two bits of the
SSPSTAT are read/write.
REGISTER 17-1:
During
transmission,
the
SSPBUF
is
not
double-buffered. A write to SSPBUF will write to both
SSPBUF and SSPSR.
SSPSTAT: MSSP STATUS REGISTER (SPI MODE)
R/W-0
R/W-0
R-0
R-0
R-0
R-0
R-0
R-0
SMP
CKE
D/A
P
S
R/W
UA
BF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
SMP: Sample bit
SPI Master mode:
1 = Input data sampled at end of data output time
0 = Input data sampled at middle of data output time
SPI Slave mode:
SMP must be cleared when SPI is used in Slave mode.
bit 6
CKE: SPI Clock Select bit(1)
1 = Output data changes on clock transition from active to idle
0 = Output data changes on clock transition from idle to active
bit 5
D/A: Data/Address bit
Used in I2C mode only.
bit 4
P: Stop bit
Used in I2C mode only. This bit is cleared when the MSSP module is disabled, SSPEN is cleared.
bit 3
S: Start bit
Used in I2C mode only.
bit 2
R/W: Read/Write Information bit
Used in I2C mode only.
bit 1
UA: Update Address bit
Used in I2C mode only.
bit 0
BF: Buffer Full Status bit (Receive mode only)
1 = Receive complete, SSPBUF is full
0 = Receive not complete, SSPBUF is empty
Note 1:
Polarity of clock state is set by the CKP bit of the SSPCON1 register.
DS41303G-page 194
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 17-2:
SSPCON1: MSSP CONTROL 1 REGISTER (SPI MODE)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
WCOL: Write Collision Detect bit (Transmit mode only)
1 = The SSPBUF register is written while it is still transmitting the previous word
(must be cleared by software)
0 = No collision
bit 6
SSPOV: Receive Overflow Indicator bit(1)
SPI Slave mode:
1 = A new byte is received while the SSPBUF register is still holding the previous data. In case of overflow, the data in SSPSR is lost. Overflow can only occur in Slave mode. The user must read the
SSPBUF, even if only transmitting data, to avoid setting overflow (must be cleared by software).
0 = No overflow
bit 5
SSPEN: Synchronous Serial Port Enable bit(2)
1 = Enables serial port and configures SCK, SDO, SDI and SS as serial port pins. When enabled, the
SDA and SCL pins must be configured as inputs.
0 = Disables serial port and configures these pins as I/O port pins
bit 4
CKP: Clock Polarity Select bit
1 = Idle state for clock is a high level
0 = Idle state for clock is a low level
bit 3-0
SSPM<3:0>: Synchronous Serial Port Mode Select bits(3)
0101 = SPI Slave mode, clock = SCK pin, SS pin control disabled, SS can be used as I/O pin
0100 = SPI Slave mode, clock = SCK pin, SS pin control enabled
0011 = SPI Master mode, clock = TMR2 output/2
0010 = SPI Master mode, clock = FOSC/64
0001 = SPI Master mode, clock = FOSC/16
0000 = SPI Master mode, clock = FOSC/4
Note 1:
2:
3:
In Master mode, the overflow bit is not set since each new reception (and transmission) is initiated by
writing to the SSPBUF register.
When enabled, these pins must be properly configured as input or output.
Bit combinations not specifically listed here are either reserved or implemented in I2C mode only.
 2010 Microchip Technology Inc.
DS41303G-page 195
PIC18F2XK20/4XK20
17.3.2
OPERATION
When initializing the SPI, several options need to be
specified. This is done by programming the appropriate
control bits (SSPCON1<5:0> and SSPSTAT<7:6>).
These control bits allow the following to be specified:
•
•
•
•
Master mode (SCK is the clock output)
Slave mode (SCK is the clock input)
Clock Polarity (Idle state of SCK)
Data Input Sample Phase (middle or end of data
output time)
• Clock Edge (output data on rising/falling edge of
SCK)
• Clock Rate (Master mode only)
• Slave Select mode (Slave mode only)
The MSSP consists of a transmit/receive shift register
(SSPSR) and a buffer register (SSPBUF). The SSPSR
shifts the data in and out of the device, MSb first. The
SSPBUF holds the data that was written to the SSPSR
until the received data is ready. Once the 8 bits of data
have been received, that byte is moved to the SSPBUF
register. Then, the Buffer Full detect bit, BF of the
SSPSTAT register, and the interrupt flag bit, SSPIF, are
set. This double-buffering of the received data
(SSPBUF) allows the next byte to start reception before
reading the data that was just received. Any write to the
SSPBUF register during transmission/reception of data
will be ignored and the write collision detect bit WCOL
of the SSPCON1 register, will be set. User software
must clear the WCOL bit so that it can be determined if
the following write(s) to the SSPBUF register
completed successfully.
EXAMPLE 17-1:
LOOP
When the application software is expecting to receive
valid data, the SSPBUF should be read before the next
byte of data to transfer is written to the SSPBUF. The
Buffer Full bit, BF of the SSPSTAT register, indicates
when SSPBUF has been loaded with the received data
(transmission is complete). When the SSPBUF is read,
the BF bit is cleared. This data may be irrelevant if the
SPI is only a transmitter. Generally, the MSSP interrupt
is used to determine when the transmission/reception
has completed. The SSPBUF must be read and/or
written. If the interrupt method is not going to be used,
then software polling can be done to ensure that a write
collision does not occur. Example 17-1 shows the
loading of the SSPBUF (SSPSR) for data transmission.
The SSPSR is not directly readable or writable and can
only be accessed by addressing the SSPBUF register.
Additionally, the MSSP STATUS register (SSPSTAT)
indicates the various status conditions.
LOADING THE SSPBUF (SSPSR) REGISTER
BTFSS
BRA
MOVF
SSPSTAT, BF
LOOP
SSPBUF, W
;Has data been received (transmit complete)?
;No
;WREG reg = contents of SSPBUF
MOVWF
RXDATA
;Save in user RAM, if data is meaningful
MOVF
MOVWF
TXDATA, W
SSPBUF
;W reg = contents of TXDATA
;New data to xmit
DS41303G-page 196
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.3.3
ENABLING SPI I/O
17.3.4
To enable the serial port, SSP Enable bit, SSPEN of
the SSPCON1 register, must be set. To reset or reconfigure SPI mode, clear the SSPEN bit, reinitialize the
SSPCON registers and then set the SSPEN bit. This
configures the SDI, SDO, SCK and SS pins as serial
port pins. For the pins to behave as the serial port function, some must have their data direction bits (in the
TRIS register) appropriately programmed as follows:
• SDI is automatically controlled by the SPI module
• SDO must have corresponding TRIS bit cleared
• SCK (Master mode) must have corresponding
TRIS bit cleared
• SCK (Slave mode) must have corresponding
TRIS bit set
• SS must have corresponding TRIS bit set
TYPICAL CONNECTION
Figure 17-2 shows a typical connection between two
microcontrollers. The master controller (Processor 1)
initiates the data transfer by sending the SCK signal.
Data is shifted out of both shift registers on their programmed clock edge and latched on the opposite edge
of the clock. Both processors should be programmed to
the same Clock Polarity (CKP), then both controllers
would send and receive data at the same time.
Whether the data is meaningful (or dummy data)
depends on the application software. This leads to
three scenarios for data transmission:
• Master sends data–Slave sends dummy data
• Master sends data–Slave sends data
• Master sends dummy data–Slave sends data
Any serial port function that is not desired may be
overridden by programming the corresponding data
direction (TRIS) register to the opposite value.
FIGURE 17-2:
SPI MASTER/SLAVE CONNECTION
SPI Master SSPM<3:0> = 00xxb
SPI Slave SSPM<3:0> = 010xb
SDO
SDI
Serial Input Buffer
(SSPBUF)
SDI
Shift Register
(SSPSR)
MSb
Serial Input Buffer
(SSPBUF)
LSb
 2010 Microchip Technology Inc.
Shift Register
(SSPSR)
MSb
SCK
Processor 1
SDO
Serial Clock
LSb
SCK
Processor 2
DS41303G-page 197
PIC18F2XK20/4XK20
17.3.5
MASTER MODE
The master can initiate the data transfer at any time
because it controls the SCK. The master determines
when the slave (Processor 2, Figure 17-2) is to
broadcast data by the software protocol.
In Master mode, the data is transmitted/received as
soon as the SSPBUF register is written to. If the SPI is
only going to receive, the SDO output could be disabled (programmed as an input). The SSPSR register
will continue to shift in the signal present on the SDI pin
at the programmed clock rate. As each byte is
received, it will be loaded into the SSPBUF register as
if a normal received byte (interrupts and Status bits
appropriately set). This could be useful in receiver
applications as a “Line Activity Monitor” mode.
FIGURE 17-3:
The clock polarity is selected by appropriately
programming the CKP bit of the SSPCON1 register.
This then, would give waveforms for SPI
communication as shown in Figure 17-3, Figure 17-5
and Figure 17-6, where the MSB is transmitted first. In
Master mode, the SPI clock rate (bit rate) is user
programmable to be one of the following:
•
•
•
•
FOSC/4 (or TCY)
FOSC/16 (or 4 • TCY)
FOSC/64 (or 16 • TCY)
Timer2 output/2
This allows a maximum data rate (at 64 MHz) of
16.00 Mbps.
Figure 17-3 shows the waveforms for Master mode.
When the CKE bit is set, the SDO data is valid before
there is a clock edge on SCK. The change of the input
sample is shown based on the state of the SMP bit. The
time when the SSPBUF is loaded with the received
data is shown.
SPI MODE WAVEFORM (MASTER MODE)
Write to
SSPBUF
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
4 Clock
Modes
SCK
(CKP = 0
CKE = 1)
SCK
(CKP = 1
CKE = 1)
SDO
(CKE = 0)
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
SDO
(CKE = 1)
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
SDI
(SMP = 0)
bit 0
bit 7
Input
Sample
(SMP = 0)
SDI
(SMP = 1)
bit 7
bit 0
Input
Sample
(SMP = 1)
SSPIF
SSPSR to
SSPBUF
DS41303G-page 198
Next Q4 Cycle
after Q2
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.3.6
SLAVE MODE
In Slave mode, the data is transmitted and received as
the external clock pulses appear on SCK. When the
last bit is latched, the SSPIF interrupt flag bit is set.
Before enabling the module in SPI Slave mode, the clock
line must match the proper Idle state. The clock line can
be observed by reading the SCK pin. The Idle state is
determined by the CKP bit of the SSPCON1 register.
While in Slave mode, the external clock is supplied by
the external clock source on the SCK pin. This external
clock must meet the minimum high and low times as
specified in the electrical specifications.
While in Sleep mode, the slave can transmit/receive
data. When a byte is received, the device will wake-up
from Sleep.
17.3.7
SLAVE SELECT
SYNCHRONIZATION
The SS pin allows a Synchronous Slave mode. The
SPI must be in Slave mode with SS pin control enabled
(SSPCON1<3:0> = 04h). The pin must not be driven
low for the SS pin to function as an input. The data latch
FIGURE 17-4:
must be high. When the SS pin is low, transmission and
reception are enabled and the SDO pin is driven. When
the SS pin goes high, the SDO pin is no longer driven,
even if in the middle of a transmitted byte and becomes
a floating output. External pull-up/pull-down resistors
may be desirable depending on the application.
Note 1: When the SPI is in Slave mode with SS pin
control enabled (SSPCON<3:0> = 0100),
the SPI module will reset if the SS pin is set
to VDD.
2: When the SPI is used in Slave mode with
CKE set the SS pin control must also be
enabled.
When the SPI module resets, the bit counter is forced
to ‘0’. This can be done by either forcing the SS pin to
a high level or clearing the SSPEN bit.
To emulate two-wire communication, the SDO pin can
be connected to the SDI pin. When the SPI needs to
operate as a receiver, the SDO pin can be configured
as an input. This disables transmissions from the SDO.
The SDI can always be left as an input (SDI function)
since it cannot create a bus conflict.
SLAVE SYNCHRONIZATION WAVEFORM
SS
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
Write to
SSPBUF
SDO
SDI
(SMP = 0)
bit 7
bit 6
bit 7
bit 0
bit 0
bit 7
bit 7
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
SSPSR to
SSPBUF
 2010 Microchip Technology Inc.
Next Q4 Cycle
after Q2
DS41303G-page 199
PIC18F2XK20/4XK20
FIGURE 17-5:
SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 0)
SS
Optional
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
Write to
SSPBUF
SDO
SDI
(SMP = 0)
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
bit 0
bit 7
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
Next Q4 Cycle
after Q2
SSPSR to
SSPBUF
FIGURE 17-6:
SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 1)
SS
Not Optional
SCK
(CKP = 0
CKE = 1)
SCK
(CKP = 1
CKE = 1)
Write to
SSPBUF
SDO
bit 7
SDI
(SMP = 0)
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
bit 0
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
SSPSR to
SSPBUF
DS41303G-page 200
Next Q4 Cycle
after Q2
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.3.8
OPERATION IN POWER-MANAGED
MODES
Transmit/Receive Shift register. When all 8 bits have
been received, the MSSP interrupt flag bit will be set
and if enabled, will wake the device.
In SPI Master mode, module clocks may be operating
at a different speed than when in full power mode; in
the case of the Sleep mode, all clocks are halted.
17.3.9
In all Idle modes, a clock is provided to the peripherals.
That clock could be from the primary clock source, the
secondary clock (Timer1 oscillator at 32.768 kHz) or
the INTOSC source. See Section 3.0 “Power-Managed Modes” for additional information.
17.3.10
In most cases, the speed that the master clocks SPI
data is not important; however, this should be
evaluated for each system.
When MSSP interrupts are enabled, after the master
completes sending data, an MSSP interrupt will wake
the controller:
EFFECTS OF A RESET
A Reset disables the MSSP module and terminates the
current transfer.
BUS MODE COMPATIBILITY
Table 17-1 shows the compatibility between the
standard SPI modes and the states of the CKP and
CKE control bits.
TABLE 17-1:
SPI BUS MODES
Control Bits State
Standard SPI Mode
Terminology
CKP
CKE
• from Sleep, in slave mode
• from Idle, in slave or master mode
0, 0
0
1
0, 1
0
0
If an exit from Sleep or Idle mode is not desired, MSSP
interrupts should be disabled.
1, 0
1
1
1, 1
1
0
In SPI master mode, when the Sleep mode is selected,
all module clocks are halted and the transmission/reception will remain in that state until the devices
wakes. After the device returns to Run mode, the module will resume transmitting and receiving data.
There is also an SMP bit which controls when the data
is sampled.
In SPI Slave mode, the SPI Transmit/Receive Shift
register operates asynchronously to the device. This
allows the device to be placed in any power-managed
mode and data to be shifted into the SPI
TABLE 17-2:
Name
INTCON
REGISTERS ASSOCIATED WITH SPI OPERATION
Bit 7
Bit 6
Bit 5
GIE/GIEH PEIE/GIEL TMR0IE
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF
(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
62
TRISA
TRISA7(2) TRISA6(2)
TRISC
SSPBUF
TRISC7
TRISC6
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
TRISA5
TRISA4
TRISA3
TRISA2
TRISA1
TRISA0
62
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
62
SSP Receive Buffer/Transmit Register
60
SSPCON1
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
60
SSPSTAT
SMP
CKE
D/A
P
S
R/W
UA
BF
60
Legend: Shaded cells are not used by the MSSP in SPI mode.
Note 1: These bits are unimplemented in 28-pin devices; always maintain these bits clear.
2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary
oscillator modes. When disabled, these bits read as ‘0’.
 2010 Microchip Technology Inc.
DS41303G-page 201
PIC18F2XK20/4XK20
17.4
I2C Mode
17.4.1
The MSSP module in I 2C mode fully implements all
master and slave functions (including general call
support) and provides interrupts on Start and Stop bits
in hardware to determine a free bus (multi-master
function). The MSSP module implements the standard
mode specifications as well as 7-bit and 10-bit
addressing.
Two pins are used for data transfer:
• Serial clock (SCL) – SCK/SCL
• Serial data (SDA) – SDI/SDA
The user must configure these pins as inputs with the
corresponding TRIS bits.
FIGURE 17-7:
MSSP BLOCK DIAGRAM
(I2C™ MODE)
Internal
Data Bus
Read
Write
Shift
Clock
SSPSR Reg
SDI/SDA
MSb
LSb
SSPMSK Reg
Match Detect
Addr Match
SSPADD Reg
Start and
Stop bit Detect
DS41303G-page 202
The MSSP module has seven registers for I2C
operation. These are:
•
•
•
•
MSSP Control Register 1 (SSPCON1)
MSSP Control Register 2 (SSPCON2)
MSSP STATUS register (SSPSTAT)
Serial Receive/Transmit Buffer Register
(SSPBUF)
• MSSP Shift Register (SSPSR) – Not directly
accessible
• MSSP Address Register (SSPADD)
• MSSP Address Mask (SSPMSK)
SSPCON1, SSPCON2 and SSPSTAT are the control
and STATUS registers in I2C mode operation. The
SSPCON1 and SSPCON2 registers are readable and
writable. The lower 6 bits of the SSPSTAT are read-only.
The upper two bits of the SSPSTAT are read/write.
SSPSR is the shift register used for shifting data in or
out. SSPBUF is the buffer register to which data bytes
are written to or read from.
When the SSP is configured in Master mode, the lower
seven bits of SSPADD act as the Baud Rate Generator
reload value. When the SSP is configured for I2C slave
mode the SSPADD register holds the slave device
address. The SSP can be configured to respond to a
range of addresses by qualifying selected bits of the
address register with the SSPMSK register.
SSPBUF Reg
SCK/SCL
REGISTERS
Set, Reset
S, P bits
(SSPSTAT Reg)
In receive operations, SSPSR and SSPBUF together
create a double-buffered receiver. When SSPSR
receives a complete byte, it is transferred to SSPBUF
and the SSPIF interrupt is set.
During
transmission,
the
SSPBUF
is
not
double-buffered. A write to SSPBUF will write to both
SSPBUF and SSPSR.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 17-3:
SSPADD: MSSP ADDRESS AND BAUD RATE REGISTER (I2C MODE)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ADD7
ADD6
ADD5
ADD4
ADD3
ADD2
ADD1
ADD0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
Master mode
bit 7-0
ADD<7:0>: Baud Rate Clock Divider bits
SCL pin clock period = ((ADD<7:0> + 1) *4)/FOSC
10-Bit Slave mode: Most significant address byte
bit 7-3
Not used: Unused for most significant address byte. Bit state of this register is a don’t care. Bit pattern
sent by master is fixed by I2C specification and must be equal to ‘11110’. However, those bits are
compared by hardware and are not affected by the value in this register.
bit 2-1
ADD<9:8>: Two most significant bits of 10-bit address
bit 0
Not used: Unused in this mode. Bit state is a “don’t care”.
10-Bit Slave mode: Least significant address byte
bit 7-0
ADD<7:0>: Eight least significant bits of 10-bit address
7-Bit Slave mode
bit 7-1
ADD<7:1>: 7-bit address
bit 0
Not used: Unused in this mode. Bit state is a “don’t care”.
 2010 Microchip Technology Inc.
DS41303G-page 203
PIC18F2XK20/4XK20
REGISTER 17-4:
R/W-0
SSPSTAT: MSSP STATUS REGISTER (I2C MODE)
R/W-0
SMP
CKE
R-0
R-0
R-0
D/A
(1)
(1)
P
S
R-0
R/W
(2, 3)
R-0
R-0
UA
BF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
SMP: Slew Rate Control bit
In Master or Slave mode:
1 = Slew rate control disabled for standard speed mode (100 kHz and 1 MHz)
0 = Slew rate control enabled for high-speed mode (400 kHz)
bit 6
CKE: SMBus Select bit
In Master or Slave mode:
1 = Enable SMBus specific inputs
0 = Disable SMBus specific inputs
bit 5
D/A: Data/Address bit
In Master mode:
Reserved.
In Slave mode:
1 = Indicates that the last byte received or transmitted was data
0 = Indicates that the last byte received or transmitted was address
bit 4
P: Stop bit(1)
1 = Indicates that a Stop bit has been detected last
0 = Stop bit was not detected last
bit 3
S: Start bit(1)
1 = Indicates that a Start bit has been detected last
0 = Start bit was not detected last
bit 2
R/W: Read/Write Information bit (I2C mode only)(2, 3)
In Slave mode:
1 = Read
0 = Write
In Master mode:
1 = Transmit is in progress
0 = Transmit is not in progress
bit 1
UA: Update Address bit (10-bit Slave mode only)
1 = Indicates that the user needs to update the address in the SSPADD register
0 = Address does not need to be updated
bit 0
BF: Buffer Full Status bit
In Transmit mode:
1 = SSPBUF is full
0 = SSPBUF is empty
In Receive mode:
1 = SSPBUF is full (does not include the ACK and Stop bits)
0 = SSPBUF is empty (does not include the ACK and Stop bits)
Note 1:
2:
3:
This bit is cleared on Reset and when SSPEN is cleared.
This bit holds the R/W bit information following the last address match. This bit is only valid from the
address match to the next Start bit, Stop bit or not ACK bit.
ORing this bit with SEN, RSEN, PEN, RCEN or ACKEN will indicate if the MSSP is in Active mode.
DS41303G-page 204
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 17-5:
SSPCON1: MSSP CONTROL 1 REGISTER (I2C MODE)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
WCOL: Write Collision Detect bit
In Master Transmit mode:
1 = A write to the SSPBUF register was attempted while the I2C conditions were not valid for a transmission to be started (must be cleared by software)
0 = No collision
In Slave Transmit mode:
1 = The SSPBUF register is written while it is still transmitting the previous word (must be cleared by
software)
0 = No collision
In Receive mode (Master or Slave modes):
This is a “don’t care” bit.
bit 6
SSPOV: Receive Overflow Indicator bit
In Receive mode:
1 = A byte is received while the SSPBUF register is still holding the previous byte (must be cleared
by software)
0 = No overflow
In Transmit mode:
This is a “don’t care” bit in Transmit mode.
bit 5
SSPEN: Synchronous Serial Port Enable bit
1 = Enables the serial port and configures the SDA and SCL pins as the serial port pins. When
enabled, the SDA and SCL pins must be configured as inputs.
0 = Disables serial port and configures these pins as I/O port pins
bit 4
CKP: SCK Release Control bit
In Slave mode:
1 = Release clock
0 = Holds clock low (clock stretch), used to ensure data setup time
In Master mode:
Unused in this mode.
bit 3-0
SSPM<3:0>: Synchronous Serial Port Mode Select bits
1111 = I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled
1110 = I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled
1011 = I2C Firmware Controlled Master mode (Slave Idle)
1000 = I2C Master mode, clock = FOSC/(4 * (SSPADD + 1))
0111 = I2C Slave mode, 10-bit address
0110 = I2C Slave mode, 7-bit address
Bit combinations not specifically listed here are either reserved or implemented in SPI mode only.
 2010 Microchip Technology Inc.
DS41303G-page 205
PIC18F2XK20/4XK20
REGISTER 17-6:
R/W-0
SSPCON2: MSSP CONTROL REGISTER (I2C MODE)
R/W-0
GCEN
ACKSTAT
R/W-0
(2)
ACKDT
R/W-0
(1)
ACKEN
R/W-0
(1)
RCEN
R/W-0
(1)
PEN
R/W-0
(1)
RSEN
R/W-0
SEN(1)
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
GCEN: General Call Enable bit (Slave mode only)
1 = Generate interrupt when a general call address (0000h) is received in the SSPSR
0 = General call address disabled
bit 6
ACKSTAT: Acknowledge Status bit (Master Transmit mode only)
1 = Acknowledge was not received from slave
0 = Acknowledge was received from slave
bit 5
ACKDT: Acknowledge Data bit (Master Receive mode only)(2)
1 = Not Acknowledge
0 = Acknowledge
bit 4
ACKEN: Acknowledge Sequence Enable bit (Master Receive mode only)(1)
1 = Initiate Acknowledge sequence on SDA and SCL pins and transmit ACKDT data bit.
Automatically cleared by hardware.
0 = Acknowledge sequence Idle
bit 3
RCEN: Receive Enable bit (Master mode only)(1)
1 = Enables Receive mode for I2C
0 = Receive Idle
bit 2
PEN: Stop Condition Enable bit (Master mode only)(1)
1 = Initiate Stop condition on SDA and SCL pins. Automatically cleared by hardware.
0 = Stop condition Idle
bit 1
RSEN: Repeated Start Condition Enable bit (Master mode only)(1)
1 = Initiate Repeated Start condition on SDA and SCL pins. Automatically cleared by hardware.
0 = Repeated Start condition Idle
bit 0
SEN: Start Condition Enable/Stretch Enable bit(1)
In Master mode:
1 = Initiate Start condition on SDA and SCL pins. Automatically cleared by hardware.
0 = Start condition Idle
In Slave mode:
1 = Clock stretching is enabled for both slave transmit and slave receive (stretch enabled)
0 = Clock stretching is disabled for slave received. Slave transmit clock stretching remains enabled.
Note 1:
2:
For bits ACKEN, RCEN, PEN, RSEN, SEN: If the I2C module is not in the Idle mode, these bits may not
be set (no spooling) and the SSPBUF may not be written (or writes to the SSPBUF are disabled).
Value that will be transmitted when the user initiates an Acknowledge sequence at the end of a receive.
DS41303G-page 206
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.2
OPERATION
The MSSP module functions are enabled by setting
SSPEN bit of the SSPCON1 register.
The SSPCON1 register allows control of the I 2C
operation. Four mode selection bits of the SSPCON1
register allow one of the following I 2C modes to be
selected:
• I2C Master mode, clock = (FOSC/(4 x
(SSPADD + 1))
• I 2C Slave mode (7-bit address)
• I 2C Slave mode (10-bit address)
• I 2C Slave mode (7-bit address) with Start and
Stop bit interrupts enabled
• I 2C Slave mode (10-bit address) with Start and
Stop bit interrupts enabled
• I 2C Firmware Controlled Master mode, slave is
Idle
Selection of any I 2C mode with the SSPEN bit set,
forces the SCL and SDA pins to be open-drain,
provided these pins are programmed to inputs by
setting the appropriate TRIS bits. To ensure proper
operation of the module, pull-up resistors must be
provided externally to the SCL and SDA pins.
17.4.3
SLAVE MODE
In Slave mode, the SCL and SDA pins must be configured as inputs. The MSSP module will override the
input state with the output data when required
(slave-transmitter).
The I 2C Slave mode hardware will always generate an
interrupt on an address match. Through the mode
select bits, the user can also choose to interrupt on
Start and Stop bits
When an address is matched, or the data transfer after
an address match is received, the hardware
automatically will generate the Acknowledge (ACK)
pulse and load the SSPBUF register with the received
value currently in the SSPSR register.
17.4.3.1
Once the MSSP module has been enabled, it waits for
a Start condition to occur. Following the Start condition,
the 8 bits are shifted into the SSPSR register. All
incoming bits are sampled with the rising edge of the
clock (SCL) line. The value of register SSPSR<7:1> is
compared to the value of the SSPADD register. The
address is compared on the falling edge of the eighth
clock (SCL) pulse. If the addresses match and the BF
and SSPOV bits are clear, the following events occur:
1.
2.
3.
4.
In this case, the SSPSR register value is not loaded
into the SSPBUF, but bit SSPIF of the PIR1 register is
set. The BF bit is cleared by reading the SSPBUF
register, while bit SSPOV is cleared through software.
The SSPSR register value is loaded into the
SSPBUF register.
The Buffer Full bit, BF, is set.
An ACK pulse is generated.
MSSP Interrupt Flag bit, SSPIF of the PIR1 register, is set (interrupt is generated, if enabled) on
the falling edge of the ninth SCL pulse.
In 10-bit Address mode, two address bytes need to be
received by the slave. The five Most Significant bits
(MSbs) of the first address byte specify if this is a 10-bit
address. Bit R/W of the SSPSTAT register must specify
a write so the slave device will receive the second
address byte. For a 10-bit address, the first byte would
equal ‘11110 A9 A8 0’, where ‘A9’ and ‘A8’ are the two
MSbs of the address. The sequence of events for 10-bit
address is as follows, with steps 7 through 9 for the
slave-transmitter:
1.
2.
3.
4.
5.
Any combination of the following conditions will cause
the MSSP module not to give this ACK pulse:
• The Buffer Full bit, BF bit of the SSPSTAT register, is set before the transfer is received.
• The overflow bit, SSPOV bit of the SSPCON1
register, is set before the transfer is received.
Addressing
6.
7.
8.
9.
Receive first (high) byte of address (bits SSPIF,
BF and UA (of the SSPSTAT register are set).
Update the SSPADD register with second (low)
byte of address (clears bit UA and releases the
SCL line).
Read the SSPBUF register (clears bit BF) and
clear flag bit, SSPIF.
Receive second (low) byte of address (bits
SSPIF, BF and UA are set). If the address
matches then the SCL is held until the next step.
Otherwise the SCL line is not held.
Update the SSPADD register with the first (high)
byte of address. (This will clear bit UA and
release a held SCL line.)
Read the SSPBUF register (clears bit BF) and
clear flag bit, SSPIF.
Receive Repeated Start condition.
Receive first (high) byte of address (bits SSPIF
and BF are set).
Read the SSPBUF register (clears bit BF) and
clear flag bit, SSPIF.
The SCL clock input must have a minimum high and
low for proper operation. The high and low times of the
I2C specification, as well as the requirement of the
MSSP module, are shown in timing parameter 100 and
parameter 101 (See Table 26-19).
 2010 Microchip Technology Inc.
DS41303G-page 207
PIC18F2XK20/4XK20
17.4.3.2
Reception
When the R/W bit of the address byte is clear and an
address match occurs, the R/W bit of the SSPSTAT
register is cleared. The received address is loaded into
the SSPBUF register and the SDA line is held low
(ACK).
When the address byte overflow condition exists, then
the no Acknowledge (ACK) pulse is given. An overflow
condition is defined as either bit BF bit of the SSPSTAT
register is set, or bit SSPOV bit of the SSPCON1
register is set.
An MSSP interrupt is generated for each data transfer
byte. Flag bit, SSPIF of the PIR1 register, must be
cleared by software. The SSPSTAT register is used to
determine the status of the byte.
When the SEN bit of the SSPCON2 register is set,
SCK/SCL will be held low (clock stretch) following
each data transfer. The clock must be released by
setting the CKP bit of the SSPCON1 register. See
Section 17.4.4 “Clock Stretching” for more detail.
17.4.3.3
Transmission
When the R/W bit of the incoming address byte is set
and an address match occurs, the R/W bit of the
SSPSTAT register is set. The received address is
loaded into the SSPBUF register. The ACK pulse will
be sent on the ninth bit and pin SCK/SCL is held low
regardless of SEN (see Section 17.4.4 “Clock
Stretching” for more detail). By stretching the clock,
the master will be unable to assert another clock pulse
until the slave is done preparing the transmit data. The
transmit data must be loaded into the SSPBUF register
which also loads the SSPSR register. Then pin
SCK/SCL should be enabled by setting the CKP bit of
the SSPCON1 register. The eight data bits are shifted
out on the falling edge of the SCL input. This ensures
that the SDA signal is valid during the SCL high time
(Figure 17-9).
The ACK pulse from the master-receiver is latched on
the rising edge of the ninth SCL input pulse. If the SDA
line is high (not ACK), then the data transfer is
complete. In this case, when the ACK is latched by the
slave, the slave logic is reset (resets SSPSTAT
register) and the slave monitors for another occurrence
of the Start bit. If the SDA line was low (ACK), the next
transmit data must be loaded into the SSPBUF register.
Again, pin SCK/SCL must be enabled by setting bit
CKP.
An MSSP interrupt is generated for each data transfer
byte. The SSPIF bit must be cleared by software and
the SSPSTAT register is used to determine the status
of the byte. The SSPIF bit is set on the falling edge of
the ninth clock pulse.
DS41303G-page 208
 2010 Microchip Technology Inc.
 2010 Microchip Technology Inc.
CKP
2
A6
3
4
A4
5
A3
Receiving Address
A5
6
A2
(CKP does not reset to ‘0’ when SEN = 0)
SSPOV (SSPCON1<6>)
BF (SSPSTAT<0>)
(PIR1<3>)
SSPIF
1
SCL
S
A7
7
A1
8
9
ACK
R/W = 0
1
D7
3
4
D4
5
D3
Receiving Data
D5
Cleared by software
SSPBUF is read
2
D6
6
D2
7
D1
8
D0
9
ACK
1
D7
2
D6
3
4
D4
5
D3
Receiving Data
D5
6
D2
7
D1
8
D0
Bus master
terminates
transfer
P
SSPOV is set
because SSPBUF is
still full. ACK is not sent.
9
ACK
FIGURE 17-8:
SDA
PIC18F2XK20/4XK20
I2C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 7-BIT ADDRESS)
DS41303G-page 209
DS41303G-page 210
1
CKP
2
A6
Data in
sampled
BF (SSPSTAT<0>)
SSPIF (PIR1<3>)
S
A7
3
4
A4
5
A3
6
A2
Receiving Address
A5
7
A1
8
R/W = 0
9
ACK
SCL held low
while CPU
responds to SSPIF
1
D7
3
D5
4
5
D3
CKP is set by software
SSPBUF is written by software
6
D2
Transmitting Data
D4
Cleared by software
2
D6
7
8
D0
9
From SSPIF ISR
D1
ACK
1
D7
4
D4
5
D3
Cleared by software
3
D5
6
D2
CKP is set by software
SSPBUF is written by software
2
D6
7
8
D0
9
ACK
From SSPIF ISR
D1
Transmitting Data
P
FIGURE 17-9:
SCL
SDA
PIC18F2XK20/4XK20
I2C™ SLAVE MODE TIMING (TRANSMISSION, 7-BIT ADDRESS)
 2010 Microchip Technology Inc.
 2010 Microchip Technology Inc.
2
1
4
1
5
0
7
A8
UA is set indicating that
the SSPADD needs to be
updated
SSPBUF is written with
contents of SSPSR
6
A9
8
9
(CKP does not reset to ‘0’ when SEN = 0)
UA (SSPSTAT<1>)
SSPOV (SSPCON1<6>)
CKP
3
1
Cleared by software
BF (SSPSTAT<0>)
(PIR1<3>)
SSPIF
1
SCL
S
1
ACK
R/W = 0
A7
2
4
A4
5
A3
6
A2
8
9
A0 ACK
UA is set indicating that
SSPADD needs to be
updated
Cleared by hardware
when SSPADD is updated
with low byte of address
7
A1
Cleared by software
3
A5
Dummy read of SSPBUF
to clear BF flag
1
A6
Receive Second Byte of Address
1
D7
4
5
6
7
Cleared by software
3
8
9
1
2
4
5
6
7
8
D1 D0
Cleared by software
3
D3 D2
Receive Data Byte
D1 D0 ACK D7 D6 D5 D4
Cleared by hardware when
SSPADD is updated with high
byte of address
2
D3 D2
Receive Data Byte
D6 D5 D4
Clock is held low until
update of SSPADD has
taken place
9
P
Bus master
terminates
transfer
SSPOV is set
because SSPBUF is
still full. ACK is not sent.
ACK
FIGURE 17-10:
SDA
Receive First Byte of Address
Clock is held low until
update of SSPADD has
taken place
PIC18F2XK20/4XK20
I2C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 10-BIT ADDRESS)
DS41303G-page 211
DS41303G-page 212
2
1
CKP (SSPCON1<4>)
UA (SSPSTAT<1>)
BF (SSPSTAT<0>)
(PIR1<3>)
SSPIF
1
SCL
S
1
4
1
5
0
6
7
A9 A8
8
UA is set indicating that
the SSPADD needs to be
updated
SSPBUF is written with
contents of SSPSR
3
1
9
ACK
R/W = 0
1
3
4
5
Cleared by software
2
7
UA is set indicating that
SSPADD needs to be
updated
Cleared by hardware when
SSPADD is updated with low
byte of address
6
A6 A5 A4 A3 A2 A1
8
A0
Receive Second Byte of Address
Dummy read of SSPBUF
to clear BF flag
A7
9
ACK
2
3
1
4
1
Cleared by software
1
1
5
0
6
8
9
ACK
R/W=1
1
2
4
5
6
7
P
CKP is automatically cleared by hardware, holding SCL low
CKP is set by software
9
ACK
Bus master
terminates
transfer
Completion of
data transmission
clears BF flag
8
D4 D3 D2 D1 D0
Cleared by software
3
D7 D6 D5
Transmitting Data Byte
Clock is held low until
CKP is set to ‘1’
Write of SSPBUF
BF flag is clear
initiates transmit
at the end of the
third address sequence
7
A9 A8
Cleared by hardware when
SSPADD is updated with high
byte of address.
Dummy read of SSPBUF
to clear BF flag
Sr
1
Receive First Byte of Address
Clock is held low until
update of SSPADD has
taken place
FIGURE 17-11:
SDA
Receive First Byte of Address
Clock is held low until
update of SSPADD has
taken place
PIC18F2XK20/4XK20
I2C™ SLAVE MODE TIMING (TRANSMISSION, 10-BIT ADDRESS)
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.3.4
SSP Mask Register
This register must be initiated prior to setting
SSPM<3:0> bits to select the I2C Slave mode (7-bit or
10-bit address).
2
An SSP Mask (SSPMSK) register is available in I C
Slave mode as a mask for the value held in the
SSPSR register during an address comparison
operation. A zero (‘0’) bit in the SSPMSK register has
the effect of making the corresponding bit in the
SSPSR register a “don’t care”.
The SSP Mask register is active during:
• 7-bit Address mode: address compare of A<7:1>.
• 10-bit Address mode: address compare of A<7:0>
only. The SSP mask has no effect during the
reception of the first (high) byte of the address.
This register is reset to all ‘1’s upon any Reset
condition and, therefore, has no effect on standard
SSP operation until written with a mask value.
REGISTER 17-7:
SSPMSK: SSP MASK REGISTER
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
MSK7
MSK6
MSK5
MSK4
MSK3
MSK2
MSK1
MSK0(1)
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-1
MSK<7:1>: Mask bits
1 = The received address bit n is compared to SSPADD<n> to detect I2C address match
0 = The received address bit n is not used to detect I2C address match
bit 0
MSK<0>: Mask bit for I2C Slave mode, 10-bit Address(1)
I2C Slave mode, 10-bit Address (SSPM<3:0> = 0111):
1 = The received address bit 0 is compared to SSPADD<0> to detect I2C address match
0 = The received address bit 0 is not used to detect I2C address match
Note 1: The MSK0 bit is used only in 10-bit slave mode. In all other modes, this bit has no effect.
 2010 Microchip Technology Inc.
DS41303G-page 213
PIC18F2XK20/4XK20
17.4.4
CLOCK STRETCHING
Both 7-bit and 10-bit Slave modes implement
automatic clock stretching during a transmit sequence.
The SEN bit of the SSPCON2 register allows clock
stretching to be enabled during receives. Setting SEN
will cause the SCL pin to be held low at the end of
each data receive sequence.
17.4.4.1
Clock Stretching for 7-bit Slave
Receive Mode (SEN = 1)
In 7-bit Slave Receive mode, on the falling edge of the
ninth clock at the end of the ACK sequence if the BF
bit is set, the CKP bit of the SSPCON1 register is
automatically cleared, forcing the SCL output to be
held low. The CKP being cleared to ‘0’ will assert the
SCL line low. The CKP bit must be set in the user’s
ISR before reception is allowed to continue. By holding
the SCL line low, the user has time to service the ISR
and read the contents of the SSPBUF before the
master device can initiate another data transfer
sequence. This will prevent buffer overruns from
occurring (see Figure 17-13).
Note 1: If the user reads the contents of the
SSPBUF before the falling edge of the
ninth clock, thus clearing the BF bit, the
CKP bit will not be cleared and clock
stretching will not occur.
2: The CKP bit can be set by software
regardless of the state of the BF bit. The
user should be careful to clear the BF bit
in the ISR before the next receive
sequence in order to prevent an overflow
condition.
17.4.4.2
17.4.4.3
Clock Stretching for 7-bit Slave
Transmit Mode
7-bit Slave Transmit mode implements clock stretching by clearing the CKP bit after the falling edge of the
ninth clock if the BF bit is clear. This occurs regardless
of the state of the SEN bit.
The user’s ISR must set the CKP bit before transmission is allowed to continue. By holding the SCL line
low, the user has time to service the ISR and load the
contents of the SSPBUF before the master device can
initiate another data transfer sequence (see
Figure 17-9).
Note 1: If the user loads the contents of SSPBUF,
setting the BF bit before the falling edge of
the ninth clock, the CKP bit will not be
cleared and clock stretching will not occur.
2: The CKP bit can be set by software
regardless of the state of the BF bit.
17.4.4.4
Clock Stretching for 10-bit Slave
Transmit Mode
In 10-bit Slave Transmit mode, clock stretching is controlled during the first two address sequences by the
state of the UA bit, just as it is in 10-bit Slave Receive
mode. The first two addresses are followed by a third
address sequence which contains the high-order bits
of the 10-bit address and the R/W bit set to ‘1’. After
the third address sequence is performed, the UA bit is
not set, the module is now configured in Transmit
mode and clock stretching is controlled by the BF flag
as in 7-bit Slave Transmit mode (see Figure 17-11).
Clock Stretching for 10-bit Slave
Receive Mode (SEN = 1)
In 10-bit Slave Receive mode during the address
sequence, clock stretching automatically takes place
but CKP is not cleared. During this time, if the UA bit is
set after the ninth clock, clock stretching is initiated.
The UA bit is set after receiving the upper byte of the
10-bit address and following the receive of the second
byte of the 10-bit address with the R/W bit cleared to
‘0’. The release of the clock line occurs upon updating
SSPADD. Clock stretching will occur on each data
receive sequence as described in 7-bit mode.
Note:
If the user polls the UA bit and clears it by
updating the SSPADD register before the
falling edge of the ninth clock occurs and if
the user hasn’t cleared the BF bit by reading the SSPBUF register before that time,
then the CKP bit will still NOT be asserted
low. Clock stretching on the basis of the
state of the BF bit only occurs during a
data sequence, not an address sequence.
DS41303G-page 214
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.4.5
Clock Synchronization and
the CKP bit
When the CKP bit is cleared, the SCL output is forced
to ‘0’. However, clearing the CKP bit will not assert the
SCL output low until the SCL output is already sampled low. Therefore, the CKP bit will not assert the
SCL line until an external I2C master device has
already asserted the SCL line. The SCL output will
remain low until the CKP bit is set and all other
devices on the I2C bus have deasserted SCL. This
ensures that a write to the CKP bit will not violate the
minimum high time requirement for SCL (see
Figure 17-12).
FIGURE 17-12:
CLOCK SYNCHRONIZATION TIMING
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
SDA
DX
DX – 1
SCL
CKP
Master device
asserts clock
Master device
deasserts clock
WR
SSPCON1
 2010 Microchip Technology Inc.
DS41303G-page 215
DS41303G-page 216
CKP
SSPOV (SSPCON1<6>)
BF (SSPSTAT<0>)
(PIR1<3>)
SSPIF
1
SCL
S
A7
2
A6
3
4
A4
5
A3
6
A2
Receiving Address
A5
7
A1
8
9
ACK
R/W = 0
3
4
D4
5
D3
Receiving Data
D5
Cleared by software
2
D6
If BF is cleared
prior to the falling
edge of the 9th clock,
CKP will not be reset
to ‘0’ and no clock
stretching will occur
SSPBUF is read
1
D7
6
D2
7
D1
9
ACK
1
D7
BF is set after falling
edge of the 9th clock,
CKP is reset to ‘0’ and
clock stretching occurs
8
D0
3
4
D4
5
D3
Receiving Data
D5
CKP
written
to ‘1’ in
software
2
D6
Clock is held low until
CKP is set to ‘1’
6
D2
7
D1
8
D0
Bus master
terminates
transfer
P
SSPOV is set
because SSPBUF is
still full. ACK is not sent.
9
ACK
Clock is not held low
because ACK = 1
FIGURE 17-13:
SDA
Clock is not held low
because buffer full bit is
clear prior to falling edge
of 9th clock
PIC18F2XK20/4XK20
I2C™ SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 7-BIT ADDRESS)
 2010 Microchip Technology Inc.
 2010 Microchip Technology Inc.
2
1
UA (SSPSTAT<1>)
SSPOV (SSPCON1<6>)
CKP
3
1
4
1
5
0
6
7
A9 A8
8
UA is set indicating that
the SSPADD needs to be
updated
SSPBUF is written with
contents of SSPSR
Cleared by software
BF (SSPSTAT<0>)
(PIR1<3>)
SSPIF
1
SCL
S
1
9
ACK
R/W = 0
A7
2
4
A4
5
A3
6
A2
Cleared by software
3
A5
7
A1
8
A0
Note: An update of the SSPADD
register before the falling
edge of the ninth clock will
have no effect on UA and
UA will remain set.
UA is set indicating that
SSPADD needs to be
updated
Cleared by hardware when
SSPADD is updated with low
byte of address after falling edge
of ninth clock
Dummy read of SSPBUF
to clear BF flag
1
A6
Receive Second Byte of Address
9
ACK
2
4
5
6
7
9
Note: An update of the SSPADD register before
the falling edge of the ninth clock will have
no effect on UA and UA will remain set.
Cleared by hardware when
SSPADD is updated with high
byte of address after falling edge
of ninth clock
8
ACK
1
4
5
6
7
8
9
ACK
Bus master
terminates
transfer
P
Clock is not held low
because ACK = 1
SSPOV is set
because SSPBUF is
still full. ACK is not sent.
D1 D0
Cleared by software
3
CKP written to ‘1’
by software
2
D3 D2
Receive Data Byte
D7 D6 D5 D4
Clock is held low until
CKP is set to ‘1’
D1 D0
Cleared by software
3
D3 D2
Dummy read of SSPBUF
to clear BF flag
1
D7 D6 D5 D4
Receive Data Byte
Clock is held low until
update of SSPADD has
taken place
FIGURE 17-14:
SDA
Receive First Byte of Address
Clock is held low until
update of SSPADD has
taken place
PIC18F2XK20/4XK20
I2C™ SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 10-BIT ADDRESS)
DS41303G-page 217
PIC18F2XK20/4XK20
17.4.5
GENERAL CALL ADDRESS
SUPPORT
If the general call address matches, the SSPSR is
transferred to the SSPBUF, the BF flag bit is set (eighth
bit) and on the falling edge of the ninth bit (ACK bit), the
SSPIF interrupt flag bit is set.
The addressing procedure for the I2C bus is such that
the first byte after the Start condition usually
determines which device will be the slave addressed by
the master. The exception is the general call address
which can address all devices. When this address is
used, all devices should, in theory, respond with an
Acknowledge.
When the interrupt is serviced, the source for the
interrupt can be checked by reading the contents of the
SSPBUF. The value can be used to determine if the
address was device specific or a general call address.
In 10-bit mode, the SSPADD is required to be updated
for the second half of the address to match and the UA
bit of the SSPSTAT register is set. If the general call
address is sampled when the GCEN bit is set, while the
slave is configured in 10-bit Address mode, then the
second half of the address is not necessary, the UA bit
will not be set and the slave will begin receiving data
after the Acknowledge (Figure 17-15).
The general call address is one of eight addresses
reserved for specific purposes by the I2C protocol. It
consists of all ‘0’s with R/W = 0.
The general call address is recognized when the
GCEN bit of the SSPCON2 is set. Following a Start bit
detect, 8 bits are shifted into the SSPSR and the
address is compared against the SSPADD. It is also
compared to the general call address and fixed in hardware.
FIGURE 17-15:
SLAVE MODE GENERAL CALL ADDRESS SEQUENCE
(7 OR 10-BIT ADDRESS MODE)
Address is compared to General Call Address
after ACK, set interrupt
Receiving Data
R/W = 0
General Call Address
SDA
ACK D7
ACK
D6
D5
D4
D3
D2
D1
D0
2
3
4
5
6
7
8
SCL
S
1
2
3
4
5
6
7
8
9
1
9
SSPIF
BF (SSPSTAT<0>)
Cleared by software
SSPBUF is read
SSPOV (SSPCON1<6>)
‘0’
GCEN (SSPCON2<7>)
‘1’
DS41303G-page 218
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
MASTER MODE
Note:
Master mode is enabled by setting and clearing the
appropriate SSPM bits in SSPCON1 and by setting the
SSPEN bit. In Master mode, the SCL and SDA lines
are manipulated by the MSSP hardware.
Master mode of operation is supported by interrupt
generation on the detection of the Start and Stop conditions. The Stop (P) and Start (S) bits are cleared from
a Reset or when the MSSP module is disabled. Control
of the I 2C bus may be taken when the P bit is set, or the
bus is Idle, with both the S and P bits clear.
The following events will cause the SSP Interrupt Flag
bit, SSPIF, to be set (SSP interrupt, if enabled):
In Firmware Controlled Master mode, user code
conducts all I 2C bus operations based on Start and
Stop bit conditions.
•
•
•
•
•
Once Master mode is enabled, the user has six
options.
1.
2.
3.
4.
5.
6.
Assert a Start condition on SDA and SCL.
Assert a Repeated Start condition on SDA and
SCL.
Write to the SSPBUF register initiating
transmission of data/address.
Configure the I2C port to receive data.
Generate an Acknowledge condition at the end
of a received byte of data.
Generate a Stop condition on SDA and SCL.
FIGURE 17-16:
The MSSP module, when configured in
I2C Master mode, does not allow queueing
of events. For instance, the user is not
allowed to initiate a Start condition and
immediately write the SSPBUF register to
initiate transmission before the Start
condition is complete. In this case, the
SSPBUF will not be written to and the
WCOL bit will be set, indicating that a write
to the SSPBUF did not occur.
Start condition
Stop condition
Data transfer byte transmitted/received
Acknowledge transmit
Repeated Start
MSSP BLOCK DIAGRAM (I2C™ MASTER MODE)
Internal
Data Bus
Read
SSPM<3:0>
SSPADD<7:0>
Write
SSPBUF
Baud
Rate
Generator
Shift
Clock
SDA
SDA In
SCL In
Bus Collision
 2010 Microchip Technology Inc.
LSb
Start bit, Stop bit,
Acknowledge
Generate
Start bit Detect
Stop bit Detect
Write Collision Detect
Clock Arbitration
State Counter for
end of XMIT/RCV
Clock Cntl
SCL
Receive Enable
SSPSR
MSb
Clock Arbitrate/WCOL Detect
(hold off clock source)
17.4.6
Set/Reset, S, P, WCOL (SSPSTAT)
Set SSPIF, BCLIF
Reset ACKSTAT, PEN (SSPCON2)
DS41303G-page 219
PIC18F2XK20/4XK20
17.4.6.1
I2C Master Mode Operation
The master device generates all of the serial clock
pulses and the Start and Stop conditions. A transfer is
ended with a Stop condition or with a Repeated Start
condition. Since the Repeated Start condition is also
the beginning of the next serial transfer, the I2C bus will
not be released.
In Master Transmitter mode, serial data is output
through SDA, while SCL outputs the serial clock. The
first byte transmitted contains the slave address of the
receiving device (7 bits) and the Read/Write (R/W) bit.
In this case, the R/W bit will be logic ‘0’. Serial data is
transmitted 8 bits at a time. After each byte is transmitted, an Acknowledge bit is received. Start and Stop
conditions are output to indicate the beginning and the
end of a serial transfer.
In Master Receive mode, the first byte transmitted contains the slave address of the transmitting device
(7 bits) and the R/W bit. In this case, the R/W bit will be
logic ‘1’. Thus, the first byte transmitted is a 7-bit slave
address followed by a ‘1’ to indicate the receive bit.
Serial data is received via SDA, while SCL outputs the
serial clock. Serial data is received 8 bits at a time. After
each byte is received, an Acknowledge bit is transmitted. Start and Stop conditions indicate the beginning
and end of transmission.
The Baud Rate Generator used for the SPI mode
operation is used to set the SCL clock frequency for
either 100 kHz, 400 kHz or 1 MHz I2C operation. See
Section 17.4.7 “Baud Rate” for more detail.
DS41303G-page 220
A typical transmit sequence would go as follows:
1.
The user generates a Start condition by setting
the SEN bit of the SSPCON2 register.
2. SSPIF is set. The MSSP module will wait the
required start time before any other operation
takes place.
3. The user loads the SSPBUF with the slave
address to transmit.
4. Address is shifted out the SDA pin until all 8 bits
are transmitted.
5. The MSSP module shifts in the ACK bit from the
slave device and writes its value into the
ACKSTAT bit of the SSPCON2 register.
6. The MSSP module generates an interrupt at the
end of the ninth clock cycle by setting the SSPIF
bit.
7. The user loads the SSPBUF with eight bits of
data.
8. Data is shifted out the SDA pin until all 8 bits are
transmitted.
9. The MSSP module shifts in the ACK bit from the
slave device and writes its value into the
ACKSTAT bit of the SSPCON2 register.
10. The MSSP module generates an interrupt at the
end of the ninth clock cycle by setting the SSPIF
bit.
11. The user generates a Stop condition by setting
the PEN bit of the SSPCON2 register.
12. Interrupt is generated once the Stop condition is
complete.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.7
BAUD RATE
2
In I C Master mode, the Baud Rate Generator (BRG)
reload value is placed in the SSPADD register
(Figure 17-17). When a write occurs to SSPBUF, the
Baud Rate Generator will automatically begin counting.
The BRG counts down to ‘0’ and stops until another
reload has taken place. The BRG count is decremented twice per instruction cycle (TCY) on the Q2 and
Q4 clocks. In I2C Master mode, the BRG is reloaded
automatically. One half of the SCL period is equal to
[(SSPADD+1)  2]/FOSC. Therefore SSPADD =
(FCY/FSCL) -1.
FIGURE 17-17:
Once the given operation is complete (i.e.,
transmission of the last data bit is followed by ACK), the
internal clock will automatically stop counting and the
SCL pin will remain in its last state.
Table 17-3 demonstrates clock rates based on
instruction cycles and the BRG value loaded into
SSPADD.
The minimum SSPADD value for baud rate generation
is 0x03.
BAUD RATE GENERATOR BLOCK DIAGRAM
SSPM<3:0>
SSPM<3:0>
Reload
SCL
Control
CLKOUT
TABLE 17-3:
Note 1:
SSPADD<7:0>
Reload
BRG Down Counter
FOSC/2
I2C™ CLOCK RATE W/BRG
FOSC
FCY
BRG Value
FSCL
(2 Rollovers of BRG)
64 MHz
16 MHz
27h
400 kHz(1)
64 MHz
16 MHz
32h
313.7 kHz
64 MHz
16 MHz
3Fh
250 kHz
40 MHz
10 MHz
18h
400 kHz(1)
40 MHz
10 MHz
1Fh
312.5 kHz
40 MHz
10 MHz
63h
100 kHz
16 MHz
4 MHz
09h
400 kHz(1)
16 MHz
4 MHz
0Ch
308 kHz
16 MHz
4 MHz
27h
100 kHz
4 MHz
1 MHz
09h
100 kHz
The I2C interface does not conform to the 400 kHz I2C specification (which applies to rates greater than
100 kHz) in all details, but may be used with care where higher rates are required by the application.
 2010 Microchip Technology Inc.
DS41303G-page 221
PIC18F2XK20/4XK20
17.4.7.1
Clock Arbitration
Clock arbitration occurs when the master, during any
receive, transmit or Repeated Start/Stop condition,
deasserts the SCL pin (SCL allowed to float high).
When the SCL pin is allowed to float high, the Baud
Rate Generator (BRG) is suspended from counting
until the SCL pin is actually sampled high. When the
SCL pin is sampled high, the Baud Rate Generator is
reloaded with the contents of SSPADD<7:0> and
begins counting. This ensures that the SCL high time
will always be at least one BRG rollover count in the
event that the clock is held low by an external device
(Figure 17-18).
FIGURE 17-18:
BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION
SDA
DX
DX – 1
SCL deasserted but slave holds
SCL low (clock arbitration)
SCL allowed to transition high
SCL
BRG decrements on
Q2 and Q4 cycles
BRG
Value
03h
02h
01h
00h (hold off)
03h
02h
SCL is sampled high, reload takes
place and BRG starts its count
BRG
Reload
DS41303G-page 222
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.8
I2C MASTER MODE START
CONDITION TIMING
Note:
To initiate a Start condition, the user sets the Start
Enable bit, SEN bit of the SSPCON2 register. If the
SDA and SCL pins are sampled high, the Baud Rate
Generator is reloaded with the contents of
SSPADD<6:0> and starts its count. If SCL and SDA are
both sampled high when the Baud Rate Generator
times out (TBRG), the SDA pin is driven low. The action
of the SDA being driven low while SCL is high is the
Start condition and causes the S bit of the SSPSTAT1
register to be set. Following this, the Baud Rate Generator is reloaded with the contents of SSPADD<7:0>
and resumes its count. When the Baud Rate Generator
times out (TBRG), the SEN bit of the SSPCON2 register
will be automatically cleared by hardware; the Baud
