MICROCHIP PIC18F2520

PIC18F2420/2520/4420/4520
Data Sheet
28/40/44-Pin Enhanced Flash
Microcontrollers with 10-Bit A/D
and nanoWatt Technology
© 2008 Microchip Technology Inc.
DS39631E
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and may be superseded by updates.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
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OTHERWISE, RELATED TO THE INFORMATION,
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Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro,
PICSTART, rfPIC, SmartShunt and UNI/O are registered
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
FilterLab, Linear Active Thermistor, MXDEV, MXLAB,
SEEVAL, SmartSensor 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, In-Circuit Serial
Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB
Certified logo, MPLIB, MPLINK, mTouch, PICkit, PICDEM,
PICDEM.net, PICtail, PIC32 logo, PowerCal, PowerInfo,
PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Total
Endurance, 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.
© 2008, 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.
DS39631E-page ii
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
28/40/44-Pin Enhanced Flash Microcontrollers with
10-Bit A/D and nanoWatt Technology
Power Management Features:
Peripheral Highlights (Continued):
•
•
•
•
•
•
•
•
•
•
• Master Synchronous Serial Port (MSSP) module
Supporting 3-Wire SPI (all 4 modes) and I2C™
Master and Slave modes
• Enhanced Addressable USART module:
- Supports RS-485, RS-232 and LIN/J2602
- RS-232 operation using internal oscillator
block (no external crystal required)
- Auto-wake-up on Start bit
- Auto-Baud Detect
• 10-Bit, up to 13-Channel Analog-to-Digital (A/D)
Converter module:
- Auto-acquisition capability
- Conversion available during Sleep
• Dual Analog Comparators with Input Multiplexing
• Programmable 16-Level High/Low-Voltage
Detection (HLVD) module:
- Supports interrupt on High/Low-Voltage Detection
Run: CPU on, Peripherals on
Idle: CPU off, Peripherals on
Sleep: CPU off, Peripherals off
Ultra Low 50nA Input Leakage
Run mode Currents Down to 11 μA Typical
Idle mode Currents Down to 2.5 μA Typical
Sleep mode Current Down to 100 nA Typical
Timer1 Oscillator: 900 nA, 32 kHz, 2V
Watchdog Timer: 1.4 μA, 2V Typical
Two-Speed Oscillator Start-up
Flexible Oscillator Structure:
• Four Crystal modes, up to 40 MHz
• 4x Phase Lock Loop (PLL) – Available for Crystal
and Internal Oscillators
• Two External RC modes, up to 4 MHz
• Two External Clock modes, up to 40 MHz
• Internal Oscillator Block:
- Fast wake from Sleep and Idle, 1 μs typical
- 8 use-selectable frequencies, from 31 kHz to
8 MHz
- Provides a complete range of clock speeds
from 31 kHz to 32 MHz when used with PLL
- User-tunable to compensate for frequency drift
• Secondary Oscillator using Timer1 @ 32 kHz
• Fail-Safe Clock Monitor:
- Allows for safe shutdown if peripheral clock stops
Special Microcontroller Features:
• C Compiler Optimized Architecture:
- Optional extended instruction set designed to
optimize re-entrant code
• 100,000 Erase/Write Cycle Enhanced Flash
Program Memory Typical
• 1,000,000 Erase/Write Cycle Data EEPROM
Memory Typical
• Flash/Data EEPROM Retention: 100 Years Typical
• Self-Programmable under Software Control
• Priority Levels for Interrupts
• 8 x 8 Single-Cycle Hardware Multiplier
• Extended Watchdog Timer (WDT):
- Programmable period from 4 ms to 131s
• Single-Supply 5V In-Circuit Serial
Programming™ (ICSP™) via Two Pins
• In-Circuit Debug (ICD) via Two Pins
• Wide Operating Voltage Range: 2.0V to 5.5V
• Programmable Brown-out Reset (BOR) with
Software Enable Option
Peripheral Highlights:
•
•
•
•
High-Current Sink/Source 25 mA/25 mA
Three Programmable External Interrupts
Four Input Change Interrupts
Up to 2 Capture/Compare/PWM (CCP) modules,
one with Auto-Shutdown (28-pin devices)
• Enhanced Capture/Compare/PWM (ECCP)
module (40/44-pin devices only):
- One, two or four PWM outputs
- Selectable polarity
- Programmable dead time
- Auto-shutdown and auto-restart
Program Memory
Device
Data Memory
Flash # Single-Word SRAM EEPROM
(bytes) Instructions (bytes) (bytes)
I/O
10-Bit
A/D (ch)
CCP/
ECCP
(PWM)
MSSP
SPI
Master
I2C™
EUSART
-
Comp.
Timers
8/16-Bit
PIC18F2420
16K
8192
768
256
25
10
2/0
Y
Y
1
2
1/3
PIC18F2520
32K
16384
1536
256
25
10
2/0
Y
Y
1
2
1/3
PIC18F4420
16K
8192
768
256
36
13
1/1
Y
Y
1
2
1/3
PIC18F4520
32K
16384
1536
256
36
13
1/1
Y
Y
1
2
1/3
© 2008 Microchip Technology Inc.
DS39631E-page 1
PIC18F2420/2520/4420/4520
Pin Diagrams
28-Pin SPDIP, SOIC
PIC18F2420
PIC18F2520
1
2
3
4
5
6
7
8
9
10
11
12
13
14
RA1/AN1
RA0/AN0
28-Pin QFN
28
27
26
25
24
23
22
21
20
19
18
17
16
15
RB7/KBI3/PGD
RB6//KBI2/PGC
RB5/KBI1/PGM
RB4/KBI0/AN11
RB3/AN9/CCP2(1)
RB2/INT2/AN8
RB1/INT1/AN10
RB0/INT0/FLT0/AN12
VDD
VSS
RC7/RX/DT
RC6/TX/CK
RC5/SDO
RC4/SDI/SDA
MCLR/VPP/RE3
RB7/KBI3/PGD
RB6/KBI2/PGC
RB5/KBI1/PGM
RB4KBI0/AN11
MCLR/VPP/RE3
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
VSS
OSC1/CLKI/RA7
OSC2/CLKO/RA6
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1
RC3/SCK/SCL
28 27 26 25 24 23 22
1
2
3
4
5
6
7
PIC18F2420
PIC18F2520
8 9 10 11 12 13 14
21
20
19
18
17
16
15
RB3/AN9/CCP2(1)
RB2/INT2/AN8
RB1/INT1/AN10
RB0/INT0/FLT0/AN12
VDD
VSS
RC7/RX/DT
40-Pin PDIP
MCLR/VPP/RE3
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
RE0/RD/AN5
RE1/WR/AN6
RE2/CS/AN7
VDD
VSS
OSC1/CLKI/RA7
OSC2/CLKO/RA6
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1/P1A
RC3/SCK/SCL
RD0/PSP0
RD1/PSP1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
PIC18F4420
PIC18F4520
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1
RC3/SCK/SCL
RC4/SDI/SDA
RC5/SDO
RC6/TX/CK
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
VSS
OSC1/CLKI/RA7
OSC2/CLKO/RA6
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
RB3/AN9/CCP2(1)
RB2/INT2/AN8
RB1/INT1/AN10
RB0/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
Note 1: RB3 is the alternate pin for CCP2 multiplexing.
DS39631E-page 2
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
33
32
31
30
29
28
27
26
25
24
23
PIC18F4420
PIC18F4520
12
13
14
15
16
17
18
19
20
21
22
1
2
3
4
5
6
7
8
9
10
11
NC
RC0/T1OSO/T13CKI
OSC2/CLKO/RA6
OSC1/CLKI/RA7
VSS
VDD
RE2/CS/AN7
RE1/WR/AN6
RE0/RD/AN5
RA5/AN4/SS/HLVDIN/C2OUT
RA4/T0CKI/C1OUT
44
43
42
41
40
39
38
37
36
35
34
1
2
3
4
5
6
7
8
9
10
11
PIC18F4420
PIC18F4520
33
32
31
30
29
28
27
26
25
24
23
OSC2/CLKO/RA6
OSC1/CLKI/RA7
VSS
VSS
VDD
VDD
RE2/CS/AN7
RE1/WR/AN6
RE0/RD/AN5
RA5/AN4/SS/HLVDIN/C2OUT
RA4/T0CKI/C1OUT
RB3/AN9/CCP2(1)
NC
RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
MCLR/VPP/RE3
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RC7/RX/DT
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
VSS
VDD
VDD
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
12
13
14
15
16
17
18
19
20
21
22
44-pin QFN
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)
RC0/T1OSO/T13CKI
NC
NC
RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
MCLR/VPP/RE3
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RC7/RX/DT
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
VSS
VDD
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
RB3/AN9/CCP2(1)
Note 1: RB3 is the alternate pin for CCP2 multiplexing.
© 2008 Microchip Technology Inc.
DS39631E-page 3
PIC18F2420/2520/4420/4520
Table of Contents
1.0 Device Overview .......................................................................................................................................................................... 7
2.0 Oscillator Configurations ............................................................................................................................................................ 23
3.0 Power-Managed Modes ............................................................................................................................................................. 33
4.0 Reset .......................................................................................................................................................................................... 41
5.0 Memory Organization ................................................................................................................................................................. 53
6.0 Flash Program Memory .............................................................................................................................................................. 73
7.0 Data EEPROM Memory ............................................................................................................................................................. 83
8.0 8 x 8 Hardware Multiplier............................................................................................................................................................ 89
9.0 Interrupts .................................................................................................................................................................................... 91
10.0 I/O Ports ................................................................................................................................................................................... 105
11.0 Timer0 Module ......................................................................................................................................................................... 123
12.0 Timer1 Module ......................................................................................................................................................................... 127
13.0 Timer2 Module ......................................................................................................................................................................... 133
14.0 Timer3 Module ......................................................................................................................................................................... 135
15.0 Capture/Compare/PWM (CCP) Modules ................................................................................................................................. 139
16.0 Enhanced Capture/Compare/PWM (ECCP) Module................................................................................................................ 147
17.0 Master Synchronous Serial Port (MSSP) Module .................................................................................................................... 161
18.0 Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) ............................................................... 201
19.0 10-Bit Analog-to-Digital Converter (A/D) Module ..................................................................................................................... 223
20.0 Comparator Module.................................................................................................................................................................. 233
21.0 Comparator Voltage Reference Module ................................................................................................................................... 239
22.0 High/Low-Voltage Detect (HLVD)............................................................................................................................................. 243
23.0 Special Features of the CPU .................................................................................................................................................... 249
24.0 Instruction Set Summary .......................................................................................................................................................... 267
25.0 Development Support............................................................................................................................................................... 317
26.0 Electrical Characteristics .......................................................................................................................................................... 321
27.0 DC and AC Characteristics Graphs and Tables ....................................................................................................................... 361
28.0 Packaging Information.............................................................................................................................................................. 383
Appendix A: Revision History............................................................................................................................................................. 395
Appendix B: Device Differences......................................................................................................................................................... 395
Appendix C: Migration from Mid-Range to Enhanced Devices .......................................................................................................... 396
Appendix D: Migration from High-End to Enhanced Devices............................................................................................................. 396
Index .................................................................................................................................................................................................. 397
The Microchip Web Site ..................................................................................................................................................................... 407
Customer Change Notification Service .............................................................................................................................................. 407
Customer Support .............................................................................................................................................................................. 407
Reader Response .............................................................................................................................................................................. 408
PIC18F2420/2520/4420/4520 Product Identification System ............................................................................................................ 409
DS39631E-page 4
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
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If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via
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welcome your feedback.
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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
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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, please specify which device, revision of silicon and data sheet (include literature number) you are
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© 2008 Microchip Technology Inc.
DS39631E-page 5
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 6
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
1.0
DEVICE OVERVIEW
This document contains device-specific information for
the following devices:
• PIC18F2420
• PIC18LF2420
• PIC18F2520
• PIC18LF2520
• PIC18F4420
• PIC18LF4420
• PIC18F4520
• PIC18LF4520
This family offers the advantages of all PIC18
microcontrollers – namely, high computational performance at an economical price – with the addition of
high-endurance, Enhanced Flash program memory.
On top of these features, the PIC18F2420/2520/4420/
4520 family introduces design enhancements that
make these microcontrollers a logical choice for many
high-performance, power sensitive applications.
1.1
1.1.1
New Core Features
nanoWatt TECHNOLOGY
All of the devices in the PIC18F2420/2520/4420/4520
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
power-saving 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.
© 2008 Microchip Technology Inc.
1.1.2
MULTIPLE OSCILLATOR OPTIONS
AND FEATURES
All of the devices in the PIC18F2420/2520/4420/4520
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 provides an
8 MHz clock and an INTRC source
(approximately 31 kHz), as well as a range of
6 user-selectable clock frequencies, between
125 kHz to 4 MHz, for a total of 8 clock
frequencies. 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 40 MHz. Used with the internal oscillator, the
PLL gives users a complete selection of clock
speeds, from 31 kHz to 32 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 internal oscillator. If a
clock failure occurs, the controller is switched to
the internal oscillator block, allowing for continued
low-speed 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.
DS39631E-page 7
PIC18F2420/2520/4420/4520
1.2
Other Special Features
• Memory Endurance: The Enhanced Flash cells
for both program memory and data EEPROM are
rated to last for many thousands of erase/write
cycles – up to 100,000 for program memory and
1,000,000 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 PIC18F2420/
2520/4420/4520 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, and auto-restart to reactivate outputs
once the condition has cleared.
• 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 EUSART 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, reducing code overhead.
• Extended Watchdog Timer (WDT): This
enhanced version incorporates a 16-bit prescaler,
allowing an extended time-out range that is stable
across operating voltage and temperature. See
Section 26.0 “Electrical Characteristics” for
time-out periods.
DS39631E-page 8
1.3
Details on Individual Family
Members
Devices in the PIC18F2420/2520/4420/4520 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.
5.
Flash program memory (16 Kbytes for
PIC18F2420/4420 devices and 32 Kbytes for
PIC18F2520/4520 devices).
A/D channels (10 for 28-pin devices, 13 for
40/44-pin devices).
I/O ports (3 bidirectional ports on 28-pin devices,
5 bidirectional ports on 40/44-pin devices).
CCP and Enhanced CCP implementation
(28-pin devices have 2 standard CCP
modules, 40/44-pin devices have one standard
CCP module and one ECCP module).
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 Table 1-2 and
Table 1-3.
Like all Microchip PIC18 devices, members of the
PIC18F2420/2520/4420/4520 family are available as
both standard and low-voltage devices. Standard
devices with Enhanced Flash memory, designated with
an “F” in the part number (such as PIC18F2420),
accommodate an operating VDD range of 4.2V to 5.5V.
Low-voltage parts, designated by “LF” (such as
PIC18LF2420), function over an extended VDD range
of 2.0V to 5.5V.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-1:
DEVICE FEATURES
Features
Operating Frequency
PIC18F2420
PIC18F2520
PIC18F4420
PIC18F4520
DC – 40 MHz
DC – 40 MHz
DC – 40 MHz
DC – 40 MHz
Program Memory (Bytes)
16384
32768
16384
32768
Program Memory
(Instructions)
8192
16384
8192
16384
Data Memory (Bytes)
768
1536
768
1536
Data EEPROM Memory (Bytes)
256
256
256
256
Interrupt Sources
19
19
20
20
Ports A, B, C, (E)
Ports A, B, C, (E)
Ports A, B, C, D, E
Ports A, B, C, D, E
I/O Ports
Timers
4
4
4
4
Capture/Compare/PWM Modules
2
2
1
1
Enhanced
Capture/Compare/PWM Modules
0
0
1
1
MSSP,
Enhanced USART
MSSP,
Enhanced USART
MSSP,
Enhanced USART
MSSP,
Enhanced USART
Serial Communications
Parallel Communications (PSP)
No
No
Yes
Yes
10-Bit Analog-to-Digital Module
10 Input Channels
10 Input Channels
13 Input Channels
13 Input Channels
Resets (and Delays)
Programmable
High/Low-Voltage Detect
Programmable Brown-out Reset
Instruction Set
Packages
© 2008 Microchip Technology Inc.
POR, BOR,
POR, BOR,
POR, BOR,
POR, BOR,
RESET Instruction,
RESET Instruction,
RESET Instruction,
RESET Instruction,
Stack Full, Stack
Stack Full, Stack
Stack Full, Stack
Stack Full, Stack
Underflow (PWRT, OST), Underflow (PWRT, OST), Underflow (PWRT, OST), Underflow (PWRT, OST),
MCLR (optional), WDT
MCLR (optional), WDT
MCLR (optional), WDT
MCLR (optional), WDT
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
28-Pin SPDIP
28-Pin SOIC
28-Pin QFN
28-Pin SPDIP
28-Pin SOIC
28-Pin QFN
40-Pin PDIP
44-Pin QFN
44-Pin TQFP
40-Pin PDIP
44-Pin QFN
44-Pin TQFP
DS39631E-page 9
PIC18F2420/2520/4420/4520
FIGURE 1-1:
PIC18F2420/2520 (28-PIN) BLOCK DIAGRAM
Data Bus<8>
Table Pointer<21>
Data Latch
8
8
inc/dec logic
PCLATU PCLATH
21
20
Address Latch
PCU PCH PCL
Program Counter
31-Level Stack
12
Data Address<12>
4
BSR
Address Latch
Program Memory
(16/32 Kbytes)
PORTA
Data Memory
( 3.9 Kbytes )
STKPTR
4
Access
Bank
12
FSR0
FSR1
FSR2
Data Latch
12
PORTB
8
inc/dec
logic
Table Latch
Address
Decode
ROM Latch
Instruction Bus <16>
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
OSC2/CLKO(3)/RA6
OSC1/CLKI(3)/RA7
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
RB3/AN9/CCP2(1)
RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
IR
Instruction
Decode and
Control
8
State Machine
Control Signals
PRODH PRODL
PORTC
3
8 x 8 Multiply
8
W
BITOP
8
Internal
Oscillator
Block
OSC1(3)
OSC2
(3)
T1OSI
INTRC
Oscillator
T1OSO
8 MHz
Oscillator
Power-up
Timer
Brown-out
Reset
Fail-Safe
Clock Monitor
Single-Supply
Programming
In-Circuit
Debugger
MCLR(2)
VDD, VSS
ALU<8>
8
Precision
Band Gap
Reference
PORTE
MCLR/VPP/RE3(2)
BOR
HLVD
Data
EEPROM
Timer0
Timer1
Timer2
Timer3
Comparator
CCP1
CCP2
MSSP
EUSART
ADC
10-Bit
Note
8
8
8
Oscillator
Start-up Timer
Power-on
Reset
Watchdog
Timer
8
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1
RC3/SCK/SCL
RC4/SDI/SDA
RC5/SDO
RC6/TX/CK
RC7/RX/DT
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/CLKI and OSC2/CLKO 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 Configurations” for additional information.
DS39631E-page 10
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 1-2:
PIC18F4420/4520 (40/44-PIN) BLOCK DIAGRAM
Data Bus<8>
Table Pointer<21>
Data Memory
( 3.9 Kbytes )
PCLATU PCLATH
21
20
Address Latch
PCU PCH PCL
Program Counter
12
Data Address<12>
31-Level Stack
4
BSR
Address Latch
Program Memory
(16/32 Kbytes)
STKPTR
Data Latch
8
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
OSC2/CLKO(3)/RA6
OSC1/CLKI(3)/RA7
Data Latch
8
8
inc/dec logic
PORTA
12
FSR0
FSR1
FSR2
PORTB
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
RB3/AN9/CCP2(1)
RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
4
Access
Bank
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
State Machine
Control Signals
Instruction
Decode and
Control
PRODH PRODL
3
8 x 8 Multiply
8
W
BITOP
8
Internal
Oscillator
Block
OSC1(3)
OSC2
(3)
T1OSI
INTRC
Oscillator
T1OSO
8 MHz
Oscillator
Single-Supply
Programming
In-Circuit
Debugger
MCLR(2)
VDD, VSS
Power-up
Timer
Brown-out
Reset
Fail-Safe
Clock Monitor
ALU<8>
8
PORTE
Precision
Band Gap
Reference
BOR
HLVD
Data
EEPROM
Timer0
Timer1
Timer2
Timer3
Comparator
ECCP1
CCP2
MSSP
EUSART
ADC
10-Bit
Note
RD0/PSP0 :RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
8
8
8
Oscillator
Start-up Timer
Power-on
Reset
Watchdog
Timer
8
PORTD
RE0/RD/AN5
RE1/WR/AN6
RE2/CS/AN7
MCLR/VPP/RE3(2)
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/CLKI and OSC2/CLKO 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 Configurations” for additional information.
© 2008 Microchip Technology Inc.
DS39631E-page 11
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS
Pin Number
Pin Name
MCLR/VPP/RE3
MCLR
Pin Buffer
SPDIP,
QFN Type Type
SOIC
1
26
VPP
RE3
OSC1/CLKI/RA7
OSC1
9
6
I
ST
P
I
ST
ST
O
—
CLKO
O
—
RA6
I/O
TTL
RA7
OSC2/CLKO/RA6
OSC2
10
Master Clear (input) or programming voltage (input).
Master Clear (Reset) input. This pin is an active-low
Reset to the device.
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/CLKI, OSC2/CLKO
pins.)
I/O
TTL
General purpose I/O pin.
I
CLKI
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 CLKO 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.
DS39631E-page 12
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
Pin Buffer
SPDIP,
QFN Type Type
SOIC
Description
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
AN0
2
RA1/AN1
RA1
AN1
3
RA2/AN2/VREF-/CVREF
RA2
AN2
VREFCVREF
4
RA3/AN3/VREF+
RA3
AN3
VREF+
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
Digital I/O.
Analog input 0.
I/O
TTL
I Analog
Digital I/O.
Analog input 1.
I/O
TTL
I Analog
I Analog
O Analog
Digital I/O.
Analog input 2.
A/D reference voltage (low) input.
Comparator reference voltage output.
I/O
TTL
I Analog
I Analog
Digital I/O.
Analog input 3.
A/D reference voltage (high) input.
I/O
I
O
Digital I/O.
Timer0 external clock input.
Comparator 1 output.
28
1
2
3
ST
ST
—
4
I/O
TTL
I Analog
I
TTL
I Analog
O
—
Digital I/O.
Analog input 4.
SPI slave select input.
High/Low-Voltage Detect input.
Comparator 2 output.
RA6
See the OSC2/CLKO/RA6 pin.
RA7
See the OSC1/CLKI/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.
© 2008 Microchip Technology Inc.
DS39631E-page 13
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
Pin Buffer
SPDIP,
QFN Type Type
SOIC
Description
PORTB is a bidirectional I/O port. PORTB can be software
programmed for internal weak pull-ups on all inputs.
RB0/INT0/FLT0/AN12
RB0
INT0
FLT0
AN12
21
RB1/INT1/AN10
RB1
INT1
AN10
22
RB2/INT2/AN8
RB2
INT2
AN8
23
RB3/AN9/CCP2
RB3
AN9
CCP2(1)
24
RB4/KBI0/AN11
RB4
KBI0
AN11
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.
I/O
TTL
I
ST
I Analog
Digital I/O.
External interrupt 1.
Analog input 10.
I/O
TTL
I
ST
I Analog
Digital I/O.
External interrupt 2.
Analog input 8.
I/O
TTL
I Analog
I/O
ST
Digital I/O.
Analog input 9.
Capture 2 input/Compare 2 output/PWM2 output.
I/O
TTL
I
TTL
I Analog
Digital I/O.
Interrupt-on-change pin.
Analog input 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.
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.
DS39631E-page 14
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Name
Pin Number
Pin Buffer
SPDIP,
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(2)
12
RC2/CCP1
RC2
CCP1
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
8
I/O
O
I
ST
—
ST
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/PWM2 output.
I/O
I/O
ST
ST
Digital I/O.
Capture 1 input/Compare 1 output/PWM1 output.
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).
10
11
12
13
14
15
RE3
—
—
—
—
See MCLR/VPP/RE3 pin.
VSS
8, 19
5, 16
P
—
Ground reference for logic and I/O pins.
VDD
20
17
P
—
Positive supply for logic and I/O pins.
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.
© 2008 Microchip Technology Inc.
DS39631E-page 15
PIC18F2420/2520/4420/4520
TABLE 1-3:
PIC18F4420/4520 PINOUT I/O DESCRIPTIONS
Pin Name
MCLR/VPP/RE3
MCLR
Pin Number
PDIP
1
Pin Buffer
QFN TQFP Type Type
18
18
VPP
RE3
OSC1/CLKI/RA7
OSC1
13
32
ST
P
I
ST
30
I
CLKI
I
RA7
OSC2/CLKO/RA6
OSC2
I
I/O
14
33
Description
Master Clear (input) or programming voltage (input).
Master Clear (Reset) input. This pin is an active-low
Reset to the device.
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/CLKI,
OSC2/CLKO pins.)
TTL
General purpose I/O pin.
ST
31
O
—
CLKO
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 CLKO 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.
DS39631E-page 16
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-3:
PIC18F4420/4520 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
RA0
AN0
2
RA1/AN1
RA1
AN1
3
RA2/AN2/VREF-/CVREF
RA2
AN2
VREFCVREF
4
RA3/AN3/VREF+
RA3
AN3
VREF+
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
TTL
Analog
Digital I/O.
Analog input 0.
I/O
I
TTL
Analog
Digital I/O.
Analog input 1.
I/O
I
I
O
TTL
Analog
Analog
Analog
Digital I/O.
Analog input 2.
A/D reference voltage (low) input.
Comparator reference voltage output.
I/O
I
I
TTL
Analog
Analog
Digital I/O.
Analog input 3.
A/D reference voltage (high) input.
I/O
I
O
ST
ST
—
I/O
I
I
I
O
TTL
Analog
TTL
Analog
—
20
21
22
23
Digital I/O.
Timer0 external clock input.
Comparator 1 output.
24
RA6
RA7
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
O = Output
Digital I/O.
Analog input 4.
SPI slave select input.
High/Low-Voltage Detect input.
Comparator 2 output.
See the OSC2/CLKO/RA6 pin.
See the OSC1/CLKI/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.
© 2008 Microchip Technology Inc.
DS39631E-page 17
PIC18F2420/2520/4420/4520
TABLE 1-3:
PIC18F4420/4520 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-ups on all
inputs.
RB0/INT0/FLT0/AN12
RB0
INT0
FLT0
AN12
33
RB1/INT1/AN10
RB1
INT1
AN10
34
RB2/INT2/AN8
RB2
INT2
AN8
35
RB3/AN9/CCP2
RB3
AN9
CCP2(1)
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.
I/O
I
I
TTL
ST
Analog
Digital I/O.
External interrupt 1.
Analog input 10.
I/O
I
I
TTL
ST
Analog
Digital I/O.
External interrupt 2.
Analog input 8.
I/O
I
I/O
TTL
Analog
ST
Digital I/O.
Analog input 9.
Capture 2 input/Compare 2 output/PWM2 output.
I/O
I
I
TTL
TTL
Analog
Digital I/O.
Interrupt-on-change pin.
Analog input 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.
DS39631E-page 18
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-3:
PIC18F4420/4520 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(2)
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/PWM2 output.
I/O
I/O
O
ST
ST
—
Digital I/O.
Capture 1 input/Compare 1 output/PWM1 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.
© 2008 Microchip Technology Inc.
DS39631E-page 19
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 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.
DS39631E-page 20
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 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 also WR and CS pins).
Analog input 5.
Digital I/O.
Write control for Parallel Slave Port
(see CS and RD pins).
Analog input 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.
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.
© 2008 Microchip Technology Inc.
DS39631E-page 21
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 22
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
2.0
OSCILLATOR
CONFIGURATIONS
2.1
Oscillator Types
PIC18F2420/2520/4420/4520 devices can be operated
in ten different oscillator modes. The user can program
the Configuration bits, FOSC<3:0>, in Configuration
Register 1H to select one of these ten modes:
1.
2.
3.
4.
LP
XT
HS
HSPLL
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. INTIO1 Internal Oscillator with FOSC/4 Output
on RA6 and I/O on RA7
8. INTIO2 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
2.2
Crystal Oscillator/Ceramic
Resonators
In XT, LP, HS or HSPLL Oscillator modes, a crystal or
ceramic resonator is connected to the OSC1 and
OSC2 pins to establish oscillation. Figure 2-1 shows
the pin connections.
The oscillator design requires the use of a parallel cut
crystal.
Note:
Use of a series cut crystal may give a frequency out of the crystal manufacturer’s
specifications.
FIGURE 2-1:
C1(1)
OSC1
XTAL
C2(1)
To
Internal
Logic
RF(3)
Sleep
RS(2)
PIC18FXXXX
OSC2
Note 1:
See Table 2-1 and Table 2-2 for initial values of
C1 and C2.
2:
A series resistor (RS) may be required for AT
strip cut crystals.
3:
RF varies with the oscillator mode chosen.
TABLE 2-1:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
Typical Capacitor Values Used:
Mode
Freq
OSC1
OSC2
XT
3.58 MHz
4.19 MHz
4 MHz
4 MHz
15 pF
15 pF
30 pF
50 pF
15 pF
15 pF
30 pF
50 pF
Capacitor values are for design guidance only.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
VDD and temperature range for the application.
See the notes following Table 2-2 for additional
information.
Note:
© 2008 Microchip Technology Inc.
CRYSTAL/CERAMIC
RESONATOR OPERATION
(XT, LP, HS OR HSPLL
CONFIGURATION)
When using resonators with frequencies
above 3.5 MHz, the use of HS mode,
rather than XT mode, is recommended.
HS mode may be used at any VDD for
which the controller is rated. If HS is
selected, it is possible that the gain of the
oscillator will overdrive the resonator.
Therefore, a series resistor should be
placed between the OSC2 pin and the
resonator. As a good starting point, the
recommended value of RS is 330Ω.
DS39631E-page 23
PIC18F2420/2520/4420/4520
TABLE 2-2:
Osc Type
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Crystal
Freq
Typical Capacitor Values
Tested:
C1
C2
LP
32 kHz
30 pF
30 pF
XT
1 MHz
4 MHz
15 pF
15 pF
15 pF
15 pF
HS
4 MHz
10 MHz
20 MHz
25 MHz
25 MHz
15 pF
15 pF
15 pF
0 pF
15 pF
15 pF
15 pF
15 pF
5 pF
15 pF
Capacitor values are for design guidance only.
These capacitors were tested with the crystals listed
below for basic start-up and operation. These values
are not optimized.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
VDD and temperature range for the application.
See the notes following this table for additional
information.
FIGURE 2-2:
EXTERNAL CLOCK INPUT
OPERATION (HS OSC
CONFIGURATION)
OSC1
Clock from
Ext. System
PIC18FXXXX
Open
2.3
32 kHz
4 MHz
25 MHz
10 MHz
1 MHz
20 MHz
Note 1: Higher capacitance increases the stability
of the oscillator but also increases the
start-up time.
2: When operating below 3V VDD, or when
using certain ceramic resonators at any
voltage, it may be necessary to use the
HS mode or switch to a crystal oscillator.
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate
values
of
external
components.
4: Rs may be required to avoid overdriving
crystals with low drive level specification.
5: Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.
(HS Mode)
OSC2
External Clock Input
The EC and ECIO Oscillator modes require an external
clock source to be connected to the OSC1 pin. There is
no oscillator start-up time required after a Power-on
Reset or after an exit from Sleep mode.
In the EC Oscillator mode, the oscillator frequency
divided by 4 is available on the OSC2 pin. This signal
may be used for test purposes or to synchronize other
logic. Figure 2-3 shows the pin connections for the EC
Oscillator mode.
FIGURE 2-3:
Crystals Used:
DS39631E-page 24
An external clock source may also be connected to the
OSC1 pin in the HS mode, as shown in Figure 2-2.
EXTERNAL CLOCK
INPUT OPERATION
(EC CONFIGURATION)
OSC1/CLKI
Clock from
Ext. System
PIC18FXXXX
FOSC/4
OSC2/CLKO
The ECIO Oscillator mode functions like the EC mode,
except that the OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 6 of
PORTA (RA6). Figure 2-4 shows the pin connections
for the ECIO Oscillator mode.
FIGURE 2-4:
EXTERNAL CLOCK
INPUT OPERATION
(ECIO CONFIGURATION)
OSC1/CLKI
Clock from
Ext. System
PIC18FXXXX
RA6
I/O (OSC2)
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
2.4
RC Oscillator
2.5
For timing insensitive applications, the “RC” and
“RCIO” device options offer additional cost savings.
The actual oscillator frequency is a function of several
factors:
• supply voltage
• values of the external resistor (REXT) and
capacitor (CEXT)
• operating temperature
Given the same device, operating voltage and temperature and component values, there will also be unit-to-unit
frequency variations. These are due to factors such as:
• normal manufacturing variation
• difference in lead frame capacitance between
package types (especially for low CEXT values)
• variations within the tolerance of limits of REXT
and CEXT
In the RC Oscillator mode, the oscillator frequency
divided by 4 is available on the OSC2 pin. This signal
may be used for test purposes or to synchronize other
logic. Figure 2-5 shows how the R/C combination is
connected.
FIGURE 2-5:
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 a 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.
2.5.1
HSPLL OSCILLATOR MODE
The HSPLL mode makes use of the HS Oscillator
mode for frequencies up to 10 MHz. A PLL then multiplies the oscillator output frequency by 4 to produce an
internal clock frequency up to 40 MHz. The PLLEN bit
is not available in this oscillator mode.
The PLL is only available to the crystal oscillator when
the FOSC<3:0> Configuration bits are programmed for
HSPLL mode (= 0110).
FIGURE 2-7:
PLL BLOCK DIAGRAM (HS
MODE)
HS Oscillator Enable
PLL Enable
(from Configuration Register 1H)
RC OSCILLATOR MODE
VDD
OSC2
REXT
OSC1
Internal
Clock
HS Mode
OSC1 Crystal
Osc
FIN
FOUT
Loop
Filter
CEXT
PIC18FXXXX
VSS
FOSC/4
OSC2/CLKO
÷4
The RCIO Oscillator mode (Figure 2-6) functions like
the RC mode, except that the OSC2 pin becomes an
additional general purpose I/O pin. The I/O pin
becomes bit 6 of PORTA (RA6).
RCIO OSCILLATOR MODE
VDD
REXT
OSC1
Internal
Clock
VCO
MUX
Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ
CEXT > 20 pF
FIGURE 2-6:
Phase
Comparator
2.5.2
SYSCLK
PLL AND INTOSC
The PLL is also available to the internal oscillator block
in selected oscillator modes. In this configuration, the
PLL is enabled in software and generates a clock output of up to 32 MHz. The operation of INTOSC with the
PLL is described in Section 2.6.4 “PLL in INTOSC
Modes”.
CEXT
PIC18FXXXX
VSS
RA6
I/O (OSC2)
Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ
CEXT > 20 pF
© 2008 Microchip Technology Inc.
DS39631E-page 25
PIC18F2420/2520/4420/4520
2.6
Internal Oscillator Block
The PIC18F2420/2520/4420/4520 devices include an
internal oscillator block which generates two different
clock signals; either can be used as the microcontroller’s clock source. This may eliminate the need
for external oscillator circuits on the OSC1 and/or
OSC2 pins.
The main output (INTOSC) is an 8 MHz clock source
which can be used to directly drive the device clock. It
also drives a postscaler which can provide a range of
clock frequencies from 31 kHz to 4 MHz. The INTOSC
output is enabled when a clock frequency from 125 kHz
to 8 MHz is selected.
The other clock source is the internal RC oscillator
(INTRC), which provides a nominal 31 kHz output.
INTRC is enabled if it is selected as the device clock
source; it is also enabled automatically when any of the
following are enabled:
•
•
•
•
Power-up Timer
Fail-Safe Clock Monitor
Watchdog Timer
Two-Speed Start-up
These features are discussed in greater detail in
Section 23.0 “Special Features of the CPU”.
The clock source frequency (INTOSC direct, INTRC
direct or INTOSC postscaler) is selected by configuring
the IRCF bits of the OSCCON register (page 30).
2.6.1
INTIO MODES
Using the internal oscillator as the clock source eliminates the need for up to two external oscillator pins,
which can then be used for digital I/O. Two distinct
configurations are available:
• In INTIO1 mode, the OSC2 pin outputs FOSC/4,
while OSC1 functions as RA7 for digital input and
output.
• In INTIO2 mode, OSC1 functions as RA7 and
OSC2 functions as RA6, both for digital input and
output.
2.6.2
INTOSC OUTPUT FREQUENCY
The internal oscillator block is calibrated at the factory
to produce an INTOSC output frequency of 8.0 MHz.
The INTRC oscillator operates independently of the
INTOSC source. Any changes in INTOSC across
voltage and temperature are not necessarily reflected
by changes in INTRC and vice versa.
2.6.3
OSCTUNE REGISTER
The internal oscillator’s output has been calibrated at
the factory but can be adjusted in the user’s application. This is done by writing to the OSCTUNE register
(Register 2-1).
DS39631E-page 26
When the OSCTUNE register is modified, the INTOSC
frequency will begin shifting to the new frequency. The
INTRC clock will reach the new frequency within
8 clock cycles (approximately 8 * 32 μs = 256 μs). The
INTOSC clock will stabilize within 1 ms. Code execution continues during this shift. There is no indication
that the shift has occurred.
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 2.7.1
“Oscillator Control Register”.
The PLLEN bit controls the operation of the frequency
multiplier, PLL, in internal oscillator modes.
2.6.4
PLL IN INTOSC 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 32 MHz.
Unlike HSPLL mode, the PLL is controlled through
software. The control bit, PLLEN (OSCTUNE<6>), is
used to enable or disable its operation.
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 4 MHz or 8 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.
2.6.5
INTOSC FREQUENCY DRIFT
The factory calibrates the internal oscillator block
output (INTOSC) for 8 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 INTOSC frequency by modifying
the value in the OSCTUNE register. This has no effect
on the INTRC clock source frequency.
Tuning the INTOSC 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 compensation techniques are discussed
in Section 2.6.5.1 “Compensating with the
EUSART”, Section 2.6.5.2 “Compensating with the
Timers” and Section 2.6.5.3 “Compensating with the
CCP Module in Capture Mode”, but other techniques
may be used.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 2-1:
OSCTUNE: OSCILLATOR TUNING REGISTER
R/W-0
R/W-0(1)
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
INTSRC
PLLEN(1)
—
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 8 MHz INTOSC source (divide-by-256 enabled)
0 = 31 kHz device clock derived directly from INTRC internal oscillator
bit 6
PLLEN: Frequency Multiplier PLL for INTOSC Enable bit(1)
1 = PLL enabled for INTOSC (4 MHz and 8 MHz only)
0 = PLL disabled
bit 5
Unimplemented: Read as ‘0’
bit 4-0
TUN<4:0>: Frequency Tuning bits
011111 = Maximum frequency
•
•
•
•
000001
000000 = Center frequency. Oscillator module is running at the calibrated frequency.
111111
•
•
•
•
100000 = Minimum frequency
Note 1:
2.6.5.1
Available only in certain oscillator configurations; otherwise, this bit is unavailable and reads as ‘0’. See
Section 2.6.4 “PLL in INTOSC Modes” for details.
Compensating with the EUSART
An adjustment may be required when the EUSART
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.
2.6.5.2
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.
© 2008 Microchip Technology Inc.
2.6.5.3
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.
DS39631E-page 27
PIC18F2420/2520/4420/4520
2.7
Clock Sources and Oscillator
Switching
Like previous PIC18 devices, the PIC18F2420/2520/
4420/4520 family includes a feature that allows the
device clock source to be switched from the main oscillator to an alternate low-frequency clock source.
PIC18F2420/2520/4420/4520 devices offer two alternate
clock sources. When an alternate clock source is enabled,
the various power-managed operating modes are
available.
Essentially, there are three clock sources for these
devices:
• Primary oscillators
• Secondary oscillators
• Internal oscillator block
The primary oscillators include the External Crystal
and Resonator modes, the External RC modes, the
External Clock modes and the internal oscillator block.
The particular mode is defined by the FOSC<3:0> Configuration bits. The details of these modes are covered
earlier in this chapter.
FIGURE 2-8:
The secondary oscillators are those external sources
not connected to the OSC1 or OSC2 pins. These
sources may continue to operate even after the
controller is placed in a power-managed mode.
PIC18F2420/2520/4420/4520 devices offer the Timer1
oscillator as a secondary oscillator. This oscillator, in all
power-managed modes, is often the time base for
functions such as a Real-Time Clock (RTC).
Most often, a 32.768 kHz watch crystal is connected
between the RC0/T1OSO/T13CKI and RC1/T1OSI
pins. Like the LP Oscillator mode circuit, loading
capacitors are also connected from each pin to ground.
The Timer1 oscillator is discussed in greater detail in
Section 12.3 “Timer1 Oscillator”.
In addition to being a primary clock source, the internal
oscillator block is available as a power-managed
mode clock source. The INTRC source is also used as
the clock source for several special features, such as
the WDT and Fail-Safe Clock Monitor.
The clock sources for the PIC18F2420/2520/4420/4520
devices are shown in Figure 2-8. See Section 23.0
“Special Features of the CPU” for Configuration
register details.
PIC18F2420/2520/4420/4520 CLOCK DIAGRAM
PIC18F2420/2520/4420/4520
Primary Oscillator
LP, XT, HS, RC, EC
OSC2
Sleep
4 x PLL
OSC1
OSCTUNE<6>
T1OSC
T1OSO
T1OSCEN
Enable
Oscillator
OSCCON<6:4>
INTRC
Source
4 MHz
2 MHz
8 MHz
(INTOSC)
31 kHz (INTRC)
Postscaler
Internal
Oscillator
Block
8 MHz
Source
1 MHz
500 kHz
250 kHz
125 kHz
Internal Oscillator
CPU
111
110
IDLEN
101
100
011
MUX
8 MHz
OSCCON<6:4>
Peripherals
MUX
Secondary Oscillator
T1OSI
HSPLL, INTOSC/PLL
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
DS39631E-page 28
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
2.7.1
OSCILLATOR CONTROL REGISTER
The OSCCON register (Register 2-2) controls several
aspects of the device clock’s operation, both in full-power
operation and in power-managed modes.
The System Clock Select bits, SCS<1:0>, select the
clock source. The available clock sources are the
primary clock (defined by the FOSC<3:0> Configuration bits), the secondary clock (Timer1 oscillator) and
the internal oscillator block. 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 on all forms of Reset.
The Internal Oscillator Frequency Select bits
(IRCF<2:0>) select the frequency output of the internal
oscillator block to drive the device clock. The choices
are the INTRC source, the INTOSC source (8 MHz) or
one of the frequencies derived from the INTOSC postscaler (31.25 kHz to 4 MHz). If the internal oscillator
block is supplying the device clock, changing the states
of these bits will have an immediate change on the
internal oscillator’s output. On device Resets, the
default output frequency of the internal oscillator block
is set at 1 MHz.
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 in the OSCTUNE register (OSCTUNE<7>).
Setting this bit selects INTOSC as a 31.25 kHz clock
source by enabling the divide-by-256 output of the
INTOSC postscaler. Clearing INTSRC selects INTRC
(nominally 31 kHz) as the clock source.
The IDLEN bit 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 in the Timer1 Control register (T1CON<3>). If the Timer1 oscillator
is not enabled, then any attempt to select
a secondary clock source will be ignored.
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.
2.7.2
OSCILLATOR TRANSITIONS
PIC18F2420/2520/4420/4520 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”.
This option allows users to select the tunable and more
precise INTOSC as a clock source, while maintaining
power savings with a very low clock speed. Regardless
of the setting of INTSRC, INTRC always remains the
clock source for features such as the Watchdog Timer
and the Fail-Safe Clock Monitor.
The OSTS, IOFS and T1RUN bits indicate which clock
source is currently providing the device clock. The
OSTS bit indicates that the Oscillator Start-up Timer
(OST) has timed out and the primary clock is providing
the device clock in primary clock modes. The IOFS bit
indicates when the internal oscillator block has stabilized and is providing the device clock in RC Clock
modes. The T1RUN bit (T1CON<6>) indicates when
the Timer1 oscillator is providing the device clock in
secondary clock modes. In power-managed modes,
only one of these three bits will be set at any time. If
none of these bits are set, the INTRC is providing the
clock or the internal oscillator block has just started and
is not yet stable.
© 2008 Microchip Technology Inc.
DS39631E-page 29
PIC18F2420/2520/4420/4520
REGISTER 2-2:
OSCCON: OSCILLATOR CONTROL REGISTER
R/W-0
R/W-1
R/W-0
R/W-0
R(1)
R-0
R/W-0
R/W-0
IDLEN
IRCF2
IRCF1
IRCF0
OSTS
IOFS
SCS1
SCS0
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
IDLEN: Idle Enable bit
1 = Device enters an 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 = 8 MHz (INTOSC drives clock directly)
110 = 4 MHz
101 = 2 MHz
100 = 1 MHz(3)
011 = 500 kHz
010 = 250 kHz
001 = 125 kHz
000 = 31 kHz (from either INTOSC/256 or INTRC directly)(2)
bit 3
OSTS: Oscillator Start-up Timer Time-out Status bit(1)
1 = Oscillator Start-up Timer (OST) time-out has expired; primary oscillator is running
0 = Oscillator Start-up Timer (OST) time-out is running; primary oscillator is not ready
bit 2
IOFS: INTOSC Frequency Stable bit
1 = INTOSC frequency is stable
0 = INTOSC frequency is not stable
bit 1-0
SCS<1:0>: System Clock Select bits
1x = Internal oscillator block
01 = Secondary (Timer1) oscillator
00 = Primary oscillator
Note 1:
2:
3:
Reset state depends on state of the IESO Configuration bit.
Source selected by the INTSRC bit (OSCTUNE<7>), see text.
Default output frequency of INTOSC on Reset.
DS39631E-page 30
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
2.8
Effects of Power-Managed Modes
on the Various Clock Sources
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 (RC_RUN and RC_IDLE),
the internal oscillator block provides the device clock
source. The 31 kHz INTRC output can be used directly
to provide the clock and may be enabled to support
various special features, regardless of the powermanaged mode (see Section 23.2 “Watchdog Timer
(WDT)”, Section 23.3 “Two-Speed Start-up” and
Section 23.4 “Fail-Safe Clock Monitor” for more
information on WDT, Fail-Safe Clock Monitor and TwoSpeed Start-up). The INTOSC output at 8 MHz may be
used directly to clock the device or may be divided
down by the postscaler. The INTOSC output is disabled
if the clock is provided directly from the INTRC output.
If 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 INTRC is required to support WDT operation. The
Timer1 oscillator may be operating to support a RealTime Clock. Other features may be operating that do
TABLE 2-3:
not require a device clock source (i.e., MSSP slave,
PSP, INTx pins and others). Peripherals that may add
significant current consumption are listed in
Section 26.2 “DC Characteristics”.
2.9
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.
OSC1 AND OSC2 PIN STATES IN SLEEP MODE
OSC Mode
OSC1 Pin
OSC2 Pin
RC, INTIO1
Floating, external resistor should pull high
At logic low (clock/4 output)
RCIO
Floating, external resistor should pull high
Configured as PORTA, bit 6
INTIO2
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 and HS
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.
© 2008 Microchip Technology Inc.
DS39631E-page 31
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 32
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
3.0
3.1.1
POWER-MANAGED MODES
The SCS<1:0> bits allow the selection of one of three
clock sources for power-managed modes. They are:
PIC18F2420/2520/4420/4520 devices offer a total of
seven operating modes for more efficient powermanagement. 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 (for RC modes)
There are three categories of power-managed modes:
3.1.2
• Run modes
• Idle modes
• Sleep mode
The power-managed modes include several powersaving features offered on previous PIC® devices. One
is the clock switching feature, offered in other PIC18
devices, allowing the controller to use the Timer1
oscillator in place of the primary oscillator. Also
included is the Sleep mode, offered by all PIC devices,
where all device clocks are stopped.
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.
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: if the CPU is to be clocked or not and the
selection of a clock source. The IDLEN bit
(OSCCON<7>) controls CPU clocking, while the
SCS<1:0> bits (OSCCON<1:0>) select the clock
source. The individual modes, bit settings, clock sources
and affected modules are summarized in Table 3-1.
TABLE 3-1:
Mode
Sleep
ENTERING POWER-MANAGED
MODES
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.
3.1
CLOCK SOURCES
POWER-MANAGED MODES
OSCCON<7,1:0> Bits
Module Clocking
IDLEN(1)
SCS<1:0>
CPU
Available Clock and Oscillator Source
Peripherals
0
N/A
Off
Off
PRI_RUN
N/A
00
Clocked
Clocked
Primary – LP, XT, HS, HSPLL, RC, EC and
Internal Oscillator Block(2).
This is the normal full-power execution mode.
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)
Note 1:
2:
None – All clocks are disabled
IDLEN reflects its value when the SLEEP instruction is executed.
Includes INTOSC and INTOSC postscaler, as well as the INTRC source.
© 2008 Microchip Technology Inc.
Advance Information
DS39631E-page 33
PIC18F2420/2520/4420/4520
3.1.3
CLOCK TRANSITIONS AND STATUS
INDICATORS
The length of the transition between clock sources 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.
Three bits indicate the current clock source and its
status. They are:
• OSTS (OSCCON<3>)
• IOFS (OSCCON<2>)
• T1RUN (T1CON<6>)
In general, only one of these bits will be set while in a
given power-managed mode. When the OSTS bit is
set, the primary clock is providing the device clock.
When the IOFS bit is set, the INTOSC output is
providing a stable 8 MHz clock source to a divider that
actually drives the device clock. When the T1RUN bit is
set, the Timer1 oscillator is providing the clock. If none
of these bits are set, then either the INTRC clock
source is clocking the device or the INTOSC source is
not yet stable.
If the internal oscillator block is configured as the
primary clock source by the FOSC<3:0> Configuration
bits, then both the OSTS and IOFS bits may be set
when in PRI_RUN or PRI_IDLE modes. This indicates
that the primary clock (INTOSC output) is generating a
stable 8 MHz output. Entering another power-managed
RC mode at the same frequency would clear the OSTS
bit.
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
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 Start-up
is enabled (see Section 23.3 “Two-Speed Start-up”
for details). In this mode, the OSTS bit is set. The IOFS
bit may be set if the internal oscillator block is the
primary clock source (see Section 2.7.1 “Oscillator
Control Register”).
3.2.2
3.1.4
MULTIPLE SLEEP COMMANDS
The power-managed mode that is invoked with the
SLEEP instruction is determined by the setting of the
IDLEN bit at the time the instruction is executed. If
another SLEEP instruction is executed, the device will
enter the power-managed mode specified by IDLEN at
that time. If IDLEN has changed, the device will enter
the new power-managed mode specified by the new
setting.
DS39631E-page 34
SEC_RUN MODE
The SEC_RUN mode is the compatible mode 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’. The device clock source is switched to the
Timer1 oscillator (see Figure 3-1), the primary oscillator is shut down, the T1RUN bit (T1CON<6>) is set and
the OSTS bit is cleared.
Note:
Note 1: Caution should be used when modifying a
single IRCF bit. If VDD is less than 3V, it is
possible to select a higher clock speed
than is supported by the low VDD.
Improper device operation may result if
the VDD/FOSC specifications are violated.
2: 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.
PRI_RUN MODE
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. If the
Timer1 oscillator is enabled, but not yet
running, device clocks will be delayed until
the oscillator has started. In such situations, initial oscillator operation is far from
stable and unpredictable operation may
result.
On transitions from SEC_RUN mode to PRI_RUN
mode, 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 3-2). When the clock switch is complete, the
T1RUN bit is cleared, the OSTS bit is set and the
primary clock is providing the clock. The IDLEN and
SCS bits are not affected by the wake-up; the Timer1
oscillator continues to run.
Advance Information
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 3-1:
TRANSITION TIMING FOR ENTRY TO SEC_RUN MODE
Q1 Q2 Q3 Q4 Q1
Q2
1
T1OSI
2
3
n-1
Q3
Q4
Q1
Q2
Q3
n
Clock Transition(1)
OSC1
CPU
Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 4
Note 1: Clock transition typically occurs within 2-4 TOSC.
FIGURE 3-2:
TRANSITION TIMING FROM SEC_RUN MODE TO PRI_RUN MODE (HSPLL)
Q1
Q2
Q3
Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3
T1OSI
OSC1
TOST(1)
TPLL(1)
1
PLL Clock
Output
2
n-1 n
Clock
Transition(2)
CPU Clock
Peripheral
Clock
Program
Counter
PC + 2
PC
SCS<1:0> bits Changed
PC + 4
OSTS bit Set
Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
2: Clock transition typically occurs within 2-4 TOSC.
3.2.3
RC_RUN MODE
In RC_RUN mode, the CPU and peripherals are
clocked from the internal oscillator block using the
INTOSC multiplexer. In this mode, the primary clock is
shut down. When using the INTRC source, this mode
provides the best power conservation of all the Run
modes while still executing code. It works well for user
applications which are not highly timing sensitive or do
not require high-speed clocks at all times.
This mode is entered by setting the SCS1 bit to ‘1’.
Although it is ignored, it is recommended that the SCS0
bit also be cleared; this is to maintain software compatibility with future devices. When the clock source is
switched to the INTOSC multiplexer (see Figure 3-3),
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.
Note:
If the primary clock source is the internal oscillator
block (either INTRC or INTOSC), 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.
© 2008 Microchip Technology Inc.
Advance Information
Caution should be used when modifying a
single IRCF bit. If VDD is less than 3V, it is
possible to select a higher clock speed
than is supported by the low VDD.
Improper device operation may result if
the VDD/FOSC specifications are violated.
DS39631E-page 35
PIC18F2420/2520/4420/4520
If the IRCF bits and the INTSRC bit are all clear, the
INTOSC output is not enabled and the IOFS bit will
remain clear; there will be no indication of the current
clock source. The INTRC source is providing the
device clocks.
On transitions from RC_RUN mode to PRI_RUN mode,
the device continues to be clocked from the INTOSC
multiplexer while the primary clock is started. When the
primary clock becomes ready, a clock switch to the primary clock occurs (see Figure 3-4). When the clock
switch is complete, the IOFS bit is cleared, the OSTS
bit is set and the primary clock is providing the device
clock. The IDLEN and SCS bits are not affected by the
switch. The INTRC source will continue to run if either
the WDT or the Fail-Safe Clock Monitor is enabled.
If the IRCF bits are changed from all clear (thus,
enabling the INTOSC output), or if INTSRC is set, the
IOFS bit becomes set after the INTOSC output
becomes stable. Clocks to the device continue while
the INTOSC source stabilizes after an interval of
TIOBST.
If the IRCF bits were previously at a non-zero value, or
if INTSRC was set before setting SCS1 and the
INTOSC source was already stable, the IOFS bit will
remain set.
FIGURE 3-3:
TRANSITION TIMING TO RC_RUN MODE
Q1 Q2 Q3 Q4 Q1
Q2
1
INTRC
2
3
n-1
Q3
Q4
Q1
Q2
Q3
n
(1)
Clock Transition
OSC1
CPU
Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 4
Note 1: Clock transition typically occurs within 2-4 TOSC.
FIGURE 3-4:
TRANSITION TIMING FROM RC_RUN MODE TO PRI_RUN MODE
Q1
Q2
Q3
Q4
Q2 Q3 Q4 Q1 Q2 Q3
Q1
INTOSC
Multiplexer
OSC1
TOST(1)
TPLL(1)
1
PLL Clock
Output
2
n-1 n
Clock
Transition(2)
CPU Clock
Peripheral
Clock
Program
Counter
PC + 2
PC
SCS<1:0> bits Changed
PC + 4
OSTS bit Set
Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
2: Clock transition typically occurs within 2-4 TOSC.
DS39631E-page 36
Advance Information
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
3.3
Sleep Mode
3.4
The power-managed Sleep mode in the PIC18F2420/
2520/4420/4520 devices is identical to the legacy
Sleep mode offered in all other PIC 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 3-5). All
clock source status bits are cleared.
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 ‘1’ when a SLEEP instruction is
executed, the peripherals will be clocked from the clock
source selected using 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.
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 INTRC source will continue to
operate. If the Timer1 oscillator is enabled, it will also
continue to run.
If the WDT is selected, the INTRC 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 3-6), 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.
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 SCS1:SCS0 bits.
FIGURE 3-5:
TRANSITION TIMING FOR ENTRY TO SLEEP MODE
Q1 Q2 Q3 Q4 Q1
OSC1
CPU
Clock
Peripheral
Clock
Sleep
Program
Counter
PC
FIGURE 3-6:
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
TOST(1)
PLL Clock
Output
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.
© 2008 Microchip Technology Inc.
Advance Information
DS39631E-page 37
PIC18F2420/2520/4420/4520
3.4.1
PRI_IDLE MODE
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 3-7).
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 3-8).
Note:
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 3-8).
3.4.2
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 SLEEP
instruction will be ignored and entry to
SEC_IDLE mode will not occur. If the
Timer1 oscillator is enabled but not yet
running, peripheral clocks will be delayed
until the oscillator has started. In such
situations, initial oscillator operation is far
from stable and unpredictable operation
may result.
SEC_IDLE MODE
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
FIGURE 3-7:
TRANSITION TIMING FOR ENTRY TO IDLE MODE
Q1
Q3
Q2
Q4
Q1
OSC1
CPU Clock
Peripheral
Clock
Program
Counter
PC
FIGURE 3-8:
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
DS39631E-page 38
Advance Information
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 using the INTOSC multiplexer. 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. Although its value is
ignored, it is recommended that SCS0 also be cleared;
this is to maintain software compatibility with future
devices. The INTOSC 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 INTOSC 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 INTOSC output is enabled. The
IOFS bit becomes set, after the INTOSC output
becomes stable, after an interval of TIOBST
(parameter 39, Table 26-10). Clocks to the peripherals
continue while the INTOSC 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 INTOSC source was already stable, the
IOFS bit will remain set. If the IRCF bits and INTSRC
are all clear, the INTOSC 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 INTOSC multiplexer. After a delay of
TCSD following the wake event, the CPU begins
executing code being clocked by the INTOSC multiplexer. The IDLEN and SCS bits are not affected by the
wake-up. The INTRC 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 an interrupt, a Reset or a WDT 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”).
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 exit sequence is
initiated when the corresponding interrupt flag bit is set.
© 2008 Microchip Technology Inc.
On all exits from Idle or Sleep modes by interrupt, code
execution branches to the interrupt vector if the GIE/
GIEH bit (INTCON<7>) is set. Otherwise, code execution continues or resumes 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
executing a SLEEP or CLRWDT instruction, the loss of a
currently selected clock source (if the Fail-Safe Clock
Monitor is enabled) and modifying the IRCF bits in the
OSCCON register if the internal oscillator block is the
device clock source.
3.5.3
EXIT BY RESET
Normally, the device is held in Reset by the Oscillator
Start-up Timer (OST) until the primary clock becomes
ready. At that time, the OSTS bit is set and the device
begins executing code. If the internal oscillator block is
the new clock source, the IOFS bit is set instead.
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 if the
new clock source is the primary clock. Exit delays are
summarized in Table 3-2.
Code execution can begin before the primary clock
becomes ready. If either the Two-Speed Start-up (see
Section 23.3 “Two-Speed Start-up”) or Fail-Safe
Clock Monitor (see Section 23.4 “Fail-Safe Clock
Monitor”) is enabled, the device may begin execution
as soon as the Reset source has cleared. Execution is
clocked by the INTOSC multiplexer driven by the internal oscillator block. Execution is clocked by the internal
oscillator block until either the primary clock becomes
ready or a power-managed mode is entered before the
primary clock becomes ready; the primary clock is then
shut down.
Advance Information
DS39631E-page 39
PIC18F2420/2520/4420/4520
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 3-2:
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 and INTIO
Oscillator 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)
INTOSC(2)
T1OSC or INTRC(1)
INTOSC(2)
None
(Sleep mode)
Note 1:
2:
3:
OSTS
IOFS
LP, XT, HS
TOST(3)
HSPLL
TOST + trc(3)
OSTS
EC, RC
INTOSC(2)
TCSD(1)
TCSD(1)
IOFS
LP, XT, HS
TOST(3)
HSPLL
TOST + trc(3)
EC, RC
TCSD(1)
INTOSC(2)
TCSD(1)
LP, XT, HS
TOST(3)
HSPLL
TOST + trc(3)
EC, RC
TCSD(1)
INTOSC(2)
TCSD(1)
OSTS
IOFS
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, INTOSC defaults to 1 MHz.
Includes both the INTOSC 8 MHz source and postscaler derived frequencies.
TOST is the Oscillator Start-up Timer (parameter 32). trc is the PLL lock-out timer (parameter F12); it is also
designated as TPLL.
DS39631E-page 40
Advance Information
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
4.0
RESET
The PIC18F2420/2520/4420/4520 devices differentiate
between various kinds of Reset:
a)
b)
c)
d)
e)
f)
g)
h)
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:
A simplified block diagram of the On-Chip Reset Circuit
is shown in 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 Rise
Detect
POR Pulse
VDD
Brown-out
Reset
BOREN
S
OST/PWRT
OST
1024 Cycles
10-Bit Ripple Counter
OSC1
32 μs
INTRC(1)
PWRT
Chip_Reset
R
Q
65.5 ms
11-Bit Ripple Counter
Enable PWRT
Enable OST(2)
Note 1:
2:
This is the INTRC source from the internal oscillator block and is separate from the RC oscillator of the CLKI pin.
See Table 4-2 for time-out situations.
© 2008 Microchip Technology Inc.
DS39631E-page 41
PIC18F2420/2520/4420/4520
REGISTER 4-1:
RCON: RESET CONTROL REGISTER
R/W-0
R/W-1(1)
U-0
R/W-1
R-1
R-1
R/W-0(2)
R/W-0
IPEN
SBOREN
—
RI
TO
PD
POR
BOR
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
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 BOREN1:BOREN0 = 01:
1 = BOR is enabled
0 = BOR is disabled
If BOREN1:BOREN0 = 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 only)
0 = The RESET instruction was executed causing a device Reset (must be set in software after a
Brown-out 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
1 = A Power-on Reset has not occurred (set by firmware only)
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
1 = A Brown-out Reset has not occurred (set by firmware only)
0 = A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs)
Note 1:
2:
If SBOREN is enabled, its 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.
Note 1: 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.
2: Brown-out Reset is said to have occurred when BOR is ‘0’ and POR is ‘1’ (assuming that POR was set to
‘1’ by software immediately after a Power-on Reset).
DS39631E-page 42
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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:
In PIC18F2420/2520/4420/4520 devices, the MCLR
input can be disabled with the MCLRE Configuration
bit. When MCLR is disabled, the pin becomes a digital
input. See Section 10.5 “PORTE, TRISE and LATE
Registers” for more information.
4.3
D
To take advantage of the POR circuitry, tie the MCLR
pin through a resistor (1 kΩ to 10 kΩ) 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
C
MCLR
PIC18FXXXX
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:
R < 40 kΩ is recommended to make sure that
the voltage drop across R does not violate
the device’s electrical specification.
3:
R1 ≥ 1 kΩ 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.
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 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 (RCON<1>).
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 manually resets the bit to ‘1’
in software following any POR.
© 2008 Microchip Technology Inc.
DS39631E-page 43
PIC18F2420/2520/4420/4520
4.4
Brown-out Reset (BOR)
PIC18F2420/2520/4420/4520 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>
Configuration bits. 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-up Timer (PWRT) are
independently configured. Enabling the Brown-out
Reset does not automatically enable the PWRT.
4.4.1
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
control bit, SBOREN (RCON<6>). 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’.
TABLE 4-1:
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:
4.4.2
Even when BOR is under software control,
the Brown-out Reset voltage level is still
set by the BORV<1:0> Configuration bits;
it cannot be changed in software.
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 bit is reset to ‘1’ in 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.
4.4.3
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.
BOR CONFIGURATIONS
BOR Configuration
BOREN1
BOREN0
Status of
SBOREN
(RCON<6>)
0
0
Unavailable
0
1
Available
1
0
Unavailable
BOR enabled in hardware in Run and Idle modes, disabled during
Sleep mode.
1
1
Unavailable
BOR enabled in hardware; must be disabled by reprogramming the
Configuration bits.
DS39631E-page 44
BOR Operation
BOR disabled; must be enabled by reprogramming the Configuration bits.
BOR enabled in software; operation controlled by SBOREN.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
4.5
4.5.3
Device Reset Timers
PIC18F2420/2520/4420/4520 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
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:
POWER-UP TIMER (PWRT)
The Power-up Timer (PWRT) of PIC18F2420/2520/
4420/4520 devices is an 11-bit counter which uses
the INTRC source as the clock input. This yields an
approximate time interval of 2048 x 32 μs = 65.6 ms.
While the PWRT is counting, the device is held in
Reset.
The power-up time delay depends on the INTRC 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
PLL LOCK TIME-OUT
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.
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. Figure 4-3 through Figure 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. Bringing MCLR high will begin execution immediately
(Figure 4-5). This is useful for testing purposes or to
synchronize more than one PIC18FXXXX device
operating in parallel.
The OST time-out is invoked only for XT, LP, HS and
HSPLL modes and only on Power-on Reset, or on exit
from most power-managed modes.
TABLE 4-2:
TIME-OUT IN VARIOUS SITUATIONS
Power-up(2) and Brown-out
Oscillator
Configuration
HSPLL
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.
© 2008 Microchip Technology Inc.
DS39631E-page 45
PIC18F2420/2520/4420/4520
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
FIGURE 4-4:
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
TOST
OST TIME-OUT
INTERNAL RESET
FIGURE 4-5:
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
TOST
OST TIME-OUT
INTERNAL RESET
DS39631E-page 46
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
TIME-OUT SEQUENCE ON POR W/PLL ENABLED (MCLR TIED TO VDD)
FIGURE 4-7:
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.
© 2008 Microchip Technology Inc.
DS39631E-page 47
PIC18F2420/2520/4420/4520
4.6
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.
Reset State of Registers
Most registers are unaffected by a Reset. Their status
is unknown on POR and unchanged by all other
Resets. The other registers are forced to a “Reset
state” depending on the type of Reset that occurred.
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 in software to determine the nature of the
Reset.
TABLE 4-3:
STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION
FOR RCON REGISTER
RCON Register
STKPTR Register
Program
Counter
RI
TO
PD
POR
BOR
STKFUL
STKUNF
Power-on Reset
0000h
1
1
1
0
0
0
0
RESET Instruction
0000h
0
u
u
u
u
u
u
Brown-out Reset
0000h
1
1
1
u
0
u
u
MCLR Reset during Power-Managed
Run Modes
0000h
u
1
u
u
u
u
u
MCLR Reset during Power-Managed
Idle Modes and Sleep Mode
0000h
u
1
0
u
u
u
u
WDT Time-out during Full Power or
Power-Managed Run Mode
0000h
u
0
u
u
u
u
u
MCLR Reset during Full-Power
Execution
0000h
u
u
u
u
u
u
u
Condition
Stack Full Reset (STVREN = 1)
0000h
u
u
u
u
u
1
u
Stack Underflow Reset (STVREN = 1)
0000h
u
u
u
u
u
u
1
Stack Underflow Error (not an actual
Reset, STVREN = 0)
0000h
u
u
u
u
u
u
1
WDT Time-out during
Power-Managed Idle or Sleep Modes
PC + 2
u
0
0
u
u
u
u
PC + 2(1)
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).
DS39631E-page 48
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS
Register
Applicable Devices
Power-on Reset,
Brown-out Reset
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
TOSU
2420
2520
4420
4520
---0 0000
---0 0000
---0 uuuu(3)
TOSH
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu(3)
TOSL
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu(3)
STKPTR
2420
2520
4420
4520
00-0 0000
uu-0 0000
uu-u uuuu(3)
PCLATU
2420
2520
4420
4520
---0 0000
---0 0000
---u uuuu
PCLATH
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
PCL
2420
2520
4420
4520
0000 0000
0000 0000
PC + 2(2)
TBLPTRU
2420
2520
4420
4520
--00 0000
--00 0000
--uu uuuu
TBLPTRH
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
TBLPTRL
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
TABLAT
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
PRODH
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
PRODL
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
INTCON
2420
2520
4420
4520
0000 000x
0000 000u
uuuu uuuu(1)
INTCON2
2420
2520
4420
4520
1111 -1-1
1111 -1-1
uuuu -u-u(1)
INTCON3
2420
2520
4420
4520
11-0 0-00
11-0 0-00
uu-u u-uu(1)
INDF0
2420
2520
4420
4520
N/A
N/A
N/A
POSTINC0
2420
2520
4420
4520
N/A
N/A
N/A
POSTDEC0
2420
2520
4420
4520
N/A
N/A
N/A
PREINC0
2420
2520
4420
4520
N/A
N/A
N/A
PLUSW0
2420
2520
4420
4520
N/A
N/A
N/A
FSR0H
2420
2520
4420
4520
---- 0000
---- 0000
---- uuuu
FSR0L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
WREG
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
INDF1
2420
2520
4420
4520
N/A
N/A
N/A
POSTINC1
2420
2520
4420
4520
N/A
N/A
N/A
POSTDEC1
2420
2520
4420
4520
N/A
N/A
N/A
PREINC1
2420
2520
4420
4520
N/A
N/A
N/A
PLUSW1
2420
2520
4420
4520
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’.
The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When
PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111.
© 2008 Microchip Technology Inc.
DS39631E-page 49
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Register
Power-on Reset,
Brown-out Reset
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
4520
---- 0000
---- 0000
---- uuuu
Applicable Devices
FSR1H
2420
2520
4420
FSR1L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
BSR
2420
2520
4420
4520
---- 0000
---- 0000
---- uuuu
INDF2
2420
2520
4420
4520
N/A
N/A
N/A
POSTINC2
2420
2520
4420
4520
N/A
N/A
N/A
POSTDEC2
2420
2520
4420
4520
N/A
N/A
N/A
PREINC2
2420
2520
4420
4520
N/A
N/A
N/A
PLUSW2
2420
2520
4420
4520
N/A
N/A
N/A
FSR2H
2420
2520
4420
4520
---- 0000
---- 0000
---- uuuu
FSR2L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
STATUS
2420
2520
4420
4520
---x xxxx
---u uuuu
---u uuuu
TMR0H
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
TMR0L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
T0CON
2420
2520
4420
4520
1111 1111
1111 1111
uuuu uuuu
OSCCON
2420
2520
4420
4520
0100 q000
0100 q000
uuuu quuu
HLVDCON
2420
2520
4420
4520
0-00 0101
0-00 0101
u-uu uuuu
WDTCON
2420
2520
4420
4520
---- ---0
---- ---0
---- ---u
(4)
2420
2520
4420
4520
0q-1 11q0
0q-q qquu
uq-u qquu
TMR1H
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
TMR1L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
T1CON
2420
2520
4420
4520
0000 0000
u0uu uuuu
uuuu uuuu
TMR2
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
PR2
2420
2520
4420
4520
1111 1111
1111 1111
1111 1111
T2CON
2420
2520
4420
4520
-000 0000
-000 0000
-uuu uuuu
SSPBUF
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
SSPADD
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
SSPSTAT
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
SSPCON1
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
SSPCON2
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
RCON
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’.
The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When
PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111.
DS39631E-page 50
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Register
ADRESH
Power-on Reset,
Brown-out Reset
Applicable Devices
2420
2520
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
uuuu uuuu
ADRESL
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
ADCON0
2420
2520
4420
4520
--00 0000
--00 0000
--uu uuuu
ADCON1
2420
2520
4420
4520
--00 0qqq(6)
--00 0qqq(6)
--uu uuuu
ADCON2
2420
2520
4420
4520
0-00 0000
0-00 0000
u-uu uuuu
CCPR1H
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
CCPR1L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
2420
2520
4420
4520
--00 0000
--00 0000
--uu uuuu
CCPR2H
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
CCPR2L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
CCP2CON
2420
2520
4420
4520
--00 0000
--00 0000
--uu uuuu
BAUDCON
2420
2520
4420
4520
0100 0-00
0100 0-00
uuuu u-uu
CCP1CON
PWM1CON
ECCP1AS
CVRCON
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
2420
2520
4420
4520
0000 00--
0000 00--
uuuu uu--
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
CMCON
2420
2520
4420
4520
0000 0111
0000 0111
uuuu uuuu
TMR3H
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
TMR3L
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
T3CON
2420
2520
4420
4520
0000 0000
uuuu uuuu
uuuu uuuu
SPBRGH
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
SPBRG
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
RCREG
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
TXREG
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
TXSTA
2420
2520
4420
4520
0000 0010
0000 0010
uuuu uuuu
RCSTA
2420
2520
4420
4520
0000 000x
0000 000x
uuuu uuuu
EEADR
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
EEDATA
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
EECON2
2420
2520
4420
4520
0000 0000
0000 0000
0000 0000
EECON1
2420
2520
4420
4520
xx-0 x000
uu-0 u000
uu-0 u000
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’.