Rate Generator is suspended, leaving the SDA line
held low and the Start condition is complete.
FIGURE 17-19:
17.4.8.1
If at the beginning of the Start condition,
the SDA and SCL pins are already sampled low, or if during the Start condition, the
SCL line is sampled low before the SDA
line is driven low, a bus collision occurs,
the Bus Collision Interrupt Flag, BCLIF, is
set, the Start condition is aborted and the
I2C module is reset into its Idle state.
WCOL Status Flag
If the user writes the SSPBUF when a Start sequence
is in progress, the WCOL is set and the contents of the
buffer are unchanged (the write doesn’t occur).
Note:
Because queueing of events is not
allowed, writing to the lower 5 bits of
SSPCON2 is disabled until the Start
condition is complete.
FIRST START BIT TIMING
Set S bit (SSPSTAT<3>)
Write to SEN bit occurs here
SDA = 1,
SCL = 1
TBRG
At completion of Start bit,
hardware clears SEN bit
and sets SSPIF bit
TBRG
Write to SSPBUF occurs here
1st bit
SDA
2nd bit
TBRG
SCL
TBRG
S
 2010 Microchip Technology Inc.
DS41303G-page 223
PIC18F2XK20/4XK20
17.4.9
I2C MASTER MODE REPEATED
START CONDITION TIMING
Note 1: If RSEN is programmed while any other
event is in progress, it will not take effect.
A Repeated Start condition occurs when the RSEN bit
of the SSPCON2 register is programmed high and the
I2C logic module is in the Idle state. When the RSEN bit
is set, the SCL pin is asserted low. When the SCL pin
is sampled low, the Baud Rate Generator is loaded with
the contents of SSPADD<5:0> and begins counting.
The SDA pin is released (brought high) for one Baud
Rate Generator count (TBRG). When the Baud Rate
Generator times out, if SDA is sampled high, the SCL
pin will be deasserted (brought high). When SCL is
sampled high, the Baud Rate Generator is reloaded
with the contents of SSPADD<7:0> and begins counting. SDA and SCL must be sampled high for one TBRG.
This action is then followed by assertion of the SDA pin
(SDA = 0) for one TBRG while SCL is high. Following
this, the RSEN bit of the SSPCON2 register will be
automatically cleared and the Baud Rate Generator will
not be reloaded, leaving the SDA pin held low. As soon
as a Start condition is detected on the SDA and SCL
pins, the S bit of the SSPSTAT register will be set. The
SSPIF bit will not be set until the Baud Rate Generator
has timed out.
2: A bus collision during the Repeated Start
condition occurs if:
• SDA is sampled low when SCL goes
from low-to-high.
• SCL goes low before SDA is
asserted low. This may indicate that
another master is attempting to
transmit a data ‘1’.
Immediately following the SSPIF bit getting set, the user
may write the SSPBUF with the 7-bit address in 7-bit
mode or the default first address in 10-bit mode. After the
first eight bits are transmitted and an ACK is received,
the user may then transmit an additional eight bits of
address (10-bit mode) or eight bits of data (7-bit mode).
17.4.9.1
If the user writes the SSPBUF when a Repeated Start
sequence is in progress, the WCOL is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
Note:
FIGURE 17-20:
WCOL Status Flag
Because queueing of events is not
allowed, writing of the lower 5 bits of
SSPCON2 is disabled until the Repeated
Start condition is complete.
REPEAT START CONDITION WAVEFORM
S bit set by hardware
Write to SSPCON2
occurs here.
SDA = 1,
SCL (no change).
SDA = 1,
SCL = 1
TBRG
TBRG
At completion of Start bit,
hardware clears RSEN bit
and sets SSPIF
TBRG
1st bit
SDA
RSEN bit set by hardware
on falling edge of ninth clock,
end of Xmit
Write to SSPBUF occurs here
TBRG
SCL
TBRG
Sr = Repeated Start
DS41303G-page 224
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.10
I2C MASTER MODE
TRANSMISSION
Transmission of a data byte, a 7-bit address or the
other half of a 10-bit address is accomplished by simply
writing a value to the SSPBUF register. This action will
set the Buffer Full flag bit, BF and allow the Baud Rate
Generator to begin counting and start the next transmission. Each bit of address/data will be shifted out
onto the SDA pin after the falling edge of SCL is
asserted (see data hold time specification
parameter 106). SCL is held low for one Baud Rate
Generator rollover count (TBRG). Data should be valid
before SCL is released high (see data setup time specification parameter 107). When the SCL pin is released
high, it is held that way for TBRG. The data on the SDA
pin must remain stable for that duration and some hold
time after the next falling edge of SCL. After the eighth
bit is shifted out (the falling edge of the eighth clock),
the BF flag is cleared and the master releases SDA.
This allows the slave device being addressed to
respond with an ACK bit during the ninth bit time if an
address match occurred, or if data was received properly. The status of ACK is written into the ACKDT bit on
the falling edge of the ninth clock. If the master receives
an Acknowledge, the Acknowledge Status bit,
ACKSTAT, is cleared. If not, the bit is set. After the ninth
clock, the SSPIF bit is set and the master clock (Baud
Rate Generator) is suspended until the next data byte
is loaded into the SSPBUF, leaving SCL low and SDA
unchanged (Figure 17-21).
After the write to the SSPBUF, each bit of the address
will be shifted out on the falling edge of SCL until all
seven address bits and the R/W bit are completed. On
the falling edge of the eighth clock, the master will
deassert the SDA pin, allowing the slave to respond
with an Acknowledge. On the falling edge of the ninth
clock, the master will sample the SDA pin to see if the
address was recognized by a slave. The status of the
ACK bit is loaded into the ACKSTAT Status bit of the
SSPCON2 register. Following the falling edge of the
ninth clock transmission of the address, the SSPIF is
set, the BF flag is cleared and the Baud Rate Generator
is turned off until another write to the SSPBUF takes
place, holding SCL low and allowing SDA to float.
17.4.10.1
BF Status Flag
In Transmit mode, the BF bit of the SSPSTAT register
is set when the CPU writes to SSPBUF and is cleared
when all 8 bits are shifted out.
17.4.10.2
17.4.10.3
ACKSTAT Status Flag
In Transmit mode, the ACKSTAT bit of the SSPCON2
register is cleared when the slave has sent an Acknowledge (ACK = 0) and is set when the slave does not
Acknowledge (ACK = 1). A slave sends an Acknowledge when it has recognized its address (including a
general call), or when the slave has properly received
its data.
17.4.11
I2C MASTER MODE RECEPTION
Master mode reception is enabled by programming the
Receive Enable bit, RCEN bit of the SSPCON2
register.
Note:
The MSSP module must be in an Idle state
before the RCEN bit is set or the RCEN bit
will be disregarded.
The Baud Rate Generator begins counting and on each
rollover, the state of the SCL pin changes
(high-to-low/low-to-high) and data is shifted into the
SSPSR. After the falling edge of the eighth clock, the
receive enable flag is automatically cleared, the contents of the SSPSR are loaded into the SSPBUF, the
BF flag bit is set, the SSPIF flag bit is set and the Baud
Rate Generator is suspended from counting, holding
SCL low. The MSSP is now in Idle state awaiting the
next command. When the buffer is read by the CPU,
the BF flag bit is automatically cleared. The user can
then send an Acknowledge bit at the end of reception
by setting the Acknowledge Sequence Enable, ACKEN
bit of the SSPCON2 register.
17.4.11.1
BF Status Flag
In receive operation, the BF bit is set when an address
or data byte is loaded into SSPBUF from SSPSR. It is
cleared when the SSPBUF register is read.
17.4.11.2
SSPOV Status Flag
In receive operation, the SSPOV bit is set when 8 bits
are received into the SSPSR and the BF flag bit is
already set from a previous reception.
17.4.11.3
WCOL Status Flag
If the user writes the SSPBUF when a receive is
already in progress (i.e., SSPSR is still shifting in a data
byte), the WCOL bit is set and the contents of the buffer
are unchanged (the write doesn’t occur).
WCOL Status Flag
If the user writes the SSPBUF when a transmit is
already in progress (i.e., SSPSR is still shifting out a
data byte), the WCOL is set and the contents of the buffer are unchanged (the write doesn’t occur).
WCOL must be cleared by software.
 2010 Microchip Technology Inc.
DS41303G-page 225
DS41303G-page 226
S
R/W
PEN
SEN
BF (SSPSTAT<0>)
SSPIF
SCL
SDA
A6
A5
A4
A3
A2
A1
3
4
5
Cleared by software
2
6
7
8
9
After Start condition, SEN cleared by hardware
SSPBUF written
1
D7
1
SCL held low
while CPU
responds to SSPIF
ACK = 0
R/W = 0
SSPBUF written with 7-bit address and R/W
start transmit
A7
Transmit Address to Slave
3
D5
4
D4
5
D3
6
D2
7
D1
8
D0
SSPBUF is written by software
Cleared by software service routine
from SSP interrupt
2
D6
Transmitting Data or Second Half
of 10-bit Address
From slave, clear ACKSTAT bit SSPCON2<6>
P
Cleared by software
9
ACK
ACKSTAT in
SSPCON2 = 1
FIGURE 17-21:
SEN = 0
Write SSPCON2<0> SEN = 1
Start condition begins
PIC18F2XK20/4XK20
I 2C™ MASTER MODE WAVEFORM (TRANSMISSION, 7 OR 10-BIT ADDRESS)
 2010 Microchip Technology Inc.
 2010 Microchip Technology Inc.
S
ACKEN
SSPOV
BF
(SSPSTAT<0>)
SDA = 0, SCL = 1
while CPU
responds to SSPIF
SSPIF
SCL
SDA
1
A7
2
4
5
6
Cleared by software
3
A6 A5 A4 A3 A2
Transmit Address to Slave
7
A1
8
9
R/W = 0
ACK
ACK from Slave
2
3
5
6
7
8
D0
9
ACK
2
3
4
5
6
7
Cleared by software
Set SSPIF interrupt
at end of Acknowledge
sequence
Data shifted in on falling edge of CLK
1
D7 D6 D5 D4 D3 D2 D1
Cleared in
software
Set SSPIF at end
of receive
9
ACK is not sent
ACK
P
Set SSPIF interrupt
at end of Acknowledge sequence
Bus master
terminates
transfer
Set P bit
(SSPSTAT<4>)
and SSPIF
PEN bit = 1
written here
SSPOV is set because
SSPBUF is still full
8
D0
RCEN cleared
automatically
Set ACKEN, start Acknowledge sequence
SDA = ACKDT = 1
Receiving Data from Slave
RCEN = 1, start
next receive
ACK from Master
SDA = ACKDT = 0
Last bit is shifted into SSPSR and
contents are unloaded into SSPBUF
Cleared by software
Set SSPIF interrupt
at end of receive
4
Cleared by software
1
D7 D6 D5 D4 D3 D2 D1
Receiving Data from Slave
RCEN cleared
automatically
Master configured as a receiver
by programming SSPCON2<3> (RCEN = 1)
FIGURE 17-22:
SEN = 0
Write to SSPBUF occurs here,
start XMIT
Write to SSPCON2<0> (SEN = 1),
begin Start condition
Write to SSPCON2<4>
to start Acknowledge sequence
SDA = ACKDT (SSPCON2<5>) = 0
PIC18F2XK20/4XK20
I 2C™ MASTER MODE WAVEFORM (RECEPTION, 7-BIT ADDRESS)
DS41303G-page 227
PIC18F2XK20/4XK20
17.4.12
ACKNOWLEDGE SEQUENCE
TIMING
17.4.13
A Stop bit is asserted on the SDA pin at the end of a
receive/transmit by setting the Stop Sequence Enable
bit, PEN bit of the SSPCON2 register. At the end of a
receive/transmit, the SCL line is held low after the
falling edge of the ninth clock. When the PEN bit is set,
the master will assert the SDA line low. When the SDA
line is sampled low, the Baud Rate Generator is
reloaded and counts down to ‘0’. When the Baud Rate
Generator times out, the SCL pin will be brought high
and one TBRG (Baud Rate Generator rollover count)
later, the SDA pin will be deasserted. When the SDA
pin is sampled high while SCL is high, the P bit of the
SSPSTAT register is set. A TBRG later, the PEN bit is
cleared and the SSPIF bit is set (Figure 17-24).
An Acknowledge sequence is enabled by setting the
Acknowledge Sequence Enable bit, ACKEN bit of the
SSPCON2 register. When this bit is set, the SCL pin is
pulled low and the contents of the Acknowledge data bit
are presented on the SDA pin. If the user wishes to generate an Acknowledge, then the ACKDT bit should be
cleared. If not, the user should set the ACKDT bit before
starting an Acknowledge sequence. The Baud Rate
Generator then counts for one rollover period (TBRG)
and the SCL pin is deasserted (pulled high). When the
SCL pin is sampled high (clock arbitration), the Baud
Rate Generator counts for TBRG. The SCL pin is then
pulled low. Following this, the ACKEN bit is automatically
cleared, the Baud Rate Generator is turned off and the
MSSP module then goes into Idle mode (Figure 17-23).
17.4.12.1
17.4.13.1
WCOL Status Flag
If the user writes the SSPBUF when a Stop sequence
is in progress, then the WCOL bit is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
WCOL Status Flag
If the user writes the SSPBUF when an Acknowledge
sequence is in progress, then WCOL is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
FIGURE 17-23:
STOP CONDITION TIMING
ACKNOWLEDGE SEQUENCE WAVEFORM
Acknowledge sequence starts here,
write to SSPCON2
ACKEN = 1, ACKDT = 0
ACKEN automatically cleared
TBRG
TBRG
SDA
ACK
D0
SCL
8
9
SSPIF
SSPIF set at
the end of receive
Cleared in
software
Cleared in
software
SSPIF set at the end
of Acknowledge sequence
Note: TBRG = one Baud Rate Generator period.
FIGURE 17-24:
STOP CONDITION RECEIVE OR TRANSMIT MODE
SCL = 1 for TBRG, followed by SDA = 1 for TBRG
after SDA sampled high. P bit (SSPSTAT<4>) is set.
Write to SSPCON2,
set PEN
PEN bit (SSPCON2<2>) is cleared by
hardware and the SSPIF bit is set
Falling edge of
9th clock
TBRG
SCL
SDA
ACK
P
TBRG
TBRG
TBRG
SCL brought high after TBRG
SDA asserted low before rising edge of clock
to setup Stop condition
Note: TBRG = one Baud Rate Generator period.
DS41303G-page 228
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.14
SLEEP OPERATION
17.4.17
2
While in Sleep mode, the I C module can receive
addresses or data and when an address match or complete byte transfer occurs, wake the processor from
Sleep (if the MSSP interrupt is enabled).
17.4.15
EFFECTS OF A RESET
A Reset disables the MSSP module and terminates the
current transfer.
17.4.16
MULTI-MASTER MODE
In Multi-Master mode, the interrupt generation on the
detection of the Start and Stop conditions allows the
determination of when the bus is free. The Stop (P) and
Start (S) bits are cleared from a Reset or when the
MSSP module is disabled. Control of the I 2C bus may
be taken when the P bit of the SSPSTAT register is set,
or the bus is Idle, with both the S and P bits clear. When
the bus is busy, enabling the SSP interrupt will generate the interrupt when the Stop condition occurs.
In multi-master operation, the SDA line must be
monitored for arbitration to see if the signal level is the
expected output level. This check is performed by
hardware with the result placed in the BCLIF bit.
The states where arbitration can be lost are:
•
•
•
•
•
Address Transfer
Data Transfer
A Start Condition
A Repeated Start Condition
An Acknowledge Condition
MULTI -MASTER COMMUNICATION,
BUS COLLISION AND BUS
ARBITRATION
Multi-Master mode support is achieved by bus arbitration. When the master outputs address/data bits onto
the SDA pin, arbitration takes place when the master
outputs a ‘1’ on SDA, by letting SDA float high and
another master asserts a ‘0’. When the SCL pin floats
high, data should be stable. If the expected data on
SDA is a ‘1’ and the data sampled on the SDA pin = 0,
then a bus collision has taken place. The master will set
the Bus Collision Interrupt Flag, BCLIF and reset the
I2C port to its Idle state (Figure 17-25).
If a transmit was in progress when the bus collision
occurred, the transmission is halted, the BF flag is
cleared, the SDA and SCL lines are deasserted and the
SSPBUF can be written to. When the user services the
bus collision Interrupt Service Routine and if the I2C
bus is free, the user can resume communication by
asserting a Start condition.
If a Start, Repeated Start, Stop or Acknowledge condition was in progress when the bus collision occurred, the
condition is aborted, the SDA and SCL lines are deasserted and the respective control bits in the SSPCON2
register are cleared. When the user services the bus collision Interrupt Service Routine and if the I2C bus is free,
the user can resume communication by asserting a Start
condition.
The master will continue to monitor the SDA and SCL
pins. If a Stop condition occurs, the SSPIF bit will be set.
A write to the SSPBUF will start the transmission of
data at the first data bit, regardless of where the
transmitter left off when the bus collision occurred.
In Multi-Master mode, the interrupt generation on the
detection of Start and Stop conditions allows the determination of when the bus is free. Control of the I2C bus
can be taken when the P bit is set in the SSPSTAT
register, or the bus is Idle and the S and P bits are
cleared.
FIGURE 17-25:
BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE
Data changes
while SCL = 0
SDA line pulled low
by another source
SDA released
by master
Sample SDA. While SCL is high,
data doesn’t match what is driven
by the master.
Bus collision has occurred.
SDA
SCL
Set bus collision
interrupt (BCLIF)
BCLIF
 2010 Microchip Technology Inc.
DS41303G-page 229
PIC18F2XK20/4XK20
17.4.17.1
Bus Collision During a Start
Condition
During a Start condition, a bus collision occurs if:
a)
b)
SDA or SCL are sampled low at the beginning of
the Start condition (Figure 17-26).
SCL is sampled low before SDA is asserted low
(Figure 17-27).
During a Start condition, both the SDA and the SCL
pins are monitored.
If the SDA pin is sampled low during this count, the
BRG is reset and the SDA line is asserted early
(Figure 17-28). If, however, a ‘1’ is sampled on the SDA
pin, the SDA pin is asserted low at the end of the BRG
count. The Baud Rate Generator is then reloaded and
counts down to 0; if the SCL pin is sampled as ‘0’
during this time, a bus collision does not occur. At the
end of the BRG count, the SCL pin is asserted low.
Note:
If the SDA pin is already low, or the SCL pin is already
low, then all of the following occur:
• the Start condition is aborted,
• the BCLIF flag is set and
• the MSSP module is reset to its Idle state
(Figure 17-26).
The Start condition begins with the SDA and SCL pins
deasserted. When the SDA pin is sampled high, the
Baud Rate Generator is loaded from SSPADD<7:0>
and counts down to 0. If the SCL pin is sampled low
while SDA is high, a bus collision occurs because it is
assumed that another master is attempting to drive a
data ‘1’ during the Start condition.
FIGURE 17-26:
The reason that bus collision is not a factor
during a Start condition is that no two bus
masters can assert a Start condition at the
exact same time. Therefore, one master
will always assert SDA before the other.
This condition does not cause a bus collision because the two masters must be
allowed to arbitrate the first address following the Start condition. If the address is
the same, arbitration must be allowed to
continue into the data portion, Repeated
Start or Stop conditions.
BUS COLLISION DURING START CONDITION (SDA ONLY)
SDA goes low before the SEN bit is set.
Set BCLIF,
S bit and SSPIF set because
SDA = 0, SCL = 1.
SDA
SCL
Set SEN, enable Start
condition if SDA = 1, SCL = 1
SEN cleared automatically because of bus collision.
SSP module reset into Idle state.
SEN
BCLIF
SDA sampled low before
Start condition. Set BCLIF.
S bit and SSPIF set because
SDA = 0, SCL = 1.
SSPIF and BCLIF are
cleared by software
S
SSPIF
SSPIF and BCLIF are
cleared by software
DS41303G-page 230
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 17-27:
BUS COLLISION DURING START CONDITION (SCL = 0)
SDA = 0, SCL = 1
TBRG
TBRG
SDA
Set SEN, enable Start
sequence if SDA = 1, SCL = 1
SCL
SCL = 0 before SDA = 0,
bus collision occurs. Set BCLIF.
SEN
SCL = 0 before BRG time-out,
bus collision occurs. Set BCLIF.
BCLIF
Interrupt cleared
by software
S
‘0’
‘0’
SSPIF
‘0’
‘0’
FIGURE 17-28:
BRG RESET DUE TO SDA ARBITRATION DURING START CONDITION
SDA = 0, SCL = 1
Set S
Less than TBRG
SDA
Set SSPIF
TBRG
SDA pulled low by other master.
Reset BRG and assert SDA.
SCL
S
SCL pulled low after BRG
time-out
SEN
BCLIF
Set SEN, enable START
sequence if SDA = 1, SCL = 1
‘0’
S
SSPIF
SDA = 0, SCL = 1,
set SSPIF
 2010 Microchip Technology Inc.
Interrupts cleared
by software
DS41303G-page 231
PIC18F2XK20/4XK20
17.4.17.2
Bus Collision During a Repeated
Start Condition
If SDA is low, a bus collision has occurred (i.e., another
master is attempting to transmit a data ‘0’, Figure 17-29).
If SDA is sampled high, the BRG is reloaded and begins
counting. If SDA goes from high-to-low before the BRG
times out, no bus collision occurs because no two
masters can assert SDA at exactly the same time.
During a Repeated Start condition, a bus collision
occurs if:
a)
b)
A low level is sampled on SDA when SCL goes
from low level to high level.
SCL goes low before SDA is asserted low,
indicating that another master is attempting to
transmit a data ‘1’.
If SCL goes from high-to-low before the BRG times out
and SDA has not already been asserted, a bus collision
occurs. In this case, another master is attempting to
transmit a data ‘1’ during the Repeated Start condition,
see Figure 17-30.
When the user deasserts SDA and the pin is allowed to
float high, the BRG is loaded with SSPADD<7:0> and
counts down to 0. The SCL pin is then deasserted and
when sampled high, the SDA pin is sampled.
FIGURE 17-29:
If, at the end of the BRG time-out, both SCL and SDA
are still high, the SDA pin is driven low and the BRG is
reloaded and begins counting. At the end of the count,
regardless of the status of the SCL pin, the SCL pin is
driven low and the Repeated Start condition is
complete.
BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)
SDA
SCL
Sample SDA when SCL goes high.
If SDA = 0, set BCLIF and release SDA and SCL.
RSEN
BCLIF
Cleared by software
‘0’
S
‘0’
SSPIF
FIGURE 17-30:
BUS COLLISION DURING REPEATED START CONDITION (CASE 2)
TBRG
TBRG
SDA
SCL
BCLIF
SCL goes low before SDA,
set BCLIF. Release SDA and SCL.
Interrupt cleared
by software
RSEN
S
‘0’
SSPIF
DS41303G-page 232
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
17.4.17.3
Bus Collision During a Stop
Condition
The Stop condition begins with SDA asserted low.
When SDA is sampled low, the SCL pin is allowed to
float. When the pin is sampled high (clock arbitration),
the Baud Rate Generator is loaded with SSPADD<7:0>
and counts down to 0. After the BRG times out, SDA is
sampled. If SDA is sampled low, a bus collision has
occurred. This is due to another master attempting to
drive a data ‘0’ (Figure 17-31). If the SCL pin is
sampled low before SDA is allowed to float high, a bus
collision occurs. This is another case of another master
attempting to drive a data ‘0’ (Figure 17-32).
Bus collision occurs during a Stop condition if:
a)
b)
After the SDA pin has been deasserted and
allowed to float high, SDA is sampled low after
the BRG has timed out.
After the SCL pin is deasserted, SCL is sampled
low before SDA goes high.
FIGURE 17-31:
BUS COLLISION DURING A STOP CONDITION (CASE 1)
TBRG
TBRG
TBRG
SDA sampled
low after TBRG,
set BCLIF
SDA
SDA asserted low
SCL
PEN
BCLIF
P
‘0’
SSPIF
‘0’
FIGURE 17-32:
BUS COLLISION DURING A STOP CONDITION (CASE 2)
TBRG
TBRG
TBRG
SDA
Assert SDA
SCL
SCL goes low before SDA goes high,
set BCLIF
PEN
BCLIF
P
‘0’
SSPIF
‘0’
 2010 Microchip Technology Inc.
DS41303G-page 233
PIC18F2XK20/4XK20
TABLE 17-4:
SUMMARY OF REGISTERS ASSOCIATED WITH I2C™
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values on
page
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
Name
PIE2
SSPADD
SSP Address Register in I2C™ Slave Mode. SSP Baud Rate Reload Register in I2C Master Mode.
60
SSPBUF
SSP Receive Buffer/Transmit Register
60
SSPCON1
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
60
SSPCON2
GCEN
ACKSTAT
ACKDT
ACKEN
RCEN
PEN
RSEN
SEN
60
SSPMSK
MSK7
MSK6
MSK5
MSK4
MSK3
MSK2
MSK1
MSK0
63
SSPSTAT
TRISC
Legend:
Note 1:
SMP
CKE
D/A
P
S
R/W
UA
BF
60
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
62
— = unimplemented, read as ‘0’. Shaded cells are not used by PORTA.
Not implemented on PIC18F2XK20 devices
DS41303G-page 234
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
NOTES:
 2010 Microchip Technology Inc.
DS41303G-page 235
PIC18F2XK20/4XK20
DS41303G-page 236
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
18.0
ENHANCED UNIVERSAL
SYNCHRONOUS
ASYNCHRONOUS RECEIVER
TRANSMITTER (EUSART)
The EUSART module includes the following capabilities:
•
•
•
•
•
•
•
•
•
•
The Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) module is a serial I/O
communications peripheral. It contains all the clock
generators, shift registers and data buffers necessary
to perform an input or output serial data transfer
independent of device program execution. The
EUSART, also known as a Serial Communications
Interface (SCI), can be configured as a full-duplex
asynchronous system or half-duplex synchronous
system.
Full-Duplex
mode
is
useful
for
communications with peripheral systems, such as CRT
terminals and personal computers. Half-Duplex
Synchronous mode is intended for communications
with peripheral devices, such as A/D or D/A integrated
circuits, serial EEPROMs or other microcontrollers.
These devices typically do not have internal clocks for
baud rate generation and require the external clock
signal provided by a master synchronous device.
FIGURE 18-1:
Full-duplex asynchronous transmit and receive
Two-character input buffer
One-character output buffer
Programmable 8-bit or 9-bit character length
Address detection in 9-bit mode
Input buffer overrun error detection
Received character framing error detection
Half-duplex synchronous master
Half-duplex synchronous slave
Programmable clock and data polarity
The EUSART module implements the following
additional features, making it ideally suited for use in
Local Interconnect Network (LIN) bus systems:
• Automatic detection and calibration of the baud rate
• Wake-up on Break reception
• 13-bit Break character transmit
Block diagrams of the EUSART transmitter and
receiver are shown in Figure 18-1 and Figure 18-2.
EUSART TRANSMIT BLOCK DIAGRAM
Data Bus
TXIE
Interrupt
TXIF
TXREG Register
8
MSb
LSb
(8)
0
• • •
TX/CK pin
Pin Buffer
and Control
Transmit Shift Register (TSR)
TXEN
TRMT
Baud Rate Generator
FOSC
TX9
n
BRG16
+1
SPBRGH
÷n
SPBRG
Multiplier
x4
x16 x64
SYNC
1 X 0 0
0
BRGH
X 1 1 0
0
BRG16
X 1 0 1
0
 2010 Microchip Technology Inc.
TX9D
DS41303G-page 237
PIC18F2XK20/4XK20
FIGURE 18-2:
EUSART RECEIVE BLOCK DIAGRAM
CREN
RX/DT pin
Baud Rate Generator
Data
Recovery
FOSC
BRG16
SPBRGH
SPBRG
Multiplier
x4
x16 x64
SYNC
1 X 0 0
0
BRGH
X 1 1 0
0
BRG16
X 1 0 1
0
Stop
RCIDL
RSR Register
MSb
Pin Buffer
and Control
+1
OERR
(8)
•••
7
1
LSb
0 START
RX9
÷n
n
FERR
RX9D
RCREG Register
FIFO
8
Data Bus
RCIF
RCIE
Interrupt
The operation of the EUSART module is controlled
through three registers:
• Transmit Status and Control (TXSTA)
• Receive Status and Control (RCSTA)
• Baud Rate Control (BAUDCON)
These registers are detailed in Register 18-1,
Register 18-2 and Register 18-3, respectively.
For all modes of EUSART operation, the TRIS control
bits corresponding to the RX/DT and TX/CK pins should
be set to ‘1’. The EUSART control will automatically
reconfigure the pin from input to output, as needed.
When the receiver or transmitter section is not enabled
then the corresponding RX or TX pin may be used for
general purpose input and output.
DS41303G-page 238
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
18.1
EUSART Asynchronous Mode
The EUSART transmits and receives data using the
standard non-return-to-zero (NRZ) format. NRZ is
implemented with two levels: a VOH mark state which
represents a ‘1’ data bit, and a VOL space state which
represents a ‘0’ data bit. NRZ refers to the fact that
consecutively transmitted data bits of the same value
stay at the output level of that bit without returning to a
neutral level between each bit transmission. An NRZ
transmission port idles in the mark state. Each character
transmission consists of one Start bit followed by eight
or nine data bits and is always terminated by one or
more Stop bits. The Start bit is always a space and the
Stop bits are always marks. The most common data
format is 8 bits. Each transmitted bit persists for a period
of 1/(Baud Rate). An on-chip dedicated 8-bit/16-bit Baud
Rate Generator is used to derive standard baud rate
frequencies from the system oscillator. See Table 18-5
for examples of baud rate configurations.
18.1.1.2
Transmitting Data
A transmission is initiated by writing a character to the
TXREG register. If this is the first character, or the
previous character has been completely flushed from
the TSR, the data in the TXREG is immediately
transferred to the TSR register. If the TSR still contains
all or part of a previous character, the new character
data is held in the TXREG until the Stop bit of the
previous character has been transmitted. The pending
character in the TXREG is then transferred to the TSR
in one TCY immediately following the Stop bit
transmission. The transmission of the Start bit, data bits
and Stop bit sequence commences immediately
following the transfer of the data to the TSR from the
TXREG.
18.1.1.3
Transmit Data Polarity
The EUSART transmits and receives the LSb first. The
EUSART’s transmitter and receiver are functionally
independent, but share the same data format and baud
rate. Parity is not supported by the hardware, but can
be implemented in software and stored as the ninth
data bit.
The polarity of the transmit data can be controlled with
the CKTXP bit of the BAUDCON register. The default
state of this bit is ‘0’ which selects high true transmit
idle and data bits. Setting the CKTXP bit to ‘1’ will invert
the transmit data resulting in low true idle and data bits.
The CKTXP bit controls transmit data polarity only in
Asynchronous mode. In Synchronous mode the
CKTXP bit has a different function.
18.1.1
18.1.1.4
EUSART ASYNCHRONOUS
TRANSMITTER
The EUSART transmitter block diagram is shown in
Figure 18-1. The heart of the transmitter is the serial
Transmit Shift Register (TSR), which is not directly
accessible by software. The TSR obtains its data from
the transmit buffer, which is the TXREG register.
18.1.1.1
Enabling the Transmitter
The EUSART transmitter is enabled for asynchronous
operations by configuring the following three control
bits:
• TXEN = 1
• SYNC = 0
• SPEN = 1
All other EUSART control bits are assumed to be in
their default state.
Setting the TXEN bit of the TXSTA register enables the
transmitter circuitry of the EUSART. Clearing the SYNC
bit of the TXSTA register configures the EUSART for
asynchronous operation. Setting the SPEN bit of the
RCSTA register enables the EUSART and
automatically configures the TX/CK I/O pin as an output.
If the TX/CK pin is shared with an analog peripheral the
analog I/O function must be disabled by clearing the
corresponding ANSEL bit.
Note:
Transmit Interrupt Flag
The TXIF interrupt flag bit of the PIR1 register is set
whenever the EUSART transmitter is enabled and no
character is being held for transmission in the TXREG.
In other words, the TXIF bit is only clear when the TSR
is busy with a character and a new character has been
queued for transmission in the TXREG. The TXIF flag
bit is not cleared immediately upon writing TXREG.
TXIF becomes valid in the second instruction cycle
following the write execution. Polling TXIF immediately
following the TXREG write will return invalid results. The
TXIF bit is read-only, it cannot be set or cleared by
software.
The TXIF interrupt can be enabled by setting the TXIE
interrupt enable bit of the PIE1 register. However, the
TXIF flag bit will be set whenever the TXREG is empty,
regardless of the state of TXIE enable bit.
To use interrupts when transmitting data, set the TXIE
bit only when there is more data to send. Clear the
TXIE interrupt enable bit upon writing the last character
of the transmission to the TXREG.
The TXIF transmitter interrupt flag is set
when the TXEN enable bit is set.
 2010 Microchip Technology Inc.
DS41303G-page 239
PIC18F2XK20/4XK20
18.1.1.5
TSR Status
18.1.1.7
The TRMT bit of the TXSTA register indicates the
status of the TSR register. This is a read-only bit. The
TRMT bit is set when the TSR register is empty and is
cleared when a character is transferred to the TSR
register from the TXREG. The TRMT bit remains clear
until all bits have been shifted out of the TSR register.
No interrupt logic is tied to this bit, so the user needs to
poll this bit to determine the TSR status.
Note:
18.1.1.6
1.
2.
3.
4.
The TSR register is not mapped in data
memory, so it is not available to the user.
Transmitting 9-Bit Characters
5.
The EUSART supports 9-bit character transmissions.
When the TX9 bit of the TXSTA register is set the
EUSART will shift 9 bits out for each character transmitted. The TX9D bit of the TXSTA register is the ninth,
and Most Significant, data bit. When transmitting 9-bit
data, the TX9D data bit must be written before writing
the 8 Least Significant bits into the TXREG. All nine bits
of data will be transferred to the TSR shift register
immediately after the TXREG is written.
A special 9-bit Address mode is available for use with
multiple receivers. See Section 18.1.2.8 “Address
Detection” for more information on the Address mode.
FIGURE 18-3:
6.
7.
8.
9.
Asynchronous Transmission Set-up:
Initialize the SPBRGH:SPBRG register pair and
the BRGH and BRG16 bits to achieve the desired
baud rate (see Section 18.3 “EUSART Baud
Rate Generator (BRG)”).
Set the RX/DT and TX/CK TRIS controls to ‘1’.
Enable the asynchronous serial port by clearing
the SYNC bit and setting the SPEN bit.
If 9-bit transmission is desired, set the TX9 control bit. A set ninth data bit will indicate that the 8
Least Significant data bits are an address when
the receiver is set for address detection.
Set the CKTXP control bit if inverted transmit
data polarity is desired.
Enable the transmission by setting the TXEN
control bit. This will cause the TXIF interrupt bit
to be set.
If interrupts are desired, set the TXIE interrupt
enable bit. An interrupt will occur immediately
provided that the GIE and PEIE bits of the INTCON register are also set.
If 9-bit transmission is selected, the ninth bit
should be loaded into the TX9D data bit.
Load 8-bit data into the TXREG register. This
will start the transmission.
ASYNCHRONOUS TRANSMISSION
Write to TXREG
BRG Output
(Shift Clock)
RC4/C2OUT/TX/CK
pin
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
DS41303G-page 240
Word 1
Start bit
bit 0
bit 1
bit 7/8
Stop bit
Word 1
1 TCY
Word 1
Transmit Shift Reg
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 18-4:
ASYNCHRONOUS TRANSMISSION (BACK-TO-BACK)
Write to TXREG
Word 1
BRG Output
(Shift Clock)
RC4/C2OUT/TX/CK
pin
Word 2
Start bit
bit 0
bit 1
Word 1
1 TCY
TXIF bit
(Interrupt Reg. Flag)
bit 7/8
Stop bit
Start bit
bit 0
Word 2
1 TCY
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Note:
Word 2
Transmit Shift Reg
This timing diagram shows two consecutive transmissions.
TABLE 18-1:
Name
Word 1
Transmit Shift Reg
REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
61
RCSTA
TXREG
TXSTA
EUSART Transmit Register
61
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
61
BAUDCON
ABDOVF
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
61
SPBRGH
EUSART Baud Rate Generator Register, High Byte
61
SPBRG
EUSART Baud Rate Generator Register, Low Byte
61
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous transmission.
Note 1: Reserved in PIC18F2XK20 devices; always maintain these bits clear.
 2010 Microchip Technology Inc.
DS41303G-page 241
PIC18F2XK20/4XK20
18.1.2
EUSART ASYNCHRONOUS
RECEIVER
The Asynchronous mode would typically be used in
RS-232 systems. The receiver block diagram is shown
in Figure 18-2. The data is received on the RX/DT pin
and drives the data recovery block. The data recovery
block is actually a high-speed shifter operating at 16
times the baud rate, whereas the serial Receive Shift
Register (RSR) operates at the bit rate. When all 8 or 9
bits of the character have been shifted in, they are
immediately transferred to a two character
First-In-First-Out (FIFO) memory. The FIFO buffering
allows reception of two complete characters and the
start of a third character before software must start
servicing the EUSART receiver. The FIFO and RSR
registers are not directly accessible by software.
Access to the received data is via the RCREG register.
18.1.2.1
Enabling the Receiver
The EUSART receiver is enabled for asynchronous
operation by configuring the following three control bits:
• CREN = 1
• SYNC = 0
• SPEN = 1
All other EUSART control bits are assumed to be in
their default state.
Setting the CREN bit of the RCSTA register enables the
receiver circuitry of the EUSART. Clearing the SYNC bit
of the TXSTA register configures the EUSART for
asynchronous operation. Setting the SPEN bit of the
RCSTA register enables the EUSART. The RX/DT I/O
pin must be configured as an input by setting the
corresponding TRIS control bit. If the RX/DT pin is
shared with an analog peripheral the analog I/O function
must be disabled by clearing the corresponding ANSEL
bit.
DS41303G-page 242
18.1.2.2
Receiving Data
The receiver data recovery circuit initiates character
reception on the falling edge of the first bit. The first bit,
also known as the Start bit, is always a zero. The data
recovery circuit counts one-half bit time to the center of
the Start bit and verifies that the bit is still a zero. If it is
not a zero then the data recovery circuit aborts
character reception, without generating an error, and
resumes looking for the falling edge of the Start bit. If
the Start bit zero verification succeeds then the data
recovery circuit counts a full bit time to the center of the
next bit. The bit is then sampled by a majority detect
circuit and the resulting ‘0’ or ‘1’ is shifted into the RSR.
This repeats until all data bits have been sampled and
shifted into the RSR. One final bit time is measured and
the level sampled. This is the Stop bit, which is always
a ‘1’. If the data recovery circuit samples a ‘0’ in the
Stop bit position then a framing error is set for this
character, otherwise the framing error is cleared for this
character. See Section 18.1.2.5 “Receive Framing
Error” for more information on framing errors.
Immediately after all data bits and the Stop bit have
been received, the character in the RSR is transferred
to the EUSART receive FIFO and the RCIF interrupt
flag bit of the PIR1 register is set. The top character in
the FIFO is transferred out of the FIFO by reading the
RCREG register.
Note:
18.1.2.3
If the receive FIFO is overrun, no additional
characters will be received until the overrun
condition is cleared. See Section 18.1.2.6
“Receive Overrun Error” for more
information on overrun errors.
Receive Data Polarity
The polarity of the receive data can be controlled with
the DTRXP bit of the BAUDCON register. The default
state of this bit is ‘0’ which selects high true receive idle
and data bits. Setting the DTRXP bit to ‘1’ will invert the
receive data resulting in low true idle and data bits. The
DTRXP bit controls receive data polarity only in Asynchronous mode. In synchronous mode the DTRXP bit
has a different function.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
18.1.2.4
Receive Interrupts
The RCIF interrupt flag bit of the PIR1 register is set
whenever the EUSART receiver is enabled and there is
an unread character in the receive FIFO. The RCIF
interrupt flag bit is read-only, it cannot be set or cleared
by software.
RCIF interrupts are enabled by setting the following
bits:
• RCIE interrupt enable bit of the PIE1 register
• PEIE peripheral interrupt enable bit of the INTCON register
• GIE global interrupt enable bit of the INTCON
register
The RCIF interrupt flag bit will be set when there is an
unread character in the FIFO, regardless of the state of
interrupt enable bits.
18.1.2.5
Receive Framing Error
Each character in the receive FIFO buffer has a
corresponding framing error Status bit. A framing error
indicates that a Stop bit was not seen at the expected
time. The framing error status is accessed via the
FERR bit of the RCSTA register. The FERR bit
represents the status of the top unread character in the
receive FIFO. Therefore, the FERR bit must be read
before reading the RCREG.
The FERR bit is read-only and only applies to the top
unread character in the receive FIFO. A framing error
(FERR = 1) does not preclude reception of additional
characters. It is not necessary to clear the FERR bit.
Reading the next character from the FIFO buffer will
advance the FIFO to the next character and the next
corresponding framing error.
18.1.2.7
Receiving 9-bit Characters
The EUSART supports 9-bit character reception. When
the RX9 bit of the RCSTA register is set, the EUSART
will shift 9 bits into the RSR for each character
received. The RX9D bit of the RCSTA register is the
ninth and Most Significant data bit of the top unread
character in the receive FIFO. When reading 9-bit data
from the receive FIFO buffer, the RX9D data bit must
be read before reading the 8 Least Significant bits from
the RCREG.
18.1.2.8
Address Detection
A special Address Detection mode is available for use
when multiple receivers share the same transmission
line, such as in RS-485 systems. Address detection is
enabled by setting the ADDEN bit of the RCSTA
register.
Address detection requires 9-bit character reception.
When address detection is enabled, only characters
with the ninth data bit set will be transferred to the
receive FIFO buffer, thereby setting the RCIF interrupt
bit. All other characters will be ignored.
Upon receiving an address character, user software
determines if the address matches its own. Upon
address match, user software must disable address
detection by clearing the ADDEN bit before the next
Stop bit occurs. When user software detects the end of
the message, determined by the message protocol
used, software places the receiver back into the
Address Detection mode by setting the ADDEN bit.
The FERR bit can be forced clear by clearing the SPEN
bit of the RCSTA register which resets the EUSART.
Clearing the CREN bit of the RCSTA register does not
affect the FERR bit. A framing error by itself does not
generate an interrupt.
Note:
18.1.2.6
If all receive characters in the receive
FIFO have framing errors, repeated reads
of the RCREG will not clear the FERR bit.
Receive Overrun Error
The receive FIFO buffer can hold two characters. An
overrun error will be generated If a third character, in its
entirety, is received before the FIFO is accessed. When
this happens the OERR bit of the RCSTA register is
set. The characters already in the FIFO buffer can be
read but no additional characters will be received until
the error is cleared. The error must be cleared by either
clearing the CREN bit of the RCSTA register or by
resetting the EUSART by clearing the SPEN bit of the
RCSTA register.
 2010 Microchip Technology Inc.
DS41303G-page 243
PIC18F2XK20/4XK20
18.1.2.9
Asynchronous Reception Set-up:
1.
Initialize the SPBRGH:SPBRG register pair and
the BRGH and BRG16 bits to achieve the
desired baud rate (see Section 18.3 “EUSART
Baud Rate Generator (BRG)”).
2. Set the RX/DT and TX/CK TRIS controls to ‘1’.
3. Enable the serial port by setting the SPEN bit
and the RX/DT pin TRIS bit. The SYNC bit must
be clear for asynchronous operation.
4. If interrupts are desired, set the RCIE interrupt
enable bit and set the GIE and PEIE bits of the
INTCON register.
5. If 9-bit reception is desired, set the RX9 bit.
6. Set the DTRXP if inverted receive polarity is
desired.
7. Enable reception by setting the CREN bit.
8. The RCIF interrupt flag bit will be set when a
character is transferred from the RSR to the
receive buffer. An interrupt will be generated if
the RCIE interrupt enable bit was also set.
9. Read the RCSTA register to get the error flags
and, if 9-bit data reception is enabled, the ninth
data bit.
10. Get the received 8 Least Significant data bits
from the receive buffer by reading the RCREG
register.
11. If an overrun occurred, clear the OERR flag by
clearing the CREN receiver enable bit.
18.1.2.10
This mode would typically be used in RS-485 systems.
To set up an Asynchronous Reception with Address
Detect Enable:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
DS41303G-page 244
9-bit Address Detection Mode Set-up
Initialize the SPBRGH, SPBRG register pair and
the BRGH and BRG16 bits to achieve the
desired baud rate (see Section 18.3 “EUSART
Baud Rate Generator (BRG)”).
Set the RX/DT and TX/CK TRIS controls to ‘1’.
Enable the serial port by setting the SPEN bit.
The SYNC bit must be clear for asynchronous
operation.
If interrupts are desired, set the RCIE interrupt
enable bit and set the GIE and PEIE bits of the
INTCON register.
Enable 9-bit reception by setting the RX9 bit.
Enable address detection by setting the ADDEN
bit.
Set the DTRXP if inverted receive polarity is
desired.
Enable reception by setting the CREN bit.
The RCIF interrupt flag bit will be set when a
character with the ninth bit set is transferred
from the RSR to the receive buffer. An interrupt
will be generated if the RCIE interrupt enable bit
was also set.
Read the RCSTA register to get the error flags.
The ninth data bit will always be set.
Get the received 8 Least Significant data bits
from the receive buffer by reading the RCREG
register. Software determines if this is the
device’s address.
If an overrun occurred, clear the OERR flag by
clearing the CREN receiver enable bit.
If the device has been addressed, clear the
ADDEN bit to allow all received data into the
receive buffer and generate interrupts.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 18-5:
ASYNCHRONOUS RECEPTION
Start
bit
bit 0
RX/DT pin
bit 7/8 Stop
bit
bit 1
Rcv Shift
Reg
Rcv Buffer Reg
Start
bit
bit 0
Start
bit
bit 7/8 Stop
bit
Word 2
RCREG
Word 1
RCREG
RCIDL
bit 7/8 Stop
bit
Read Rcv
Buffer Reg
RCREG
RCIF
(Interrupt Flag)
OERR bit
CREN
Note:
This timing diagram shows three words appearing on the RX input. The RCREG (receive buffer) is read after the third word,
causing the OERR (overrun) bit to be set.
TABLE 18-2:
Name
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
RCSTA
RCREG
EUSART Receive Register
61
61
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
62
TXSTA
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
61
BAUDCON
ABDOVF
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
SPBRGH
EUSART Baud Rate Generator Register, High Byte
61
SPBRG
EUSART Baud Rate Generator Register, Low Byte
61
61
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.
Note 1: Reserved in PIC18F2XK20 devices; always maintain these bits clear.
 2010 Microchip Technology Inc.
DS41303G-page 245
PIC18F2XK20/4XK20
18.2
Clock Accuracy with
Asynchronous Operation
The factory calibrates the internal oscillator block output (HFINTOSC). However, the HFINTOSC frequency
may drift as VDD or temperature changes, and this
directly affects the asynchronous baud rate. Two methods may be used to adjust the baud rate clock, but both
require a reference clock source of some kind.
REGISTER 18-1:
The first (preferred) method uses the OSCTUNE
register to adjust the HFINTOSC output. Adjusting the
value in the OSCTUNE register allows for fine resolution
changes to the system clock source. See Section 2.5
“Internal Clock Modes” for more information.
The other method adjusts the value in the Baud Rate
Generator. This can be done automatically with the
Auto-Baud Detect feature (see Section 18.3.1
“Auto-Baud Detect”). There may not be fine enough
resolution when adjusting the Baud Rate Generator to
compensate for a gradual change in the peripheral
clock frequency.
TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R-1
R/W-0
CSRC
TX9
TXEN(1)
SYNC
SENDB
BRGH
TRMT
TX9D
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
CSRC: Clock Source Select bit
Asynchronous mode:
Don’t care
Synchronous mode:
1 = Master mode (clock generated internally from BRG)
0 = Slave mode (clock from external source)
bit 6
TX9: 9-bit Transmit Enable bit
1 = Selects 9-bit transmission
0 = Selects 8-bit transmission
bit 5
TXEN: Transmit Enable bit(1)
1 = Transmit enabled
0 = Transmit disabled
bit 4
SYNC: EUSART Mode Select bit
1 = Synchronous mode
0 = Asynchronous mode
bit 3
SENDB: Send Break Character bit
Asynchronous mode:
1 = Send Sync Break on next transmission (cleared by hardware upon completion)
0 = Sync Break transmission completed
Synchronous mode:
Don’t care
bit 2
BRGH: High Baud Rate Select bit
Asynchronous mode:
1 = High speed
0 = Low speed
Synchronous mode:
Unused in this mode
bit 1
TRMT: Transmit Shift Register Status bit
1 = TSR empty
0 = TSR full
bit 0
TX9D: Ninth bit of Transmit Data
Can be address/data bit or a parity bit.
Note 1:
SREN/CREN overrides TXEN in Sync mode.
DS41303G-page 246
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 18-2:
RCSTA: RECEIVE STATUS AND CONTROL REGISTER(1)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R-0
R-0
R-x
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
SPEN: Serial Port Enable bit
1 = Serial port enabled (configures RX/DT and TX/CK pins as serial port pins)
0 = Serial port disabled (held in Reset)
bit 6
RX9: 9-bit Receive Enable bit
1 = Selects 9-bit reception
0 = Selects 8-bit reception
bit 5
SREN: Single Receive Enable bit
Asynchronous mode:
Don’t care
Synchronous mode – Master:
1 = Enables single receive
0 = Disables single receive
This bit is cleared after reception is complete.
Synchronous mode – Slave
Don’t care
bit 4
CREN: Continuous Receive Enable bit
Asynchronous mode:
1 = Enables receiver
0 = Disables receiver
Synchronous mode:
1 = Enables continuous receive until enable bit CREN is cleared (CREN overrides SREN)
0 = Disables continuous receive
bit 3
ADDEN: Address Detect Enable bit
Asynchronous mode 9-bit (RX9 = 1):
1 = Enables address detection, enable interrupt and load the receive buffer when RSR<8> is set
0 = Disables address detection, all bytes are received and ninth bit can be used as parity bit
Asynchronous mode 8-bit (RX9 = 0):
Don’t care
bit 2
FERR: Framing Error bit
1 = Framing error (can be updated by reading RCREG register and receive next valid byte)
0 = No framing error
bit 1
OERR: Overrun Error bit
1 = Overrun error (can be cleared by clearing bit CREN)
0 = No overrun error
bit 0
RX9D: Ninth bit of Received Data
This can be address/data bit or a parity bit and must be calculated by user firmware.
 2010 Microchip Technology Inc.
DS41303G-page 247
PIC18F2XK20/4XK20
REGISTER 18-3:
BAUDCON: BAUD RATE CONTROL REGISTER
R/W-0
R-1
R/W-0
R/W-0
R/W-0
U-0
R/W-0
R/W-0
ABDOVF
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
ABDOVF: Auto-Baud Detect Overflow bit
Asynchronous mode:
1 = Auto-baud timer overflowed
0 = Auto-baud timer did not overflow
Synchronous mode:
Don’t care
bit 6
RCIDL: Receive Idle Flag bit
Asynchronous mode:
1 = Receiver is Idle
0 = Start bit has been detected and the receiver is active
Synchronous mode:
Don’t care
bit 5
DTRXP: Data/Receive Polarity Select bit
Asynchronous mode:
1 = Receive data (RX) is inverted (active-low)
0 = Receive data (RX) is not inverted (active-high)
Synchronous mode:
1 = Data (DT) is inverted (active-low)
0 = Data (DT) is not inverted (active-high)
bit 4
CKTXP: Clock/Transmit Polarity Select bit
Asynchronous mode:
1 = Idle state for transmit (TX) is low
0 = Idle state for transmit (TX) is high
Synchronous mode:
1 = Data changes on the falling edge of the clock and is sampled on the rising edge of the clock
0 = Data changes on the rising edge of the clock and is sampled on the falling edge of the clock
bit 3
BRG16: 16-bit Baud Rate Generator bit
1 = 16-bit Baud Rate Generator is used (SPBRGH:SPBRG)
0 = 8-bit Baud Rate Generator is used (SPBRG)
bit 2
Unimplemented: Read as ‘0’
bit 1
WUE: Wake-up Enable bit
Asynchronous mode:
1 = Receiver is waiting for a falling edge. No character will be received but RCIF will be set on the falling
edge. WUE will automatically clear on the rising edge.
0 = Receiver is operating normally
Synchronous mode:
Don’t care
bit 0
ABDEN: Auto-Baud Detect Enable bit
Asynchronous mode:
1 = Auto-Baud Detect mode is enabled (clears when auto-baud is complete)
0 = Auto-Baud Detect mode is disabled
Synchronous mode:
Don’t care
DS41303G-page 248
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
18.3
EUSART Baud Rate Generator
(BRG)
The Baud Rate Generator (BRG) is an 8-bit or 16-bit
timer that is dedicated to the support of both the
asynchronous and synchronous EUSART operation.
By default, the BRG operates in 8-bit mode. Setting the
BRG16 bit of the BAUDCON register selects 16-bit
mode.
If the system clock is changed during an active receive
operation, a receive error or data loss may result. To
avoid this problem, check the status of the RCIDL bit to
make sure that the receive operation is Idle before
changing the system clock.
EXAMPLE 18-1:
For a device with FOSC of 16 MHz, desired baud rate
of 9600, Asynchronous mode, 8-bit BRG:
The SPBRGH:SPBRG register pair determines the
period of the free running baud rate timer. In
Asynchronous mode the multiplier of the baud rate
period is determined by both the BRGH bit of the TXSTA
register and the BRG16 bit of the BAUDCON register. In
Synchronous mode, the BRGH bit is ignored.
F OS C
Desired Baud Rate = --------------------------------------------------------------------64  [SPBRGH:SPBRG] + 1 
Solving for SPBRGH:SPBRG:
FOSC
--------------------------------------------Desired Baud Rate
X = --------------------------------------------- – 1
64
Table 18-3 contains the formulas for determining the
baud rate. Example 18-1 provides a sample calculation
for determining the baud rate and baud rate error.
Typical baud rates and error values for various
asynchronous modes have been computed for your
convenience and are shown in Table 18-5. It may be
advantageous to use the high baud rate (BRGH = 1),
or the 16-bit BRG (BRG16 = 1) to reduce the baud rate
error. The 16-bit BRG mode is used to achieve slow
baud rates for fast oscillator frequencies.
16000000
-----------------------9600
= ------------------------ – 1
64
=  25.042  = 25
16000000
Calculated Baud Rate = --------------------------64  25 + 1 
= 9615
Writing a new value to the SPBRGH, SPBRG register
pair causes the BRG timer to be reset (or cleared). This
ensures that the BRG does not wait for a timer overflow
before outputting the new baud rate.
TABLE 18-3:
CALCULATING BAUD
RATE ERROR
Calc. Baud Rate – Desired Baud Rate
Error = -------------------------------------------------------------------------------------------Desired Baud Rate
 9615 – 9600 
= ---------------------------------- = 0.16%
9600
BAUD RATE FORMULAS
Configuration Bits
BRG/EUSART Mode
Baud Rate Formula
0
8-bit/Asynchronous
FOSC/[64 (n+1)]
0
1
8-bit/Asynchronous
0
1
0
16-bit/Asynchronous
0
1
1
16-bit/Asynchronous
1
0
x
8-bit/Synchronous
1
x
16-bit/Synchronous
SYNC
BRG16
BRGH
0
0
0
FOSC/[16 (n+1)]
1
Legend:
x = Don’t care, n = value of SPBRGH, SPBRG register pair
TABLE 18-4:
Name
FOSC/[4 (n+1)]
REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset Values
on page
TXSTA
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
61
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
61
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
61
BAUDCON ABDOVF
SPBRGH
EUSART Baud Rate Generator Register, High Byte
61
SPBRG
EUSART Baud Rate Generator Register, Low Byte
61
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the BRG.
 2010 Microchip Technology Inc.
DS41303G-page 249
PIC18F2XK20/4XK20
TABLE 18-5:
BAUD RATES FOR ASYNCHRONOUS MODES
SYNC = 0, BRGH = 0, BRG16 = 0
BAUD
RATE
FOSC = 64.000 MHz
FOSC = 18.432 MHz
FOSC = 16.000 MHz
FOSC = 11.0592 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
—
—
—
—
—
—
—
—
—
—
—
—
1200
—
—
—
1200
0.00
239
1202
0.16
207
1200
0.00
143
Actual
Rate
%
Error
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
2400
—
—
—
2400
0.00
119
2404
0.16
103
2400
0.00
71
9600
9615
0.16
103
9600
0.00
29
9615
0.16
25
9600
0.00
17
10417
10417
0.00
95
10286
-1.26
27
10417
0.00
23
10165
-2.42
16
19.2k
19.23k
0.16
51
19.20k
0.00
14
19.23k
0.16
12
19.20k
0.00
8
57.6k
58.82k
2.12
16
57.60k
0.00
7
—
—
—
57.60k
0.00
2
115.2k
111.11k
-3.55
8
—
—
—
—
—
—
—
—
—
SYNC = 0, BRGH = 0, BRG16 = 0
BAUD
RATE
FOSC = 8.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 4.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 3.6864 MHz
Actual
Rate
FOSC = 1.000 MHz
%
Error
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
—
—
—
300
0.16
207
300
0.00
191
300
0.16
51
1200
1202
0.16
103
1202
0.16
51
1200
0.00
47
1202
0.16
12
2400
2404
0.16
51
2404
0.16
25
2400
0.00
23
—
—
—
9600
9615
0.16
12
—
—
—
9600
0.00
5
—
—
—
10417
10417
0.00
11
10417
0.00
5
—
—
—
—
—
—
19.2k
—
—
—
—
—
—
19.20k
0.00
2
—
—
—
57.6k
—
—
—
—
—
—
57.60k
0.00
0
—
—
—
115.2k
—
—
—
—
—
—
—
—
—
—
—
—
SYNC = 0, BRGH = 1, BRG16 = 0
BAUD
RATE
FOSC = 64.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 18.432 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 16.000 MHz
Actual
Rate
%
Error
FOSC = 11.0592 MHz
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
—
—
—
—
—
—
—
—
—
—
—
—
1200
—
—
—
—
—
—
—
—
—
—
—
—
2400
—
—
—
—
—
—
—
—
—
—
—
—
9600
—
—
—
9600
0.00
119
9615
0.16
103
9600
0.00
71
10417
—
—
—
10378
-0.37
110
10417
0.00
95
10473
0.53
65
19.2k
19.23k
0.16
207
19.20k
0.00
59
19.23k
0.16
51
19.20k
0.00
35
57.6k
57.97k
0.64
68
57.60k
0.00
19
58.82k
2.12
16
57.60k
0.00
11
115.2k
114.29k
-0.79
34
115.2k
0.00
9
111.1k
-3.55
8
115.2k
0.00
5
DS41303G-page 250
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 18-5:
BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 1, BRG16 = 0
BAUD
RATE
FOSC = 8.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 4.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 3.6864 MHz
Actual
Rate
FOSC = 1.000 MHz
%
Error
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
1200
—
—
—
—
—
—
—
1202
—
0.16
—
207
—
1200
—
0.00
—
191
300
1202
0.16
0.16
207
51
2400
2404
0.16
207
2404
0.16
103
2400
0.00
95
2404
0.16
25
—
9600
9615
0.16
51
9615
0.16
25
9600
0.00
23
—
—
10417
10417
0.00
47
10417
0.00
23
10473
0.53
21
10417
0.00
5
19.2k
19231
0.16
25
19.23k
0.16
12
19.2k
0.00
11
—
—
—
57.6k
55556
-3.55
8
—
—
—
57.60k
0.00
3
—
—
—
115.2k
—
—
—
—
—
—
115.2k
0.00
1
—
—
—
SYNC = 0, BRGH = 0, BRG16 = 1
BAUD
RATE
FOSC = 64.000 MHz
Actual
Rate
FOSC = 18.432 MHz
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
FOSC = 16.000 MHz
Actual
Rate
FOSC = 11.0592 MHz
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
300
300.0
0.00
13332
300.0
0.00
3839
300.03
0.01
3332
300.0
0.00
2303
1200
1200.1
0.01
3332
1200
0.00
959
1200.5
0.04
832
1200
0.00
575
2400
2399
-0.02
1666
2400
0.00
479
2398
-0.08
416
2400
0.00
287
9600
9592
-0.08
416
9600
0.00
119
9615
0.16
103
9600
0.00
71
10417
10417
0.00
383
10378
-0.37
110
10417
0.00
95
10473
0.53
65
19.2k
19.23k
0.16
207
19.20k
0.00
59
19.23k
0.16
51
19.20k
0.00
35
57.6k
57.97k
0.64
68
57.60k
0.00
19
58.82k
2.12
16
57.60k
0.00
11
115.2k
114.29k
-0.79
34
115.2k
0.00
9
111.11k
-3.55
8
115.2k
0.00
5
SYNC = 0, BRGH = 0, BRG16 = 1
BAUD
RATE
FOSC = 8.000 MHz
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
FOSC = 4.000 MHz
Actual
Rate
FOSC = 3.6864 MHz
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
FOSC = 1.000 MHz
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
300
299.9
-0.02
1666
300.1
0.04
832
300.0
0.00
767
300.5
0.16
207
1200
1199
-0.08
416
1202
0.16
207
1200
0.00
191
1202
0.16
51
2400
2404
0.16
207
2404
0.16
103
2400
0.00
95
2404
0.16
25
9600
9615
0.16
51
9615
0.16
25
9600
0.00
23
—
—
—
10417
10417
0.00
47
10417
0.00
23
10473
0.53
21
10417
0.00
5
19.2k
19.23k
0.16
25
19.23k
0.16
12
19.20k
0.00
11
—
—
—
57.6k
55556
-3.55
8
—
—
—
57.60k
0.00
3
—
—
—
115.2k
—
—
—
—
—
—
115.2k
0.00
1
—
—
—
 2010 Microchip Technology Inc.
DS41303G-page 251
PIC18F2XK20/4XK20
TABLE 18-5:
BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1
BAUD
RATE
FOSC = 64.000 MHz
FOSC = 18.432 MHz
FOSC = 16.000 MHz
FOSC = 11.0592 MHz
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
300
1200
300
1200
0.00
0.00
53332
13332
300.0
1200
0.00
0.00
15359
3839
300.0
1200.1
0.00
0.01
13332
3332
300.0
1200
0.00
0.00
9215
2303
2400
2400
0.00
6666
2400
0.00
1919
2399.5
-0.02
1666
2400
0.00
1151
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
9600
9598.1
-0.02
1666
9600
0.00
479
9592
-0.08
416
9600
0.00
287
10417
10417
0.00
1535
10425
0.08
441
10417
0.00
383
10433
0.16
264
19.2k
19.21k
0.04
832
19.20k
0.00
239
19.23k
0.16
207
19.20k
0.00
143
57.6k
57.55k
-0.08
277
57.60k
0.00
79
57.97k
0.64
68
57.60k
0.00
47
115.2k
115.11k
-0.08
138
115.2k
0.00
39
114.29k
-0.79
34
115.2k
0.00
23
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1
BAUD
RATE
FOSC = 8.000 MHz
Actual
Rate
FOSC = 4.000 MHz
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
FOSC = 3.6864 MHz
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
FOSC = 1.000 MHz
%
Error
SPBRGH
:SPBRG
(decimal)
Actual
Rate
%
Error
SPBRGH
:SPBRG
(decimal)
832
300
300.0
0.00
6666
300.0
0.01
3332
300.0
0.00
3071
300.1
0.04
1200
1200
-0.02
1666
1200
0.04
832
1200
0.00
767
1202
0.16
207
2400
2401
0.04
832
2398
0.08
416
2400
0.00
383
2404
0.16
103
9600
9615
0.16
207
9615
0.16
103
9600
0.00
95
9615
0.16
25
10417
10417
0.00
191
10417
0.00
95
10473
0.53
87
10417
0.00
23
19.2k
19.23k
0.16
103
19.23k
0.16
51
19.20k
0.00
47
19.23k
0.16
12
57.6k
57.14k
-0.79
34
58.82k
2.12
16
57.60k
0.00
15
—
—
—
115.2k
117.6k
2.12
16
111.1k
-3.55
8
115.2k
0.00
7
—
—
—
DS41303G-page 252
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
18.3.1
AUTO-BAUD DETECT
The EUSART module supports automatic detection
and calibration of the baud rate.
and SPBRG registers are clocked at 1/8th the BRG
base clock rate. The resulting byte measurement is the
average bit time when clocked at full speed.
Note 1: If the WUE bit is set with the ABDEN bit,
auto-baud detection will occur on the byte
following the Break character (see
Section 18.3.3
“Auto-Wake-up
on
Break”).
In the Auto-Baud Detect (ABD) mode, the clock to the
BRG is reversed. Rather than the BRG clocking the
incoming RX signal, the RX signal is timing the BRG.
The Baud Rate Generator is used to time the period of
a received 55h (ASCII “U”) which is the Sync character
for the LIN bus. The unique feature of this character is
that it has five rising edges including the Stop bit edge.
Setting the ABDEN bit of the BAUDCON register starts
the auto-baud calibration sequence (Figure 18.3.2).
While the ABD sequence takes place, the EUSART
state machine is held in Idle. On the first rising edge of
the receive line, after the Start bit, the SPBRG begins
counting up using the BRG counter clock as shown in
Table 18-6. The fifth rising edge will occur on the RX pin
at the end of the eighth bit period. At that time, an
accumulated value totaling the proper BRG period is
left in the SPBRGH:SPBRG register pair, the ABDEN
bit is automatically cleared, and the RCIF interrupt flag
is set. A read operation on the RCREG needs to be
performed to clear the RCIF interrupt. RCREG content
should be discarded. When calibrating for modes that
do not use the SPBRGH register the user can verify
that the SPBRG register did not overflow by checking
for 00h in the SPBRGH register.
2: It is up to the user to determine that the
incoming character baud rate is within the
range of the selected BRG clock source.
Some combinations of oscillator frequency
and EUSART baud rates are not possible.
3: During the auto-baud process, the
auto-baud counter starts counting at 1.
Upon completion of the auto-baud
sequence, to achieve maximum accuracy,
subtract 1 from the SPBRGH:SPBRG
register pair.
TABLE 18-6:
The BRG auto-baud clock is determined by the BRG16
and BRGH bits as shown in Table 18-6. During ABD,
both the SPBRGH and SPBRG registers are used as a
16-bit counter, independent of the BRG16 bit setting.
While calibrating the baud rate period, the SPBRGH
FIGURE 18-6:
BRG16
BRGH
BRG Base
Clock
BRG ABD
Clock
0
0
FOSC/64
FOSC/512
0
1
FOSC/16
FOSC/128
1
0
FOSC/16
FOSC/128
1
1
FOSC/4
FOSC/32
Note:
During the ABD sequence, SPBRG and
SPBRGH registers are both used as a 16-bit
counter, independent of BRG16 setting.
AUTOMATIC BAUD RATE CALIBRATION
XXXXh
BRG Value
BRG COUNTER CLOCK RATES
RX pin
0000h
001Ch
Start
Edge #1
bit 1
bit 0
Edge #2
bit 3
bit 2
Edge #3
bit 5
bit 4
Edge #4
bit 7
bit 6
Edge #5
Stop bit
BRG Clock
Auto Cleared
Set by User
ABDEN bit
RCIDL
RCIF bit
(Interrupt)
Read
RCREG
SPBRG
XXh
1Ch
SPBRGH
XXh
00h
Note 1:
The ABD sequence requires the EUSART module to be configured in Asynchronous mode.
 2010 Microchip Technology Inc.
DS41303G-page 253
PIC18F2XK20/4XK20
18.3.2
AUTO-BAUD OVERFLOW
18.3.3.1
Special Considerations
During the course of automatic baud detection, the
ABDOVF bit of the BAUDCON register will be set if the
baud rate counter overflows before the fifth rising edge
is detected on the RX pin. The ABDOVF bit indicates
that the counter has exceeded the maximum count that
can fit in the 16 bits of the SPBRGH:SPBRG register
pair. After the ABDOVF has been set, the counter continues to count until the fifth rising edge is detected on
the RX pin. Upon detecting the fifth RX edge, the hardware will set the RCIF interrupt flag and clear the
ABDEN bit of the BAUDCON register. The RCIF flag
can be subsequently cleared by reading the RCREG.
The ABDOVF flag can be cleared by software directly.
Break Character
To terminate the auto-baud process before the RCIF
flag is set, clear the ABDEN bit then clear the ABDOVF
bit. The ABDOVF bit will remain set if the ABDEN bit is
not cleared first.
Therefore, the initial character in the transmission must
be all ‘0’s. This must be 10 or more bit times, 13-bit
times recommended for LIN bus, or any number of bit
times for standard RS-232 devices.
18.3.3
AUTO-WAKE-UP ON BREAK
During Sleep mode, all clocks to the EUSART are
suspended. Because of this, the Baud Rate Generator
is inactive and a proper character reception cannot be
performed. The Auto-Wake-up feature allows the
controller to wake-up due to activity on the RX/DT line.
This feature is available only in Asynchronous mode.
The Auto-Wake-up feature is enabled by setting the
WUE bit of the BAUDCON register. Once set, the normal
receive sequence on RX/DT is disabled, and the
EUSART remains in an Idle state, monitoring for a
wake-up event independent of the CPU mode. A
wake-up event consists of a high-to-low transition on the
RX/DT line. (This coincides with the start of a Sync Break
or a wake-up signal character for the LIN protocol.)
The EUSART module generates an RCIF interrupt
coincident with the wake-up event. The interrupt is
generated synchronously to the Q clocks in normal CPU
operating modes (Figure 18-7), and asynchronously if
the device is in Sleep mode (Figure 18-8). The interrupt
condition is cleared by reading the RCREG register.
To avoid character errors or character fragments
during a wake-up event, the wake-up character must
be all zeros.
When the wake-up is enabled the function works
independent of the low time on the data stream. If the
WUE bit is set and a valid non-zero character is
received, the low time from the Start bit to the first rising
edge will be interpreted as the wake-up event. The
remaining bits in the character will be received as a
fragmented character and subsequent characters can
result in framing or overrun errors.
Oscillator Startup Time
Oscillator start-up time must be considered, especially
in applications using oscillators with longer start-up
intervals (i.e., LP, XT or HS/PLL mode). The Sync
Break (or wake-up signal) character must be of
sufficient length, and be followed by a sufficient
interval, to allow enough time for the selected oscillator
to start and provide proper initialization of the EUSART.
WUE Bit
The wake-up event causes a receive interrupt by
setting the RCIF bit. The WUE bit is cleared by
hardware by a rising edge on RX/DT. The interrupt
condition is then cleared by software by reading the
RCREG register and discarding its contents.
To ensure that no actual data is lost, check the RCIDL
bit to verify that a receive operation is not in process
before setting the WUE bit. If a receive operation is not
occurring, the WUE bit may then be set just prior to
entering the Sleep mode.
The WUE bit is automatically cleared by the low-to-high
transition on the RX line at the end of the Break. This
signals to the user that the Break event is over. At this
point, the EUSART module is in Idle mode waiting to
receive the next character.
DS41303G-page 254
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 18-7:
AUTO-WAKE-UP BIT (WUE) TIMING DURING NORMAL OPERATION
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
OSC1
Auto Cleared
Bit set by user
WUE bit
RX/DT Line
RCIF
Note 1:
Cleared due to User Read of RCREG
The EUSART remains in Idle while the WUE bit is set.
FIGURE 18-8:
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP
Q1Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1Q2 Q3 Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4
OSC1
Auto Cleared
Bit Set by User
WUE bit
RX/DT Line
Note 1
RCIF
Sleep Command Executed
Note 1:
2:
Sleep Ends
Cleared due to User Read of RCREG
If the wake-up event requires long oscillator warm-up time, the automatic clearing of the WUE bit can occur while the stposc signal is
still active. This sequence should not depend on the presence of Q clocks.
The EUSART remains in Idle while the WUE bit is set.
 2010 Microchip Technology Inc.
DS41303G-page 255
PIC18F2XK20/4XK20
18.3.4
BREAK CHARACTER SEQUENCE
The EUSART module has the capability of sending the
special Break character sequences that are required by
the LIN bus standard. A Break character consists of a
Start bit, followed by 12 ‘0’ bits and a Stop bit.
To send a Break character, set the SENDB and TXEN
bits of the TXSTA register. The Break character transmission is then initiated by a write to the TXREG. The
value of data written to TXREG will be ignored and all
‘0’s will be transmitted.
The SENDB bit is automatically reset by hardware after
the corresponding Stop bit is sent. This allows the user
to preload the transmit FIFO with the next transmit byte
following the Break character (typically, the Sync
character in the LIN specification).
The TRMT bit of the TXSTA register indicates when the
transmit operation is active or Idle, just as it does during
normal transmission. See Figure 18-9 for the timing of
the Break character sequence.
18.3.4.1
Break and Sync Transmit Sequence
The following sequence will start a message frame
header made up of a Break, followed by an auto-baud
Sync byte. This sequence is typical of a LIN bus
master.
1.
2.
3.
4.
5.
Configure the EUSART for the desired mode.
Set the TXEN and SENDB bits to enable the
Break sequence.
Load the TXREG with a dummy character to
initiate transmission (the value is ignored).
Write ‘55h’ to TXREG to load the Sync character
into the transmit FIFO buffer.
After the Break has been sent, the SENDB bit is
reset by hardware and the Sync character is
then transmitted.
FIGURE 18-9:
Write to TXREG
When the TXREG becomes empty, as indicated by the
TXIF, the next data byte can be written to TXREG.
18.3.5
RECEIVING A BREAK CHARACTER
The Enhanced EUSART module can receive a Break
character in two ways.
The first method to detect a Break character uses the
FERR bit of the RCSTA register and the Received data
as indicated by RCREG. The Baud Rate Generator is
assumed to have been initialized to the expected baud
rate.
A Break character has been received when;
• RCIF bit is set
• FERR bit is set
• RCREG = 00h
The second method uses the Auto-Wake-up feature
described in Section 18.3.3 “Auto-Wake-up on
Break”. By enabling this feature, the EUSART will
sample the next two transitions on RX/DT, cause an
RCIF interrupt, and receive the next data byte followed
by another interrupt.
Note that following a Break character, the user will
typically want to enable the Auto-Baud Detect feature.
For both methods, the user can set the ABDEN bit of
the BAUDCON register before placing the EUSART in
Sleep mode.
SEND BREAK CHARACTER SEQUENCE
Dummy Write
BRG Output
(Shift Clock)
TX (pin)
Start bit
bit 0
bit 1
bit 11
Stop bit
Break
TXIF bit
(Transmit
interrupt Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
SENDB Sampled Here
Auto Cleared
SENDB
(send Break
control bit)
DS41303G-page 256
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
18.4
EUSART Synchronous Mode
Synchronous serial communications are typically used
in systems with a single master and one or more
slaves. The master device contains the necessary
circuitry for baud rate generation and supplies the clock
for all devices in the system. Slave devices can take
advantage of the master clock by eliminating the
internal clock generation circuitry.
There are two signal lines in Synchronous mode: a
bidirectional data line and a clock line. Slaves use the
external clock supplied by the master to shift the serial
data into and out of their respective receive and
transmit shift registers. Since the data line is
bidirectional, synchronous operation is half-duplex
only. Half-duplex refers to the fact that master and
slave devices can receive and transmit data but not
both simultaneously. The EUSART can operate as
either a master or slave device.
Start and Stop bits are not used in synchronous
transmissions.
18.4.1
SYNCHRONOUS MASTER MODE
The following bits are used to configure the EUSART
for Synchronous Master operation:
•
•
•
•
•
SYNC = 1
CSRC = 1
SREN = 0 (for transmit); SREN = 1 (for receive)
CREN = 0 (for transmit); CREN = 1 (for receive)
SPEN = 1
Setting the SYNC bit of the TXSTA register configures
the device for synchronous operation. Setting the CSRC
bit of the TXSTA register configures the device as a
master. Clearing the SREN and CREN bits of the RCSTA
register ensures that the device is in the Transmit mode,
otherwise the device will be configured to receive. Setting
the SPEN bit of the RCSTA register enables the
EUSART. If the RX/DT or TX/CK pins are shared with an
analog peripheral the analog I/O functions must be
disabled by clearing the corresponding ANSEL bits.
18.4.1.2
Clock Polarity
A clock polarity option is provided for Microwire
compatibility. Clock polarity is selected with the CKTXP
bit of the BAUDCON register. Setting the CKTXP bit
sets the clock Idle state as high. When the CKTXP bit
is set, the data changes on the falling edge of each
clock and is sampled on the rising edge of each clock.
Clearing the CKTXP bit sets the Idle state as low. When
the CKTXP bit is cleared, the data changes on the
rising edge of each clock and is sampled on the falling
edge of each clock.
18.4.1.3
Synchronous Master Transmission
Data is transferred out of the device on the RX/DT pin.
The RX/DT and TX/CK pin output drivers are automatically enabled when the EUSART is configured for
synchronous master transmit operation.
A transmission is initiated by writing a character to the
TXREG register. If the TSR still contains all or part of a
previous character the new character data is held in the
TXREG until the last bit of the previous character has
been transmitted. If this is the first character, or the previous character has been completely flushed from the
TSR, the data in the TXREG is immediately transferred
to the TSR. The transmission of the character commences immediately following the transfer of the data
to the TSR from the TXREG.
Each data bit changes on the leading edge of the master clock and remains valid until the subsequent leading
clock edge.
Note:
18.4.1.4
The TSR register is not mapped in data
memory, so it is not available to the user.
Data Polarity
The polarity of the transmit and receive data can be
controlled with the DTRXP bit of the BAUDCON register. The default state of this bit is ‘0’ which selects high
true transmit and receive data. Setting the DTRXP bit
to ‘1’ will invert the data resulting in low true transmit
and receive data.
The TRIS bits corresponding to the RX/DT and TX/CK
pins should be set.
18.4.1.1
Master Clock
Synchronous data transfers use a separate clock line,
which is synchronous with the data. A device configured
as a master transmits the clock on the TX/CK line. The
TX/CK pin output driver is automatically enabled when
the EUSART is configured for synchronous transmit or
receive operation. Serial data bits change on the leading
edge to ensure they are valid at the trailing edge of each
clock. One clock cycle is generated for each data bit.
Only as many clock cycles are generated as there are
data bits.
 2010 Microchip Technology Inc.
DS41303G-page 257
PIC18F2XK20/4XK20
18.4.1.5
1.
2.
3.
Synchronous Master Transmission
Set-up:
4.
Initialize the SPBRGH, SPBRG register pair and
the BRGH and BRG16 bits to achieve the
desired baud rate (see Section 18.3 “EUSART
Baud Rate Generator (BRG)”).
Set the RX/DT and TX/CK TRIS controls to ‘1’.
Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC. Set the
TRIS bits corresponding to the RX/DT and
TX/CK I/O pins.
5.
6.
7.
FIGURE 18-10:
8.
9.
Disable Receive mode by clearing bits SREN
and CREN.
Enable Transmit mode by setting the TXEN bit.
If 9-bit transmission is desired, set the TX9 bit.
If interrupts are desired, set the TXIE, GIE and
PEIE interrupt enable bits.
If 9-bit transmission is selected, the ninth bit
should be loaded in the TX9D bit.
Start transmission by loading data to the
TXREG register.
SYNCHRONOUS TRANSMISSION
RX/DT
pin
bit 0
bit 1
Word 1
bit 2
bit 7
bit 0
bit 1
Word 2
bit 7
TX/CK pin
(SCKP = 0)
TX/CK pin
(SCKP = 1)
Write to
TXREG Reg
Write Word 1
Write Word 2
TXIF bit
(Interrupt Flag)
TRMT bit
TXEN bit
Note:
‘1’
‘1’
Sync Master mode, SPBRG = 0, continuous transmission of two 8-bit words.
FIGURE 18-11:
SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
RX/DT pin
bit 0
bit 1
bit 2
bit 6
bit 7
TX/CK pin
Write to
TXREG reg
TXIF bit
TRMT bit
TXEN bit
DS41303G-page 258
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 18-7:
Name
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
(1)
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
61
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
62
TXREG
EUSART Transmit Register
61
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
61
BAUDCON
ABDOVF
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
61
SPBRGH
EUSART Baud Rate Generator Register, High Byte
61
SPBRG
EUSART Baud Rate Generator Register, Low Byte
61
TXSTA
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.
Note 1: Reserved in PIC18F2XK20 devices; always maintain these bits clear.
 2010 Microchip Technology Inc.
DS41303G-page 259
PIC18F2XK20/4XK20
18.4.1.6
Synchronous Master Reception
Data is received at the RX/DT pin. The RX/DT pin
output driver must be disabled by setting the
corresponding TRIS bits when the EUSART is
configured for synchronous master receive operation.
In Synchronous mode, reception is enabled by setting
either the Single Receive Enable bit (SREN of the
RCSTA register) or the Continuous Receive Enable bit
(CREN of the RCSTA register).
When SREN is set and CREN is clear, only as many
clock cycles are generated as there are data bits in a
single character. The SREN bit is automatically cleared
at the completion of one character. When CREN is set,
clocks are continuously generated until CREN is
cleared. If CREN is cleared in the middle of a character
the CK clock stops immediately and the partial character is discarded. If SREN and CREN are both set, then
SREN is cleared at the completion of the first character
and CREN takes precedence.
To initiate reception, set either SREN or CREN. Data is
sampled at the RX/DT pin on the trailing edge of the
TX/CK clock pin and is shifted into the Receive Shift
Register (RSR). When a complete character is
received into the RSR, the RCIF bit is set and the
character is automatically transferred to the two
character receive FIFO. The Least Significant eight bits
of the top character in the receive FIFO are available in
RCREG. The RCIF bit remains set as long as there are
un-read characters in the receive FIFO.
18.4.1.7
Slave Clock
Synchronous data transfers use a separate clock line,
which is synchronous with the data. A device configured
as a slave receives the clock on the TX/CK line. The
TX/CK pin output driver must be disabled by setting the
associated TRIS bit when the device is configured for
synchronous slave transmit or receive operation. Serial
data bits change on the leading edge to ensure they are
valid at the trailing edge of each clock. One data bit is
transferred for each clock cycle. Only as many clock
cycles should be received as there are data bits.
DS41303G-page 260
18.4.1.8
Receive Overrun Error
The receive FIFO buffer can hold two characters. An
overrun error will be generated if a third character, in its
entirety, is received before RCREG is read to access
the FIFO. When this happens the OERR bit of the
RCSTA register is set. Previous data in the FIFO will
not be overwritten. The two characters in the FIFO
buffer can be read, however, no additional characters
will be received until the error is cleared. The OERR bit
can only be cleared by clearing the overrun condition.
If the overrun error occurred when the SREN bit is set
and CREN is clear then the error is cleared by reading
RCREG. If the overrun occurred when the CREN bit is
set then the error condition is cleared by either clearing
the CREN bit of the RCSTA register or by clearing the
SPEN bit which resets the EUSART.
18.4.1.9
Receiving 9-bit Characters
The EUSART supports 9-bit character reception. When
the RX9 bit of the RCSTA register is set the EUSART
will shift 9-bits into the RSR for each character
received. The RX9D bit of the RCSTA register is the
ninth, and Most Significant, data bit of the top unread
character in the receive FIFO. When reading 9-bit data
from the receive FIFO buffer, the RX9D data bit must
be read before reading the 8 Least Significant bits from
the RCREG.
18.4.1.10
Synchronous Master Reception
Set-up:
1.
Initialize the SPBRGH, SPBRG register pair for
the appropriate baud rate. Set or clear the
BRGH and BRG16 bits, as required, to achieve
the desired baud rate.
2. Set the RX/DT and TX/CK TRIS controls to ‘1’.
3. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC. Disable
RX/DT and TX/CK output drivers by setting the
corresponding TRIS bits.
4. Ensure bits CREN and SREN are clear.
5. If using interrupts, set the GIE and PEIE bits of
the INTCON register and set RCIE.
6. If 9-bit reception is desired, set bit RX9.
7. Start reception by setting the SREN bit or for
continuous reception, set the CREN bit.
8. Interrupt flag bit RCIF will be set when reception
of a character is complete. An interrupt will be
generated if the enable bit RCIE was set.
9. Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during reception.
10. Read the 8-bit received data by reading the
RCREG register.
11. If an overrun error occurs, clear the error by
either clearing the CREN bit of the RCSTA
register or by clearing the SPEN bit which resets
the EUSART.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 18-12:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
RX/DT
pin
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
TX/CK pin
(SCKP = 0)
TX/CK pin
(SCKP = 1)
Write to
bit SREN
SREN bit
CREN bit ‘0’
‘0’
RCIF bit
(Interrupt)
Read
RXREG
Note:
Timing diagram demonstrates Sync Master mode with bit SREN = 1 and bit BRGH = 0.
TABLE 18-8:
Name
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
RCSTA
RCREG
TXSTA
EUSART Receive Register
CSRC
BAUDCON ABDOVF
61
61
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
61
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
61
SPBRGH
EUSART Baud Rate Generator Register, High Byte
61
SPBRG
EUSART Baud Rate Generator Register, Low Byte
61
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master reception.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
 2010 Microchip Technology Inc.
DS41303G-page 261
PIC18F2XK20/4XK20
18.4.2
SYNCHRONOUS SLAVE MODE
The following bits are used to configure the EUSART
for Synchronous slave operation:
•
•
•
•
•
SYNC = 1
CSRC = 0
SREN = 0 (for transmit); SREN = 1 (for receive)
CREN = 0 (for transmit); CREN = 1 (for receive)
SPEN = 1
1.
2.
3.
4.
Setting the SYNC bit of the TXSTA register configures
the device for synchronous operation. Clearing the
CSRC bit of the TXSTA register configures the device as
a slave. Clearing the SREN and CREN bits of the RCSTA
register ensures that the device is in the Transmit mode,
otherwise the device will be configured to receive. Setting
the SPEN bit of the RCSTA register enables the
EUSART. If the RX/DT or TX/CK pins are shared with an
analog peripheral the analog I/O functions must be
disabled by clearing the corresponding ANSEL bits.
RX/DT and TX/CK pin output drivers must be disabled
by setting the corresponding TRIS bits.
18.4.2.1
If two words are written to the TXREG and then the
SLEEP instruction is executed, the following will occur:
EUSART Synchronous Slave
Transmit
The operation of the Synchronous Master and Slave
modes
are
identical
(see
Section 18.4.1.3
“Synchronous Master Transmission”), except in the
case of the Sleep mode.
5.
18.4.2.2
1.
2.
3.
4.
5.
6.
7.
8.
TABLE 18-9:
Name
The first character will immediately transfer to
the TSR register and transmit.
The second word will remain in TXREG register.
The TXIF bit will not be set.
After the first character has been shifted out of
TSR, the TXREG register will transfer the second
character to the TSR and the TXIF bit will now be
set.
If the PEIE and TXIE bits are set, the interrupt
will wake the device from Sleep and execute the
next instruction. If the GIE bit is also set, the
program will call the Interrupt Service Routine.
Synchronous Slave Transmission
Set-up:
Set the SYNC and SPEN bits and clear the
CSRC bit.
Set the RX/DT and TX/CK TRIS controls to ‘1’.
Clear the CREN and SREN bits.
If using interrupts, ensure that the GIE and PEIE
bits of the INTCON register are set and set the
TXIE bit.
If 9-bit transmission is desired, set the TX9 bit.
Enable transmission by setting the TXEN bit.
If 9-bit transmission is selected, insert the Most
Significant bit into the TX9D bit.
Start transmission by writing the Least
Significant 8 bits to the TXREG register.
REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
(1)
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
61
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
62
TXREG
EUSART Transmit Register
61
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
61
BAUDCON
ABDOVF
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
61
SPBRGH
EUSART Baud Rate Generator Register, High Byte
61
SPBRG
EUSART Baud Rate Generator Register, Low Byte
61
TXSTA
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.
Note 1: Reserved in PIC18F2XK20 devices; always maintain these bits clear.
DS41303G-page 262
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
18.4.2.3
EUSART Synchronous Slave
Reception
18.4.2.4
The operation of the Synchronous Master and Slave
modes is identical (Section 18.4.1.6 “Synchronous
Master Reception”), with the following exceptions:
• Sleep
• CREN bit is always set, therefore the receiver is
never Idle
• SREN bit, which is a “don't care” in Slave mode
A character may be received while in Sleep mode by
setting the CREN bit prior to entering Sleep. Once the
word is received, the RSR register will transfer the data
to the RCREG register. If the RCIE enable bit is set, the
interrupt generated will wake the device from Sleep
and execute the next instruction. If the GIE bit is also
set, the program will branch to the interrupt vector.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Synchronous Slave Reception
Set-up:
Set the SYNC and SPEN bits and clear the
CSRC bit.
Set the RX/DT and TX/CK TRIS controls to ‘1’.
If using interrupts, ensure that the GIE and PEIE
bits of the INTCON register are set and set the
RCIE bit.
If 9-bit reception is desired, set the RX9 bit.
Set the CREN bit to enable reception.
The RCIF bit will be set when reception is
complete. An interrupt will be generated if the
RCIE bit was set.
If 9-bit mode is enabled, retrieve the Most
Significant bit from the RX9D bit of the RCSTA
register.
Retrieve the 8 Least Significant bits from the
receive FIFO by reading the RCREG register.
If an overrun error occurs, clear the error by
either clearing the CREN bit of the RCSTA
register or by clearing the SPEN bit which resets
the EUSART.
TABLE 18-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
61
RCSTA
RCREG
EUSART Receive Register
61
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
61
BAUDCON
ABDOVF
RCIDL
DTRXP
CKTXP
BRG16
—
WUE
ABDEN
61
SPBRGH
EUSART Baud Rate Generator Register, High Byte
61
SPBRG
EUSART Baud Rate Generator Register, Low Byte
61
TXSTA
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave reception.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
 2010 Microchip Technology Inc.
DS41303G-page 263
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 264
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
19.0
ANALOG-TO-DIGITAL
CONVERTER (ADC) MODULE
The Analog-to-Digital Converter (ADC) allows
conversion of an analog input signal to a 10-bit binary
representation of that signal. This device uses analog
inputs, which are multiplexed into a single sample and
hold circuit. The output of the sample and hold is
connected to the input of the converter. The converter
generates a 10-bit binary result via successive
approximation and stores the conversion result into the
ADC result registers (ADRESL and ADRESH).
The ADC voltage reference is software selectable to
either VDD or a voltage applied to the external reference
pins.
The ADC can generate an interrupt upon completion of
a conversion. This interrupt can be used to wake-up the
device from Sleep.
Figure 19-1 shows the block diagram of the ADC.
FIGURE 19-1:
ADC BLOCK DIAGRAM
AVSS
VREF-
VCFG1 = 0
VCFG1 = 1
AVDD
VCFG0 = 0
VREF+
AN0
0000
AN1
0001
AN2
0010
AN3
0011
AN4
0100
AN5
0101
AN6
0110
AN7
0111
AN8
1000
AN9
1001
AN10
1010
AN11
1011
AN12
1100
Unused
1101
Unused
1110
VCFG0 = 1
ADC
10
GO/DONE
ADFM
0 = Left Justify
1 = Right Justify
ADON
10
VSS
ADRESH
ADRESL
1111
FVR
CHS<3:0>
 2010 Microchip Technology Inc.
DS41303G-page 265
PIC18F2XK20/4XK20
19.1
ADC Configuration
When configuring and using the ADC the following
functions must be considered:
•
•
•
•
•
•
Port configuration
Channel selection
ADC voltage reference selection
ADC conversion clock source
Interrupt control
Results formatting
19.1.1
PORT CONFIGURATION
The ANSEL, ANSELH, TRISA, TRISB and TRISE registers all configure the A/D port pins. Any port pin
needed as an analog input should have its corresponding ANSx bit set to disable the digital input buffer and
TRISx bit set to disable the digital output driver. If the
TRISx bit is cleared, the digital output level (VOH or
VOL) will be converted.
The A/D operation is independent of the state of the
ANSx bits and the TRIS bits.
Note 1: When reading the PORT register, all pins
with their corresponding ANSx bit set
read as cleared (a low level). However,
analog conversion of pins configured as
digital inputs (ANSx bit cleared and
TRISx bit set) will be accurately
converted.
19.1.2
Acquisition time is set with the ACQT<2:0> bits of the
ADCON2 register. Acquisition delays cover a range of
2 to 20 TAD. When the GO/DONE bit is set, the A/D
module continues to sample the input for the selected
acquisition time, then automatically begins a conversion. Since the acquisition time is programmed, there is
no need to wait for an acquisition time between selecting a channel and setting the GO/DONE bit.
Manual
acquisition
is
selected
when
ACQT<2:0> = 000. When the GO/DONE bit is set,
sampling is stopped and a conversion begins. The user
is responsible for ensuring the required acquisition time
has passed between selecting the desired input
channel and setting the GO/DONE bit. This option is
also the default Reset state of the ACQT<2:0> bits and
is compatible with devices that do not offer
programmable acquisition times.
In either case, when the conversion is completed, the
GO/DONE bit is cleared, the ADIF flag is set and the
A/D begins sampling the currently selected channel
again. When an acquisition time is programmed, there
is no indication of when the acquisition time ends and
the conversion begins.
19.1.5
3: The PBADEN bit in Configuration
Register 3H configures PORTB pins to
reset as analog or digital pins by
controlling how the bits in ANSELH are
reset.
•
•
•
•
•
•
•
CHANNEL SELECTION
When changing channels, a delay is required before
starting the next conversion. Refer to Section 19.2
“ADC Operation” for more information.
ADC VOLTAGE REFERENCE
The VCFG bits of the ADCON1 register provide
independent control of the positive and negative
voltage references. The positive voltage reference can
be either VDD or an external voltage source. Likewise,
the negative voltage reference can be either VSS or an
external voltage source.
DS41303G-page 266
SELECTING AND CONFIGURING
ACQUISITION TIME
The ADCON2 register allows the user to select an
acquisition time that occurs each time the GO/DONE
bit is set.
2: Analog levels on any pin with the corresponding ANSx bit cleared may cause the
digital input buffer to consume current out
of the device’s specification limits.
The CHS bits of the ADCON0 register determine which
channel is connected to the sample and hold circuit.
19.1.3
19.1.4
CONVERSION CLOCK
The source of the conversion clock is software selectable via the ADCS bits of the ADCON2 register. There
are seven possible clock options:
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/32
FOSC/64
FRC (dedicated internal oscillator)
The time to complete one bit conversion is defined as
TAD. One full 10-bit conversion requires 11 TAD periods
as shown in Figure 19-3.
For correct conversion, the appropriate TAD specification
must be met. See A/D conversion requirements in
Table 26-25 for more information. Table 19-1 gives
examples of appropriate ADC clock selections.
Note:
Unless using the FRC, any changes in the
system clock frequency will change the
ADC clock frequency, which may
adversely affect the ADC result.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
19.1.6
INTERRUPTS
This interrupt can be generated while the device is
operating or while in Sleep. If the device is in Sleep, the
interrupt will wake-up the device. Upon waking from
Sleep, the next instruction following the SLEEP
instruction is always executed. If the user is attempting
to wake-up from Sleep and resume in-line code
execution, the global interrupt must be disabled. If the
global interrupt is enabled, execution will switch to the
Interrupt Service Routine. Please see Section 19.1.6
“Interrupts” for more information.
The ADC module allows for the ability to generate an
interrupt upon completion of an Analog-to-Digital
Conversion. The ADC interrupt flag is the ADIF bit in
the PIR1 register. The ADC interrupt enable is the ADIE
bit in the PIE1 register. The ADIF bit must be cleared by
software.
Note:
The ADIF bit is set at the completion of
every conversion, regardless of whether
or not the ADC interrupt is enabled.
TABLE 19-1:
ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES
ADC Clock Period (TAD)
ADC Clock Source
ADCS<2:0>
FOSC/2
64 MHz
000
FOSC/4
100
31.25
ns(2)
62.5
ns(2)
ns(2)
FOSC/8
001
400
FOSC/16
101
250 ns(2)
FOSC/32
010
ns(2)
FOSC/64
110
FRC
Legend:
Note 1:
2:
3:
4:
19.1.7
Device Frequency (FOSC)
500
16 MHz
1.0 s
1-4
x11
4 MHz
250
ns(2)
1.0 s
4.0 s(3)
500
ns(2)
2.0 s
8.0 s(3)
1.0 s
4.0 s(3)
16.0 s(3)
2.0 s
s(3)
32.0 s(3)
16.0 s(3)
64.0 s(3)
s(1,4)
1-4 s(1,4)
8.0
4.0 s(3)
s(1,4)
2.0 s
125
500
1-4
s(1,4)
1-4
ns(2)
1 MHz
ns(2)
Shaded cells are outside of recommended range.
The FRC source has a typical TAD time of 1.7 s.
These values violate the minimum required TAD time.
For faster conversion times, the selection of another clock source is recommended.
When the device frequency is greater than 1 MHz, the FRC clock source is only recommended if the
conversion will be performed during Sleep.
RESULT FORMATTING
The 10-bit A/D conversion result can be supplied in two
formats, left justified or right justified. The ADFM bit of
the ADCON2 register controls the output format.
Figure 19-2 shows the two output formats.
FIGURE 19-2:
10-BIT A/D CONVERSION RESULT FORMAT
ADRESH
(ADFM = 0)
ADRESL
MSB
LSB
bit 7
bit 0
bit 7
10-bit A/D Result
(ADFM = 1)
bit 0
Unimplemented: Read as ‘0’
MSB
bit 7
Unimplemented: Read as ‘0’
 2010 Microchip Technology Inc.
LSB
bit 0
bit 7
bit 0
10-bit A/D Result
DS41303G-page 267
PIC18F2XK20/4XK20
19.2
ADC Operation
19.2.1
Figure 19-3 shows the operation of the A/D converter
after the GO bit has been set and the ACQT<2:0> bits
are cleared. A conversion is started after the following
instruction to allow entry into SLEEP mode before the
conversion begins.
STARTING A CONVERSION
To enable the ADC module, the ADON bit of the
ADCON0 register must be set to a ‘1’. Setting the GO/
DONE bit of the ADCON0 register to a ‘1’ will, depending on the ACQT bits of the ADCON2 register, either
immediately start the Analog-to-Digital conversion or
start an acquisition delay followed by the Analog-toDigital conversion.
FIGURE 19-3:
Figure 19-4 shows the operation of the A/D converter
after the GO bit has been set and the ACQT<2:0> bits
are set to ‘010’ which selects a 4 TAD acquisition time
before the conversion starts.
Note:
The GO/DONE bit should not be set in the
same instruction that turns on the ADC.
Refer to Section 19.2.9 “A/D Conversion Procedure”.
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)
TCY - TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11 2 TAD
b4
b1
b0
b6
b7
b2
b9
b8
b3
b5
Conversion starts
Discharge
Holding capacitor is disconnected from analog input (typically 100 ns)
Set GO bit
On the following cycle:
ADRESH:ADRESL is loaded, GO bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)
FIGURE 19-4:
TAD Cycles
TACQT Cycles
1
2
3
Automatic
Acquisition
Time
4
1
3
4
5
b9
b8
b7
b6
6
b5
7
8
9
10
11
b4
b3
b2
b1
b0
Conversion starts
(Holding capacitor is disconnected from analog input)
Set GO bit
(Holding capacitor continues
acquiring input)
DS41303G-page 268
2
2 TAD
Discharge
On the following cycle:
ADRESH:ADRESL is loaded, GO bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
19.2.2
COMPLETION OF A CONVERSION
When the conversion is complete, the ADC module will:
• Clear the GO/DONE bit
• Set the ADIF flag bit
• Update the ADRESH:ADRESL registers with new
conversion result
19.2.3
DISCHARGE
The discharge phase is used to initialize the value of
the capacitor array. The array is discharged after every
sample. This feature helps to optimize the unity-gain
amplifier, as the circuit always needs to charge the
capacitor array, rather than charge/discharge based on
previous measure values.
19.2.4
TERMINATING A CONVERSION
If a conversion must be terminated before completion,
the GO/DONE bit can be cleared by software. The
ADRESH:ADRESL registers will not be updated with
the partially complete Analog-to-Digital conversion
sample. Instead, the ADRESH:ADRESL register pair
will retain the value of the previous conversion.
Note:
19.2.5
A device Reset forces all registers to their
Reset state. Thus, the ADC module is
turned off and any pending conversion is
terminated.
19.2.7
ADC OPERATION DURING SLEEP
The ADC module can operate during Sleep. This
requires the ADC clock source to be set to the FRC
option. When the FRC clock source is selected, the
ADC waits one additional instruction before starting the
conversion. This allows the SLEEP instruction to be
executed, which can reduce system noise during the
conversion. If the ADC interrupt is enabled, the device
will wake-up from Sleep when the conversion
completes. If the ADC interrupt is disabled, the ADC
module is turned off after the conversion completes,
although the ADON bit remains set.
When the ADC clock source is something other than
FRC, a SLEEP instruction causes the present conversion to be aborted and the ADC module is turned off,
although the ADON bit remains set.
19.2.8
SPECIAL EVENT TRIGGER
The CCP2 Special Event Trigger allows periodic ADC
measurements without software intervention. When
this trigger occurs, the GO/DONE bit is set by hardware
and the Timer1 or Timer3 counter resets to zero.
Using the Special Event Trigger does not assure
proper ADC timing. It is the user’s responsibility to
ensure that the ADC timing requirements are met.
See Section 11.3.4 “Special Event Trigger” for more
information.
DELAY BETWEEN CONVERSIONS
After the A/D conversion is completed or aborted, a
2 TAD wait is required before the next acquisition can
be started. After this wait, the currently selected
channel is reconnected to the charge holding capacitor
commencing the next acquisition.
19.2.6
ADC OPERATION IN POWERMANAGED MODES
The selection of the automatic acquisition time and A/D
conversion clock is determined in part by the clock
source and frequency while in a power-managed mode.
If the A/D is expected to operate while the device is in
a power-managed mode, the ACQT<2:0> and
ADCS<2:0> bits in ADCON2 should be updated in
accordance with the clock source to be used in that
mode. After entering the mode, an A/D acquisition or
conversion may be started. Once started, the device
should continue to be clocked by the same clock
source until the conversion has been completed.
If desired, the device may be placed into the
corresponding Idle mode during the conversion. If the
device clock frequency is less than 1 MHz, the A/D FRC
clock source should be selected.
 2010 Microchip Technology Inc.
DS41303G-page 269
PIC18F2XK20/4XK20
19.2.9
A/D CONVERSION PROCEDURE
This is an example procedure for using the ADC to
perform an Analog-to-Digital conversion:
1.
2.
3.
4.
5.
6.
7.
8.
Configure Port:
• Disable pin output driver (See TRIS register)
• Configure pin as analog
Configure the ADC module:
• Select ADC conversion clock
• Configure voltage reference
• Select ADC input channel
• Select result format
• Select acquisition delay
• Turn on ADC module
Configure ADC interrupt (optional):
• Clear ADC interrupt flag
• Enable ADC interrupt
• Enable peripheral interrupt
• Enable global interrupt(1)
Wait the required acquisition time(2).
Start conversion by setting the GO/DONE bit.
Wait for ADC conversion to complete by one of
the following:
• Polling the GO/DONE bit
• Waiting for the ADC interrupt (interrupts
enabled)
Read ADC Result
Clear the ADC interrupt flag (required if interrupt
is enabled).
EXAMPLE 19-1:
A/D CONVERSION
;This code block configures the ADC
;for polling, Vdd and Vss as reference, Frc
clock and AN0 input.
;
;Conversion start & polling for completion
; are included.
;
MOVLW
B’10101111’ ;right justify, Frc,
MOVWF
ADCON2
; & 12 TAD ACQ time
MOVLW
B’00000000’ ;ADC ref = Vdd,Vss
MOVWF
ADCON1
;
BSF
TRISA,0
;Set RA0 to input
BSF
ANSEL,0
;Set RA0 to analog
MOVLW
B’00000001’ ;AN0, ADC on
MOVWF
ADCON0
;
BSF
ADCON0,GO
;Start conversion
ADCPoll:
BTFSC
ADCON0,GO
;Is conversion done?
BRA
ADCPoll
;No, test again
; Result is complete - store 2 MSbits in
; RESULTHI and 8 LSbits in RESULTLO
MOVFF
ADRESH,RESULTHI
MOVFF
ADRESL,RESULTLO
Note 1: The global interrupt can be disabled if the
user is attempting to wake-up from Sleep
and resume in-line code execution.
2: Software delay required if ACQT bits are
set to zero delay. See Section 19.3 “A/D
Acquisition Requirements”.
DS41303G-page 270
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
19.2.10
ADC REGISTER DEFINITIONS
The following registers are used to control the operation of the ADC.
Note:
Analog pin control is performed by the
ANSEL and ANSELH registers. For ANSEL
and ANSELH registers, see Register 10-2
and Register 10-3, respectively.
REGISTER 19-1:
ADCON0: A/D CONTROL REGISTER 0
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
Unimplemented: Read as ‘0’
bit 5-2
CHS<3:0>: Analog Channel Select bits
0000 = AN0
0001 = AN1
0010 = AN2
0011 = AN3
0100 = AN4
0101 = AN5(1)
0110 = AN6(1)
0111 = AN7(1)
1000 = AN8
1001 = AN9
1010 = AN10
1011 = AN11
1100 = AN12
1101 = Reserved
1110 = Reserved
1111 = FVR (1.2 Volt Fixed Voltage Reference)(2)
bit 1
GO/DONE: A/D Conversion Status bit
1 = A/D conversion cycle in progress. Setting this bit starts an A/D conversion cycle.
This bit is automatically cleared by hardware when the A/D conversion has completed.
0 = A/D conversion completed/not in progress
bit 0
ADON: ADC Enable bit
1 = ADC is enabled
0 = ADC is disabled and consumes no operating current
Note 1:
2:
These channels are not implemented on PIC18F2XK20 devices.
Allow greater than 15 s acquisition time when measuring the Fixed Voltage Reference.
 2010 Microchip Technology Inc.
DS41303G-page 271
PIC18F2XK20/4XK20
REGISTER 19-2:
ADCON1: A/D CONTROL REGISTER 1
U-0
U-0
R/W-0
R/W-0
U-0
U-0
U-0
U-0
—
—
VCFG1
VCFG0
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-6
Unimplemented: Read as ‘0’
bit 5
VCFG1: Negative Voltage Reference select bit
1 = Negative voltage reference supplied externally through VREF- pin.
0 = Negative voltage reference supplied internally by VSS.
bit 4
VCFG0: Positive Voltage Reference select bit
1 = Positive voltage reference supplied externally through VREF+ pin.
0 = Positive voltage reference supplied internally by VDD.
bit 3-0
Unimplemented: Read as ‘0’
DS41303G-page 272
x = Bit is unknown
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 19-3:
ADCON2: A/D CONTROL REGISTER 2
R/W-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ADFM
—
ACQT2
ACQT1
ACQT0
ADCS2
ADCS1
ADCS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
x = Bit is unknown
ADFM: A/D Conversion Result Format Select bit
1 = Right justified
0 = Left justified
bit 6
Unimplemented: Read as ‘0’
bit 5-3
ACQT<2:0>: A/D Acquisition time select bits. Acquisition time is the duration that the A/D charge holding capacitor remains connected to A/D channel from the instant the GO/DONE bit is set until conversions begins.
000 = 0(1)
001 = 2 TAD
010 = 4 TAD
011 = 6 TAD
100 = 8 TAD
101 = 12 TAD
110 = 16 TAD
111 = 20 TAD
bit 2-0
ADCS<2:0>: A/D Conversion Clock Select bits
000 = FOSC/2
001 = FOSC/8
010 = FOSC/32
011 = FRC(1) (clock derived from a dedicated internal oscillator = 600 kHz nominal)
100 = FOSC/4
101 = FOSC/16
110 = FOSC/64
111 = FRC(1) (clock derived from a dedicated internal oscillator = 600 kHz nominal)
Note 1:
When the A/D clock source is selected as FRC then the start of conversion is delayed by one instruction
cycle after the GO/DONE bit is set to allow the SLEEP instruction to be executed.
 2010 Microchip Technology Inc.
DS41303G-page 273
PIC18F2XK20/4XK20
REGISTER 19-4:
ADRESH: ADC RESULT REGISTER HIGH (ADRESH) ADFM = 0
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
ADRES9
ADRES8
ADRES7
ADRES6
ADRES5
ADRES4
ADRES3
ADRES2
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
x = Bit is unknown
ADRES<9:2>: ADC Result Register bits
Upper 8 bits of 10-bit conversion result
REGISTER 19-5:
ADRESL: ADC RESULT REGISTER LOW (ADRESL) ADFM = 0
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
ADRES1
ADRES0
—
—
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-6
ADRES<1:0>: ADC Result Register bits
Lower 2 bits of 10-bit conversion result
bit 5-0
Reserved: Do not use.
REGISTER 19-6:
x = Bit is unknown
ADRESH: ADC RESULT REGISTER HIGH (ADRESH) ADFM = 1
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
—
—
—
—
—
—
ADRES9
ADRES8
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-2
Reserved: Do not use.
bit 1-0
ADRES<9:8>: ADC Result Register bits
Upper 2 bits of 10-bit conversion result
REGISTER 19-7:
x = Bit is unknown
ADRESL: ADC RESULT REGISTER LOW (ADRESL) ADFM = 1
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
ADRES7
ADRES6
ADRES5
ADRES4
ADRES3
ADRES2
ADRES1
ADRES0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
x = Bit is unknown
ADRES<7:0>: ADC Result Register bits
Lower 8 bits of 10-bit conversion result
DS41303G-page 274
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
19.3
A/D Acquisition Requirements
For the ADC to meet its specified accuracy, the charge
holding capacitor (CHOLD) must be allowed to fully
charge to the input channel voltage level. The Analog
Input model is shown in Figure 19-5. The source
impedance (RS) and the internal sampling switch (RSS)
impedance directly affect the time required to charge the
capacitor CHOLD. The sampling switch (RSS) impedance
varies over the device voltage (VDD), see Figure 19-5.
The maximum recommended impedance for analog
sources is 10 k. As the source impedance is
decreased, the acquisition time may be decreased.
After the analog input channel is selected (or changed),
EQUATION 19-1:
an A/D acquisition must be done before the conversion
can be started. To calculate the minimum acquisition
time, Equation 19-1 may be used. This equation
assumes that 1/2 LSb error is used (1024 steps for the
ADC). The 1/2 LSb error is the maximum error allowed
for the ADC to meet its specified resolution.
ACQUISITION TIME EXAMPLE
Temperature = 50°C and external impedance of 10k  3.0V V DD
Assumptions:
T ACQ = Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient
= T AMP + T C + T COFF
= 5µs + T C +   Temperature - 25°C   0.05µs/°C  
The value for TC can be approximated with the following equations:
1
V APPLIE D  1 – ------------ = V CHOL D