The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When
PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111.
© 2008 Microchip Technology Inc.
DS39631E-page 51
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Register
Power-on Reset,
Brown-out Reset
Applicable Devices
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
IPR2
2420
2520
4420
4520
11-1 1111
11-1 1111
uu-u uuuu
PIR2
2420
2520
4420
4520
00-0 0000
00-0 0000
uu-u uuuu(1)
PIE2
IPR1
PIR1
2420
2520
4420
4520
00-0 0000
00-0 0000
uu-u uuuu
2420
2520
4420
4520
1111 1111
1111 1111
uuuu uuuu
2420
2520
4420
4520
-111 1111
-111 1111
-uuu uuuu
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu(1)
2420
2520
4420
4520
-000 0000
-000 0000
-uuu uuuu(1)
2420
2520
4420
4520
0000 0000
0000 0000
uuuu uuuu
2420
2520
4420
4520
-000 0000
-000 0000
-uuu uuuu
OSCTUNE
2420
2520
4420
4520
00-0 0000
00-0 0000
uu-u uuuu
TRISE
2420
2520
4420
4520
0000 -111
0000 -111
uuuu -uuu
PIE1
TRISD
2420
2520
4420
4520
1111 1111
1111 1111
uuuu uuuu
TRISC
2420
2520
4420
4520
1111 1111
1111 1111
uuuu uuuu
TRISB
2420
2520
4420
4520
1111 1111
1111 1111
uuuu uuuu
TRISA(5)
2420
2520
4420
4520
1111 1111(5)
1111 1111(5)
uuuu uuuu(5)
LATE
2420
2520
4420
4520
---- -xxx
---- -uuu
---- -uuu
LATD
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
LATC
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
LATB
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
LATA(5)
2420
2520
4420
4520
xxxx xxxx(5)
uuuu uuuu(5)
uuuu uuuu(5)
PORTE
2420
2520
4420
4520
---- xxxx
---- uuuu
---- uuuu
PORTD
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
PORTC
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
PORTB
2420
2520
4420
4520
xxxx xxxx
uuuu uuuu
uuuu uuuu
PORTA(5)
2420
2520
4420
4520
xx0x 0000(5)
uu0u 0000(5)
uuuu uuuu(5)
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’.
The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When
PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111.
DS39631E-page 52
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
5.0
MEMORY ORGANIZATION
5.1
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.
The PIC18F2420 and PIC18F4420 each have 16 Kbytes
of Flash memory and can store up to 8,192 single-word
instructions. The PIC18F2520 and PIC18F4520 each
have 32 Kbytes of Flash memory and can store up to
16,384 single-word instructions.
PIC18 devices have two interrupt vectors. The Reset
vector address is at 0000h and the interrupt vector
addresses are at 0008h and 0018h.
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”.
FIGURE 5-1:
Program Memory Organization
The program memory map for PIC18F2420/2520/
4420/4520 devices is shown in Figure 5-1.
PROGRAM MEMORY MAP AND STACK FOR
PIC18F2420/2520/4420/4520 DEVICES
PC<20:0>
CALL,RCALL,RETURN
RETFIE,RETLW
Stack Level 1
21
•
•
•
Stack Level 31
Reset Vector
0000h
High-Priority Interrupt Vector
0008h
Low-Priority Interrupt Vector
0018h
On-Chip
Program Memory
On-Chip
Program Memory
User Memory Space
3FFFh
4000h
PIC18F2420/4420
7FFFh
8000h
PIC18F2520/4520
Read ‘0’
Read ‘0’
1FFFFFh
200000h
© 2008 Microchip Technology Inc.
DS39631E-page 53
PIC18F2420/2520/4420/4520
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 Function 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 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
DS39631E-page 54
STKPTR<4:0>
00010
TOSL
34h
Top-of-Stack
Stack Pointer
001A34h
000D58h
00011
00010
00001
00000
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
5.1.2.2
Return Stack Pointer (STKPTR)
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.
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.
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.
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:
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.
Note:
5.1.2.3
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.
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 PUSH instruction places the current PC value onto
the stack. This increments the Stack Pointer and loads
the current PC value onto the stack.
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:
C = Clearable bit
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
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:
x = Bit is unknown
Bit 7 and bit 6 are cleared by user software or by a POR.
© 2008 Microchip Technology Inc.
DS39631E-page 55
PIC18F2420/2520/4420/4520
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 in 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
DS39631E-page 56
;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”.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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/CLKO
(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.
© 2008 Microchip Technology Inc.
DS39631E-page 57
PIC18F2420/2520/4420/4520
5.2.3
INSTRUCTIONS IN PROGRAM
MEMORY
The program memory is addressed in bytes. Instructions are stored as 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 instructions 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 and used by
EXAMPLE 5-4:
Word Address
↓
000000h
000002h
000004h
000006h
000008h
00000Ah
00000Ch
00000Eh
000010h
000012h
000014h
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
DS39631E-page 58
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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; PIC18F2420/
2520/4420/4520 devices implement all 16 banks.
Figure 5-5 shows the data memory organization for the
PIC18F2420/2520/4420/4520 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
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 Figure 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 map in
Figure 5-5 indicates 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.
© 2008 Microchip Technology Inc.
DS39631E-page 59
PIC18F2420/2520/4420/4520
FIGURE 5-5:
DATA MEMORY MAP FOR PIC18F2420/4420 DEVICES
BSR<3:0>
= 0000
= 0001
= 0010
= 0011
= 0100
= 0101
= 0110
= 0111
= 1000
= 1001
= 1010
= 1011
= 1100
= 1101
= 1110
= 1111
DS39631E-page 60
When ‘a’ = 0:
Data Memory Map
00h
Access RAM
FFh
00h
GPR
Bank 0
GPR
Bank 1
Bank 2
Bank 3
Bank 4
Bank 5
Bank 6
Bank 7
Bank 8
Bank 9
000h
07Fh
080h
0FFh
100h
1FFh
200h
FFh
00h
2FFh
300h
FFh
00h
3FFh
400h
FFh
00h
4FFh
500h
FFh
00h
5FFh
600h
FFh
00h
6FFh
700h
7FFh
800h
FFh
00h
FFh
00h
Unused
Read 00h
FFh
00h
AFFh
B00h
FFh
00h
BFFh
C00h
FFh
Bank 13 00h
CFFh
D00h
FFh
00h
DFFh
E00h
Bank 12
Bank 14
The second 128 bytes are
Special Function Registers
(from Bank 15).
FFh
00h
Unused
FFh
SFR
Bank 15
When ‘a’ = 1:
The BSR specifies the Bank
used by the instruction.
Access Bank
Access RAM Low
00h
7Fh
Access RAM High 80h
(SFRs)
FFh
8FFh
900h
9FFh
A00h
Bank 11
The first 128 bytes are
general purpose RAM
(from Bank 0).
GPR
FFh
00h
FFh
00h
Bank 10
The BSR is ignored and the
Access Bank is used.
EFFh
F00h
F7Fh
F80h
FFFh
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 5-6:
DATA MEMORY MAP FOR PIC18F2520/4520 DEVICES
BSR<3:0>
= 0000
= 0001
= 0010
= 0011
= 0100
= 0101
= 0110
= 0111
= 1000
= 1001
= 1010
= 1011
= 1100
= 1101
= 1110
= 1111
When ‘a’ = 0:
Data Memory Map
00h
Access RAM
FFh
00h
GPR
Bank 0
GPR
Bank 1
Bank 2
Bank 3
Bank 4
Bank 5
Bank 6
Bank 7
Bank 8
Bank 9
Bank 10
000h
07Fh
080h
0FFh
100h
1FFh
200h
FFh
00h
2FFh
300h
GPR
3FFh
400h
FFh
00h
The BSR specifies the Bank
used by the instruction.
GPR
FFh
00h
5FFh
600h
FFh
00h
6FFh
700h
FFh
00h
7FFh
800h
FFh
00h
8FFh
900h
FFh
00h
Unused
Read 00h
FFh
Bank 13 00h
CFFh
D00h
FFh
00h
DFFh
E00h
FFh
00h
Unused
FFh
SFR
Bank 15
Access Bank
Access RAM Low
00h
7Fh
Access RAM High 80h
(SFRs)
FFh
9FFh
A00h
BFFh
C00h
© 2008 Microchip Technology Inc.
When ‘a’ = 1:
4FFh
500h
FFh
00h
FFh
00h
Bank 14
The second 128 bytes are
Special Function Registers
(from Bank 15).
GPR
AFFh
B00h
Bank 12
The first 128 bytes are
general purpose RAM
(from Bank 0).
GPR
FFh
00h
FFh
00h
Bank 11
The BSR is ignored and the
Access Bank is used.
EFFh
F00h
F7Fh
F80h
FFFh
DS39631E-page 61
PIC18F2420/2520/4420/4520
FIGURE 5-7:
USE OF THE BANK SELECT REGISTER (DIRECT ADDRESSING)
BSR(1)
7
0
0
0
0
0
0
0
Bank Select(2)
1
1
000h
Data Memory
Bank 0
100h
Bank 1
200h
300h
Bank 2
00h
7
FFh
00h
1
From Opcode(2)
1
1
1
1
1
0
1
1
FFh
00h
FFh
00h
Bank 3
through
Bank 13
E00h
Bank 14
F00h
FFFh
Note 1:
2:
5.3.2
Bank 15
FFh
00h
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.
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 128 bytes of
memory (00h-7Fh) in Bank 0 and the last 128 bytes of
memory (80h-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 (Figure 5-5).
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’,
DS39631E-page 62
however, the instruction is forced to use the Access
Bank address map; the current value of the BSR is
ignored entirely.
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 80h and
above, this means that users can evaluate and operate
on SFRs more efficiently. The Access RAM below 80h
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”.
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.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 half of Bank 15 (F80h to FFFh). A list of these
registers is given in Table 5-1 and Table 5-2.
TABLE 5-1:
Address
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.
SPECIAL FUNCTION REGISTER MAP FOR PIC18F2420/2520/4420/4520 DEVICES
Name
Address
Name
INDF2(1)
Address
Name
Address
Name
FFFh
TOSU
FDFh
FBFh
CCPR1H
F9Fh
IPR1
FFEh
TOSH
FDEh POSTINC2(1)
FBEh
CCPR1L
F9Eh
PIR1
FFDh
TOSL
FDDh POSTDEC2(1)
FBDh
CCP1CON
F9Dh
PIE1
FFCh
STKPTR
FDCh
PREINC2(1)
FBCh
CCPR2H
F9Ch
—(2)
FFBh
PCLATU
FDBh
PLUSW2(1)
FBBh
CCPR2L
F9Bh
OSCTUNE
FFAh
PCLATH
FDAh
FSR2H
FBAh
CCP2CON
F9Ah
—(2)
FF9h
PCL
FD9h
FSR2L
FB9h
—(2)
F99h
—(2)
FF8h
TBLPTRU
FD8h
STATUS
FB8h
BAUDCON
F98h
—(2)
FF7h
TBLPTRH
FD7h
TMR0H
FB7h PWM1CON(3)
F97h
—(2)
F96h
TRISE(3)
FF6h
TBLPTRL
FD6h
TMR0L
FB6h
ECCP1AS(3)
FF5h
TABLAT
FD5h
T0CON
FB5h
CVRCON
F95h
TRISD(3)
FD4h
—(2)
FB4h
CMCON
F94h
TRISC
FF4h
PRODH
FF3h
PRODL
FD3h
OSCCON
FB3h
TMR3H
F93h
TRISB
FF2h
INTCON
FD2h
HLVDCON
FB2h
TMR3L
F92h
TRISA
FF1h
INTCON2
FD1h
WDTCON
FB1h
T3CON
F91h
—(2)
FF0h
INTCON3
FD0h
RCON
FB0h
SPBRGH
F90h
—(2)
FEFh
INDF0(1)
FCFh
TMR1H
FAFh
SPBRG
F8Fh
—(2)
FEEh
POSTINC0(1)
FCEh
TMR1L
FAEh
RCREG
F8Eh
—(2)
FEDh POSTDEC0(1)
FCDh
T1CON
FADh
TXREG
F8Dh
LATE(3)
FCCh
TMR2
FACh
TXSTA
F8Ch
LATD(3)
FECh
PREINC0(1)
FEBh
PLUSW0(1)
FCBh
PR2
FABh
RCSTA
F8Bh
LATC
FEAh
FSR0H
FCAh
T2CON
FAAh
—(2)
F8Ah
LATB
FE9h
FSR0L
FC9h
SSPBUF
FA9h
EEADR
F89h
LATA
FE8h
WREG
FC8h
SSPADD
FA8h
EEDATA
F88h
—(2)
FE7h
INDF1(1)
FC7h
SSPSTAT
FA7h
EECON2(1)
F87h
—(2)
FE6h
POSTINC1(1)
FC6h
SSPCON1
FA6h
EECON1
F86h
—(2)
FE5h POSTDEC1(1)
FC5h
SSPCON2
FA5h
—(2)
F85h
—(2)
F84h
PORTE(3)
FE4h
PREINC1(1)
FC4h
ADRESH
FA4h
—(2)
FE3h
PLUSW1(1)
FC3h
ADRESL
FA3h
—(2)
F83h
PORTD(3)
FE2h
FSR1H
FC2h
ADCON0
FA2h
IPR2
F82h
PORTC
FE1h
FSR1L
FC1h
ADCON1
FA1h
PIR2
F81h
PORTB
FE0h
BSR
FC0h
ADCON2
FA0h
PIE2
F80h
PORTA
Note 1:
2:
3:
This is not a physical register.
Unimplemented registers are read as ‘0’.
This register is not available on 28-pin devices.
© 2008 Microchip Technology Inc.
DS39631E-page 63
PIC18F2420/2520/4420/4520
TABLE 5-2:
File Name
PIC18F2420/2520/4420/4520 REGISTER FILE SUMMARY
Bit 7
Bit 6
Bit 5
—
—
—
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Details
on page:
---0 0000
49, 54
TOSH
Top-of-Stack High Byte (TOS<15:8>)
0000 0000
49, 54
TOSL
Top-of-Stack Low Byte (TOS<7:0>)
0000 0000
49, 54
00-0 0000
49, 55
---0 0000
49, 54
TOSU
STKPTR
STKFUL
STKUNF
—
PCLATU
—
—
—
Top-of-Stack Upper Byte (TOS<20:16>)
Value on
POR, BOR
SP4
SP3
SP2
SP1
SP0
Holding Register for PC<20:16>
PCLATH
Holding Register for PC<15:8>
0000 0000
49, 54
PCL
PC Low Byte (PC<7:0>)
0000 0000
49, 54
--00 0000
49, 76
TBLPTRU
—
—
bit 21
Program Memory Table Pointer Upper Byte (TBLPTR<20:16>)
TBLPTRH
Program Memory Table Pointer High Byte (TBLPTR<15:8>)
0000 0000
49, 76
TBLPTRL
Program Memory Table Pointer Low Byte (TBLPTR<7:0>)
0000 0000
49, 76
TABLAT
Program Memory Table Latch
0000 0000
49, 76
PRODH
Product Register High Byte
xxxx xxxx
49, 89
PRODL
Product Register Low Byte
xxxx xxxx
49, 89
INTCON
GIE/GIEH
PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
0000 000x
49, 93
INTCON2
RBPU
INTEDG0
INTEDG1
INTEDG2
—
TMR0IP
—
RBIP
1111 -1-1
49, 94
INT2IP
INT1IP
—
INT2IE
INT1IE
—
INT2IF
INT1IF
11-0 0-00
49, 95
N/A
49, 69
INTCON3
INDF0
Uses contents of FSR0 to address data memory – value of FSR0 not changed (not a physical register)
POSTINC0
Uses contents of FSR0 to address data memory – value of FSR0 post-incremented (not a physical register)
N/A
49, 69
POSTDEC0
Uses contents of FSR0 to address data memory – value of FSR0 post-decremented (not a physical register)
N/A
49, 69
PREINC0
Uses contents of FSR0 to address data memory – value of FSR0 pre-incremented (not a physical register)
N/A
49, 69
PLUSW0
Uses contents of FSR0 to address data memory – value of FSR0 pre-incremented (not a physical register) –
value of FSR0 offset by W
N/A
49, 69
FSR0H
---- 0000
49, 69
FSR0L
Indirect Data Memory Address Pointer 0 Low Byte
—
—
—
—
Indirect Data Memory Address Pointer 0 High Byte
xxxx xxxx
49, 69
WREG
Working Register
xxxx xxxx
49
INDF1
Uses contents of FSR1 to address data memory – value of FSR1 not changed (not a physical register)
N/A
49, 69
POSTINC1
Uses contents of FSR1 to address data memory – value of FSR1 post-incremented (not a physical register)
N/A
49, 69
POSTDEC1
Uses contents of FSR1 to address data memory – value of FSR1 post-decremented (not a physical register)
N/A
49, 69
PREINC1
Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register)
N/A
49, 69
PLUSW1
Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register) –
value of FSR1 offset by W
N/A
49, 69
---- 0000
50, 69
xxxx xxxx
50, 69
FSR1H
—
FSR1L
—
—
—
Indirect Data Memory Address Pointer 1 High Byte
Indirect Data Memory Address Pointer 1 Low Byte
BSR
—
INDF2
—
—
—
Bank Select Register
Uses contents of FSR2 to address data memory – value of FSR2 not changed (not a physical register)
---- 0000
50, 59
N/A
50, 69
POSTINC2
Uses contents of FSR2 to address data memory – value of FSR2 post-incremented (not a physical register)
N/A
50, 69
POSTDEC2
Uses contents of FSR2 to address data memory – value of FSR2 post-decremented (not a physical register)
N/A
50, 69
PREINC2
Uses contents of FSR2 to address data memory – value of FSR2 pre-incremented (not a physical register)
N/A
50, 69
PLUSW2
Uses contents of FSR2 to address data memory – value of FSR2 pre-incremented (not a physical register) –
value of FSR2 offset by W
N/A
50, 69
---- 0000
50, 69
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:
—
—
—
N
OV
Z
DC
C
xxxx xxxx
50, 69
---x xxxx
50, 67
x = unknown, u = unchanged, — = unimplemented, q = value depends on condition. Shaded cells are unimplemented, read as ‘0’.
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 configurations; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in
INTOSC 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’.
DS39631E-page 64
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 5-2:
File Name
PIC18F2420/2520/4420/4520 REGISTER FILE SUMMARY (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
50, 125
TMR0L
Timer0 Register Low Byte
xxxx xxxx
50, 125
50, 123
T0CON
TMR0ON
T08BIT
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
1111 1111
OSCCON
IDLEN
IRCF2
IRCF1
IRCF0
OSTS
IOFS
SCS1
SCS0
0100 q000
30, 50
HLVDCON
VDIRMAG
—
IRVST
HLVDEN
HLVDL3
HLVDL2
HLVDL1
HLVDL0
0-00 0101
50, 245
WDTCON
—
—
—
—
—
—
—
SWDTEN
--- ---0
50, 259
—
RI
TO
PD
POR
BOR
0q-1 11q0
42, 48,
102
RCON
IPEN
SBOREN
(1)
TMR1H
Timer1 Register High Byte
xxxx xxxx
50, 132
TMR1L
Timer1 Register Low Bytes
xxxx xxxx
50, 132
0000 0000
50, 127
50, 134
T1CON
RD16
T1RUN
T1CKPS1
T1CKPS0
T1OSCEN
T1SYNC
TMR1CS
TMR1ON
TMR2
Timer2 Register
0000 0000
PR2
Timer2 Period Register
1111 1111
50, 134
-000 0000
50, 133
xxxx xxxx
50, 169,
170
T2CON
—
T2OUTPS3
T2OUTPS2
T2OUTPS1
T2OUTPS0
TMR2ON
T2CKPS1
T2CKPS0
SSPBUF
MSSP Receive Buffer/Transmit Register
SSPADD
MSSP Address Register in I2C™ Slave Mode. MSSP Baud Rate Reload Register in I2C Master Mode.
0000 0000
50, 170
SSPSTAT
SMP
CKE
D/A
P
S
R/W
UA
BF
0000 0000
50, 162,
171
SSPCON1
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
0000 0000
50, 163,
172
GCEN
ACKSTAT
ACKDT
ACKEN
RCEN
PEN
RSEN
SEN
SSPCON2
0000 0000
50, 173
ADRESH
A/D Result Register High Byte
xxxx xxxx
51, 232
ADRESL
A/D Result Register Low Byte
xxxx xxxx
51, 232
ADCON0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
--00 0000
51, 223
ADCON1
—
—
VCFG1
VCFG0
PCFG3
PCFG2
PCFG1
PCFG0
--00 0qqq
51, 224
ADFM
—
ACQT2
ACQT1
ACQT0
ADCS2
ADCS1
ADCS0
ADCON2
0-00 0000
51, 225
CCPR1H
Capture/Compare/PWM Register 1 High Byte
xxxx xxxx
51, 140
CCPR1L
Capture/Compare/PWM Register 1 Low Byte
xxxx xxxx
51, 140
0000 0000
51, 139,
147
51, 140
CCP1CON
P1M1(2)
P1M0(2)
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
51, 140
--00 0000
51, 139
CCP2CON
—
BAUDCON
ABDOVF
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
0100 0-00
51, 204
PWM1CON
PRSEN
PDC6(2)
PDC5(2)
PDC4(2)
PDC3(2)
PDC2(2)
PDC1(2)
PDC0(2)
0000 0000
51, 156
ECCP1AS
ECCPASE
ECCPAS2
ECCPAS1
ECCPAS0
PSSAC1
PSSAC0
PSSBD1(2)
PSSBD0(2) 0000 0000
51, 157
CVRCON
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
0000 0000
51, 239
CMCON
C2OUT
C1OUT
C2INV
C1INV
CIS
CM2
CM1
CM0
0000 0111
51, 233
—
DC2B1
DC2B0
CCP2M3
CCP2M2
CCP2M1
CCP2M0
TMR3H
Timer3 Register High Byte
xxxx xxxx
51, 137
TMR3L
Timer3 Register Low Byte
xxxx xxxx
51, 137
0000 0000
51, 135
T3CON
RD16
Legend:
Note 1:
2:
3:
4:
5:
T3CCP2
T3CKPS1
T3CKPS0
T3CCP1
T3SYNC
TMR3CS
TMR3ON
x = unknown, u = unchanged, — = unimplemented, q = value depends on condition. Shaded cells are unimplemented, read as ‘0’.
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 configurations; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in
INTOSC 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’.
© 2008 Microchip Technology Inc.
DS39631E-page 65
PIC18F2420/2520/4420/4520
TABLE 5-2:
File Name
PIC18F2420/2520/4420/4520 REGISTER FILE SUMMARY (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
51, 206
SPBRG
EUSART Baud Rate Generator Register Low Byte
0000 0000
51, 206
RCREG
EUSART Receive Register
0000 0000
51, 213
TXREG
EUSART Transmit Register
0000 0000
51, 211
TXSTA
RCSTA
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
0000 0010
51, 202
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
51, 203
EEADR
EEPROM Address Register
0000 0000 51, 74, 83
EEDATA
EEPROM Data Register
0000 0000 51, 74, 83
EECON2
EEPROM Control Register 2 (not a physical register)
0000 0000 51, 74, 83
EECON1
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
xx-0 x000 51, 75, 84
IPR2
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
11-1 1111
52, 101
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
00-0 0000
52, 97
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
00-0 0000
52, 99
IPR1
PSPIP(2)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
1111 1111
52, 100
52, 96
PIR1
PSPIF(2)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
PIE1
PSPIE(2)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
52, 98
OSCTUNE
INTSRC
PLLEN(3)
—
TUN4
TUN3
TUN2
TUN1
TUN0
0q-0 0000
27, 52
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
TRISE(2)
0000 -111
52, 118
PORTD Data Direction Register
1111 1111
52, 114
TRISC
PORTC Data Direction Register
1111 1111
52, 111
TRISB
PORTB Data Direction Register
1111 1111
52, 108
1111 1111
52, 105
---- -xxx
52, 117
52, 114
TRISD(2)
TRISA
TRISA7(5)
TRISA6(5)
LATE(2)
—
—
PORTA Data Direction Register
—
—
—
PORTE Data Latch Register
(Read and Write to Data Latch)
LATD(2)
PORTD Data Latch Register (Read and Write to Data Latch)
xxxx xxxx
LATC
PORTC Data Latch Register (Read and Write to Data Latch)
xxxx xxxx
52, 111
LATB
PORTB Data Latch Register (Read and Write to Data Latch)
xxxx xxxx
52, 108
xxxx xxxx
52, 105
LATA7(5)
LATA6(5)
—
—
—
—
RE3(4)
RE2(2)
RE1(2)
RE0(2)
---- xxxx
52, 117
PORTD(2)
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
xxxx xxxx
52, 114
PORTC
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
xxxx xxxx
52, 111
PORTB
RB7
RB6
RB5
RB4
RB3
RB2
RB1
RB0
xxxx xxxx
52, 108
RA7(5)
RA6(5)
RA5
RA4
RA3
RA2
RA1
RA0
xx0x 0000
52, 105
LATA
PORTE
PORTA
Legend:
Note 1:
2:
3:
4:
5:
PORTA Data Latch Register (Read and Write to Data Latch)
x = unknown, u = unchanged, — = unimplemented, q = value depends on condition. Shaded cells are unimplemented, read as ‘0’.
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 configurations; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in
INTOSC 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’.
DS39631E-page 66
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 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
R/W-x
OV
Z
R/W-x
R/W-x
(1)
C(2)
DC
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
N: Negative bit
This bit is used for signed arithmetic (2’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 (2’s complement). It indicates an overflow of the 7-bit magnitude
which causes the sign bit (bit 7) 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(1)
For ADDWF, ADDLW, SUBLW and SUBWF instructions:
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(2)
For ADDWF, ADDLW, SUBLW and SUBWF instructions:
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:
2:
For borrow, the polarity is reversed. A subtraction is executed by adding the 2’s complement of the second
operand. For rotate (RRF, RLF) instructions, this bit is loaded with either bit 4 or bit 3 of the source register.
For borrow, the polarity is reversed. A subtraction is executed by adding the 2’s complement of the second
operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high or low-order bit of the
source register.
© 2008 Microchip Technology Inc.
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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 to be read or written
to. Since the FSRs are themselves located in RAM as
Special Function 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
;
;
;
FSR0H, 1; All
;
NEXT
;
;
Clear INDF
register then
inc pointer
done with
Bank1?
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.
DS39631E-page 68
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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. The four upper
bits of the FSRnH register are not used so each FSR
pair holds a 12-bit value. This represents a value that
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 that cannot be indirectly
read or written to. Accessing these registers actually
accesses the associated FSR register pair, but also
performs a specific action on it stored value. They are:
• POSTDEC: accesses the FSR value, then
automatically decrements it by 1 afterwards
• POSTINC: accesses the FSR value, then
automatically increments it by 1 afterwards
• PREINC: increments the FSR value by 1, then
uses it 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 new value 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.
In this context, accessing an INDF register uses the
value in the FSR registers without changing them. Similarly, accessing a PLUSW register gives the FSR value
offset by that in the W register; neither value is actually
changed in the operation. Accessing the other virtual
registers changes the value of the FSR registers.
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 5-8:
FSR Registers and POSTINC,
POSTDEC, PREINC and PLUSW
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.).
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
...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 2
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
FFFh
Bank 15
Data Memory
© 2008 Microchip Technology Inc.
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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 INDF2
or POSTDEC2 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.
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 remains unchanged.
DS39631E-page 70
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 in shown in Figure 5-9.
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”.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 5-9:
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 060h to 07Fh
(Bank 0) and F80h to FFFh
(Bank 15) of data memory.
000h
Locations below 60h are not
available in this addressing
mode.
F00h
060h
080h
Bank 0
100h
00h
Bank 1
through
Bank 14
60h
80h
Valid range
for ‘f’
FFh
Access RAM
Bank 15
F80h
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
Bank 0
080h
100h
001001da ffffffff
Bank 1
through
Bank 14
FSR2H
FSR2L
F00h
Bank 15
F80h
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
Bank 0
080h
100h
Bank 1
through
Bank 14
001001da ffffffff
F00h
Bank 15
F80h
SFRs
FFFh
Data Memory
© 2008 Microchip Technology Inc.
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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 half of Bank 0, this mode
maps the contents from Bank 0 and 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 5-10.
FIGURE 5-10:
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
05Fh
07Fh
Bank 0
100h
120h
17Fh
200h
Bank 0 addresses below
5Fh can still be addressed
by using the BSR.
Bank 1
Window
Bank 1
00h
Bank 1 “Window”
5Fh
Locations in Bank 0 from
060h to 07Fh are mapped,
as usual, to the middle half
of the Access Bank.
Special Function Registers
at F80h through FFFh are
mapped to 80h through
FFh, as usual.
Bank 0
Bank 0
Bank 2
through
Bank 14
7Fh
80h
SFRs
FFh
Access Bank
F00h
Bank 15
F80h
FFFh
SFRs
Data Memory
DS39631E-page 72
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6.0
FLASH PROGRAM MEMORY
6.1
Table Reads and Table Writes
The Flash program memory is readable, writable and
erasable during normal operation over the entire VDD
range.
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:
A read from program memory is executed on one byte
at a time. A write to program memory is executed on
blocks of 32 bytes at a time. Program memory is
erased in blocks of 64 bytes at a time. A bulk erase
operation may not be issued from user code.
• Table Read (TBLRD)
• Table Write (TBLWT)
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.
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.
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).
Table read operations retrieve data from program
memory and places it into the data RAM space.
Figure 6-1 shows the operation of a table read with
program memory and data RAM.
Table write operations store data from the data memory
space into holding registers in program memory. 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. A table block
containing data, rather than program instructions, is not
required to be word aligned. Therefore, a table block 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.
FIGURE 6-1:
TABLE READ OPERATION
Instruction: TBLRD*
Program Memory
Table Pointer(1)
TBLPTRU
TBLPTRH
Table Latch (8-bit)
TBLPTRL
TABLAT
Program Memory
(TBLPTR)
Note 1: The Table Pointer register points to a byte in program memory.
© 2008 Microchip Technology Inc.
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FIGURE 6-2:
TABLE WRITE OPERATION
Instruction: TBLWT*
Program Memory
Holding Registers
Table Pointer(1)
TBLPTRU
TBLPTRH
Table Latch (8-bit)
TBLPTRL
TABLAT
Program Memory
(TBLPTR)
Note1: The Table Pointer actually points to one of 32 holding registers, the address of which is determined by
TBLPTRL<4:0>. The process for physically writing data 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
clear, any subsequent operations will operate on the
data EEPROM memory. When 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 set,
subsequent operations will operate on Configuration
registers regardless of EEPGD (see Section 23.0
“Special Features of the CPU”). When clear, memory
selection access is determined by EEPGD.
DS39631E-page 74
The FREE bit, when set, will allow a program memory
erase operation. When FREE is set, the 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.
On power-up, the WREN bit is clear. The WRERR bit is
set in 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 bit
cannot be cleared, only set, in software; it is cleared in
hardware at the completion of the write operation.
Note:
The EEIF interrupt flag bit (PIR2<4>) is set
when the write is complete. It must be
cleared in software.
© 2008 Microchip Technology Inc.
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REGISTER 6-1:
R/W-x
EECON1: EEPROM CONTROL REGISTER 1
R/W-x
EEPGD
U-0
CFGS
—
R/W-0
FREE
R/W-x
WRERR
(1)
R/W-0
R/S-0
R/S-0
WREN
WR
RD
bit 7
bit 0
Legend:
S = Settable bit (cannot be cleared in software)
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
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 Erase Enable bit
1 = Erase the program memory row 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) in 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 in hardware. The RD bit can only
be set (not cleared) in 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.
© 2008 Microchip Technology Inc.
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6.2.2
TABLAT – TABLE LATCH REGISTER
6.2.4
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
TBLPTR is used in reads, writes and erases of the
Flash program memory.
When a TBLRD is executed, all 22 bits of the TBLPTR
determine which byte is read from program memory
into TABLAT.
TBLPTR – TABLE POINTER
REGISTER
When a TBLWT is executed, the five LSbs of the Table
Pointer register (TBLPTR<4:0>) determine which of
the 32 program memory holding registers is written to.
When the timed write to program memory begins (via
the WR bit), the 16 MSbs of the TBLPTR
(TBLPTR<21:6>) determine which program memory
block of 32 bytes is written to. For more detail, see
Section 6.5 “Writing to Flash Program Memory”.
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 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.
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 6-1. These operations on the TBLPTR only affect
the low-order 21 bits.
TABLE 6-1:
TABLE POINTER BOUNDARIES
Figure 6-3 describes the relevant boundaries of
TBLPTR based on Flash program memory operations.
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
TBLPTRL
0
TABLE ERASE
TBLPTR<21:6>
TABLE WRITE – TBLPTR<21:5>
TABLE READ – TBLPTR<21:0>
DS39631E-page 76
© 2008 Microchip Technology Inc.
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6.3
Reading the Flash Program
Memory
The TBLRD instruction is used to retrieve data from
program memory and places it into data RAM. Table
reads from program memory are performed one byte at
a time.
FIGURE 6-4:
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.
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.
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
© 2008 Microchip Technology Inc.
; read into TABLAT and increment
; get data
; read into TABLAT and increment
; get data
DS39631E-page 77
PIC18F2420/2520/4420/4520
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.
TBLPTR<5:0> are ignored.
6.4.1
The sequence of events for erasing a block of internal
program memory location is:
1.
2.
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.
3.
4.
5.
6.
For protection, the write initiate sequence for EECON2
must be used.
7.
A long write is necessary for erasing the internal Flash.
Instruction execution is halted while in a long write
cycle. The long write will be terminated by the internal
programming timer.
EXAMPLE 6-2:
FLASH PROGRAM MEMORY
ERASE SEQUENCE
8.
Load Table Pointer register with address of row
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 row erase
cycle.
The CPU will stall for duration of the erase
(about 2 ms using internal timer).
Re-enable interrupts.
ERASING A FLASH PROGRAM MEMORY ROW
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_ROW
Required
Sequence
DS39631E-page 78
EEPGD
CFGS
WREN
FREE
GIE
point to Flash program memory
access Flash program memory
enable write to memory
enable Row Erase operation
disable interrupts
; write 55h
WR
GIE
; write 0AAh
; start erase (CPU stall)
; re-enable interrupts
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
6.5
Writing to Flash Program Memory
The minimum programming block is 16 words or
32 bytes. 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 32 holding registers used by the table writes for
programming.
Since the Table Latch (TABLAT) is only a single byte,
the TBLWT instruction may need to be executed
32 times for each programming operation. All of the
table write operations will essentially be short writes
because only the holding registers are written. At the
end of updating the 32 holding registers, the EECON1
register must be written to in order to start the
programming operation with a long write.
FIGURE 6-5:
The long write is necessary for programming the internal Flash. Instruction execution is halted while in 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 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 32 holding registers
before executing a write operation.
TABLE WRITES TO FLASH PROGRAM MEMORY
TABLAT
Write Register
8
8
TBLPTR = xxxxx0
TBLPTR = xxxxx1
Holding Register
8
TBLPTR = xxxx3F
TBLPTR = xxxxx2
Holding Register
8
Holding Register
Holding Register
Program Memory
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 row erase procedure.
Load Table Pointer register with address of first
byte being written.
Write the 32 bytes 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.
© 2008 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. Verify the memory (table read).
This procedure will require about 6 ms to update one
row of 64 bytes 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 32 bytes in
the holding register.