2047
;[1] VCHOLD charged to within 1/2 lsb
–TC
----------

RC
V APPLIE D  1 – e  = V CHOL D


;[2] VCHOLD charge response to VAPPLIED
– Tc
---------

1
RC
V APPLI ED  1 – e  = V APPL IED  1 – ------------ ;combining [1] and [2]

2047


Solving for TC:
T C = – C HOLD  R IC + R SS + R S  ln(1/2047)
= – 13.5pF  1k  + 700  + 10k   ln(0.0004885)
= 1.20 µs
Therefore:
T ACQ = 5µs + 1.20µs +   50°C- 25°C   0.05  s/ °C  
= 7.45µs
Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out.
2: The charge holding capacitor (CHOLD) is discharged after each conversion.
3: The maximum recommended impedance for analog sources is 10 k. This is required to meet the pin
leakage specification.
 2010 Microchip Technology Inc.
DS41303G-page 275
PIC18F2XK20/4XK20
FIGURE 19-5:
ANALOG INPUT MODEL
VDD
Rs
VA
ANx
RIC  1k
CPIN
5 pF
I LEAKAGE(1)
Sampling
Switch
SS Rss
CHOLD = 13.5 pF
Legend: CPIN
= Input Capacitance
I LEAKAGE = Leakage current at the pin due to
various junctions
= Interconnect Resistance
RIC
SS
= Sampling Switch
CHOLD
= Sample/Hold Capacitance
VDD
Discharge
Switch
3.5V
3.0V
2.5V
2.0V
1.5V
.1
Note 1:
VSS/VREF-
1
10
Rss (k)
100
See Section 26.0 “Electrical Characteristics”.
FIGURE 19-6:
ADC TRANSFER FUNCTION
Full-Scale Range
3FFh
3FEh
ADC Output Code
3FDh
3FCh
1/2 LSB ideal
3FBh
Full-Scale
Transition
004h
003h
002h
001h
000h
Analog Input Voltage
1/2 LSB ideal
VSS/VREF-
DS41303G-page 276
Zero-Scale
Transition
VDD/VREF+
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 19-2:
Name
REGISTERS ASSOCIATED WITH A/D OPERATION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
GIE/GIEH PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
62
PIE1
(1)
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
62
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
62
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
IPR2
ADRESH
A/D Result Register, High Byte
61
ADRESL
A/D Result Register, Low Byte
61
ADCON0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
61
ADCON1
—
—
VCFG1
VCFG0
—
—
—
—
61
ADCON2
ADFM
—
ACQT2
ACQT1
ACQT0
ADCS2
ADCS1
ADCS0
61
ANS7(1)
ANS6(1)
ANS5(1)
ANS4
ANS3
ANS2
ANS1
ANS0
62
—
—
—
ANS12
ANS11
ANS10
ANS9
ANS8
62
PORTA
RA7(2)
RA6(2)
RA5
RA4
RA3
RA2
RA1
RA0
62
TRISA
TRISA7(2)
TRISA6(2)
PORTB
RB7
RB6
RB1
RB0
62
ANSEL
ANSELH
PORTA Data Direction Control Register
RB5
RB4
RB3
RB2
62
TRISB
PORTB Data Direction Control Register
62
LATB
PORTB Data Latch Register (Read and Write to Data Latch)
62
PORTE(4)
—
—
—
—
RE3(3)
RE2
RE1
RE0
62
TRISE(4)
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
62
LATE(4)
—
—
—
—
—
PORTE Data Latch Register
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for A/D conversion.
Note 1: These bits are unimplemented on PIC18F2XK20 devices; always maintain these bits clear.
2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary
oscillator modes. When disabled, these bits read as ‘0’.
3: RE3 port bit is available only as an input pin when the MCLRE Configuration bit is ‘0’.
4: These registers are not implemented on PIC18F2XK20 devices.
 2010 Microchip Technology Inc.
DS41303G-page 277
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 278
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
20.0
COMPARATOR MODULE
Comparators are used to interface analog circuits to a
digital circuit by comparing two analog voltages and
providing a digital indication of their relative magnitudes.
The comparators are very useful mixed signal building
blocks because they provide analog functionality
independent of the program execution. The Analog
Comparator module includes the following features:
•
•
•
•
•
•
•
•
•
Independent comparator control
Programmable input selection
Comparator output is available internally/externally
Programmable output polarity
Interrupt-on-change
Wake-up from Sleep
Programmable Speed/Power optimization
PWM shutdown
Programmable and fixed voltage reference
20.1
Comparator Overview
FIGURE 20-1:
SINGLE COMPARATOR
VIN+
+
VIN-
–
Output
VINVIN+
Output
Note:
The black areas of the output of the
comparator represents the uncertainty
due to input offsets and response time.
A single comparator is shown in Figure 20-1 along with
the relationship between the analog input levels and
the digital output. When the analog voltage at VIN+ is
less than the analog voltage at VIN-, the output of the
comparator is a digital low level. When the analog
voltage at VIN+ is greater than the analog voltage at
VIN-, the output of the comparator is a digital high level.
 2010 Microchip Technology Inc.
DS41303G-page 279
PIC18F2XK20/4XK20
FIGURE 20-2:
COMPARATOR C1 SIMPLIFIED BLOCK DIAGRAM
C1CH<1:0>
2
D
Q1
C12IN0-
0
C12IN1C12IN2-
1
MUX
2
C12IN3-
3
To
Data Bus
Q
EN
RD_CM1CON0
Set C1IF
D
Q3*RD_CM1CON0
Q
EN
CL
Reset
C1ON(1)
C1R
C1IN+
FVR
C1OE
0
MUX
1
0
MUX
C1VREF
1
CVREF
C1RSEL
Note 1:
2:
3:
4:
FIGURE 20-3:
To PWM Logic
C1VIN- C1VIN+ C1
+
C1OUT
C1OUT pin(2)
C1SP
C1POL
When C1ON = 0, the C1 comparator will produce a ‘0’ output to the XOR Gate.
Output shown for reference only. See I/O port pin block diagram for more detail.
Q1 and Q3 are phases of the four-phase system clock (FOSC).
Q1 is held high during Sleep mode.
COMPARATOR C2 SIMPLIFIED BLOCK DIAGRAM
D
Q1
To
Data Bus
Q
EN
RD_CM2CON0
C2CH<1:0>
Set C2IF
2
C12IN0-
0
C12IN1C12IN2-
1
MUX
2
C12IN3-
3
C2R
C2IN+
FVR
CVREF
C2RSEL
C2ON(1)
Q3*RD_CM2CON0
Q
EN
CL
NRESET
To PWM Logic
C2OE
C2VINC2VIN+
C2
C2OUT
C2OUT pin(2)
C2SP
C2POL
0
MUX
1
0
MUX
C2VREF
1
Note 1:
2:
3:
4:
DS41303G-page 280
D
When C2ON = 0, the C2 comparator will produce a ‘0’ output to the XOR Gate.
Output shown for reference only. See I/O port pin block diagram for more detail.
Q1 and Q3 are phases of the four-phase system clock (FOSC).
Q1 is held high during Sleep mode.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
20.2
Comparator Control
Each comparator has a separate control and Configuration register: CM1CON0 for Comparator C1 and
CM2CON0 for Comparator C2. In addition, Comparator C2 has a second control register, CM2CON1, for
controlling the interaction with Timer1 and simultaneous reading of both comparator outputs.
The CM1CON0 and CM2CON0 registers (see Registers 20-1 and 20-2, respectively) contain the control
and Status bits for the following:
•
•
•
•
•
•
Enable
Input selection
Reference selection
Output selection
Output polarity
Speed selection
20.2.1
COMPARATOR ENABLE
Note 1: The CxOE bit overrides the PORT data
latch. Setting the CxON has no impact on
the port override.
2: The internal output of the comparator is
latched with each instruction cycle.
Unless otherwise specified, external
outputs are not latched.
20.2.5
COMPARATOR OUTPUT POLARITY
Inverting the output of the comparator is functionally
equivalent to swapping the comparator inputs. The
polarity of the comparator output can be inverted by
setting the CxPOL bit of the CMxCON0 register.
Clearing the CxPOL bit results in a non-inverted output.
Table 20-1 shows the output state versus input
conditions, including polarity control.
TABLE 20-1:
COMPARATOR OUTPUT
STATE VS. INPUT
CONDITIONS
Setting the CxON bit of the CMxCON0 register enables
the comparator for operation. Clearing the CxON bit
disables the comparator resulting in minimum current
consumption.
Input Condition
CxPOL
CxOUT
CxVIN- > CxVIN+
0
0
20.2.2
CxVIN- < CxVIN+
0
1
CxVIN- > CxVIN+
1
1
CxVIN- < CxVIN+
1
0
COMPARATOR INPUT SELECTION
The CxCH<1:0> bits of the CMxCON0 register direct
one of four analog input pins to the comparator
inverting input.
Note:
20.2.3
To use CxIN+ and C12INx- pins as analog
inputs, the appropriate bits must be set in
the ANSEL register and the corresponding
TRIS bits must also be set to disable the
output drivers.
COMPARATOR REFERENCE
SELECTION
Setting the CxR bit of the CMxCON0 register directs an
internal voltage reference or an analog input pin to the
non-inverting input of the comparator. See
Section 21.0 “VOLTAGE REFERENCES” for more
information on the Internal Voltage Reference module.
20.2.4
COMPARATOR OUTPUT
SELECTION
The output of the comparator can be monitored by
reading either the CxOUT bit of the CMxCON0 register
or the MCxOUT bit of the CM2CON1 register. In order
to make the output available for an external connection,
the following conditions must be true:
20.2.6
COMPARATOR SPEED SELECTION
The trade-off between speed or power can be optimized during program execution with the CxSP control
bit. The default state for this bit is ‘1’ which selects the
normal speed mode. Device power consumption can
be optimized at the cost of slower comparator propagation delay by clearing the CxSP bit to ‘0’.
20.3
Comparator Response Time
The comparator output is indeterminate for a period of
time after the change of an input source or the selection
of a new reference voltage. This period is referred to as
the response time. The response time of the
comparator differs from the settling time of the voltage
reference. Therefore, both of these times must be
considered when determining the total response time
to a comparator input change. See the Comparator and
Voltage Reference Specifications in Section 26.0
“Electrical Characteristics” for more details.
• CxOE bit of the CMxCON0 register must be set
• Corresponding TRIS bit must be cleared
• CxON bit of the CMxCON0 register must be set
 2010 Microchip Technology Inc.
DS41303G-page 281
PIC18F2XK20/4XK20
20.4
Comparator Interrupt Operation
The comparator interrupt flag can be set whenever
there is a change in the output value of the comparator.
Changes are recognized by means of a mismatch
circuit which consists of two latches and an exclusiveor gate (see Figure 20-2 and Figure 20-3). One latch is
updated with the comparator output level when the
CMxCON0 register is read. This latch retains the value
until the next read of the CMxCON0 register or the
occurrence of a Reset. The other latch of the mismatch
circuit is updated on every Q1 system clock. A
mismatch condition will occur when a comparator
output change is clocked through the second latch on
the Q1 clock cycle. At this point the two mismatch
latches have opposite output levels which is detected
by the exclusive-or gate and fed to the interrupt
circuitry. The mismatch condition persists until either
the CMxCON0 register is read or the comparator
output returns to the previous state.
Note 1: A write operation to the CMxCON0
register will also clear the mismatch
condition because all writes include a read
operation at the beginning of the write
cycle.
20.4.1
PRESETTING THE MISMATCH
LATCHES
The comparator mismatch latches can be preset to the
desired state before the comparators are enabled.
When the comparator is off the CxPOL bit controls the
CxOUT level. Set the CxPOL bit to the desired CxOUT
non-interrupt level while the CxON bit is cleared. Then,
configure the desired CxPOL level in the same instruction that the CxON bit is set. Since all register writes are
performed as a Read-Modify-Write, the mismatch
latches will be cleared during the instruction Read
phase and the actual configuration of the CxON and
CxPOL bits will be occur in the final Write phase.
FIGURE 20-4:
COMPARATOR
INTERRUPT TIMING W/O
CMxCON0 READ
Q1
Q3
CxIN+
TRT
CxOUT
Set CxIF (edge)
CxIF
reset by software
2: Comparator interrupts will operate correctly
regardless of the state of CxOE.
The comparator interrupt is set by the mismatch edge
and not the mismatch level. This means that the interrupt flag can be reset without the additional step of
reading or writing the CMxCON0 register to clear the
mismatch registers. When the mismatch registers are
cleared, an interrupt will occur upon the comparator’s
return to the previous state, otherwise no interrupt will
be generated.
FIGURE 20-5:
Software will need to maintain information about the
status of the comparator output, as read from the
CMxCON0 register, or CM2CON1 register, to determine
the actual change that has occurred. See Figures 20-4
and 20-5.
Set CxIF (edge)
The CxIF bit of the PIR2 register is the comparator
interrupt flag. This bit must be reset by software by
clearing it to ‘0’. Since it is also possible to write a ‘1’ to
this register, an interrupt can be generated.
In mid-range Compatibility mode the CxIE bit of the
PIE2 register and the PEIE and GIE bits of the INTCON
register must all be set to enable comparator interrupts.
If any of these bits are cleared, the interrupt is not
enabled, although the CxIF bit of the PIR2 register will
still be set if an interrupt condition occurs.
DS41303G-page 282
COMPARATOR
INTERRUPT TIMING WITH
CMxCON0 READ
Q1
Q3
CxIN+
TRT
CxOUT
CxIF
cleared by CMxCON0 read
reset by software
Note 1: If a change in the CMxCON0 register
(CxOUT) should occur when a read operation is being executed (start of the Q2
cycle), then the CxIF interrupt flag of the
PIR2 register may not get set.
2: When either comparator is first enabled,
bias circuitry in the Comparator module
may cause an invalid output from the
comparator until the bias circuitry is stable.
Allow about 1 s for bias settling then clear
the mismatch condition and interrupt flags
before enabling comparator interrupts.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
20.5
Operation During Sleep
The comparator, if enabled before entering Sleep mode,
remains active during Sleep. The additional current
consumed by the comparator is shown separately in the
Section 26.0 “Electrical Characteristics”. If the
comparator is not used to wake the device, power
consumption can be minimized while in Sleep mode by
turning off the comparator. Each comparator is turned off
by clearing the CxON bit of the CMxCON0 register.
A change to the comparator output can wake-up the
device from Sleep. To enable the comparator to wake
the device from Sleep, the CxIE bit of the PIE2 register
and the PEIE bit of the INTCON register must be set.
The instruction following the SLEEP instruction always
executes following a wake from Sleep. If the GIE bit of
the INTCON register is also set, the device will then
execute the Interrupt Service Routine.
20.6
Effects of a Reset
A device Reset forces the CMxCON0 and CM2CON1
registers to their Reset states. This forces both
comparators and the voltage references to their Off
states.
 2010 Microchip Technology Inc.
DS41303G-page 283
PIC18F2XK20/4XK20
REGISTER 20-1:
CM1CON0: COMPARATOR 1 CONTROL REGISTER 0
R/W-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
C1ON
C1OUT
C1OE
C1POL
C1SP
C1R
C1CH1
C1CH0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
C1ON: Comparator C1 Enable bit
1 = Comparator C1 is enabled
0 = Comparator C1 is disabled
bit 6
C1OUT: Comparator C1 Output bit
If C1POL = 1 (inverted polarity):
C1OUT = 0 when C1VIN+ > C1VINC1OUT = 1 when C1VIN+ < C1VINIf C1POL = 0 (non-inverted polarity):
C1OUT = 1 when C1VIN+ > C1VINC1OUT = 0 when C1VIN+ < C1VIN-
bit 5
C1OE: Comparator C1 Output Enable bit
1 = C1OUT is present on the C1OUT pin(1)
0 = C1OUT is internal only
bit 4
C1POL: Comparator C1 Output Polarity Select bit
1 = C1OUT logic is inverted
0 = C1OUT logic is not inverted
bit 3
C1SP: Comparator C1 Speed/Power Select bit
1 = C1 operates in normal power, higher speed mode
0 = C1 operates in low-power, low-speed mode
bit 2
C1R: Comparator C1 Reference Select bit (non-inverting input)
1 = C1VIN+ connects to C1VREF output
0 = C1VIN+ connects to C1IN+ pin
bit 1-0
C1CH<1:0>: Comparator C1 Channel Select bit
00 = C12IN0- pin of C1 connects to C1VIN01 = C12IN1- pin of C1 connects to C1VIN10 = C12IN2- pin of C1 connects to C1VIN11 = C12IN3- pin of C1 connects to C1VIN-
Note 1:
x = Bit is unknown
Comparator output requires the following three conditions: C1OE = 1, C1ON = 1 and corresponding port
TRIS bit = 0.
DS41303G-page 284
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 20-2:
CM2CON0: COMPARATOR 2 CONTROL REGISTER 0
R/W-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
C2ON
C2OUT
C2OE
C2POL
C2SP
C2R
C2CH1
C2CH0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
C2ON: Comparator C2 Enable bit
1 = Comparator C2 is enabled
0 = Comparator C2 is disabled
bit 6
C2OUT: Comparator C2 Output bit
If C2POL = 1 (inverted polarity):
C2OUT = 0 when C2VIN+ > C2VINC2OUT = 1 when C2VIN+ < C2VINIf C2POL = 0 (non-inverted polarity):
C2OUT = 1 when C2VIN+ > C2VINC2OUT = 0 when C2VIN+ < C2VIN-
bit 5
C2OE: Comparator C2 Output Enable bit
1 = C2OUT is present on C2OUT pin(1)
0 = C2OUT is internal only
bit 4
C2POL: Comparator C2 Output Polarity Select bit
1 = C2OUT logic is inverted
0 = C2OUT logic is not inverted
bit 3
C2SP: Comparator C2 Speed/Power Select bit
1 = C2 operates in normal power, higher speed mode
0 = C2 operates in low-power, low-speed mode
bit 2
C2R: Comparator C2 Reference Select bits (non-inverting input)
1 = C2VIN+ connects to C2VREF
0 = C2VIN+ connects to C2IN+ pin
bit 1-0
C2CH<1:0>: Comparator C2 Channel Select bits
00 = C12IN0- pin of C2 connects to C2VIN01 = C12IN1- pin of C2 connects to C2VIN10 = C12IN2- pin of C2 connects to C2VIN11 = C12IN3- pin of C2 connects to C2VIN-
Note 1:
x = Bit is unknown
Comparator output requires the following three conditions: C2OE = 1, C2ON = 1 and corresponding port
TRIS bit = 0.
 2010 Microchip Technology Inc.
DS41303G-page 285
PIC18F2XK20/4XK20
20.7
Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 20-6. Since the analog input pins share their
connection with a digital input, they have reverse
biased ESD protection diodes to VDD and VSS. The
analog input, therefore, must be between VSS and VDD.
If the input voltage deviates from this range by more
than 0.6V in either direction, one of the diodes is
forward biased and a latch-up may occur.
Note 1: When reading a PORT register, all pins
configured as analog inputs will read as a
‘0’. Pins configured as digital inputs will
convert as an analog input, according to
the input specification.
2: Analog levels on any pin defined as a
digital input, may cause the input buffer to
consume more current than is specified.
A maximum source impedance of 10 k is recommended
for the analog sources. Also, any external component
connected to an analog input pin, such as a capacitor or
a Zener diode, should have very little leakage current to
minimize inaccuracies introduced.
FIGURE 20-6:
ANALOG INPUT MODEL
VDD
RIC
Rs < 10K
AIN
VA
CPIN
5 pF
ILEAKAGE(1)
Vss
Legend: CPIN
= Input Capacitance
ILEAKAGE = Leakage Current at the pin due to various junctions
RIC
= Interconnect Resistance
= Source Impedance
RS
= Analog Voltage
VA
Note 1: See Section 26.0 “Electrical Characteristics”.
DS41303G-page 286
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
20.8
Additional Comparator Features
20.8.2
There are two additional comparator features:
• Simultaneous read of comparator outputs
• Internal reference selection
20.8.1
SIMULTANEOUS COMPARATOR
OUTPUT READ
The MC1OUT and MC2OUT bits of the CM2CON1
register are mirror copies of both comparator outputs.
The ability to read both outputs simultaneously from a
single register eliminates the timing skew of reading
separate registers.
INTERNAL REFERENCE
SELECTION
There are two internal voltage references available to
the non-inverting input of each comparator. One of
these is the 1.2V Fixed Voltage Reference (FVR) and
the other is the variable Comparator Voltage Reference
(CVREF). The CxRSEL bit of the CM2CON register
determines which of these references is routed to the
Comparator Voltage reference output (CXVREF). Further routing to the comparator is accomplished by the
CxR bit of the CMxCON0 register. See Section 21.1
“Comparator Voltage Reference” and Figure 20-2
and Figure 20-3 for more detail.
Note 1: Obtaining the status of C1OUT or C2OUT
by reading CM2CON1 does not affect the
comparator interrupt mismatch registers.
REGISTER 20-3:
CM2CON1: COMPARATOR 2 CONTROL REGISTER 1
R-0
R-0
R/W-0
R/W-0
U-0
U-0
U-0
U-0
MC1OUT
MC2OUT
C1RSEL
C2RSEL
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
MC1OUT: Mirror Copy of C1OUT bit
bit 6
MC2OUT: Mirror Copy of C2OUT bit
bit 5
C1RSEL: Comparator C1 Reference Select bit
1 = CVREF routed to C1VREF input
0 = FVR (1.2 Volt fixed voltage reference) routed to C1VREF input
bit 4
C2RSEL: Comparator C2 Reference Select bit
1 = CVREF routed to C2VREF input
0 = FVR (1.2 Volt fixed voltage reference) routed to C2VREF input
bit 3-0
Unimplemented: Read as ‘0’
 2010 Microchip Technology Inc.
x = Bit is unknown
DS41303G-page 287
PIC18F2XK20/4XK20
TABLE 20-2:
REGISTERS ASSOCIATED WITH COMPARATOR MODULE
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
CM1CON0
C1ON
C1OUT
C1OE
C1POL
C1SP
C1R
C1CH1
C1CH0
62
CM2CON0
C2ON
C2OUT
C2OE
C2POL
C2SP
C2R
C2CH1
C2CH0
62
CM2CON1
MC1OUT
MC2OUT
C1RSEL
C2RSEL
—
—
—
—
63
CVRCON
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
61
FVREN
FVRST
CVRCON2
INTCON
GIE/GIEH PEIE/GIEL
—
—
—
—
—
—
61
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
RA7(1)
RA6(1)
RA5
RA4
RA3
RA2
RA1
RA0
62
LATA
LATA7(1)
LATA6(1)
TRISA
TRISA7(1)
TRISA6(1) PORTA Data Direction Control Register
PORTA
PORTA Data Latch Register (Read and Write to Data Latch)
62
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are unused by the comparator module.
Note 1: PORTA<7:6> and their direction and latch bits are individually configured as port pins based on various
primary oscillator modes. When disabled, these bits read as ‘0’.
DS41303G-page 288
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
21.0
VOLTAGE REFERENCES
There are two independent voltage references
available:
• Programmable Comparator Voltage Reference
• 1.2V Fixed Voltage Reference
21.1
Comparator Voltage Reference
The Comparator Voltage Reference module provides
an internally generated voltage reference for the comparators. The following features are available:
•
•
•
•
•
Independent from Comparator operation
Two 16-level voltage ranges
Output clamped to VSS
Ratiometric with VDD
1.2 Fixed Reference Voltage (FVR)
The CVRCON register (Register 21-1) controls the
Voltage Reference module shown in Figure 21-1.
21.1.1
INDEPENDENT OPERATION
The comparator voltage reference is independent of
the comparator configuration. Setting the CVREN bit of
the CVRCON register will enable the voltage reference
by allowing current to flow in the CVREF voltage divider.
When both the CVREN bit is cleared, current flow in the
CVREF voltage divider is disabled minimizing the power
drain of the voltage reference peripheral.
21.1.2
OUTPUT VOLTAGE SELECTION
The CVREF voltage reference has 2 ranges with 16
voltage levels in each range. Range selection is
controlled by the CVRR bit of the CVRCON register.
The 16 levels are set with the CVR<3:0> bits of the
CVRCON register.
21.1.3
OUTPUT CLAMPED TO VSS
The CVREF output voltage can be set to Vss with no
power consumption by configuring CVRCON as
follows:
• CVREN = 0
• CVRR = 1
• CVR<3:0> = 0000
This allows the comparator to detect a zero-crossing
while not consuming additional CVREF module current.
21.1.4
OUTPUT RATIOMETRIC TO VDD
The comparator voltage reference is VDD derived and
therefore, the CVREF output changes with fluctuations in
VDD. The tested absolute accuracy of the Comparator
Voltage Reference can be found in Section 26.0
“Electrical Characteristics”.
21.1.5
VOLTAGE REFERENCE OUTPUT
The CVREF voltage reference can be output to the
device CVREF pin by setting the CVROE bit of the CVRCON register to ‘1’. Selecting the reference voltage for
output on the CVREF pin automatically overrides the
digital output buffer and digital input threshold detector
functions of that pin. Reading the CVREF pin when it
has been configured for reference voltage output will
always return a ‘0’.
Due to the limited current drive capability, a buffer must
be used on the voltage reference output for external
connections to CVREF. Figure 21-2 shows an example
buffering technique.
21.1.6
OPERATION DURING SLEEP
The CVREF output voltage is determined by the
following equations:
When the device wakes up from Sleep through an
interrupt or a Watchdog Timer time-out, the contents of
the CVRCON register are not affected. To minimize
current consumption in Sleep mode, the voltage
reference should be disabled.
EQUATION 21-1:
21.1.7
CVREF OUTPUT VOLTAGE
CV RR = 1 (low range):
CVREF = (CVRSRC/24) X CVR<3:0> + VREFCV RR = 0 (high range):
CVREF = (CVRSRC/32) X (8 + CVR<3:0>) + VREFCV RSRC = V DD or [(VREF+) - (VREF-)]
EFFECTS OF A RESET
A device Reset affects the following:
•
•
•
•
•
Comparator voltage reference is disabled
Fixed voltage reference is disabled
CVREF is removed from the CVREF pin
The high-voltage range is selected
The CVR<3:0> range select bits are cleared
Note: VREF- is 0 when CVRSS = 0
The full range of VSS to VDD cannot be realized due to
the construction of the module. See Figure 21-1.
 2010 Microchip Technology Inc.
DS41303G-page 289
PIC18F2XK20/4XK20
21.2
21.2.1
FVR Reference Module
When the Fixed Voltage Reference module is enabled, it
will require some time for the reference and its amplifier
circuits to stabilize. The user program must include a
small delay routine to allow the module to settle. The
FVRST stable bit of the CVRCON2 register also indicates
that the FVR reference has been operating long enough
to be stable. See Section 26.0 “Electrical
Characteristics” for the minimum delay requirement.
The FVR reference is a stable fixed voltage reference,
independent of VDD, with a nominal output voltage of
1.2V. This reference can be enabled by setting the
FVREN bit of the CVRCON2 register to ‘1’. The FVR
defaults to on when any one or more of the HFINTOSC,
HLVD, or BOR functions are enabled. The FVR voltage
reference can be routed to the comparators or an ADC
input channel.
FIGURE 21-1:
FVR STABILIZATION PERIOD
VOLTAGE REFERENCE BLOCK DIAGRAM
CVRSS = 1
VREF+
VDD
8R
CVRSS = 0
CVR<3:0>
R
CVREN
R
16-to-1 MUX
R
R
16 Steps
CVREF
R
R
R
CVRR
8R
CVRSS = 1
VREF-
CVRSS = 0
1.2 Volt Fixed
Reference
FVREN
From HVLD and
BOR circuits
DS41303G-page 290
EN
FVR
FVRST
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 21-2:
VOLTAGE REFERENCE OUTPUT BUFFER EXAMPLE
PIC18F2XK20/4XK20
CVREF
Module
R(1)
Voltage
Reference
Output
Impedance
Note 1:
+
–
CVREF
Buffered CVREF Output
R is dependent upon the voltage reference Configuration bits, CVR<3:0> and CVRR.
REGISTER 21-1:
R/W-0
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
R/W-0
(1)
CVREN
CVROE
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
CVREN: Comparator Voltage Reference Enable bit
1 = CVREF circuit powered on
0 = CVREF circuit powered down
bit 6
CVROE: Comparator VREF Output Enable bit(1)
1 = CVREF voltage level is also output on the CVREF pin
0 = CVREF voltage is disconnected from the CVREF pin
bit 5
CVRR: Comparator VREF Range Selection bit
1 = 0 to 0.667 CVRSRC, with CVRSRC/24 step size (low range)
0 = 0.25 CVRSRC to 0.75 CVRSRC, with CVRSRC/32 step size (high range)
bit 4
CVRSS: Comparator VREF Source Selection bit
1 = Comparator reference source, CVRSRC = (VREF+) – (VREF-)
0 = Comparator reference source, CVRSRC = VDD – VSS
bit 3-0
CVR<3:0>: Comparator VREF Value Selection bits (0  (CVR<3:0>)  15)
When CVRR = 1:
CVREF = ((CVR<3:0>)/24)  (CVRSRC) + VREFWhen CVRR = 0:
CVREF = (CVRSRC/4) + ((CVR<3:0>)/32)  (CVRSRC) + VREF-
Note 1:
CVROE overrides the TRISA<2> bit setting.
 2010 Microchip Technology Inc.
DS41303G-page 291
PIC18F2XK20/4XK20
REGISTER 21-2:
CVRCON2: COMPARATOR VOLTAGE REFERENCE CONTROL 2 REGISTER
R/W-0
R-0
U-0
U-0
U-0
U-0
U-0
U-0
FVREN
FVRST
—
—
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
FVREN: Fixed Voltage Reference Enable bit
1 = FVR circuit powered on
0 = FVR circuit not enabled by FVREN. Other peripherals may enable FVR.
bit 6
FVRST: Fixed Voltage Stable Status bit
1 = FVR is stable and can be used.
0 = FVR is not stable and should not be used.
bit 5-0
Unimplemented: Read as ‘0’.
TABLE 21-1:
REGISTERS ASSOCIATED WITH COMPARATOR VOLTAGE REFERENCE
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
CVRCON
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
62
CVRCON2
FVREN
FVRST
—
—
—
—
—
—
61
CM1CON0
C1ON
C1OUT
C1OE
C1POL
C1SP
C1R
C1CH1
C1CH0
62
CM2CON0
C2ON
C2OUT
C2OE
C2POL
C2SP
C2R
C2CH1
C2CH0
62
—
—
—
—
63
Name
CM2CON1
MC1OUT MC2OUT C1RSEL C2RSEL
TRISA
TRISA7(1) TRISA6(1) PORTA Data Direction Control Register
62
Legend: Shaded cells are not used with the comparator voltage reference.
Note 1: PORTA pins are enabled based on oscillator configuration.
DS41303G-page 292
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
22.0
HIGH/LOW-VOLTAGE
DETECT (HLVD)
The block diagram for the HLVD module is shown in
Figure 22-1.
PIC18F2XK20/4XK20 devices have a High/Low-Voltage
Detect module (HLVD). This is a programmable circuit
that allows the user to specify both a device voltage trip
point and the direction of change from that point. If the
device experiences an excursion past the trip point in
that direction, an interrupt flag is set. If the interrupt is
enabled, the program execution will branch to the interrupt vector address and the software can then respond
to the interrupt.
The High/Low-Voltage Detect Control register
(Register 22-1) completely controls the operation of the
HLVD module. This allows the circuitry to be “turned
off” by the user under software control, which
minimizes the current consumption for the device.
REGISTER 22-1:
R/W-0
The VDIRMAG bit determines the overall operation of
the module. When VDIRMAG is cleared, the module
monitors for drops in VDD below a predetermined set
point. When the bit is set, the module monitors for rises
in VDD above the set point.
HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER
U-0
VDIRMAG
The module is enabled by setting the HLVDEN bit.
Each time that the HLVD module is enabled, the circuitry requires some time to stabilize. The IRVST bit is
a read-only bit and is used to indicate when the circuit
is stable. The module can only generate an interrupt
after the circuit is stable and IRVST is set.
—
R-0
IRVST
R/W-0
R/W-0
R/W-1
R/W-0
R/W-1
HLVDEN
HLVDL3(1)
HLVDL2(1)
HLVDL1(1)
HLVDL0(1)
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented
C = Clearable only bit
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
VDIRMAG: Voltage Direction Magnitude Select bit
1 = Event occurs when voltage equals or exceeds trip point (HLVDL<3:0>)
0 = Event occurs when voltage equals or falls below trip point (HLVDL<3:0>)
bit 6
Unimplemented: Read as ‘0’
bit 5
IRVST: Internal Reference Voltage Stable Flag bit
1 = Indicates that the voltage detect logic will generate the interrupt flag at the specified voltage range
0 = Indicates that the voltage detect logic will not generate the interrupt flag at the specified voltage
range and the HLVD interrupt should not be enabled
bit 4
HLVDEN: High/Low-Voltage Detect Power Enable bit
1 = HLVD enabled
0 = HLVD disabled
bit 3-0
HLVDL<3:0>: Voltage Detection Limit bits(1)
1111 = External analog input is used (input comes from the HLVDIN pin)
1110 = Maximum setting
.
.
.
0000 = Minimum setting
Note 1:
See Table 26-4 for specifications.
 2010 Microchip Technology Inc.
DS41303G-page 293
PIC18F2XK20/4XK20
22.1
Operation
When the HLVD module is enabled, a comparator uses
an internally generated reference voltage as the set
point. The set point is compared with the trip point,
where each node in the resistor divider represents a
trip point voltage. The “trip point” voltage is the voltage
level at which the device detects a high or low-voltage
event, depending on the configuration of the module.
When the supply voltage is equal to the trip point, the
voltage tapped off of the resistor array is equal to the
internal reference voltage generated by the voltage
reference module. The comparator then generates an
interrupt signal by setting the HLVDIF bit.
FIGURE 22-1:
The trip point voltage is software programmable to any
one of 16 values. The trip point is selected by
programming the HLVDL<3:0> bits of the HLVDCON
register.
The HLVD module has an additional feature that allows
the user to supply the trip voltage to the module from
an external source. This mode is enabled when bits
HLVDL<3:0> are set to ‘1111’. In this state, the
comparator input is multiplexed from the external input
pin, HLVDIN. This gives users flexibility because it
allows them to configure the High/Low-Voltage Detect
interrupt to occur at any voltage in the valid operating
range.
HLVD MODULE BLOCK DIAGRAM (WITH EXTERNAL INPUT)
Externally Generated
Trip Point
VDD
VDD
HLVDCON
Register
HLVDEN
HLVDIN
16-to-1 MUX
HLVDIN
HLVDL<3:0>
VDIRMAG
Set
HLVDIF
HLVDEN
BOREN
DS41303G-page 294
Internal Voltage
Reference
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
22.2
HLVD Setup
The following steps are needed to set up the HLVD
module:
1.
2.
3.
4.
5.
Write the value to the HLVDL<3:0> bits that
selects the desired HLVD trip point.
Set the VDIRMAG bit to detect high voltage
(VDIRMAG = 1) or low voltage (VDIRMAG = 0).
Enable the HLVD module by setting the
HLVDEN bit.
Clear the HLVD interrupt flag bit of the PIR2
register, which may have been set from a
previous interrupt.
Enable the HLVD interrupt if interrupts are
desired by setting the HLVDIE bit of the PIE2
register, and the GIE and PEIE bits of the INTCON register. An interrupt will not be generated
until the IRVST bit is set.
22.3
22.4
HLVD Start-up Time
The internal reference voltage of the HLVD module,
specified in electrical specification parameter D420,
may be used by other internal circuitry, such as the
Programmable Brown-out Reset. If the HLVD or other
circuits using the voltage reference are disabled to
lower the device’s current consumption, the reference
voltage circuit will require time to become stable before
a low or high-voltage condition can be reliably
detected. This start-up time, TIRVST, is an interval that
is independent of device clock speed. It is specified in
electrical specification parameter 36.
Current Consumption
When the module is enabled, the HLVD comparator
and voltage divider are enabled and will consume static
current. The total current consumption, when enabled,
is specified in electrical specification parameter D024B.
FIGURE 22-2:
Depending on the application, the HLVD module does
not need to be operating constantly. To decrease the
current requirements, the HLVD circuitry may only
need to be enabled for short periods where the voltage
is checked. After doing the check, the HLVD module
may be disabled.
The HLVD interrupt flag is not enabled until TIRVST has
expired and a stable reference voltage is reached. For
this reason, brief excursions beyond the set point may
not be detected during this interval. Refer to Figure 22-2
or Figure 22-3.
LOW-VOLTAGE DETECT OPERATION (VDIRMAG = 0)
CASE 1:
HLVDIF may not be set
VDD
VHLVD
HLVDIF
Enable HLVD
TIVRST
IRVST
Internal Reference is stable
HLVDIF cleared by software
CASE 2:
VDD
VHLVD
HLVDIF
Enable HLVD
TIVRST
IRVST
Internal Reference is stable
HLVDIF cleared by software
HLVDIF cleared by software,
HLVDIF remains set since HLVD condition still exists
 2010 Microchip Technology Inc.
DS41303G-page 295
PIC18F2XK20/4XK20
FIGURE 22-3:
HIGH-VOLTAGE DETECT OPERATION (VDIRMAG = 1)
CASE 1:
HLVDIF may not be set
VHLVD
VDD
HLVDIF
Enable HLVD
TIVRST
IRVST
HLVDIF cleared by software
Internal Reference is stable
CASE 2:
VHLVD
VDD
HLVDIF
Enable HLVD
TIVRST
IRVST
Internal Reference is stable
HLVDIF cleared by software
HLVDIF cleared by software,
HLVDIF remains set since HLVD condition still exists
DS41303G-page 296
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 22-4:
Applications
In many applications, the ability to detect a drop below,
or rise above, a particular threshold is desirable. For
example, the HLVD module could be periodically
enabled to detect Universal Serial Bus (USB) attach or
detach. This assumes the device is powered by a lower
voltage source than the USB when detached. An attach
would indicate a high-voltage detect from, for example,
3.3V to 5V (the voltage on USB) and vice versa for a
detach. This feature could save a design a few extra
components and an attach signal (input pin).
VA
VB
For general battery applications, Figure 22-4 shows a
possible voltage curve. Over time, the device voltage
decreases. When the device voltage reaches voltage
VA, the HLVD logic generates an interrupt at time TA.
The interrupt could cause the execution of an ISR,
which would allow the application to perform
“housekeeping tasks” and perform a controlled
shutdown before the device voltage exits the valid
operating range at TB. The HLVD, thus, would give the
application a time window, represented by the
difference between TA and TB, to safely exit.
TABLE 22-1:
TYPICAL LOW-VOLTAGE
DETECT APPLICATION
Voltage
22.5
Time
TA
TB
Legend: VA = HLVD trip point
VB = Minimum valid device
operating voltage
REGISTERS ASSOCIATED WITH HIGH/LOW-VOLTAGE DETECT MODULE
Name
Bit 7
Bit 6
HLVDCON
VDIRMAG
—
INTCON
GIE/GIEH PEIE/GIEL
Reset
Values
on Page
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
IRVST
HLVDEN
HLVDL3
HLVDL2
HLVDL1
HLVDL0
60
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
59
PIR2
OSCFIF
C1IF
C2IF
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
62
PIE2
OSCFIE
C1IE
C2IE
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
62
IPR2
OSCFIP
C1IP
C2IP
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
62
Legend: — = unimplemented, read as ‘0’. Shaded cells are unused by the HLVD module.
 2010 Microchip Technology Inc.
DS41303G-page 297
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 298
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
23.0
SPECIAL FEATURES OF
THE CPU
PIC18F2XK20/4XK20 devices include several features
intended to maximize reliability and minimize cost through
elimination of external components. These are:
• Oscillator Selection
• Resets:
- Power-on Reset (POR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Brown-out Reset (BOR)
• Interrupts
• Watchdog Timer (WDT)
• Code Protection
• ID Locations
• In-Circuit Serial Programming™
The oscillator can be configured for the application
depending on frequency, power, accuracy and cost. All
of the options are discussed in detail in Section 2.0
“Oscillator Module (With Fail-Safe Clock Monitor)”.
A complete discussion of device Resets and interrupts
is available in previous sections of this data sheet.
In addition to their Power-up and Oscillator Start-up
Timers provided for Resets, PIC18F2XK20/4XK20
devices have a Watchdog Timer, which is either
permanently enabled via the Configuration bits or
software controlled (if configured as disabled).
The inclusion of an internal RC oscillator also provides
the additional benefits of a Fail-Safe Clock Monitor
(FSCM) and Two-Speed Start-up. FSCM provides for
background monitoring of the peripheral clock and
automatic switchover in the event of its failure. TwoSpeed Start-up enables code to be executed almost
immediately on start-up, while the primary clock source
completes its start-up delays.
All of these features are enabled and configured by
setting the appropriate Configuration register bits.
 2010 Microchip Technology Inc.
DS41303G-page 299
PIC18F2XK20/4XK20
23.1
Configuration Bits
The Configuration bits can be programmed (read as
‘0’) or left unprogrammed (read as ‘1’) to select various
device configurations. These bits are mapped starting
at program memory location 300000h.
The user will note that address 300000h is beyond the
user program memory space. In fact, it belongs to the
configuration memory space (300000h-3FFFFFh), which
can only be accessed using table reads and table writes.
Programming the Configuration registers is done in a
manner similar to programming the Flash memory. The
WR bit in the EECON1 register starts a self-timed write
to the Configuration register. In normal operation mode,
a TBLWT instruction with the TBLPTR pointing to the
Configuration register sets up the address and the data
for the Configuration register write. Setting the WR bit
starts a long write to the Configuration register. The
Configuration registers are written a byte at a time. To
write or erase a configuration cell, a TBLWT instruction
can write a ‘1’ or a ‘0’ into the cell. For additional details
on Flash programming, refer to Section 6.5 “Writing
to Flash Program Memory”.
TABLE 23-1:
CONFIGURATION BITS AND DEVICE IDs
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
300001h
CONFIG1H
IESO
FCMEN
—
—
FOSC3
FOSC2
300002h
CONFIG2L
—
—
—
BORV1
BORV0
BOREN1
—
—
—
WDTPS3
WDTPS2
—
—
—
Bit 1
Bit 0
FOSC1
FOSC0
BOREN0 PWRTEN
Default/
Unprogrammed
Value
00-- 0111
---1 1111
WDTPS1 WDTPS0
WDTEN
HFOFST LPT1OSC PBADEN
CCP2MX
1--- 1011
—
STVREN
10-- -1-1
CP2(1)
CP1
CP0
---- 1111
—
—
—
—
11-- ----
—
WRT3(1)
WRT2(1)
WRT1
WRT0
---- 1111
—
—
—
—
—
111- ----
300003h
CONFIG2H
300005h
CONFIG3H MCLRE
300006h
CONFIG4L
DEBUG
XINST
—
—
—
LVP
300008h
CONFIG5L
—
—
—
—
CP3(1)
300009h
CONFIG5H
CPD
CPB
—
—
30000Ah
CONFIG6L
—
—
—
30000Bh
CONFIG6H
WRTD
WRTB
WRTC
(1)
(1)
---1 1111
30000Ch
CONFIG7L
—
—
—
—
EBTR1
EBTR0
---- 1111
30000Dh
CONFIG7H
—
EBTRB
—
—
—
—
—
—
-1-- ----
DEV2
DEV1
DEV0
REV4
REV3
REV2
REV1
REV0
qqqq qqqq(2)
DEV10
DEV9
DEV8
DEV7
DEV6
DEV5
DEV4
DEV3
0000 1100
3FFFFEh DEVID1(2)
(2)
EBTR3
EBTR2
3FFFFFh
DEVID2
Legend:
x = unknown, u = unchanged, – = unimplemented, q = value depends on condition.
Shaded cells are unimplemented, read as ‘0’.
Implemented but not used in PIC18FX3K20 and PIC18FX4K20 devices; maintain this bit set.
See Register 23-12 for DEVID1 values. DEVID registers are read-only and cannot be programmed by the user.
Note 1:
2:
DS41303G-page 300
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 23-1:
CONFIG1H: CONFIGURATION REGISTER 1 HIGH
R/P-0
R/P-0
U-0
U-0
R/P-0
R/P-1
R/P-1
R/P-1
IESO
FCMEN
—
—
FOSC3
FOSC2
FOSC1
FOSC0
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
x = Bit is unknown
bit 7
IESO: Internal/External Oscillator Switchover bit
1 = Oscillator Switchover mode enabled
0 = Oscillator Switchover mode disabled
bit 6
FCMEN: Fail-Safe Clock Monitor Enable bit
1 = Fail-Safe Clock Monitor enabled
0 = Fail-Safe Clock Monitor disabled
bit 5-4
Unimplemented: Read as ‘0’
bit 3-0
FOSC<3:0>: Oscillator Selection bits
11xx = External RC oscillator, CLKOUT function on RA6
101x = External RC oscillator, CLKOUT function on RA6
1001 = Internal oscillator block, CLKOUT function on RA6, port function on RA7
1000 = Internal oscillator block, port function on RA6 and RA7
0111 = External RC oscillator, port function on RA6
0110 = HS oscillator, PLL enabled (Clock Frequency = 4 x FOSC1)
0101 = EC oscillator, port function on RA6
0100 = EC oscillator, CLKOUT function on RA6
0011 = External RC oscillator, CLKOUT function on RA6
0010 = HS oscillator
0001 = XT oscillator
0000 = LP oscillator
 2010 Microchip Technology Inc.
DS41303G-page 301
PIC18F2XK20/4XK20
REGISTER 23-2:
CONFIG2L: CONFIGURATION REGISTER 2 LOW
U-0
U-0
U-0
R/P-1
R/P-1
R/P-1
R/P-1
R/P-1
—
—
—
BORV1(1)
BORV0(1)
BOREN1(2)
BOREN0(2)
PWRTEN(2)
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
x = Bit is unknown
bit 7-5
Unimplemented: Read as ‘0’
bit 4-3
BORV<1:0>: Brown-out Reset Voltage bits(1)
11 = VBOR set to 1.8V nominal
10 = VBOR set to 2.2V nominal
01 = VBOR set to 2.7V nominal
00 = VBOR set to 3.0V nominal
bit 2-1
BOREN<1:0>: Brown-out Reset Enable bits(2)
11 = Brown-out Reset enabled in hardware only (SBOREN is disabled)
10 = Brown-out Reset enabled in hardware only and disabled in Sleep mode
(SBOREN is disabled)
01 = Brown-out Reset enabled and controlled by software (SBOREN is enabled)
00 = Brown-out Reset disabled in hardware and software
bit 0
PWRTEN: Power-up Timer Enable bit(2)
1 = PWRT disabled
0 = PWRT enabled
Note
1:
2:
See Section 26.1 “DC Characteristics: Supply Voltage” for specifications.
The Power-up Timer is decoupled from Brown-out Reset, allowing these features to be independently controlled.
REGISTER 23-3:
CONFIG2H: CONFIGURATION REGISTER 2 HIGH
U-0
U-0
U-0
R/P-1
R/P-1
R/P-1
R/P-1
R/P-1
—
—
—
WDTPS3
WDTPS2
WDTPS1
WDTPS0
WDTEN
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
x = Bit is unknown
bit 7-5
Unimplemented: Read as ‘0’
bit 4-1
WDTPS<3:0>: Watchdog Timer Postscale Select bits
1111 = 1:32,768
1110 = 1:16,384
1101 = 1:8,192
1100 = 1:4,096
1011 = 1:2,048
1010 = 1:1,024
1001 = 1:512
1000 = 1:256
0111 = 1:128
0110 = 1:64
0101 = 1:32
0100 = 1:16
0011 = 1:8
0010 = 1:4
0001 = 1:2
0000 = 1:1
bit 0
WDTEN: Watchdog Timer Enable bit
1 = WDT is always enabled. SWDTEN bit has no effect
0 = WDT is controlled by SWDTEN bit of the WDTCON register
DS41303G-page 302
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 23-4:
CONFIG3H: CONFIGURATION REGISTER 3 HIGH
R/P-1
U-0
U-0
U-0
R/P-1
R/P-0
R/P-1
R/P-1
MCLRE
—
—
—
HFOFST
LPT1OSC
PBADEN
CCP2MX
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
x = Bit is unknown
bit 7
MCLRE: MCLR Pin Enable bit
1 = MCLR pin enabled; RE3 input pin disabled
0 = RE3 input pin enabled; MCLR disabled
bit 6-4
Unimplemented: Read as ‘0’
bit 3
HFOFST: HFINTOSC Fast Start-up
1 = HFINTOSC starts clocking the CPU without waiting for the oscillator to stabilize.
0 = The system clock is held off until the HFINTOSC is stable.
bit 2
LPT1OSC: Low-Power Timer1 Oscillator Enable bit
1 = Timer1 configured for low-power operation
0 = Timer1 configured for higher power operation
bit 1
PBADEN: PORTB A/D Enable bit
(Affects ANSELH Reset state. ANSELH controls PORTB<4:0> pin configuration.)
1 = PORTB<4:0> pins are configured as analog input channels on Reset
0 = PORTB<4:0> pins are configured as digital I/O on Reset
bit 0
CCP2MX: CCP2 MUX bit
1 = CCP2 input/output is multiplexed with RC1
0 = CCP2 input/output is multiplexed with RB3
REGISTER 23-5:
R/P-1
CONFIG4L: CONFIGURATION REGISTER 4 LOW
R/P-0
DEBUG
XINST
U-0
U-0
—
—
U-0
—
R/P-1
LVP
(1)
U-0
R/P-1
—
STVREN
bit 0
bit 7
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
x = Bit is unknown
bit 7
DEBUG: Background Debugger Enable bit
1 = Background debugger disabled, RB6 and RB7 configured as general purpose I/O pins
0 = Background debugger enabled, RB6 and RB7 are dedicated to In-Circuit Debug
bit 6
XINST: Extended Instruction Set Enable bit
1 = Instruction set extension and Indexed Addressing mode enabled
0 = Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
bit 5-3
Unimplemented: Read as ‘0’
bit 2
LVP: Single-Supply ICSP Enable bit
1 = Single-Supply ICSP enabled
0 = Single-Supply ICSP disabled
bit 1
Unimplemented: Read as ‘0’
bit 0
STVREN: Stack Full/Underflow Reset Enable bit
1 = Stack full/underflow will cause Reset
0 = Stack full/underflow will not cause Reset
Note 1:
Can only be changed by a programmer in high-voltage programming mode.
 2010 Microchip Technology Inc.
DS41303G-page 303
PIC18F2XK20/4XK20
REGISTER 23-6:
U-0
CONFIG5L: CONFIGURATION REGISTER 5 LOW
U-0
—
—
U-0
—
U-0
—
R/C-1
R/C-1
(1)
(1)
CP3
CP2
R/C-1
R/C-1
CP1
CP0
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7-4
Unimplemented: Read as ‘0’
bit 3
CP3: Code Protection bit(1)
1 = Block 3 not code-protected
0 = Block 3 code-protected
bit 2
CP2: Code Protection bit(1)
1 = Block 2 not code-protected
0 = Block 2 code-protected
bit 1
CP1: Code Protection bit
1 = Block 1 not code-protected
0 = Block 1 code-protected
bit 0
CP0: Code Protection bit
1 = Block 0 not code-protected
0 = Block 0 code-protected
Note 1:
Implemented, but not used in PIC18FX3K20 and PIC18FX4K20 devices.
REGISTER 23-7:
CONFIG5H: CONFIGURATION REGISTER 5 HIGH
R/C-1
R/C-1
U-0
U-0
U-0
U-0
U-0
U-0
CPD
CPB
—
—
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7
CPD: Data EEPROM Code Protection bit
1 = Data EEPROM not code-protected
0 = Data EEPROM code-protected
bit 6
CPB: Boot Block Code Protection bit
1 = Boot Block not code-protected
0 = Boot Block code-protected
bit 5-0
Unimplemented: Read as ‘0’
DS41303G-page 304
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 23-8:
CONFIG6L: CONFIGURATION REGISTER 6 LOW
U-0
U-0
U-0
U-0
R/C-1
R/C-1
R/C-1
R/C-1
—
—
—
—
WRT3(1)
WRT2(1)
WRT1
WRT0
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7-4
Unimplemented: Read as ‘0’
bit 3
WRT3: Write Protection bit(1)
1 = Block 3 not write-protected
0 = Block 3 write-protected
bit 2
WRT2: Write Protection bit(1)
1 = Block 2 not write-protected
0 = Block 2 write-protected
bit 1
WRT1: Write Protection bit
1 = Block 1 not write-protected
0 = Block 1 write-protected
bit 0
WRT0: Write Protection bit
1 = Block 0 not write-protected
0 = Block 0 write-protected
Note 1:
Implemented, but not used in PIC18FX3K20 and PIC18FX4K20 devices.
REGISTER 23-9:
R/C-1
WRTD
CONFIG6H: CONFIGURATION REGISTER 6 HIGH
R/C-1
R-1
U-0
U-0
U-0
U-0
U-0
WRTB
WRTC(1)
—
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7
WRTD: Data EEPROM Write Protection bit
1 = Data EEPROM not write-protected
0 = Data EEPROM write-protected
bit 6
WRTB: Boot Block Write Protection bit
1 = Boot Block not write-protected
0 = Boot Block write-protected
bit 5
WRTC: Configuration Register Write Protection bit(1)
1 = Configuration registers not write-protected
0 = Configuration registers write-protected
bit 4-0
Unimplemented: Read as ‘0’
Note 1:
This bit is read-only in normal execution mode; it can be written only in Program mode.
 2010 Microchip Technology Inc.
DS41303G-page 305
PIC18F2XK20/4XK20
REGISTER 23-10: CONFIG7L: CONFIGURATION REGISTER 7 LOW
U-0
U-0
U-0
U-0
R/C-1
R/C-1
R/C-1
R/C-1
—
—
—
—
EBTR3(1)
EBTR2(1)
EBTR1
EBTR0
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7-4
Unimplemented: Read as ‘0’
bit 3
EBTR3: Table Read Protection bit(1)
1 = Block 3 not protected from table reads executed in other blocks
0 = Block 3 protected from table reads executed in other blocks
bit 2
EBTR2: Table Read Protection bit(1)
1 = Block 2 not protected from table reads executed in other blocks
0 = Block 2 protected from table reads executed in other blocks
bit 1
EBTR1: Table Read Protection bit
1 = Block 1 not protected from table reads executed in other blocks
0 = Block 1 protected from table reads executed in other blocks
bit 0
EBTR0: Table Read Protection bit
1 = Block 0 not protected from table reads executed in other blocks
0 = Block 0 protected from table reads executed in other blocks
Note 1:
Implemented, but not used in PIC18FX3K20 and PIC18FX4K20 devices.
REGISTER 23-11: CONFIG7H: CONFIGURATION REGISTER 7 HIGH
U-0
R/C-1
U-0
U-0
U-0
U-0
U-0
U-0
—
EBTRB
—
—
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7
Unimplemented: Read as ‘0’
bit 6
EBTRB: Boot Block Table Read Protection bit
1 = Boot Block not protected from table reads executed in other blocks
0 = Boot Block protected from table reads executed in other blocks
bit 5-0
Unimplemented: Read as ‘0’
DS41303G-page 306
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
REGISTER 23-12: DEVID1: DEVICE ID REGISTER 1 FOR PIC18F2XK20/4XK20
R
R
R
R
R
R
R
R
DEV2
DEV1
DEV0
REV4
REV3
REV2
REV1
REV0
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7-5
DEV<2:0>: Device ID bits
000 = PIC18F46K20
001 = PIC18F26K20
010 = PIC18F45K20
011 = PIC18F25K20
100 = PIC18F44K20
101 = PIC18F24K20
110 = PIC18F43K20
111 = PIC18F23K20
bit 4-0
REV<4:0>: Revision ID bits
These bits are used to indicate the device revision.
REGISTER 23-13: DEVID2: DEVICE ID REGISTER 2 FOR PIC18F2XK20/4XK20
R
R
R
R
R
R
R
R
DEV10
DEV9
DEV8
DEV7
DEV6
DEV5
DEV4
DEV3
bit 7
bit 0
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
C = Clearable only bit
bit 7-0
Note 1:
DEV<10:3>: Device ID bits
These bits are used with the DEV<2:0> bits in the Device ID Register 1 to identify the
part number.
0010 0000 = PIC18F2XK20/4XK20 devices
These values for DEV<10:3> may be shared with other devices. The specific device is always identified
by using the entire DEV<10:0> bit sequence.
 2010 Microchip Technology Inc.
DS41303G-page 307
PIC18F2XK20/4XK20
23.2
Watchdog Timer (WDT)
For PIC18F2XK20/4XK20 devices, the WDT is driven
by the LFINTOSC source. When the WDT is enabled,
the clock source is also enabled. The nominal WDT
period is 4 ms and has the same stability as the LFINTOSC oscillator.
The 4 ms period of the WDT is multiplied by a 16-bit
postscaler. Any output of the WDT postscaler is
selected by a multiplexer, controlled by bits in Configuration Register 2H. Available periods range from 4 ms
to 131.072 seconds (2.18 minutes). The WDT and
postscaler are cleared when any of the following events
occur: a SLEEP or CLRWDT instruction is executed, the
IRCF bits of the OSCCON register are changed or a
clock failure has occurred.
Note 1: The CLRWDT and SLEEP instructions
clear the WDT and postscaler counts
when executed.
2: Changing the setting of the IRCF bits of
the OSCCON register clears the WDT
and postscaler counts.
3: When a CLRWDT instruction is executed,
the postscaler count will be cleared.
FIGURE 23-1:
WDT BLOCK DIAGRAM
SWDTEN
WDTEN
Enable WDT
WDT Counter
LFINTOSC Source
128
Wake-up
from Power
Managed Modes
Change on IRCF bits
Programmable Postscaler
1:1 to 1:32,768
CLRWDT
Reset
WDT
Reset
All Device Resets
WDTPS<3:0>
4
Sleep
DS41303G-page 308
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
23.2.1
CONTROL REGISTER
Register 23-14 shows the WDTCON register. This is a
readable and writable register which contains a control
bit that allows software to override the WDT enable
Configuration bit, but only if the Configuration bit has
disabled the WDT.
REGISTER 23-14: WDTCON: WATCHDOG TIMER CONTROL REGISTER
U-0
U-0
U-0
U-0
U-0
U-0
U-0
R/W-0
—
—
—
—
—
—
—
SWDTEN(1)
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-1
Unimplemented: Read as ‘0’
bit 0
SWDTEN: Software Enable or Disable the Watchdog Timer bit(1)
1 = WDT is turned on
0 = WDT is turned off (Reset value)
x = Bit is unknown
Note 1: This bit has no effect if the Configuration bit, WDTEN, is enabled.
TABLE 23-2:
Name
RCON
WDTCON
SUMMARY OF WATCHDOG TIMER REGISTERS
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
IPEN
SBOREN
—
RI
TO
PD
POR
BOR
58
—
—
—
—
—
—
—
SWDTEN
60
WDTEN
302
CONFIG2H
WDTPS3 WDTPS2 WDTPS1 WDTPS0
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Watchdog Timer.
 2010 Microchip Technology Inc.
DS41303G-page 309
PIC18F2XK20/4XK20
23.3
Program Verification and
Code Protection
Each of the blocks has three code protection bits associated with them. They are:
The overall structure of the code protection on the
PIC18 Flash devices differs significantly from other
PIC® microcontroller devices.
The user program memory is divided into three or five
blocks, depending on the device. One of these is a
Boot Block of 0.5K or 2K bytes, depending on the
device. The remainder of the memory is divided into
individual blocks on binary boundaries.
FIGURE 23-2:
• Code-Protect bit (CPn)
• Write-Protect bit (WRTn)
• External Block Table Read bit (EBTRn)
Figure 23-2 shows the program memory organization
for 8, 16 and 32-Kbyte devices and the specific code
protection bit associated with each block. The actual
locations of the bits are summarized in Table 23-3.
CODE-PROTECTED PROGRAM MEMORY FOR PIC18F2XK20/4XK20
MEMORY SIZE/DEVICE
Block Code Protection
Controlled By:
8 Kbytes
(PIC18FX3K20)
16 Kbytes
(PIC18FX4K20)
32 Kbytes
(PIC18FX5K20)
64 Kbytes
(PIC18FX6K20)
Boot Block
(000h-1FFh)
Boot Block
(000h-7FFh)
Boot Block
(000h-7FFh)
Boot Block
(000h-7FFh)
CPB, WRTB, EBTRB
Block 0
(200h-FFFh)
Block 0
(800h-1FFFh)
Block 0
(800h-1FFFh)
Block 0
(800h-3FFFh)
CP0, WRT0, EBTR0
Block 1
(1000h-1FFFh)
Block 1
(2000h-3FFFh)
Block 1
(2000h-3FFFh)
Block 1
(4000h-7FFFh)
CP1, WRT1, EBTR1
Block 2
(4000h-5FFFh)
Block 2
(8000h-BFFFh)
CP2, WRT2, EBTR2
Block 3
(6000h-7FFFh)
Block 3
(C000h-FFFFh)
CP3, WRT3, EBTR3
Unimplemented
Read ‘0’s
(2000h-1FFFFFh)
Unimplemented
Read ‘0’s
(4000h-1FFFFFh)
Unimplemented
Unimplemented
Read ‘0’s
Read ‘0’s
(8000h-1FFFFFh) (10000h-1FFFFFh)
TABLE 23-3:
(Unimplemented
Memory Space)
SUMMARY OF CODE PROTECTION REGISTERS
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
CP3(1)
CP2(1)
CP1
CP0
300008h
CONFIG5L
—
—
—
—
300009h
CONFIG5H
CPD
CPB
—
—
—
—
—
—
30000Ah
CONFIG6L
—
—
—
—
WRT3(1)
WRT2(1)
WRT1
WRT0
30000Bh
CONFIG6H
WRTD
WRTB
WRTC
—
—
—
—
—
30000Ch
CONFIG7L
—
—
—
—
EBTR3(1)
EBTR2(1)
EBTR1
EBTR0
30000Dh
CONFIG7H
—
EBTRB
—
—
—
—
—
—
Legend: Shaded cells are unimplemented.
Note 1: Implemented, but not used in PIC18FX3K20 and PIC18FX4K20 devices.
DS41303G-page 310
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
23.3.1
PROGRAM MEMORY
CODE PROTECTION
The program memory may be read to or written from
any location using the table read and table write
instructions. The device ID may be read with table
reads. The Configuration registers may be read and
written with the table read and table write instructions.
instruction that executes from a location outside of that
block is not allowed to read and will result in reading ‘0’s.
Figures 23-3 through 23-5 illustrate table write and table
read protection.
Note:
In normal execution mode, the CPn bits have no direct
effect. CPn bits inhibit external reads and writes. A block
of user memory may be protected from table writes if the
WRTn Configuration bit is ‘0’. The EBTRn bits control
table reads. For a block of user memory with the EBTRn
bit cleared to ‘0’, a table READ instruction that executes
from within that block is allowed to read. A table read
FIGURE 23-3:
Code protection bits may only be written to
a ‘0’ from a ‘1’ state. It is not possible to
write a ‘1’ to a bit in the ‘0’ state. Code protection bits are only set to ‘1’ by a full chip
erase or block erase function. The full chip
erase and block erase functions can only
be initiated via ICSP or an external
programmer.
TABLE WRITE (WRTn) DISALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
0007FFh
000800h
WRTB, EBTRB = 11
TBLPTR = 0008FFh
WRT0, EBTR0 = 01
PC = 001FFEh
TBLWT*
001FFFh
002000h
WRT1, EBTR1 = 11
003FFFh
004000h
PC = 005FFEh
WRT2, EBTR2 = 11
TBLWT*
005FFFh
006000h
WRT3, EBTR3 = 11
007FFFh
Results: All table writes disabled to Blockn whenever WRTn = 0.
 2010 Microchip Technology Inc.
DS41303G-page 311
PIC18F2XK20/4XK20
FIGURE 23-4:
EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
0007FFh
000800h
WRTB, EBTRB = 11
TBLPTR = 0008FFh
WRT0, EBTR0 = 10
001FFFh
002000h
PC = 003FFEh
TBLRD*
WRT1, EBTR1 = 11
003FFFh
004000h
WRT2, EBTR2 = 11
005FFFh
006000h
WRT3, EBTR3 = 11
007FFFh
Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0.
TABLAT register returns a value of ‘0’.
FIGURE 23-5:
EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
WRTB, EBTRB = 11
0007FFh
000800h
TBLPTR = 0008FFh
PC = 001FFEh
WRT0, EBTR0 = 10
TBLRD*
001FFFh
002000h
WRT1, EBTR1 = 11
003FFFh
004000h
WRT2, EBTR2 = 11
005FFFh
006000h
WRT3, EBTR3 = 11
007FFFh
Results: Table reads permitted within Blockn, even when EBTRBn = 0.
TABLAT register returns the value of the data at the location TBLPTR.
DS41303G-page 312
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
23.3.2
DATA EEPROM
CODE PROTECTION
The entire data EEPROM is protected from external
reads and writes by two bits: CPD and WRTD. CPD
inhibits external reads and writes of data EEPROM.
WRTD inhibits internal and external writes to data
EEPROM. The CPU can always read data EEPROM
under normal operation, regardless of the protection bit
settings.
23.3.3
CONFIGURATION REGISTER
PROTECTION
The Configuration registers can be write-protected.
The WRTC bit controls protection of the Configuration
registers. In normal execution mode, the WRTC bit is
readable only. WRTC can only be written via ICSP or
an external programmer.
23.4
ID Locations
Eight memory locations (200000h-200007h) are
designated as ID locations, where the user can store
checksum or other code identification numbers. These
locations are both readable and writable during normal
execution through the TBLRD and TBLWT instructions
or during program/verify. The ID locations can be read
when the device is code-protected.
23.5
In-Circuit Serial Programming
PIC18F2XK20/4XK20 devices can be serially
programmed while in the end application circuit. This is
simply done with two lines for clock and data and three
other lines for power, ground and the programming
voltage. This allows customers to manufacture boards
with unprogrammed devices and then program the
microcontroller just before shipping the product. This
also allows the most recent firmware or a custom
firmware to be programmed.
23.6
In-Circuit Debugger
When the DEBUG Configuration bit is programmed to
a ‘0’, the In-Circuit Debugger functionality is enabled.
This function allows simple debugging functions when
used with MPLAB® IDE. When the microcontroller has
this feature enabled, some resources are not available
for general use. Table 23-4 shows which resources are
required by the background debugger.
TABLE 23-4:
DEBUGGER RESOURCES
I/O pins:
RB6, RB7
Stack:
2 levels
Program Memory:
512 bytes
Data Memory:
10 bytes
 2010 Microchip Technology Inc.
To use the In-Circuit Debugger function of the microcontroller, the design must implement In-Circuit Serial
Programming connections to the following pins:
•
•
•
•
•
MCLR/VPP/RE3
VDD
VSS
RB7
RB6
This will interface to the In-Circuit Debugger module
available from Microchip or one of the third party development tool companies.
23.7
Single-Supply ICSP Programming
The LVP Configuration bit enables Single-Supply ICSP
Programming (formerly known as Low-Voltage ICSP
Programming or LVP). When Single-Supply Programming is enabled, the microcontroller can be programmed
without requiring high voltage being applied to the
MCLR/VPP/RE3 pin, but the RB5/KBI1/PGM pin is then
dedicated to controlling Program mode entry and is not
available as a general purpose I/O pin.
While programming, using Single-Supply Programming
mode, VDD is applied to the MCLR/VPP/RE3 pin as in
normal execution mode. To enter Programming mode,
VDD is applied to the PGM pin.
Note 1: High-voltage programming is always
available, regardless of the state of the
LVP bit or the PGM pin, by applying VIHH
to the MCLR pin.
2: By default, Single-Supply ICSP is
enabled in unprogrammed devices (as
supplied from Microchip) and erased
devices.
3: When Single-Supply Programming is
enabled, the RB5 pin can no longer be
used as a general purpose I/O pin.
4: When LVP is enabled, externally pull the
PGM pin to VSS to allow normal program
execution.
If Single-Supply ICSP Programming mode will not be
used, the LVP bit can be cleared. RB5/KBI1/PGM then
becomes available as the digital I/O pin, RB5. The LVP
bit may be set or cleared only when using standard
high-voltage programming (VIHH applied to the MCLR/
VPP/RE3 pin). Once LVP has been disabled, only the
standard high-voltage programming is available and
must be used to program the device.
Memory that is not code-protected can be erased using
either a block erase, or erased row by row, then written
at any specified VDD. If code-protected memory is to be
erased, a block erase is required.
DS41303G-page 313
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 314
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
24.0
INSTRUCTION SET SUMMARY
PIC18F2XK20/4XK20 devices incorporate the standard
set of 75 PIC18 core instructions, as well as an extended
set of 8 new instructions, for the optimization of code that
is recursive or that utilizes a software stack. The
extended set is discussed later in this section.
24.1
Standard Instruction Set
The standard PIC18 instruction set adds many
enhancements to the previous PIC® MCU instruction
sets, while maintaining an easy migration from these
PIC® MCU instruction sets. Most instructions are a single program memory word (16 bits), but there are four
instructions that require two program memory locations.
Each single-word instruction is a 16-bit word divided
into an opcode, which specifies the instruction type and
one or more operands, which further specify the
operation of the instruction.
The instruction set is highly orthogonal and is grouped
into four basic categories:
•
•
•
•
Byte-oriented operations
Bit-oriented operations
Literal operations
Control operations
The PIC18 instruction set summary in Table 24-2 lists
byte-oriented, bit-oriented, literal and control
operations. Table 24-1 shows the opcode field
descriptions.
Most byte-oriented instructions have three operands:
1.
2.
3.
The file register (specified by ‘f’)
The destination of the result (specified by ‘d’)
The accessed memory (specified by ‘a’)
The file register designator ‘f’ specifies which file
register is to be used by the instruction. The destination
designator ‘d’ specifies where the result of the operation is to be placed. If ‘d’ is zero, the result is placed in
the WREG register. If ‘d’ is one, the result is placed in
the file register specified in the instruction.
All bit-oriented instructions have three operands:
1.
2.
3.
The file register (specified by ‘f’)
The bit in the file register (specified by ‘b’)
The accessed memory (specified by ‘a’)
The literal instructions may use some of the following
operands:
• A literal value to be loaded into a file register
(specified by ‘k’)
• The desired FSR register to load the literal value
into (specified by ‘f’)
• No operand required
(specified by ‘—’)
The control instructions may use some of the following
operands:
• A program memory address (specified by ‘n’)
• The mode of the CALL or RETURN instructions
(specified by ‘s’)
• The mode of the table read and table write
instructions (specified by ‘m’)
• No operand required
(specified by ‘—’)
All instructions are a single word, except for four
double-word instructions. These instructions were
made double-word to contain the required information
in 32 bits. In the second word, the 4 MSbs are ‘1’s. If
this second word is executed as an instruction (by
itself), it will execute as a NOP.
All single-word instructions are executed in a single
instruction cycle, unless a conditional test is true or the
program counter is changed as a result of the instruction. In these cases, the execution takes two instruction
cycles, with the additional instruction cycle(s) executed
as a NOP.
The double-word instructions execute in two instruction
cycles.
One instruction cycle consists of four oscillator periods.
Thus, for an oscillator frequency of 4 MHz, the normal
instruction execution time is 1 s. If a conditional test is
true, or the program counter is changed as a result of
an instruction, the instruction execution time is 2 s.
Two-word branch instructions (if true) would take 3 s.
Figure 24-1 shows the general formats that the instructions can have. All examples use the convention ‘nnh’
to represent a hexadecimal number.
The Instruction Set Summary, shown in Table 24-2,
lists the standard instructions recognized by the
Microchip Assembler (MPASMTM).
Section 24.1.1 “Standard Instruction Set” provides
a description of each instruction.
The bit field designator ‘b’ selects the number of the bit
affected by the operation, while the file register
designator ‘f’ represents the number of the file in which
the bit is located.
 2010 Microchip Technology Inc.
DS41303G-page 315
PIC18F2XK20/4XK20
TABLE 24-1:
OPCODE FIELD DESCRIPTIONS
Field
Description
a
RAM access bit
a = 0: RAM location in Access RAM (BSR register is ignored)
a = 1: RAM bank is specified by BSR register
bbb
Bit address within an 8-bit file register (0 to 7).
BSR
Bank Select Register. Used to select the current RAM bank.
C, DC, Z, OV, N
ALU Status bits: Carry, Digit Carry, Zero, Overflow, Negative.
d
Destination select bit
d = 0: store result in WREG
d = 1: store result in file register f
dest
Destination: either the WREG register or the specified register file location.
f
8-bit Register file address (00h to FFh) or 2-bit FSR designator (0h to 3h).
fs
12-bit Register file address (000h to FFFh). This is the source address.
fd
12-bit Register file address (000h to FFFh). This is the destination address.
GIE
Global Interrupt Enable bit.
k
Literal field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value).
label
Label name.
mm
The mode of the TBLPTR register for the table read and table write instructions.
Only used with table read and table write instructions:
*
No change to register (such as TBLPTR with table reads and writes)
*+
Post-Increment register (such as TBLPTR with table reads and writes)
*-
Post-Decrement register (such as TBLPTR with table reads and writes)
Pre-Increment register (such as TBLPTR with table reads and writes)
+*
n
The relative address (2’s complement number) for relative branch instructions or the direct address for
CALL/BRANCH and RETURN instructions.
PC
Program Counter.
PCL
Program Counter Low Byte.
PCH
Program Counter High Byte.
PCLATH
Program Counter High Byte Latch.
PCLATU
Program Counter Upper Byte Latch.
PD
Power-down bit.
PRODH
Product of Multiply High Byte.
PRODL
Product of Multiply Low Byte.
s
Fast Call/Return mode select bit
s = 0: do not update into/from shadow registers
s = 1: certain registers loaded into/from shadow registers (Fast mode)
TBLPTR
21-bit Table Pointer (points to a Program Memory location).
TABLAT
8-bit Table Latch.
TO
Time-out bit.
TOS
Top-of-Stack.
u
Unused or unchanged.
WDT
Watchdog Timer.
WREG
Working register (accumulator).
x
Don’t care (‘0’ or ‘1’). The assembler will generate code with x = 0. It is the recommended form of use for
compatibility with all Microchip software tools.
zs
7-bit offset value for indirect addressing of register files (source).
7-bit offset value for indirect addressing of register files (destination).
zd
{
}
Optional argument.
[text]
Indicates an indexed address.
(text)
The contents of text.
[expr]<n>
Specifies bit n of the register indicated by the pointer expr.