DS39631E-page 79
PIC18F2420/2520/4420/4520
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
TBLRD*+
MOVF
MOVWF
DECFSZ
BRA
TABLAT, W
POSTINC0
COUNTER
READ_BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
DATA_ADDR_HIGH
FSR0H
DATA_ADDR_LOW
FSR0L
NEW_DATA_LOW
POSTINC0
NEW_DATA_HIGH
INDF0
; number of bytes in erase block
; 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
; point to buffer
; update buffer word
ERASE_BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BCF
BSF
BSF
BCF
MOVLW
Required
MOVWF
Sequence
MOVLW
MOVWF
BSF
BSF
TBLRD*MOVLW
MOVWF
MOVLW
MOVWF
WRITE_BUFFER_BACK
MOVLW
MOVWF
WRITE_BYTE_TO_HREGS
MOVFF
MOVWF
TBLWT+*
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
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
;
;
;
;
;
point to Flash program memory
access Flash program memory
enable write to memory
enable Row Erase operation
disable interrupts
; write 55h
;
;
;
;
;
write 0AAh
start erase (CPU stall)
re-enable interrupts
dummy read decrement
point to buffer
D’32
COUNTER
; number of bytes in holding register
POSTINC0, WREG
TABLAT
;
;
;
;
;
DECFSZ COUNTER
BRA
WRITE_WORD_TO_HREGS
DS39631E-page 80
; load TBLPTR with the base
; address of the memory block
get low byte of buffer data
present data to table latch
write data, perform a short write
to internal TBLWT holding register.
loop until buffers are full
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
PROGRAM_MEMORY
BSF
BCF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BSF
BCF
Required
Sequence
6.5.2
EECON1,
EECON1,
EECON1,
INTCON,
55h
EECON2
0AAh
EECON2
EECON1,
INTCON,
EECON1,
EEPGD
CFGS
WREN
GIE
;
;
;
;
point to Flash program memory
access Flash program memory
enable write to memory
disable interrupts
; write 55h
;
;
;
;
WR
GIE
WREN
write 0AAh
start program (CPU stall)
re-enable interrupts
disable write to memory
6.5.4
WRITE VERIFY
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
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 user can check the WRERR bit
and rewrite the location(s) as needed.
TABLE 6-2:
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 23.5 “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
49
TBLPTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>)
49
TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>)
49
TABLAT
49
Program Memory Table Latch
INTCON
GIE/GIEH PEIE/GIEL TMR0IE
EECON2
EEPROM Control Register 2 (not a physical register)
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
51
EECON1
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
51
IPR2
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
© 2008 Microchip Technology Inc.
DS39631E-page 81
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 82
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
7.0
DATA EEPROM MEMORY
The data EEPROM is a nonvolatile memory array,
separate from the data RAM and program memory, that
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.
Five SFRs are used to read and write to the data
EEPROM as well as the program memory. They are:
•
•
•
•
EECON1
EECON2
EEDATA
EEADR
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 register
holds 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 chip
to chip. Please refer to parameter D122 (Table 26-1 in
Section 26.0 “Electrical Characteristics”) for exact
limits.
7.1
EEADR Register
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).
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.
© 2008 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 clear, operations will
access the data EEPROM memory. When 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 set, subsequent operations
access Configuration registers. When CFGS 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 in 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 in software. It is only cleared
in hardware at the completion of the write operation.
Note:
The EEIF interrupt flag bit (PIR2<4>) is set
when the write is complete. It must be
cleared in 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.
DS39631E-page 83
PIC18F2420/2520/4420/4520
REGISTER 7-1:
EECON1: EEPROM CONTROL REGISTER 1
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(1)
WREN
WR
RD
bit 7
bit 0
Legend:
S = Settable bit (cannot be cleared in software)
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
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 Erase Enable bit
1 = Erase the program memory row 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) in 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 in hardware. The RD bit can only
be set (not cleared) in 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.
DS39631E-page 84
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 (EECON1<7>) and then set control bit, RD
(EECON1<0>). 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
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.
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.
EXAMPLE 7-1:
MOVLW
MOVWF
BCF
BCF
BSF
MOVF
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 in 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.
7.5
Write Verify
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.
DATA EEPROM READ
DATA_EE_ADDR
EEADR
EECON1, EEPGD
EECON1, CFGS
EECON1, RD
EEDATA, W
EXAMPLE 7-2:
Required
Sequence
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.
;
;
;
;
;
;
Data Memory Address to read
Point to DATA memory
Access EEPROM
EEPROM Read
W = EEDATA
DATA EEPROM WRITE
MOVLW
MOVWF
MOVLW
MOVWF
BCF
BCF
BSF
DATA_EE_ADDR
EEADR
DATA_EE_DATA
EEDATA
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
;
;
;
;
;
;
;
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BSF
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
INTCON, GIE
;
;
;
;
;
;
;
BCF
EECON1, WREN
; User code execution
; Disable writes on write complete (EEIF set)
© 2008 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
DS39631E-page 85
PIC18F2420/2520/4420/4520
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).
7.8
Using the Data EEPROM
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). Frequently changing values will typically be
updated more often than specification D124. If this is
not the case, 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:
If data EEPROM is only used to store
constants and/or data that changes rarely,
an array refresh is likely not required. See
specification D124.
The write initiate sequence and the WREN bit together
help prevent an accidental write during brown-out,
power glitch or software malfunction.
EXAMPLE 7-3:
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
DS39631E-page 86
;
;
;
;
;
;
;
;
;
;
;
;
;
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 7-1:
Name
INTCON
REGISTERS ASSOCIATED WITH DATA EEPROM MEMORY
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
GIE/GIEH
PEIE/GIEL
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
Reset
Values
on page
49
EEADR
EEPROM Address Register
51
EEDATA
EEPROM Data Register
51
EECON2
EEPROM Control Register 2 (not a physical register)
51
EECON1
EEPGD
CFGS
—
FREE
WRERR
WREN
WR
RD
51
IPR2
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
© 2008 Microchip Technology Inc.
DS39631E-page 87
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 88
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 μs
27.6 μs
69 μs
1
100 ns
400 ns
1 μs
91
9.1 μs
36.4 μs
91 μs
6
600 ns
2.4 μs
6 μs
21
242
24.2 μs
96.8 μs
242 μs
28
28
2.8 μs
11.2 μs
28 μs
Without hardware multiply
52
254
25.4 μs
102.6 μs
254 μs
Hardware multiply
35
40
4.0 μs
16.0 μs
40 μs
© 2008 Microchip Technology Inc.
DS39631E-page 89
PIC18F2420/2520/4420/4520
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:
RES<3:0>
=
=
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:
RES<3:0> = 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.
DS39631E-page 90
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
:
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
9.0
INTERRUPTS
The PIC18F2420/2520/4420/4520 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 lowpriority interrupt vector is at 0018h. High-priority
interrupt events will interrupt any low-priority interrupts
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
The interrupt priority feature is enabled by setting the
IPEN bit (RCON<7>). When interrupt priority is
enabled, there are two bits which enable interrupts
globally. Setting the GIEH bit (INTCON<7>) enables all
interrupts that have the priority bit set (high priority).
Setting the GIEL bit (INTCON<6>) enables all
interrupts that have the priority bit cleared (low priority).
When the interrupt flag, enable bit and appropriate
global interrupt enable bit are set, the interrupt will vector immediately to address 0008h or 0018h, depending
on the priority bit setting. Individual interrupts can be
disabled through their corresponding enable bits.
© 2008 Microchip Technology Inc.
When the IPEN bit is cleared (default state), the
interrupt priority feature is disabled and interrupts are
compatible with PIC® mid-range devices. In Compatibility mode, the interrupt priority bits for each source
have no effect. INTCON<6> is the PEIE bit, which
enables/disables all peripheral interrupt sources.
INTCON<7> is the GIE bit, which enables/disables all
interrupt sources. All interrupts branch to address
0008h in Compatibility mode.
When an interrupt is responded to, the global interrupt
enable bit is cleared to disable further interrupts. If the
IPEN bit is cleared, this is the GIE bit. If interrupt priority
levels are used, this will be either the GIEH or GIEL bit.
High-priority interrupt sources can interrupt a lowpriority 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. The interrupt flag bits must be
cleared in software before re-enabling interrupts to
avoid recursive interrupts.
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 INTx pins or
the PORTB input change interrupt, the interrupt latency
will be three to four instruction cycles. The exact
latency is the same for one or two-cycle instructions.
Individual interrupt flag bits are set, regardless of the
status of their corresponding enable bit or the GIE bit.
Note:
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.
DS39631E-page 91
PIC18F2420/2520/4420/4520
FIGURE 9-1:
PIC18 INTERRUPT LOGIC
Wake-up if in
Idle or Sleep modes
TMR0IF
TMR0IE
TMR0IP
RBIF
RBIE
RBIP
INT0IF
INT0IE
Interrupt to CPU
Vector to Location
0008h
INT1IF
INT1IE
INT1IP
INT2IF
INT2IE
INT2IP
SSPIF
SSPIE
SSPIP
GIE/GIEH
ADIF
ADIE
ADIP
IPEN
IPEN
RCIF
RCIE
RCIP
PEIE/GIEL
IPEN
Additional Peripheral Interrupts
High-Priority Interrupt Generation
Low-Priority Interrupt Generation
SSPIF
SSPIE
SSPIP
Interrupt to CPU
Vector to Location
0018h
TMR0IF
TMR0IE
TMR0IP
ADIF
ADIE
ADIP
RBIF
RBIE
RBIP
RCIF
RCIE
RCIP
Additional Peripheral Interrupts
GIE/GIEH
PEIE/GIE
INT1IF
INT1IE
INT1IP
INT2IF
INT2IE
INT2IP
DS39631E-page 92
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
9.1
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(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
GIE/GIEH: Global Interrupt Enable bit
When IPEN = 0:
1 = Enables all unmasked interrupts
0 = Disables all interrupts
When IPEN = 1:
1 = Enables all high-priority interrupts
0 = Disables all interrupts
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 peripheral interrupts
0 = Disables all low-priority peripheral 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
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 in software)
0 = TMR0 register did not overflow
bit 1
INT0IF: INT0 External Interrupt Flag bit
1 = The INT0 external interrupt occurred (must be cleared in 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 in software)
0 = None of the RB<7:4> pins have changed state
Note 1:
A mismatch condition will continue to set this bit. Reading PORTB will end the mismatch condition and
allow the bit to be cleared.
© 2008 Microchip Technology Inc.
DS39631E-page 93
PIC18F2420/2520/4420/4520
REGISTER 9-2:
INTCON2: INTERRUPT CONTROL REGISTER 2
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
bit 7
RBPU: PORTB Pull-up Enable bit
1 = All PORTB pull-ups are disabled
0 = PORTB pull-ups are enabled by individual port latch values
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:
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.
DS39631E-page 94
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-3:
INTCON3: INTERRUPT CONTROL REGISTER 3
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 in 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 in 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.
© 2008 Microchip Technology Inc.
DS39631E-page 95
PIC18F2420/2520/4420/4520
9.2
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).
REGISTER 9-4:
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 (INTCON<7>).
2: User software should ensure the appropriate interrupt flag bits are cleared prior to
enabling an interrupt and after servicing
that interrupt.
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 in 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 in software)
0 = The A/D conversion is not complete
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 in software)
0 = Waiting to transmit/receive
bit 2
CCP1IF: CCP1 Interrupt Flag bit
Capture mode:
1 = A TMR1 register capture occurred (must be cleared in software)
0 = No TMR1 register capture occurred
Compare mode:
1 = A TMR1 register compare match occurred (must be cleared in 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 in software)
0 = No TMR2 to PR2 match occurred
bit 0
TMR1IF: TMR1 Overflow Interrupt Flag bit
1 = TMR1 register overflowed (must be cleared in software)
0 = TMR1 register did not overflow
Note 1:
This bit is unimplemented on 28-pin devices and will read as ‘0’.
DS39631E-page 96
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-5:
PIR2: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 2
R/W-0
R/W-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
OSCFIF
CMIF
—
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 INTOSC (must be cleared in software)
0 = Device clock operating
bit 6
CMIF: Comparator Interrupt Flag bit
1 = Comparator input has changed (must be cleared in software)
0 = Comparator input has not changed
bit 5
Unimplemented: Read as ‘0’
bit 4
EEIF: Data EEPROM/Flash Write Operation Interrupt Flag bit
1 = The write operation is complete (must be cleared in 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 in software)
0 = No bus collision occurred
bit 2
HLVDIF: High/Low-Voltage Detect Interrupt Flag bit
1 = A high/low-voltage condition occurred (direction determined by VDIRMAG bit, HLVDCON<7>)
0 = A high/low-voltage condition has not occurred
bit 1
TMR3IF: TMR3 Overflow Interrupt Flag bit
1 = TMR3 register overflowed (must be cleared in 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 in software)
0 = No TMR1 register capture occurred
Compare mode:
1 = A TMR1 register compare match occurred (must be cleared in software)
0 = No TMR1 register compare match occurred
PWM mode:
Unused in this mode.
© 2008 Microchip Technology Inc.
DS39631E-page 97
PIC18F2420/2520/4420/4520
9.3
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:
R/W-0
PIE1: PERIPHERAL INTERRUPT ENABLE REGISTER 1
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
(1)
PSPIE
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
This bit is unimplemented on 28-pin devices and will read as ‘0’.
DS39631E-page 98
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-7:
PIE2: PERIPHERAL INTERRUPT ENABLE REGISTER 2
R/W-0
R/W-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
OSCFIE
CMIE
—
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
CMIE: Comparator Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 5
Unimplemented: Read as ‘0’
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: High/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
© 2008 Microchip Technology Inc.
x = Bit is unknown
DS39631E-page 99
PIC18F2420/2520/4420/4520
9.4
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:
R/W-1
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
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
(1)
PSPIP
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:
This bit is unimplemented on 28-pin devices and will read as ‘0’.
DS39631E-page 100
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-9:
IPR2: PERIPHERAL INTERRUPT PRIORITY REGISTER 2
R/W-1
R/W-1
U-0
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
OSCFIP
CMIP
—
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
CMIP: Comparator Interrupt Priority bit
1 = High priority
0 = Low priority
bit 5
Unimplemented: Read as ‘0’
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: High/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
© 2008 Microchip Technology Inc.
x = Bit is unknown
DS39631E-page 101
PIC18F2420/2520/4420/4520
9.5
The operation of the SBOREN bit and the Reset flag
bits is discussed in more detail in Section 4.1 “RCON
Register”.
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.
REGISTER 9-10:
RCON: RESET CONTROL REGISTER
R/W-0
R/W-1(1)
U-0
R/W-1
R-1
R-1
R/W-0(1)
R/W-0
IPEN
SBOREN
—
RI
TO
PD
POR
BOR
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
IPEN: Interrupt Priority Enable bit
1 = Enable priority levels on interrupts
0 = Disable priority levels on interrupts (PIC16CXXX 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 Timer 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(1)
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.
DS39631E-page 102
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
9.6
INTx Pin Interrupts
9.7
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, INTxIF, is set. This interrupt can be disabled by
clearing the corresponding enable bit, INTxIE. Flag bit,
INTxIF, must be cleared in 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 INTxIE
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
(INTCON3<6>) and INT2IP (INTCON3<7>). 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 (INTCON<5>). Interrupt priority for Timer0 is
determined by the value contained in the interrupt
priority bit, TMR0IP (INTCON2<2>). See Section 11.0
“Timer0 Module” for further details on the Timer0
module.
9.8
PORTB Interrupt-on-Change
An input change on PORTB<7:4> sets flag bit, RBIF
(INTCON<0>). The interrupt can be enabled/disabled
by setting/clearing enable bit, RBIE (INTCON<3>).
Interrupt priority for PORTB interrupt-on-change is
determined by the value contained in the interrupt
priority bit, RBIP (INTCON2<0>).
9.9
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 5.3
“Data Memory Organization”), 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:
MOVWF
MOVFF
MOVFF
;
; USER
;
MOVFF
MOVF
MOVFF
SAVING STATUS, WREG AND BSR REGISTERS IN RAM
W_TEMP
STATUS, STATUS_TEMP
BSR, BSR_TEMP
; W_TEMP is in virtual bank
; STATUS_TEMP located anywhere
; BSR_TMEP located anywhere
ISR CODE
BSR_TEMP, BSR
W_TEMP, W
STATUS_TEMP, STATUS
© 2008 Microchip Technology Inc.
; Restore BSR
; Restore WREG
; Restore STATUS
DS39631E-page 103
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 104
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
10.0
I/O PORTS
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 (Data Latch register)
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:
Reading the PORTA register reads the status of the
pins, whereas writing to it, will write to the port latch.
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 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’.
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 A/D Converter inputs is selected
by clearing or setting the control bits in the ADCON1
register (A/D Control Register 1).
Pins RA0 through RA5 may also be used as comparator
inputs or outputs by setting the appropriate bits in the
CMCON register. To use RA<3:0> as digital inputs, it is
also necessary to turn off the comparators.
GENERIC I/O PORT
OPERATION
RD LAT
Note:
Data
Bus
D
WR LAT
or Port
Q
I/O pin(1)
CK
Data Latch
D
WR TRIS
Q
CK
TRIS Latch
Input
Buffer
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 direction of the PORTA
pins, even when they are being used as analog inputs.
The user must ensure the bits in the TRISA register are
maintained set when using them as analog inputs.
EXAMPLE 10-1:
RD TRIS
CLRF
Q
D
CLRF
ENEN
RD Port
Note 1:
10.1
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.
I/O pins have diode protection to VDD and VSS.
MOVLW
MOVWF
MOVWF
MOVWF
MOVLW
PORTA, TRISA and LATA Registers
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., put the corresponding output driver in a
high-impedance mode). Clearing a TRISA bit (= 0) will
make the corresponding PORTA pin an output (i.e., put
the contents of the output latch on the selected pin).
© 2008 Microchip Technology Inc.
MOVWF
PORTA
;
;
;
LATA
;
;
;
07h
;
ADCON1 ;
07h
;
CMCON
;
0CFh
;
;
;
TRISA
;
;
INITIALIZING PORTA
Initialize PORTA by
clearing output
data latches
Alternate method
to clear output
data latches
Configure A/D
for digital inputs
Configure comparators
for digital input
Value used to
initialize data
direction
Set RA<3:0> as inputs
RA<5:4> as outputs
DS39631E-page 105
PIC18F2420/2520/4420/4520
TABLE 10-1:
PORTA I/O SUMMARY
Pin
RA0/AN0
RA1/AN1
RA2/AN2/
VREF-/CVREF
RA3/AN3/VREF+
Function
TRIS
Setting
I/O
I/O
Type
RA0
0
O
DIG
1
I
TTL
PORTA<0> data input; disabled when analog input enabled.
AN0
1
I
ANA
A/D input channel 0 and comparator C1- input. Default input
configuration on POR; does not affect digital output.
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
A/D input channel 1 and comparator C2- input. Default input
configuration on POR; does not affect digital output.
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
A/D input channel 2 and comparator C2+ input. Default input
configuration on POR; not affected by analog output.
VREF-
1
I
ANA
A/D 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.
1
I
ANA
A/D input channel 3 and comparator C1+ input. Default input
configuration on POR.
AN3
RA4/T0CKI/C1OUT
RA5/AN4/SS/
HLVDIN/C2OUT
OSC2/CLKO/RA6
OSC1/CLKI/RA7
Legend:
Description
LATA<0> data output; not affected by analog input.
VREF+
1
I
ANA
A/D 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.
T0CKI
1
I
ST
Timer0 clock input.
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 MSSP module.
HLVDIN
1
I
ANA
High/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).
CLKO
x
O
DIG
System cycle clock output (FOSC/4) in RC, INTIO1 and EC Oscillator
modes.
RA7
0
O
DIG
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.
CLKI
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).
DS39631E-page 106
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 10-2:
Name
PORTA
SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RA7(1)
RA6(1)
RA5
RA4
RA3
RA2
RA1
RA0
LATA
LATA7(1)
LATA6(1) PORTA Data Latch Register (Read and Write to Data Latch)
TRISA
TRISA7(1) TRISA6(1) PORTA Data Direction Register
Reset
Values
on page
52
52
52
ADCON1
—
—
VCFG1
VCFG0
PCFG3
PCFG2
PCFG1
PCFG0
51
CMCON
C2OUT
C1OUT
C2INV
C1INV
CIS
CM2
CM1
CM0
51
CVRCON
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
51
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’.
© 2008 Microchip Technology Inc.
DS39631E-page 107
PIC18F2420/2520/4420/4520
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., put the corresponding output driver in
a high-impedance mode). Clearing a TRISB bit (= 0)
will make the corresponding PORTB pin an output (i.e.,
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
MOVLW
MOVWF
MOVLW
MOVWF
PORTB
;
;
;
LATB
;
;
;
0Fh
;
ADCON1 ;
;
;
0CFh
;
;
;
TRISB
;
;
;
INITIALIZING PORTB
Initialize PORTB by
clearing output
data latches
Alternate method
to clear output
data latches
Set RB<4:0> as
digital I/O pins
(required if config bit
PBADEN is set)
Value used to
initialize data
direction
Set RB<3:0> as inputs
RB<5:4> as outputs
RB<7:6> as inputs
Four of the PORTB pins (RB<7:4>) have an interrupton-change feature. 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 interrupton-change comparison). The input pins (of RB<7:4>)
are compared with the old value latched on the last
read of PORTB. The “mismatch” outputs of RB<7:4>
are ORed together to generate the RB Port Change
Interrupt with Flag bit, RBIF (INTCON<0>).
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 (except with the
MOVFF (ANY), PORTB instruction).
Clear flag bit, RBIF.
A mismatch condition will continue to set flag bit, RBIF.
Reading PORTB will end the mismatch condition and
allow flag bit, RBIF, to be cleared.
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.
RB3 can be configured by the Configuration bit,
CCP2MX, as the alternate peripheral pin for the CCP2
module (CCP2MX = 0).
Each of the PORTB pins has a weak internal pull-up. A
single control bit can turn on all the pull-ups. This is
performed by clearing bit, RBPU (INTCON2<7>). 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:
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.
By programming the Configuration bit,
PBADEN, RB<4:0> will alternatively be
configured as digital inputs on POR.
DS39631E-page 108
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 10-3:
Pin
RB0/INT0/FLT0/
AN12
RB1/INT1/AN10
RB2/INT2/AN8
RB3/AN9/CCP2
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; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.(1)
External interrupt 0 input.
INT0
1
I
ST
FLT0
1
I
ST
AN12
1
I
ANA
A/D input channel 12.(1)
RB1
0
O
DIG
LATB<1> data output; not affected by analog input.
1
I
TTL
PORTB<1> data input; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.(1)
INT1
1
I
ST
1
I
ANA
A/D input channel 10.(1)
RB2
0
O
DIG
LATB<2> data output; not affected by analog input.
1
I
TTL
PORTB<2> data input; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.(1)
RB6/KBI2/PGC
RB7/KBI3/PGD
Legend:
Note 1:
2:
3:
External Interrupt 1 input.
INT2
1
I
ST
AN8
1
I
ANA
A/D input channel 8.(1)
RB3
0
O
DIG
LATB<3> data output; not affected by analog input.
1
I
TTL
PORTB<3> data input; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.(1)
1
I
ANA
A/D input channel 9.(1)
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; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.(1)
KBI0
1
I
TTL
Interrupt-on-pin change.
AN11
1
I
ANA
A/D input channel 11.(1)
RB5
0
O
DIG
LATB<5> data output.
1
I
TTL
PORTB<5> data input; weak pull-up when RBPU bit is cleared.
CCP2
RB5/KBI1/PGM
Enhanced PWM Fault input (ECCP1 module); enabled in software.
AN10
AN9
RB4/KBI0/AN11
Description
(2)
RB4
External interrupt 2 input.
KBI1
1
I
TTL
Interrupt-on-pin change.
PGM
x
I
ST
Single-Supply In-Circuit Serial Programming™ mode entry (ICSP™).
Enabled by LVP Configuration bit; all other pin functions disabled.
RB6
0
O
DIG
LATB<6> data output.
1
I
TTL
PORTB<6> data input; weak pull-up when RBPU bit is cleared.
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; weak pull-up when RBPU bit is cleared.
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)
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.
© 2008 Microchip Technology Inc.
DS39631E-page 109
PIC18F2420/2520/4420/4520
TABLE 10-4:
Name
PORTB
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 Register
INTCON
GIE/GIEH PEIE/GIEL
TMR0IE
Reset
Values
on page
52
52
52
INT0IE
INTEDG0 INTEDG1 INTEDG2
RBIE
TMR0IF
INT0IF
RBIF
49
INTCON2
RBPU
—
TMR0IP
—
RBIP
49
INTCON3
INT2IP
INT1IP
—
INT2IE
INT1IE
—
INT2IF
INT1IF
49
ADCON1
—
—
VCFG1
VCFG0
PCFG3
PCFG2
PCFG1
PCFG0
51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTB.
DS39631E-page 110
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
10.3
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., put the corresponding output driver in
a high-impedance mode). Clearing a TRISC bit (= 0)
will make the corresponding PORTC pin an output (i.e.,
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.
PORTC is multiplexed with several peripheral functions
(Table 10-5). The pins have Schmitt Trigger input buffers. RC1 is normally configured by Configuration bit,
CCP2MX, as the default peripheral pin of the CCP2
module (default/erased state, CCP2MX = 1).
When enabling peripheral functions, care should be
taken in defining TRIS bits for each PORTC pin. Some
peripherals override the TRIS bit to make a pin an output,
while other peripherals override the TRIS bit to make a
pin an input. The user should refer to the corresponding
peripheral section for additional information.
© 2008 Microchip Technology Inc.
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.
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
DS39631E-page 111
PIC18F2420/2520/4420/4520
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(2)
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:
2:
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.
1
I
I2C/SMB
0
O
DIG
I2C clock input (MSSP module); input type depends on module setting.
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 (EUSART module);
takes priority over port data. User must configure as output.
CK
1
O
DIG
Synchronous serial clock output (EUSART module); takes priority
over port data.
1
I
ST
Synchronous serial clock input (EUSART module).
0
O
DIG
LATC<7> data output.
1
I
ST
PORTC<7> data input.
RX
1
I
ST
Asynchronous serial receive data input (EUSART module).
DT
1
O
DIG
Synchronous serial data output (EUSART module); takes priority over
port data.
1
I
ST
Synchronous serial data input (EUSART 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.
Enhanced PWM output is available only on PIC18F4520 devices.
DS39631E-page 112
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
Reset
Values
on page
52
LATC
PORTC Data Latch Register (Read and Write to Data Latch)
52
TRISC
PORTC Data Direction Register
52
© 2008 Microchip Technology Inc.
DS39631E-page 113
PIC18F2420/2520/4420/4520
10.4
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., put the corresponding output driver in
a high-impedance mode). Clearing a TRISD bit (= 0)
will make the corresponding PORTD pin an output (i.e.,
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 10.6 “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.
DS39631E-page 114
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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).
© 2008 Microchip Technology Inc.
DS39631E-page 115
PIC18F2420/2520/4420/4520
TABLE 10-8:
Name
PORTD
LATD
TRISD
(1)
TRISE
CCP1CON
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
Reset
Values
on page
52
PORTD Data Latch Register (Read and Write to Data Latch)
52
PORTD Data Direction Register
52
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
52
P1M1(1)
P1M0(1)
DC1B1
DC1B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0
51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTD.
Note 1: These registers and/or bits are unimplemented on 28-oin devices.
DS39631E-page 116
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
10.5
PORTE, TRISE and LATE
Registers
Depending on the particular PIC18F2420/2520/4420/
4520 device selected, PORTE is implemented in two
different ways.
For 40/44-pin 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., put the corresponding output
driver in a high-impedance mode). Clearing a TRISE bit
(= 0) will make the corresponding PORTE pin an output
(i.e., 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.
© 2008 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
MOVWF
MOVLW
MOVWF
10.5.1
PORTE
;
;
;
LATE
;
;
;
0Ah
;
ADCON1 ;
03h
;
;
;
TRISE
;
;
;
INITIALIZING PORTE
Initialize PORTE by
clearing output
data latches
Alternate method
to clear output
data latches
Configure A/D
for digital inputs
Value used to
initialize data
direction
Set RE<0> as inputs
RE<1> as outputs
RE<2> as inputs
PORTE IN 28-PIN DEVICES
For 28-pin devices, PORTE is only available when
Master Clear functionality is disabled (MCLRE = 0). In
these cases, PORTE is a single bit, input only port comprised of RE3 only. The pin operates as previously
described.
DS39631E-page 117
PIC18F2420/2520/4420/4520
REGISTER 10-1:
R-0
TRISE REGISTER (40/44-PIN DEVICES ONLY)
R-0
IBF
OBF
R/W-0
IBOV
R/W-0
U-0
R/W-1
R/W-1
R/W-1
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 in 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
DS39631E-page 118
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 10-9:
PORTE I/O SUMMARY
Pin
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)
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 28-pin and 40/44-pin devices. All other PORTE pins are only implemented on 40/44-pin
devices.
RE3 does not have a corresponding TRIS bit to control data direction.
TABLE 10-10: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE
Name
Bit 2
Bit 1
Bit 0
RE2
RE1
RE0
Reset
Values
on page
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
PORTE
—
—
—
—
RE3(1,2)
LATE(2)
—
—
—
—
—
TRISE
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
52
ADCON1
—
—
VCFG1
VCFG0
PCFG3
PCFG2
PCFG1
PCFG0
51
LATE Data Latch Register
52
52
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 28-pin and 40/44-pin devices. All other bits are
implemented only when PORTE is implemented (i.e., 40/44-pin devices).
© 2008 Microchip Technology Inc.
DS39631E-page 119
PIC18F2420/2520/4420/4520
10.6
Note:
Parallel Slave Port
The Parallel Slave Port is only available on
40/44-pin 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). The A/D port configuration bits,
PFCG<3:0> (ADCON1<3:0>), must also be set to a
value in the range of ‘1010’ through ‘1111’.
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
WR LATD
or
WR PORTD
Q
RDx pin
CK
Data Latch
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.
DS39631E-page 120
D
Q
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.
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
Note:
TTL
WR
I/O pins have diode protection to VDD and VSS.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
TABLE 10-11: REGISTERS ASSOCIATED WITH PARALLEL SLAVE PORT
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
PORTD
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
52
LATD
PORTD Data Latch Register (Read and Write to Data Latch)
52
TRISD
PORTD Data Direction Register
52
PORTE
—
—
—
—
RE3
LATE
—
—
—
—
—
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
52
TMR0IF
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
TRISE
INTCON
GIE/GIEH PEIE/GIEL
RE2
RE1
RE0
LATE Data Latch Register
52
52
PIR1
PSPIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
—
—
VCFG1
VCFG0
PCFG3
PCFG2
PCFG1
PCFG0
51
ADCON1
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Parallel Slave Port.
© 2008 Microchip Technology Inc.
DS39631E-page 121
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 122
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
11.0
TIMER0 MODULE
The Timer0 module incorporates the following features:
• 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 11-1:
The T0CON register (Register 11-1) controls all
aspects of the module’s operation, including the
prescale selection. It is both readable and writable.
A simplified block diagram of the Timer0 module in 8-bit
mode is shown in Figure 11-1. Figure 11-2 shows a
simplified block diagram of the Timer0 module in 16-bit
mode.
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 (CLKO)
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
© 2008 Microchip Technology Inc.
DS39631E-page 123
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11.1
Timer0 Operation
Timer0 can operate as either a timer or a counter; the
mode is selected with the T0CS bit (T0CON<5>). In
Timer mode (T0CS = 0), the module increments on
every clock by default unless a different prescaler value
is selected (see Section 11.3 “Prescaler”). If the
TMR0 register is written to, the increment is inhibited
for the following two instruction cycles. The user can
work around this by writing an adjusted value to the
TMR0 register.
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 (T0CON<4>); clearing this bit selects
the rising edge. Restrictions on the external clock input
are discussed below.
An external clock source can be used to drive Timer0;
however, it must meet certain requirements to ensure
that the external clock can be synchronized with the
FIGURE 11-1:
internal phase clock (TOSC). There is a delay between
synchronization and the onset of incrementing the
timer/counter.
11.2
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 not directly readable nor writable (refer to Figure 11-2). 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 having to verify that the read of the high
and low byte were valid, 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. The high
byte 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.
TIMER0 BLOCK DIAGRAM (8-BIT MODE)
FOSC/4
0
0
1
Programmable
Prescaler
T0CKI pin
T0SE
T0CS
1
Sync with
Internal
Clocks
(2 TCY Delay)
8
3
T0PS<2:0>
8
PSA
Note:
Set
TMR0IF
on Overflow
TMR0L
Internal Data Bus
Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
FIGURE 11-2:
FOSC/4
TIMER0 BLOCK DIAGRAM (16-BIT MODE)
0
0
1
T0CKI pin
T0SE
T0CS
Programmable
Prescaler
1
Sync with
Internal
Clocks
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:
Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
DS39631E-page 124
© 2008 Microchip Technology Inc.
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11.3
11.3.1
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
(T0CON<3:0>) which determine the prescaler
assignment and prescale ratio.
Clearing the PSA bit assigns the prescaler to the
Timer0 module. When it is assigned, prescale values
from 1:2 through 1:256 in 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 11-1:
Name
SWITCHING PRESCALER
ASSIGNMENT
The prescaler assignment is fully under software
control and can be changed “on-the-fly” during program
execution.
11.4
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 (INTCON<5>). Before reenabling the interrupt, the TMR0IF bit must be cleared
in software by 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
50
50
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
50
RA5
RA4
RA3
RA2
RA1
RA0
52
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’.
© 2008 Microchip Technology Inc.
DS39631E-page 125
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NOTES:
DS39631E-page 126
© 2008 Microchip Technology Inc.
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12.0
TIMER1 MODULE
The Timer1 timer/counter module incorporates these
features:
• Software selectable operation as a 16-bit timer or
counter
• Readable and writable 8-bit registers (TMR1H
and TMR1L)
• Selectable clock source (internal or external) with
device clock or Timer1 oscillator internal options
• Interrupt-on-overflow
• Reset on CCP Special Event Trigger
• Device clock status flag (T1RUN)
REGISTER 12-1:
A simplified block diagram of the Timer1 module is
shown in Figure 12-1. A block diagram of the module’s
operation in Read/Write mode is shown in Figure 12-2.
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 12-1). It also contains the Timer1
Oscillator Enable bit (T1OSCEN). Timer1 can be
enabled or disabled by setting or clearing control bit,
TMR1ON (T1CON<0>).
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 = Device clock is derived from Timer1 oscillator
0 = Device 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
© 2008 Microchip Technology Inc.
DS39631E-page 127
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12.1
cycle (FOSC/4). When the bit is set, Timer1 increments
on every rising edge of the Timer1 external clock input
or the Timer1 oscillator, if enabled.
Timer1 Operation
Timer1 can operate in one of these modes:
• Timer
• Synchronous Counter
• Asynchronous Counter
When Timer1 is enabled, the RC1/T1OSI and RC0/
T1OSO/T13CKI pins become inputs. 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 (T1CON<1>). When TMR1CS is cleared
(= 0), Timer1 increments on every internal instruction
FIGURE 12-1:
TIMER1 BLOCK DIAGRAM
Timer1 Oscillator
Timer1 Clock Input
On/Off
T1OSO/T13CKI
1
1
FOSC/4
Internal
Clock
T1OSI
Synchronize
Prescaler
1, 2, 4, 8
0
Detect
0
2
T1OSCEN(1)
Sleep Input
TMR1CS
Timer1
On/Off
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 12-2:
TIMER1 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Clock Input
Timer1 Oscillator
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
TMR1CS
Clear TMR1
(CCP Special Event Trigger)
Timer1
On/Off
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.
DS39631E-page 128
© 2008 Microchip Technology Inc.
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12.2
Timer1 16-Bit Read/Write Mode
Timer1 can be configured for 16-bit reads and writes
(see Figure 12-2). When the RD16 control bit
(T1CON<7>) 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 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.
TABLE 12-1:
Osc Type
LP
CAPACITOR SELECTION FOR
THE TIMER OSCILLATOR
Freq
32 kHz
C1
27 pF
C2
(1)
27 pF(1)
Note 1: Microchip suggests these values 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.
A write to the high byte of Timer1 must also take place
through the TMR1H Buffer register. The Timer1 high
byte is updated with the contents of TMR1H when a
write occurs to TMR1L. This allows a user to write all
16 bits to both the high and low bytes of Timer1 at once.
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate
values
of
external
components.
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.
4: Capacitor values are for design guidance
only.
12.3
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 (T1CON<3>). The oscillator is a lowpower 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 12-3. Table 12-1
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 12-3:
EXTERNAL COMPONENTS
FOR THE TIMER1 LP
OSCILLATOR
C1
27 pF
PIC18FXXXX
T1OSI
XTAL
32.768 kHz
T1OSO
C2
27 pF
Note:
See the Notes with Table 12-1 for additional
information about capacitor selection.
12.3.1
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> (OSCCON<1:0>), to ‘01’, the device
switches to SEC_RUN mode; both the CPU and
peripherals are clocked from the Timer1 oscillator. If the
IDLEN bit (OSCCON<7>) 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
(T1CON<6>), is set. This can be used to determine the
controller’s current clocking mode. It can also indicate
the clock source being currently 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.