Assigned to.
< >
Register bit field.

In the set of.
italics
User defined term (font is Courier).
DS41303G-page 316
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 24-1:
GENERAL FORMAT FOR INSTRUCTIONS
Byte-oriented file register operations
15
10
9 8 7
OPCODE d
a
Example Instruction
0
f (FILE #)
ADDWF MYREG, W, B
d = 0 for result destination to be WREG register
d = 1 for result destination to be file register (f)
a = 0 to force Access Bank
a = 1 for BSR to select bank
f = 8-bit file register address
Byte to Byte move operations (2-word)
15
12 11
OPCODE
15
0
f (Source FILE #)
12 11
MOVFF MYREG1, MYREG2
0
f (Destination FILE #)
1111
f = 12-bit file register address
Bit-oriented file register operations
15
12 11
9 8 7
OPCODE b (BIT #) a
0
f (FILE #)
BSF MYREG, bit, B
b = 3-bit position of bit in file register (f)
a = 0 to force Access Bank
a = 1 for BSR to select bank
f = 8-bit file register address
Literal operations
15
8
7
OPCODE
0
k (literal)
MOVLW 7Fh
k = 8-bit immediate value
Control operations
CALL, GOTO and Branch operations
15
8 7
OPCODE
15
0
n<7:0> (literal)
12 11
GOTO Label
0
n<19:8> (literal)
1111
n = 20-bit immediate value
15
8 7
OPCODE
15
S
0
CALL MYFUNC
n<7:0> (literal)
12 11
0
n<19:8> (literal)
1111
S = Fast bit
15
OPCODE
15
OPCODE
 2010 Microchip Technology Inc.
11 10
0
BRA MYFUNC
n<10:0> (literal)
8 7
n<7:0> (literal)
0
BC MYFUNC
DS41303G-page 317
PIC18F2XK20/4XK20
TABLE 24-2:
PIC18FXXXX INSTRUCTION SET
16-Bit Instruction Word
Mnemonic,
Operands
Description
Cycles
MSb
LSb
Status
Affected
Notes
BYTE-ORIENTED OPERATIONS
ADDWF
ADDWFC
ANDWF
CLRF
COMF
CPFSEQ
CPFSGT
CPFSLT
DECF
DECFSZ
DCFSNZ
INCF
INCFSZ
INFSNZ
IORWF
MOVF
MOVFF
f, d, a
f, d, a
f, d, a
f, a
f, d, a
f, a
f, a
f, a
f, d, a
f, d, a
f, d, a
f, d, a
f, d, a
f, d, a
f, d, a
f, d, a
fs, fd
MOVWF
MULWF
NEGF
RLCF
RLNCF
RRCF
RRNCF
SETF
SUBFWB
f, a
f, a
f, a
f, d, a
f, d, a
f, d, a
f, d, a
f, a
f, d, a
SUBWF
SUBWFB
f, d, a
f, d, a
SWAPF
TSTFSZ
XORWF
f, d, a
f, a
f, d, a
Note 1:
When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value
present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is driven low by an
external device, the data will be written back with a ‘0’.
If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared if
assigned.
If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is
executed as a NOP.
Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the
first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory
locations have a valid instruction.
2:
3:
4:
Add WREG and f
Add WREG and CARRY bit to f
AND WREG with f
Clear f
Complement f
Compare f with WREG, skip =
Compare f with WREG, skip >
Compare f with WREG, skip <
Decrement f
Decrement f, Skip if 0
Decrement f, Skip if Not 0
Increment f
Increment f, Skip if 0
Increment f, Skip if Not 0
Inclusive OR WREG with f
Move f
Move fs (source) to 1st word
fd (destination) 2nd word
Move WREG to f
Multiply WREG with f
Negate f
Rotate Left f through Carry
Rotate Left f (No Carry)
Rotate Right f through Carry
Rotate Right f (No Carry)
Set f
Subtract f from WREG with
borrow
Subtract WREG from f
Subtract WREG from f with
borrow
Swap nibbles in f
Test f, skip if 0
Exclusive OR WREG with f
DS41303G-page 318
1
1
1
1
1
1 (2 or 3)
1 (2 or 3)
1 (2 or 3)
1
1 (2 or 3)
1 (2 or 3)
1
1 (2 or 3)
1 (2 or 3)
1
1
2
C, DC, Z, OV, N
C, DC, Z, OV, N
Z, N
Z
Z, N
None
None
None
C, DC, Z, OV, N
None
None
C, DC, Z, OV, N
None
None
Z, N
Z, N
None
1, 2
1, 2
1,2
2
1, 2
4
4
1, 2
1, 2, 3, 4
1, 2, 3, 4
1, 2
1, 2, 3, 4
4
1, 2
1, 2
1
1
1
1
1
1
1
1
1
1
0010 01da0
0010 0da
0001 01da
0110 101a
0001 11da
0110 001a
0110 010a
0110 000a
0000 01da
0010 11da
0100 11da
0010 10da
0011 11da
0100 10da
0001 00da
0101 00da
1100 ffff
1111 ffff
0110 111a
0000 001a
0110 110a
0011 01da
0100 01da
0011 00da
0100 00da
0110 100a
0101 01da
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
1
1
0101
0101
11da
10da
ffff
ffff
ffff C, DC, Z, OV, N
ffff C, DC, Z, OV, N
1, 2
1
1 (2 or 3)
1
0011
0110
0001
10da
011a
10da
ffff
ffff
ffff
ffff None
ffff None
ffff Z, N
4
1, 2
None
None
C, DC, Z, OV, N
C, Z, N
Z, N
C, Z, N
Z, N
None
C, DC, Z, OV, N
1, 2
1, 2
1, 2
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 24-2:
PIC18FXXXX INSTRUCTION SET (CONTINUED)
16-Bit Instruction Word
Mnemonic,
Operands
Description
Cycles
MSb
LSb
Status
Affected
Notes
BIT-ORIENTED OPERATIONS
BCF
BSF
BTFSC
BTFSS
BTG
f, b, a
f, b, a
f, b, a
f, b, a
f, d, a
Bit Clear f
Bit Set f
Bit Test f, Skip if Clear
Bit Test f, Skip if Set
Bit Toggle f
1
1
1 (2 or 3)
1 (2 or 3)
1
1001
1000
1011
1010
0111
bbba
bbba
bbba
bbba
bbba
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
None
None
None
None
None
1 (2)
1 (2)
1 (2)
1 (2)
1 (2)
1 (2)
1 (2)
2
1 (2)
2
0010
0110
0011
0111
0101
0001
0100
0nnn
0000
110s
kkkk
0000
0000
1111
kkkk
0000
xxxx
0000
0000
1nnn
0000
0000
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
kkkk
kkkk
0000
0000
kkkk
kkkk
0000
xxxx
0000
0000
nnnn
1111
0001
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
kkkk
kkkk
0100
0111
kkkk
kkkk
0000
xxxx
0110
0101
nnnn
1111
000s
None
None
None
None
None
None
None
None
None
None
1
1
1
1
2
1
2
1110
1110
1110
1110
1110
1110
1110
1101
1110
1110
1111
0000
0000
1110
1111
0000
1111
0000
0000
1101
0000
0000
2
2
1
0000
0000
0000
1100
0000
0000
kkkk
0001
0000
1, 2
1, 2
3, 4
3, 4
1, 2
CONTROL OPERATIONS
BC
BN
BNC
BNN
BNOV
BNZ
BOV
BRA
BZ
CALL
n
n
n
n
n
n
n
n
n
n, s
CLRWDT
DAW
GOTO
—
—
n
NOP
NOP
POP
PUSH
RCALL
RESET
RETFIE
—
—
—
—
n
s
Branch if Carry
Branch if Negative
Branch if Not Carry
Branch if Not Negative
Branch if Not Overflow
Branch if Not Zero
Branch if Overflow
Branch Unconditionally
Branch if Zero
Call subroutine 1st word
2nd word
Clear Watchdog Timer
Decimal Adjust WREG
Go to address 1st word
2nd word
No Operation
No Operation
Pop top of return stack (TOS)
Push top of return stack (TOS)
Relative Call
Software device Reset
Return from interrupt enable
RETLW
RETURN
SLEEP
k
s
—
Return with literal in WREG
Return from Subroutine
Go into Standby mode
Note 1:
When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value
present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is driven low by an
external device, the data will be written back with a ‘0’.
If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared if
assigned.
If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is
executed as a NOP.
Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the
first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory
locations have a valid instruction.
2:
3:
4:
 2010 Microchip Technology Inc.
1
1
2
TO, PD
C
None
None
None
None
None
None
All
GIE/GIEH,
PEIE/GIEL
kkkk None
001s None
0011 TO, PD
4
DS41303G-page 319
PIC18F2XK20/4XK20
TABLE 24-2:
PIC18FXXXX INSTRUCTION SET (CONTINUED)
16-Bit Instruction Word
Mnemonic,
Operands
Description
Cycles
MSb
LSb
Status
Affected
Notes
LITERAL OPERATIONS
ADDLW
ANDLW
IORLW
LFSR
k
k
k
f, k
MOVLB
MOVLW
MULLW
RETLW
SUBLW
XORLW
k
k
k
k
k
k
Add literal and WREG
AND literal with WREG
Inclusive OR literal with WREG
Move literal (12-bit) 2nd word
to FSR(f)
1st word
Move literal to BSR<3:0>
Move literal to WREG
Multiply literal with WREG
Return with literal in WREG
Subtract WREG from literal
Exclusive OR literal with WREG
1
1
1
2
1
1
1
2
1
1
0000
0000
0000
1110
1111
0000
0000
0000
0000
0000
0000
1111
1011
1001
1110
0000
0001
1110
1101
1100
1000
1010
kkkk
kkkk
kkkk
00ff
kkkk
0000
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
kkkk
C, DC, Z, OV, N
Z, N
Z, N
None
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
1000
1001
1010
1011
1100
1101
1110
1111
None
None
None
None
None
None
None
None
None
None
None
None
C, DC, Z, OV, N
Z, N
DATA MEMORY  PROGRAM MEMORY OPERATIONS
TBLRD*
TBLRD*+
TBLRD*TBLRD+*
TBLWT*
TBLWT*+
TBLWT*TBLWT+*
Note 1:
2:
3:
4:
Table Read
Table Read with post-increment
Table Read with post-decrement
Table Read with pre-increment
Table Write
Table Write with post-increment
Table Write with post-decrement
Table Write with pre-increment
2
2
When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value
present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is driven low by an
external device, the data will be written back with a ‘0’.
If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared if
assigned.
If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is
executed as a NOP.
Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the
first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory
locations have a valid instruction.
DS41303G-page 320
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
24.1.1
STANDARD INSTRUCTION SET
ADDLW
ADD literal to W
ADDWF
ADD W to f
Syntax:
ADDLW
Syntax:
ADDWF
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operation:
(W) + (f)  dest
Status Affected:
N, OV, C, DC, Z
k
Operands:
0  k  255
Operation:
(W) + k  W
Status Affected:
N, OV, C, DC, Z
Encoding:
0000
1111
kkkk
kkkk
Description:
The contents of W are added to the
8-bit literal ‘k’ and the result is placed in
W.
Words:
1
Cycles:
1
Encoding:
0010
Q1
Q2
Q3
Q4
Read
literal ‘k’
Process
Data
Write to W
Example:
ADDLW
=
25h
ffff
Words:
1
Cycles:
1
Before Instruction
W
ffff
Add W to register ‘f’. If ‘d’ is ‘0’, the
result is stored in W. If ‘d’ is ‘1’, the
result is stored back in register ‘f’
(default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
15h
W
= 10h
After Instruction
01da
Description:
Q Cycle Activity:
Decode
f {,d {,a}}
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
ADDWF
REG, 0, 0
Before Instruction
W
=
REG
=
After Instruction
W
REG
Note:
=
=
17h
0C2h
0D9h
0C2h
All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in
symbolic addressing. If a label is used, the instruction format then becomes: {label} instruction argument(s).
 2010 Microchip Technology Inc.
DS41303G-page 321
PIC18F2XK20/4XK20
ADDWFC
ADD W and CARRY bit to f
ANDLW
Syntax:
ADDWFC
Syntax:
ANDLW
Operands:
0  f  255
d [0,1]
a [0,1]
Operands:
0  k  255
Operation:
(W) .AND. k  W
Operation:
(W) + (f) + (C)  dest
Status Affected:
N, Z
Status Affected:
N,OV, C, DC, Z
Encoding:
0010
Description:
f {,d {,a}}
Encoding:
00da
ffff
ffff
Add W, the CARRY flag and data memory location ‘f’. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed in data memory location ‘f’.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
AND literal with W
0000
k
1011
kkkk
kkkk
Description:
The contents of W are AND’ed with the
8-bit literal ‘k’. The result is placed in W.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read literal
‘k’
Process
Data
Write to W
Example:
ANDLW
05Fh
Before Instruction
W
=
After Instruction
W
=
A3h
03h
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
ADDWFC
Before Instruction
CARRY bit =
REG
=
W
=
After Instruction
CARRY bit =
REG
=
W
=
DS41303G-page 322
REG, 0, 1
1
02h
4Dh
0
02h
50h
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
ANDWF
AND W with f
BC
Branch if Carry
Syntax:
ANDWF
Syntax:
BC
Operands:
0  f  255
d [0,1]
a [0,1]
Operands:
-128  n  127
Operation:
if CARRY bit is ‘1’
(PC) + 2 + 2n  PC
Status Affected:
None
f {,d {,a}}
Operation:
(W) .AND. (f)  dest
Status Affected:
N, Z
Encoding:
0001
Description:
Encoding:
01da
ffff
ffff
The contents of W are AND’ed with
register ‘f’. If ‘d’ is ‘0’, the result is stored
in W. If ‘d’ is ‘1’, the result is stored back
in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
ANDWF
REG, 0, 0
Before Instruction
W
=
REG
=
After Instruction
W
REG
=
=
17h
C2h
02h
C2h
 2010 Microchip Technology Inc.
n
1110
Description:
0010
nnnn
nnnn
If the CARRY bit is ‘1’, then the program
will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
1
Cycles:
1(2)
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
If No Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
HERE
Before Instruction
PC
After Instruction
If CARRY
PC
If CARRY
PC
BC
5
=
address (HERE)
=
=
=
=
1;
address (HERE + 12)
0;
address (HERE + 2)
DS41303G-page 323
PIC18F2XK20/4XK20
BCF
Bit Clear f
BN
Branch if Negative
Syntax:
BCF
Syntax:
BN
Operands:
0  f  255
0b7
a [0,1]
Operands:
-128  n  127
Operation:
if NEGATIVE bit is ‘1’
(PC) + 2 + 2n  PC
Status Affected:
None
f, b {,a}
Operation:
0  f<b>
Status Affected:
None
Encoding:
Encoding:
1001
Description:
bbba
ffff
ffff
Bit ‘b’ in register ‘f’ is cleared.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
BCF
Before Instruction
FLAG_REG =
After Instruction
FLAG_REG =
DS41303G-page 324
FLAG_REG,
7, 0
n
1110
Description:
0110
nnnn
nnnn
If the NEGATIVE bit is ‘1’, then the
program will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
1
Cycles:
1(2)
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
If No Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
C7h
47h
Example:
HERE
Before Instruction
PC
After Instruction
If NEGATIVE
PC
If NEGATIVE
PC
BN
Jump
=
address (HERE)
=
=
=
=
1;
address (Jump)
0;
address (HERE + 2)
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
BNC
Branch if Not Carry
BNN
Branch if Not Negative
Syntax:
BNC
Syntax:
BNN
Operands:
-128  n  127
Operands:
-128  n  127
Operation:
if CARRY bit is ‘0’
(PC) + 2 + 2n  PC
Operation:
if NEGATIVE bit is ‘0’
(PC) + 2 + 2n  PC
Status Affected:
None
Status Affected:
None
Encoding:
n
1110
Description:
0011
nnnn
nnnn
Encoding:
1110
If the CARRY bit is ‘0’, then the program
will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Description:
Words:
1
Words:
1
Cycles:
1(2)
Cycles:
1(2)
Q Cycle Activity:
If Jump:
n
0111
nnnn
nnnn
If the NEGATIVE bit is ‘0’, then the
program will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Decode
Read literal
‘n’
Process
Data
No
operation
If No Jump:
Example:
If No Jump:
HERE
Before Instruction
PC
After Instruction
If CARRY
PC
If CARRY
PC
BNC
Jump
=
address (HERE)
=
=
=
=
0;
address (Jump)
1;
address (HERE + 2)
 2010 Microchip Technology Inc.
Example:
HERE
Before Instruction
PC
After Instruction
If NEGATIVE
PC
If NEGATIVE
PC
BNN
Jump
=
address (HERE)
=
=
=
=
0;
address (Jump)
1;
address (HERE + 2)
DS41303G-page 325
PIC18F2XK20/4XK20
BNOV
Branch if Not Overflow
BNZ
Branch if Not Zero
Syntax:
BNOV
Syntax:
BNZ
Operands:
-128  n  127
Operands:
-128  n  127
Operation:
if OVERFLOW bit is ‘0’
(PC) + 2 + 2n  PC
Operation:
if ZERO bit is ‘0’
(PC) + 2 + 2n  PC
Status Affected:
None
Status Affected:
None
Encoding:
n
1110
Description:
0101
nnnn
nnnn
Encoding:
1110
If the OVERFLOW bit is ‘0’, then the
program will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Description:
Words:
1
Words:
1
Cycles:
1(2)
Cycles:
1(2)
Q Cycle Activity:
If Jump:
n
0001
nnnn
nnnn
If the ZERO bit is ‘0’, then the program
will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Decode
Read literal
‘n’
Process
Data
No
operation
If No Jump:
If No Jump:
Example:
HERE
Before Instruction
PC
=
After Instruction
If OVERFLOW =
PC
=
If OVERFLOW =
PC
=
DS41303G-page 326
BNOV Jump
address (HERE)
0;
address (Jump)
1;
address (HERE + 2)
Example:
HERE
Before Instruction
PC
After Instruction
If ZERO
PC
If ZERO
PC
BNZ
Jump
=
address (HERE)
=
=
=
=
0;
address (Jump)
1;
address (HERE + 2)
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
BRA
Unconditional Branch
BSF
Syntax:
BRA
Syntax:
BSF
Operands:
-1024  n  1023
Operands:
0  f  255
0b7
a [0,1]
n
Operation:
(PC) + 2 + 2n  PC
Status Affected:
None
Encoding:
1101
Description:
0nnn
nnnn
nnnn
Add the 2’s complement number ‘2n’ to
the PC. Since the PC will have incremented to fetch the next instruction, the
new address will be PC + 2 + 2n. This
instruction is a two-cycle instruction.
Words:
1
Cycles:
2
Bit Set f
Operation:
1  f<b>
Status Affected:
None
Encoding:
1000
Q1
Q2
Q3
Q4
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
Example:
bbba
ffff
ffff
Description:
Bit ‘b’ in register ‘f’ is set.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Decode
f, b {,a}
Q Cycle Activity:
HERE
Before Instruction
PC
After Instruction
PC
BRA
Jump
=
address (HERE)
=
address (Jump)
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
BSF
Before Instruction
FLAG_REG
After Instruction
FLAG_REG
 2010 Microchip Technology Inc.
FLAG_REG, 7, 1
=
0Ah
=
8Ah
DS41303G-page 327
PIC18F2XK20/4XK20
BTFSC
Bit Test File, Skip if Clear
BTFSS
Syntax:
BTFSC f, b {,a}
Syntax:
BTFSS f, b {,a}
Operands:
0  f  255
0b7
a [0,1]
Operands:
0  f  255
0b<7
a [0,1]
Operation:
skip if (f<b>) = 0
Operation:
skip if (f<b>) = 1
Status Affected:
None
Status Affected:
None
Encoding:
1011
bbba
ffff
ffff
Bit Test File, Skip if Set
Encoding:
1010
bbba
ffff
ffff
Description:
If bit ‘b’ in register ‘f’ is ‘0’, then the next
instruction is skipped. If bit ‘b’ is ‘0’, then
the next instruction fetched during the
current instruction execution is discarded
and a NOP is executed instead, making
this a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected. If
‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates in
Indexed Literal Offset Addressing
mode whenever f 95 (5Fh).
See Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Description:
If bit ‘b’ in register ‘f’ is ‘1’, then the next
instruction is skipped. If bit ‘b’ is ‘1’, then
the next instruction fetched during the
current instruction execution is discarded
and a NOP is executed instead, making
this a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected. If
‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh).
See Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Words:
1
Cycles:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Cycles:
1(2)
Note:
Q Cycle Activity:
3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
Decode
Read
register ‘f’
Process
Data
No
operation
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
If skip:
If skip:
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE
FALSE
TRUE
Before Instruction
PC
After Instruction
If FLAG<1>
PC
If FLAG<1>
PC
DS41303G-page 328
BTFSC
:
:
FLAG, 1, 0
=
address (HERE)
=
=
=
=
0;
address (TRUE)
1;
address (FALSE)
Example:
HERE
FALSE
TRUE
Before Instruction
PC
After Instruction
If FLAG<1>
PC
If FLAG<1>
PC
BTFSS
:
:
FLAG, 1, 0
=
address (HERE)
=
=
=
=
0;
address (FALSE)
1;
address (TRUE)
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
BTG
Bit Toggle f
BOV
Branch if Overflow
Syntax:
BTG f, b {,a}
Syntax:
BOV
Operands:
0  f  255
0b<7
a [0,1]
Operands:
-128  n  127
Operation:
if OVERFLOW bit is ‘1’
(PC) + 2 + 2n  PC
Status Affected:
None
Operation:
(f<b>)  f<b>
Status Affected:
None
Encoding:
0111
Description:
Words:
Cycles:
Encoding:
bbba
ffff
ffff
Bit ‘b’ in data memory location ‘f’ is
inverted.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
1110
Description:
0100
nnnn
nnnn
If the OVERFLOW bit is ‘1’, then the
program will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
1
Cycles:
1(2)
Q Cycle Activity:
If Jump:
1
Q1
Q2
Q3
Q4
1
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
n
BTG
PORTC,
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
4, 0
Before Instruction:
PORTC =
0111 0101 [75h]
After Instruction:
PORTC =
0110 0101 [65h]
 2010 Microchip Technology Inc.
If No Jump:
Example:
HERE
Before Instruction
PC
=
After Instruction
If OVERFLOW =
PC
=
If OVERFLOW =
PC
=
BOV
Jump
address (HERE)
1;
address (Jump)
0;
address (HERE + 2)
DS41303G-page 329
PIC18F2XK20/4XK20
BZ
Branch if Zero
CALL
Subroutine Call
Syntax:
BZ
Syntax:
CALL k {,s}
Operands:
-128  n  127
Operands:
Operation:
if ZERO bit is ‘1’
(PC) + 2 + 2n  PC
0  k  1048575
s [0,1]
Operation:
(PC) + 4  TOS,
k  PC<20:1>,
if s = 1
(W)  WS,
(Status)  STATUSS,
(BSR)  BSRS
Status Affected:
None
Status Affected:
n
None
Encoding:
1110
Description:
0000
nnnn
nnnn
If the ZERO bit is ‘1’, then the program
will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will
have incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
1
Cycles:
1(2)
Encoding:
1st word (k<7:0>)
2nd word(k<19:8>)
Q1
Q2
Q3
Q4
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
If No Jump:
Example:
HERE
Before Instruction
PC
After Instruction
If ZERO
PC
If ZERO
PC
DS41303G-page 330
BZ
k7kkk
kkkk
110s
k19kkk
Subroutine call of entire 2-Mbyte
memory range. First, return address
(PC + 4) is pushed onto the return
stack. If ‘s’ = 1, the W, Status and BSR
registers are also pushed into their
respective shadow registers, WS,
STATUSS and BSRS. If ‘s’ = 0, no
update occurs (default). Then, the
20-bit value ‘k’ is loaded into PC<20:1>.
CALL is a two-cycle instruction.
Words:
2
Cycles:
2
Q Cycle Activity:
Q1
Decode
Q2
Q3
Q4
Read literal PUSH PC to
‘k’<7:0>,
stack
Jump
=
address (HERE)
=
=
=
=
1;
address (Jump)
0;
address (HERE + 2)
kkkk0
kkkk8
Description:
Q Cycle Activity:
If Jump:
Decode
1110
1111
No
operation
Example:
No
operation
HERE
Before Instruction
PC
=
After Instruction
PC
=
TOS
=
WS
=
BSRS
=
STATUSS =
No
operation
CALL
Read literal
‘k’<19:8>,
Write to PC
No
operation
THERE, 1
address (HERE)
address (THERE)
address (HERE + 4)
W
BSR
Status
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
CLRF
Clear f
Syntax:
CLRF
Operands:
0  f  255
a [0,1]
Operation:
000h  f
1Z
Status Affected:
Z
Encoding:
f {,a}
0110
Description:
101a
ffff
ffff
Clears the contents of the specified
register.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
CLRF
Before Instruction
FLAG_REG
After Instruction
FLAG_REG
Clear Watchdog Timer
Syntax:
CLRWDT
Operands:
None
Operation:
000h  WDT,
000h  WDT postscaler,
1  TO,
1  PD
Status Affected:
TO, PD
Encoding:
FLAG_REG, 1
=
5Ah
=
00h
 2010 Microchip Technology Inc.
0000
0000
0000
0100
Description:
CLRWDT instruction resets the
Watchdog Timer. It also resets the
postscaler of the WDT. Status bits, TO
and PD, are set.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
Process
Data
No
operation
Example:
Q Cycle Activity:
Example:
CLRWDT
CLRWDT
Before Instruction
WDT Counter
After Instruction
WDT Counter
WDT Postscaler
TO
PD
=
?
=
=
=
=
00h
0
1
1
DS41303G-page 331
PIC18F2XK20/4XK20
COMF
Complement f
CPFSEQ
Compare f with W, skip if f = W
Syntax:
COMF
Syntax:
CPFSEQ
Operands:
0  f  255
a  [0,1]
Operation:
(f) – (W),
skip if (f) = (W)
(unsigned comparison)
Status Affected:
None
f {,d {,a}}
0  f  255
d  [0,1]
a  [0,1]
Operands:
Operation:
(f)  dest
Status Affected:
N, Z
Encoding:
0001
11da
ffff
ffff
Description:
The contents of register ‘f’ are
complemented. If ‘d’ is ‘0’, the result is
stored in W. If ‘d’ is ‘1’, the result is
stored back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Encoding:
0110
Description:
f {,a}
001a
ffff
ffff
Compares the contents of data memory
location ‘f’ to the contents of W by
performing an unsigned subtraction.
If ‘f’ = W, then the fetched instruction is
discarded and a NOP is executed
instead, making this a two-cycle
instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Example:
COMF
Before Instruction
REG
=
After Instruction
REG
=
W
=
REG, 0, 0
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
13h
If skip:
13h
ECh
Q1
Q2
Q3
No
No
No
operation
operation
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
No
No
No
operation
operation
operation
No
No
No
operation
operation
operation
Example:
DS41303G-page 332
HERE
NEQUAL
EQUAL
Q4
No
operation
Q4
No
operation
No
operation
CPFSEQ REG, 0
:
:
Before Instruction
PC Address
W
REG
After Instruction
=
=
=
HERE
?
?
If REG
PC
If REG
PC
=
=

=
W;
Address (EQUAL)
W;
Address (NEQUAL)
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
CPFSGT
Compare f with W, skip if f > W
CPFSLT
Compare f with W, skip if f < W
Syntax:
CPFSGT
Syntax:
CPFSLT
Operands:
0  f  255
a  [0,1]
Operands:
0  f  255
a  [0,1]
Operation:
(f) –W),
skip if (f) > (W)
(unsigned comparison)
Operation:
(f) –W),
skip if (f) < (W)
(unsigned comparison)
Status Affected:
None
Status Affected:
None
Encoding:
0110
Description:
Words:
f {,a}
010a
ffff
ffff
Compares the contents of data memory
location ‘f’ to the contents of the W by
performing an unsigned subtraction.
If the contents of ‘f’ are greater than the
contents of WREG, then the fetched
instruction is discarded and a NOP is
executed instead, making this a
two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Encoding:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q2
Read
register ‘f’
Q3
Process
Data
Q4
No
operation
Q1
Q2
Q3
No
No
No
operation
operation
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
No
No
No
operation
operation
operation
No
No
No
operation
operation
operation
Q4
No
operation
Example:
HERE
NGREATER
GREATER
CPFSGT REG, 0
:
:
Before Instruction
PC
W
After Instruction
=
=
Address (HERE)
?
If REG
PC
If REG
PC

=

=
W;
Address (GREATER)
W;
Address (NGREATER)
 2010 Microchip Technology Inc.
ffff
ffff
Words:
1
Cycles:
1(2)
Note:
3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
If skip:
If skip and followed by 2-word instruction:
If skip:
Q4
No
operation
No
operation
000a
Compares the contents of data memory
location ‘f’ to the contents of W by
performing an unsigned subtraction.
If the contents of ‘f’ are less than the
contents of W, then the fetched
instruction is discarded and a NOP is
executed instead, making this a
two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
Q Cycle Activity:
Q1
Decode
0110
Description:
1
Cycles:
f {,a}
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE
NLESS
LESS
CPFSLT REG, 1
:
:
Before Instruction
PC
W
After Instruction
=
=
Address (HERE)
?
If REG
PC
If REG
PC
<
=

=
W;
Address (LESS)
W;
Address (NLESS)
DS41303G-page 333
PIC18F2XK20/4XK20
DAW
Decimal Adjust W Register
DECF
Syntax:
DAW
Syntax:
DECF f {,d {,a}}
Operands:
None
Operands:
Operation:
If [W<3:0> > 9] or [DC = 1] then
(W<3:0>) + 6  W<3:0>;
else
(W<3:0>)  W<3:0>;
0  f  255
d  [0,1]
a  [0,1]
Operation:
(f) – 1  dest
Status Affected:
C, DC, N, OV, Z
If [W<7:4> + DC > 9] or [C = 1] then
(W<7:4>) + 6 + DC  W<7:4>;
else
(W<7:4>) + DC  W<7:4>
Status Affected:
Decrement f
Encoding:
0000
0000
0000
0000
DAW adjusts the eight-bit value in W,
resulting from the earlier addition of two
variables (each in packed BCD format)
and produces a correct packed BCD
result.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register W
Process
Data
Write
W
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example1:
DAW
ffff
Words:
0111
Description:
ffff
Decrement register ‘f’. If ‘d’ is ‘0’, the
result is stored in W. If ‘d’ is ‘1’, the
result is stored back in register ‘f’
(default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
C
Encoding:
01da
Description:
Before Instruction
W
=
C
=
DC
=
After Instruction
W
C
DC
Example 2:
=
=
=
A5h
0
0
05h
1
0
Example:
DECF
Before Instruction
CNT
=
Z
=
After Instruction
CNT
=
Z
=
CNT,
1, 0
01h
0
00h
1
Before Instruction
W
=
C
=
DC
=
After Instruction
W
C
DC
=
=
=
DS41303G-page 334
CEh
0
0
34h
1
0
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
DECFSZ
Decrement f, skip if 0
DCFSNZ
Syntax:
DECFSZ f {,d {,a}}
Syntax:
DCFSNZ
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operation:
(f) – 1  dest,
skip if result = 0
Operation:
(f) – 1  dest,
skip if result  0
Status Affected:
None
Status Affected:
None
Encoding:
0010
Description:
11da
ffff
ffff
The contents of register ‘f’ are
decremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is ‘0’, the next instruction,
which is already fetched, is discarded
and a NOP is executed instead, making
it a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Decrement f, skip if not 0
Encoding:
0100
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
HERE
DECFSZ
GOTO
Example:
CNT, 1, 1
LOOP
CONTINUE
Before Instruction
PC
=
After Instruction
CNT
=
If CNT
=
PC =
If CNT

PC =
Address (HERE)
CNT - 1
0;
Address (CONTINUE)
0;
Address (HERE + 2)
 2010 Microchip Technology Inc.
ffff
ffff
The contents of register ‘f’ are
decremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is not ‘0’, the next
instruction, which is already fetched, is
discarded and a NOP is executed
instead, making it a two-cycle
instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1(2)
Note:
3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
If skip:
If skip and followed by 2-word instruction:
11da
Description:
Q Cycle Activity:
Q1
f {,d {,a}}
If skip:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE
ZERO
NZERO
Before Instruction
TEMP
After Instruction
TEMP
If TEMP
PC
If TEMP
PC
DCFSNZ
:
:
TEMP, 1, 0
=
?
=
=
=

=
TEMP – 1,
0;
Address (ZERO)
0;
Address (NZERO)
DS41303G-page 335
PIC18F2XK20/4XK20
GOTO
Unconditional Branch
INCF
Syntax:
GOTO k
Syntax:
INCF
Operands:
0  k  1048575
Operands:
Operation:
k  PC<20:1>
0  f  255
d  [0,1]
a  [0,1]
Status Affected:
None
Operation:
(f) + 1  dest
Status Affected:
C, DC, N, OV, Z
Encoding:
1st word (k<7:0>)
2nd word(k<19:8>)
1110
1111
Description:
1111
k19kkk
k7kkk
kkkk
kkkk0
kkkk8
GOTO allows an unconditional branch
Increment f
Encoding:
0010
2
Cycles:
2
Q1
Q2
Q3
Q4
Read literal
‘k’<7:0>,
No
operation
Read literal
‘k’<19:8>,
Write to PC
No
operation
No
operation
No
operation
No
operation
ffff
ffff
The contents of register ‘f’ are
incremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Decode
10da
Description:
anywhere within entire
2-Mbyte memory range. The 20-bit
value ‘k’ is loaded into PC<20:1>.
GOTO is always a two-cycle
instruction.
Words:
f {,d {,a}}
Q Cycle Activity:
Example:
GOTO THERE
After Instruction
PC =
Address (THERE)
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
INCF
Before Instruction
CNT
=
Z
=
C
=
DC
=
After Instruction
CNT
=
Z
=
C
=
DC
=
DS41303G-page 336
CNT, 1, 0
FFh
0
?
?
00h
1
1
1
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
INCFSZ
Increment f, skip if 0
INFSNZ
Syntax:
INCFSZ
Syntax:
INFSNZ
0  f  255
d  [0,1]
a  [0,1]
f {,d {,a}}
Increment f, skip if not 0
f {,d {,a}}
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operands:
Operation:
(f) + 1  dest,
skip if result = 0
Operation:
(f) + 1  dest,
skip if result  0
Status Affected:
None
Status Affected:
None
Encoding:
0011
Description:
11da
ffff
ffff
The contents of register ‘f’ are
incremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is ‘0’, the next instruction,
which is already fetched, is discarded
and a NOP is executed instead, making
it a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Encoding:
0100
Description:
Words:
1
Words:
1
Cycles:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Cycles:
1(2)
Note:
Q Cycle Activity:
10da
ffff
ffff
The contents of register ‘f’ are
incremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is not ‘0’, the next
instruction, which is already fetched, is
discarded and a NOP is executed
instead, making it a two-cycle
instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Decode
Read
register ‘f’
Process
Data
Write to
destination
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
If skip:
If skip:
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE
NZERO
ZERO
Before Instruction
PC
=
After Instruction
CNT
=
If CNT
=
PC
=
If CNT

PC
=
INCFSZ
:
:
Address (HERE)
CNT + 1
0;
Address (ZERO)
0;
Address (NZERO)
 2010 Microchip Technology Inc.
CNT, 1, 0
Example:
HERE
ZERO
NZERO
Before Instruction
PC
=
After Instruction
REG
=

If REG
PC
=
If REG
=
PC
=
INFSNZ
REG, 1, 0
Address (HERE)
REG + 1
0;
Address (NZERO)
0;
Address (ZERO)
DS41303G-page 337
PIC18F2XK20/4XK20
IORLW
Inclusive OR literal with W
IORWF
Syntax:
IORLW k
Syntax:
IORWF
Operands:
0  k  255
Operands:
Operation:
(W) .OR. k  W
0  f  255
d  [0,1]
a  [0,1]
Status Affected:
N, Z
Operation:
(W) .OR. (f)  dest
Status Affected:
N, Z
Encoding:
0000
Description:
1001
kkkk
kkkk
The contents of W are ORed with the
eight-bit literal ‘k’. The result is placed in
W.
Words:
1
Cycles:
1
Inclusive OR W with f
Encoding:
0001
Q1
Q2
Q3
Q4
Read
literal ‘k’
Process
Data
Write to W
Example:
IORLW
W
=
ffff
Words:
1
Cycles:
1
35h
9Ah
BFh
ffff
Inclusive OR W with register ‘f’. If ‘d’ is
‘0’, the result is placed in W. If ‘d’ is ‘1’,
the result is placed back in register ‘f’
(default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Before Instruction
W
=
After Instruction
00da
Description:
Q Cycle Activity:
Decode
f {,d {,a}}
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
IORWF
Before Instruction
RESULT =
W
=
After Instruction
RESULT =
W
=
DS41303G-page 338
RESULT, 0, 1
13h
91h
13h
93h
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
LFSR
Load FSR
MOVF
Syntax:
LFSR f, k
Syntax:
MOVF
Operands:
0f2
0  k  4095
Operands:
Operation:
k  FSRf
0  f  255
d  [0,1]
a  [0,1]
Status Affected:
None
Operation:
f  dest
Status Affected:
N, Z
Encoding:
1110
1111
1110
0000
00ff
k7kkk
k11kkk
kkkk
Description:
The 12-bit literal ‘k’ is loaded into the
File Select Register pointed to by ‘f’.
Words:
2
Cycles:
2
Move f
Encoding:
0101
Q1
Q2
Q3
Q4
Read literal
‘k’ MSB
Process
Data
Write
literal ‘k’
MSB to
FSRfH
Decode
Read literal
‘k’ LSB
Process
Data
Write literal
‘k’ to FSRfL
Example:
After Instruction
FSR2H
FSR2L
03h
ABh
ffff
ffff
The contents of register ‘f’ are moved to
a destination dependent upon the
status of ‘d’. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
Location ‘f’ can be anywhere in the
256-byte bank.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
LFSR 2, 3ABh
=
=
00da
Description:
Q Cycle Activity:
Decode
f {,d {,a}}
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write W
Example:
MOVF
Before Instruction
REG
W
After Instruction
REG
W
 2010 Microchip Technology Inc.
REG, 0, 0
=
=
22h
FFh
=
=
22h
22h
DS41303G-page 339
PIC18F2XK20/4XK20
MOVFF
Move f to f
MOVLB
Syntax:
MOVFF fs,fd
Syntax:
MOVLW k
Operands:
0  fs  4095
0  fd  4095
Operands:
0  k  255
Operation:
k  BSR
Operation:
(fs)  fd
Status Affected:
None
Status Affected:
None
Encoding:
Encoding:
1st word (source)
2nd word (destin.)
1100
1111
Description:
ffff
ffff
ffff
ffff
ffffs
ffffd
The contents of source register ‘fs’ are
moved to destination register ‘fd’.
Location of source ‘fs’ can be anywhere
in the 4096-byte data space (000h to
FFFh) and location of destination ‘fd’
can also be anywhere from 000h to
FFFh.
Either source or destination can be W
(a useful special situation).
MOVFF is particularly useful for
transferring a data memory location to a
peripheral register (such as the transmit
buffer or an I/O port).
The MOVFF instruction cannot use the
PCL, TOSU, TOSH or TOSL as the
destination register.
Words:
2
Cycles:
2 (3)
Move literal to low nibble in BSR
0000
0001
kkkk
kkkk
Description:
The eight-bit literal ‘k’ is loaded into the
Bank Select Register (BSR). The value
of BSR<7:4> always remains ‘0’,
regardless of the value of k7:k4.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write literal
‘k’ to BSR
MOVLB
5
Example:
Before Instruction
BSR Register =
After Instruction
BSR Register =
02h
05h
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
(src)
Process
Data
No
operation
Decode
No
operation
No
operation
Write
register ‘f’
(dest)
No dummy
read
Example:
MOVFF
Before Instruction
REG1
REG2
After Instruction
REG1
REG2
DS41303G-page 340
REG1, REG2
=
=
33h
11h
=
=
33h
33h
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
MOVLW
Move literal to W
MOVWF
Syntax:
MOVLW k
Syntax:
MOVWF
Operands:
0  k  255
Operands:
Operation:
kW
0  f  255
a  [0,1]
Status Affected:
None
Operation:
(W)  f
Status Affected:
None
Encoding:
0000
1110
kkkk
kkkk
Description:
The eight-bit literal ‘k’ is loaded into W.
Words:
1
Cycles:
1
Move W to f
Encoding:
0110
Q1
Q2
Q3
Q4
Read
literal ‘k’
Process
Data
Write to W
Example:
MOVLW
=
ffff
ffff
Move data from W to register ‘f’.
Location ‘f’ can be anywhere in the
256-byte bank.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
5Ah
After Instruction
W
111a
Description:
Q Cycle Activity:
Decode
f {,a}
5Ah
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
MOVWF
REG, 0
Before Instruction
W
=
REG
=
After Instruction
W
REG
 2010 Microchip Technology Inc.
=
=
4Fh
FFh
4Fh
4Fh
DS41303G-page 341
PIC18F2XK20/4XK20
MULLW
Multiply literal with W
MULWF
Multiply W with f
Syntax:
MULLW
Syntax:
MULWF
Operands:
0  k  255
Operands:
Operation:
(W) x k  PRODH:PRODL
0  f  255
a  [0,1]
Status Affected:
None
Operation:
(W) x (f)  PRODH:PRODL
Status Affected:
None
Encoding:
0000
Description:
k
1101
kkkk
kkkk
An unsigned multiplication is carried
out between the contents of W and the
8-bit literal ‘k’. The 16-bit result is
placed in the PRODH:PRODL register
pair. PRODH contains the high byte.
W is unchanged.
None of the Status flags are affected.
Note that neither overflow nor carry is
possible in this operation. A zero result
is possible but not detected.
Words:
1
Cycles:
1
Encoding:
0000
Q1
Q2
Q3
Q4
Read
literal ‘k’
Process
Data
Write
registers
PRODH:
PRODL
Example:
MULLW
W
PRODH
PRODL
E2h
?
?
=
=
=
E2h
ADh
08h
ffff
Words:
1
Cycles:
1
0C4h
=
=
=
ffff
An unsigned multiplication is carried
out between the contents of W and the
register file location ‘f’. The 16-bit
result is stored in the PRODH:PRODL
register pair. PRODH contains the
high byte. Both W and ‘f’ are
unchanged.
None of the Status flags are affected.
Note that neither overflow nor carry is
possible in this operation. A zero
result is possible but not detected.
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used
to select the GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
f 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
Before Instruction
W
PRODH
PRODL
After Instruction
001a
Description:
Q Cycle Activity:
Decode
f {,a}
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
registers
PRODH:
PRODL
Example:
MULWF
REG, 1
Before Instruction
W
REG
PRODH
PRODL
After Instruction
W
REG
PRODH
PRODL
DS41303G-page 342
=
=
=
=
C4h
B5h
?
?
=
=
=
=
C4h
B5h
8Ah
94h
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
NEGF
Negate f
NOP
No Operation
Syntax:
NEGF
Syntax:
NOP
Operands:
0  f  255
a  [0,1]
Operands:
None
Operation:
(f)+1f
Status Affected:
N, OV, C, DC, Z
Encoding:
f {,a}
0110
Description:
1
Cycles:
1
No operation
Status Affected:
None
Encoding:
110a
ffff
0000
1111
ffff
Location ‘f’ is negated using two’s
complement. The result is placed in the
data memory location ‘f’.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Operation:
0000
xxxx
Description:
No operation.
Words:
1
Cycles:
1
0000
xxxx
0000
xxxx
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
No
operation
No
operation
Example:
None.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
NEGF
Before Instruction
REG
=
After Instruction
REG
=
REG, 1
0011 1010 [3Ah]
1100 0110 [C6h]
 2010 Microchip Technology Inc.
DS41303G-page 343
PIC18F2XK20/4XK20
POP
Pop Top of Return Stack
PUSH
Push Top of Return Stack
Syntax:
POP
Syntax:
PUSH
Operands:
None
Operands:
None
Operation:
(TOS)  bit bucket
Operation:
(PC + 2)  TOS
Status Affected:
None
Status Affected:
None
Encoding:
0000
0000
0000
0110
Description:
The TOS value is pulled off the return
stack and is discarded. The TOS value
then becomes the previous value that
was pushed onto the return stack.
This instruction is provided to enable
the user to properly manage the return
stack to incorporate a software stack.
Words:
1
Cycles:
1
Encoding:
Q2
Q3
Q4
Decode
No
operation
POP TOS
value
No
operation
POP
GOTO
NEW
Before Instruction
TOS
Stack (1 level down)
DS41303G-page 344
0000
0101
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
After Instruction
TOS
PC
0000
The PC + 2 is pushed onto the top of
the return stack. The previous TOS
value is pushed down on the stack.
This instruction allows implementing a
software stack by modifying TOS and
then pushing it onto the return stack.
Q Cycle Activity:
Example:
0000
Description:
Q1
Q2
Q3
Q4
Decode
PUSH
PC + 2 onto
return stack
No
operation
No
operation
Example:
=
=
=
=
0031A2h
014332h
014332h
NEW
PUSH
Before Instruction
TOS
PC
=
=
345Ah
0124h
After Instruction
PC
TOS
Stack (1 level down)
=
=
=
0126h
0126h
345Ah
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
RCALL
Relative Call
RESET
Reset
Syntax:
RCALL
Syntax:
RESET
Operands:
-1024  n  1023
Operands:
None
Operation:
(PC) + 2  TOS,
(PC) + 2 + 2n  PC
Operation:
Reset all registers and flags that are
affected by a MCLR Reset.
Status Affected:
None
Status Affected:
All
Encoding:
n
1101
Description:
1nnn
nnnn
nnnn
Subroutine call with a jump up to 1K
from the current location. First, return
address (PC + 2) is pushed onto the
stack. Then, add the 2’s complement
number ‘2n’ to the PC. Since the PC will
have incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is a
two-cycle instruction.
Words:
1
Cycles:
2
Encoding:
0000
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
1111
1111
Description:
This instruction provides a way to
execute a MCLR Reset by software.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Start
Reset
No
operation
No
operation
Example:
Q Cycle Activity:
0000
After Instruction
Registers =
Flags*
=
RESET
Reset Value
Reset Value
PUSH PC to
stack
No
operation
Example:
No
operation
HERE
RCALL Jump
Before Instruction
PC =
Address (HERE)
After Instruction
PC =
Address (Jump)
TOS =
Address (HERE + 2)
 2010 Microchip Technology Inc.
DS41303G-page 345
PIC18F2XK20/4XK20
RETFIE
Return from Interrupt
RETLW
Return literal to W
Syntax:
RETFIE {s}
Syntax:
RETLW k
Operands:
s  [0,1]
Operands:
0  k  255
Operation:
(TOS)  PC,
1  GIE/GIEH or PEIE/GIEL,
if s = 1
(WS)  W,
(STATUSS)  Status,
(BSRS)  BSR,
PCLATU, PCLATH are unchanged.
Operation:
k  W,
(TOS)  PC,
PCLATU, PCLATH are unchanged
Status Affected:
None
Status Affected:
0000
0000
0001
1
Cycles:
2
Q Cycle Activity:
Q2
Q3
Q4
Decode
No
operation
No
operation
POP PC
from stack
Set GIEH or
GIEL
No
operation
RETFIE
After Interrupt
PC
W
BSR
Status
GIE/GIEH, PEIE/GIEL
DS41303G-page 346
kkkk
kkkk
Words:
1
Cycles:
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
POP PC
from stack,
Write to W
No
operation
No
operation
No
operation
No
operation
Example:
Q1
Example:
1100
W is loaded with the eight-bit literal ‘k’.
The program counter is loaded from the
top of the stack (the return address).
The high address latch (PCLATH)
remains unchanged.
000s
Return from interrupt. Stack is popped
and Top-of-Stack (TOS) is loaded into
the PC. Interrupts are enabled by
setting either the high or low priority
global interrupt enable bit. If ‘s’ = 1, the
contents of the shadow registers, WS,
STATUSS and BSRS, are loaded into
their corresponding registers, W,
Status and BSR. If ‘s’ = 0, no update of
these registers occurs (default).
Words:
No
operation
0000
Description:
GIE/GIEH, PEIE/GIEL.
Encoding:
Description:
Encoding:
No
operation
No
operation
1
=
=
=
=
=
TOS
WS
BSRS
STATUSS
1
CALL TABLE ;
;
;
;
:
TABLE
ADDWF PCL ;
RETLW k0
;
RETLW k1
;
:
:
RETLW kn
;
Before Instruction
W
=
After Instruction
W
=
W contains table
offset value
W now has
table value
W = offset
Begin table
End of table
07h
value of kn
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
RETURN
Return from Subroutine
RLCF
Syntax:
RETURN {s}
Syntax:
RLCF
Operands:
s  [0,1]
Operands:
Operation:
(TOS)  PC,
if s = 1
(WS)  W,
(STATUSS)  Status,
(BSRS)  BSR,
PCLATU, PCLATH are unchanged
0  f  255
d  [0,1]
a  [0,1]
Operation:
(f<n>)  dest<n + 1>,
(f<7>)  C,
(C)  dest<0>
Status Affected:
C, N, Z
Status Affected:
None
Encoding:
0000
Rotate Left f through Carry
Encoding:
0000
0001
001s
Description:
Return from subroutine. The stack is
popped and the top of the stack (TOS)
is loaded into the program counter. If
‘s’= 1, the contents of the shadow
registers, WS, STATUSS and BSRS,
are loaded into their corresponding
registers, W, Status and BSR. If
‘s’ = 0, no update of these registers
occurs (default).
Words:
1
Cycles:
2
0011
Description:
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
Process
Data
POP PC
from stack
No
operation
No
operation
No
operation
No
operation
f {,d {,a}}
01da
ffff
ffff
The contents of register ‘f’ are rotated
one bit to the left through the CARRY
flag. If ‘d’ is ‘0’, the result is placed in
W. If ‘d’ is ‘1’, the result is stored back
in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used to
select the GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
f 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
register f
C
Words:
1
Cycles:
1
Q Cycle Activity:
Example:
RETURN
After Instruction:
PC = TOS
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
Before Instruction
REG
=
C
=
After Instruction
REG
=
W
=
C
=
 2010 Microchip Technology Inc.
RLCF
REG, 0, 0
1110 0110
0
1110 0110
1100 1100
1
DS41303G-page 347
PIC18F2XK20/4XK20
RLNCF
Rotate Left f (No Carry)
RRCF
Syntax:
RLNCF
Syntax:
RRCF
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operation:
(f<n>)  dest<n + 1>,
(f<7>)  dest<0>
Operation:
Status Affected:
N, Z
(f<n>)  dest<n – 1>,
(f<0>)  C,
(C)  dest<7>
Status Affected:
C, N, Z
Encoding:
0100
Description:
f {,d {,a}}
01da
ffff
ffff
The contents of register ‘f’ are rotated
one bit to the left. If ‘d’ is ‘0’, the result
is placed in W. If ‘d’ is ‘1’, the result is
stored back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Rotate Right f through Carry
Encoding:
0011
Description:
register f
Words:
1
Cycles:
1
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Before Instruction
REG
=
After Instruction
REG
=
DS41303G-page 348
00da
RLNCF
Words:
1
Cycles:
1
0101 0111
ffff
register f
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
RRCF
REG, 0, 0
REG, 1, 0
1010 1011
ffff
The contents of register ‘f’ are rotated
one bit to the right through the CARRY
flag. If ‘d’ is ‘0’, the result is placed in W.
If ‘d’ is ‘1’, the result is placed back in
register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
C
Q Cycle Activity:
Example:
f {,d {,a}}
Example:
Before Instruction
REG
=
C
=
After Instruction
REG
=
W
=
C
=
1110 0110
0
1110 0110
0111 0011
0
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
RRNCF
Rotate Right f (No Carry)
SETF
Syntax:
RRNCF
Syntax:
SETF
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operands:
0  f  255
a [0,1]
Operation:
FFh  f
Operation:
(f<n>)  dest<n – 1>,
(f<0>)  dest<7>
Status Affected:
None
Status Affected:
f {,d {,a}}
Encoding:
N, Z
Encoding:
0100
Description:
00da
ffff
ffff
The contents of register ‘f’ are rotated
one bit to the right. If ‘d’ is ‘0’, the result
is placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank will be
selected (default), overriding the BSR
value. If ‘a’ is ‘1’, then the bank will be
selected as per the BSR value.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
register f
Words:
1
Cycles:
1
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
RRNCF
Before Instruction
REG
=
After Instruction
REG
=
Example 2:
f {,a}
0110
100a
ffff
ffff
Description:
The contents of the specified register
are set to FFh.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
Q Cycle Activity:
Example 1:
Set f
SETF
Before Instruction
REG
After Instruction
REG
REG, 1
=
5Ah
=
FFh
REG, 1, 0
1101 0111
1110 1011
RRNCF
REG, 0, 0
Before Instruction
W
=
REG
=
After Instruction
?
1101 0111
=
=
1110 1011
1101 0111
W
REG
 2010 Microchip Technology Inc.
DS41303G-page 349
PIC18F2XK20/4XK20
SLEEP
Enter Sleep mode
SUBFWB
Syntax:
SLEEP
Syntax:
SUBFWB
Operands:
None
Operands:
Operation:
00h  WDT,
0  WDT postscaler,
1  TO,
0  PD
0 f 255
d  [0,1]
a  [0,1]
Operation:
(W) – (f) – (C) dest
Status Affected:
N, OV, C, DC, Z
Status Affected:
TO, PD
Encoding:
0000
Encoding:
0000
0000
0011
Description:
The Power-down Status bit (PD) is
cleared. The Time-out Status bit (TO)
is set. Watchdog Timer and its
postscaler are cleared.
The processor is put into Sleep mode
with the oscillator stopped.
Words:
1
Cycles:
1
0101
Q1
Q2
Q3
Q4
Decode
No
operation
Process
Data
Go to
Sleep
SLEEP
Before Instruction
TO =
?
PD =
?
After Instruction
1†
TO =
0
PD =
† If WDT causes wake-up, this bit is cleared.
DS41303G-page 350
f {,d {,a}}
01da
ffff
ffff
Description:
Subtract register ‘f’ and CARRY flag
(borrow) from W (2’s complement
method). If ‘d’ is ‘0’, the result is stored
in W. If ‘d’ is ‘1’, the result is stored in
register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used
to select the GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
f 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Example:
Subtract f from W with borrow
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
SUBFWB
REG, 1, 0
Example 1:
Before Instruction
REG
=
3
W
=
2
C
=
1
After Instruction
REG
=
FF
W
=
2
C
=
0
Z
=
0
N
=
1 ; result is negative
SUBFWB
REG, 0, 0
Example 2:
Before Instruction
REG
=
2
W
=
5
C
=
1
After Instruction
REG
=
2
W
=
3
C
=
1
Z
=
0
N
=
0 ; result is positive
SUBFWB
REG, 1, 0
Example 3:
Before Instruction
REG
=
1
W
=
2
C
=
0
After Instruction
REG
=
0
W
=
2
C
=
1
Z
=
1 ; result is zero
N
=
0
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
SUBLW
Subtract W from literal
SUBWF
Syntax:
SUBLW k
Syntax:
SUBWF
Operands:
0 k 255
Operands:
Operation:
k – (W) W
0 f 255
d  [0,1]
a  [0,1]
Status Affected:
N, OV, C, DC, Z
Operation:
(f) – (W) dest
Status Affected:
N, OV, C, DC, Z
Encoding:
0000
Description
1000
kkkk
kkkk
W is subtracted from the eight-bit
literal ‘k’. The result is placed in W.
Words:
1
Cycles:
1
Subtract W from f
Encoding:
0101
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
Example 1:
Before Instruction
W
=
C
=
After Instruction
W
=
C
=
Z
=
N
=
Example 2:
Before Instruction
W
=
C
=
After Instruction
W
=
C
=
Z
=
N
=
Example 3:
Before Instruction
W
=
C
=
After Instruction
W
=
C
=
Z
=
N
=
SUBLW
1
Cycles:
1
02h
Q Cycle Activity:
02h
?
00h
1
; result is zero
1
0
SUBLW
ffff
Words:
01h
?
SUBLW
ffff
Subtract W from register ‘f’ (2’s
complement method). If ‘d’ is ‘0’, the
result is stored in W. If ‘d’ is ‘1’, the
result is stored back in register ‘f’
(default).
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used
to select the GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
f 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
02h
01h
1
; result is positive
0
0
11da
Description:
Q Cycle Activity:
Q1
f {,d {,a}}
02h
03h
?
FFh ; (2’s complement)
0
; result is negative
0
1
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
SUBWF
REG, 1, 0
Example 1:
Before Instruction
REG
=
W
=
C
=
After Instruction
REG
=
W
=
C
=
Z
=
N
=
Example 2:
Before Instruction
REG
=
W
=
C
=
After Instruction
REG
=
W
=
C
=
Z
=
N
=
Example 3:
Before Instruction
REG
=
W
=
C
=
After Instruction
REG
=
W
=
C
=
Z
=
N
=
 2010 Microchip Technology Inc.
3
2
?
1
2
1
0
0
; result is positive
SUBWF
REG, 0, 0
2
2
?
2
0
1
1
0
SUBWF
; result is zero
REG, 1, 0
1
2
?
FFh ;(2’s complement)
2
0
; result is negative
0
1
DS41303G-page 351
PIC18F2XK20/4XK20
SUBWFB
Subtract W from f with Borrow
SWAPF
Swap f
Syntax:
SUBWFB
Syntax:
SWAPF f {,d {,a}}
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operation:
(f) – (W) – (C) dest
Operation:
Status Affected:
N, OV, C, DC, Z
(f<3:0>)  dest<7:4>,
(f<7:4>)  dest<3:0>
Status Affected:
None
Encoding:
0101
Description:
f {,d {,a}}
10da
ffff
ffff
Subtract W and the CARRY flag
(borrow) from register ‘f’ (2’s complement method). If ‘d’ is ‘0’, the result is
stored in W. If ‘d’ is ‘1’, the result is
stored back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Decode
Q2
Read
register ‘f’
Example 1:
SUBWFB
Before Instruction
REG
=
W
=
C
=
After Instruction
REG
=
W
=
C
=
Z
=
N
=
Example 2:
Q4
Write to
destination
(0001 1001)
(0000 1101)
0Ch
0Dh
1
0
0
(0000 1100)
(0000 1101)
10da
ffff
ffff
Description:
The upper and lower nibbles of register
‘f’ are exchanged. If ‘d’ is ‘0’, the result
is placed in W. If ‘d’ is ‘1’, the result is
placed in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
REG, 1, 0
19h
0Dh
1
0011
Example:
SWAPF
Before Instruction
REG
=
After Instruction
REG
=
REG, 1, 0
53h
35h
; result is positive
SUBWFB REG, 0, 0
Before Instruction
REG
=
W
=
C
=
After Instruction
REG
=
W
=
C
=
Z
=
N
=
Example 3:
1Bh
1Ah
0
(0001 1011)
(0001 1010)
1Bh
00h
1
1
0
(0001 1011)
SUBWFB
Before Instruction
REG
=
W
=
C
=
After Instruction
REG
=
W
C
Z
N
Q3
Process
Data
Encoding:
=
=
=
=
DS41303G-page 352
; result is zero
REG, 1, 0
03h
0Eh
1
(0000 0011)
(0000 1110)
F5h
(1111 0101)
; [2’s comp]
(0000 1110)
0Eh
0
0
1
; result is negative
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TBLRD
Table Read
TBLRD
Table Read (Continued)
Syntax:
TBLRD ( *; *+; *-; +*)
Example1:
TBLRD
Operands:
None
Operation:
if TBLRD *,
(Prog Mem (TBLPTR))  TABLAT;
TBLPTR – No Change;
if TBLRD *+,
(Prog Mem (TBLPTR))  TABLAT;
(TBLPTR) + 1  TBLPTR;
if TBLRD *-,
(Prog Mem (TBLPTR))  TABLAT;
(TBLPTR) – 1  TBLPTR;
if TBLRD +*,
(TBLPTR) + 1  TBLPTR;
(Prog Mem (TBLPTR))  TABLAT;
Example2:
0000
0000
0000
TBLRD
=
=
=
55h
00A356h
34h
=
=
34h
00A357h
+* ;
Before Instruction
TABLAT
TBLPTR
MEMORY (01A357h)
MEMORY (01A358h)
After Instruction
TABLAT
TBLPTR
Status Affected: None
Encoding:
*+ ;
Before Instruction
TABLAT
TBLPTR
MEMORY (00A356h)
After Instruction
TABLAT
TBLPTR
=
=
=
=
AAh
01A357h
12h
34h
=
=
34h
01A358h
10nn
nn=0 *
=1 *+
=2 *=3 +*
Description:
This instruction is used to read the contents
of Program Memory (P.M.). To address the
program memory, a pointer called Table
Pointer (TBLPTR) is used.
The TBLPTR (a 21-bit pointer) points to
each byte in the program memory. TBLPTR
has a 2-Mbyte address range.
TBLPTR[0] = 0: Least Significant Byte
of Program Memory
Word
TBLPTR[0] = 1: Most Significant Byte
of Program Memory
Word
The TBLRD instruction can modify the value
of TBLPTR as follows:
• no change
• post-increment
• post-decrement
• pre-increment
Words:
1
Cycles:
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
No
operation
No
operation
No
operation
No operation
(Read Program
Memory)
No
operation
No operation
(Write TABLAT)
 2010 Microchip Technology Inc.
DS41303G-page 353
PIC18F2XK20/4XK20
TBLWT
Table Write
TBLWT
Table Write (Continued)
Syntax:
TBLWT ( *; *+; *-; +*)
Example1:
TBLWT *+;
Operands:
None
Operation:
if TBLWT*,
(TABLAT)  Holding Register;
TBLPTR – No Change;
if TBLWT*+,
(TABLAT)  Holding Register;
(TBLPTR) + 1  TBLPTR;
if TBLWT*-,
(TABLAT)  Holding Register;
(TBLPTR) – 1  TBLPTR;
if TBLWT+*,
(TBLPTR) + 1  TBLPTR;
(TABLAT)  Holding Register;
Status Affected:
Before Instruction
TABLAT
=
55h
TBLPTR
=
00A356h
HOLDING REGISTER
(00A356h)
=
FFh
After Instructions (table write completion)
TABLAT
=
55h
TBLPTR
=
00A357h
HOLDING REGISTER
(00A356h)
=
55h
Example 2:
None
Encoding:
0000
0000
0000
11nn
nn=0 *
=1 *+
=2 *=3 +*
Description:
This instruction uses the 3 LSBs of
TBLPTR to determine which of the
8 holding registers the TABLAT is written
to. The holding registers are used to
program the contents of Program
Memory (P.M.). (Refer to Section 6.0
“Flash Program Memory” for additional
details on programming Flash memory.)
The TBLPTR (a 21-bit pointer) points to
each byte in the program memory.
TBLPTR has a 2-MByte address range.
The LSb of the TBLPTR selects which
byte of the program memory location to
access.
TBLPTR[0] = 0: Least Significant
Byte of Program
Memory Word
TBLPTR[0] = 1: Most Significant
Byte of Program
Memory Word
The TBLWT instruction can modify the
value of TBLPTR as follows:
• no change
• post-increment
• post-decrement
• pre-increment
Words:
1
Cycles:
2
TBLWT +*;
Before Instruction
TABLAT
=
34h
TBLPTR
=
01389Ah
HOLDING REGISTER
(01389Ah)
=
FFh
HOLDING REGISTER
(01389Bh)
=
FFh
After Instruction (table write completion)
TABLAT
=
34h
TBLPTR
=
01389Bh
HOLDING REGISTER
(01389Ah)
=
FFh
HOLDING REGISTER
(01389Bh)
=
34h
Q Cycle Activity:
Q1
Decode
Q2
Q3
Q4
No
No
No
operation operation operation
No
No
No
No
operation operation operation operation
(Read
(Write to
TABLAT)
Holding
Register )
DS41303G-page 354
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TSTFSZ
Test f, skip if 0
XORLW
Syntax:
TSTFSZ f {,a}
Syntax:
XORLW k
Operands:
0  f  255
a  [0,1]
Operands:
0 k 255
Operation:
(W) .XOR. k W
Operation:
skip if f = 0
Status Affected:
N, Z
Status Affected:
None
Encoding:
Encoding:
0110
Description:
Exclusive OR literal with W
011a
ffff
ffff
If ‘f’ = 0, the next instruction fetched
during the current instruction execution
is discarded and a NOP is executed,
making this a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
0000
1010
kkkk
kkkk
Description:
The contents of W are XORed with
the 8-bit literal ‘k’. The result is placed
in W.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
Example:
XORLW
0AFh
Before Instruction
W
=
After Instruction
W
=
B5h
1Ah
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
If skip:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE
NZERO
ZERO
Before Instruction
PC
After Instruction
If CNT
PC
If CNT
PC
TSTFSZ
:
:
CNT, 1
=
Address (HERE)
=
=

=
00h,
Address (ZERO)
00h,
Address (NZERO)
 2010 Microchip Technology Inc.
DS41303G-page 355
PIC18F2XK20/4XK20
XORWF
Exclusive OR W with f
Syntax:
XORWF
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operation:
(W) .XOR. (f) dest
Status Affected:
N, Z
Encoding:
0001
f {,d {,a}}
10da
ffff
ffff
Description:
Exclusive OR the contents of W with
register ‘f’. If ‘d’ is ‘0’, the result is stored
in W. If ‘d’ is ‘1’, the result is stored back
in the register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
XORWF
Before Instruction
REG
=
W
=
After Instruction
REG
=
W
=
DS41303G-page 356
REG, 1, 0
AFh
B5h
1Ah
B5h
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
24.2
Extended Instruction Set
A summary of the instructions in the extended instruction set is provided in Table 24-3. Detailed descriptions
are provided in Section 24.2.2 “Extended Instruction
Set”. The opcode field descriptions in Table 24-1 apply
to both the standard and extended PIC18 instruction
sets.
In addition to the standard 75 instructions of the PIC18
instruction set, PIC18F2XK20/4XK20 devices also
provide an optional extension to the core CPU
functionality. The added features include eight
additional instructions that augment indirect and
indexed addressing operations and the implementation
of Indexed Literal Offset Addressing mode for many of
the standard PIC18 instructions.
Note:
The additional features of the extended instruction set
are disabled by default. To enable them, users must set
the XINST Configuration bit.
The instructions in the extended set can all be
classified as literal operations, which either manipulate
the File Select Registers, or use them for indexed
addressing. Two of the instructions, ADDFSR and
SUBFSR, each have an additional special instantiation
for using FSR2. These versions (ADDULNK and
SUBULNK) allow for automatic return after execution.
24.2.1
EXTENDED INSTRUCTION SYNTAX
Most of the extended instructions use indexed
arguments, using one of the File Select Registers and
some offset to specify a source or destination register.
When an argument for an instruction serves as part of
indexed addressing, it is enclosed in square brackets
(“[ ]”). This is done to indicate that the argument is used
as an index or offset. MPASM™ Assembler will flag an
error if it determines that an index or offset value is not
bracketed.
The extended instructions are specifically implemented
to optimize re-entrant program code (that is, code that
is recursive or that uses a software stack) written in
high-level languages, particularly C. Among other
things, they allow users working in high-level
languages to perform certain operations on data
structures more efficiently. These include:
When the extended instruction set is enabled, brackets
are also used to indicate index arguments in byteoriented and bit-oriented instructions. This is in addition
to other changes in their syntax. For more details, see
Section 24.2.3.1 “Extended Instruction Syntax with
Standard PIC18 Commands”.
• dynamic allocation and deallocation of software
stack space when entering and leaving
subroutines
• function pointer invocation
• software Stack Pointer manipulation
• manipulation of variables located in a software
stack
TABLE 24-3:
The instruction set extension and the
Indexed Literal Offset Addressing mode
were designed for optimizing applications
written in C; the user may likely never use
these instructions directly in assembler.
The syntax for these commands is provided as a reference for users who may be
reviewing code that has been generated
by a compiler.
Note:
In the past, square brackets have been
used to denote optional arguments in the
PIC18 and earlier instruction sets. In this
text and going forward, optional
arguments are denoted by braces (“{ }”).
EXTENSIONS TO THE PIC18 INSTRUCTION SET
16-Bit Instruction Word
Mnemonic,
Operands
ADDFSR
ADDULNK
CALLW
MOVSF
f, k
k
MOVSS
zs, zd
PUSHL
k
SUBFSR
SUBULNK
f, k
k
zs, fd
Description
Cycles
MSb
Add literal to FSR
Add literal to FSR2 and return
Call subroutine using WREG
Move zs (source) to 1st word
fd (destination)
2nd word
Move zs (source) to 1st word
2nd word
zd (destination)
Store literal at FSR2,
decrement FSR2
Subtract literal from FSR
Subtract literal from FSR2 and
return
 2010 Microchip Technology Inc.
1
2
2
2
LSb
Status
Affected
1000
1000
0000
1011
ffff
1011
xxxx
1010
ffkk
11kk
0001
0zzz
ffff
1zzz
xzzz
kkkk
kkkk
kkkk
0100
zzzz
ffff
zzzz
zzzz
kkkk
None
None
None
None
1
1110
1110
0000
1110
1111
1110
1111
1110
1
2
1110
1110
1001
1001
ffkk
11kk
kkkk
kkkk
None
None
2
None
None
DS41303G-page 357
PIC18F2XK20/4XK20
24.2.2
EXTENDED INSTRUCTION SET
ADDFSR
Add Literal to FSR
ADDULNK
Syntax:
ADDFSR f, k
Syntax:
ADDULNK k
Operands:
0  k  63
f  [ 0, 1, 2 ]
Operands:
0  k  63
Operation:
FSR(f) + k  FSR(f)
Status Affected:
None
Encoding:
1110
Add Literal to FSR2 and Return
FSR2 + k  FSR2,
Operation:
(TOS) PC
Status Affected:
1000
ffkk
kkkk
Description:
The 6-bit literal ‘k’ is added to the
contents of the FSR specified by ‘f’.
Words:
1
Cycles:
1
None
Encoding:
1110
Q1
Q2
Q3
Q4
Read
literal ‘k’
Process
Data
Write to
FSR
Example:
ADDFSR 2, 23h
Before Instruction
FSR2
=
03FFh
After Instruction
FSR2
=
0422h
kkkk
Words:
1
Cycles:
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to
FSR
No
Operation
No
Operation
No
Operation
No
Operation
Example:
Note:
11kk
The 6-bit literal ‘k’ is added to the
contents of FSR2. A RETURN is then
executed by loading the PC with the
TOS.
The instruction takes two cycles to
execute; a NOP is performed during
the second cycle.
This may be thought of as a special
case of the ADDFSR instruction,
where f = 3 (binary ‘11’); it operates
only on FSR2.
Q Cycle Activity:
Decode
1000
Description:
ADDULNK 23h
Before Instruction
FSR2
=
PC
=
03FFh
0100h
After Instruction
FSR2
=
PC
=
0422h
(TOS)
All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in
symbolic addressing. If a label is used, the instruction syntax then becomes: {label} instruction argument(s).
DS41303G-page 358
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
CALLW
Subroutine Call Using WREG
MOVSF
Syntax:
CALLW
Syntax:
MOVSF [zs], fd
Operands:
None
Operands:
Operation:
(PC + 2)  TOS,
(W)  PCL,
(PCLATH)  PCH,
(PCLATU)  PCU
0  zs  127
0  fd  4095
Operation:
((FSR2) + zs)  fd
Status Affected:
None
Status Affected:
None
Encoding:
0000
0000
0001
0100
Description
First, the return address (PC + 2) is
pushed onto the return stack. Next, the
contents of W are written to PCL; the
existing value is discarded. Then, the
contents of PCLATH and PCLATU are
latched into PCH and PCU,
respectively. The second cycle is
executed as a NOP instruction while the
new next instruction is fetched.
Unlike CALL, there is no option to
update W, Status or BSR.
Words:
1
Cycles:
2
Move Indexed to f
Encoding:
1st word (source)
2nd word (destin.)
Q1
Q2
Q3
Q4
Read
WREG
PUSH PC to
stack
No
operation
No
operation
No
operation
No
operation
No
operation
HERE
Before Instruction
PC
=
PCLATH =
PCLATU =
W
=
After Instruction
PC
=
TOS
=
PCLATH =
PCLATU =
W
=
2
Cycles:
2
Q Cycle Activity:
Q1
Decode
address (HERE)
10h
00h
06h
 2010 Microchip Technology Inc.
zzzzs
ffffd
Words:
CALLW
001006h
address (HERE + 2)
10h
00h
06h
0zzz
ffff
The contents of the source register are
moved to destination register ‘fd’. The
actual address of the source register is
determined by adding the 7-bit literal
offset ‘zs’ in the first word to the value of
FSR2. The address of the destination
register is specified by the 12-bit literal
‘fd’ in the second word. Both addresses
can be anywhere in the 4096-byte data
space (000h to FFFh).
The MOVSF instruction cannot use the
PCL, TOSU, TOSH or TOSL as the
destination register.
If the resultant source address points to
an indirect addressing register, the
value returned will be 00h.
Decode
Example:
1011
ffff
Description:
Q Cycle Activity:
Decode
1110
1111
Q2
Q3
Determine
Determine
source addr source addr
No
operation
No
operation
No dummy
read
Example:
MOVSF
Before Instruction
FSR2
Contents
of 85h
REG2
After Instruction
FSR2
Contents
of 85h
REG2
Q4
Read
source reg
Write
register ‘f’
(dest)
[05h], REG2
=
80h
=
=
33h
11h
=
80h
=
=
33h
33h
DS41303G-page 359
PIC18F2XK20/4XK20
MOVSS
Move Indexed to Indexed
PUSHL
Syntax:
Syntax:
PUSHL k
Operands:
MOVSS [zs], [zd]
0  zs  127
0  zd  127
Operands:
0k  255
Operation:
((FSR2) + zs)  ((FSR2) + zd)
Operation:
k  (FSR2),
FSR2 – 1  FSR2
Status Affected:
None
Status Affected:
None
Encoding:
1st word (source)
2nd word (dest.)
1110
1111
Description
1011
xxxx
1zzz
xzzz
zzzzs
zzzzd
The contents of the source register are
moved to the destination register. The
addresses of the source and destination
registers are determined by adding the
7-bit literal offsets ‘zs’ or ‘zd’,
respectively, to the value of FSR2. Both
registers can be located anywhere in
the 4096-byte data memory space
(000h to FFFh).
The MOVSS instruction cannot use the
PCL, TOSU, TOSH or TOSL as the
destination register.
If the resultant source address points to
an indirect addressing register, the
value returned will be 00h. If the
resultant destination address points to
an indirect addressing register, the
instruction will execute as a NOP.
Words:
2
Cycles:
2
Store Literal at FSR2, Decrement FSR2
Encoding:
1111
1010
kkkk
kkkk
Description:
The 8-bit literal ‘k’ is written to the data
memory address specified by FSR2. FSR2
is decremented by 1 after the operation.
This instruction allows users to push values
onto a software stack.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read ‘k’
Process
data
Write to
destination
Example:
PUSHL 08h
Before Instruction
FSR2H:FSR2L
Memory (01ECh)
=
=
01ECh
00h
After Instruction
FSR2H:FSR2L
Memory (01ECh)
=
=
01EBh
08h
Q Cycle Activity:
Q1
Decode
Decode
Q2
Q3
Determine
Determine
source addr source addr
Determine
dest addr
Example:
Write
to dest reg
MOVSS [05h], [06h]
Before Instruction
FSR2
Contents
of 85h
Contents
of 86h
After Instruction
FSR2
Contents
of 85h
Contents
of 86h
DS41303G-page 360
Determine
dest addr
Q4
Read
source reg
=
80h
=
33h
=
11h
=
80h
=
33h
=
33h
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
SUBFSR
Subtract Literal from FSR
SUBULNK
Syntax:
SUBFSR f, k
Syntax:
SUBULNK k
Operands:
0  k  63
Operands:
0  k  63
f  [ 0, 1, 2 ]
Operation:
Operation:
FSR(f) – k  FSRf
Status Affected:
None
Encoding:
1110
FSR2 – k  FSR2
(TOS) PC
Status Affected: None
1001
ffkk
kkkk
Description:
The 6-bit literal ‘k’ is subtracted from
the contents of the FSR specified by
‘f’.
Words:
1
Cycles:
1
Encoding:
1110
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
SUBFSR 2, 23h
1001
11kk
kkkk
Description:
The 6-bit literal ‘k’ is subtracted from the
contents of the FSR2. A RETURN is then
executed by loading the PC with the TOS.
The instruction takes two cycles to
execute; a NOP is performed during the
second cycle.
This may be thought of as a special case of
the SUBFSR instruction, where f = 3 (binary
‘11’); it operates only on FSR2.
Words:
1
Cycles:
2
Q Cycle Activity:
Example:
Subtract Literal from FSR2 and Return
Q Cycle Activity:
Before Instruction
FSR2
=
Q1
Q2
Q3
Q4
03FFh
Decode
After Instruction
FSR2
=
Read
register ‘f’
Process
Data
Write to
destination
03DCh
No
Operation
No
Operation
No
Operation
No
Operation
Example:
 2010 Microchip Technology Inc.
SUBULNK 23h
Before Instruction
FSR2
=
PC
=
03FFh
0100h
After Instruction
FSR2
=
PC
=
03DCh
(TOS)
DS41303G-page 361
PIC18F2XK20/4XK20
24.2.3
Note:
BYTE-ORIENTED AND
BIT-ORIENTED INSTRUCTIONS IN
INDEXED LITERAL OFFSET MODE
Enabling the PIC18 instruction set
extension may cause legacy applications
to behave erratically or fail entirely.
In addition to eight new commands in the extended set,
enabling the extended instruction set also enables
Indexed Literal Offset Addressing mode (Section 5.5.1
“Indexed Addressing with Literal Offset”). This has
a significant impact on the way that many commands of
the standard PIC18 instruction set are interpreted.
When the extended set is disabled, addresses
embedded in opcodes are treated as literal memory
locations: either as a location in the Access Bank (‘a’ =
0), or in a GPR bank designated by the BSR (‘a’ = 1).
When the extended instruction set is enabled and ‘a’ =
0, however, a file register argument of 5Fh or less is
interpreted as an offset from the pointer value in FSR2
and not as a literal address. For practical purposes, this
means that all instructions that use the Access RAM bit
as an argument – that is, all byte-oriented and bitoriented instructions, or almost half of the core PIC18
instructions – may behave differently when the
extended instruction set is enabled.
When the content of FSR2 is 00h, the boundaries of the
Access RAM are essentially remapped to their original
values. This may be useful in creating backward
compatible code. If this technique is used, it may be
necessary to save the value of FSR2 and restore it
when moving back and forth between C and assembly
routines in order to preserve the Stack Pointer. Users
must also keep in mind the syntax requirements of the
extended instruction set (see Section 24.2.3.1
“Extended Instruction Syntax with Standard PIC18
Commands”).
24.2.3.1
Extended Instruction Syntax with
Standard PIC18 Commands
When the extended instruction set is enabled, the file
register argument, ‘f’, in the standard byte-oriented and
bit-oriented commands is replaced with the literal offset
value, ‘k’. As already noted, this occurs only when ‘f’ is
less than or equal to 5Fh. When an offset value is used,
it must be indicated by square brackets (“[ ]”). As with
the extended instructions, the use of brackets indicates
to the compiler that the value is to be interpreted as an
index or an offset. Omitting the brackets, or using a
value greater than 5Fh within brackets, will generate an
error in the MPASM Assembler.
If the index argument is properly bracketed for Indexed
Literal Offset Addressing, the Access RAM argument is
never specified; it will automatically be assumed to be
‘0’. This is in contrast to standard operation (extended
instruction set disabled) when ‘a’ is set on the basis of
the target address. Declaring the Access RAM bit in
this mode will also generate an error in the MPASM
Assembler.
The destination argument, ‘d’, functions as before.
In the latest versions of the MPASM™ assembler,
language support for the extended instruction set must
be explicitly invoked. This is done with either the
command line option, /y, or the PE directive in the
source listing.
24.2.4
CONSIDERATIONS WHEN
ENABLING THE EXTENDED
INSTRUCTION SET
It is important to note that the extensions to the instruction set may not be beneficial to all users. In particular,
users who are not writing code that uses a software
stack may not benefit from using the extensions to the
instruction set.
Although the Indexed Literal Offset Addressing mode
can be very useful for dynamic stack and pointer
manipulation, it can also be very annoying if a simple
arithmetic operation is carried out on the wrong
register. Users who are accustomed to the PIC18
programming must keep in mind that, when the
extended instruction set is enabled, register addresses
of 5Fh or less are used for Indexed Literal Offset
Addressing.
Additionally, the Indexed Literal Offset Addressing
mode may create issues with legacy applications
written to the PIC18 assembler. This is because
instructions in the legacy code may attempt to address
registers in the Access Bank below 5Fh. Since these
addresses are interpreted as literal offsets to FSR2
when the instruction set extension is enabled, the
application may read or write to the wrong data
addresses.
Representative examples of typical byte-oriented and
bit-oriented instructions in the Indexed Literal Offset
Addressing mode are provided on the following page to
show how execution is affected. The operand conditions shown in the examples are applicable to all
instructions of these types.
When porting an application to the PIC18F2XK20/
4XK20, it is very important to consider the type of code.
A large, re-entrant application that is written in ‘C’ and
would benefit from efficient compilation will do well
when using the instruction set extensions. Legacy
applications that heavily use the Access Bank will most
likely not benefit from using the extended instruction
set.
DS41303G-page 362
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
ADDWF
ADD W to Indexed
(Indexed Literal Offset mode)
BSF
Bit Set Indexed
(Indexed Literal Offset mode)
Syntax:
ADDWF
Syntax:
BSF [k], b
Operands:
0  k  95
d  [0,1]
Operands:
0  f  95
0b7
Operation:
(W) + ((FSR2) + k)  dest
Operation:
1  ((FSR2) + k)<b>
Status Affected:
N, OV, C, DC, Z
Status Affected:
None
Encoding:
[k] {,d}
0010
Description:
01d0
kkkk
kkkk
The contents of W are added to the
contents of the register indicated by
FSR2, offset by the value ‘k’.
If ‘d’ is ‘0’, the result is stored in W. If ‘d’
is ‘1’, the result is stored back in
register ‘f’ (default).
Encoding:
1000
bbb0
kkkk
kkkk
Description:
Bit ‘b’ of the register indicated by FSR2,
offset by the value ‘k’, is set.
Words:
1
Cycles:
1
Q Cycle Activity:
Words:
1
Q1
Q2
Q3
Q4
Cycles:
1
Decode
Read
register ‘f’
Process
Data
Write to
destination
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read ‘k’
Process
Data
Write to
destination
Example:
ADDWF
[OFST] , 0
Before Instruction
W
OFST
FSR2
Contents
of 0A2Ch
After Instruction
W
Contents
of 0A2Ch
=
=
=
17h
2Ch
0A00h
=
20h
=
37h
=
20h
Example:
BSF
Before Instruction
FLAG_OFST
FSR2
Contents
of 0A0Ah
After Instruction
Contents
of 0A0Ah
[FLAG_OFST], 7
=
=
0Ah
0A00h
=
55h
=
D5h
SETF
Set Indexed
(Indexed Literal Offset mode)
Syntax:
SETF [k]
Operands:
0  k  95
Operation:
FFh  ((FSR2) + k)
Status Affected:
None
Encoding:
0110
1000
kkkk
kkkk
Description:
The contents of the register indicated by
FSR2, offset by ‘k’, are set to FFh.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read ‘k’
Process
Data
Write
register
Example:
SETF
Before Instruction
OFST
FSR2
Contents
of 0A2Ch
After Instruction
Contents
of 0A2Ch
 2010 Microchip Technology Inc.
[OFST]
=
=
2Ch
0A00h
=
00h
=
FFh
DS41303G-page 363
PIC18F2XK20/4XK20
24.2.5
SPECIAL CONSIDERATIONS WITH
MICROCHIP MPLAB® IDE TOOLS
The latest versions of Microchip’s software tools have
been designed to fully support the extended instruction
set of the PIC18F2XK20/4XK20 family of devices. This
includes the MPLAB C18 C compiler, MPASM
assembly
language
and
MPLAB
Integrated
Development Environment (IDE).
When selecting a target device for software
development, MPLAB IDE will automatically set default
Configuration bits for that device. The default setting for
the XINST Configuration bit is ‘0’, disabling the
extended instruction set and Indexed Literal Offset
Addressing mode. For proper execution of applications
developed to take advantage of the extended
instruction set, XINST must be set during
programming.
To develop software for the extended instruction set,
the user must enable support for the instructions and
the Indexed Addressing mode in their language tool(s).
Depending on the environment being used, this may be
done in several ways:
• A menu option, or dialog box within the
environment, that allows the user to configure the
language tool and its settings for the project
• A command line option
• A directive in the source code
These options vary between different compilers,
assemblers and development environments. Users are
encouraged to review the documentation accompanying
their development systems for the appropriate
information.
DS41303G-page 364
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
25.0
DEVELOPMENT SUPPORT
The PIC® microcontrollers and dsPIC® digital signal
controllers are supported with a full range of software
and hardware development tools:
• Integrated Development Environment
- MPLAB® IDE Software
• Compilers/Assemblers/Linkers
- MPLAB C Compiler for Various Device
Families
- HI-TECH C for Various Device Families
- MPASMTM Assembler
- MPLINKTM Object Linker/
MPLIBTM Object Librarian
- MPLAB Assembler/Linker/Librarian for
Various Device Families
• Simulators
- MPLAB SIM Software Simulator
• Emulators
- MPLAB REAL ICE™ In-Circuit Emulator
• In-Circuit Debuggers
- MPLAB ICD 3
- PICkit™ 3 Debug Express
• Device Programmers
- PICkit™ 2 Programmer
- MPLAB PM3 Device Programmer
• Low-Cost Demonstration/Development Boards,
Evaluation Kits, and Starter Kits
25.1
MPLAB Integrated Development
Environment Software
The MPLAB IDE software brings an ease of software
development previously unseen in the 8/16/32-bit
microcontroller market. The MPLAB IDE is a Windows®
operating system-based application that contains:
• A single graphical interface to all debugging tools
- Simulator
- Programmer (sold separately)
- In-Circuit Emulator (sold separately)
- In-Circuit Debugger (sold separately)
• A full-featured editor with color-coded context
• A multiple project manager
• Customizable data windows with direct edit of
contents
• High-level source code debugging
• Mouse over variable inspection
• Drag and drop variables from source to watch
windows
• Extensive on-line help
• Integration of select third party tools, such as
IAR C Compilers
The MPLAB IDE allows you to:
• Edit your source files (either C or assembly)
• One-touch compile or assemble, and download to
emulator and simulator tools (automatically
updates all project information)
• Debug using:
- Source files (C or assembly)
- Mixed C and assembly
- Machine code
MPLAB IDE supports multiple debugging tools in a
single development paradigm, from the cost-effective
simulators, through low-cost in-circuit debuggers, to
full-featured emulators. This eliminates the learning
curve when upgrading to tools with increased flexibility
and power.
 2010 Microchip Technology Inc.
DS41303G-page 365
PIC18F2XK20/4XK20
25.2
MPLAB C Compilers for Various
Device Families
The MPLAB C Compiler code development systems
are complete ANSI C compilers for Microchip’s PIC18,
PIC24 and PIC32 families of microcontrollers and the
dsPIC30 and dsPIC33 families of digital signal controllers. These compilers provide powerful integration
capabilities, superior code optimization and ease of
use.
For easy source level debugging, the compilers provide
symbol information that is optimized to the MPLAB IDE
debugger.
25.3
HI-TECH C for Various Device
Families
The HI-TECH C Compiler code development systems
are complete ANSI C compilers for Microchip’s PIC
family of microcontrollers and the dsPIC family of digital
signal controllers. These compilers provide powerful
integration capabilities, omniscient code generation
and ease of use.
For easy source level debugging, the compilers provide
symbol information that is optimized to the MPLAB IDE
debugger.
The compilers include a macro assembler, linker, preprocessor, and one-step driver, and can run on multiple
platforms.
25.4
MPASM Assembler
The MPASM Assembler is a full-featured, universal
macro assembler for PIC10/12/16/18 MCUs.
The MPASM Assembler generates relocatable object
files for the MPLINK Object Linker, Intel® standard HEX
files, MAP files to detail memory usage and symbol
reference, absolute LST files that contain source lines
and generated machine code and COFF files for
debugging.
The MPASM Assembler features include:
25.5
MPLINK Object Linker/
MPLIB Object Librarian
The MPLINK Object Linker combines relocatable
objects created by the MPASM Assembler and the
MPLAB C18 C Compiler. It can link relocatable objects
from precompiled libraries, using directives from a
linker script.
The MPLIB Object Librarian manages the creation and
modification of library files of precompiled code. When
a routine from a library is called from a source file, only
the modules that contain that routine will be linked in
with the application. This allows large libraries to be
used efficiently in many different applications.
The object linker/library features include:
• Efficient linking of single libraries instead of many
smaller files
• Enhanced code maintainability by grouping
related modules together
• Flexible creation of libraries with easy module
listing, replacement, deletion and extraction
25.6
MPLAB Assembler, Linker and
Librarian for Various Device
Families
MPLAB Assembler produces relocatable machine
code from symbolic assembly language for PIC24,
PIC32 and dsPIC devices. MPLAB C Compiler uses
the assembler to produce its object file. The assembler
generates relocatable object files that can then be
archived or linked with other relocatable object files and
archives to create an executable file. Notable features
of the assembler include:
•
•
•
•
•
•
Support for the entire device instruction set
Support for fixed-point and floating-point data
Command line interface
Rich directive set
Flexible macro language
MPLAB IDE compatibility
• Integration into MPLAB IDE projects
• User-defined macros to streamline
assembly code
• Conditional assembly for multi-purpose
source files
• Directives that allow complete control over the
assembly process
DS41303G-page 366
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
25.7
MPLAB SIM Software Simulator
The MPLAB SIM Software Simulator allows code
development in a PC-hosted environment by simulating the PIC MCUs and dsPIC® DSCs on an instruction
level. On any given instruction, the data areas can be
examined or modified and stimuli can be applied from
a comprehensive stimulus controller. Registers can be
logged to files for further run-time analysis. The trace
buffer and logic analyzer display extend the power of
the simulator to record and track program execution,
actions on I/O, most peripherals and internal registers.
The MPLAB SIM Software Simulator fully supports
symbolic debugging using the MPLAB C Compilers,
and the MPASM and MPLAB Assemblers. The software simulator offers the flexibility to develop and
debug code outside of the hardware laboratory environment, making it an excellent, economical software
development tool.
25.8
MPLAB REAL ICE In-Circuit
Emulator System
MPLAB REAL ICE In-Circuit Emulator System is
Microchip’s next generation high-speed emulator for
Microchip Flash DSC and MCU devices. It debugs and
programs PIC® Flash MCUs and dsPIC® Flash DSCs
with the easy-to-use, powerful graphical user interface of
the MPLAB Integrated Development Environment (IDE),
included with each kit.
The emulator is connected to the design engineer’s PC
using a high-speed USB 2.0 interface and is connected
to the target with either a connector compatible with incircuit debugger systems (RJ11) or with the new highspeed, noise tolerant, Low-Voltage Differential Signal
(LVDS) interconnection (CAT5).
The emulator is field upgradable through future firmware
downloads in MPLAB IDE. In upcoming releases of
MPLAB IDE, new devices will be supported, and new
features will be added. MPLAB REAL ICE offers significant advantages over competitive emulators including
low-cost, full-speed emulation, run-time variable
watches, trace analysis, complex breakpoints, a ruggedized probe interface and long (up to three meters) interconnection cables.
 2010 Microchip Technology Inc.
25.9
MPLAB ICD 3 In-Circuit Debugger
System
MPLAB ICD 3 In-Circuit Debugger System is Microchip's most cost effective high-speed hardware
debugger/programmer for Microchip Flash Digital Signal Controller (DSC) and microcontroller (MCU)
devices. It debugs and programs PIC® Flash microcontrollers and dsPIC® DSCs with the powerful, yet easyto-use graphical user interface of MPLAB Integrated
Development Environment (IDE).
The MPLAB ICD 3 In-Circuit Debugger probe is connected to the design engineer's PC using a high-speed
USB 2.0 interface and is connected to the target with a
connector compatible with the MPLAB ICD 2 or MPLAB
REAL ICE systems (RJ-11). MPLAB ICD 3 supports all
MPLAB ICD 2 headers.
25.10 PICkit 3 In-Circuit Debugger/
Programmer and
PICkit 3 Debug Express
The MPLAB PICkit 3 allows debugging and programming of PIC® and dsPIC® Flash microcontrollers at a
most affordable price point using the powerful graphical
user interface of the MPLAB Integrated Development
Environment (IDE). The MPLAB PICkit 3 is connected
to the design engineer's PC using a full speed USB
interface and can be connected to the target via an
Microchip debug (RJ-11) connector (compatible with
MPLAB ICD 3 and MPLAB REAL ICE). The connector
uses two device I/O pins and the reset line to implement in-circuit debugging and In-Circuit Serial Programming™.
The PICkit 3 Debug Express include the PICkit 3, demo
board and microcontroller, hookup cables and CDROM
with user’s guide, lessons, tutorial, compiler and
MPLAB IDE software.
DS41303G-page 367
PIC18F2XK20/4XK20
25.11 PICkit 2 Development
Programmer/Debugger and
PICkit 2 Debug Express
25.13 Demonstration/Development
Boards, Evaluation Kits, and
Starter Kits
The PICkit™ 2 Development Programmer/Debugger is
a low-cost development tool with an easy to use interface for programming and debugging Microchip’s Flash
families of microcontrollers. The full featured
Windows® programming interface supports baseline
(PIC10F,
PIC12F5xx,
PIC16F5xx),
midrange
(PIC12F6xx, PIC16F), PIC18F, PIC24, dsPIC30,
dsPIC33, and PIC32 families of 8-bit, 16-bit, and 32-bit
microcontrollers, and many Microchip Serial EEPROM
products. With Microchip’s powerful MPLAB Integrated
Development Environment (IDE) the PICkit™ 2
enables in-circuit debugging on most PIC® microcontrollers. In-Circuit-Debugging runs, halts and single
steps the program while the PIC microcontroller is
embedded in the application. When halted at a breakpoint, the file registers can be examined and modified.
A wide variety of demonstration, development and
evaluation boards for various PIC MCUs and dsPIC
DSCs allows quick application development on fully functional systems. Most boards include prototyping areas for
adding custom circuitry and provide application firmware
and source code for examination and modification.
The PICkit 2 Debug Express include the PICkit 2, demo
board and microcontroller, hookup cables and CDROM
with user’s guide, lessons, tutorial, compiler and
MPLAB IDE software.
25.12 MPLAB PM3 Device Programmer
The MPLAB PM3 Device Programmer is a universal,
CE compliant device programmer with programmable
voltage verification at VDDMIN and VDDMAX for
maximum reliability. It features a large LCD display
(128 x 64) for menus and error messages and a modular, detachable socket assembly to support various
package types. The ICSP™ cable assembly is included
as a standard item. In Stand-Alone mode, the MPLAB
PM3 Device Programmer can read, verify and program
PIC devices without a PC connection. It can also set
code protection in this mode. The MPLAB PM3
connects to the host PC via an RS-232 or USB cable.
The MPLAB PM3 has high-speed communications and
optimized algorithms for quick programming of large
memory devices and incorporates an MMC card for file
storage and data applications.
DS41303G-page 368
The boards support a variety of features, including LEDs,
temperature sensors, switches, speakers, RS-232
interfaces, LCD displays, potentiometers and additional
EEPROM memory.
The demonstration and development boards can be
used in teaching environments, for prototyping custom
circuits and for learning about various microcontroller
applications.
In addition to the PICDEM™ and dsPICDEM™ demonstration/development board series of circuits, Microchip
has a line of evaluation kits and demonstration software
for analog filter design, KEELOQ® security ICs, CAN,
IrDA®, PowerSmart battery management, SEEVAL®
evaluation system, Sigma-Delta ADC, flow rate
sensing, plus many more.
Also available are starter kits that contain everything
needed to experience the specified device. This usually
includes a single application and debug capability, all
on one board.
Check the Microchip web page (www.microchip.com)
for the complete list of demonstration, development
and evaluation kits.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.0
ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings (†)
Ambient temperature under bias.............................................................................................................-40°C to +125°C
Storage temperature .............................................................................................................................. -65°C to +150°C
Voltage on any pin with respect to VSS (except VDD, and MCLR) .................................................. -0.3V to (VDD + 0.3V)
Voltage on VDD with respect to VSS ......................................................................................................... -0.3V to +4.5V
Voltage on MCLR with respect to VSS (Note 2) ............................................................................................0V to +11.0V
Total power dissipation (Note 1) ...............................................................................................................................1.0W
Maximum current out of VSS pin (-40°C to +85°C) .............................................................................................. 300 mA
Maximum current out of VSS pin (+85°C to +125°C)............................................................................................ 125 mA
Maximum current into VDD pin (-40°C to +85°C) ................................................................................................ 200 mA
Maximum current into VDD pin (+85°C to +125°C) ................................................................................................85 mA
Input clamp current, IIK (VI < 0 or VI > VDD) 20 mA
Output clamp current, IOK (VO < 0 or VO > VDD)  20 mA
Maximum output current sunk by any I/O pin..........................................................................................................25 mA
Maximum output current sourced by any I/O pin ....................................................................................................25 mA
Maximum current sunk byall ports (-40°C to +85°C)........................................................................................... 200 mA
Maximum current sunk byall ports (+85°C to +125°C)......................................................................................... 110 mA
Maximum current sourced by all ports (-40°C to +85°C) ......................................................................................185 mA
Maximum current sourced by all ports (+85°C to +125°C) .....................................................................................70 mA
Note 1: Power dissipation is calculated as follows:
Pdis = VDD x {IDD –  IOH} +  {(VDD – VOH) x IOH} + (VOL x IOL)
2: Voltage spikes below VSS at the MCLR/VPP/RE3 pin, inducing currents greater than 80 mA, may cause
latch-up. Thus, a series resistor of 50-100 should be used when applying a “low” level to the
MCLR/VPP/RE3 pin, rather than pulling this pin directly to VSS.
† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
 2010 Microchip Technology Inc.
DS41303G-page 369
PIC18F2XK20/4XK20
FIGURE 26-1:
PIC18F2XK20/4XK20 VOLTAGE-FREQUENCY GRAPH (EXTENDED)
3.5V
3.0V
Voltage
2.7V
2.0V
1.8V
10
16
20
30 32
40
48 50
60
64
Frequency (MHz)
Note:
Maximum Frequency 16 MHz, 1.8V to 2.0V, -40°C to +125°C
Maximum Frequency 20 MHz, 2.0V to 3.0V, -40°C to +125°C
Maximum Frequency 48 MHz, 3.0V to 3.6V, -40°C to +125°C
FIGURE 26-2:
PIC18F2XK20/4XK20 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
3.5V
3.0V
Voltage
2.7V
2.0V
1.8V
10
16
20
30 32
40
50
60
64
Frequency (MHz)
Note:
DS41303G-page 370
Maximum Frequency 16 MHz, 1.8V to 2.0V, -40°C to +85°C
Maximum Frequency 20 MHz, 2.0V to 3.0V, -40°C to +85°C
Maximum Frequency 64 MHz, 3.0V to 3.6V, -40°C to +85°C
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.1
DC Characteristics: Supply Voltage, PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
Symbol
No.
Characteristic
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Min
Typ
Max
Units
D001
VDD
Supply Voltage
1.8
—
3.6
V
D002
VDR
RAM Data Retention
Voltage(1)
1.5
—
—
V
D003
VPOR
VDD Start Voltage
to ensure internal
Power-on Reset signal
—
—
0.7
V
D004
SVDD
VDD Rise Rate
to ensure internal
Power-on Reset signal
0.05
—
—
D005
VBOR
Brown-out Reset Voltage
Note 1:
See section on Power-on Reset for details
V/ms See section on Power-on Reset for details
BORV<1:0> = 11(2)
1.72
1.82
1.95
V
BORV<1:0> = 10
2.15
2.27
2.40
V
BORV<1:0> = 01
2.65
2.75
2.90
V
BORV<1:0> = 00(3)
2.98
3.08
3.25
V
This is the limit to which VDD can be lowered in Sleep mode, or during a device Reset, without losing RAM
data.
With BOR enabled, operation is supported until a BOR occurs. This is valid although VDD may be below the
minimum rated supply voltage.
With BOR enabled, full-speed operation (FOSC = 64 MHZ) is supported until a BOR occurs. This is valid
although VDD may be below the minimum voltage for this frequency.
2:
3:
26.2
Conditions
DC Characteristics: Power-Down Current, PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
No.
D006
Device Characteristics
Typ
Max Units
Power-down Current (IPD)(1)
0.05
1.0
A
-40°C
0.05
1.0
A
+25°C
0.6
3.0
A
+85°C
D007
Note 1:
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Conditions
4
20
A
+125°C
0.1
1.0
A
-40°C
0.1
1.0
A
+25°C
0.7
3.0
A
+85°C
5
20
A
+125°C
VDD = 1.8V, (Sleep mode)
VDD = 3.0V, (Sleep mode)
The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is
measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and
all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
 2010 Microchip Technology Inc.
DS41303G-page 371
PIC18F2XK20/4XK20
26.3
DC Characteristics: RC Run Supply Current, PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
No.
Device Characteristics
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Typ
Max Units
Conditions
5.5
9
A
-40°C
6.0
10
A
+25°C
6.5
14
A
+85°C
9.0
30
A
+125°C
10.0
15
A
-40°C
10.5
16
A
+25°C
11.0
20
A
+85°C
14.0
40
A
+125°C
D009
0.40
0.50
mA
-40°C TO +125°C
VDD = 1.8V
D009A
0.60
0.80
mA
-40°C TO +125°C
VDD = 3.0V
D010
2.2
3.0
mA
-40°C TO +125°C
VDD = 1.8V
D010A
3.8
4.4
mA
-40°C TO +125°C
VDD = 3.0V
Supply Current (IDD)(1, 2)
D008
D008A
Note 1:
2:
VDD = 1.8V
FOSC = 31 kHz
(RC_RUN mode,
LFINTOSC source)
VDD = 3.0V
FOSC = 1 MHz
(RC_RUN mode,
HF-INTOSC source)
FOSC = 16 MHz
(RC_RUN mode,
HF-INTOSC source)
The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as
I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and
temperature, also have an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
All I/O pins set as outputs driven to Vss;
MCLR = VDD;
OSC1 = external square wave, from rail-to-rail (PRI_RUN and PRI_IDLE only).
DS41303G-page 372
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.4
DC Characteristics: RC Idle Supply Current, PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
No.
D011
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Device Characteristics
Typ
Max Units
Conditions
Supply Current (IDD)(1, 2)
2.0
5
A
-40°C
2.0
5
A
+25°C
2.5
9
A
+85°C
5.0
25
A
+125°C
VDD = 1.8V
FOSC = 31 kHz
(RC_IDLE mode,
LFINTOSC source)
3.5
8
A
-40°C
3.5
8
A
+25°C
4.0
12
A
+85°C
7.0
30
A
+125°C
D012
0.30
0.40
mA
-40°C to +125°C
VDD = 1.8V
D012A
0.40
0.60
mA
-40°C to +125°C
VDD = 3.0V
D013
1.0
1.2
mA
-40°C to +125°C
VDD = 1.8V
D013A
1.6
2.0
mA
-40°C to +125°C
VDD = 3.0V
D011A
Note 1:
2:
VDD = 3.0V
FOSC = 1 MHz
(RC_IDLE mode,
HF-INTOSC source)
FOSC = 16 MHz
(RC_IDLE mode,
HF-INTOSC source)
The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as
I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and
temperature, also have an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
All I/O pins set as outputs driven to Vss;
MCLR = VDD;
OSC1 = external square wave, from rail-to-rail (PRI_RUN and PRI_IDLE only).
 2010 Microchip Technology Inc.
DS41303G-page 373
PIC18F2XK20/4XK20
26.5
DC Characteristics: Primary Run Supply Current, PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
No.
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Device Characteristics
Typ
Max Units
Supply Current (IDD)(1, 2)
0.25
0.45
mA
-40°C to +125°C
VDD = 1.8V
D014A
0.50
0.75
mA
-40°C to +125°C
VDD = 3.0V
D015
2.7
3.2
mA
-40°C to +125°C
VDD = 2V
D015A
4.3
5.0
mA
-40°C to +125°C
VDD = 3.0V
12.2
14.0
mA
-40°C to +85°C
VDD = 3.0V
D017
2.1
2.9
mA
-40°C to +125°C
VDD = 1.8V
D017A
4.2
5.0
mA
-40°C to +125°C
VDD = 3.0V
12.2
15.0
mA
-40°C to +85°C
VDD = 3.0V
D014
Conditions
D016
D018
Note 1:
2:
26.6
FOSC = 1 MHz
(PRI_RUN,
EC oscillator)
FOSC = 20 MHz
(PRI_RUN,
EC oscillator)
FOSC = 64 MHz
(PRI_RUN,
EC oscillator)
FOSC = 4 MHz
16 MHz Internal
(PRI_RUN HS+PLL)
FOSC = 16 MHz
64 MHz Internal
(PRI_RUN HS+PLL)
The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as
I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and
temperature, also have an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
All I/O pins set as outputs driven to Vss;
MCLR = VDD;
OSC1 = external square wave, from rail-to-rail (PRI_RUN and PRI_IDLE only).
DC Characteristics: Primary Idle Supply Current, PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
No.
D019
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Device Characteristics
Typ
Max Units
Supply Current (IDD)(1, 2)
0.05
0.07
mA
-40°C to +125°C
VDD = 1.8V
0.09
0.15
mA
-40°C to +125°C
VDD = 3.0V
1.2
1.6
mA
-40°C to +125°C
VDD = 2.0V
1.8
2.5
mA
-40°C to +125°C
VDD = 3.0V
5.6
7.0
mA
-40°C to +85°C
VDD = 3.0V
D019A
D020
D020A
Conditions
D021
Note 1:
2:
FOSC = 1 MHz
(PRI_IDLE mode,
EC oscillator)
FOSC = 20 MHz
(PRI_IDLEmode,
EC oscillator)
FOSC = 64 MHz
(PRI_IDLEmode,
EC oscillator)
The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as
I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and
temperature, also have an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
All I/O pins set as outputs driven to Vss;
MCLR = VDD;
OSC1 = external square wave, from rail-to-rail (PRI_RUN and PRI_IDLE only).
DS41303G-page 374
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.7
DC Characteristics: Secondary Oscillator Supply Current, PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
No.
D022
Device Characteristics
Typ
Supply Current (IDD)(1, 2)
5.5
9
A
-40°C
5.5
10
A
+25°C
6.5
14
A
+85°C
10.0
15
A
-40°C
10.0
16
A
+25°C
11.0
20
A
+85°C
2.0
5
A
-40°C
2.0
5
A
+25°C
2.5
9
A
+85°C
3.5
8
A
-40°C
3.5
8
A
+25°C
4.0
12
A
+85°C
D022A
D023
D023A
Note 1:
2:
3:
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Max Units
Conditions
VDD = 1.8V
FOSC = 32 kHz(3)
(SEC_RUN mode,
Timer1 as clock)
VDD = 3.0V
VDD = 1.8V
FOSC = 32 kHz(3)
(SEC_IDLE mode,
Timer1 as clock)
VDD = 3.0V
The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as
I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and
temperature, also have an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
All I/O pins set as outputs driven to Vss;
MCLR = VDD;
OSC1 = external square wave, from rail-to-rail (PRI_RUN and PRI_IDLE only).
Low-Power mode on T1 osc. Low-Power mode is limited to 85°C.
 2010 Microchip Technology Inc.
DS41303G-page 375
PIC18F2XK20/4XK20
26.8
DC Characteristics: Peripheral Supply Current, PIC18F2XK20/4XK20
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
PIC18F2XK20/4XK20
Param
No.
Device Characteristics
Typ
Max
Unit
s
Conditions
Module Differential Currents
D024
(IWDT)
Watchdog Timer
D024A
(IBOR)
Reset(2)
Brown-out
D024B
(IHLVD)
High/Low-Voltage Detect(2)
D025
(IOSCB)
LP
Timer1 Oscillator
D025A
(IOSCB)
HP
Timer1 Oscillator
A/D Converter(4)
D026
(IAD)
IFRC
Comparators
D027
(ICOMP)
CVREF
D028
(ICVREF)
Note 1:
2:
3:
4:
0.7
2.0
A
-40°C to +125°C
VDD = 1.8V
1.1
3.0
A
-40°C to +125°C
VDD = 3.0V
21
50
A
-40C to +125C
VDD = 2.0V
25
60
A
-40C to +125C
VDD = 3.3V
0
—
A
-40C to +125C
VDD = 3.3V
13
30
A
-40C to +125C
VDD = 1.8-3.0V
0.5
2.0
A
-40C
0.5
2.0
A
+25C
0.7
2.0
A
+85C
0.7
3.0
A
-40C
0.7
3.0
A
+25C
0.9
3.0
A
+85C
11
30
A
-40C
13
33
A
+25C
15
35
A
+85C
14
33
A
-40C
17
37
A
+25C
Sleep mode,
BOREN<1:0> = 10
VDD = 1.8V
32 kHz on Timer1(1)
VDD = 3.0V
32 kHz on Timer1(1)
VDD = 1.8V
32 kHz on Timer1(3)
VDD = 3.0V
32 kHz on Timer1(3)
19
40
A
+85C
200
290
A
-40C to +125C
VDD = 1.8V
260
425
A
-40C to +125C
VDD = 3.0V
2
5
A
-40C to +125C
VDD = 1.8V
11
18
A
-40C to +125C
VDD = 3.0V
A/D on, not converting
Adder for FRC
5
15
A
-40C to +125C
VDD = 1.8-3.0V
LP mode
40
90
A
-40C to +125C
VDD = 1.8-3.0V
HP mode
18
40
A
-40C to +125C
VDD = 1.8V
32
60
A
-40C to +125C
VDD = 3.0V
Low-Power mode on T1 osc. Low-Power mode is limited to 85°C.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
High-Power mode in T1 osc.
A/D converter differential currents apply only in RUN mode. In SLEEP or IDLE mode both the ADC and the FRC
turn off as soon as conversion (if any) is complete.
DS41303G-page 376
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.9
DC Characteristics: Input/Output Characteristics, PIC18F2XK20/4XK20
DC CHARACTERISTICS
Param
Symbol
No.
VIL
Characteristic
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA  +125°C
Min
Typ†
Max
Units
with TTL buffer
VSS
—
0.15 VDD
V
with Schmitt Trigger
Conditions
Input Low Voltage
I/O ports:
D030
D031
VSS
—
0.2 VDD
V
D032
MCLR
VSS
—
0.2 VDD
V
D033
OSC1
VSS
—
0.3 VDD
V
HS, HSPLL modes
D033A
D033B
D034
OSC1
OSC1
T13CKI
VSS
VSS
VSS
—
—
—
0.2 VDD
0.3 VDD
0.3 VDD
V
V
V
RC, EC modes(1)
XT, LP modes
0.25 VDD + 0.8V
—
VDD
V
0.8 VDD
0.9 VDD
—
—
VDD
VDD
V
V
2.4V < VDD < 3.6V
VDD < 2.4V
MCLR
0.8 VDD
0.9 VDD
—
—
VDD
VDD
V
V
2.4V < VDD < 3.6V
VDD < 2.4V
D043
OSC1
0.7 VDD
—
VDD
V
HS, HSPLL modes
D043A
D043B
D043C
D044
OSC1
OSC1
OSC1
T13CKI
0.8 VDD
0.9 VDD
1.6
1.6
—
—
—
—
VDD
VDD
VDD
VDD
V
V
V
V
EC mode
RC mode(1)
XT, LP modes
VIH
Input High Voltage
I/O ports:
D040
with TTL buffer
D041
VIH
D042
VIH
IIL
D060
with Schmitt Trigger:
VSS VPIN VDD,
Pin at
high-impedance
Input Leakage I/O and
MCLR(2,3)
I/O ports
—
—
—
—
5
10
30
100
50
100
200
1000
nA
nA
nA
nA
+25°C
+60°C
+85°C
+125°C
—
—
—
—
10
35
200
400
100
250
750
2000
nA
nA
nA
nA
+25°C
+60°C
+85°C
+125°C
—
—
—
—
10
25
70
300
80
200
500
1500
nA
nA
nA
nA
+25°C
+60°C
+85°C
+125°C
Input Leakage RA2
D061
IIL
D062
IIL
Input Leakage RA3
Note 1:
2:
3:
4:
In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended that
the PIC® device be driven with an external clock while in RC mode.
The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified
levels represent normal operating conditions. Higher leakage current may be measured at different input
voltages.
Negative current is defined as current sourced by the pin.
Parameter is characterized but not tested.
 2010 Microchip Technology Inc.
DS41303G-page 377
PIC18F2XK20/4XK20
26.9
DC Characteristics: Input/Output Characteristics, PIC18F2XK20/4XK20 (Continued)
DC CHARACTERISTICS
Param
Symbol
No.
D070
Note 1:
2:
3:
4:
Characteristic
IPU
Weak Pull-up Current
IPURB
PORTB weak pull-up
current
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA  +125°C
Min
Typ†
Max
Units
Conditions
50
90
400
A
VDD = 3.0V, VPIN =
VSS
In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended that
the PIC® device be driven with an external clock while in RC mode.
The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified
levels represent normal operating conditions. Higher leakage current may be measured at different input
voltages.
Negative current is defined as current sourced by the pin.
Parameter is characterized but not tested.
DS41303G-page 378
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.9
DC Characteristics: Input/Output Characteristics, PIC18F2XK20/4XK20 (Continued)
DC CHARACTERISTICS
Param
Symbol
No.
VOL
Characteristic
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA  +125°C
Min
Typ†
Max
Units
Conditions
Output Low Voltage
D080
I/O ports
—
—
0.6
V
IOL = 8.5 mA, VDD
= 3.0V,
-40C to +85C
D083
OSC2/CLKOUT
(RC, RCIO, EC, ECIO
modes)
—
—
0.6
V
IOL = 1.6 mA, VDD
= 3.0V,
-40C to +85C
VOH
Output High Voltage(3)
D090
I/O ports
VDD – 0.7
—
—
V
IOH = -3.0 mA, VDD
= 3.0V,
-40C to +85C
D092
OSC2/CLKOUT
(RC, RCIO, EC, ECIO
modes)
VDD – 0.7
—
—
V
IOH = -1.3 mA, VDD
= 3.0V,
-40C to +85C
Capacitive Loading
Specs
on Output Pins
D100(4) COSC2
OSC2 pin
—
—
15
pF
In XT, HS and LP
modes when external clock is used to
drive OSC1
D101
CIO
All I/O pins and OSC2
(in RC mode)
—
—
50
pF
To meet the AC
Timing
Specifications
D102
CB
SCL, SDA
—
—
400
pF
I2C™ Specification
Note 1:
2:
3:
4:
In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended that
the PIC® device be driven with an external clock while in RC mode.
The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified
levels represent normal operating conditions. Higher leakage current may be measured at different input
voltages.
Negative current is defined as current sourced by the pin.
Parameter is characterized but not tested.
 2010 Microchip Technology Inc.
DS41303G-page 379
PIC18F2XK20/4XK20
26.10 Memory Programming Requirements
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C  TA  +125°C
DC CHARACTERISTICS
Param
No.
Sym
Characteristic
Min
Typ†
Max
Units
Conditions
Internal Program Memory
Programming Specifications(1)
D110
VPP
Voltage on MCLR/VPP/RE3 pin
D113
IDDP
Supply Current during
Programming
VDD + 4.5
—
9
V
—
—
10
mA
(Note 3, Note 4)
Data EEPROM Memory
D120
ED
Byte Endurance
100K
—
—
E/W
D121
VDRW
VDD for Read/Write
1.8
—
3.6
V
D122
TDEW
Erase/Write Cycle Time
—
4
—
ms
D123
TRETD Characteristic Retention
40
—
—
Year
Provided no other
specifications are violated
D124
TREF
1M
10M
—
E/W
-40°C to +85°C
D130
EP
Cell Endurance
10K
—
—
E/W
-40C to +85C (NOTE 5)
D131
VPR
VDD for Read
1.8
—
3.6
V
D132
VIW
VDD for Row Erase or Write
2.2
—
3.6
V
D133
TIW
Self-timed Write Cycle Time
D134
TRETD Characteristic Retention
Number of Total Erase/Write
Cycles before Refresh(2)
-40C to +85C
Using EECON to
read/write
Program Flash Memory
—
2
—
ms
40
—
—
Year
Provided no other
specifications are violated
† Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested.
Note 1: These specifications are for programming the on-chip program memory through the use of table write
instructions.
2: Refer to Section 7.8 “Using the Data EEPROM” for a more detailed discussion on data EEPROM
endurance.
3: Required only if single-supply programming is disabled.
4: The MPLAB ICD 2 does not support variable VPP output. Circuitry to limit the ICD 2 VPP voltage must be
placed between the ICD 2 and target system when programming or debugging with the ICD 2.
5: Self-write and Block Erase.
DS41303G-page 380
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.11 Analog Characteristics
TABLE 26-1:
COMPARATOR SPECIFICATIONS
Operating Conditions: 1.8V < VDD < 3.6V, -40°C < TA < +125°C (unless otherwise stated).
Param
No.
CM01
Sym
VIOFF
Characteristics
VICM
Input Common-mode Voltage
CM04
TRESP
Response Time
TMC2OV
*
Note 1:
Typ
Max
Units
—
10
50
mV
VREF = VDD/2,
High Power Mode
—
12
80
mV
VREF = VDD/2,
Low Power Mode
VSS
—
VDD
V
—
200
400
ns
High Power Mode
—
300
600
ns
Low Power Mode
—
—
10
s
Input Offset Voltage
CM02
CM05
Min
Comparator Mode Change to
Output Valid*
Comments
These parameters are characterized but not tested.
Response time measured with one comparator input at VDD/2, while the other input transitions
from VSS to VDD.
TABLE 26-2:
CVREF VOLTAGE REFERENCE SPECIFICATIONS
Operating Conditions: 1.8V < VDD < 3.6V, -40°C < TA < +125°C (unless otherwise stated).
Param
No.
Sym
Characteristics
Min
Typ
Max
Units
VDD/24
VDD/32
—
—
V
V
CLSB
Step Size(2)
—
—
CV02*
CACC
Absolute Accuracy
—
—
1/2
LSb
CV03*
CR
Unit Resistor Value (R)
—
3k
—