12.3.2
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 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.
© 2008 Microchip Technology Inc.
DS39631E-page 129
PIC18F2420/2520/4420/4520
12.3.3
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 12-3, 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 12-4, may be helpful when used on a
single-sided PCB or in addition to a ground plane.
FIGURE 12-4:
OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
12.5
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 15.3.4 “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 CCPRxH:CCPRxL 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:
VDD
VSS
OSC1
OSC2
RC0
RC1
RC2
Note: Not drawn to scale.
12.4
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 interrupt flag bit, TMR1IF
(PIR1<0>). This interrupt can be enabled or disabled
by setting or clearing the Timer1 Interrupt Enable bit,
TMR1IE (PIE1<0>).
Resetting Timer1 Using the CCP
Special Event Trigger
12.6
The Special Event Triggers from the CCP2
module will not set the TMR1IF interrupt
flag bit (PIR1<0>).
Using Timer1 as a Real-Time Clock
Adding an external LP oscillator to Timer1 (such as the
one described in Section 12.3 “Timer1 Oscillator”)
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 12-1, 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 as the previous counter overflow.
Since the register pair is 16 bits wide, counting up to
overflow the register directly from a 32.768 kHz clock
would take 2 seconds. 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.
DS39631E-page 130
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
12.7
Considerations in Asynchronous
Counter Mode
Following a Timer1 interrupt and an update to the
TMR1 registers, the Timer1 module uses a falling edge
on its clock source to trigger the next register update on
the rising edge. If the update is completed after the
clock input has fallen, the next rising edge will not be
counted.
If the application can reliably update TMR1 before the
timer input goes low, no additional action is needed.
Otherwise, an adjusted update can be performed
following a later Timer1 increment. This can be done by
EXAMPLE 12-1:
monitoring TMR1L within the interrupt routine until it
increments, and then updating the TMR1H:TMR1L
register pair while the clock is low, or one-half of the
period of the clock source. Assuming that Timer1 is
being used as a Real-Time Clock, the clock source is a
32.768 kHz crystal oscillator; in this case, one half
period of the clock is 15.25 μs.
The Real-Time Clock application code in Example 12-1
shows a typical ISR for Timer1, as well as the optional
code required if the update cannot be done reliably
within the required interval.
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
RTCisr
BTFSC
BRA
BTFSS
BRA
TMR1L,0
$-2
TMR1L,0
$-2
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
secs
mins, F
.59
mins
mins
hours, F
.23
hours
hours
© 2008 Microchip Technology Inc.
; Preload TMR1 register pair
; for 1 second overflow
; Configure for external clock,
; Asynchronous operation, external oscillator
; Initialize timekeeping registers
;
; Enable Timer1 interrupt
;
;
;
;
;
;
;
Start ISR here
Insert the next 4 lines of code when TMR1
can not be reliably updated before clock pulse goes low
wait for TMR1L<0> to become clear
(may already be clear)
wait for TMR1L<0> to become set
TMR1 has just incremented
;
;
;
;
;
If TMR1 update can be completed before clock pulse goes low
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
DS39631E-page 131
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TABLE 12-2:
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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
IPR1
PSPIE
PSPIP
TMR1L
Timer1 Register Low Byte
50
TMR1H
Timer1 Register High Byte
50
T1CON
RD16
T1RUN
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
TMR1CS
TMR1ON
50
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.
DS39631E-page 132
© 2008 Microchip Technology Inc.
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13.0
TIMER2 MODULE
13.1
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 13-1), which enables or disables the timer
and configures the prescaler and postscaler. Timer2
can be shut off by clearing control bit, TMR2ON
(T2CON<2>), to minimize power consumption.
A simplified block diagram of the module is shown in
Figure 13-1.
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-by16 prescale options; these are selected by the prescaler
control bits, T2CKPS<1:0> (T2CON<1:0>). 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 13.2 “Timer2 Interrupt”).
The TMR2 and PR2 registers are both directly readable
and writable. The TMR2 register is cleared on any
device Reset, while the PR2 register initializes at 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 13-1:
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
© 2008 Microchip Technology Inc.
x = Bit is unknown
DS39631E-page 133
PIC18F2420/2520/4420/4520
13.2
Timer2 Interrupt
13.3
Timer2 also can 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 (PIR1<1>). The interrupt is
enabled by setting the TMR2 Match Interrupt Enable
bit, TMR2IE (PIE1<1>).
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 optionally be 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> (T2CON<6:3>).
FIGURE 13-1:
TIMER2 BLOCK DIAGRAM
4
T2OUTPS<3:0>
1:1 to 1:16
Postscaler
Set TMR2IF
2
T2CKPS<1:0>
TMR2/PR2
Match
Reset
1:1, 1:4, 1:16
Prescaler
FOSC/4
TMR2
TMR2 Output
(to PWM or MSSP)
Comparator
8
PR2
8
8
Internal Data Bus
TABLE 13-1:
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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
TMR2
T2CON
PR2
Timer2 Register
—
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON
50
T2CKPS1 T2CKPS0
Timer2 Period Register
50
50
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.
DS39631E-page 134
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
14.0
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 14-1:
A simplified block diagram of the Timer3 module is
shown in Figure 14-1. A block diagram of the module’s
operation in Read/Write mode is shown in Figure 14-2.
The Timer3 module is controlled through the T3CON
register (Register 14-1). It also selects the clock source
options for the CCP modules (see Section 15.1.1
“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 the CCP modules
01 = Timer3 is the capture/compare clock source for CCP2;
Timer1 is the capture/compare clock source for CCP1
00 = Timer1 is the capture/compare clock source for the CCP modules
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
© 2008 Microchip Technology Inc.
DS39631E-page 135
PIC18F2420/2520/4420/4520
14.1
The operating mode is determined by the clock select
bit, TMR3CS (T3CON<1>). 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 Operation
Timer3 can operate in one of three modes:
• Timer
• Synchronous Counter
• Asynchronous Counter
FIGURE 14-1:
As with Timer1, the RC1/T1OSI and RC0/T1OSO/
T13CKI pins become inputs when the Timer1 oscillator
is enabled. This means the values of TRISC<1:0> are
ignored and the pins are read as ‘0’.
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
Timer3
On/Off
T3CKPS<1:0>
T3SYNC
TMR3ON
CCP1/CCP2 Special Event Trigger
CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
Set
TMR3IF
on Overflow
TMR3
High Byte
TMR3L
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
FIGURE 14-2:
TIMER3 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Clock Input
Timer1 Oscillator
1
T13CKI/T1OSO
1
FOSC/4
Internal
Clock
T1OSI
Synchronize
Prescaler
1, 2, 4, 8
Detect
0
0
2
T1OSCEN(1)
T3CKPS<1:0>
T3SYNC
TMR3ON
Sleep Input
TMR3CS
CCP1/CCP2 Special Event Trigger
CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
Timer3
On/Off
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.
DS39631E-page 136
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
14.2
Timer3 16-Bit Read/Write Mode
14.4
Timer3 Interrupt
Timer3 can be configured for 16-bit reads and writes
(see Figure 14-2). When the RD16 control bit
(T3CON<7>) 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.
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 (PIR2<1>).
This interrupt can be enabled or disabled by setting or
clearing the Timer3 Interrupt Enable bit, TMR3IE
(PIE2<1>).
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.
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 15.3.4
“Special Event Trigger” for more information).
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.
14.3
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 (T1CON<3>) bit. 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.
14.5
Resetting Timer3 Using the CCP
Special Event Trigger
The module must be configured as either a timer or
synchronous counter to take advantage of this feature.
When used this way, the CCPRxH:CCPRxL 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 (PIR1<0>).
The Timer1 oscillator is described in Section 12.0
“Timer1 Module”.
TABLE 14-1:
Name
INTCON
REGISTERS ASSOCIATED WITH TIMER3 AS A TIMER/COUNTER
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
49
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
IPR2
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
TMR3L
Timer3 Register Low Byte
51
TMR3H
Timer3 Register High Byte
51
T1CON
RD16
T1RUN
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
TMR1CS
TMR1ON
50
T3CON
RD16
T3CCP2
T3CKPS1 T3CKPS0
TMR3CS
TMR3ON
51
T3CCP1
T3SYNC
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer3 module.
© 2008 Microchip Technology Inc.
DS39631E-page 137
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 138
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
15.0
CAPTURE/COMPARE/PWM
(CCP) MODULES
PIC18F2420/2520/4420/4520 devices all 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.
In 28-pin devices, the two standard CCP modules (CCP1
and CCP2) operate as described in this chapter. In 40/
44-pin devices, 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”.
REGISTER 15-1:
The capture and compare operations described in this
chapter apply to all standard and Enhanced CCP
modules.
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.
CCPxCON: CCPx CONTROL REGISTER (28-PIN DEVICES)
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
DCxB1
DCxB0
CCPxM3
CCPxM2
CCPxM1
CCPxM0
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
DCxB<1:0>: PWM Duty Cycle bit 1 and bit 0 for CCPx 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 (DCxB<9:2>)
of the duty cycle are found in CCPRxL.
bit 3-0
CCPxM<3:0>: CCPx Module Mode Select bits
0000 = Capture/Compare/PWM disabled (resets CCPx module)
0001 = Reserved
0010 = Compare mode, toggle output on match (CCPxIF 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 CCPx pin low; on compare match, force CCPx pin high (CCPxIF bit is set)
1001 = Compare mode, initialize CCPx pin high; on compare match, force CCPx pin low (CCPxIF bit is set)
1010 = Compare mode, generate software interrupt on compare match (CCPxIF bit is set, CCPx pin
reflects I/O state)
1011 = Compare mode, trigger special event; reset timer; CCP2 match starts A/D conversion (CCPxIF
bit is set)
11xx = PWM mode
© 2008 Microchip Technology Inc.
DS39631E-page 139
PIC18F2420/2520/4420/4520
15.1
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.
15.1.1
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 15-1:
CCP MODE – TIMER
RESOURCE
CCP/ECCP Mode
Timer Resource
Capture
Compare
PWM
Timer1 or Timer3
Timer1 or Timer3
Timer2
TABLE 15-2:
The assignment of a particular timer to a module is
determined by the Timer to CCP enable bits in the
T3CON register (Register 14-1). Both modules may be
active at any given time and may share the same timer
resource if they are configured to operate in the same
mode (Capture/Compare or PWM) at the same time. The
interactions between the two modules are summarized in
Figure 15-1 and Figure 15-2. In Timer1 in Asynchronous
Counter mode, the capture operation will not work.
15.1.2
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
which pin CCP2 is multiplexed to. 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(1)
None
Compare
PWM(1)
None
PWM(1)
Capture
None
(1)
PWM
PWM(1)
Note 1:
Compare
PWM(1)
None
Both PWMs will have the same frequency and update rate (TMR2 interrupt).
Includes standard and Enhanced PWM operation.
DS39631E-page 140
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
15.2
15.2.3
Capture Mode
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.
In Capture mode, the CCPRxH:CCPRxL register pair
captures the 16-bit value of the TMR1 or TMR3 register
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
15.2.4
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 15-1 shows the
recommended method for switching between capture
prescalers. This example also clears the prescaler
counter and will not generate the “false” interrupt.
CCP PIN CONFIGURATION
In Capture mode, the appropriate CCPx pin should be
configured as an input by setting the corresponding
TRIS direction bit.
Note:
15.2.2
If RB3/CCP2 or RC1/CCP2 is configured
as an output, a write to the port can cause
a capture condition.
EXAMPLE 15-1:
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 will not work. The timer to be
used with each CCP module is selected in the T3CON
register (see Section 15.1.1 “CCP Modules and Timer
Resources”).
FIGURE 15-1:
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.
The event is selected by the mode select bits,
CCPxM<3:0> (CCPxCON<3:0>). When a capture is
made, the interrupt request flag bit, CCPxIF, is set; it
must be cleared in software. If another capture occurs
before the value in register CCPRx is read, the old
captured value is overwritten by the new captured value.
15.2.1
SOFTWARE INTERRUPT
CHANGING BETWEEN
CAPTURE PRESCALERS
(CCP2 SHOWN)
CLRF
MOVLW
CCP2CON
NEW_CAPT_PS
MOVWF
CCP2CON
;
;
;
;
;
;
Turn CCP module off
Load WREG with the
new prescaler mode
value and CCP ON
Load CCP2CON with
this value
CAPTURE MODE OPERATION BLOCK DIAGRAM
TMR3H
Set CCP1IF
T3CCP2
CCP1 pin
Prescaler
÷ 1, 4, 16
and
Edge Detect
CCP1CON<3:0>
Q1:Q4
CCP2CON<3:0>
4
4
CCPR1L
TMR1
Enable
TMR1H
TMR1L
TMR3H
TMR3L
Set CCP2IF
4
T3CCP1
T3CCP2
CCP2 pin
Prescaler
÷ 1, 4, 16
TMR3
Enable
CCPR1H
T3CCP2
TMR3L
and
Edge Detect
TMR3
Enable
CCPR2H
CCPR2L
TMR1
Enable
T3CCP2
T3CCP1
© 2008 Microchip Technology Inc.
TMR1H
TMR1L
DS39631E-page 141
PIC18F2420/2520/4420/4520
15.3
15.3.2
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 may not work.
•
•
•
•
15.3.3
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. A CCP interrupt is generated when the
CCPxIF interrupt flag is set while the CCPxIE bit is set.
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.
15.3.1
15.3.4
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
Clearing the CCP2CON register will force
the RB3 or RC1 compare output latch
(depending on device configuration) to the
default low level. This is not the PORTB or
PORTC I/O data latch.
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.
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 15-2:
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
T3CCP1
Special Event Trigger
(Timer1/Timer3 Reset, A/D Trigger)
T3CCP2
Set CCP2IF
Comparator
CCPR2H
CCPR2L
Compare
Match
CCP2 pin
Output
Logic
4
S
Q
R
TRIS
Output Enable
CCP2CON<3:0>
DS39631E-page 142
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 15-3:
Name
INTCON
REGISTERS ASSOCIATED WITH CAPTURE, COMPARE, TIMER1 AND TIMER3
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
49
IPEN
SBOREN
—
RI
TO
PD
POR
BOR
48
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
(1)
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
RCON
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
IPR2
TRISB
PORTB Data Direction Register
TRISC
PORTC Data Direction Register
52
TMR1L
Timer1 Register Low Byte
50
TMR1H
Timer1 Register High Byte
T1CON
RD16
T1RUN
Timer3 Register High Byte
TMR3L
Timer3 Register Low Byte
RD16
T3CCP2
50
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
TMR3H
T3CON
52
TMR1CS TMR1ON
50
51
51
T3CKPS1 T3CKPS0
T3CCP1
T3SYNC
TMR3CS TMR3ON
51
CCPR1L
Capture/Compare/PWM Register 1 Low Byte
51
CCPR1H
Capture/Compare/PWM Register 1 High Byte
51
CCP1CON
P1M1(1)
P1M0(1)
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
51
51
51
CCP2M3
CCP2M2
CCP2M1
CCP2M0
51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by Capture/Compare, Timer1 or Timer3.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
© 2008 Microchip Technology Inc.
DS39631E-page 143
PIC18F2420/2520/4420/4520
15.4
15.4.1
PWM Mode
In Pulse-Width Modulation (PWM) mode, the CCPx pin
produces up to a 10-bit resolution PWM output. Since
the CCP2 pin is multiplexed with a PORTB or PORTC
data latch, the appropriate TRIS bit must be cleared to
make the CCP2 pin an output.
Clearing the CCP2CON register will force
the RB3 or RC1 output latch (depending on
device configuration) to the default low
level. This is not the PORTB or PORTC I/O
data latch.
Note:
Figure 15-3 shows a simplified block diagram of the
CCP module in PWM mode.
For a step-by-step procedure on how to set up the CCP
module for PWM operation, see Section 15.4.4
“Setup for PWM Operation”.
FIGURE 15-3:
SIMPLIFIED PWM BLOCK
DIAGRAM
The PWM period is specified by writing to the PR2
register. The PWM period can be calculated using the
following formula:
EQUATION 15-1:
PWM Period = [(PR2) + 1] • 4 • TOSC •
(TMR2 Prescale Value)
PWM frequency is defined as 1/[PWM period].
When TMR2 is equal to PR2, the following three events
occur on the next increment cycle:
• TMR2 is cleared
• The CCPx pin is set (exception: if PWM duty
cycle = 0%, the CCPx pin will not be set)
• The PWM duty cycle is latched from CCPRxL into
CCPRxH
Note:
CCPxCON<5:4>
Duty Cycle Registers
CCPRxL
15.4.2
CCPRxH (Slave)
CCPx Output
R
Comparator
TMR2
(Note 1)
Comparator
S
Clear Timer,
CCPx pin and
latch D.C.
PR2
Q
Corresponding
TRIS bit
Note 1: The 8-bit TMR2 value is concatenated with the 2-bit
internal Q clock, or 2 bits of the prescaler, to create the
10-bit time base.
A PWM output (Figure 15-4) has a time base (period)
and a time that the output stays high (duty cycle). The
frequency of the PWM is the inverse of the period
(1/period).
FIGURE 15-4:
PWM PERIOD
The Timer2 postscalers (see Section 13.0
“Timer2 Module”) are not used in the
determination of the PWM frequency. The
postscaler could be used to have a servo
update rate at a different frequency than
the PWM output.
PWM DUTY CYCLE
The PWM duty cycle is specified by writing to the
CCPRxL register and to the CCPxCON<5:4> bits. Up
to 10-bit resolution is available. The CCPRxL contains
the eight MSbs and the CCPxCON<5:4> bits contain
the two LSbs. This 10-bit value is represented by
CCPRxL:CCPxCON<5:4>. The following equation is
used to calculate the PWM duty cycle in time:
EQUATION 15-2:
PWM Duty Cycle = (CCPRXL:CCPXCON<5:4>) •
TOSC • (TMR2 Prescale Value)
CCPRxL and CCPxCON<5:4> can be written to at any
time, but the duty cycle value is not latched into
CCPRxH until after a match between PR2 and TMR2
occurs (i.e., the period is complete). In PWM mode,
CCPRxH is a read-only register.
PWM OUTPUT
Period
Duty Cycle
TMR2 = PR2
TMR2 = Duty Cycle
TMR2 = PR2
DS39631E-page 144
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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.
EQUATION 15-3:
F OSC
log ⎛ ---------------⎞
⎝ F PWM⎠
PWM Resolution (max) = -----------------------------bits
log ( 2 )
When the CCPRxH and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or 2 bits of
the TMR2 prescaler, the CCPx pin is cleared.
Note:
The maximum PWM resolution (bits) for a given PWM
frequency is given by the equation:
TABLE 15-4:
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
PWM Frequency
Timer Prescaler (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
15.4.3
If the PWM duty cycle value is longer than
the PWM period, the CCPx pin will not be
cleared.
2.44 kHz
9.77 kHz
39.06 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
PWM AUTO-SHUTDOWN
(CCP1 ONLY)
The PWM auto-shutdown features of the Enhanced CCP
module are also available to CCP1 in 28-pin devices. The
operation of this feature is discussed in detail in
Section 16.4.7 “Enhanced PWM Auto-Shutdown”.
Auto-shutdown features are not available for CCP2.
15.4.4
SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the CCP module for PWM operation:
1.
2.
3.
4.
5.
© 2008 Microchip Technology Inc.
156.25 kHz
Set the PWM period by writing to the PR2
register.
Set the PWM duty cycle by writing to the
CCPRxL register and CCPxCON<5:4> bits.
Make the CCPx pin an output by clearing the
appropriate TRIS bit.
Set the TMR2 prescale value, then enable
Timer2 by writing to T2CON.
Configure the CCPx module for PWM operation.
DS39631E-page 145
PIC18F2420/2520/4420/4520
TABLE 15-5:
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
49
IPEN
SBOREN
—
RI
TO
PD
POR
BOR
48
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE
(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
RCON
TRISB
PORTB Data Direction Register
52
TRISC
PORTC Data Direction Register
52
TMR2
Timer2 Register
50
PR2
Timer2 Period Register
50
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(1)
P1M0(1)
DC1B1
DC1B0
50
51
51
CCP1M3
CCP1M2
CCP1M1
CCP1M0
51
CCPR2L
Capture/Compare/PWM Register 2 Low Byte
51
CCPR2H
Capture/Compare/PWM Register 2 High Byte
51
CCP2CON
ECCP1AS
PWM1CON
—
—
ECCPASE ECCPAS2
PRSEN
PDC6(1)
DC2B1
DC2B0
CCP2M3
CCP2M2
ECCPAS1
ECCPAS0
PSSAC1
PSSAC0 PSSBD1(1) PSSBD0(1)
CCP2M1
51
PDC5(1)
PDC4(1)
PDC3(1)
PDC2(1)
51
PDC1(1)
CCP2M0
PDC0(1)
51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PWM or Timer2.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
DS39631E-page 146
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
16.0
ENHANCED CAPTURE/
COMPARE/PWM (ECCP)
MODULE
Note:
The ECCP module is implemented only in
40/44-pin devices.
In PIC18F4420/4520 devices, CCP1 is implemented as
a standard CCP module with Enhanced PWM
capabilities. These include the provision for 2 or 4 output
channels, user-selectable polarity, dead-band control
REGISTER 16-1:
and automatic shutdown and restart. The enhanced
features are discussed in detail in Section 16.4
“Enhanced PWM 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 16-2. It differs from the CCPxCON
registers in PIC18F2420/2520 devices in that the two
Most Significant bits are implemented to control PWM
functionality.
CCP1CON: ECCP CONTROL REGISTER (40/44-PIN DEVICES)
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 CCP1M3:CCP1M2 = 00, 01, 10:
xx = P1A assigned as capture/compare input/output; P1B, P1C, P1D assigned as port pins
If CCP1M3:CCP1M2 = 11:
00 = Single output, P1A modulated; P1B, P1C, P1D assigned as port pins
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 = Capture mode
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 CCP1IF 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
© 2008 Microchip Technology Inc.
DS39631E-page 147
PIC18F2420/2520/4420/4520
In addition to the expanded range of modes available
through the CCP1CON register and ECCP1AS
register, the ECCP module has an additional register
associated with Enhanced PWM operation and
auto-shutdown features. It is:
• PWM1CON (PWM Dead-Band Delay)
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. 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 15.1.1
“CCP
Modules
and
Timer
Resources”.
TABLE 16-1:
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 15.2
“Capture Mode” and Section 15.3 “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 ECCP 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.
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 15.4
“PWM Mode”. This is also sometimes referred to as
“Compatible CCP” mode, as in Table 16-1.
Note:
When setting up single output PWM
operations, users are free to use either of
the processes described in Section 15.4.4
“Setup for PWM Operation” or
Section 16.4.9 “Setup for PWM Operation”. The latter is more generic and will
work for either single or multi-output PWM.
PIN ASSIGNMENTS FOR VARIOUS ECCP MODES
ECCP Mode
CCP1CON
Configuration
RC2
RD5
RD6
RD7
All 40/44-Pin Devices:
Compatible CCP
00xx 11xx
CCP1
RD5/PSP5
RD6/PSP6
RD7/PSP7
Dual PWM
10xx 11xx
P1A
P1B
RD6/PSP6
RD7/PSP7
Quad PWM
x1xx 11xx
P1A
P1B
P1C
P1D
Legend: x = Don’t care. Shaded cells indicate pin assignments not used by ECCP in a given mode.
DS39631E-page 148
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
16.4
16.4.1
Enhanced PWM Mode
The Enhanced PWM mode provides additional PWM
output options for a broader range of control applications. The module is a backward compatible version of
the standard CCP module and offers up to four outputs,
designated P1A through P1D. Users are also able to
select the polarity of the signal (either active-high or
active-low). The module’s output mode and polarity are
configured by setting the P1M<1:0> and CCP1M<3:0>
bits of the CCP1CON register.
Figure 16-1 shows a simplified block diagram of PWM
operation. All control registers are double-buffered and
are loaded at the beginning of a new PWM cycle (the
period boundary when Timer2 resets) in order to prevent glitches on any of the outputs. The exception is the
PWM Dead-Band Delay register, PWM1CON, which is
loaded at either the duty cycle boundary or the period
boundary (whichever comes first). Because of the buffering, the module waits until the assigned timer resets
instead of starting immediately. This means that
Enhanced PWM waveforms do not exactly match the
standard PWM waveforms, but are instead offset by
one full instruction cycle (4 TOSC).
PWM PERIOD
The PWM period is specified by writing to the PR2
register. The PWM period can be calculated using the
following equation.
EQUATION 16-1:
PWM Period =
PWM frequency is defined as 1/[PWM period]. When
TMR2 is equal to PR2, the following three events occur
on the next increment cycle:
• TMR2 is cleared
• The CCP1 pin is set (if PWM duty cycle = 0%, the
CCP1 pin will not be set)
• The PWM duty cycle is copied from CCPR1L into
CCPR1H
Note:
As before, the user must manually configure the
appropriate TRIS bits for output.
FIGURE 16-1:
[(PR2) + 1] • 4 • TOSC •
(TMR2 Prescale Value)
The Timer2 postscaler (see Section 13.0
“Timer2 Module”) is not used in the
determination of the PWM frequency. The
postscaler could be used to have a servo
update rate at a different frequency than
the PWM output.
SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODULE
CCP1CON<5:4>
Duty Cycle Registers
CCP1M<3:0>
4
P1M1<1:0>
2
CCPR1L
CCP1/P1A
CCP1/P1A
TRISx<x>
CCPR1H (Slave)
P1B
R
Comparator
Q
Output
Controller
P1B
TRISx<x>
P1C
TMR2
Comparator
PR2
(Note 1)
P1C
TRISx<x>
S
P1D
Clear Timer,
set CCP1 pin and
latch D.C.
P1D
TRISx<x>
PWM1CON
Note: The 8-bit TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit
time base.
© 2008 Microchip Technology Inc.
DS39631E-page 149
PIC18F2420/2520/4420/4520
16.4.2
PWM DUTY CYCLE
EQUATION 16-3:
The PWM duty cycle is specified by writing to the
CCPR1L register and to the CCP1CON<5:4> bits. Up
to 10-bit resolution is available. The CCPR1L contains
the eight MSbs and the CCP1CON<5:4> bits contain
the two LSbs. This 10-bit value is represented by
CCPR1L:CCP1CON<5:4>. The PWM duty cycle is
calculated by the following equation.
(
log FOSC
FPWM
PWM Resolution (max) =
log(2)
Note:
EQUATION 16-2:
PWM Duty Cycle =
16.4.3
(CCPR1L:CCP1CON<5:4>) •
TOSC • (TMR2 Prescale Value)
CCPR1L and CCP1CON<5:4> can be written to at any
time, but the duty cycle value is not copied into
CCPR1H until a match between PR2 and TMR2 occurs
(i.e., the period is complete). In PWM mode, CCPR1H
is a read-only register.
The CCPR1H 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. When the CCPR1H and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or two bits
of the TMR2 prescaler, the CCP1 pin is cleared. The
maximum PWM resolution (bits) for a given PWM
frequency is given by the following equation.
TABLE 16-2:
) bits
If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
PWM OUTPUT CONFIGURATIONS
The P1M<1:0> bits in the CCP1CON register allow one
of four configurations:
•
•
•
•
Single Output
Half-Bridge Output
Full-Bridge Output, Forward mode
Full-Bridge Output, Reverse mode
The Single Output mode is the standard PWM mode
discussed in Section 16.4 “Enhanced PWM Mode”.
The Half-Bridge and Full-Bridge Output modes are
covered in detail in the sections that follow.
The general relationship of the outputs in all
configurations is summarized in Figure 16-2 and
Figure 16-3.
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
PWM Frequency
Timer Prescaler (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
DS39631E-page 150
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 16-2:
PWM OUTPUT RELATIONSHIPS (ACTIVE-HIGH STATE)
0
CCP1CON<7:6>
00
(Single Output)
Duty
Cycle
SIGNAL
PR2 + 1
Period
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
FIGURE 16-3:
PWM OUTPUT RELATIONSHIPS (ACTIVE-LOW STATE)
CCP1CON<7:6>
00
(Single Output)
SIGNAL
0
Duty
Cycle
PR2 + 1
Period
P1A Modulated
P1A Modulated
10
(Half-Bridge)
Delay(1)
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)
• Duty Cycle = 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 (see Section 16.4.6 “Programmable
Dead-Band Delay”).
© 2008 Microchip Technology Inc.
DS39631E-page 151
PIC18F2420/2520/4420/4520
16.4.4
HALF-BRIDGE MODE
FIGURE 16-4:
In the Half-Bridge Output mode, two pins are used as
outputs to drive push-pull loads. The PWM output signal
is output on the P1A pin, while the complementary PWM
output signal is output on the P1B pin (Figure 16-4). 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 Output mode, the programmable deadband delay can be used to prevent shoot-through
current in half-bridge power devices. The value of bits,
PDC<6:0>, 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” for more details
of the dead-band delay operations.
HALF-BRIDGE PWM
OUTPUT
Period
Period
Duty Cycle
P1A(2)
td
td
P1B(2)
(1)
(1)
(1)
td = Dead-Band Delay
Note 1: At this time, the TMR2 register is equal to the
PR2 register.
2: Output signals are shown as active-high.
Since the P1A and P1B outputs are multiplexed with
the PORTC<2> and PORTD<5> data latches, the
TRISC<2> and TRISD<5> bits must be cleared to
configure P1A and P1B as outputs.
FIGURE 16-5:
EXAMPLES OF HALF-BRIDGE OUTPUT MODE APPLICATIONS
V+
Standard Half-Bridge Circuit (“Push-Pull”)
PIC18F4X2X
FET
Driver
+
V
-
P1A
Load
FET
Driver
+
V
-
P1B
VHalf-Bridge Output Driving a Full-Bridge Circuit
V+
PIC18F4X2X
FET
Driver
FET
Driver
P1A
FET
Driver
Load
FET
Driver
P1B
V-
DS39631E-page 152
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
16.4.5
FULL-BRIDGE MODE
In Full-Bridge Output mode, four pins are used as
outputs; however, only two outputs are active at a time.
In the Forward mode, pin P1A is continuously active
and pin P1D is modulated. In the Reverse mode, pin
P1C is continuously active and pin P1B is modulated.
These are illustrated in Figure 16-6.
FIGURE 16-6:
P1A, P1B, P1C and P1D outputs are multiplexed with
the PORTC<2> and PORTD<7:5> data latches. The
TRISC<2> and TRISD<7:5> bits must be cleared to
make the P1A, P1B, P1C and P1D pins outputs.
FULL-BRIDGE PWM OUTPUT
Forward Mode
Period
P1A
(2)
Duty Cycle
P1B(2)
P1C(2)
P1D(2)
(1)
(1)
Reverse Mode
Period
Duty Cycle
P1A(2)
P1B(2)
P1C(2)
P1D(2)
(1)
(1)
Note 1: At this time, the TMR2 register is equal to the PR2 register.
Note 2: Output signal is shown as active-high.
© 2008 Microchip Technology Inc.
DS39631E-page 153
PIC18F2420/2520/4420/4520
FIGURE 16-7:
EXAMPLE OF FULL-BRIDGE OUTPUT MODE APPLICATION
V+
PIC18F4X2X
FET
Driver
QC
QA
FET
Driver
P1A
Load
P1B
FET
Driver
P1C
FET
Driver
QD
QB
VP1D
16.4.5.1
Direction Change in Full-Bridge Mode
In the Full-Bridge Output mode, the P1M1 bit in the
CCP1CON register allows user to control the forward/
reverse direction. When the application firmware
changes this direction control bit, the module will
assume the new direction on the next PWM cycle.
Just before the end of the current PWM period, the
modulated outputs (P1B and P1D) are placed in their
inactive state, while the unmodulated outputs (P1A and
P1C) are switched to drive in the opposite direction.
This occurs in a time interval of 4 TOSC * (Timer2
Prescale Value) before the next PWM period begins.
The Timer2 prescaler will be either 1, 4 or 16, depending on the value of the T2CKPS<1:0> bits
(T2CON<1:0>). During the interval from the switch of
the unmodulated outputs to the beginning of the next
period, the modulated outputs (P1B and P1D) remain
inactive. This relationship is shown in Figure 16-8.
Note that in the Full-Bridge Output mode, the CCP1
module does not provide any dead-band delay. In general, since only one output is modulated at all times,
dead-band delay is not required. However, there is a
situation where a dead-band delay might be required.
This situation occurs when both of the following
conditions are true:
1.
2.
Figure 16-9 shows an example where the PWM
direction changes from forward to reverse at a near
100% duty cycle. At time t1, the outputs P1A and P1D
become inactive, while output P1C becomes active. In
this example, since the turn-off time of the power
devices is longer than the turn-on time, a shoot-through
current may flow through power devices, QC and QD
(see Figure 16-7), 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, one of the following requirements
must be met:
1.
2.
Reduce PWM for a 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.
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.
DS39631E-page 154
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 16-8:
PWM DIRECTION CHANGE
Period(1)
SIGNAL
Period
P1A (Active-High)
P1B (Active-High)
DC
P1C (Active-High)
(Note 2)
P1D (Active-High)
DC
Note 1: The direction bit in the CCP1 Control register (CCP1CON<7>) is written any time during the PWM cycle.
2: When changing directions, the P1A and P1C signals switch before the end of the current PWM cycle at intervals
of 4 TOSC, 16 TOSC or 64 TOSC, depending on the Timer2 prescaler value. The modulated P1B and P1D signals
are inactive at this time.
FIGURE 16-9:
PWM DIRECTION CHANGE AT NEAR 100% DUTY CYCLE
Forward Period
t1
Reverse Period
P1A(1)
P1B(1)
DC
P1C(1)
P1D(1)
DC
tON(2)
External Switch C(1)
tOFF(3)
External Switch D(1)
Potential
Shoot-Through
Current(1)
Note 1:
2:
3:
t = tOFF – tON(2,3)
All signals are shown as active-high.
tON is the turn-on delay of power switch, QC, and its driver.
tOFF is the turn-off delay of power switch, QD, and its driver.
© 2008 Microchip Technology Inc.
DS39631E-page 155
PIC18F2420/2520/4420/4520
16.4.6
Note:
PROGRAMMABLE DEAD-BAND
DELAY
Programmable dead-band delay is not
implemented in 28-pin devices with
standard CCP modules.
In half-bridge applications where all power switches are
modulated at the PWM frequency at all times, 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 (shootthrough current) may 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.
In the Half-Bridge Output 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 nonactive
state to the active state (see Figure 16-4 for illustration).
Bits, PDC<6:0>, of the PWM1CON register
(Register 16-2) set the delay period in terms of microcontroller instruction cycles (TCY or 4 TOSC). These bits
are not available on 28-pin devices as the standard CCP
module does not support half-bridge operation.
16.4.7
ENHANCED PWM AUTO-SHUTDOWN
When the CCP1 is programmed for any of the Enhanced
PWM modes, the active output pins may be configured
for auto-shutdown. Auto-shutdown immediately places
the Enhanced PWM output pins into a defined shutdown
state when a shutdown event occurs.
REGISTER 16-2:
A shutdown event can be caused by either of the
comparator modules, a low level on the Fault input pin
(FLT0) or any combination of these three sources. The
comparators may be used to monitor a voltage input
proportional to a current being monitored in the bridge
circuit. If the voltage exceeds a threshold, the
comparator switches state and triggers a shutdown.
Alternatively, a low digital signal on FLT0 can also trigger
a shutdown. The auto-shutdown feature can be disabled
by not selecting any auto-shutdown sources. The autoshutdown sources to be used are selected using the
ECCPAS<2:0> bits (ECCP1AS<6:4>).
When a shutdown occurs, the output pins are
asynchronously placed in their shutdown states,
specified by the PSSAC<1:0> and PSSBD<1:0> bits
(ECCPAS<2:0>). Each pin pair (P1A/P1C and P1B/
P1D) may be set to drive high, drive low or be tri-stated
(not driving). The ECCPASE bit (ECCP1AS<7>) is also
set to hold the Enhanced PWM outputs in their
shutdown states.
The ECCPASE bit is set by hardware when a shutdown
event occurs. If automatic restarts are not enabled, the
ECCPASE bit is cleared by firmware when the cause of
the shutdown clears. If automatic restarts are enabled,
the ECCPASE bit is automatically cleared when the
cause of the auto-shutdown has cleared.