CST
Time(1)
—
7.5
10
s
CV01*
CV04*
*
Note 1:
2:
Settling
Comments
Low Range (VRR = 1)
High Range (VRR = 0)
These parameters are characterized but not tested.
Settling time measured while CVRR = 1 and CVR3:CVR0 transitions from ‘0000’ to ‘1111’.
See Section 21.1 “Comparator Voltage Reference” for more information.
TABLE 26-3:
FIXED VOLTAGE REFERENCE (FVR) SPECIFICATIONS
Operating Conditions: 1.8V < VDD < 3.6V, -40°C < TA < +125°C (unless otherwise stated).
VR Voltage Reference Specifications
Param
No.
VR01
Sym
VROUT
Characteristics
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Min
Typ
Max
Units
1.15
1.20
1.25
V
-40°C to +85°C
1.10
1.20
1.30
V
+85°C to +125°C
Voltage drift temperature
coefficient
—
<50
—
VR voltage output
ppm/C -40°C to +40°C (See
Figure 27-34)
VR02*
TCVOUT
VR03*
VROUT/
VDD
Voltage drift with respect to
VDD regulation
—
<2000
—
V/V
VR04*
TSTABLE
Settling Time
—
25
100
s
*
Comments
25°C, 2.0 to 3.3V (See
Figure 27-33)
0 to 125°C
These parameters are characterized but not tested.
 2010 Microchip Technology Inc.
DS41303G-page 381
PIC18F2XK20/4XK20
FIGURE 26-3:
HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
VDD
(HLVDIF can be
cleared by software)
VHLVD
(HLVDIF set by hardware)
HLVDIF
TABLE 26-4:
HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C  TA  +125°C
Param
Symbol
No.
D420
Characteristic
HLVD Voltage on
VDD Transition
High-to-Low
Min
Typ†
Max
Units
HLVDL<3:0> = 0000
1.70
1.85
2.00
V
HLVDL<3:0> = 0001
1.80
1.95
2.10
V
HLVDL<3:0> = 0010
1.91
2.06
2.21
V
HLVDL<3:0> = 0011
2.02
2.17
2.32
V
HLVDL<3:0> = 0100
2.15
2.30
2.45
V
HLVDL<3:0> = 0101
2.22
2.37
2.52
V
HLVDL<3:0> = 0110
2.38
2.53
2.68
V
HLVDL<3:0> = 0111
2.46
2.61
2.76
V
HLVDL<3:0> = 1000
2.55
2.70
2.85
V
HLVDL<3:0> = 1001
2.65
2.80
2.95
V
HLVDL<3:0> = 1010
2.75
2.90
3.05
V
HLVDL<3:0> = 1011
2.87
3.02
3.17
V
HLVDL<3:0> = 1100
2.98
3.13
3.28
V
HLVDL<3:0> = 1101
3.26
3.41
3.56
V
HLVDL<3:0> = 1110
3.42
3.57
3.72
V
Conditions
† Production tested at TAMB = 25°C. Specifications over temperature limits ensured by characterization.
DS41303G-page 382
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
26.12 AC (Timing) Characteristics
26.12.1
TIMING PARAMETER SYMBOLOGY
The timing parameter symbols have been created
using one of the following formats:
1. TppS2ppS
2. TppS
T
F
Frequency
Lowercase letters (pp) and their meanings:
pp
cc
CCP1
ck
CLKOUT
cs
CS
di
SDI
do
SDO
dt
Data in
io
I/O port
mc
MCLR
Uppercase letters and their meanings:
S
F
Fall
H
High
I
Invalid (High-impedance)
L
Low
I2C only
AA
output access
BUF
Bus free
TCC:ST (I2C specifications only)
CC
HD
Hold
ST
DAT
DATA input hold
STA
Start condition
 2010 Microchip Technology Inc.
3. TCC:ST
4. Ts
(I2C™ specifications only)
(I2C specifications only)
T
Time
osc
rd
rw
sc
ss
t0
t1
wr
OSC1
RD
RD or WR
SCK
SS
T0CKI
T13CKI
WR
P
R
V
Z
Period
Rise
Valid
High-impedance
High
Low
High
Low
SU
Setup
STO
Stop condition
DS41303G-page 383
PIC18F2XK20/4XK20
26.12.2
TIMING CONDITIONS
The temperature and voltages specified in Table 26-5
apply to all timing specifications unless otherwise
noted. Figure 26-4 specifies the load conditions for the
timing specifications.
TABLE 26-5:
TEMPERATURE AND VOLTAGE SPECIFICATIONS – AC
AC CHARACTERISTICS
FIGURE 26-4:
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA +125°C
Operating voltage VDD range as described in DC spec Section 26.1 and
Section 26.9.
LOAD CONDITIONS FOR DEVICE TIMING SPECIFICATIONS
Load Condition 1
Load Condition 2
VDD/2
RL
CL
Pin
VSS
CL
Pin
RL = 464
VSS
26.12.3
CL = 50 pF
for all pins except OSC2/CLKOUT
and including D and E outputs as ports
TIMING DIAGRAMS AND SPECIFICATIONS
FIGURE 26-5:
EXTERNAL CLOCK TIMING (ALL MODES EXCEPT PLL)
Q4
Q1
Q2
Q3
Q4
Q1
OSC1
1
3
3
4
4
2
CLKOUT
DS41303G-page 384
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 26-6:
Param.
No.
1A
EXTERNAL CLOCK TIMING REQUIREMENTS
Symbol
FOSC
Characteristic
External CLKIN
Frequency(1)
Oscillator Frequency(1)
1
TOSC
External CLKIN Period(1)
Oscillator Period(1)
Time(1)
2
TCY
Instruction Cycle
3
TOSL,
TOSH
External Clock in (OSC1)
High or Low Time
4
Note 1:
TOSR,
TOSF
External Clock in (OSC1)
Rise or Fall Time
Min
Max
Units
Conditions
DC
48
MHz
EC, ECIO Oscillator mode,
(Extended Range Devices)
DC
64
MHz
EC, ECIO Oscillator mode,
(Industrial Range Devices)
DC
4
MHz
RC Oscillator mode
0.1
4
MHz
XT Oscillator mode
4
25
MHz
HS Oscillator mode
4
16
MHz
HS + PLL Oscillator mode,
(Industrial Range Devices)
4
12
MHz
HS + PLL Oscillator mode,
(Extended Range Devices)
LP Oscillator mode
5
200
kHz
20.8
—
ns
EC, ECIO, Oscillator mode
(Extended Range Devices)
15.6
—
ns
EC, ECIO, Oscillator mode,
(Industrial Range Devices)
250
—
ns
RC Oscillator mode
250
10,000
ns
XT Oscillator mode
40
62.5
250
250
ns
ns
83.3
250
ns
HS Oscillator mode
HS + PLL Oscillator mode,
(Industrial range devices)
HS + PLL Oscillator mode,
(Extended Range Devices)
5
200
s
LP Oscillator mode
62.5
—
ns
TCY = 4/FOSC
30
—
ns
XT Oscillator mode
2.5
—
s
LP Oscillator mode
10
—
ns
HS Oscillator mode
—
20
ns
XT Oscillator mode
—
50
ns
LP Oscillator mode
—
7.5
ns
HS Oscillator mode
Instruction cycle period (TCY) equals four times the input oscillator time base period for all configurations
except PLL. All specified values are based on characterization data for that particular oscillator type under
standard operating conditions with the device executing code. Exceeding these specified limits may result
in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested
to operate at “min.” values with an external clock applied to the OSC1/CLKIN pin. When an external clock
input is used, the “max.” cycle time limit is “DC” (no clock) for all devices.
 2010 Microchip Technology Inc.
DS41303G-page 385
PIC18F2XK20/4XK20
TABLE 26-7:
Param
No.
PLL CLOCK TIMING SPECIFICATIONS (VDD = 1.8V TO 3.6V)
Sym
F10
Characteristic
FOSC Oscillator Frequency Range
F11
FSYS
On-Chip VCO System Frequency
Min
Typ†
Max
Units
4
—
4
MHz VDD = 1.8-2.0V
4
—
5
MHz VDD = 2.0-3.0V
4
—
16
MHz VDD = 3.0-3.6V,
Industrial Range Devices
4
—
12
MHz VDD = 3.0-3.6V,
Extended Range Devices
16
—
16
MHz VDD = 1.8-2.0V
16
—
20
MHz VDD = 2.0-3.0V
16
—
64
MHz VDD = 3.0-3.6V,
Industrial Range Devices
16
—
48
MHz VDD = 3.0-3.6V,
Extended Range Devices
F12
trc
PLL Start-up Time (Lock Time)
—
—
2
ms
F13
CLK
CLKOUT Stability (Jitter)
-2
—
+2
%
TABLE 26-8:
AC CHARACTERISTICS: INTERNAL OSCILLATORS ACCURACY
PIC18F2XK20/4XK20
PIC18F2XK20/4XK20
Param
No.
OA1
OA2
Conditions
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Min
Typ
Max
Units
Conditions
HFINTOSC Accuracy @ Freq = 16 MHz, 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz(1)
-2
0
+2
%
+0°C to +70°C
VDD = 1.8-3.6V
-3
—
+2
%
+70°C to +85°C
VDD = 1.8-3.6V
-5
—
+5
%
-40°C to 0°C and
+85°C to 125°C
VDD = 1.8-3.6V
—
+15
%
-40°C to +125°C
VDD = 1.8-3.6V
LFINTOSC Accuracy @ Freq = 31.25 kHz
-15
Note 1:
Frequency calibrated at 25°C. OSCTUNE register can be used to compensate for temperature drift.
DS41303G-page 386
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 26-6:
CLKOUT AND I/O TIMING
Q1
Q4
Q2
Q3
OSC1
11
10
CLKOUT
13
14
19
12
18
16
I/O pin
(Input)
15
17
I/O pin
(Output)
Note:
20, 21
Refer to Figure 26-4 for load conditions.
TABLE 26-9:
Param
No.
New Value
Old Value
CLKOUT AND I/O TIMING REQUIREMENTS
Symbol
Characteristic
Min
Typ
Max
Units Conditions
10
TosH2ckL OSC1  to CLKOUT 
—
75
200
ns
(Note 1)
11
TosH2ckH OSC1  to CLKOUT 
—
75
200
ns
(Note 1)
12
TckR
CLKOUT Rise Time
—
35
100
ns
(Note 1)
13
TckF
CLKOUT Fall Time
—
35
100
ns
(Note 1)
CLKOUT  to Port Out Valid
—
—
0.5 TCY + 20
ns
(Note 1)
0.25 TCY + 25
—
—
ns
(Note 1)
(Note 1)
14
TckL2ioV
15
TioV2ckH Port In Valid before CLKOUT 
Port In Hold after CLKOUT 
16
TckH2ioI
17
TosH2ioV OSC1  (Q1 cycle) to Port Out Valid
0
—
—
ns
—
50
150
ns
18
TosH2ioI
100
—
—
ns
19
TioV2osH Port Input Valid to OSC1 (I/O in setup
time)
0
—
—
ns
20
TioR
Port Output Rise Time
—
10
25
ns
21
TioF
Port Output Fall Time
—
10
25
ns
22†
TINP
INTx pin High or Low Time
20
—
—
ns
23†
TRBP
RB<7:4> Change KBIx High or Low Time
TCY
—
—
ns
OSC1  (Q2 cycle) to Port Input Invalid
(I/O in hold time)
† These parameters are asynchronous events not related to any internal clock edges.
Note 1: Measurements are taken in RC mode, where CLKOUT output is 4 x TOSC.
 2010 Microchip Technology Inc.
DS41303G-page 387
PIC18F2XK20/4XK20
FIGURE 26-7:
RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND
POWER-UP TIMER TIMING
VDD
MCLR
30
Internal
POR
33
PWRT
Time-out
32
OSC
Time-out
Internal
Reset
Watchdog
Timer
Reset
31
34
34
I/O pins
Note:
Refer to Figure 26-4 for load conditions.
FIGURE 26-8:
BROWN-OUT RESET TIMING
BVDD
VDD
35
VBGAP = 1.2V
VIVRST
Enable Internal
Reference Voltage
Internal Reference
Voltage Stable
36
TABLE 26-10: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER
AND BROWN-OUT RESET REQUIREMENTS
Param.
Symbol
No.
30
31
TmcL
TWDT
32
33
TOST
TPWRT
34
TIOZ
35
36
37
38
39
TBOR
TIVRST
THLVD
TCSD
TIOBST
Characteristic
MCLR Pulse Width (low)
Watchdog Timer Time-out Period
(no postscaler)
Oscillation Start-up Timer Period
Power-up Timer Period
I/O High-Impedance from MCLR
Low or Watchdog Timer Reset
Brown-out Reset Pulse Width
Internal Reference Voltage Stable
High/Low-Voltage Detect Pulse Width
CPU Start-up Time
Time for HF-INTOSC to Stabilize
DS41303G-page 388
Min
Typ
Max
Units
2
3.5
—
4.1
—
4.7
s
ms
1024 TOSC — 1024 TOSC
54.8
64.4
74.1
—
ms
—
2
—
s
200
—
200
5
—
—
25
—
—
0.25
—
35
—
10
1
s
s
s
s
ms
Conditions
1:1 prescaler
TOSC = OSC1 period
VDD  BVDD (see D005)
VDD  VHLVD
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 26-9:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI
41
40
42
T1OSO/T13CKI
46
45
47
48
TMR0 or
TMR1
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-11: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
No.
Symbol
Characteristic
40
Tt0H
T0CKI High Pulse Width
41
Tt0L
T0CKI Low Pulse Width
42
Tt0P
T0CKI Period
No prescaler
With prescaler
No prescaler
With prescaler
No prescaler
With prescaler
45
46
Tt1H
Tt1L
Tt1P
Ft1
Units Conditions
0.5 TCY + 20
—
ns
10
—
ns
0.5 TCY + 20
—
ns
10
—
ns
TCY + 10
—
ns
Greater of:
20 ns or
(TCY + 40)/N
—
ns
0.5 TCY + 20
—
ns
10
—
ns
Asynchronous
30
—
ns
T13CKI Low Synchronous, no prescaler
Time
Synchronous,
with prescaler
0.5 TCY + 5
—
ns
10
—
ns
Synchronous, no prescaler
T13CKI
Synchronous
Input Period
Asynchronous
48
Max
Synchronous,
with prescaler
T13CKI
High Time
Asynchronous
47
Min
T13CKI Clock Input Frequency Range
Tcke2tmrI Delay from External T13CKI Clock Edge to
Timer Increment
 2010 Microchip Technology Inc.
30
—
ns
Greater of:
20 ns or
(TCY + 40)/N
—
ns
60
—
ns
DC
50
kHz
2 TOSC
7 TOSC
—
N = prescale
value
(1, 2, 4,..., 256)
N = prescale
value (1, 2, 4, 8)
DS41303G-page 389
PIC18F2XK20/4XK20
FIGURE 26-10:
CAPTURE/COMPARE/PWM TIMINGS (ALL CCP MODULES)
CCPx
(Capture Mode)
50
51
52
CCPx
(Compare or PWM Mode)
53
Note:
54
Refer to Figure 26-4 for load conditions.
TABLE 26-12: CAPTURE/COMPARE/PWM REQUIREMENTS (ALL CCP MODULES)
Param
Symbol
No.
50
51
TccL
TccH
Characteristic
Min
Max
Units
CCPx Input Low No prescaler
Time
With
prescaler
0.5 TCY + 20
—
ns
10
—
ns
CCPx Input
High Time
0.5 TCY + 20
—
ns
10
—
ns
3 TCY + 40
N
—
ns
No prescaler
With
prescaler
52
TccP
CCPx Input Period
53
TccR
CCPx Output Fall Time
—
25
ns
54
TccF
CCPx Output Fall Time
—
25
ns
DS41303G-page 390
Conditions
N = prescale
value (1, 4 or 16)
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 26-11:
PARALLEL SLAVE PORT TIMING (PIC18F4XK20)
RE2/CS
RE0/RD
RE1/WR
65
RD7:RD0
62
64
63
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-13: PARALLEL SLAVE PORT REQUIREMENTS (PIC18F4XK20)
Param.
No.
Symbol
Characteristic
Min
Max
Units
62
TdtV2wrH
Data In Valid before WR  or CS 
(setup time)
20
—
ns
63
TwrH2dtI
WR  or CS  to Data–In Invalid (hold time)
20
—
ns
64
TrdL2dtV
RD  and CS  to Data–Out Valid
—
80
ns
65
TrdH2dtI
RD  or CS  to Data–Out Invalid
10
30
ns
66
TibfINH
Inhibit of the IBF Flag bit being Cleared from
WR  or CS 
—
3 TCY
 2010 Microchip Technology Inc.
Conditions
DS41303G-page 391
PIC18F2XK20/4XK20
FIGURE 26-12:
EXAMPLE SPI MASTER MODE TIMING (CKE = 0)
SS
70
SCK
(CKP = 0)
71
72
78
79
79
78
SCK
(CKP = 1)
80
bit 6 - - - - - -1
MSb
SDO
LSb
75, 76
SDI
MSb In
bit 6 - - - -1
LSb In
74
73
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-14: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 0)
Param
No.
Symbol
Characteristic
Min
Max Units
70
TssL2scH,
TssL2scL
SS  to SCK  or SCK  Input
71
TscH
SCK Input High Time
(Slave mode)
Continuous
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
SCK Input Low Time
(Slave mode)
Continuous
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
100
—
ns
1.5 TCY + 40
—
ns
100
—
ns
71A
72
TscL
72A
TCY
—
ns
73
TdiV2scH,
TdiV2scL
Setup Time of SDI Data Input to SCK Edge
73A
Tb2b
Last Clock Edge of Byte 1 to the 1st Clock Edge
of Byte 2
74
TscH2diL,
TscL2diL
Hold Time of SDI Data Input to SCK Edge
75
TdoR
SDO Data Output Rise Time
—
25
ns
76
TdoF
SDO Data Output Fall Time
—
25
ns
78
TscR
SCK Output Rise Time
(Master mode)
—
25
ns
79
TscF
SCK Output Fall Time (Master mode)
—
25
ns
80
TscH2doV,
TscL2doV
SDO Data Output Valid after SCK Edge
—
50
ns
Note 1:
2:
Conditions
(Note 1)
(Note 1)
(Note 2)
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
DS41303G-page 392
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 26-13:
EXAMPLE SPI MASTER MODE TIMING (CKE = 1)
SS
81
SCK
(CKP = 0)
71
72
79
73
SCK
(CKP = 1)
80
78
MSb
SDO
bit 6 - - - - - -1
LSb
bit 6 - - - -1
LSb In
75, 76
SDI
MSb In
74
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-15: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 1)
Param.
No.
71
Symbol
Characteristic
TscH
SCK Input High Time
(Slave mode)
TscL
SCK Input Low Time
(Slave mode)
73
TdiV2scH,
TdiV2scL
Setup Time of SDI Data Input to SCK Edge
73A
Tb2b
Last Clock Edge of Byte 1 to the 1st Clock Edge
of Byte 2
74
TscH2diL,
TscL2diL
Hold Time of SDI Data Input to SCK Edge
75
TdoR
SDO Data Output Rise Time
71A
72
72A
Continuous
Min
Max Units
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
Continuous
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
100
—
ns
1.5 TCY + 40
—
ns
100
—
ns
—
25
ns
76
TdoF
SDO Data Output Fall Time
—
25
ns
78
TscR
SCK Output Rise Time
(Master mode)
—
25
ns
79
TscF
SCK Output Fall Time (Master mode)
—
25
ns
80
TscH2doV,
TscL2doV
SDO Data Output Valid after SCK Edge
—
50
ns
81
TdoV2scH,
TdoV2scL
SDO Data Output Setup to SCK Edge
TCY
—
ns
Note 1:
2:
Conditions
(Note 1)
(Note 1)
(Note 2)
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
 2010 Microchip Technology Inc.
DS41303G-page 393
PIC18F2XK20/4XK20
FIGURE 26-14:
EXAMPLE SPI SLAVE MODE TIMING (CKE = 0)
SS
70
SCK
(CKP = 0)
83
71
72
78
79
79
78
SCK
(CKP = 1)
80
MSb
SDO
bit 6 - - - - - -1
LSb
77
75, 76
MSb In
SDI
73
Note:
bit 6 - - - -1
LSb In
74
Refer to Figure 26-4 for load conditions.
TABLE 26-16: EXAMPLE SPI MODE REQUIREMENTS (SLAVE MODE TIMING, CKE = 0)
Param
No.
Symbol
Characteristic
70
TssL2scH, SS  to SCK  or SCK  Input
TssL2scL
71
TscH
71A
72
TscL
72A
Min
Max Units Conditions
TCY
—
ns
SCK Input High Time
(Slave mode)
Continuous
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
SCK Input Low Time
(Slave mode)
Continuous
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
100
—
ns
73
TdiV2scH, Setup Time of SDI Data Input to SCK Edge
TdiV2scL
73A
Tb2b
74
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40
—
ns
100
—
ns
75
TdoR
SDO Data Output Rise Time
—
25
ns
76
TdoF
SDO Data Output Fall Time
—
25
ns
77
TssH2doZ SS to SDO Output High-Impedance
10
50
ns
78
TscR
SCK Output Rise Time (Master mode)
—
25
ns
79
TscF
SCK Output Fall Time (Master mode)
—
25
ns
80
TscH2doV SDO Data Output Valid after SCK Edge
,
TscL2doV
—
50
ns
83
TscH2ssH SS  after SCK edge
,
TscL2ssH
1.5 TCY + 40
—
ns
Note 1:
2:
(Note 1)
(Note 1)
(Note 2)
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
DS41303G-page 394
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 26-15:
EXAMPLE SPI SLAVE MODE TIMING (CKE = 1)
82
SS
SCK
(CKP = 0)
70
83
71
72
SCK
(CKP = 1)
80
MSb
SDO
bit 6 - - - - - -1
LSb
75, 76
SDI
MSb In
Note:
77
bit 6 - - - -1
LSb In
74
Refer to Figure 26-4 for load conditions.
TABLE 26-17: EXAMPLE SPI SLAVE MODE REQUIREMENTS (CKE = 1)
Param
No.
Symbol
Characteristic
Min
70
TssL2scH, SS  to SCK  or SCK  Input
TssL2scL
71
TscH
SCK Input High Time
(Slave mode)
TscL
SCK Input Low Time
(Slave mode)
73A
Tb2b
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40
74
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
75
TdoR
SDO Data Output Rise Time
76
TdoF
SDO Data Output Fall Time
77
TssH2doZ SS to SDO Output High-Impedance
78
TscR
SCK Output Rise Time
(Master mode)
79
TscF
SCK Output Fall Time (Master mode)
80
Max Units Conditions
TCY
—
ns
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
Continuous
1.25 TCY + 30
—
ns
Single Byte
40
—
ns
(Note 1)
—
ns
(Note 2)
100
—
ns
—
25
ns
—
25
ns
10
50
ns
—
25
ns
—
25
ns
TscH2doV, SDO Data Output Valid after SCK Edge
TscL2doV
—
50
ns
82
TssL2doV SDO Data Output Valid after SS  Edge
—
50
ns
83
TscH2ssH SS  after SCK Edge
,
TscL2ssH
1.5 TCY + 40
—
ns
71A
72
72A
Note 1:
2:
Continuous
(Note 1)
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
 2010 Microchip Technology Inc.
DS41303G-page 395
PIC18F2XK20/4XK20
I2C™ BUS START/STOP BITS TIMING
FIGURE 26-16:
SCL
91
93
90
92
SDA
Stop
Condition
Start
Condition
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-18: I2C™ BUS START/STOP BITS REQUIREMENTS (SLAVE MODE)
Param.
Symbol
No.
Characteristic
90
TSU:STA
Start Condition
91
THD:STA
92
TSU:STO
93
THD:STO Stop Condition
Max
Units
Conditions
4700
—
ns
Only relevant for Repeated
Start condition
ns
After this period, the first
clock pulse is generated
Setup Time
400 kHz mode
600
—
Start Condition
100 kHz mode
4000
—
Hold Time
400 kHz mode
600
—
Stop Condition
100 kHz mode
4700
—
Setup Time
Hold Time
FIGURE 26-17:
100 kHz mode
Min
400 kHz mode
600
—
100 kHz mode
4000
—
400 kHz mode
600
—
ns
ns
I2C™ BUS DATA TIMING
103
102
100
101
SCL
90
106
107
91
92
SDA
In
110
109
109
SDA
Out
Note:
Refer to Figure 26-4 for load conditions.
DS41303G-page 396
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 26-19: I2C™ BUS DATA REQUIREMENTS (SLAVE MODE)
Param.
Symbol
No.
100
THIGH
Characteristic
Clock High Time
Min
Max
Units
100 kHz mode
4.0
—
s
PIC18FXXXX must operate
at a minimum of 1.5 MHz
400 kHz mode
0.6
—
s
PIC18FXXXX must operate
at a minimum of 10 MHz
1.5 TCY
—
100 kHz mode
4.7
—
s
PIC18FXXXX must operate
at a minimum of 1.5 MHz
400 kHz mode
1.3
—
s
PIC18FXXXX must operate
at a minimum of 10 MHz
SSP Module
101
TLOW
Clock Low Time
1.5 TCY
—
—
1000
ns
20 + 0.1 CB
300
ns
100 kHz mode
—
300
ns
400 kHz mode
20 + 0.1 CB
300
ns
CB is specified to be from
10 to 400 pF
TSU:STA Start Condition
Setup Time
100 kHz mode
4.7
—
s
400 kHz mode
0.6
—
s
Only relevant for Repeated
Start condition
THD:STA Start Condition
Hold Time
100 kHz mode
4.0
—
s
400 kHz mode
0.6
—
s
THD:DAT Data Input Hold
Time
100 kHz mode
0
—
ns
400 kHz mode
0
0.9
s
TSU:DAT Data Input Setup
Time
100 kHz mode
250
—
ns
400 kHz mode
100
—
ns
TSU:STO Stop Condition
Setup Time
100 kHz mode
4.7
—
s
400 kHz mode
0.6
—
s
SSP Module
102
TR
103
TF
90
91
106
107
92
109
TAA
110
TBUF
D102
CB
Note 1:
2:
Conditions
SDA and SCL Rise 100 kHz mode
Time
400 kHz mode
SDA and SCL Fall
Time
Output Valid from
Clock
100 kHz mode
—
3500
ns
400 kHz mode
—
—
ns
Bus Free Time
100 kHz mode
4.7
—
s
400 kHz mode
1.3
—
s
—
400
pF
Bus Capacitive Loading
CB is specified to be from
10 to 400 pF
After this period, the first
clock pulse is generated
(Note 2)
(Note 1)
Time the bus must be free
before a new transmission
can start
As a transmitter, the device must provide this internal minimum delay time to bridge the undefined region
(min. 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions.
A fast mode I2C bus device can be used in a standard mode I2C bus system but the requirement,
TSU:DAT  250 ns, must then be met. This will automatically be the case if the device does not stretch the
LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must
output the next data bit to the SDA line, TR max. + TSU:DAT = 1000 + 250 = 1250 ns (according to the
standard mode I2C bus specification), before the SCL line is released.
 2010 Microchip Technology Inc.
DS41303G-page 397
PIC18F2XK20/4XK20
FIGURE 26-18:
MASTER SSP I2C™ BUS START/STOP BITS TIMING WAVEFORMS
SCL
93
91
90
92
SDA
Stop
Condition
Start
Condition
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-20: MASTER SSP I2C™ BUS START/STOP BITS REQUIREMENTS
Param.
Symbol
No.
90
TSU:STA
Characteristic
Start Condition
100 kHz mode
Setup Time
91
THD:STA Start Condition
Hold Time
92
TSU:STO Stop Condition
Setup Time
93
THD:STO Stop Condition
Hold Time
Min
Max
Units
2(TOSC)(BRG + 1)
—
ns
Only relevant for
Repeated Start
condition
ns
After this period, the
first clock pulse is
generated
400 kHz mode
2(TOSC)(BRG + 1)
—
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
100 kHz mode
2(TOSC)(BRG + 1)
—
400 kHz mode
2(TOSC)(BRG + 1)
—
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
100 kHz mode
2(TOSC)(BRG + 1)
—
400 kHz mode
2(TOSC)(BRG + 1)
—
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
100 kHz mode
2(TOSC)(BRG + 1)
—
400 kHz mode
2(TOSC)(BRG + 1)
—
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
Conditions
ns
ns
Note 1: Maximum pin capacitance = 10 pF for all I2C pins.
FIGURE 26-19:
MASTER SSP I2C™ BUS DATA TIMING
103
102
100
101
SCL
90
106
91
107
92
SDA
In
109
109
110
SDA
Out
Note:
DS41303G-page 398
Refer to Figure 26-4 for load conditions.
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 26-21: MASTER SSP I2C™ BUS DATA REQUIREMENTS
Param.
Symbol
No.
100
THIGH
Characteristic
Min
Max
Units
2(TOSC)(BRG + 1)
—
ms
2(TOSC)(BRG
+ 1)
—
ms
mode(1)
2(TOSC)(BRG + 1)
—
ms
Clock Low Time 100 kHz mode
2(TOSC)(BRG + 1)
—
ms
400 kHz mode
2(TOSC)(BRG + 1)
—
ms
mode(1)
ms
Clock High Time 100 kHz mode
400 kHz mode
1 MHz
101
TLOW
1 MHz
102
103
90
91
TR
TF
TSU:STA
SDA and SCL
Rise Time
SDA and SCL
Fall Time
Start Condition
Setup Time
THD:STA Start Condition
Hold Time
2(TOSC)(BRG + 1)
—
100 kHz mode
—
1000
ns
400 kHz mode
20 + 0.1 CB
300
ns
1 MHz mode(1)
—
300
ns
100 kHz mode
—
300
ns
400 kHz mode
20 + 0.1 CB
300
ns
1 MHz mode(1)
—
100
ns
100 kHz mode
2(TOSC)(BRG + 1)
—
ms
400 kHz mode
2(TOSC)(BRG
+ 1)
—
ms
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
ms
100 kHz mode
2(TOSC)(BRG + 1)
—
ms
400 kHz mode
2(TOSC)(BRG + 1)
—
ms
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
ms
0
—
ns
106
THD:DAT Data Input
Hold Time
100 kHz mode
400 kHz mode
0
0.9
ms
107
TSU:DAT
100 kHz mode
250
—
ns
400 kHz mode
100
—
ns
92
TSU:STO Stop Condition
Setup Time
100 kHz mode
2(TOSC)(BRG + 1)
—
ms
400 kHz mode
2(TOSC)(BRG + 1)
—
ms
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
ms
100 kHz mode
—
3500
ns
400 kHz mode
ns
109
TAA
Data Input
Setup Time
Output Valid
from Clock
—
1000
mode(1)
—
—
ns
100 kHz mode
4.7
—
ms
400 kHz mode
1.3
—
ms
—
400
pF
1 MHz
110
D102
Note 1:
2:
TBUF
CB
Bus Free Time
Bus Capacitive Loading
Conditions
CB is specified to be from
10 to 400 pF
CB is specified to be from
10 to 400 pF
Only relevant for
Repeated Start
condition
After this period, the first
clock pulse is generated
(Note 2)
Time the bus must be free
before a new transmission
can start
I2C
Maximum pin capacitance = 10 pF for all
pins.
A fast mode I2C bus device can be used in a standard mode I2C bus system, but parameter 107  250 ns
must then be met. This will automatically be the case if the device does not stretch the LOW period of the
SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit
to the SDA line, parameter 102 + parameter 107 = 1000 + 250 = 1250 ns (for 100 kHz mode), before the
SCL line is released.
 2010 Microchip Technology Inc.
DS41303G-page 399
PIC18F2XK20/4XK20
FIGURE 26-20:
EUSART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
RC6/TX/CK
pin
121
121
RC7/RX/DT
pin
120
Note:
122
Refer to Figure 26-4 for load conditions.
TABLE 26-22: EUSART SYNCHRONOUS TRANSMISSION REQUIREMENTS
Param
No.
Symbol
Characteristic
Min
Max
Units
120
TckH2dtV SYNC XMIT (MASTER & SLAVE)
Clock High to Data Out Valid
—
40
ns
121
Tckrf
Clock Out Rise Time and Fall Time
(Master mode)
—
20
ns
122
Tdtrf
Data Out Rise Time and Fall Time
—
20
ns
FIGURE 26-21:
RC6/TX/CK
pin
Conditions
EUSART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
125
RC7/RX/DT
pin
126
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-23: EUSART SYNCHRONOUS RECEIVE REQUIREMENTS
Param.
No.
Symbol
Characteristic
Min
Max
Units
125
TdtV2ckl
SYNC RCV (MASTER & SLAVE)
Data Setup before CK  (DT setup time)
10
—
ns
126
TckL2dtl
Data Hold after CK  (DT hold time)
15
—
ns
DS41303G-page 400
Conditions
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
TABLE 26-24: A/D CONVERTER CHARACTERISTICS: PIC18F2XK20/4XK20
Param
Symbol
No.
Characteristic
Min
Typ
Max
Units
Conditions
A01
NR
Resolution
—
—
10
bits -40°C to +85°C, VREF
 2.0V
A03
EIL
Integral Linearity Error
—
±0.5
±1
LSb -40°C to +85°C, VREF
 2.0V
A04
EDL
Differential Linearity Error
—
±0.4
±1
LSb -40°C to +85°C, VREF
 2.0V
A06
EOFF
Offset Error
—
0.4
±2
LSb -40°C to +85°C, VREF
 2.0V
A07
EGN
Gain Error
—
0.3
±2
LSb -40°C to +85°C, VREF
 2.0V
A08
ETOTL
Total Error
—
1
±3
LSb -40°C to +85°C, VREF
 2.0V
A20
VREF
Reference Voltage Range
(VREFH – VREFL)
1.8
2.0
—
—
—
—
A21
VREFH
Reference Voltage High
VDD/2
—
VDD + 0.3
V
A22
VREFL
Reference Voltage Low
VSS – 0.3V
—
VDD/2
V
A25
VAIN
Analog Input Voltage
VREFL
—
VREFH
V
A30
ZAIN
Recommended Impedance of
Analog Voltage Source
—
—
3
k
Note 1:
2:
V
V
ABsolute Minimum
Minimum for 1LSb
Accuracy
-40°C to +85°C
The A/D conversion result never decreases with an increase in the input voltage and has no missing
codes.
VREFH current is from RA3/AN3/VREF+ pin or VDD, whichever is selected as the VREFH source.
VREFL current is from RA2/AN2/VREF-/CVREF pin or VSS, whichever is selected as the VREFL source.
 2010 Microchip Technology Inc.
DS41303G-page 401
PIC18F2XK20/4XK20
FIGURE 26-22:
A/D CONVERSION TIMING
BSF ADCON0, GO
(Note 2)
131
Q4
130
132
A/D CLK
9
A/D DATA
8
7
.. .
...
2
1
0
NEW_DATA
OLD_DATA
ADRES
TCY
ADIF
GO
DONE
SAMPLING STOPPED
SAMPLE
Note
1:
If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock starts.
This allows the SLEEP instruction to be executed.
2:
This is a minimal RC delay (typically 100 ns), which also disconnects the holding capacitor from the analog input.
TABLE 26-25: A/D CONVERSION REQUIREMENTS
Param
Symbol
No.
130
TAD
Characteristic
A/D Clock Period
Min
Max
Units
0.7
25.0(1)
s
TOSC based,
-40C to +85C
0.7
4.0(1)
s
TOSC based,
+85C to +125C
1.0
4.0
s
FRC mode, VDD2.0V
131
TCNV
Conversion Time
(not including acquisition time) (Note 2)
12
12
TAD
132
TACQ
Acquisition Time (Note 3)
1.4
—
s
135
TSWC
Switching Time from Convert  Sample
—
(Note 4)
136
TDIS
Discharge Time
2
2
Legend:
Note 1:
2:
3:
4:
Conditions
VDD = 3V, Rs = 50
TAD
TBD = To Be Determined
The time of the A/D clock period is dependent on the device frequency and the TAD clock divider.
ADRES register may be read on the following TCY cycle.
The time for the holding capacitor to acquire the “New” input voltage when the voltage changes full scale
after the conversion (VDD to VSS or VSS to VDD). The source impedance (RS) on the input channels is 50
.
On the following cycle of the device clock.
DS41303G-page 402
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
27.0
DC AND AC CHARACTERISTICS GRAPHS AND TABLES
FIGURE 27-1:
PIC18F4XK20/PIC18F2XK20 TYPICAL BASE IPD
10
125°C
1
IPD (uA)
85°C
0.1
40°C
Limited Accuracy
25°C
-40°C
0.01
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-2:
PIC184XK20/PIC18F2XK20 MAXIMUM BASE IPD
100
IPD (uA)
125°C
10
85°C
40°C
25°C
1
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 403
PIC18F2XK20/4XK20
FIGURE 27-3:
PIC18F4XK20/PIC18F2XK20 TYPICAL RC_RUN 31 KHZ IDD
16
125°C
14
IDD (uA)
12
85°C
25°C
-40°C
10
8
6
4
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-4:
PIC18F4XK20/PIC18F2XK20 MAXIMUM RC_RUN 31 KHZ IDD
45
125°C
40
35
IDD (uA)
30
25
20
85°C
15
25°C
-40°C
10
5
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
DS41303G-page 404
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-5:
PIC18F4XK20/PIC18F2XK20 TYPICAL RC_RUN IDD
5.0
4.5
4.0
16 MHz
3.5
IDD (mA)
3.0
2.5
8 MHz
2.0
1.5
4 M Hz
1.0
1 MHz
0.5
0.0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-6:
PIC18F4XK20/PIC18F2XK20 MAXIMUM RC_RUN IDD
6
5
16 MHz
IDD (mA)
4
8 MHz
3
2
4 MHz
1
1 MHz
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 405
PIC18F2XK20/4XK20
FIGURE 27-7:
PIC18F4XK20/PIC18F2XK20 TYPICAL RC_IDLE 31 KHZ IDD
7
125°C
6
IDD (uA)
5
85°C
4
25°C
-40°C
3
2
1
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.4
3.6
VDD (V)
FIGURE 27-8:
PIC18F4XK20/PIC18F2XK20 MAXIMUM RC_IDLE 31 KHZ IDD
35
125°C
30
25
IDD (uA)
20
15
85°C
10
25°C
-40°C
5
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
VDD (V)
DS41303G-page 406
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-9:
PIC18F4XK20/PIC18F2XK20 TYPICAL RC_IDLE IDD
2.5
2.0
16 MHz
IDD (mA)
1.5
8 MHz
1.0
4 MHz
0.5
1 MHz
0.0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-10:
PIC18F4XK20/PIC18F2XK20 MAXIMUM RC_IDLE IDD
3.0
2.5
16 MHz
IDD (mA)
2.0
1.5
8 MHz
1.0
4 MHz
1 MHz
0.5
0.0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 407
PIC18F2XK20/4XK20
FIGURE 27-11:
PIC18F4XK20/PIC18F2XK20 TYPICAL PRI_RUN IDD (EC)
16
14
64 MHz
12
IDD (mA)
10
40 MHz
8
6
20 MHz
4
16 MHz
10 MHz
2
4 MHz
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.4
3.6
VDD (V)
FIGURE 27-12:
PIC18F4XK20/PIC18F2XK20 MAXIMUM PRI_RUN IDD (EC)
18
16
64 MHz
14
IDD (mA)
12
10
40 MHz
8
6
20 MHz
16 MHz
4
10 MHz
2
4 MHz
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
VDD (V)
DS41303G-page 408
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-13:
PIC18F4XK20/PIC18F2XK20 TYPICAL PRI_RUN IDD (HS + PLL)
16
14
64 MHz
(16 MHz Input)
12
IDD (mA)
10
40 MHz
(10 MHz Input)
8
6
4
16 MHz
(4 MHz Input)
2
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-14:
PIC18F4XK20/PIC18F2XK20 MAXIMUM PRI_RUN IDD (HS + PLL)
20
18
64 MHz
(16 MHz Input)
16
14
IDD (mA)
12
40 MHz
(10 MHz Input)
10
8
6
16 MHz
(4 MHz Input)
4
2
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 409
PIC18F2XK20/4XK20
FIGURE 27-15:
PIC18F4XK20/PIC18F2XK20 TYPICAL PRI_IDLE IDD (EC)
7
6
64 MHz
5
IDD (mA)
4
40 MHz
3
2
20 MHz
16 MHz
1
10 MHz
4 MHz
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-16:
PIC18F4XK20/PIC18F2XK20 MAXIMUM PRI_IDLE IDD (EC)
9
8
64 MHz
7
IDD (mA)
6
5
40 MHz
4
3
20 MHz
16 MHz
2
10 MHz
1
4 MHz
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
DS41303G-page 410
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-17:
PIC18F4XK20/PIC18F2XK20 IWDT – Delta IPD for Watchdog Timer, -40°C to
+125°C
4.0
3.5
Max.
3.0
IPD (uA)
2.5
2.0
1.5
Typ.
1.0
0.5
0.0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-18:
PIC18F4XK20/PIC18F2XK20 IBOR and IHLVD – Delta IPD for Brownout Reset
and High/Low Voltage Detect, -40°C to +125°C
70
Max. BOR
60
IPD (uA)
50
40
Max. HLVD
30
Typ. BOR
20
Typ. HLVD
10
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 411
PIC18F2XK20/4XK20
FIGURE 27-19:
PIC18F4XK20/PIC18F2XK20 IOCSB – Delta IPD for Low Power Timer1 Oscillator
3.5
Max.
3.0
-40°C to +85°C
IPD (uA)
2.5
2.0
1.5
1.0
Typ. 85°C
Typ. 25°C
0.5
0.0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-20:
PIC18F4XK20/PIC18F2XK20 IOCSB – Typical Delta IPD for High Power Timer1
Oscillator
20
85°C
18
25°C
IPD (uA)
16
-40°C
14
12
10
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
DS41303G-page 412
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-21:
PIC18F4XK20/PIC18F2XK20 IOCSB – Maximum Delta IPD for High Power Timer1
Oscillator
42
85°C
40
38
IPD (uA)
25°C
36
34
-40°C
32
30
28
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-22:
PIC18F4XK20/PIC18F2XK20 ICVREF – Delta IPD for Comparator Voltage
Reference, -40°C to +125°C
80
70
Max.
60
40
IPD
(uA)
50
Typ.
30
20
10
0
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 413
PIC18F2XK20/4XK20
FIGURE 27-23:
PIC18F4XK20/PIC18F2XK20 IAD – Typical Delta IDD for ADC, 25°C to +125°C
(Run Mode, ADC on, but not converting)
340
320
125°C
300
85°C
IDD
(uA)
280
25°C
260
240
220
200
180
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-24:
PIC18F4XK20/PIC18F2XK20 IAD – Maximum Delta IDD for ADC, 25°C to +125°C
(Run Mode, ADC on, but not converting)
440
125°C
420
85°C
400
380
25°C
IDD (uA)
360
340
320
300
280
260
240
220
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
DS41303G-page 414
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-25:
PIC18F4XK20/PIC18F2XK20 ICOMP – Typical Delta IPD for Comparator in Low
Power Mode, -40°C to +125°C
7.0
125°C
6.5
85°C
IPD (uA)
6.0
5.5
25°C
5.0
4.5
-40°C
4.0
3.5
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-26:
PIC18F4XK20/PIC18F2XK20 ICOMP – Maximum Delta IPD for Comparator in
Low Power Mode, -40°C to +125°C
16
125°C
15
85°C
IPD (uA)
14
25°C
13
12
-40°C
11
10
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 415
PIC18F2XK20/4XK20
FIGURE 27-27:
PIC18F4XK20/PIC18F2XK20 ICOMP – Typical Delta IPD for Comparator in High
Power Mode, -40°C to +125°C
55
50
125°C
85°C
IPD (uA)
45
25°C
40
-40°C
35
30
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-28:
PIC18F4XK20/PIC18F2XK20 ICOMP – Maximum Delta IPD for Comparator in
High Power Mode, -40°C to +125°C
95
125°C
90
85°C
IPD (uA)
85
80
25°C
75
70
-40°C
65
60
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
DS41303G-page 416
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-29:
PIC18F4XK20/PIC18F2XK20 COMPARATOR OFFSET (LOW POWER, VDD = 1.8V)
70
60
-40°C 3 sigma
Abs. Offset (mV)
50
25°C 3 sigma
85°C 3 sigma
40
°
125
30
sigm
C3
a
Typical
20
10
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
VREF (V)
FIGURE 27-30:
PIC18F4XK20/PIC18F2XK20 COMPARATOR OFFSET (LOW POWER, VDD = 3.6V)
70
-40°C 3 sigma
60
25
a
sig
m
a
°C
C
3
sig
85
m
a
°C
3
40
30
12
5°
Abs. Offset (mV)
50
igm
3s
Typical
20
10
0
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
3.6
VREF (V)
 2010 Microchip Technology Inc.
DS41303G-page 417
PIC18F2XK20/4XK20
FIGURE 27-31:
PIC18F4XK20/PIC18F2XK20 COMPARATOR OFFSET (HIGH POWER, VDD = 1.8V)
45
40
-40°C 3 sigma
35
Abs. Offset (mV)
25°C 3 sigma
30
85°C
25
ma
3 sig
igma
C3s
125°
20
Typical
15
10
5
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
VREF (V)
FIGURE 27-32:
PIC18F4XK20/PIC18F2XK20 COMPARATOR OFFSET (HIGH POWER, VDD = 3.6V)
45
-40°C 3 sigma
40
25°C 3 sigma
Abs. Offset (mV)
35
30
C3
85°
25
5°C
12
a
sigm
igm
3s
a
20
Typical
15
10
5
0
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
3.6
VREF (V)
DS41303G-page 418
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-33:
PIC18F4XK20/PIC18F2XK20 TYPICAL FIXED VOLTAGE REFERENCE
1.205
25°C
1.200
-40°C
85°C
FVR (V)
1.195
1.190
1.185
125°C
1.180
1.175
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-34:
PIC18F4XK20/PIC18F2XK20 TYPICAL FIXED VOLTAGE REFERENCE (MAX./
MIN. = 1.2V +/- 50MV FROM -40°C TO +85°C)
1.205
1.200
3.6V
2.0V
FVR (V)
1.195
1.190
1.8V
1.185
1.180
1.175
-40
-20
0
20
40
60
80
100
120
Temp. (°C)
 2010 Microchip Technology Inc.
DS41303G-page 419
PIC18F2XK20/4XK20
FIGURE 27-35:
PIC18F4XK20/PIC18F2XK20 TTL BUFFER VIH
1.8
Min.
1.6
1.4
VIH (V)
1.2
-40°C
25°C
1.0
85°C
125°C
0.8
0.6
0.4
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
VDD (V)
FIGURE 27-36:
PIC18F4XK20/PIC18F2XK20 SCHMITT TRIGGER BUFFER VIH
3.0
2.8
Min.
2.6
2.4
VIH (V)
2.2
-40°C
25°C
125°C
85°C
2.0
1.8
1.6
1.4
1.2
1.0
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
VDD (V)
DS41303G-page 420
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-37:
PIC18F4XK20/PIC18F2XK20 TTL BUFFER VIL
1.2
-40°C
1.0
25°C
85°C
125°C
VIL (V)
0.8
0.6
Max.
0.4
0.2
0.0
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.4
3.6
VDD (V)
FIGURE 27-38:
PIC18F4XK20/PIC18F2XK20 SCHMITT TRIGGER BUFFER VIL
1.6
-40°C
25°C
85°C 125°C
1.4
1.2
VIL (V)
1.0
0.8
Max.
0.6
0.4
0.2
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
VDD (V)
 2010 Microchip Technology Inc.
DS41303G-page 421
PIC18F2XK20/4XK20
FIGURE 27-39:
PIC18F4XK20/PIC18F2XK20 VOH VS. IOH (-40°C TO +125°C)
3.6
3
2.4
VOH (V)
Typ. 3.0V
1.8
Typ. 3.6V
Min. 3.0V
1.2
Typ. 1.8V
0.6
Min. 3.6V
Min. 1.8V
0
0
5
10
15
20
25
IOH (mA)
FIGURE 27-40:
PIC18F4XK20/PIC18F2XK20 VOL VS. IOL (-40°C TO +125°C)
1.8
Max. 1.8V
Max. 3.0V
1.5
Max. 3.6V
VOL (V)
1.2
0.9
1.8V
0.6
3.0V
3.6V
0.3
0
0
5
10
15
20
25
IOL (mA)
DS41303G-page 422
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-41:
PIC18F4XK20/PIC18F2XK20 PIN INPUT LEAKAGE
1000
RA2 Max.
RA3 Max.
I/O Ports Max.
Input Leakage (nA)
100
RA2 Typ.
RA3 Typ.
I/O Ports Typ.
10
1
25
30
35
40
45
50
55
60
65
70
75
80
85
Temp. (°C)
 2010 Microchip Technology Inc.
DS41303G-page 423
PIC18F2XK20/4XK20
FIGURE 27-42:
PIC18F4XK20/PIC18F2XK20 TYPICAL HF-INTOSC FREQUENCY
16.08
25°C
Frequency (MHz)
16.00
15.92
85°C
-40°C
15.84
15.76
125°C
15.68
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-43:
PIC18F4XK20/PIC18F2XK20 TYPICAL HF-INTOSC FREQUENCY
16.80
16.64
16.48
Max
Frequency (MHz)
16.32
16.16
16.00
3.0V
15.84
Min
15.68
15.52
15.36
15.20
-40
-20
0
20
40
60
80
100
120
Temp. (°C)
DS41303G-page 424
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
FIGURE 27-44:
PIC18F4XK20/PIC18F2XK20 TYPICAL LF-INTOSC FREQUENCY (MAX./MIN. =
31.25 KHZ +/-15%)
33.25
Frequency (kHz)
32.25
31.25
25°C
-40°C
30.25
85°C
29.25
125°C
28.25
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
VDD (V)
FIGURE 27-45:
PIC18F4XK20/PIC18F2XK20 TYPICAL LF-INTOSC FREQUENCY (MAX./MIN. =
31.25 KHZ +/-15%)
33.25
32.25
Frequency (kHz)
1.8V
31.25
2.5V
3.6V
3.0V
30.25
29.25
28.25
-40
-20
0
20
40
60
80
100
120
Temp. (°C)
 2010 Microchip Technology Inc.
DS41303G-page 425
PIC18F2XK20/4XK20
NOTES:
DS41303G-page 426
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
28.0
PACKAGING INFORMATION
28.1
Package Marking Information
28-Lead PDIP
Example
PIC18F25K20-E/SP
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXX
YYWWNNN
28-Lead SOIC (7.50 mm)
0810017
Example
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
YYWWNNN
40-Lead PDIP
PIC18F25K20-E/SO e3
0810017
Example
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
YYWWNNN
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
e3
PIC18F45K20-E/P e3
0810017
Customer-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC designator ( e3 )
can be found on the outer packaging for this package.
In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
 2010 Microchip Technology Inc.
DS41303G-page 427
PIC18F2XK20/4XK20
Package Marking Information (Continued)
28-Lead SSOP
XXXXXXXXXXXXXXX
XXXXXXXXXXXXXXX
XXXXXXXXXXXXXXX
YYWWNNN
28-Lead QFN
XXXXXXXX
XXXXXXXX
YYWWNNN
44-Lead QFN
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
44-Lead TQFP
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
28-Lead UQFN
XXXXX
XXXXXX
XXXXXX
YWWNNN
DS41303G-page 428
Example
PIC18F25K20-E/SS
e3
0810017
Example
18F24K20
-E/ML e3
0810017
Example
PIC18F45K20
-E/ML e3
0810017
Example
PIC18F44K20
-E/PT e3
0810017
Example
PIC18
F23K20
-E/MV e3
810017
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
28.2
Package Details
The following sections give the technical details of the packages.
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 2010 Microchip Technology Inc.
DS41303G-page 429
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DS41303G-page 430
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
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 2010 Microchip Technology Inc.
DS41303G-page 431
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 2010 Microchip Technology Inc.
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 2010 Microchip Technology Inc.
DS41303G-page 433
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DS41303G-page 434
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
 2010 Microchip Technology Inc.
DS41303G-page 435
PIC18F2XK20/4XK20
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
DS41303G-page 436
 2010 Microchip Technology Inc.
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 2010 Microchip Technology Inc.
DS41303G-page 437
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 2010 Microchip Technology Inc.
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DS41303G-page 440
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
APPENDIX A:
REVISION HISTORY
Revision E (04/2009)
Original data sheet for PIC18F2XK20/4XK20 devices.
Revised data sheet title; Revised Power-Managed
Modes, Peripheral Highlights, and Analog Features;
Revised 26.2, DC Char. table.
Revision B (03/2007)
Revision F (09/2009)
Added
part
numbers
PIC18F26K20
and
PIC18F46K20; Replaced Development Support
Section; Replaced Package Drawings.
Changed the values in the “Extreme Low-Power
Management with nanoWatt XLP” section; Added new
Note 2 to Pin Diagrams; Updated Electrical
Characteristics section; Added charts to the DS
Characteristics section; Removed Preliminary label;
Added UQFN to Pin Diagrams; Added the 28-pin
UQFN to Table 3-1; Updated MSSP section (Register
17-3; changing SSPADD<6:0> to SSPADD<7:0>);
Updated the Development Support section deleting
section 25.7; Added the 28-Lead UQFN package
marking diagrams and the 28-Lead Plastic Ultra Thin
Quad Flat, No Lead Package (MV) - 4X4X0.5 mm Body
(UQFN) package to Packaging Information section;
Other minor corrections.
Revision A (07/2006)
Revision C (10/2007)
Revised Table 1, DIL Pins 34 and 35; Table 2, Pins 22
and 24; Table 1-2, Pins RB1 and RB3; Table 1-3, Pins
RB1 and RB3; Revised Sections 4.3, 4.4, 4.4.1, 4.4.2,
4.4.4; Revised Table 4-3, Note 2; Revised Table 6-1;
Revise Section 7.8: Revised Section 9.2; Revised
Examples 10-1 and 10-2; Revised Table 10-3, Pins
RB1 and RB3; Revised Sections 12.2 through 12.5;
Revised Register 16-1, bit 3-0; Revised Sections 16.1,
16.2, 16.4.4; Revised Register 16-2, bit 6-4; Revised
Table 16-2, Note 2; Revised Register 17-1, bit 6;
Revised Register 17-3; Revised Table 17-4; Revised
Register 19-1, added Note 2; Revised Register 20-3,
bits 5 and 4; Revised Register 23-4, bit 1; Revised Register 23-12, bit 7-5; Revised Section 23.3; Revised Section 24.1.1, instruction set descriptions; Revised
Section 26.0, voltage on MCLR; Revised DC Characteristics 26.2, 26.3, 26.4 26.5, 26.6, 26.7, 26.8 and
26.10; Revised Tables 26-1, 26-6, 26-7, 26-9, 26-23.
Revision G (01/2010)
Updated Figure 9-1; Reviewed Section 26 (Electrical
Characteristics); Added Figures 27-29, 27-30, 27-31
and 27-32 to Section 27 (DC and AC Characteristics
Graphs and Tables); Reviewed Product Identification
System section.
Revision D (08/2008)
Update to Peripheral Highlights (USART module);
Deleted Section 2.2.6 (Oscillator Transitions); Revised
Sections 2.5.3, 2.9; Added Section 2.9.3 (Clock Switch
Timing); Deleted Section 2.10.4 (Clock Switching Timing); Replaced BAUDCTL with BAUDCON throughout;
Revised Table 5-2 (PLUSW0, PLUSW1, PLUSW2);
Add Note 1 to Table 7-1 (EEADRH); Revised Section
6.4.4 and Register 16-2 (FLT0 pin); Revised Registers
17-2 and 17-5 (SSPEN); Revised Register 17-6
(SEN); Added new paragraph after Figure 18-2;
Revised Note, Section 18.1.1; Deleted Note, Section
18.1.2; Added new Note 2, Sections 18.1.2.9 and
18.1.2.10; Revised Note 1, Section 18.3.1; Added
Section 18.3.2; Revised Section 18.3.5; Added new
Note 2, Sections 18.4.1.5, 18.4.1.10, 18.4.2.2,
18.4.2.4; Revised Register 21-1 (CVR); Revised Note
1, Registers 23-6, 23.8, 23-10, Table 23-3; Added new
Figure 26-1; Revised 26.2, 26.6, 26.7 (Note 3), 26.8,
26.9, 26.10; Revised Tables 26-1, 26-2, 26-3, 26-6, 267, 26-8, 26-25; Updated Package Drawings.
 2010 Microchip Technology Inc.
DS41303G-page 441
PIC18F2XK20/4XK20
APPENDIX B:
DEVICE
DIFFERENCES
The differences between the devices listed in this data
sheet are shown in Table B-1.
TABLE B-1:
DEVICE DIFFERENCES
Features
PIC18F23K20 PIC18F24K20 PIC18F25K20 PIC18F26K20 PIC18F43K20 PIC18F44K20 PIC18F45K20 PIC18F46K20
Program Memory
(Bytes)
8192
16384
32768
65536
8192
16384
32768
65536
Program Memory
(Instructions)
4096
8192
16384
32768
4096
8192
16384
32768
19
19
19
19
20
20
20
20
Interrupt Sources
I/O Ports
Ports A, B, C, Ports A, B, C, Ports A, B, C, Ports A, B, C,
(E)
(E)
(E)
(E)
Ports A, B, C, Ports A, B, C, Ports A, B, C, Ports A, B, C,
D, E
D, E
D, E
D, E
Capture/Compare/PWM
Modules
1
1
1
1
1
1
1
1
Enhanced
Capture/Compare/PWM
Modules
1
1
1
1
1
1
1
1
Parallel
Communications (PSP)
No
No
No
No
Yes
Yes
Yes
Yes
10-bit Analog-to-Digital
Module
11 input
channels
11 input
channels
11 input
channels
11 input
channels
14 input
channels
14 input
channels
14 input
channels
14 input
channels
28-pin PDIP
28-pin SOIC
28-pin SSOP
28-pin QFN
28-pin UQFN
28-pin PDIP
28-pin SOIC
28-pin SSOP
28-pin QFN
28-pin PDIP
28-pin SOIC
28-pin SSOP
28-pin QFN
28-pin PDIP
28-pin SOIC
28-pin SSOP
28-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
Packages
DS41303G-page 442
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
INDEX
A
B
A/D
Bank Select Register (BSR) .............................................. 71
Baud Rate Generator ...................................................... 221
BAUDCON Register ........................................................ 248
BC .................................................................................... 323
BCF ................................................................................. 324
BF .................................................................................... 225
BF Status Flag ................................................................. 225
Block Diagrams
ADC ......................................................................... 265
ADC Transfer Function ............................................ 276
Analog Input Model .......................................... 276, 286
Baud Rate Generator .............................................. 221
Capture Mode Operation ......................................... 146
CCP PWM ............................................................... 149
Clock Source ............................................................. 27
Comparator 1 ........................................................... 280
Comparator 2 ........................................................... 280
Comparator Voltage Reference ............................... 290
Compare Mode Operation ....................................... 147
Crystal Operation ....................................................... 31
EUSART Receive .................................................... 238
EUSART Transmit ................................................... 237
External POR Circuit (Slow VDD Power-up) .............. 53
External RC Mode ..................................................... 32
Fail-Safe Clock Monitor (FSCM) ................................ 40
Generic I/O Port ....................................................... 121
High/Low-Voltage Detect with External Input .......... 294
Interrupt Logic .......................................................... 108
MSSP (I2C Master Mode) ........................................ 219
MSSP (I2C Mode) .................................................... 202
MSSP (SPI Mode) ................................................... 193
On-Chip Reset Circuit ................................................ 51
PIC18F2XK20 ............................................................ 14
PIC18F4XK20 ............................................................ 15
PLL (HS Mode) .......................................................... 35
PORTD and PORTE (Parallel Slave Port) ............... 139
PWM (Enhanced) .................................................... 175
Reads from Flash Program Memory ......................... 93
Resonator Operation ................................................. 31
Table Read Operation ............................................... 89
Table Write Operation ............................................... 90
Table Writes to Flash Program Memory .................... 95
Timer0 in 16-Bit Mode ............................................. 157
Timer0 in 8-Bit Mode ............................................... 156
Timer1 ..................................................................... 160
Timer1 (16-Bit Read/Write Mode) ............................ 160
Timer2 ..................................................................... 168
Timer3 ..................................................................... 170
Timer3 (16-Bit Read/Write Mode) ............................ 171
Voltage Reference Output Buffer Example ............. 291
Watchdog Timer ...................................................... 308
BN .................................................................................... 324
BNC ................................................................................. 325
BNN ................................................................................. 325
BNOV .............................................................................. 326
BNZ ................................................................................. 326
BOR. See Brown-out Reset.
BOV ................................................................................. 329
BRA ................................................................................. 327
Break Character (12-bit) Transmit and Receive .............. 256
BRG. See Baud Rate Generator.
Brown-out Reset (BOR) ..................................................... 54
Analog Port Pins, Configuring .................................. 277
Associated Registers ............................................... 277
Conversions ............................................................. 268
Converter Characteristics ........................................ 401
Discharge ................................................................. 269
Selecting and Configuring Acquisition Time ............ 266
Special Event Trigger (ECCP) ................................. 174
Absolute Maximum Ratings ............................................. 369
AC (Timing) Characteristics ............................................. 383
Load Conditions for Device Timing Specifications ... 384
Parameter Symbology ............................................. 383
Temperature and Voltage Specifications ................. 384
Timing Conditions .................................................... 384
AC Characteristics
Internal RC Accuracy ............................................... 386
Access Bank
Mapping with Indexed Literal Offset Mode ................. 87
ACKSTAT ........................................................................ 225
ACKSTAT Status Flag ..................................................... 225
ADC ................................................................................. 265
Acquisition Requirements ........................................ 275
Block Diagram .......................................................... 265
Calculating Acquisition Time .................................... 275
Channel Selection .................................................... 266
Configuration ............................................................ 266
Conversion Clock ..................................................... 266
Conversion Procedure ............................................. 270
Internal Sampling Switch (RSS) IMPEDANCE ............. 275
Interrupts .................................................................. 267
Operation ................................................................. 268
Operation During Sleep ........................................... 269
Port Configuration .................................................... 266
Power Management ................................................. 269
Reference Voltage (VREF) ........................................ 266
Result Formatting ..................................................... 267
Source Impedance ................................................... 275
Special Event Trigger ............................................... 269
Starting an A/D Conversion ..................................... 267
ADCON0 Register ............................................................ 271
ADCON1 Register ............................................................ 272
ADCON2 Register ............................................................ 273
ADDFSR .......................................................................... 358
ADDLW ............................................................................ 321
ADDULNK ........................................................................ 358
ADDWF ............................................................................ 321
ADDWFC ......................................................................... 322
ADRESH Register (ADFM = 0) ........................................ 274
ADRESH Register (ADFM = 1) ........................................ 274
ADRESL Register (ADFM = 0) ......................................... 274
ADRESL Register (ADFM = 1) ......................................... 274
Analog Input Connection Considerations ......................... 286
Analog-to-Digital Converter. See ADC
ANDLW ............................................................................ 322
ANDWF ............................................................................ 323
ANSEL (PORT Analog Control) ....................................... 136
ANSEL Register ............................................................... 136
ANSELH Register ............................................................ 137
Assembler
MPASM Assembler .................................................. 366
 2010 Microchip Technology Inc.
DS41303G-page 443
PIC18F2XK20/4XK20
Detecting .................................................................... 54
Disabling in Sleep Mode ............................................ 54
Minimun Enable Time ................................................ 54
Software Enabled ....................................................... 54
BSF .................................................................................. 327
BTFSC ............................................................................. 328
BTFSS .............................................................................. 328
BTG .................................................................................. 329
BZ ..................................................................................... 330
C
C Compilers
MPLAB C18 ............................................................. 366
CALL ................................................................................ 330
CALLW ............................................................................. 359
Capture (CCP Module) ..................................................... 145
Associated Registers ............................................... 148
CCP Pin Configuration ............................................. 145
CCPRxH:CCPRxL Registers ................................... 145
Prescaler .................................................................. 145
Software Interrupt .................................................... 145
Timer1/Timer3 Mode Selection ................................ 145
Capture (ECCP Module) .................................................. 174
Capture/Compare/PWM (CCP) ........................................ 143
Capture Mode. See Capture.
CCP Mode and Timer Resources ............................ 144
CCPRxH Register .................................................... 144
CCPRxL Register ..................................................... 144
Compare Mode. See Compare.
Interaction of Two CCP Modules ............................. 144
Module Configuration ............................................... 144
PWM Mode .............................................................. 149
Duty Cycle ........................................................ 150
Effects of Reset ................................................ 152
Example PWM Frequencies & Resolutions
Fosc=20 MHZ .......................................... 151
Fosc=40 MHZ .......................................... 151
Fosc=8 MHZ ............................................ 151
Operation in Sleep Mode ................................. 152
Setup for Operation .......................................... 152
System Clock Frequency Changes .................. 152
PWM Period ............................................................. 150
Setup for PWM Operation ........................................ 152
CCP1CON Register ......................................................... 173
CCP2CON Register ......................................................... 143
Clock Accuracy with Asynchronous Operation ................ 246
Clock Sources
Associated registers ................................................... 41
External Modes .......................................................... 30
EC ...................................................................... 30
HS ...................................................................... 31
LP ....................................................................... 31
OST .................................................................... 30
RC ...................................................................... 32
XT ...................................................................... 31
Internal Modes ........................................................... 32
Frequency Selection .......................................... 34
HFINTOSC ......................................................... 32
INTOSC ............................................................. 32
INTOSCIO .......................................................... 32
LFINTOSC ......................................................... 34
Selecting the 31 kHz Source ...................................... 28
Selection Using OSCCON Register ........................... 28
Clock Switching .................................................................. 37
CLRF ................................................................................ 331
CLRWDT .......................................................................... 331
DS41303G-page 444
CM1CON0 Register ......................................................... 284
CM2CON0 Register ......................................................... 285
CM2CON1 Register ......................................................... 287
Code Examples
16 x 16 Signed Multiply Routine .............................. 106
16 x 16 Unsigned Multiply Routine .......................... 106
8 x 8 Signed Multiply Routine .................................. 105
8 x 8 Unsigned Multiply Routine .............................. 105
A/D Conversion ........................................................ 270
Changing Between Capture Prescalers ................... 145
Clearing RAM Using Indirect Addressing .................. 83
Computed GOTO Using an Offset Value ................... 68
Data EEPROM Read ............................................... 101
Data EEPROM Refresh Routine .............................. 102
Data EEPROM Write ............................................... 101
Erasing a Flash Program Memory Row ..................... 94
Fast Register Stack ................................................... 68
Implementing a Timer1 Real-Time Clock ................ 164
Initializing PORTA .................................................... 121
Initializing PORTB .................................................... 124
Initializing PORTC ................................................... 127
Initializing PORTD ................................................... 130
Initializing PORTE .................................................... 133
Loading the SSPBUF (SSPSR) Register ................. 196
Reading a Flash Program Memory Word .................. 93
Saving Status, WREG and BSR Registers
in RAM ............................................................. 119
Writing to Flash Program Memory ....................... 96–97
Code Protection ............................................................... 299
COMF .............................................................................. 332
Comparator
Associated Registers ............................................... 288
Operation ................................................................. 279
Operation During Sleep ........................................... 283
Response Time ........................................................ 281
Comparator Module ......................................................... 279
C1 Output State Versus Input Conditions ................ 281
Comparator Specifications ............................................... 381
Comparator Voltage Reference (CVREF)
Associated Registers ............................................... 292
Effects of a Reset ............................................ 283, 289
Operation During Sleep ........................................... 289
Overview .................................................................. 289
Comparator Voltage Reference (CVREF)
Response Time ........................................................ 281
Comparators
Effects of a Reset .................................................... 283
Compare (CCP Module) .................................................. 147
Associated Registers ............................................... 148
CCPRx Register ...................................................... 147
Pin Configuration ..................................................... 147
Software Interrupt .................................................... 147
Special Event Trigger ...................................... 147, 172
Timer1/Timer3 Mode Selection ................................ 147
Compare (ECCP Module) ................................................ 174
Special Event Trigger .............................................. 174
Computed GOTO ............................................................... 68
CONFIG1H Register ........................................................ 301
CONFIG2H Register ........................................................ 302
CONFIG2L Register ........................................................ 302
CONFIG3H Register ........................................................ 303
CONFIG4L Register ........................................................ 303
CONFIG5H Register ........................................................ 304
CONFIG5L Register ........................................................ 304
CONFIG6H Register ........................................................ 305
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
CONFIG6L Register ......................................................... 305
CONFIG7H Register ........................................................ 306
CONFIG7L Register ......................................................... 306
Configuration Bits ............................................................. 300
Configuration Register Protection .................................... 313
Context Saving During Interrupts ..................................... 119
CPFSEQ .......................................................................... 332
CPFSGT .......................................................................... 333
CPFSLT ........................................................................... 333
Customer Change Notification Service ............................ 453
Customer Notification Service .......................................... 453
Customer Support ............................................................ 453
CVREF Voltage Reference Specifications ........................ 381
D
Data Addressing Modes ..................................................... 83
Comparing Addressing Modes with the
Extended Instruction Set Enabled ..................... 86
Direct .......................................................................... 83
Indexed Literal Offset ................................................. 85
Instructions Affected .......................................... 85
Indirect ....................................................................... 83
Inherent and Literal .................................................... 83
Data EEPROM
Code Protection ....................................................... 313
Data EEPROM Memory ..................................................... 99
Associated Registers ............................................... 103
EEADR and EEADRH Registers ............................... 99
EECON1 and EECON2 Registers ............................. 99
Operation During Code-Protect ............................... 102
Protection Against Spurious Write ........................... 102
Reading .................................................................... 101
Using ........................................................................ 102
Write Verify .............................................................. 101
Writing ...................................................................... 101
Data Memory ..................................................................... 71
Access Bank .............................................................. 77
and the Extended Instruction Set ............................... 85
Bank Select Register (BSR) ....................................... 71
General Purpose Registers ........................................ 77
Map for PIC18F23K20/43K20 .................................... 72
Map for PIC18F24K20/44K20 .................................... 73
Map for PIC18F25K20/45K20 .............................. 74, 75
Special Function Registers ........................................ 77
DAW ................................................................................. 334
DC and AC Characteristics
Graphs and Tables .................................................. 403
DC Characteristics
Input/Output ............................................................. 377
Peripheral Supply Current ........................................ 376