If the ECCPASE bit is set when a PWM period begins,
the PWM outputs remain in their shutdown state for that
entire PWM period. When the ECCPASE bit is cleared,
the PWM outputs will return to normal operation at the
beginning of the next PWM period.
Note:
Writing to the ECCPASE bit is disabled
while a shutdown condition is active.
PWM1CON: PWM DEAD-BAND DELAY 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(1)
PDC5(1)
PDC4(1)
PDC3(1)
PDC2(1)
PDC1(1)
PDC0(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
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 in software to restart the PWM
bit 6-0
PDC6:PDC0: PWM Delay Count bits(1)
Delay time, in number of FOSC/4 (4 * TOSC) cycles, between the scheduled and actual time for a PWM
signal to transition to active.
Note 1:
Reserved on 28-pin devices; maintain these bits clear.
DS39631E-page 156
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 16-3:
ECCP1AS: ECCP 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(1)
PSSBD0(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
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
111 = FLT0 or Comparator 1 or Comparator 2
110 = FLT0 or Comparator 2
101 = FLT0 or Comparator 1
100 = FLT0
011 = Either Comparator 1 or 2
010 = Comparator 2 output
001 = Comparator 1 output
000 = Auto-shutdown is disabled
bit 3-2
PSSAC<1:0>: Pins A and C Shutdown State Control bits
1x = Pins A and C are tri-state (40/44-pin devices); PWM output is tri-state (28-pin devices)
01 = Drive Pins A and C to ‘1’
00 = Drive Pins A and C to ‘0’
bit 1-0
PSSBD<1:0>: Pins B and D Shutdown State Control bits(1)
1x = Pins B and D tri-state
01 = Drive Pins B and D to ‘1’
00 = Drive Pins B and D to ‘0’
Note 1:
Reserved on 28-pin devices; maintain these bits clear.
© 2008 Microchip Technology Inc.
DS39631E-page 157
PIC18F2420/2520/4420/4520
16.4.7.1
Auto-Shutdown and Automatic
Restart
The auto-shutdown feature can be configured to allow
automatic restarts of the module following a shutdown
event. This is enabled by setting the PRSEN bit of the
PWM1CON register (PWM1CON<7>).
In Shutdown mode with PRSEN = 1 (Figure 16-10), the
ECCPASE bit will remain set for as long as the cause
of the shutdown continues. When the shutdown condition clears, the ECCPASE bit is cleared. If PRSEN = 0
(Figure 16-11), once a shutdown condition occurs, the
ECCPASE bit will remain set until it is cleared by firmware. Once ECCPASE is cleared, the Enhanced PWM
will resume at the beginning of the next PWM period.
Note:
Writing to the ECCPASE bit is disabled
while a shutdown condition is active.
Independent of the PRSEN bit setting, if the autoshutdown source is one of the comparators, the
shutdown condition is a level. The ECCPASE bit
cannot be cleared as long as the cause of the shutdown
persists.
The Auto-Shutdown mode can be forced by writing a ‘1’
to the ECCPASE bit.
FIGURE 16-10:
16.4.8
START-UP CONSIDERATIONS
When the ECCP module is used in the PWM mode, the
application hardware must use the proper external pullup and/or pull-down resistors on the PWM output pins.
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 (CCP1CON<1:0>) 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 pins are
configured as outputs. Changing the polarity configuration while the PWM pins are configured as outputs 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 pins for output at the same time as
the ECCP module may cause damage to the application circuit. The ECCP module must be enabled in the
proper output mode and complete a full PWM cycle
before configuring the PWM pins as outputs. The completion of a full PWM cycle is indicated by the TMR2IF
bit being set as the second PWM period begins.
PWM AUTO-SHUTDOWN (PRSEN = 1, AUTO-RESTART ENABLED)
PWM Period
Shutdown Event
ECCPASE bit
PWM Activity
Normal PWM
Start of
PWM Period
FIGURE 16-11:
Shutdown
Shutdown
Event Occurs Event Clears
PWM
Resumes
PWM AUTO-SHUTDOWN (PRSEN = 0, AUTO-RESTART DISABLED)
PWM Period
Shutdown Event
ECCPASE bit
PWM Activity
Normal PWM
Start of
PWM Period
DS39631E-page 158
ECCPASE
Cleared by
Shutdown
Shutdown Firmware PWM
Event Occurs Event Clears
Resumes
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
16.4.9
SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the ECCP module for PWM operation:
1.
Configure the PWM pins, P1A and P1B (and
P1C and P1D, if used), as inputs by setting the
corresponding TRIS bits.
2. Set the PWM period by loading the PR2 register.
3. If auto-shutdown is required:
• Disable auto-shutdown (ECCPASE = 0)
• Configure source (FLT0, Comparator 1 or
Comparator 2)
• Wait for non-shutdown condition
4. Configure the ECCP module for the desired
PWM mode and configuration by loading the
CCP1CON register with the appropriate values:
• Select one of the available output
configurations and direction with the
P1M<1:0> bits.
• Select the polarities of the PWM output
signals with the CCP1M<3:0> bits.
5. Set the PWM duty cycle by loading the CCPR1L
register and CCP1CON<5:4> bits.
6. For Half-Bridge Output mode, set the deadband delay by loading PWM1CON<6:0> with
the appropriate value.
7. If auto-shutdown operation is required, load the
ECCP1AS register:
• Select the auto-shutdown sources using the
ECCPAS<2:0> bits.
• Select the shutdown states of the PWM
output pins using the PSSAC<1:0> and
PSSBD<1:0> bits.
• Set the ECCPASE bit (ECCP1AS<7>).
• Configure the comparators using the CMCON
register.
• Configure the comparator inputs as analog
inputs.
8. If auto-restart operation is required, set the
PRSEN bit (PWM1CON<7>).
9. Configure and start TMR2:
• Clear the TMR2 interrupt flag bit by clearing
the TMR2IF bit (PIR1<1>).
• Set the TMR2 prescale value by loading the
T2CKPS bits (T2CON<1:0>).
• Enable Timer2 by setting the TMR2ON bit
(T2CON<2>).
10. Enable PWM outputs after a new PWM cycle
has started:
• Wait until TMRx overflows (TMRxIF bit is set).
• Enable the CCP1/P1A, P1B, P1C and/or P1D
pin outputs by clearing the respective TRIS
bits.
• Clear the ECCPASE bit (ECCP1AS<7>).
© 2008 Microchip Technology Inc.
16.4.10
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 INTOSC
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.
16.4.10.1
Operation with Fail-Safe
Clock Monitor
If the Fail-Safe Clock Monitor is enabled, a clock failure
will force the device into the power-managed RC_RUN
mode and the OSCFIF bit (PIR2<7>) 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.
16.4.11
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.
DS39631E-page 159
PIC18F2420/2520/4420/4520
TABLE 16-3:
Name
INTCON
RCON
REGISTERS ASSOCIATED WITH ECCP MODULE AND TIMER1 TO TIMER3
Bit 7
Bit 6
GIE/GIEH PEIE/GIEL
IPEN
SBOREN
Reset
Values
on page
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
—
RI
TO
PD
POR
BOR
48
PIR1
PSPIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
IPR2
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
TRISB
PORTB Data Direction Register
52
TRISC
PORTC Data Direction Register
52
TRISD
PORTD Data Direction Register
52
TMR1L
Timer1 Register Low Byte
50
TMR1H
Timer1 Register High Byte
50
T1CON
TMR2
T2CON
RD16
T1RUN
T1CKPS1
T1CKPS0
T1OSCEN
T1SYNC
TMR1CS
TMR1ON
Timer2 Register
—
50
50
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
50
PR2
Timer2 Period Register
50
TMR3L
Timer3 Register Low Byte
51
TMR3H
Timer3 Register High Byte
T3CON
RD16
T3CCP2
51
T3CKPS1
T3CKPS0
T3CCP1
T3SYNC
TMR3CS
TMR3ON
51
CCPR1L
Capture/Compare/PWM Register 1 Low Byte
51
CCPR1H
Capture/Compare/PWM Register 1 High Byte
51
CCP1CON
ECCP1AS
PWM1CON
Legend:
Note 1:
P1M1
(1)
P1M0(1)
ECCPASE ECCPAS2
PRSEN
PDC6(1)
DC1B1
DC1B0
CCP1M3
CCP1M2
ECCPAS1
ECCPAS0
PSSAC1
PSSAC0
PDC5(1)
PDC4(1)
PDC3(1)
PDC2(1)
CCP1M1
CCP1M0
PSSBD1(1) PSSBD0(1)
PDC1(1)
PDC0(1)
51
51
51
— = unimplemented, read as ‘0’. Shaded cells are not used during ECCP operation.
These bits are unimplemented on 28-pin devices; always maintain these bits clear.
DS39631E-page 160
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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) – RC5/SDO
• Serial Data In (SDI) – RC4/SDI/SDA
• Serial Clock (SCK) – RC3/SCK/SCL
Additionally, a fourth pin may be used when in a Slave
mode of operation:
• Slave Select (SS) – RA5/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 three associated registers.
These include a status register (SSPSTAT) and two
control registers (SSPCON1 and SSPCON2). 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.
Additional details are provided under the individual
sections.
Write
SSPBUF reg
RC4/SDI/SDA
SSPSR reg
RC5/SDO
RA5/AN4/SS/
HLVDIN/C2OUT
Shift
Clock
bit 0
SS Control
Enable
Edge
Select
2
Clock Select
RC3/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
© 2008 Microchip Technology Inc.
DS39631E-page 161
PIC18F2420/2520/4420/4520
17.3.1
REGISTERS
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.
The MSSP module has four registers for SPI mode
operation. These are:
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.
• MSSP Control Register 1 (SSPCON1)
• MSSP Status Register (SSPSTAT)
• Serial Receive/Transmit Buffer Register
(SSPBUF)
• MSSP Shift Register (SSPSR) – Not directly
accessible
During transmission, the SSPBUF is not doublebuffered. A write to SSPBUF will write to both SSPBUF
and SSPSR.
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:
R/W-0
SMP
SSPSTAT: MSSP STATUS REGISTER (SPI MODE)
R/W-0
R-0
R-0
R-0
R-0
R-0
R-0
(1)
D/A
P
S
R/W
UA
BF
CKE
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 = Transmit occurs on transition from active to Idle clock state
0 = Transmit occurs on transition from Idle to active clock state
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 (SSPCON1<4>).
DS39631E-page 162
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 17-2:
R/W-0
WCOL
SSPCON1: MSSP CONTROL REGISTER 1 (SPI MODE)
R/W-0
R/W-0
(1)
(2)
SSPOV
SSPEN
R/W-0
CKP
R/W-0
SSPM3
(3)
R/W-0
SSPM2
(3)
R/W-0
SSPM1
(3)
R/W-0
SSPM0(3)
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
1 = The SSPxBUF register is written while it is still transmitting the previous word (must be cleared in
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 in software).
0 = No overflow
bit 5
SSPEN: Master Synchronous Serial Port Enable bit(2)
1 = Enables serial port and configures SCK, SDO, SDI and SS as serial port pins
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>: Master 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.
© 2008 Microchip Technology Inc.
DS39631E-page 163
PIC18F2420/2520/4420/4520
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
(SSPSTAT<0>) 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
EXAMPLE 17-1:
LOOP
Note:
will be ignored and the write collision detect bit, WCOL
(SSPCON1<7>), 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.
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 (SSPSTAT<0>), 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.
Note:
The SSPBUF register cannot be used with
read-modify-write instructions such as
BCF, BTFSC and COMF, etc.
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
To avoid lost data in Master mode, a read
of the SSPBUF must be performed to clear
the Buffer Full (BF) detect bit
(SSPSTAT<0>)
between
each
transmission.
DS39631E-page 164
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
17.3.3
ENABLING SPI I/O
17.3.4
To enable the serial port, MSSP Enable bit, SSPEN
(SSPCON1<5>), 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 TRISC<5> bit cleared
• SCK (Master mode) must have TRISC<3> bit
cleared
• SCK (Slave mode) must have TRISC<3> bit set
• SS must have TRISA<5> 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
© 2008 Microchip Technology Inc.
Shift Register
(SSPSR)
MSb
SCK
PROCESSOR 1
SDO
Serial Clock
LSb
SCK
PROCESSOR 2
DS39631E-page 165
PIC18F2420/2520/4420/4520
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 (SSPCON1<4>). 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 40 MHz) of
10.00 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
DS39631E-page 166
Next Q4 Cycle
after Q2↓
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 (SSPCON1<4>).
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: If the SPI is used in Slave mode with CKE
set, then the SS pin control must 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
© 2008 Microchip Technology Inc.
Next Q4 Cycle
after Q2↓
DS39631E-page 167
PIC18F2420/2520/4420/4520
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
DS39631E-page 168
Next Q4 Cycle
after Q2↓
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
17.3.8
OPERATION IN POWER-MANAGED
MODES
17.3.9
In SPI Master mode, module clocks may be operating
at a different speed than when in full-power mode; in
the case of Sleep mode, all clocks are halted.
In most Idle modes, a clock is provided to the peripherals. That clock should be from the primary clock
source, the secondary clock (Timer1 oscillator at
32.768 kHz) or the INTOSC source. See Section 2.7
“Clock Sources and Oscillator Switching” for
additional information.
In most cases, the speed that the master clocks SPI
data is not important; however, this should be
evaluated for each system.
If MSSP interrupts are enabled, they can wake the controller from Sleep mode, or one of the Idle modes, when
the master completes sending data. If an exit from
Sleep or Idle mode is not desired, MSSP interrupts
should be disabled.
If 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.
EFFECTS OF A RESET
A Reset disables the MSSP module and terminates the
current transfer.
17.3.10
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
0, 0
0
1
0, 1
0
0
1, 0
1
1
1, 1
1
0
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 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.
TABLE 17-2:
Name
REGISTERS ASSOCIATED WITH SPI 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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
(2)
TRISA6(2)
PORTA Data Direction Register
TRISA
TRISA7
TRISC
PORTC Data Direction Register
SSPBUF
MSSP Receive Buffer/Transmit Register
52
52
50
SSPCON1
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
50
SSPSTAT
SMP
CKE
D/A
P
S
R/W
UA
BF
50
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’.
© 2008 Microchip Technology Inc.
DS39631E-page 169
PIC18F2420/2520/4420/4520
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 modes.
Two pins are used for data transfer:
• Serial clock (SCL) – RC3/SCK/SCL
• Serial data (SDA) – RC4/SDI/SDA
The user must configure these pins as inputs or outputs
through the TRISC<4:3> bits.
FIGURE 17-7:
MSSP BLOCK DIAGRAM
(I2C MODE)
Internal
Data Bus
Read
Write
SSPBUF reg
RC3/SCK/SCL
Shift
Clock
MSb
LSb
Match Detect
Addr Match
SSPADD reg
Start and
Stop bit Detect
DS39631E-page 170
The MSSP module has six 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)
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.
SSPADD register holds the slave device address when
the MSSP is configured in I2C Slave mode. When the
MSSP is configured in Master mode, the lower seven
bits of SSPADD act as the Baud Rate Generator reload
value.
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.
SSPSR reg
RC4/SDI/
SDA
REGISTERS
During transmission, the SSPBUF is not doublebuffered. A write to SSPBUF will write to both SSPBUF
and SSPSR.
Set, Reset
S, P bits
(SSPSTAT reg)
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 17-3:
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.
© 2008 Microchip Technology Inc.
DS39631E-page 171
PIC18F2420/2520/4420/4520
REGISTER 17-4:
R/W-0
WCOL
SSPCON1: MSSP CONTROL REGISTER 1 (I2C™ MODE)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
SSPOV
SSPEN(1)
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 in 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 in
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 in
software)
0 = No overflow
In Transmit mode:
This is a “don’t care” bit in Transmit mode.
bit 5
SSPEN: Master Synchronous Serial Port Enable bit(1)
1 = Enables the serial port and configures the SDA and SCL pins as the serial port pins
0 = Disables serial port and configures these pins as I/O port pins
bit 4
CKP: SCK Release Control bit
In Slave mode:
1 = Releases 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>: Master Synchronous Serial Port Mode Select bits(2)
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.
Note 1:
When enabled, the SDA and SCL pins must be properly configured as inputs or outputs.
DS39631E-page 172
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 17-5:
SSPCON2: MSSP CONTROL REGISTER 2 (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
GCEN
ACKSTAT
ACKDT(2)
ACKEN(1)
RCEN(1)
PEN(1)
RSEN(1)
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 = Enables 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 = Initiates 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 = Initiates 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 = Initiates 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 = Initiates 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
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.
© 2008 Microchip Technology Inc.
DS39631E-page 173
PIC18F2420/2520/4420/4520
17.4.2
OPERATION
The MSSP module functions are enabled by setting the
MSSP Enable bit, SSPEN (SSPCON1<5>).
The SSPCON1 register allows control of the I 2C
operation. Four mode selection bits (SSPCON1<3:0>)
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 addressing)
I 2C Slave mode (10-bit addressing)
I 2C Slave mode (7-bit addressing) with Start and
Stop bit interrupts enabled
• I 2C Slave mode (10-bit addressing) 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 TRISC 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 (TRISC<4:3> set). 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 (PIR1<3>), 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 (PIR1<3>), is
set (interrupt is generated, if enabled) on the
falling edge of the ninth SCL pulse.
In 10-Bit Addressing 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 (SSPSTAT<2>), 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 Addressing mode 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 (SSPSTAT<0>), was set
before the transfer was received.
• The overflow bit, SSPOV (SSPCON2<6>), was
set before the transfer was received.
Addressing
6.
7.
8.
9.
Receive first (high) byte of address (bits, SSPIF,
BF and UA (SSPSTAT<1>), are set).
Update the SSPADD register with second (low)
byte of address (clears UA bit and releases the
SCL line).
Read the SSPBUF register (clears BF bit) and
clear flag bit, SSPIF.
Receive second (low) byte of address (bits,
SSPIF, BF and UA, are set).
Update the SSPADD register with the first (high)
byte of address. If match releases SCL line, this
will clear bit, UA.
Read the SSPBUF register (clears BF bit) 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 BF bit) 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.
DS39631E-page 174
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 (SSPSTAT<0>), is
set, or bit, SSPOV (SSPCON1<6>), is set.
An MSSP interrupt is generated for each data transfer
byte. Flag bit, SSPIF (PIR1<3>), must be cleared in
software. The SSPSTAT register is used to determine
the status of the byte.
If SEN is enabled (SSPCON2<0> = 1), RC3/SCK/SCL
will be held low (clock stretch) following each data
transfer. The clock must be released by setting bit,
CKP (SSPCON<4>). See Section 17.4.4 “Clock
Stretching” for more details.
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 the RC3/SCK/SCL pin 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 the RC3/SCK/SCL pin should be enabled by setting bit, CKP (SSPCON1<4>). 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, the RC3/SCK/SCL pin must be enabled by
setting bit, CKP.
An MSSP interrupt is generated for each data transfer
byte. The SSPIF bit must be cleared in 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.
© 2008 Microchip Technology Inc.
DS39631E-page 175
DS39631E-page 176
2
A6
3
4
A4
5
A3
Receiving Address
A5
6
A2
(CKP does not reset to ‘0’ when SEN = 0)
CKP (SSPCON1<4>)
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 in 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
PIC18F2420/2520/4420/4520
I2C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 7-BIT ADDRESSING)
© 2008 Microchip Technology Inc.
© 2008 Microchip Technology Inc.
1
CKP
2
A6
Data in
sampled
BF (SSPSTAT<0>)
SSPIF (PIR1<3>)
S
A7
3
A5
4
A4
5
A3
6
A2
Receiving Address
7
A1
8
R/W = 1
9
ACK
4
D4
5
D3
Cleared in software
3
D5
6
D2
SSPBUF is written in software
2
D6
CKP is set in software
Clear by reading
SCL held low
while CPU
responds to SSPIF
1
D7
Transmitting Data
7
8
D0
9
ACK
From SSPIF ISR
D1
1
D7
4
D4
5
D3
6
D2
CKP is set in software
7
8
D0
9
ACK
From SSPIF ISR
D1
Transmitting Data
Cleared in software
3
D5
SSPBUF is written in software
2
D6
P
FIGURE 17-9:
SCL
SDA
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I2C™ SLAVE MODE TIMING (TRANSMISSION, 7-BIT ADDRESSING)
DS39631E-page 177
DS39631E-page 178
2
1
3
1
4
1
5
0
7
A8
UA is set indicating that
the SSPADD needs to be
updated
8
9
(CKP does not reset to ‘0’ when SEN = 0)
CKP (SSPCON1<4>)
UA (SSPSTAT<1>)
SSPOV (SSPCON1<6>)
6
A9
SSPBUF is written with
contents of SSPSR
Cleared in 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 in software
3
A5
Dummy read of SSPBUF
to clear BF flag
1
A6
Receive Second Byte of Address
1
D7
4
5
6
Cleared in software
3
7
8
9
1
2
4
5
6
Cleared in 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
7
8
D1 D0
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
PIC18F2420/2520/4420/4520
I2C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 10-BIT ADDRESSING)
© 2008 Microchip Technology Inc.
© 2008 Microchip Technology Inc.
2
CKP (SSPCON1<4>)
UA (SSPSTAT<1>)
BF (SSPSTAT<0>)
(PIR1<3>)
SSPIF
1
S
SCL
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
Receive First Byte of Address
1
9
ACK
1
3
4
5
Cleared in 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 in software
1
1
5
0
6
8
9
ACK
R/W=1
1
2
4
5
6
CKP is set in software
9
P
Completion of
data transmission
clears BF flag
8
ACK
Bus master
terminates
transfer
CKP is automatically cleared in hardware, holding SCL low
7
D4 D3 D2 D1 D0
Cleared in 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
R/W = 0
Clock is held low until
update of SSPADD has
taken place
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I2C™ SLAVE MODE TIMING (TRANSMISSION, 10-BIT ADDRESSING)
DS39631E-page 179
PIC18F2420/2520/4420/4520
17.4.4
CLOCK STRETCHING
Both 7-Bit and 10-Bit Slave modes implement
automatic clock stretching during a transmit sequence.
The SEN bit (SSPCON2<0>) 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 in 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
Interrupt Service Routine (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 receive 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 in 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 transmit 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 in 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.
DS39631E-page 180
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
FIGURE 17-12:
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).
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
SSPCONx
© 2008 Microchip Technology Inc.
DS39631E-page 181
DS39631E-page 182
CKP (SSPCON1<4>)
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 in 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
PIC18F2420/2520/4420/4520
I2C™ SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 7-BIT ADDRESSING)
© 2008 Microchip Technology Inc.
© 2008 Microchip Technology Inc.
2
1
3
1
4
1
5
0
CKP (SSPCON1<4>)
UA (SSPSTAT<1>)
SSPOV (SSPCON1<6>)
6
7
A9 A8
8
UA is set indicating that
the SSPADD needs to be
updated
SSPBUF is written with
contents of SSPSR
Cleared in 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 in 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
Cleared in software
3
D3 D2
7
8
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.
9
ACK
1
4
5
6
Cleared in software
3
CKP written to ‘1’
in 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 hardware when
SSPADD is updated with high
byte of address after falling edge
of ninth clock
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
7
8
9
Bus master
terminates
transfer
P
SSPOV is set
because SSPBUF is
still full. ACK is not sent.
D1 D0
ACK
Clock is not held low
because ACK = 1
FIGURE 17-14:
SDA
Receive First Byte of Address
Clock is held low until
update of SSPADD has
taken place
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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 is set (SSPSTAT<1>). If the general call address is
sampled when the GCEN bit is set, while the slave is
configured in 10-Bit Addressing 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 General Call Enable bit, GCEN, is enabled (SSPCON2<7>
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 ADDRESSING MODE)
Address is compared to General Call Address
after ACK, set interrupt
R/W = 0
ACK D7
General Call Address
SDA
SCL
S
1
2
3
4
5
6
7
8
9
1
Receiving Data
ACK
D6
D5
D4
D3
D2
D1
D0
2
3
4
5
6
7
8
9
SSPIF
BF (SSPSTAT<0>)
Cleared in software
SSPBUF is read
SSPOV (SSPCON1<6>)
‘0’
GCEN (SSPCON2<7>)
‘1’
DS39631E-page 184
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 MSSP Interrupt
Flag bit, SSPIF, to be set (MSSP 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<6:0>
Write
SSPBUF
SDA
Baud
Rate
Generator
Shift
Clock
SDA In
SCL In
Bus Collision
© 2008 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)
DS39631E-page 185
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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.
DS39631E-page 186
A typical transmit sequence would go as follows:
1.
The user generates a Start condition by setting
the Start Enable bit, SEN (SSPCON2<0>).
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
SSPCON2 register (SSPCON2<6>).
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
SSPCON2 register (SSPCON2<6>).
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 Stop Enable bit, PEN (SSPCON2<2>).
12. Interrupt is generated once the Stop condition is
complete.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
17.4.7
BAUD RATE
2
In I C Master mode, the Baud Rate Generator (BRG)
reload value is placed in the lower 7 bits of 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.
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.
BAUD RATE GENERATOR BLOCK DIAGRAM
SSPM<3:0>
SSPM<3:0>
Reload
SCL
Control
CLKO
TABLE 17-3:
Note 1:
SSPADD<6:0>
Reload
BRG Down Counter
FOSC/4
I2C™ CLOCK RATE W/BRG
FCY
FCY * 2
BRG Value
FSCL
(2 Rollovers of BRG)
10 MHz
20 MHz
18h
400 kHz(1)
10 MHz
20 MHz
1Fh
312.5 kHz
10 MHz
20 MHz
63h
100 kHz
4 MHz
8 MHz
09h
400 kHz(1)
4 MHz
8 MHz
0Ch
308 kHz
4 MHz
8 MHz
27h
100 kHz
1 MHz
2 MHz
02h
333 kHz(1)
1 MHz
2 MHz
09h
100 kHz
1 MHz
2 MHz
00h
1 MHz(1)
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.
© 2008 Microchip Technology Inc.
DS39631E-page 187
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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
FIGURE 17-18:
SCL pin is sampled high, the Baud Rate Generator is
reloaded with the contents of SSPADD<6:0> 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).
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
DS39631E-page 188
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
17.4.8
I2C MASTER MODE START
CONDITION TIMING
Note:
To initiate a Start condition, the user sets the Start
Enable bit, SEN (SSPCON2<0>). 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 (SSPSTAT<3>) to be set. Following this, the
Baud Rate Generator is reloaded with the contents of
SSPADD<6:0> and resumes its count. When the Baud
Rate Generator times out (TBRG), the SEN bit
(SSPCON2<0>) 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
Write to SEN bit occurs here
Set S bit (SSPSTAT<3>)
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
© 2008 Microchip Technology Inc.
DS39631E-page 189
PIC18F2420/2520/4420/4520
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
(SSPCON2<1>) 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<6:0> 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 (SSPCON2<1>) 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 (SSPSTAT<3>) 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
WCOL Status Flag
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).
Because queueing of events is not
allowed, writing of the lower 5 bits of
SSPCON2 is disabled until the Repeated
Start condition is complete.
Note:
FIGURE 17-20:
REPEATED START CONDITION WAVEFORM
Write to SSPCON2
occurs here.
SDA = 1,
SCL (no change).
S bit set by hardware
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
DS39631E-page 190
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
(SSPCON2<6>). 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
17.4.10.3
ACKSTAT Status Flag
In Transmit mode, the ACKSTAT bit (SSPCON2<6>) 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 (SSPCON2<3>).
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 bit, ACKEN
(SSPCON2<4>).
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).
In Transmit mode, the BF bit (SSPSTAT<0>) is set
when the CPU writes to SSPBUF and is cleared when
all 8 bits are shifted out.
17.4.10.2
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 in software.
© 2008 Microchip Technology Inc.
DS39631E-page 191
DS39631E-page 192
S
R/W
PEN
SEN
BF (SSPSTAT<0>)
SSPIF
SCL
SDA
A6
A5
A4
A3
A2
A1
3
4
5
Cleared in 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 in software
Cleared in software service routine
from MSSP interrupt
2
D6
Transmitting Data or Second Half
of 10-Bit Address
From slave, clear ACKSTAT bit SSPCON2<6>
P
Cleared in software
9
ACK
ACKSTAT in
SSPCON2 = 1
FIGURE 17-21:
SEN = 0
Write SSPCON2<0> SEN = 1
Start condition begins
PIC18F2420/2520/4420/4520
I 2C MASTER MODE WAVEFORM (TRANSMISSION, 7 OR 10-BIT ADDRESSING)
© 2008 Microchip Technology Inc.
© 2008 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
Cleared in software
3
6
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 in 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
Bus master
terminates
transfer
Set P bit
(SSPSTAT<4>)
and SSPIF
Set SSPIF interrupt
at end of Acknowledge
sequence
P
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 in software
Set SSPIF interrupt
at end of receive
4
Cleared in 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
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I 2C MASTER MODE WAVEFORM (RECEPTION, 7-BIT ADDRESSING)
DS39631E-page 193
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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 (SSPCON2<2>). 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
(SSPSTAT<4>) 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
(SSPCON2<4>). 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.
DS39631E-page 194
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 (SSPSTAT<4>) is set, or the
bus is Idle, with both the S and P bits clear. When the
bus is busy, enabling the MSSP 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 in
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
© 2008 Microchip Technology Inc.
DS39631E-page 195
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17.4.17.1
Bus Collision During a Start
Condition
During a Start condition, a bus collision occurs if:
a)
b)
SDA or SCL is 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<6:0>
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.
MSSP 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 in software
S
SSPIF
SSPIF and BCLIF are
cleared in software
DS39631E-page 196
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
in 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
© 2008 Microchip Technology Inc.
Interrupts cleared
in software
DS39631E-page 197
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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<6:0> 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 in 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
in software
RSEN
S
‘0’
SSPIF
DS39631E-page 198
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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<6:0>
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
SDA sampled
low after TBRG,
set BCLIF
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’
© 2008 Microchip Technology Inc.
DS39631E-page 199
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NOTES:
DS39631E-page 200
© 2008 Microchip Technology Inc.
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18.0
ENHANCED UNIVERSAL
SYNCHRONOUS
ASYNCHRONOUS RECEIVER
TRANSMITTER (EUSART)
The Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) module is one of the
two serial I/O modules. (Generically, the USART is also
known as a Serial Communications Interface or SCI.)
The EUSART can be configured as a full-duplex
asynchronous system that can communicate with
peripheral devices, such as CRT terminals and
personal computers. It can also be configured as a halfduplex, synchronous system that can communicate
with peripheral devices, such as A/D or D/A integrated
circuits, serial EEPROMs, etc.
The Enhanced USART module implements additional
features, including automatic baud rate detection and
calibration, automatic wake-up on Sync Break reception and 12-bit Break character transmit. These make it
ideally suited for use in Local Interconnect Network bus
(LIN bus) systems.
The pins of the Enhanced USART are multiplexed
with PORTC. In order to configure RC6/TX/CK and
RC7/RX/DT as an EUSART:
• bit SPEN (RCSTA<7>) must be set (= 1)
• bit TRISC<7> must be set (= 1)
• bit TRISC<6> must be set (= 1)
Note:
The EUSART control will automatically
reconfigure the pin from input to output as
needed.
The operation of the Enhanced USART module is
controlled through three registers:
• Transmit Status and Control (TXSTA)
• Receive Status and Control (RCSTA)
• Baud Rate Control (BAUDCON)
These are detailed on the following pages in
Register 18-1, Register 18-2 and Register 18-3,
respectively.
The EUSART can be configured in the following
modes:
• Asynchronous (full duplex) with:
- Auto-wake-up on character reception
- Auto-baud calibration
- 12-bit Break character transmission
• Synchronous – Master (half duplex) with
selectable clock polarity
• Synchronous – Slave (half duplex) with selectable
clock polarity
© 2008 Microchip Technology Inc.
DS39631E-page 201
PIC18F2420/2520/4420/4520
REGISTER 18-1:
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: 9th Bit of Transmit Data
Can be address/data bit or a parity bit.
Note 1:
SREN/CREN overrides TXEN in Sync mode.
DS39631E-page 202
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 18-2:
RCSTA: RECEIVE STATUS AND CONTROL REGISTER
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, enables interrupt and loads 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 9-Bit (RX9 = 0):
Don’t care.
bit 2
FERR: Framing Error bit
1 = Framing error (can be cleared by reading RCREG register and receiving 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: 9th Bit of Received Data
This can be address/data bit or a parity bit and must be calculated by user firmware.
© 2008 Microchip Technology Inc.
DS39631E-page 203
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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
RXDTP
TXCKP
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 Acquisition Rollover Status bit
1 = A BRG rollover has occurred during Auto-Baud Rate Detect mode (must be cleared in software)
0 = No BRG rollover has occurred
bit 6
RCIDL: Receive Operation Idle Status bit
1 = Receive operation is Idle
0 = Receive operation is active
bit 5
RXDTP: 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
TXCKP: Clock and Data Polarity Select bit
Asynchronous mode:
1 = Idle state for transmit (TX) is a low level
0 = Idle state for transmit (TX) is a high level
Synchronous mode:
1 = Idle state for clock (CK) is a high level
0 = Idle state for clock (CK) is a low level
bit 3
BRG16: 16-Bit Baud Rate Register Enable bit
1 = 16-bit Baud Rate Generator – SPBRGH and SPBRG
0 = 8-bit Baud Rate Generator – SPBRG only (Compatible mode), SPBRGH value ignored
bit 2
Unimplemented: Read as ‘0’
bit 1
WUE: Wake-up Enable bit
Asynchronous mode:
1 = EUSART will continue to sample the RX pin – interrupt generated on falling edge; bit cleared in
hardware on following rising edge
0 = RX pin not monitored or rising edge detected
Synchronous mode:
Unused in this mode.
bit 0
ABDEN: Auto-Baud Detect Enable bit
Asynchronous mode:
1 = Enable baud rate measurement on the next character. Requires reception of a Sync field (55h);
cleared in hardware upon completion.
0 = Baud rate measurement disabled or completed
Synchronous mode:
Unused in this mode.
DS39631E-page 204
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.1
Baud Rate Generator (BRG)
The BRG is a dedicated, 8-bit or 16-bit generator that
supports both the Asynchronous and Synchronous
modes of the EUSART. By default, the BRG operates
in 8-bit mode; setting the BRG16 bit (BAUDCON<3>)
selects 16-bit mode.
The SPBRGH:SPBRG register pair controls the period
of a free-running timer. In Asynchronous mode, bits,
BRGH (TXSTA<2>) and BRG16 (BAUDCON<3>), also
control the baud rate. In Synchronous mode, BRGH is
ignored. Table 18-1 shows the formula for computation
of the baud rate for different EUSART modes which
only apply in Master mode (internally generated clock).
Given the desired baud rate and FOSC, the nearest
integer value for the SPBRGH:SPBRG registers can be
calculated using the formulas in Table 18-1. From this,
the error in baud rate can be determined. An example
calculation is shown in Example 18-1. Typical baud
rates and error values for the various Asynchronous
modes are shown in Table 18-2. It may be
TABLE 18-1:
advantageous to use the high baud rate (BRGH = 1) or
the 16-bit BRG to reduce the baud rate error, or
achieve a slow baud rate for a fast oscillator frequency.
Writing a new value to the SPBRGH:SPBRG registers
causes the BRG timer to be reset (or cleared). This
ensures the BRG does not wait for a timer overflow
before outputting the new baud rate.
18.1.1
OPERATION IN POWER-MANAGED
MODES
The device clock is used to generate the desired baud
rate. When one of the power-managed modes is
entered, the new clock source may be operating at a
different frequency. This may require an adjustment to
the value in the SPBRG register pair.
18.1.2
SAMPLING
The data on the RX pin is sampled three times by a
majority detect circuit to determine if a high or a low
level is present at the RX pin.
BAUD RATE FORMULAS
Configuration Bits
BRG/EUSART Mode
Baud Rate Formula
8-Bit/Asynchronous
FOSC/[64 (n + 1)]
SYNC
BRG16
BRGH
0
0
0
0
0
1
8-Bit/Asynchronous
0
1
0
16-Bit/Asynchronous
0
1
1
16-Bit/Asynchronous
1
0
x
8-Bit/Synchronous
1
1
x
16-Bit/Synchronous
FOSC/[16 (n + 1)]
FOSC/[4 (n + 1)]
Legend: x = Don’t care, n = value of SPBRGH:SPBRG register pair
© 2008 Microchip Technology Inc.