Power-Down Current ............................................... 371
Primary Idle Supply Current ..................................... 374
Primary Run Supply Current .................................... 374
RC Idle Supply Current ............................................ 373
RC Run Supply Current ........................................... 372
Secondary Oscillator Supply Current ....................... 375
Supply Voltage ......................................................... 371
DCFSNZ .......................................................................... 335
DECF ............................................................................... 334
DECFSZ ........................................................................... 335
Development Support ...................................................... 365
Device Differences ........................................................... 442
Device Overview ................................................................ 11
Details on Individual Family Members ....................... 12
New Core Features .................................................... 11
Other Special Features .............................................. 12
 2010 Microchip Technology Inc.
Device Reset Timers ......................................................... 55
PLL Lock Time-out .................................................... 55
Power-up Timer (PWRT) ........................................... 55
Time-out Sequence ................................................... 55
DEVID1 Register ............................................................. 307
DEVID2 Register ............................................................. 307
Direct Addressing .............................................................. 84
E
ECCPAS Register ............................................................ 183
EECON1 Register ...................................................... 91, 100
Effect on Standard PIC Instructions ................................. 362
Effects of Power Managed Modes on Various
Clock Sources ........................................................... 36
Effects of Reset
PWM mode .............................................................. 152
Electrical Characteristics ................................................. 369
Enhanced Capture/Compare/PWM (ECCP) .................... 173
Associated Registers ............................................... 191
Capture and Compare Modes ................................. 174
Capture Mode. See Capture (ECCP Module).
Enhanced PWM Mode ............................................. 175
Auto-Restart .................................................... 184
Auto-shutdown ................................................ 183
Direction Change in Full-Bridge
Output Mode ............................................ 181
Full-Bridge Application ..................................... 179
Full-Bridge Mode ............................................. 179
Half-Bridge Application .................................... 178
Half-Bridge Application Examples ................... 185
Half-Bridge Mode ............................................. 178
Output Relationships (Active-High and
Active-Low) .............................................. 176
Output Relationships Diagram ......................... 177
Programmable Dead Band Delay .................... 185
Shoot-through Current ..................................... 185
Start-up Considerations ................................... 182
Outputs and Configuration ....................................... 174
Standard PWM Mode .............................................. 174
Timer Resources ..................................................... 174
Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) ............................. 237
Errata ................................................................................. 10
EUSART .......................................................................... 237
Asynchronous Mode ................................................ 239
12-bit Break Transmit and Receive ................. 256
Associated Registers, Receive ........................ 245
Associated Registers, Transmit ....................... 241
Auto-Wake-up on Break .................................. 254
Baud Rate Generator (BRG) ........................... 249
Clock Accuracy ................................................ 246
Receiver .......................................................... 242
Setting up 9-bit Mode with Address Detect ..... 244
Transmitter ...................................................... 239
Baud Rate Generator (BRG)
Associated Registers ....................................... 249
Auto Baud Rate Detect .................................... 253
Baud Rate Error, Calculating ........................... 249
Baud Rates, Asynchronous Modes ................. 250
Formulas .......................................................... 249
High Baud Rate Select (BRGH Bit) ................. 249
Clock polarity
Synchronous Mode .......................................... 257
Data polarity
Asychronous Receive ...................................... 242
Asychronous Transmit ..................................... 239
DS41303G-page 445
PIC18F2XK20/4XK20
Synchronous Mode .......................................... 257
Interrupts
Asychronous Receive ...................................... 243
Asychronous Transmit ..................................... 239
Synchronous Master Mode .............................. 257, 262
Associated Registers, Receive ........................ 261
Associated Registers, Transmit ............... 259, 262
Reception ......................................................... 260
Transmission .................................................... 257
Synchronous Slave Mode
Associated Registers, Receive ........................ 263
Reception ......................................................... 263
Transmission .................................................... 262
Extended Instruction Set
ADDFSR .................................................................. 358
ADDULNK ................................................................ 358
and Using MPLAB Tools .......................................... 364
CALLW ..................................................................... 359
Considerations for Use ............................................ 362
MOVSF .................................................................... 359
MOVSS .................................................................... 360
PUSHL ..................................................................... 360
SUBFSR .................................................................. 361
SUBULNK ................................................................ 361
Syntax ...................................................................... 357
F
Fail-Safe Clock Monitor .............................................. 40, 299
Fail-Safe Condition Clearing ...................................... 40
Fail-Safe Detection .................................................... 40
Fail-Safe Operation .................................................... 40
Reset or Wake-up from Sleep .................................... 40
Fast Register Stack ............................................................ 68
Firmware Instructions ....................................................... 315
Flash Program Memory ...................................................... 89
Associated Registers ................................................. 97
Control Registers ....................................................... 90
EECON1 and EECON2 ..................................... 90
TABLAT (Table Latch) Register ......................... 92
TBLPTR (Table Pointer) Register ...................... 92
Erase Sequence ........................................................ 94
Erasing ....................................................................... 94
Operation During Code-Protect ................................. 97
Reading ...................................................................... 93
Table Pointer
Boundaries Based on Operation ........................ 92
Table Pointer Boundaries .......................................... 92
Table Reads and Table Writes .................................. 89
Write Sequence ......................................................... 95
Writing To ................................................................... 95
Protection Against Spurious Writes ................... 97
Unexpected Termination .................................... 97
Write Verify ........................................................ 97
G
General Call Address Support ......................................... 218
GOTO ............................................................................... 336
H
Hardware Multiplier .......................................................... 105
Introduction .............................................................. 105
Operation ................................................................. 105
Performance Comparison ........................................ 105
High/Low-Voltage Detect ................................................. 293
Applications .............................................................. 297
Associated Registers ............................................... 297
DS41303G-page 446
Characteristics ......................................................... 382
Current Consumption ............................................... 295
Effects of a Reset .................................................... 297
Operation ................................................................. 294
During Sleep .................................................... 297
Setup ....................................................................... 295
Start-up Time ........................................................... 295
Typical Application ................................................... 297
HLVD. See High/Low-Voltage Detect. ............................. 293
HLVDCON Register ......................................................... 293
I
I/O Ports ........................................................................... 121
I2C
Associated Registers ............................................... 235
I2C Mode (MSSP)
Acknowledge Sequence Timing .............................. 228
Baud Rate Generator .............................................. 221
Bus Collision
During a Repeated Start Condition .................. 232
During a Stop Condition .................................. 234
Clock Arbitration ...................................................... 222
Clock Stretching ....................................................... 214
10-Bit Slave Receive Mode (SEN = 1) ............ 214
10-Bit Slave Transmit Mode ............................ 214
7-Bit Slave Receive Mode (SEN = 1) .............. 214
7-Bit Slave Transmit Mode .............................. 214
Clock Synchronization and the CKP bit (SEN = 1) .. 215
Effects of a Reset .................................................... 229
General Call Address Support ................................. 218
I2C Clock Rate w/BRG ............................................. 221
Master Mode ............................................................ 219
Operation ......................................................... 220
Reception ........................................................ 225
Repeated Start Condition Timing .................... 224
Start Condition Timing ..................................... 223
Transmission ................................................... 225
Multi-Master Communication, Bus Collision
and Arbitration ................................................. 229
Multi-Master Mode ................................................... 229
Operation ................................................................. 207
Read/Write Bit Information (R/W Bit) ............... 207, 208
Registers ................................................................. 202
Serial Clock (RC3/SCK/SCL) ................................... 208
Slave Mode .............................................................. 207
Addressing ....................................................... 207
Reception ........................................................ 208
Transmission ................................................... 208
Sleep Operation ....................................................... 229
Stop Condition Timing ............................................. 228
ID Locations ............................................................. 299, 313
INCF ................................................................................ 336
INCFSZ ............................................................................ 337
In-Circuit Debugger .......................................................... 313
In-Circuit Serial Programming (ICSP) ...................... 299, 313
Indexed Literal Offset Addressing
and Standard PIC18 Instructions ............................. 362
Indexed Literal Offset Mode ............................................. 362
Indirect Addressing ............................................................ 84
INFSNZ ............................................................................ 337
Initialization Conditions for all Registers ...................... 59–62
Instruction Cycle ................................................................ 69
Clocking Scheme ....................................................... 69
Instruction Flow/Pipelining ................................................. 69
Instruction Set .................................................................. 315
ADDLW .................................................................... 321
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PIC18F2XK20/4XK20
ADDWF .................................................................... 321
ADDWF (Indexed Literal Offset Mode) .................... 363
ADDWFC ................................................................. 322
ANDLW .................................................................... 322
ANDWF .................................................................... 323
BC ............................................................................ 323
BCF .......................................................................... 324
BN ............................................................................ 324
BNC ......................................................................... 325
BNN ......................................................................... 325
BNOV ....................................................................... 326
BNZ .......................................................................... 326
BOV ......................................................................... 329
BRA .......................................................................... 327
BSF .......................................................................... 327
BSF (Indexed Literal Offset Mode) .......................... 363
BTFSC ..................................................................... 328
BTFSS ..................................................................... 328
BTG .......................................................................... 329
BZ ............................................................................ 330
CALL ........................................................................ 330
CLRF ........................................................................ 331
CLRWDT .................................................................. 331
COMF ...................................................................... 332
CPFSEQ .................................................................. 332
CPFSGT .................................................................. 333
CPFSLT ................................................................... 333
DAW ......................................................................... 334
DCFSNZ .................................................................. 335
DECF ....................................................................... 334
DECFSZ ................................................................... 335
Extended Instruction Set .......................................... 357
General Format ........................................................ 317
GOTO ...................................................................... 336
INCF ......................................................................... 336
INCFSZ .................................................................... 337
INFSNZ .................................................................... 337
IORLW ..................................................................... 338
IORWF ..................................................................... 338
LFSR ........................................................................ 339
MOVF ....................................................................... 339
MOVFF .................................................................... 340
MOVLB .................................................................... 340
MOVLW ................................................................... 341
MOVWF ................................................................... 341
MULLW .................................................................... 342
MULWF .................................................................... 342
NEGF ....................................................................... 343
NOP ......................................................................... 343
Opcode Field Descriptions ....................................... 316
POP ......................................................................... 344
PUSH ....................................................................... 344
RCALL ..................................................................... 345
RESET ..................................................................... 345
RETFIE .................................................................... 346
RETLW .................................................................... 346
RETURN .................................................................. 347
RLCF ........................................................................ 347
RLNCF ..................................................................... 348
RRCF ....................................................................... 348
RRNCF .................................................................... 349
SETF ........................................................................ 349
SETF (Indexed Literal Offset Mode) ........................ 363
SLEEP ..................................................................... 350
SUBFWB .................................................................. 350
 2010 Microchip Technology Inc.
SUBLW .................................................................... 351
SUBWF .................................................................... 351
SUBWFB ................................................................. 352
SWAPF .................................................................... 352
TBLRD ..................................................................... 353
TBLWT .................................................................... 354
TSTFSZ ................................................................... 355
XORLW ................................................................... 355
XORWF ................................................................... 356
INTCON Register ............................................................. 109
INTCON Registers ................................................... 109–111
INTCON2 Register ........................................................... 110
INTCON3 Register ........................................................... 111
Inter-Integrated Circuit. See I2C.
Internal Oscillator Block
HFINTOSC Frequency Drift ....................................... 34
PLL in HFINTOSC Modes ......................................... 35
Internal RC Oscillator
Use with WDT .......................................................... 308
Internal Sampling Switch (RSS) IMPEDANCE ..................... 275
Internet Address .............................................................. 453
Interrupt Sources ............................................................. 299
ADC ......................................................................... 267
Capture Complete (CCP) ........................................ 145
Compare Complete (CCP) ...................................... 147
Interrupt-on-Change (RB7:RB4) .............................. 124
INTn Pin ................................................................... 119
PORTB, Interrupt-on-Change .................................. 119
TMR0 ....................................................................... 119
TMR0 Overflow ........................................................ 157
TMR1 Overflow ........................................................ 159
TMR3 Overflow ................................................ 169, 171
Interrupts ......................................................................... 107
IORLW ............................................................................. 338
IORWF ............................................................................. 338
IPR Registers ................................................................... 116
IPR1 Register .................................................................. 116
IPR2 Register .................................................................. 117
L
LFSR ............................................................................... 339
Low-Voltage ICSP Programming. See Single-Supply
ICSP Programming
M
Master Clear (MCLR) ......................................................... 53
Master Synchronous Serial Port (MSSP). See MSSP.
Memory Organization ........................................................ 65
Data Memory ............................................................. 71
Program Memory ....................................................... 65
Microchip Internet Web Site ............................................. 453
MOVF .............................................................................. 339
MOVFF ............................................................................ 340
MOVLB ............................................................................ 340
MOVLW ........................................................................... 341
MOVSF ............................................................................ 359
MOVSS ............................................................................ 360
MOVWF ........................................................................... 341
MPLAB ASM30 Assembler, Linker, Librarian .................. 366
MPLAB Integrated Development Environment
Software .................................................................. 365
MPLAB PM3 Device Programmer ................................... 368
MPLAB REAL ICE In-Circuit Emulator System ............... 367
MPLINK Object Linker/MPLIB Object Librarian ............... 366
MSSP
ACK Pulse ....................................................... 207, 208
DS41303G-page 447
PIC18F2XK20/4XK20
Control Registers (general) ...................................... 193
I2C Mode. See I2C Mode.
Module Overview ..................................................... 193
SPI Master/Slave Connection .................................. 197
SPI Mode. See SPI Mode.
SSPBUF Register .................................................... 198
SSPSR Register ...................................................... 198
MULLW ............................................................................ 342
MULWF ............................................................................ 342
N
NEGF ............................................................................... 343
NOP ................................................................................. 343
O
OSCCON Register ............................................................. 29
Oscillator Configuration
EC .............................................................................. 27
ECIO .......................................................................... 27
HS .............................................................................. 27
HSPLL ........................................................................ 27
INTOSC ..................................................................... 27
INTOSCIO .................................................................. 27
LP ............................................................................... 27
RC .............................................................................. 27
RCIO .......................................................................... 27
XT .............................................................................. 27
Oscillator Module ............................................................... 27
HFINTOSC ................................................................. 27
LFINTOSC ................................................................. 27
Oscillator Selection .......................................................... 299
Oscillator Start-up Timer (OST) ................................... 36, 55
Oscillator Switching
Fail-Safe Clock Monitor .............................................. 40
Two-Speed Clock Start-up ......................................... 38
Oscillator, Timer1 ..................................................... 159, 171
Oscillator, Timer3 ............................................................. 169
OSCTUNE Register ........................................................... 33
P
P1A/P1B/P1C/P1D.See Enhanced Capture/
Compare/PWM (ECCP) ........................................... 175
Packaging Information ..................................................... 427
Marking .................................................................... 427
Parallel Slave Port (PSP) ......................................... 130, 139
Associated Registers ............................................... 141
CS (Chip Select) ...................................................... 139
PORTD .................................................................... 139
RD (Read Input) ....................................................... 139
Select (PSPMODE Bit) .................................... 130, 139
WR (Write Input) ...................................................... 139
PIE Registers ................................................................... 114
PIE1 Register ................................................................... 114
PIE2 Register ................................................................... 115
Pin Functions
MCLR/VPP/RE3 .................................................... 16, 20
OSC1/CLKI/RA7 .................................................. 16, 20
OSC2/CLKO/RA6 ................................................ 16, 20
RA0/AN0/C12IN0- ................................................ 17, 21
RA1/AN1/C12IN0- ...................................................... 21
RA1/AN1/C12IN1- ...................................................... 17
RA2/AN2/VREF-/CVREF/C2IN+ ............................. 17, 21
RA3/AN3/VREF+/C1IN+ ........................................ 17, 21
RA4/T0CKI/C1OUT .............................................. 17, 21
RA5/AN4/SS/HLVDIN/C2OUT ............................. 17, 21
RB0/INT0/FLT0/AN12 .......................................... 18, 22
DS41303G-page 448
RB1/INT1/AN10/C12IN3- ........................................... 22
RB1/INT1/AN10/P1C/C12IN3- ................................... 18
RB2/INT2/AN8 ........................................................... 22
RB2/INT2/AN8/P1B ................................................... 18
RB3/AN9/CCP2/C12IN2- ..................................... 18, 22
RB4/KBI0/AN11 ......................................................... 22
RB4/KBI0/AN11/P1D ................................................. 18
RB5/KBI1/PGM .................................................... 18, 22
RB6/KBI2/PGC .................................................... 18, 22
RB7/KBI3/PGD .................................................... 18, 22
RC0/T1OSO/T13CKI ........................................... 19, 23
RC1/T1OSI/CCP2 ................................................ 19, 23
RC2/CCP1/P1A ................................................... 19, 23
RC3/SCK/SCL ..................................................... 19, 23
RC4/SDI/SDA ...................................................... 19, 23
RC5/SDO ............................................................. 19, 23
RC6/TX/CK .......................................................... 19, 23
RC7/RX/DT .......................................................... 19, 23
RD0/PSP0 ................................................................. 24
RD1/PSP1 ................................................................. 24
RD2/PSP2 ................................................................. 24
RD3/PSP3 ................................................................. 24
RD4/PSP4 ................................................................. 24
RD5/PSP5/P1B ......................................................... 24
RD6/PSP6/P1C ......................................................... 24
RD7/PSP7/P1D ......................................................... 24
RE0/RD/AN5 .............................................................. 25
RE1/WR/AN6 ............................................................. 25
RE2/CS/AN7 .............................................................. 25
VDD ...................................................................... 19, 25
VSS ...................................................................... 19, 25
Pinout I/O Descriptions
PIC18F2XK20 ............................................................ 16
PIC18F4XK20 ............................................................ 20
PIR Registers ................................................................... 112
PIR1 Register .................................................................. 112
PIR2 Register .................................................................. 113
PLL Frequency Multiplier ................................................... 35
HSPLL Oscillator Mode ............................................. 35
POP ................................................................................. 344
POR. See Power-on Reset.
PORTA
Associated Registers ............................................... 123
LATA Register ......................................................... 121
PORTA Register ...................................................... 121
TRISA Register ........................................................ 121
PORTB
Associated Registers ............................................... 126
LATB Register ......................................................... 124
PORTB Register ...................................................... 124
TRISB Register ........................................................ 124
PORTC
Associated Registers ............................................... 129
LATC Register ......................................................... 127
PORTC Register ...................................................... 127
RC3/SCK/SCL Pin ................................................... 208
TRISC Register ........................................................ 127
PORTD
Associated Registers ............................................... 132
LATD Register ......................................................... 130
Parallel Slave Port (PSP) Function .......................... 130
PORTD Register ...................................................... 130
TRISD Register ........................................................ 130
PORTE
Associated Registers ............................................... 135
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PIC18F2XK20/4XK20
LATE Register .......................................................... 133
PORTE Register ...................................................... 133
PSP Mode Select (PSPMODE Bit) .......................... 130
TRISE Register ........................................................ 133
Power Managed Modes ..................................................... 43
and A/D Operation ................................................... 269
and PWM Operation ................................................ 190
and SPI Operation ................................................... 201
Clock Transitions and Status Indicators ..................... 44
Effects on Clock Sources ........................................... 36
Entering ...................................................................... 43
Exiting Idle and Sleep Modes .................................... 48
by Interrupt ......................................................... 48
by Reset ............................................................. 48
by WDT Time-out ............................................... 48
Without a Start-up Delay .................................... 49
Idle Modes ................................................................. 45
PRI_IDLE ........................................................... 47
RC_IDLE ............................................................ 48
SEC_IDLE ......................................................... 47
Multiple Sleep Functions ............................................ 44
Run Modes ................................................................. 44
PRI_RUN ........................................................... 44
SEC_RUN .......................................................... 44
Selecting .................................................................... 43
Sleep Mode ................................................................ 45
Summary (table) ........................................................ 43
Power-on Reset (POR) ...................................................... 53
Power-up Timer (PWRT) ........................................... 55
Time-out Sequence .................................................... 55
Power-up Delays ................................................................ 36
Power-up Timer (PWRT) ................................................... 36
Prescaler, Timer0 ............................................................. 157
PRI_IDLE Mode ................................................................. 47
PRI_RUN Mode ................................................................. 44
Program Counter ............................................................... 66
PCL, PCH and PCU Registers ................................... 66
PCLATH and PCLATU Registers .............................. 66
Program Memory
and Extended Instruction Set ..................................... 87
Code Protection ....................................................... 311
Instructions ................................................................. 70
Two-Word .......................................................... 70
Interrupt Vector .......................................................... 65
Look-up Tables .......................................................... 68
Map and Stack (diagram) ........................................... 65
Reset Vector .............................................................. 65
Program Verification and Code Protection ....................... 310
Associated Registers ............................................... 310
Programming, Device Instructions ................................... 315
PSP. See Parallel Slave Port.
PSTRCON Register ......................................................... 187
Pulse Steering .................................................................. 187
PUSH ............................................................................... 344
PUSH and POP Instructions .............................................. 67
PUSHL ............................................................................. 360
PWM (CCP Module)
Associated Registers ............................................... 153
PWM (ECCP Module)
Effects of a Reset ..................................................... 190
Operation in Power Managed Modes ...................... 190
Operation with Fail-Safe Clock Monitor ................... 190
Pulse Steering .......................................................... 187
Steering Synchronization ......................................... 189
PWM Mode. See Enhanced Capture/Compare/PWM ..... 175
 2010 Microchip Technology Inc.
PWM1CON Register ........................................................ 186
R
RAM. See Data Memory.
RC_IDLE Mode .................................................................. 48
RCALL ............................................................................. 345
RCON Register .......................................................... 52, 118
Bit Status During Initialization .................................... 58
RCREG ............................................................................ 244
RCSTA Register .............................................................. 247
Reader Response ............................................................ 454
Register
RCREG Register ..................................................... 253
Register File ....................................................................... 77
Register File Summary ................................................ 79–81
Registers
ADCON0 (ADC Control 0) ....................................... 271
ADCON1 (ADC Control 1) ....................................... 272
ADCON2 (ADC Control 2) ....................................... 273
ADRESH (ADC Result High) with ADFM = 0) ......... 274
ADRESH (ADC Result High) with ADFM = 1) ......... 274
ADRESL (ADC Result Low) with ADFM = 0) ........... 274
ADRESL (ADC Result Low) with ADFM = 1) ........... 274
ANSEL (Analog Select 1) ........................................ 136
ANSEL (PORT Analog Control) ............................... 136
ANSELH (Analog Select 2) ...................................... 137
ANSELH (PORT Analog Control) ............................ 137
BAUDCON (Baud Rate Control) .............................. 248
BAUDCON (EUSART Baud Rate Control) .............. 248
CCP1CON (Enhanced Capture/Compare/PWM
Control) ............................................................ 173
CCP2CON (Standard Capture/Compare/PWM
Control) ............................................................ 143
CM1CON0 (C1 Control) .......................................... 284
CM2CON0 (C2 Control) .......................................... 285
CM2CON1 (C2 Control) .......................................... 287
CONFIG1H (Configuration 1 High) .......................... 301
CONFIG2H (Configuration 2 High) .......................... 302
CONFIG2L (Configuration 2 Low) ........................... 302
CONFIG3H (Configuration 3 High) .......................... 303
CONFIG4L (Configuration 4 Low) ........................... 303
CONFIG5H (Configuration 5 High) .......................... 304
CONFIG5L (Configuration 5 Low) ........................... 304
CONFIG6H (Configuration 6 High) .......................... 305
CONFIG6L (Configuration 6 Low) ........................... 305
CONFIG7H (Configuration 7 High) .......................... 306
CONFIG7L (Configuration 7 Low) ........................... 306
CVRCON (Comparator Voltage Reference
Control CVRCON Register .............................. 291
CVRCON2 (Comparator Voltage Reference
Control 2) CVRCON2 Register ........................ 292
DEVID1 (Device ID 1) .............................................. 307
DEVID2 (Device ID 2) .............................................. 307
ECCPAS (Enhanced CCP Auto-shutdown
Control) ............................................................ 183
EECON1 (Data EEPROM Control 1) ................. 91, 100
HLVDCON (High/Low-Voltage Detect Control) ....... 293
INTCON (Interrupt Control) ..................................... 109
INTCON2 (Interrupt Control 2) ................................ 110
INTCON3 (Interrupt Control 3) ................................ 111
IPR1 (Peripheral Interrupt Priority 1) ....................... 116
IPR2 (Peripheral Interrupt Priority 2) ....................... 117
OSCCON (Oscillator Control) .................................... 29
OSCTUNE (Oscillator Tuning) ................................... 33
PIE1 (Peripheral Interrupt Enable 1) ....................... 114
PIE2 (Peripheral Interrupt Enable 2) ....................... 115
DS41303G-page 449
PIC18F2XK20/4XK20
PIR1 (Peripheral Interrupt Request 1) ..................... 112
PIR2 (Peripheral Interrupt Request 2) ..................... 113
PSTRCON (Pulse Steering Control) ........................ 187
PWM1CON (Enhanced PWM Control) .................... 186
RCON (Reset Control) ....................................... 52, 118
RCON (Reset control) .............................................. 118
RCSTA (Receive Status and Control) ...................... 247
SLRCON (PORT Slew Rate Control) ....................... 138
SSPADD (MSSP Address and Baud Rate,
SPI Mode) ........................................................ 203
SSPCON1 (MSSP Control 1, I2C Mode) ................. 205
SSPCON1 (MSSP Control 1, SPI Mode) ................. 195
SSPCON2 (MSSP Control 2, I2C Mode) ................. 206
SSPMSK (SSP Mask) .............................................. 213
SSPSTAT (MSSP Status, SPI Mode) .............. 194, 204
STATUS ..................................................................... 82
STKPTR (Stack Pointer) ............................................ 67
T0CON (Timer0 Control) .......................................... 155
T1CON (Timer1 Control) .......................................... 159
T2CON (Timer2 Control) .......................................... 167
T3CON (Timer3 Control) .......................................... 169
TRISE (PORTE/PSP Control) .................................. 134
TXSTA (Transmit Status and Control) ..................... 246
WDTCON (Watchdog Timer Control) ....................... 309
RESET ............................................................................. 345
Reset State of Registers .................................................... 58
Resets ........................................................................ 51, 299
Brown-out Reset (BOR) ........................................... 299
Oscillator Start-up Timer (OST) ............................... 299
Power-on Reset (POR) ............................................ 299
Power-up Timer (PWRT) ......................................... 299
RETFIE ............................................................................ 346
RETLW ............................................................................. 346
RETURN .......................................................................... 347
Return Address Stack ........................................................ 66
Return Stack Pointer (STKPTR) ........................................ 67
Revision History ............................................................... 441
RLCF ................................................................................ 347
RLNCF ............................................................................. 348
RRCF ............................................................................... 348
RRNCF ............................................................................. 349
S
SCK .................................................................................. 193
SDI ................................................................................... 193
SDO ................................................................................. 193
SEC_IDLE Mode ................................................................ 47
SEC_RUN Mode ................................................................ 44
Serial Clock, SCK ............................................................. 193
Serial Data In (SDI) .......................................................... 193
Serial Data Out (SDO) ..................................................... 193
Serial Peripheral Interface. See SPI Mode.
SETF ................................................................................ 349
Shoot-through Current ..................................................... 185
Single-Supply ICSP Programming.
Slave Select (SS) ............................................................. 193
Slave Select Synchronization ........................................... 199
SLEEP .............................................................................. 350
Sleep
OSC1 and OSC2 Pin States ...................................... 36
Sleep Mode ........................................................................ 45
Slew Rate ......................................................................... 138
SLRCON Register ............................................................ 138
Software Simulator (MPLAB SIM) .................................... 367
SPBRG ............................................................................. 249
SPBRGH .......................................................................... 249
DS41303G-page 450
Special Event Trigger ...................................................... 269
Special Event Trigger. See Compare (ECCP Mode).
Special Event Trigger. See Compare (ECCP Module).
Special Features of the CPU ........................................... 299
Special Function Registers ................................................ 77
Map ............................................................................ 78
SPI Mode (MSSP)
Associated Registers ............................................... 201
Bus Mode Compatibility ........................................... 201
Effects of a Reset .................................................... 201
Enabling SPI I/O ...................................................... 197
Master Mode ............................................................ 198
Master/Slave Connection ......................................... 197
Operation ................................................................. 196
Operation in Power Managed Modes ...................... 201
Serial Clock .............................................................. 193
Serial Data In ........................................................... 193
Serial Data Out ........................................................ 193
Slave Mode .............................................................. 199
Slave Select ............................................................. 193
Slave Select Synchronization .................................. 199
SPI Clock ................................................................. 198
Typical Connection .................................................. 197
SS .................................................................................... 193
SSPADD Register ............................................................ 203
SSPCON1 Register ................................................. 195, 205
SSPCON2 Register ......................................................... 206
SSPMSK Register ........................................................... 213
SSPOV ............................................................................ 225
SSPOV Status Flag ......................................................... 225
SSPSTAT Register .................................................. 194, 204
R/W Bit ............................................................ 207, 208
Stack Full/Underflow Resets .............................................. 68
Standard Instructions ....................................................... 315
STATUS Register .............................................................. 82
STKPTR Register .............................................................. 67
SUBFSR .......................................................................... 361
SUBFWB ......................................................................... 350
SUBLW ............................................................................ 351
SUBULNK ........................................................................ 361
SUBWF ............................................................................ 351
SUBWFB ......................................................................... 352
SWAPF ............................................................................ 352
T
T0CON Register .............................................................. 155
T1CON Register .............................................................. 159
T2CON Register .............................................................. 167
T3CON Register .............................................................. 169
Table Pointer Operations (table) ........................................ 92
Table Reads/Table Writes ................................................. 68
TBLRD ............................................................................. 353
TBLWT ............................................................................. 354
Time-out in Various Situations (table) ................................ 55
Timer0 .............................................................................. 155
Associated Registers ............................................... 157
Operation ................................................................. 156
Overflow Interrupt .................................................... 157
Prescaler ................................................................. 157
Prescaler Assignment (PSA Bit) .............................. 157
Prescaler Select (T0PS2:T0PS0 Bits) ..................... 157
Prescaler. See Prescaler, Timer0.
Reads and Writes in 16-Bit Mode ............................ 156
Source Edge Select (T0SE Bit) ............................... 156
Source Select (T0CS Bit) ......................................... 156
Switching Prescaler Assignment ............................. 157
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PIC18F2XK20/4XK20
Timer1 .............................................................................. 159
16-Bit Read/Write Mode ........................................... 162
Associated Registers ............................................... 165
Asynchronous Counter Mode .................................. 161
Reading and Writing ........................................ 161
Interrupt .................................................................... 163
Operation ................................................................. 160
Oscillator .......................................................... 159, 162
Oscillator Layout Considerations ............................. 163
Overflow Interrupt .................................................... 159
Prescaler .................................................................. 161
Resetting, Using the CCP Special Event Trigger ..... 163
Special Event Trigger (ECCP) ................................. 174
TMR1H Register ...................................................... 159
TMR1L Register ....................................................... 159
Use as a Real-Time Clock ....................................... 164
Timer2 .............................................................................. 167
Associated Registers ............................................... 168
Interrupt .................................................................... 168
Operation ................................................................. 167
Output ...................................................................... 168
Timer3 .............................................................................. 169
16-Bit Read/Write Mode ........................................... 171
Associated Registers ............................................... 172
Operation ................................................................. 170
Oscillator .......................................................... 169, 171
Overflow Interrupt ............................................ 169, 171
Special Event Trigger (CCP) .................................... 172
TMR3H Register ...................................................... 169
TMR3L Register ....................................................... 169
Timing Diagrams
A/D Conversion ........................................................ 402
Acknowledge Sequence .......................................... 228
Asynchronous Reception ......................................... 245
Asynchronous Transmission .................................... 240
Asynchronous Transmission (Back to Back) ........... 241
Auto Wake-up Bit (WUE) During Normal
Operation ......................................................... 255
Auto Wake-up Bit (WUE) During Sleep ................... 255
Automatic Baud Rate Calculator .............................. 254
Baud Rate Generator with Clock Arbitration ............ 222
BRG Reset Due to SDA Arbitration During
Start Condition ................................................. 231
Brown-out Reset (BOR) ........................................... 388
Bus Collision During a Repeated Start Condition
(Case 1) ........................................................... 232
Bus Collision During a Repeated Start Condition
(Case 2) ........................................................... 233
Bus Collision During a Start Condition (SCL = 0) .... 231
Bus Collision During a Stop Condition (Case 1) ...... 234
Bus Collision During a Stop Condition (Case 2) ...... 234
Bus Collision During Start Condition (SDA only) ..... 230
Bus Collision for Transmit and Acknowledge ........... 229
Capture/Compare/PWM (CCP) ................................ 390
CLKO and I/O .......................................................... 387
Clock Synchronization ............................................. 215
Clock/Instruction Cycle .............................................. 69
Comparator Output .................................................. 279
Example SPI Master Mode (CKE = 0) ..................... 392
Example SPI Master Mode (CKE = 1) ..................... 393
Example SPI Slave Mode (CKE = 0) ....................... 394
Example SPI Slave Mode (CKE = 1) ....................... 395
External Clock (All Modes except PLL) .................... 384
Fail-Safe Clock Monitor (FSCM) ................................ 41
First Start Bit Timing ................................................ 223
 2010 Microchip Technology Inc.
Full-Bridge PWM Output .......................................... 180
Half-Bridge PWM Output ................................. 178, 185
High/Low-Voltage Detect Characteristics ................ 382
High/Low-Voltage Detect Operation
(VDIRMAG = 0) ............................................... 295
High/Low-Voltage Detect Operation
(VDIRMAG = 1) ............................................... 296
I2C Bus Data ............................................................ 396
I2C Bus Start/Stop Bits ............................................ 396
I2C Master Mode (7 or 10-Bit Transmission) ........... 226
I2C Master Mode (7-Bit Reception) ......................... 227
I2C Slave Mode (10-Bit Reception, SEN = 0) .......... 211
I2C Slave Mode (10-Bit Reception, SEN = 1) .......... 217
I2C Slave Mode (10-Bit Transmission) .................... 212
I2C Slave Mode (7-bit Reception, SEN = 0) ............ 209
I2C Slave Mode (7-Bit Reception, SEN = 1) ............ 216
I2C Slave Mode (7-Bit Transmission) ...................... 210
I2C Slave Mode General Call Address
Sequence (7 or 10-Bit Address Mode) ............ 218
I2C Stop Condition Receive or Transmit Mode ........ 228
Internal Oscillator Switch Timing ............................... 39
Master SSP I2C Bus Data ....................................... 398
Master SSP I2C Bus Start/Stop Bits ........................ 398
Parallel Slave Port (PIC18F4XK20) ......................... 391
Parallel Slave Port (PSP) Read ............................... 140
Parallel Slave Port (PSP) Write ............................... 140
PWM Auto-shutdown
Auto-restart Enabled ........................................ 184
Firmware Restart ............................................. 184
PWM Direction Change ........................................... 181
PWM Direction Change at Near 100% Duty Cycle .. 182
PWM Output (Active-High) ...................................... 176
PWM Output (Active-Low) ....................................... 177
Repeat Start Condition ............................................ 224
Reset, Watchdog Timer (WDT), Oscillator Start-up
Timer (OST), Power-up Timer (PWRT) .......... 388
Send Break Character Sequence ............................ 256
Slave Synchronization ............................................. 199
Slow Rise Time (MCLR Tied to VDD,
VDD Rise > TPWRT) ............................................ 57
SPI Mode (Master Mode) ........................................ 198
SPI Mode (Slave Mode, CKE = 0) ........................... 200
SPI Mode (Slave Mode, CKE = 1) ........................... 200
Synchronous Reception (Master Mode, SREN) ...... 261
Synchronous Transmission ..................................... 258
Synchronous Transmission (Through TXEN) .......... 258
Time-out Sequence on POR w/PLL Enabled
(MCLR Tied to VDD) .......................................... 57
Time-out Sequence on Power-up (MCLR
Not Tied to VDD, Case 1) ................................... 56
Time-out Sequence on Power-up (MCLR
Not Tied to VDD, Case 2) ................................... 56
Time-out Sequence on Power-up (MCLR
Tied to VDD, VDD Rise < TPWRT) ....................... 56
Timer0 and Timer1 External Clock .......................... 389
Timer1 Incrementing Edge ...................................... 161
Transition for Entry to Sleep Mode ............................ 46
Transition for Wake from Sleep (HSPLL) .................. 46
Transition Timing for Entry to Idle Mode .................... 47
Transition Timing for Wake from Idle to
Run Mode .......................................................... 47
USART Synchronous Receive (Master/Slave) ........ 400
USART Synchronous Transmission
(Master/Slave) ................................................. 400
Timing Diagrams and Specifications ............................... 384
DS41303G-page 451
PIC18F2XK20/4XK20
A/D Conversion Requirements ................................ 402
Capture/Compare/PWM Requirements ................... 390
CLKO and I/O Requirements ................................... 387
Example SPI Mode Requirements
(Master Mode, CKE = 0) .................................. 392
(Master Mode, CKE = 1) .................................. 393
(Slave Mode, CKE = 0) .................................... 394
(Slave Mode, CKE = 1) .................................... 395
External Clock Requirements .................................. 385
I2C Bus Data Requirements (Slave Mode) .............. 397
I2C Bus Start/Stop Bits Requirements
(Slave Mode) .................................................... 396
Master SSP I2C Bus Data Requirements ................ 399
Master SSP I2C Bus Start/Stop Bits
Requirements ................................................... 398
Parallel Slave Port Requirements (PIC18F4X20) .... 391
PLL Clock ................................................................. 386
Reset, Watchdog Timer, Oscillator Start-up Timer,
Power-up Timer and Brown-out Reset
Requirements ................................................... 388
Timer0 and Timer1 External Clock Requirements ... 389
USART Synchronous Receive Requirements ......... 400
USART Synchronous Transmission
Requirements ................................................... 400
Top-of-Stack Access .......................................................... 66
TRISE Register ................................................................ 134
PSPMODE Bit .......................................................... 130
TSTFSZ ............................................................................ 355
Two-Speed Clock Start-up Mode ....................................... 38
Two-Speed Start-up ......................................................... 299
Two-Word Instructions
Example Cases .......................................................... 70
TXREG ............................................................................. 239
TXSTA Register ............................................................... 246
BRGH Bit ................................................................. 249
V
Voltage Reference (VR)
Specifications ........................................................... 381
Voltage Reference. See Comparator Voltage
Reference (CVREF)
Voltage References
Fixed Voltage Reference (FVR) ............................... 290
VR Stabilization ........................................................ 290
VREF. SEE ADC Reference Voltage
W
Wake-up on Break ........................................................... 254
Watchdog Timer (WDT) ........................................... 299, 308
Associated Registers ............................................... 309
Control Register ....................................................... 309
Programming Considerations .................................. 308
WCOL ...................................................... 223, 224, 225, 228
WCOL Status Flag ................................... 223, 224, 225, 228
WDTCON Register ........................................................... 309
WWW Address ................................................................. 453
WWW, On-Line Support ..................................................... 10
X
XORLW ............................................................................ 355
XORWF ............................................................................ 356
DS41303G-page 452
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
THE MICROCHIP WEB SITE
CUSTOMER SUPPORT
Microchip provides online support via our WWW site at
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Users of Microchip products can receive assistance
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•
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To register, access the Microchip web site at
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 2010 Microchip Technology Inc.
DS41303G-page 453
PIC18F2XK20/4XK20
READER RESPONSE
It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation
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Device: PIC18F2XK20/4XK20
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Literature Number: DS41303G
Questions:
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2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
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DS41303G-page 454
 2010 Microchip Technology Inc.
PIC18F2XK20/4XK20
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
X
/XX
XXX
Device
Temperature
Range
Package
Pattern
Examples:
a)
b)
Device:
PIC18F23K20(1), PIC18F24K20(1), PIC18F25K20(1),
PIC18F26K20(1), PIC18F43K20(1), PIC18F44K20(1),
PIC18F45K20(1), PIC18F46K20(1)
Temperature
Range:
E
I
Package:
ML
MV
P
PT
SO
SP
SS
Pattern:
= -40C to +125C
= -40C to +85C
=
=
=
=
=
=
=
c)
d)
PIC18F45K20-E/P 301 = Extended temp.,
PDIP package, QTP pattern #301.
PIC18F23K20-I/SO = Industrial temp., SOIC
package.
PIC18F44K20-E/P = Extended temp., PDIP
package.
PIC18F46K20T-I/TP = Industrial temp., TQFP
package, tape and reel.
(Extended)
(Industrial)
QFN
UQFN
PDIP
TQFP (Thin Quad Flatpack)
SOIC
Skinny Plastic DIP
SSOP
Note 1:
T
= Part number appended with T
indicates tape and reel. P and SP
package options not available in tape
and reel.
QTP, SQTP, Code or Special Requirements
(blank otherwise)
 2010 Microchip Technology Inc.
DS41303G-page 455
WORLDWIDE SALES AND SERVICE
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Austria - Wels
Tel: 43-7242-2244-39
Fax: 43-7242-2244-393
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Toronto
Mississauga, Ontario,
Canada
Tel: 905-673-0699
Fax: 905-673-6509
Australia - Sydney
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
China - Beijing
Tel: 86-10-8528-2100
Fax: 86-10-8528-2104
China - Chengdu
Tel: 86-28-8665-5511
Fax: 86-28-8665-7889
Korea - Daegu
Tel: 82-53-744-4301
Fax: 82-53-744-4302
China - Chongqing
Tel: 86-23-8980-9588
Fax: 86-23-8980-9500
Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
China - Hong Kong SAR
Tel: 852-2401-1200
Fax: 852-2401-3431
Malaysia - Kuala Lumpur
Tel: 60-3-6201-9857
Fax: 60-3-6201-9859
China - Nanjing
Tel: 86-25-8473-2460
Fax: 86-25-8473-2470
Malaysia - Penang
Tel: 60-4-227-8870
Fax: 60-4-227-4068
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Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
Taiwan - Hsin Chu
Tel: 886-3-6578-300
Fax: 886-3-6578-370
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-536-4803
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
China - Xian
Tel: 86-29-8833-7252
Fax: 86-29-8833-7256
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
China - Xiamen
Tel: 86-592-2388138
Fax: 86-592-2388130
China - Zhuhai
Tel: 86-756-3210040
Fax: 86-756-3210049
01/05/10
DS41303G-page 456
 2010 Microchip Technology Inc.