DS39631E-page 205
PIC18F2420/2520/4420/4520
EXAMPLE 18-1:
CALCULATING BAUD RATE ERROR
For a device with FOSC of 16 MHz, desired baud rate of 9600, Asynchronous mode, 8-bit BRG:
Desired Baud Rate
= FOSC/(64 ([SPBRGH:SPBRG] + 1))
Solving for SPBRGH:SPBRG:
X
= ((FOSC/Desired Baud Rate)/64) – 1
= ((16000000/9600)/64) – 1
= [25.042] = 25
Calculated Baud Rate = 16000000/(64 (25 + 1))
= 9615
Error
= (Calculated Baud Rate – Desired Baud Rate)/Desired Baud Rate
= (9615 – 9600)/9600 = 0.16%
TABLE 18-2:
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
51
RCSTA
SPEN
Name
BAUDCON ABDOVF
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
51
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
51
SPBRGH
EUSART Baud Rate Generator Register High Byte
51
SPBRG
EUSART Baud Rate Generator Register Low Byte
51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the BRG.
DS39631E-page 206
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 18-3:
BAUD RATES FOR ASYNCHRONOUS MODES
SYNC = 0, BRGH = 0, BRG16 = 0
BAUD
RATE
(K)
FOSC = 40.000 MHz
FOSC = 20.000 MHz
SPBRG
Value
Actual
Rate
(K)
SPBRG
Value
FOSC = 10.000 MHz
Actual
Rate
(K)
SPBRG
Value
FOSC = 8.000 MHz
Actual
Rate
(K)
SPBRG
Value
Actual
Rate
(K)
%
Error
0.3
—
—
—
—
—
—
—
—
—
—
—
—
1.2
—
—
—
1.221
1.73
255
1.202
0.16
129
1.201
-0.16
103
2.4
2.441
1.73
255
2.404
0.16
129
2.404
0.16
64
2.403
-0.16
51
9.6
9.615
0.16
64
9.766
1.73
31
9.766
1.73
15
9.615
-0.16
12
19.2
19.531
1.73
31
19.531
1.73
15
19.531
1.73
7
—
—
—
57.6
56.818
-1.36
10
62.500
8.51
4
52.083
-9.58
2
—
—
—
115.2
125.000
8.51
4
104.167
-9.58
2
78.125
-32.18
1
—
—
—
(decimal)
%
Error
(decimal)
%
Error
(decimal)
%
Error
(decimal)
SYNC = 0, BRGH = 0, BRG16 = 0
BAUD
RATE
(K)
FOSC = 4.000 MHz
FOSC = 2.000 MHz
(decimal)
0.16
207
0.300
-0.16
103
0.300
-0.16
51
0.16
51
1.201
-0.16
25
1.201
-0.16
12
2.404
0.16
25
2.403
-0.16
12
—
—
—
9.6
8.929
-6.99
6
—
—
—
—
—
—
19.2
20.833
8.51
2
—
—
—
—
—
—
%
Error
0.3
0.300
1.2
1.202
2.4
SPBRG
Value
%
Error
SPBRG
Value
FOSC = 1.000 MHz
Actual
Rate
(K)
Actual
Rate
(K)
(decimal)
Actual
Rate
(K)
%
Error
SPBRG
Value
(decimal)
57.6
62.500
8.51
0
—
—
—
—
—
—
115.2
62.500
-45.75
0
—
—
—
—
—
—
SYNC = 0, BRGH = 1, BRG16 = 0
BAUD
RATE
(K)
FOSC = 40.000 MHz
FOSC = 20.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
—
—
—
—
—
—
—
—
—
9.766
1.73
255
Actual
Rate
(K)
%
Error
0.3
—
1.2
—
2.4
9.6
SPBRG
Value
SPBRG
Value
FOSC = 10.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
—
—
—
—
—
—
—
—
—
9.615
0.16
SPBRG
Value
FOSC = 8.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
SPBRG
Value
—
—
—
—
—
—
—
—
—
2.441
1.73
255
2.403
-0.16
207
129
9.615
0.16
64
9.615
-0.16
51
25
(decimal)
—
19.2
19.231
0.16
129
19.231
0.16
64
19.531
1.73
31
19.230
-0.16
57.6
58.140
0.94
42
56.818
-1.36
21
56.818
-1.36
10
55.555
3.55
8
115.2
113.636
-1.36
21
113.636
-1.36
10
125.000
8.51
4
—
—
—
SYNC = 0, BRGH = 1, BRG16 = 0
BAUD
RATE
(K)
FOSC = 4.000 MHz
Actual
Rate
(K)
%
Error
FOSC = 2.000 MHz
SPBRG
Value
(decimal)
Actual
Rate
(K)
%
Error
SPBRG
Value
(decimal)
FOSC = 1.000 MHz
Actual
Rate
(K)
%
Error
SPBRG
Value
(decimal)
0.3
—
—
—
—
—
—
0.300
-0.16
207
1.2
1.202
0.16
207
1.201
-0.16
103
1.201
-0.16
51
2.4
2.404
0.16
103
2.403
-0.16
51
2.403
-0.16
25
9.6
9.615
0.16
25
9.615
-0.16
12
—
—
—
19.2
19.231
0.16
12
—
—
—
—
—
—
57.6
62.500
8.51
3
—
—
—
—
—
—
115.2
125.000
8.51
1
—
—
—
—
—
—
© 2008 Microchip Technology Inc.
DS39631E-page 207
PIC18F2420/2520/4420/4520
TABLE 18-3:
BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 0, BRG16 = 1
BAUD
RATE
(K)
FOSC = 40.000 MHz
Actual
Rate
(K)
%
Error
FOSC = 20.000 MHz
SPBRG
Value
(decimal)
Actual
Rate
(K)
%
Error
FOSC = 10.000 MHz
(decimal)
Actual
Rate
(K)
SPBRG
Value
%
Error
FOSC = 8.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
SPBRG
Value
SPBRG
Value
(decimal)
0.3
0.300
0.00
8332
0.300
0.02
4165
0.300
0.02
2082
0.300
-0.04
1.2
1.200
0.02
2082
1.200
-0.03
1041
1.200
-0.03
520
1.201
-0.16
1665
415
2.4
2.402
0.06
1040
2.399
-0.03
520
2.404
0.16
259
2.403
-0.16
207
9.6
9.615
0.16
259
9.615
0.16
129
9.615
0.16
64
9.615
-0.16
51
25
19.2
19.231
0.16
129
19.231
0.16
64
19.531
1.73
31
19.230
-0.16
57.6
58.140
0.94
42
56.818
-1.36
21
56.818
-1.36
10
55.555
3.55
8
115.2
113.636
-1.36
21
113.636
-1.36
10
125.000
8.51
4
—
—
—
SYNC = 0, BRGH = 0, BRG16 = 1
BAUD
RATE
(K)
FOSC = 4.000 MHz
FOSC = 2.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
0.04
832
0.300
0.16
207
1.201
2.404
0.16
103
9.6
9.615
0.16
19.2
19.231
57.6
62.500
115.2
125.000
FOSC = 1.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
-0.16
415
0.300
-0.16
-0.16
103
1.201
-0.16
51
2.403
-0.16
51
2.403
-0.16
25
25
9.615
-0.16
12
—
—
—
0.16
12
—
—
—
—
—
—
8.51
3
—
—
—
—
—
—
8.51
1
—
—
—
—
—
—
Actual
Rate
(K)
%
Error
0.3
0.300
1.2
1.202
2.4
SPBRG
Value
SPBRG
Value
SPBRG
Value
(decimal)
207
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1
BAUD
RATE
(K)
FOSC = 40.000 MHz
FOSC = 20.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
0.00
33332
0.300
0.00
8332
1.200
0.02
4165
Actual
Rate
(K)
%
Error
0.3
0.300
1.2
1.200
2.4
2.400
SPBRG
Value
FOSC = 10.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
0.00
16665
0.300
0.02
4165
1.200
2.400
0.02
2082
2.402
SPBRG
Value
FOSC = 8.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
0.00
8332
0.300
-0.01
6665
0.02
2082
1.200
-0.04
1665
0.06
1040
2.400
-0.04
832
SPBRG
Value
SPBRG
Value
(decimal)
9.6
9.606
0.06
1040
9.596
-0.03
520
9.615
0.16
259
9.615
-0.16
207
19.2
19.193
-0.03
520
19.231
0.16
259
19.231
0.16
129
19.230
-0.16
103
57.6
57.803
0.35
172
57.471
-0.22
86
58.140
0.94
42
57.142
0.79
34
115.2
114.943
-0.22
86
116.279
0.94
42
113.636
-1.36
21
117.647
-2.12
16
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1
BAUD
RATE
(K)
0.3
1.2
FOSC = 4.000 MHz
Actual
Rate
(K)
%
Error
0.300
1.200
0.01
0.04
FOSC = 2.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
3332
832
0.300
1.201
-0.04
-0.16
SPBRG
Value
FOSC = 1.000 MHz
(decimal)
Actual
Rate
(K)
%
Error
1665
415
0.300
1.201
-0.04
-0.16
832
207
103
SPBRG
Value
SPBRG
Value
(decimal)
2.4
2.404
0.16
415
2.403
-0.16
207
2.403
-0.16
9.6
9.615
0.16
103
9.615
-0.16
51
9.615
-0.16
25
19.2
19.231
0.16
51
19.230
-0.16
25
19.230
-0.16
12
57.6
58.824
2.12
16
55.555
3.55
8
—
—
—
115.2
111.111
-3.55
8
—
—
—
—
—
—
DS39631E-page 208
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.1.3
AUTO-BAUD RATE DETECT
The Enhanced USART module supports the automatic
detection and calibration of baud rate. This feature is
active only in Asynchronous mode and while the WUE
bit is clear.
Note 1: If the WUE bit is set with the ABDEN bit,
Auto-Baud Rate Detection will occur on
the byte following the Break character.
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
due to bit error rates. Overall system timing and communication baud rates must
be taken into consideration when using the
Auto-Baud Rate Detection feature.
The automatic baud rate measurement sequence
(Figure 18-1) begins whenever a Start bit is received
and the ABDEN bit is set. The calculation is
self-averaging.
In the Auto-Baud Rate 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. In
ABD mode, the internal Baud Rate Generator is used
as a counter to time the bit period of the incoming serial
byte stream.
Once the ABDEN bit is set, the state machine will clear
the BRG and look for a Start bit. The Auto-Baud Rate
Detect must receive a byte with the value 55h (ASCII
“U”, which is also the LIN bus Sync character) in order to
calculate the proper bit rate. The measurement is taken
over both a low and a high bit time in order to minimize
any effects caused by asymmetry of the incoming signal.
After a Start bit, the SPBRG begins counting up, using
the preselected clock source on the first rising edge of
RX. After eight bits on the RX pin or the fifth rising edge,
an accumulated value totalling the proper BRG period is
left in the SPBRGH:SPBRG register pair. Once the 5th
edge is seen (this should correspond to the Stop bit), the
ABDEN bit is automatically cleared.
If a rollover of the BRG occurs (an overflow from FFFFh
to 0000h), the event is trapped by the ABDOVF status
bit (BAUDCON<7>). It is set in hardware by BRG rollovers and can be set or cleared by the user in software.
ABD mode remains active after rollover events and the
ABDEN bit remains set (Figure 18-2).
TABLE 18-4:
BRG COUNTER
CLOCK RATES
BRG16
BRGH
BRG Counter Clock
0
0
FOSC/512
0
1
FOSC/128
1
0
FOSC/128
1
1
FOSC/32
Note:
During the ABD sequence, SPBRG and
SPBRGH are both used as a 16-bit counter,
independent of BRG16 setting.
18.1.3.1
ABD and EUSART Transmission
Since the BRG clock is reversed during ABD acquisition, the EUSART transmitter cannot be used during
ABD. This means that whenever the ABDEN bit is set,
TXREG cannot be written to. Users should also ensure
that ABDEN does not become set during a transmit
sequence. Failing to do this may result in unpredictable
EUSART operation.
While calibrating the baud rate period, the BRG registers are clocked at 1/8th the preconfigured clock rate.
Note that the BRG clock will be configured by the
BRG16 and BRGH bits. Independent of the BRG16 bit
setting, both the SPBRG and SPBRGH will be used as
a 16-bit counter. This allows the user to verify that no
carry occurred for 8-bit modes by checking for 00h in
the SPBRGH register. Refer to Table 18-4 for counter
clock rates to the BRG.
While the ABD sequence takes place, the EUSART
state machine is held in Idle. The RCIF interrupt is set
once the fifth rising edge on RX is detected. The value
in the RCREG needs to be read to clear the RCIF
interrupt. The contents of RCREG should be discarded.
© 2008 Microchip Technology Inc.
DS39631E-page 209
PIC18F2420/2520/4420/4520
FIGURE 18-1:
BRG Value
AUTOMATIC BAUD RATE CALCULATION
XXXXh
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
RCIF bit
(Interrupt)
Read
RCREG
SPBRG
XXXXh
1Ch
SPBRGH
XXXXh
00h
Note: The ABD sequence requires the EUSART module to be configured in Asynchronous mode and WUE = 0.
FIGURE 18-2:
BRG OVERFLOW SEQUENCE
BRG Clock
ABDEN bit
RX pin
Start
Bit 0
ABDOVF bit
FFFFh
BRG Value
DS39631E-page 210
XXXXh
0000h
0000h
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.2
Once the TXREG register transfers the data to the TSR
register (occurs in one TCY), the TXREG register is empty
and the TXIF flag bit (PIR1<4>) is set. This interrupt can
be enabled or disabled by setting or clearing the interrupt
enable bit, TXIE (PIE1<4>). TXIF will be set regardless of
the state of TXIE; it cannot be cleared in software. TXIF
is also not cleared immediately upon loading TXREG, but
becomes valid in the second instruction cycle following
the load instruction. Polling TXIF immediately following a
load of TXREG will return invalid results.
EUSART Asynchronous Mode
The Asynchronous mode of operation is selected by
clearing the SYNC bit (TXSTA<4>). In this mode, the
EUSART uses standard Non-Return-to-Zero (NRZ) format (one Start bit, eight or nine data bits and one Stop
bit). The most common data format is 8 bits. An on-chip,
dedicated 8-bit/16-bit Baud Rate Generator can be used
to derive standard baud rate frequencies from the
oscillator.
The EUSART transmits and receives the LSb first. The
EUSART’s transmitter and receiver are functionally
independent but use the same data format and baud
rate. The Baud Rate Generator produces a clock, either
x16 or x64 of the bit shift rate depending on the BRGH
and BRG16 bits (TXSTA<2> and BAUDCON<3>). Parity
is not supported by the hardware but can be
implemented in software and stored as the 9th data bit.
While TXIF indicates the status of the TXREG register,
another bit, TRMT (TXSTA<1>), shows the status of
the TSR register. TRMT is a read-only bit which is set
when the TSR register is empty. No interrupt logic is
tied to this bit so the user has to poll this bit in order to
determine if the TSR register is empty.
Note 1: The TSR register is not mapped in data
memory so it is not available to the user.
When operating in Asynchronous mode, the EUSART
module consists of the following important elements:
•
•
•
•
•
•
•
2: Flag bit, TXIF, is set when enable bit,
TXEN, is set.
Baud Rate Generator
Sampling Circuit
Asynchronous Transmitter
Asynchronous Receiver
Auto-Wake-up on Sync Break Character
12-Bit Break Character Transmit
Auto-Baud Rate Detection
18.2.1
To set up an Asynchronous Transmission:
1.
2.
EUSART ASYNCHRONOUS
TRANSMITTER
3.
4.
The EUSART transmitter block diagram is shown in
Figure 18-3. The heart of the transmitter is the Transmit
(Serial) Shift Register (TSR). The Shift register obtains
its data from the Read/Write Transmit Buffer register,
TXREG. The TXREG register is loaded with data in
software. The TSR register is not loaded until the Stop
bit has been transmitted from the previous load. As
soon as the Stop bit is transmitted, the TSR is loaded
with new data from the TXREG register (if available).
FIGURE 18-3:
5.
6.
7.
8.
Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
Enable the asynchronous serial port by clearing
bit, SYNC, and setting bit, SPEN.
If interrupts are desired, set enable bit, TXIE.
If 9-bit transmission is desired, set transmit bit,
TX9. Can be used as address/data bit.
Enable the transmission by setting bit, TXEN,
which will also set bit, TXIF.
If 9-bit transmission is selected, the ninth bit
should be loaded in bit, TX9D.
Load data to the TXREG register (starts
transmission).
If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
EUSART TRANSMIT BLOCK DIAGRAM
Data Bus
TXIF
TXREG Register
TXIE
8
MSb
(8)
LSb
• • •
Pin Buffer
and Control
0
TSR Register
TX pin
Interrupt
TXEN
Baud Rate CLK
TRMT
BRG16
SPBRGH
SPBRG
Baud Rate Generator
© 2008 Microchip Technology Inc.
SPEN
TX9
TX9D
DS39631E-page 211
PIC18F2420/2520/4420/4520
FIGURE 18-4:
ASYNCHRONOUS TRANSMISSION
Write to TXREG
Word 1
BRG Output
(Shift Clock)
TX (pin)
Start bit
bit 0
bit 1
bit 7/8
Stop bit
Word 1
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
1 TCY
Word 1
Transmit Shift Reg
TRMT bit
(Transmit Shift
Reg. Empty Flag)
FIGURE 18-5:
ASYNCHRONOUS TRANSMISSION (BACK TO BACK)
Write to TXREG
Word 2
Word 1
BRG Output
(Shift Clock)
TX (pin)
Start bit
bit 0
bit 1
1 TCY
TXIF bit
(Interrupt Reg. Flag)
bit 7/8
Stop bit
Start bit
bit 0
Word 2
Word 1
1 TCY
Word 1
Transmit Shift Reg.
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 2
Transmit Shift Reg.
Note: This timing diagram shows two consecutive transmissions.
TABLE 18-5:
Name
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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
51
RCSTA
TXREG
EUSART Transmit Register
51
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
51
BAUDCON
ABDOVF
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
51
SPBRGH
EUSART Baud Rate Generator Register High Byte
51
SPBRG
EUSART Baud Rate Generator Register Low Byte
51
TXSTA
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous transmission.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
DS39631E-page 212
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.2.2
EUSART ASYNCHRONOUS
RECEIVER
18.2.3
The receiver block diagram is shown in Figure 18-6.
The data is received on the RX pin and drives the data
recovery block. The data recovery block is actually a
high-speed shifter operating at x16 times the baud rate,
whereas the main receive serial shifter operates at the
bit rate or at FOSC. This mode would typically be used
in RS-232 systems.
This mode would typically be used in RS-485 systems.
To set up an Asynchronous Reception with Address
Detect Enable:
1.
Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
2. Enable the asynchronous serial port by clearing
the SYNC bit and setting the SPEN bit.
3. If interrupts are required, set the RCEN bit and
select the desired priority level with the RCIP bit.
4. Set the RX9 bit to enable 9-bit reception.
5. Set the ADDEN bit to enable address detect.
6. Enable reception by setting the CREN bit.
7. The RCIF bit will be set when reception is
complete. The interrupt will be Acknowledged if
the RCIE and GIE bits are set.
8. Read the RCSTA register to determine if any
error occurred during reception, as well as read
bit 9 of data (if applicable).
9. Read RCREG to determine if the device is being
addressed.
10. If any error occurred, clear the CREN bit.
11. If the device has been addressed, clear the
ADDEN bit to allow all received data into the
receive buffer and interrupt the CPU.
To set up an Asynchronous Reception:
1.
Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
2. Enable the asynchronous serial port by clearing
bit, SYNC, and setting bit, SPEN.
3. If interrupts are desired, set enable bit, RCIE.
4. If 9-bit reception is desired, set bit, RX9.
5. Enable the reception by setting bit, CREN.
6. Flag bit, RCIF, will be set when reception is
complete and an interrupt will be generated if
enable bit, RCIE, was set.
7. Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
8. Read the 8-bit received data by reading the
RCREG register.
9. If any error occurred, clear the error by clearing
enable bit, CREN.
10. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
FIGURE 18-6:
SETTING UP 9-BIT MODE WITH
ADDRESS DETECT
EUSART RECEIVE BLOCK DIAGRAM
CREN
OERR
FERR
x64 Baud Rate CLK
BRG16
SPBRGH
SPBRG
Baud Rate Generator
÷ 64
or
÷ 16
or
÷4
RSR Register
MSb
Stop
(8)
7
• • •
1
LSb
0
Start
RX9
Pin Buffer
and Control
Data
Recovery
RX
RX9D
RCREG Register
FIFO
SPEN
8
Interrupt
RCIF
Data Bus
RCIE
© 2008 Microchip Technology Inc.
DS39631E-page 213
PIC18F2420/2520/4420/4520
FIGURE 18-7:
ASYNCHRONOUS RECEPTION
Start
bit
RX (pin)
bit 0
bit 7/8 Stop
bit
bit 1
Rcv Shift Reg
Rcv Buffer Reg
Start
bit
bit 0
bit 7/8
Start
bit
bit 7/8
Stop
bit
Word 2
RCREG
Word 1
RCREG
Read Rcv
Buffer Reg
RCREG
Stop
bit
RCIF
(Interrupt Flag)
OERR bit
CREN
Note:
This timing diagram shows three words appearing on the RX input.
causing the OERR (overrun) bit to be set.
TABLE 18-6:
Name
The RCREG (receive buffer) is read after the third word
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Bit 7
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
Bit 6
INTCON
GIE/GIEH PEIE/GIEL
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
51
RCSTA
RCREG
EUSART Receive Register
51
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
BAUDCON
ABDOVF
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
SPBRGH
EUSART Baud Rate Generator Register High Byte
51
SPBRG
EUSART Baud Rate Generator Register Low Byte
51
TXSTA
51
51
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
18.2.4
AUTO-WAKE-UP ON SYNC BREAK
CHARACTER
During Sleep mode, all clocks to the EUSART are
suspended. Because of this, the Baud Rate Generator
is inactive and a proper byte reception cannot be performed. The auto-wake-up feature allows the controller
to wake-up due to activity on the RX/DT line while the
EUSART is operating in Asynchronous mode.
The auto-wake-up feature is enabled by setting the
WUE bit (BAUDCON<1>). Once set, the typical 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.)
DS39631E-page 214
Following a wake-up event, the module generates an
RCIF interrupt. The interrupt is generated synchronously to the Q clocks in normal operating modes
(Figure 18-8) and asynchronously, if the device is in
Sleep mode (Figure 18-9). The interrupt condition is
cleared by reading the RCREG register.
The WUE bit is automatically cleared once a low-tohigh transition is observed on the RX line following the
wake-up event. At this point, the EUSART module is in
Idle mode and returns to normal operation. This signals
to the user that the Sync Break event is over.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.2.4.1
Special Considerations Using
Auto-Wake-up
18.2.4.2
Since auto-wake-up functions by sensing rising edge
transitions on RX/DT, information with any state
changes before the Stop bit may signal a false End-ofCharacter (EOC) and cause data or framing errors. To
work properly, therefore, the initial character in the
transmission must be all ‘0’s. This can be 00h (8 bytes)
for standard RS-232 devices or 000h (12 bits) for LIN
bus.
The timing of WUE and RCIF events may cause some
confusion when it comes to determining the validity of
received data. As noted, setting the WUE bit places the
EUSART in an Idle mode. The wake-up event causes a
receive interrupt by setting the RCIF bit. The WUE bit is
cleared after this when a rising edge is seen on RX/DT.
The interrupt condition is then cleared by reading the
RCREG register. Ordinarily, the data in RCREG will be
dummy data and should be discarded.
Oscillator start-up time must also be considered,
especially in applications using oscillators with longer
start-up intervals (i.e., XT or HS 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.
FIGURE 18-8:
Special Considerations Using
the WUE Bit
The fact that the WUE bit has been cleared (or is still
set) and the RCIF flag is set should not be used as an
indicator of the integrity of the data in RCREG. Users
should consider implementing a parallel method in
firmware to verify received data integrity.
To assure that no actual data is lost, check the RCIDL
bit to verify that a receive operation is not in process. If
a receive operation is not occurring, the WUE bit may
then be set just prior to entering the Sleep mode.
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING NORMAL OPERATION
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 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
OSC1
Bit Set by User
Auto-Cleared
WUE bit(1)
RX/DT Line
RCIF
Cleared Due to User Read of RCREG
Note 1: The EUSART remains in Idle while the WUE bit is set.
FIGURE 18-9:
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
OSC1
Q1
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Bit Set by User
Auto-Cleared
WUE bit(2)
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 auto-clear of the WUE bit can occur before the oscillator is ready. This
sequence should not depend on the presence of Q clocks.
The EUSART remains in Idle while the WUE bit is set.
© 2008 Microchip Technology Inc.
DS39631E-page 215
PIC18F2420/2520/4420/4520
18.2.5
BREAK CHARACTER SEQUENCE
The EUSART module has the capability of sending the
special Break character sequences that are required by
the LIN bus standard. The Break character transmit
consists of a Start bit, followed by twelve ‘0’ bits and a
Stop bit. The frame Break character is sent whenever
the SENDB and TXEN bits (TXSTA<3> and
TXSTA<5>) are set while the Transmit Shift register is
loaded with data. Note that 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).
Note that the data value written to the TXREG for the
Break character is ignored. The write simply serves the
purpose of initiating the proper sequence.
The TRMT bit indicates when the transmit operation is
active or Idle, just as it does during normal transmission. See Figure 18-10 for the timing of the Break
character sequence.
18.2.5.1
Break and Sync Transmit Sequence
The following sequence will send 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.
FIGURE 18-10:
Write to TXREG
1.
2.
3.
4.
5.
Configure the EUSART for the desired mode.
Set the TXEN and SENDB bits to set up the
Break character.
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. The Sync character now
transmits in the preconfigured mode.
When the TXREG becomes empty, as indicated by the
TXIF, the next data byte can be written to TXREG.
18.2.6
RECEIVING A BREAK CHARACTER
The Enhanced USART module can receive a Break
character in two ways.
The first method forces configuration of the baud rate
at a frequency of 9/13 the typical speed. This allows for
the Stop bit transition to be at the correct sampling location (13 bits for Break versus Start bit and 8 data bits for
typical data).
The second method uses the auto-wake-up feature
described in Section 18.2.4 “Auto-Wake-up on Sync
Break Character”. 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 Rate Detect
feature. For both methods, the user can set the ABD bit
once the TXIF interrupt is observed.
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 Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
SENDB Sampled Here
Auto-Cleared
SENDB
(Transmit Shift
Reg. Empty Flag)
DS39631E-page 216
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.3
Once the TXREG register transfers the data to the TSR
register (occurs in one TCY), the TXREG is empty and
the TXIF flag bit (PIR1<4>) is set. The interrupt can be
enabled or disabled by setting or clearing the interrupt
enable bit, TXIE (PIE1<4>). TXIF is set regardless of
the state of enable bit, TXIE; it cannot be cleared in
software. It will reset only when new data is loaded into
the TXREG register.
EUSART Synchronous
Master Mode
The Synchronous Master mode is entered by setting
the CSRC bit (TXSTA<7>). In this mode, the data is
transmitted in a half-duplex manner (i.e., transmission
and reception do not occur at the same time). When
transmitting data, the reception is inhibited and vice
versa. Synchronous mode is entered by setting bit,
SYNC (TXSTA<4>). In addition, enable bit, SPEN
(RCSTA<7>), is set in order to configure the TX and RX
pins to CK (clock) and DT (data) lines, respectively.
While flag bit, TXIF, indicates the status of the TXREG
register, another bit, TRMT (TXSTA<1>), shows the
status of the TSR register. TRMT is a read-only bit which
is set when the TSR is empty. No interrupt logic is tied to
this bit so the user has to poll this bit in order to determine if the TSR register is empty. The TSR is not
mapped in data memory so it is not available to the user.
The Master mode indicates that the processor transmits the master clock on the CK line. Clock polarity is
selected with the TXCKP bit (BAUDCON<4>); setting
TXCKP sets the Idle state on CK as high, while clearing
the bit sets the Idle state as low. This option is provided
to support Microwire devices with this module.
18.3.1
To set up a Synchronous Master Transmission:
1.
EUSART SYNCHRONOUS MASTER
TRANSMISSION
2.
The EUSART transmitter block diagram is shown in
Figure 18-3. The heart of the transmitter is the Transmit
(Serial) Shift Register (TSR). The Shift register obtains
its data from the Read/Write Transmit Buffer register,
TXREG. The TXREG register is loaded with data in
software. The TSR register is not loaded until the last
bit has been transmitted from the previous load. As
soon as the last bit is transmitted, the TSR is loaded
with new data from the TXREG (if available).
FIGURE 18-11:
3.
4.
5.
6.
7.
8.
Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRG16
bit, as required, to achieve the desired baud rate.
Enable the synchronous master serial port by
setting bits, SYNC, SPEN and CSRC.
If interrupts are desired, set enable bit, TXIE.
If 9-bit transmission is desired, set bit, TX9.
Enable the transmission by setting bit, TXEN.
If 9-bit transmission is selected, the ninth bit
should be loaded in bit, TX9D.
Start transmission by loading data to the TXREG
register.
If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
SYNCHRONOUS TRANSMISSION
Q1 Q2 Q3Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4
RC7/RX/DT
bit 0
bit 1
bit 2
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
bit 7
Word 1
bit 0
bit 1
bit 7
Word 2
RC6/TX/CK pin
(TXCKP = 0)
RC6/TX/CK pin
(TXCKP = 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.
© 2008 Microchip Technology Inc.
DS39631E-page 217
PIC18F2420/2520/4420/4520
FIGURE 18-12:
SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
RC7/RX/DT pin
bit 0
bit 1
bit 2
bit 6
bit 7
RC6/TX/CK pin
Write to
TXREG reg
TXIF bit
TRMT bit
TXEN bit
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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
51
RCSTA
TXREG
EUSART Transmit Register
51
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
51
BAUDCON
ABDOVF
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
51
SPBRGH
EUSART Baud Rate Generator Register High Byte
51
SPBRG
EUSART Baud Rate Generator Register Low Byte
51
TXSTA
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
DS39631E-page 218
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.3.2
EUSART SYNCHRONOUS
MASTER RECEPTION
3.
4.
5.
6.
Ensure bits, CREN and SREN, are clear.
If interrupts are desired, set enable bit, RCIE.
If 9-bit reception is desired, set bit, RX9.
If a single reception is required, set bit, SREN.
For continuous reception, set bit, CREN.
7. Interrupt flag bit, RCIF, will be set when reception
is complete and an interrupt will be generated if
the enable bit, RCIE, was set.
8. Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
9. Read the 8-bit received data by reading the
RCREG register.
10. If any error occurred, clear the error by clearing
bit, CREN.
11. If using interrupts, ensure that the GIE and PEIE bits
in the INTCON register (INTCON<7:6>) are set.
Once Synchronous mode is selected, reception is
enabled by setting either the Single Receive Enable bit,
SREN (RCSTA<5>), or the Continuous Receive
Enable bit, CREN (RCSTA<4>). Data is sampled on the
RX pin on the falling edge of the clock.
If enable bit, SREN, is set, only a single word is
received. If enable bit, CREN, is set, the reception is
continuous until CREN is cleared. If both bits are set,
then CREN takes precedence.
To set up a Synchronous Master Reception:
1.
2.
Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRG16
bit, as required, to achieve the desired baud rate.
Enable the synchronous master serial port by
setting bits, SYNC, SPEN and CSRC.
FIGURE 18-13:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
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 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
RC7/RX/DT
pin
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
RC6/TX/CK pin
(TXCKP = 0)
RC6/TX/CK pin
(TXCKP = 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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
RCSTA
RCREG
TXSTA
EUSART Receive Register
CSRC
BAUDCON ABDOVF
51
51
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
51
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
51
SPBRGH
EUSART Baud Rate Generator Register High Byte
51
SPBRG
EUSART Baud Rate Generator Register Low Byte
51
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.
© 2008 Microchip Technology Inc.
DS39631E-page 219
PIC18F2420/2520/4420/4520
18.4
To set up a Synchronous Slave Transmission:
EUSART Synchronous
Slave Mode
1.
Synchronous Slave mode is entered by clearing bit,
CSRC (TXSTA<7>). This mode differs from the
Synchronous Master mode in that the shift clock is supplied externally at the CK pin (instead of being supplied
internally in Master mode). This allows the device to
transfer or receive data while in any low-power mode.
18.4.1
EUSART SYNCHRONOUS
SLAVE TRANSMISSION
2.
3.
4.
5.
6.
The operation of the Synchronous Master and Slave
modes is identical, except in the case of the Sleep
mode.
7.
8.
If two words are written to the TXREG and then the
SLEEP instruction is executed, the following will occur:
a)
b)
c)
d)
e)
Enable the synchronous slave serial port by
setting bits, SYNC and SPEN, and clearing bit,
CSRC.
Clear bits, CREN and SREN.
If interrupts are desired, set enable bit, TXIE.
If 9-bit transmission is desired, set bit, TX9.
Enable the transmission by setting enable bit,
TXEN.
If 9-bit transmission is selected, the ninth bit
should be loaded in bit, TX9D.
Start transmission by loading data to the TXREG
register.
If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
The first word will immediately transfer to the
TSR register and transmit.
The second word will remain in the TXREG
register.
Flag bit, TXIF, will not be set.
When the first word has been shifted out of TSR,
the TXREG register will transfer the second
word to the TSR and flag bit, TXIF, will now be
set.
If enable bit, TXIE, is set, the interrupt will wake
the chip from Sleep. If the global interrupt is
enabled, the program will branch to the interrupt
vector.
TABLE 18-9:
Name
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
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
INTCON
GIE/GIEH PEIE/GIEL TMR0IE
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
51
RCSTA
TXREG
TXSTA
EUSART Transmit Register
51
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
51
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
51
BAUDCON
ABDOVF
SPBRGH
EUSART Baud Rate Generator Register High Byte
51
SPBRG
EUSART Baud Rate Generator Register Low Byte
51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave transmission.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
DS39631E-page 220
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.4.2
EUSART SYNCHRONOUS SLAVE
RECEPTION
To set up a Synchronous Slave Reception:
1.
The operation of the Synchronous Master and Slave
modes is identical, except in the case of Sleep, or any
Idle mode and bit, SREN, which is a “don’t care” in
Slave mode.
If receive is enabled by setting the CREN bit prior to
entering Sleep or any Idle mode, then a word may be
received while in this low-power mode. 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 chip from the low-power
mode. If the global interrupt is enabled, the program will
branch to the interrupt vector.
2.
3.
4.
5.
6.
7.
8.
9.
Enable the synchronous master serial port by
setting bits, SYNC and SPEN, and clearing bit,
CSRC.
If interrupts are desired, set enable bit, RCIE.
If 9-bit reception is desired, set bit, RX9.
To enable reception, set enable bit, CREN.
Flag bit, RCIF, will be set when reception is
complete. An interrupt will be generated if
enable bit, RCIE, was set.
Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
Read the 8-bit received data by reading the
RCREG register.
If any error occurred, clear the error by clearing
bit, CREN.
If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
51
RCSTA
RCREG
TXSTA
EUSART Receive Register
51
CSRC
TX9
TXEN
SYNC
SENDB
BRGH
TRMT
TX9D
51
BAUDCON
ABDOVF
RCIDL
RXDTP
TXCKP
BRG16
—
WUE
ABDEN
51
SPBRGH
EUSART Baud Rate Generator Register High Byte
51
SPBRG
EUSART Baud Rate Generator Register Low Byte
51
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.
© 2008 Microchip Technology Inc.
DS39631E-page 221
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 222
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
19.0
10-BIT ANALOG-TO-DIGITAL
CONVERTER (A/D) MODULE
The Analog-to-Digital (A/D) Converter module has
10 inputs for the 28-pin devices and 13 for the 40/44-pin
devices. This module allows conversion of an analog
input signal to a corresponding 10-bit digital number.
The ADCON0 register, shown in Register 19-1,
controls the operation of the A/D module. The
ADCON1 register, shown in Register 19-2, configures
the functions of the port pins. The ADCON2 register,
shown in Register 19-3, configures the A/D clock
source, programmed acquisition time and justification.
The module has five registers:
•
•
•
•
•
A/D Result High Register (ADRESH)
A/D Result Low Register (ADRESL)
A/D Control Register 0 (ADCON0)
A/D Control Register 1 (ADCON1)
A/D Control Register 2 (ADCON2)
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
bit 7-6
Unimplemented: Read as ‘0’
bit 5-2
CHS<3:0>: Analog Channel Select bits
0000 = Channel 0 (AN0)
0001 = Channel 1 (AN1)
0010 = Channel 2 (AN2)
0011 = Channel 3 (AN3)
0100 = Channel 4 (AN4)
0101 = Channel 5 (AN5)(1,2)
0110 = Channel 6 (AN6)(1,2)
0111 = Channel 7 (AN7)(1,2)
1000 = Channel 8 (AN8)
1001 = Channel 9 (AN9)
1010 = Channel 10 (AN10)
1011 = Channel 11 (AN11)
1100 = Channel 12 (AN12)
1101 = Unimplemented)(2)
1110 = Unimplemented)(2)
1111 = Unimplemented)(2)
bit 1
GO/DONE: A/D Conversion Status bit
When ADON = 1:
1 = A/D conversion in progress
0 = A/D Idle
bit 0
ADON: A/D On bit
1 = A/D Converter module is enabled
0 = A/D Converter module is disabled
Note 1:
2:
x = Bit is unknown
These channels are not implemented on 28-pin devices.
Performing a conversion on unimplemented channels will return a floating input measurement.
© 2008 Microchip Technology Inc.
DS39631E-page 223
PIC18F2420/2520/4420/4520
REGISTER 19-2:
ADCON1: A/D CONTROL REGISTER 1
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-q(1)
R/W-q(1)
R/W-q(1)
—
—
VCFG1
VCFG0
PCFG3
PCFG2
PCFG1
PCFG0
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
PCFG3:
PCFG0
AN6(2)
AN5(2)
AN4
AN3
AN2
AN1
AN0
PCFG<3:0>: A/D Port Configuration Control bits:
AN7(2)
bit 3-0
AN8
VCFG0: Voltage Reference Configuration bit (VREF+ source)
1 = VREF+ (AN3)
0 = VDD
AN9
bit 4
AN10
VCFG1: Voltage Reference Configuration bit (VREF- source)
1 = VREF- (AN2)
0 = VSS
AN11
Unimplemented: Read as ‘0’
bit 5
AN12
bit 7-6
0000(1)
0001
0010
0011
0100
0101
0110
A
A
A
D
D
D
D
D
A
A
A
A
D
D
D
D
A
A
A
A
A
D
D
D
A
A
A
A
A
A
D
D
A
A
A
A
A
A
A
D
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
A
D
D
D
D
D
D
D
A
A
D
D
D
D
D
D
A
A
A
D
D
D
D
D
A
A
A
A
D
D
D
D
A
A
A
A
A
D
D
D
A
A
A
A
A
A
D
D
A
A
A
A
A
A
A
D
0111(1)
1000
1001
1010
1011
1100
1101
1110
1111
A = Analog input
Note 1:
2:
x = Bit is unknown
D = Digital I/O
The POR value of the PCFG bits depends on the value of the PBADEN Configuration bit. When
PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111.
AN5 through AN7 are available only on 40/44-pin devices.
DS39631E-page 224
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
ADFM: A/D 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
111 = 20 TAD
110 = 16 TAD
101 = 12 TAD
100 = 8 TAD
011 = 6 TAD
010 = 4 TAD
001 = 2 TAD
000 = 0 TAD(1)
bit 2-0
ADCS<2:0>: A/D Conversion Clock Select bits
111 = FRC (clock derived from A/D RC oscillator)(1)
110 = FOSC/64
101 = FOSC/16
100 = FOSC/4
011 = FRC (clock derived from A/D RC oscillator)(1)
010 = FOSC/32
001 = FOSC/8
000 = FOSC/2
Note 1:
x = Bit is unknown
If the A/D FRC clock source is selected, a delay of one TCY (instruction cycle) is added before the A/D
clock starts. This allows the SLEEP instruction to be executed before starting a conversion.
© 2008 Microchip Technology Inc.
DS39631E-page 225
PIC18F2420/2520/4420/4520
The analog reference voltage is software selectable to
either the device’s positive and negative supply voltage
(VDD and VSS), or the voltage level on the RA3/AN3/
VREF+ and RA2/AN2/VREF-/CVREF pins.
A device Reset forces all registers to their Reset state.
This forces the A/D module to be turned off and any
conversion in progress is aborted.
Each port pin associated with the A/D Converter can be
configured as an analog input, or as a digital I/O. The
ADRESH and ADRESL registers contain the result of the
A/D conversion. When the A/D conversion is complete,
the result is loaded into the ADRESH:ADRESL register
pair, the GO/DONE bit (ADCON0 register) is cleared and
the A/D Interrupt Flag bit, ADIF, is set. The block diagram
of the A/D module is shown in Figure 19-1.
The A/D Converter has a unique feature of being able
to operate while the device is in Sleep mode. To operate in Sleep, the A/D conversion clock must be derived
from the A/D’s internal RC oscillator.
The output of the sample and hold is the input into the
converter, which generates the result via successive
approximation.
FIGURE 19-1:
A/D BLOCK DIAGRAM
CHS<3:0>
1100
1011
1010
1001
(Input Voltage)
Reference
Voltage
VREF+
VREF-
AN9
AN8
AN7(1)
0110
AN6(1)
0101
AN5(1)
0100
AN4
0011
AN3
0001
VDD(2)
AN10
0111
0010
VCFG<1:0>
AN11
1000
VAIN
10-Bit
A/D
Converter
AN12
0000
AN2
AN1
AN0
X0
X1
1X
0X
VSS(2)
Note 1:
2:
Channels, AN5 through AN7, are not available on 28-pin devices.
I/O pins have diode protection to VDD and VSS.
DS39631E-page 226
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Wait for A/D conversion to complete, by either:
• Polling for the GO/DONE bit to be cleared
OR
• Waiting for the A/D interrupt
Read A/D Result registers (ADRESH:ADRESL);
clear bit, ADIF, if required.
For next conversion, go to step 1 or step 2, as
required. The A/D conversion time per bit is
defined as TAD. A minimum wait of 2 TAD is
required before the next acquisition starts.
6.
7.
FIGURE 19-2:
3FFh
1.
3FEh
FIGURE 19-3:
002h
001h
1023 LSB
1023.5 LSB
1022 LSB
1022.5 LSB
3 LSB
Analog Input Voltage
ANALOG INPUT MODEL
VDD
Rs
VAIN
2 LSB
000h
2.5 LSB
3.
4.
A/D TRANSFER FUNCTION
003h
0.5 LSB
2.
Configure the A/D module:
• Configure analog pins, voltage reference and
digital I/O (ADCON1)
• Select A/D input channel (ADCON0)
• Select A/D acquisition time (ADCON2)
• Select A/D conversion clock (ADCON2)
• Turn on A/D module (ADCON0)
Configure A/D interrupt (if desired):
• Clear ADIF bit
• Set ADIE bit
• Set GIE bit
Wait the required acquisition time (if required).
Start conversion:
• Set GO/DONE bit (ADCON0 register)
Digital Code Output
The following steps should be followed to perform an A/D
conversion:
1 LSB
After the A/D module has been configured as desired,
the selected channel must be acquired before the
conversion is started. The analog input channels must
have their corresponding TRIS bits selected as an
input. To determine acquisition time, see Section 19.1
“A/D Acquisition Requirements”. After this acquisition time has elapsed, the A/D conversion can be
started. An acquisition time can be programmed to
occur between setting the GO/DONE bit and the actual
start of the conversion.
5.
1.5 LSB
The value in the ADRESH:ADRESL registers is not
modified for a Power-on Reset. The ADRESH:ADRESL
registers will contain unknown data after a Power-on
Reset.
ANx
VT = 0.6V
RIC ≤ 1k
CPIN
5 pF
Sampling
Switch
VT = 0.6V
SS
RSS
ILEAKAGE
±100 nA
CHOLD = 25 pF
VSS
Legend: CPIN
= Input Capacitance
VT
= Threshold Voltage
ILEAKAGE = Leakage Current at the pin due to
various junctions
= Interconnect Resistance
RIC
= Sampling Switch
SS
= Sample/Hold Capacitance (from DAC)
CHOLD
RSS
= Sampling Switch Resistance
© 2008 Microchip Technology Inc.
VDD
6V
5V
4V
3V
2V
1
2
3
4
Sampling Switch (kΩ)
DS39631E-page 227
PIC18F2420/2520/4420/4520
19.1
A/D Acquisition Requirements
For the A/D Converter 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 19-3. 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). The source impedance affects the offset voltage
at the analog input (due to pin leakage current). The
maximum recommended impedance for analog
sources is 2.5 kΩ. After the analog input channel is
selected (changed), the channel must be sampled for
at least the minimum acquisition time before starting a
conversion.
EQUATION 19-1:
CHOLD
Rs
Conversion Error
VDD
Temperature
=
=
≤
=
=
25 pF
2.5 kΩ
1/2 LSb
5V → Rss = 2 kΩ
85°C (system max.)
ACQUISITION TIME
=
Amplifier Settling Time + Holding Capacitor Charging Time + Temperature Coefficient
=
TAMP + TC + TCOFF
EQUATION 19-2:
VHOLD
or
TC
Example 19-3 shows the calculation of the minimum
required acquisition time TACQ. This calculation is
based on the following application system
assumptions:
When the conversion is started, the
holding capacitor is disconnected from the
input pin.
Note:
TACQ
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 A/D). The
1/2 LSb error is the maximum error allowed for the A/D
to meet its specified resolution.
A/D MINIMUM CHARGING TIME
=
(VREF – (VREF/2048)) • (1 – e(-TC/CHOLD(RIC + RSS + RS)))
=
-(CHOLD)(RIC + RSS + RS) ln(1/2048)
EQUATION 19-3:
CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME
TACQ
=
TAMP + TC + TCOFF
TAMP
=
0.2 μs
TCOFF
=
(Temp – 25°C)(0.02 μs/°C)
(85°C – 25°C)(0.02 μs/°C)
1.2 μs
Temperature coefficient is only required for temperatures > 25°C. Below 25°C, TCOFF = 0 μs.
TC
=
-(CHOLD)(RIC + RSS + RS) ln(1/2047) μs
-(25 pF) (1 kΩ + 2 kΩ + 2.5 kΩ) ln(0.0004883) μs
1.05 μs
TACQ
=
0.2 μs + 1 μs + 1.2 μs
2.4 μs
DS39631E-page 228
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
19.2
Selecting and Configuring
Acquisition Time
19.3
Selecting the A/D Conversion
Clock
The ADCON2 register allows the user to select an
acquisition time that occurs each time the GO/DONE
bit is set. It also gives users the option to use an
automatically determined acquisition time.
The A/D conversion time per bit is defined as TAD. The
A/D conversion requires 11 TAD per 10-bit conversion.
The source of the A/D conversion clock is software
selectable. There are seven possible options for TAD:
Acquisition time may be set with the ACQT<2:0> bits
(ADCON2<5:3>), which provides 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 may
be 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.
For correct A/D conversions, the A/D conversion clock
(TAD) must be as short as possible, but greater than the
minimum TAD (see parameter 130 for more
information).
2 TOSC
4 TOSC
8 TOSC
16 TOSC
32 TOSC
64 TOSC
Internal RC Oscillator
Table 19-1 shows the resultant TAD times derived from
the device operating frequencies and the A/D clock
source selected.
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. If an acquisition time is programmed, there is
nothing to indicate if the acquisition time has ended or
if the conversion has begun.
TABLE 19-1:
TAD vs. DEVICE OPERATING FREQUENCIES
AD Clock Source (TAD)
Operation
ADCS<2:0>
PIC18F2X20/4X20
PIC18LF2X2X/4X20(4)
2 TOSC
000
2.86 MHz
1.43 kHz
4 TOSC
100
5.71 MHz
2.86 MHz
8 TOSC
001
11.43 MHz
5.72 MHz
16 TOSC
101
22.86 MHz
11.43 MHz
32 TOSC
010
40.0 MHz
22.86 MHz
64 TOSC
110
40.0 MHz
22.86 MHz
RC(3)
Note 1:
2:
3:
4:
Maximum Device Frequency
x11
1.00
MHz(1)
1.00 MHz(2)
The RC source has a typical TAD time of 1.2 μs.
The RC source has a typical TAD time of 2.5 μs.
For device frequencies above 1 MHz, the device must be in Sleep for the entire conversion or the A/D
accuracy may be out of specification.
Low-power (PIC18LFXXXX) devices only.
© 2008 Microchip Technology Inc.
DS39631E-page 229
PIC18F2420/2520/4420/4520
19.4
Operation in Power-Managed
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 RC
clock source should be selected.
Operation in Sleep mode requires the A/D FRC clock to
be selected. If the ACQT<2:0> bits are set to ‘000’ and
a conversion is started, the conversion will be delayed
one instruction cycle to allow execution of the SLEEP
instruction and entry to Sleep mode. The IDLEN bit
(OSCCON<7>) must have already been cleared prior
to starting the conversion.
DS39631E-page 230
19.5
Configuring Analog Port Pins
The ADCON1, TRISA, TRISB and TRISE registers all
configure the A/D port pins. The port pins needed as
analog inputs must have their corresponding TRIS bits
set (input). If the TRIS bit is cleared (output), the digital
output level (VOH or VOL) will be converted.
The A/D operation is independent of the state of the
CHS<3:0> bits and the TRIS bits.
Note 1: When reading the PORT register, all pins
configured as analog input channels will
read as cleared (a low level). Pins configured as digital inputs will convert as
analog inputs. Analog levels on a digitally
configured input will be accurately
converted.
2: Analog levels on any pin defined as a digital input may cause the digital input buffer
to consume current out of the device’s
specification limits.
3: The PBADEN bit, in Configuration
Register 3H, configures PORTB pins to
reset as analog or digital pins by controlling how the PCFG bits in ADCON1 are
reset.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
19.6
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, acquisition on the selected
channel is automatically started.
A/D Conversions
Figure 19-4 shows the operation of the A/D Converter
after the GO/DONE 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.
Figure 19-5 shows the operation of the A/D Converter
after the GO/DONE bit has been set and the
ACQT<2:0> bits are set to ‘010’, and selecting a 4 TAD
acquisition time before the conversion starts.
19.7
Discharge
The discharge phase is used to initialize the value of
the capacitor array. The array is discharged before
every sample. This feature helps to optimize the unitygain amplifier, as the circuit always needs to charge the
capacitor array, rather than charge/discharge based on
previous measure values.
Clearing the GO/DONE bit during a conversion will abort
the current conversion. The A/D Result register pair will
NOT be updated with the partially completed A/D
conversion sample. This means the ADRESH:ADRESL
registers will continue to contain the value of the last
completed conversion (or the last value written to the
ADRESH:ADRESL registers).
FIGURE 19-4:
The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
Note:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)
TCY - TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11 TAD1
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/DONE bit
On the following cycle:
ADRESH:ADRESL are loaded, GO/DONE bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
FIGURE 19-5:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)
TAD Cycles
TACQT Cycles
1
2
3
Automatic
Acquisition
Time
4
1
2
3
4
5
6
7
8
9
10
11
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0
Conversion starts
(Holding capacitor is disconnected)
Set GO/DONE bit
(Holding capacitor continues
acquiring input)
© 2008 Microchip Technology Inc.
TAD1
Discharge
On the following cycle:
ADRESH:ADRESL are loaded, GO/DONE bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
DS39631E-page 231
PIC18F2420/2520/4420/4520
19.8
Use of the CCP2 Trigger
An A/D conversion can be started by the Special Event
Trigger of the CCP2 module. This requires that the
CCP2M<3:0> bits (CCP2CON<3:0>) be programmed
as ‘1011’ and that the A/D module is enabled (ADON
bit is set). When the trigger occurs, the GO/DONE bit
will be set, starting the A/D acquisition and conversion,
and the Timer1 (or Timer3) counter will be reset to zero.
Timer1 (or Timer3) is reset to automatically repeat the
A/D acquisition period with minimal software overhead
(moving ADRESH:ADRESL to the desired location).
TABLE 19-2:
Name
The appropriate analog input channel must be selected
and the minimum acquisition period is either timed by
the user, or an appropriate TACQ time is selected before
the Special Event Trigger sets the GO/DONE bit (starts
a conversion).
If the A/D module is not enabled (ADON is cleared), the
Special Event Trigger will be ignored by the A/D
module, but will still reset the Timer1 (or Timer3)
counter.
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
49
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
52
PIE1
(1)
PSPIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
52
IPR1
PSPIP(1)
ADIP
RCIP
TXIP
SSPIP
CCP1IP
TMR2IP
TMR1IP
52
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
IPR2
ADRESH
A/D Result Register High Byte
ADRESL
A/D Result Register Low Byte
ADCON0
51
51
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
51
ADCON1
—
—
VCFG1
VCFG0
PCFG3
PCFG2
PCFG1
PCFG0
51
ADCON2
ADFM
—
ACQT2
ACQT1
ACQT0
ADCS2
ADCS1
ADCS0
51
PORTA
RA7(2)
RA6(2)
RA5
RA4
RA3
RA2
RA1
RA0
52
TRISA
TRISA7(2)
TRISA6(2)
PORTB
RB7
RB6
RB2
RB1
RB0
52
PORTA Data Direction Register
RB5
RB4
RB3
TRISB
PORTB Data Direction Register
LATB
PORTB Data Latch Register (Read and Write to Data Latch)
52
52
52
PORTE(4)
—
—
—
—
RE3(3)
RE2
RE1
RE0
52
TRISE(4)
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
52
LATE(4)
—
—
—
—
—
PORTE Data Latch Register
52
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for A/D conversion.
Note 1: These bits are unimplemented on 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’.
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 28-pin devices.
DS39631E-page 232
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
20.0
COMPARATOR MODULE
The analog comparator module contains two
comparators that can be configured in a variety of
ways. The inputs can be selected from the analog
inputs multiplexed with pins, RA0 through RA5, as well
as the on-chip voltage reference (see Section 21.0
“Comparator Voltage Reference Module”). The digital outputs (normal or inverted) are available at the pin
level and can also be read through the control register.
REGISTER 20-1:
R-0
C2OUT
bit 7
The CMCON register (Register 20-1) selects the
comparator input and output configuration. Block
diagrams of the various comparator configurations are
shown in Figure 20-1.
CMCON: COMPARATOR CONTROL REGISTER
R-0
R/W-0
R/W-0
R/W-0
R/W-1
R/W-1
C1OUT
C2INV
C1INV
CIS
CM2
CM1
R/W-1
CM0
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
bit 7
C2OUT: Comparator 2 Output bit
When C2INV = 0:
1 = C2 VIN+ > C2 VIN0 = C2 VIN+ < C2 VINWhen C2INV = 1:
1 = C2 VIN+ < C2 VIN0 = C2 VIN+ > C2 VIN-
bit 6
C1OUT: Comparator 1 Output bit
When C1INV = 0:
1 = C1 VIN+ > C1 VIN0 = C1 VIN+ < C1 VINWhen C1INV = 1:
1 = C1 VIN+ < C1 VIN0 = C1 VIN+ > C1 VIN-
bit 5
C2INV: Comparator 2 Output Inversion bit
1 = C2 output inverted
0 = C2 output not inverted
C1INV: Comparator 1 Output Inversion bit
1 = C1 output inverted
0 = C1 output not inverted
bit 4
bit 3
bit 2-0
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
CIS: Comparator Input Switch bit
When CM<2:0> = 110:
1 = C1 VIN- connects to RA3/AN3/VREF+
C2 VIN- connects to RA2/AN2/VREF-/CVREF
0 = C1 VIN- connects to RA0/AN0
C2 VIN- connects to RA1/AN1
CM<2:0>: Comparator Mode bits
Figure 20-1 shows the Comparator modes and the CM<2:0> bit settings.
© 2008 Microchip Technology Inc.
DS39631E-page 233
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20.1
Comparator Configuration
There are eight modes of operation for the comparators, shown in Figure 20-1. Bits CM<2:0> of the
CMCON register are used to select these modes. The
TRISA register controls the data direction of the comparator pins for each mode. If the Comparator mode is
FIGURE 20-1:
Comparators Off (POR Default Value)
CM<2:0> = 111
A
VIN-
RA3/AN3/ A
VREF+
VIN+
A
VIN-
RA1/AN1
RA2/AN2/ A
VREF-/CVREF
VIN+
C1
Off (Read as ‘0’)
C2
Off (Read as ‘0’)
Two Independent Comparators
CM<2:0> = 010
A
VIN-
RA3/AN3/ A
VREF+
VIN+
A
VIN-
RA2/AN2/ A
VREF-/CVREF
VIN+
RA0/AN0
Comparator interrupts should be disabled
during a Comparator mode change;
otherwise, a false interrupt may occur.
Note:
COMPARATOR I/O OPERATING MODES
Comparators Reset
CM<2:0> = 000
RA0/AN0
changed, the comparator output level may not be valid
for the specified mode change delay shown in
Section 26.0 “Electrical Characteristics”.
C1
RA0/AN0
D
VIN-
RA3/AN3/
VREF+
D
VIN+
RA1/AN1
D
VIN-
D
RA2/AN2/
VREF-/CVREF
VIN+
C1
Off (Read as ‘0’)
C2
Off (Read as ‘0’)
Two Independent Comparators with Outputs
CM<2:0> = 011
C1OUT
RA0/AN0
RA3/AN3/
VREF+
A
VIN-
A
VIN+
C1
C1OUT
C2
C2OUT
RA4/T0CKI/C1OUT*
RA1/AN1
C2
C2OUT
A
VIN-
RA2/AN2/ A
VREF-/CVREF
VIN+
RA1/AN1
RA5/AN4/SS/HLVDIN/C2OUT*
Two Common Reference Comparators
CM<2:0> = 100
A
VIN-
RA3/AN3/ A
VREF+
VIN+
A
VIN-
RA2/AN2/ D
VREF-/CVREF
VIN+
RA0/AN0
C1
Two Common Reference Comparators with Outputs
CM<2:0> = 101
C1OUT
RA0/AN0
RA3/AN3/
VREF+
A
VIN-
A
VIN+
C1
C1OUT
C2
C2OUT
RA4/T0CKI/C1OUT*
RA1/AN1
C2
C2OUT
A
VIN-
RA2/AN2/
D
VREF-/CVREF
VIN+
RA1/AN1
RA5/AN4/SS/HLVDIN/C2OUT*
One Independent Comparator with Output
CM<2:0> = 001
A
VIN-
RA3/AN3/ A
VREF+
VIN+
RA0/AN0
C1
C1OUT
RA4/T0CKI/C1OUT*
D
VIN-
RA2/AN2/ D
VREF-/CVREF
VIN+
RA1/AN1
Four Inputs Multiplexed to Two Comparators
CM<2:0> = 110
RA0/AN0
A
RA3/AN3/
VREF+
A
RA1/AN1
A
A
RA2/AN2/
VREF-/CVREF
C2
Off (Read as ‘0’)
CIS = 0
CIS = 1
VIN-
CIS = 0
CIS = 1
VIN-
VIN+
VIN+
C1
C1OUT
C2
C2OUT
CVREF
From VREF Module
A = Analog Input, port reads zeros always
D = Digital Input
CIS (CMCON<3>) is the Comparator Input Switch
* Setting the TRISA<5:4> bits will disable the comparator outputs by configuring the pins as inputs.
DS39631E-page 234
© 2008 Microchip Technology Inc.
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20.2
20.3.2
Comparator Operation
A single comparator is shown in Figure 20-2, along with
the relationship between the analog input levels and
the digital output. When the analog input at VIN+ is less
than the analog input VIN-, the output of the comparator
is a digital low level. When the analog input at VIN+ is
greater than the analog input VIN-, the output of the
comparator is a digital high level. The shaded areas of
the output of the comparator in Figure 20-2 represent
the uncertainty, due to input offsets and response time.
20.3
Comparator Reference
Depending on the comparator operating mode, either
an external or internal voltage reference may be used.
The analog signal present at VIN- is compared to the
signal at VIN+ and the digital output of the comparator
is adjusted accordingly (Figure 20-2).
FIGURE 20-2:
SINGLE COMPARATOR
VIN+
+
VIN-
–
Output
VINVIN+
Output
20.3.1
INTERNAL REFERENCE SIGNAL
The comparator module also allows the selection of an
internally generated voltage reference from the
comparator voltage reference module. This module is
described in more detail in Section 21.0 “Comparator
Voltage Reference Module”.
The internal reference is only available in the mode
where four inputs are multiplexed to two comparators
(CM<2:0> = 110). In this mode, the internal voltage
reference is applied to the VIN+ pin of both
comparators.
20.4
Comparator Response Time
Response time is the minimum time, after selecting a
new reference voltage or input source, before the
comparator output has a valid level. If the internal reference is changed, the maximum delay of the internal
voltage reference must be considered when using the
comparator outputs. Otherwise, the maximum delay of
the comparators should be used (see Section 26.0
“Electrical Characteristics”).
20.5
Comparator Outputs
The comparator outputs are read through the CMCON
register. These bits are read-only. The comparator
outputs may also be directly output to the RA4 and RA5
I/O pins. When enabled, multiplexers in the output path
of the RA4 and RA5 pins will switch and the output of
each pin will be the unsynchronized output of the
comparator. The uncertainty of each of the
comparators is related to the input offset voltage and
the response time given in the specifications.
Figure 20-3 shows the comparator output block
diagram.
The TRISA bits will still function as an output enable/
disable for the RA4 and RA5 pins while in this mode.
EXTERNAL REFERENCE SIGNAL
When external voltage references are used, the
comparator module can be configured to have the comparators operate from the same or different reference
sources. However, threshold detector applications may
require the same reference. The reference signal must
be between VSS and VDD and can be applied to either
pin of the comparator(s).
© 2008 Microchip Technology Inc.
The polarity of the comparator outputs can be changed
using the C2INV and C1INV bits (CMCON<4:5>).
Note 1: When reading the PORT register, all pins
configured as analog inputs will read as
‘0’. Pins configured as digital inputs will
convert an analog input according to the
Schmitt Trigger 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.
DS39631E-page 235
PIC18F2420/2520/4420/4520
+
To RA4 or
RA5 pin
-
Port pins
COMPARATOR OUTPUT BLOCK DIAGRAM
MULTIPLEX
FIGURE 20-3:
D
Q
Bus
Data
CxINV
Read CMCON
EN
D
Q
EN
CL
From
Other
Comparator
Reset
20.6
Comparator Interrupts
The comparator interrupt flag is set whenever there is
a change in the output value of either comparator.
Software will need to maintain information about the
status of the output bits, as read from CMCON<7:6>, to
determine the actual change that occurred. The CMIF
bit (PIR2<6>) is the Comparator Interrupt Flag. The
CMIF bit must be reset by clearing it. Since it is also
possible to write a ‘1’ to this register, a simulated
interrupt may be initiated.
Both the CMIE bit (PIE2<6>) and the PEIE bit
(INTCON<6>) must be set to enable the interrupt. In
addition, the GIE bit (INTCON<7>) must also be set. If
any of these bits are clear, the interrupt is not enabled,
though the CMIF bit will still be set if an interrupt
condition occurs.
Note:
If a change in the CMCON register
(C1OUT or C2OUT) should occur when a
read operation is being executed (start of
the Q2 cycle), then the CMIF (PIR2<6>)
interrupt flag may not get set.
The user, in the Interrupt Service Routine, can clear the
interrupt in the following manner:
a)
b)
Set
CMIF
bit
20.7
Comparator Operation
During Sleep
When a comparator is active and the device is placed
in Sleep mode, the comparator remains active and the
interrupt is functional if enabled. This interrupt will
wake-up the device from Sleep mode when enabled.
Each operational comparator will consume additional
current, as shown in the comparator specifications. To
minimize power consumption while in Sleep mode, turn
off the comparators (CM<2:0> = 111) before entering
Sleep. If the device wakes up from Sleep, the contents
of the CMCON register are not affected.
20.8
Effects of a Reset
A device Reset forces the CMCON register to its Reset
state, causing the comparator modules to be turned off
(CM<2:0> = 111). However, the input pins (RA0
through RA3) are configured as analog inputs by
default on device Reset. The I/O configuration for these
pins is determined by the setting of the PCFG<3:0> bits
(ADCON1<3:0>). Therefore, device current is
minimized when analog inputs are present at Reset
time.
Any read or write of CMCON will end the
mismatch condition.
Clear flag bit, CMIF.
A mismatch condition will continue to set flag bit, CMIF.
Reading CMCON will end the mismatch condition and
allow flag bit, CMIF, to be cleared.
DS39631E-page 236
© 2008 Microchip Technology Inc.
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20.9
range by more than 0.6V in either direction, one of the
diodes is forward biased and a latch-up condition may
occur. A maximum source impedance of 10 kΩ is
recommended for the analog sources. Any external
component connected to an analog input pin, such as
a capacitor or a Zener diode, should have very little
leakage current.
Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 20-4. Since the analog pins are connected to a
digital output, they have reverse biased diodes to VDD
and VSS. The analog input, therefore, must be between
VSS and VDD. If the input voltage deviates from this
FIGURE 20-4:
COMPARATOR ANALOG INPUT MODEL
VDD
VT = 0.6V
RS < 10k
RIC
Comparator
Input
AIN
CPIN
5 pF
VA
VT = 0.6V
ILEAKAGE
±100 nA
VSS
CPIN
VT
ILEAKAGE
RIC
RS
VA
Legend:
TABLE 20-1:
Name
CMCON
CVRCON
INTCON
=
=
=
=
=
=
Input Capacitance
Threshold Voltage
Leakage Current at the pin due to various junctions
Interconnect Resistance
Source Impedance
Analog Voltage
REGISTERS ASSOCIATED WITH COMPARATOR MODULE
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
C2OUT
C1OUT
C2INV
C1INV
CIS
CM2
CM1
CM0
51
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
51
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
52
GIE/GIEH PEIE/GIEL
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OSCFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
IPR2
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
RA7(1)
RA6(1)
RA5
RA4
RA3
RA2
RA1
RA0
52
LATA7(1)
LATA6(1)
PORTA
LATA
TRISA
TRISA7
(1)
PORTA Data Latch Register (Read and Write to Data Latch)
TRISA6(1) PORTA Data Direction Register
52
52
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 are read as ‘0’.
© 2008 Microchip Technology Inc.
DS39631E-page 237
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NOTES:
DS39631E-page 238
© 2008 Microchip Technology Inc.
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21.0
COMPARATOR VOLTAGE
REFERENCE MODULE
The comparator voltage reference is a 16-tap resistor
ladder network that provides a selectable reference
voltage. Although its primary purpose is to provide a
reference for the analog comparators, it may also be
used independently of them.
A block diagram of the module is shown in Figure 21-1.
The resistor ladder is segmented to provide two ranges
of CVREF values and has a power-down function to
conserve power when the reference is not being used.
The module’s supply reference can be provided from
either device VDD/VSS or an external voltage reference.
is selected by the CVRR bit (CVRCON<5>). The
primary difference between the ranges is the size of the
steps selected by the CVREF Selection bits
(CVR<3:0>), with one range offering finer resolution.
The equations used to calculate the output of the
comparator voltage reference are as follows:
If CVRR = 1:
CVREF = ((CVR<3:0>)/24) x CVRSRC
If CVRR = 0:
CVREF = (CVRSRC x 1/4) + (((CVR<3:0>)/32) x
CVRSRC)
Configuring the Comparator
Voltage Reference
The comparator reference supply voltage can come
from either VDD and VSS, or the external VREF+ and
VREF- that are multiplexed with RA2 and RA3. The
voltage source is selected by the CVRSS bit
(CVRCON<4>).
The voltage reference module is controlled through the
CVRCON register (Register 21-1). The comparator
voltage reference provides two ranges of output voltage, each with 16 distinct levels. The range to be used
The settling time of the comparator voltage reference
must be considered when changing the CVREF output (see Table 26-3 in Section 26.0 “Electrical
Characteristics”).
21.1
REGISTER 21-1:
CVRCON: COMPARATOR VOLTAGE REFERENCE 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
CVREN
CVROE(1)
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 RA2/AN2/VREF-/CVREF pin
0 = CVREF voltage is disconnected from the RA2/AN2/VREF-/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
CVR3:CVR0: Comparator VREF Value Selection bits (0 ≤ (CVR<3:0>) ≤ 15)
When CVRR = 1:
CVREF = ((CVR<3:0>)/24) • (CVRSRC)
When CVRR = 0:
CVREF = (CVRSRC/4) + ((CVR<3:0>)/32) • (CVRSRC)
Note 1:
CVROE overrides the TRISA<2> bit setting.
© 2008 Microchip Technology Inc.
DS39631E-page 239
PIC18F2420/2520/4420/4520
FIGURE 21-1:
COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM
VREF+
VDD
CVRSS = 1
8R
CVRSS = 0
CVR<3:0>
R
CVREN
R
R
16-to-1 MUX
R
16 Steps
R
CVREF
R
R
CVRR
VREF-
8R
CVRSS = 1
CVRSS = 0
21.2
Voltage Reference Accuracy/Error
The full range of voltage reference cannot be realized
due to the construction of the module. The transistors
on the top and bottom of the resistor ladder network
(Figure 21-1) keep CVREF from approaching the reference source rails. The voltage reference is derived
from the reference source; therefore, the CVREF output
changes with fluctuations in that source. The tested
absolute accuracy of the voltage reference can be
found in Section 26.0 “Electrical Characteristics”.
21.3
Operation During Sleep
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.
21.4
Effects of a Reset
A device Reset disables the voltage reference by
clearing bit, CVREN (CVRCON<7>). This Reset also
disconnects the reference from the RA2 pin by clearing
bit, CVROE (CVRCON<6>) and selects the high-voltage
range by clearing bit, CVRR (CVRCON<5>). The CVR
value select bits are also cleared.
21.5
Connection Considerations
The voltage reference module operates independently
of the comparator module. The output of the reference
generator may be connected to the RA2 pin if the
CVROE bit is set. Enabling the voltage reference output onto RA2 when it is configured as a digital input will
increase current consumption. Connecting RA2 as a
digital output with CVRSS enabled will also increase
current consumption.
The RA2 pin can be used as a simple D/A output with
limited drive capability. Due to the limited current drive
capability, a buffer must be used on the voltage
reference output for external connections to VREF.
Figure 21-2 shows an example buffering technique.
DS39631E-page 240
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 21-2:
COMPARATOR VOLTAGE REFERENCE OUTPUT BUFFER EXAMPLE
PIC18FXXXX
CVREF
Module
R(1)
Voltage
Reference
Output
Impedance
Note 1:
TABLE 21-1:
Name
CVRCON
CMCON
TRISA
+
–
RA2
CVREF Output
R is dependent upon the comparator voltage reference configuration bits, CVRCON<3:0> and CVRCON<5>.
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
CVREN
CVROE
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
51
C2OUT
C1OUT
C2INV
C1INV
CIS
CM2
CM1
CM0
51
TRISA7(1) TRISA6(1) PORTA Data Direction Register
52
Legend: Shaded cells are not used with the comparator voltage reference.
Note 1: PORTA pins are enabled based on oscillator configuration.
© 2008 Microchip Technology Inc.
DS39631E-page 241
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NOTES:
DS39631E-page 242
© 2008 Microchip Technology Inc.
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22.0
HIGH/LOW-VOLTAGE
DETECT (HLVD)
PIC18F2420/2520/4420/4520
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.
REGISTER 22-1:
R/W-0
The block diagram for the HLVD module is shown in
Figure 22-1.
HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER
U-0
VDIRMAG
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.
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 bit, read as ‘0’
-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.
© 2008 Microchip Technology Inc.
Advance Information
DS39631E-page 243
PIC18F2420/2520/4420/4520
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.
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.
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.
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 (HLVDCON<3:0>).
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
FIGURE 22-1:
VDD
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
HLVDCON
Register
HLVDEN
HLVDIN
16-to-1 MUX
HLVDIN
HLVDL<3:0>
VDIRMAG
Set
HLVDIF
HLVDEN
BOREN
DS39631E-page 244
Internal Voltage
Reference
Advance Information
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 (PIR2<2>), which
may have been set from a previous interrupt.
Enable the HLVD interrupt, if interrupts are
desired, by setting the HLVDIE and GIE bits
(PIE2<2> and INTCON<7>). An interrupt will not
be generated until the IRVST bit is set.
22.3
22.4
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 D022B.
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.
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.
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
VLVD
HLVDIF
Enable HLVD
TIRVST
IRVST
Internal Reference is Stable
HLVDIF Cleared in Software
CASE 2:
VDD
VLVD
HLVDIF
Enable HLVD
TIRVST
IRVST
Internal Reference is Stable
HLVDIF Cleared in Software
HLVDIF cleared in software,
HLVDIF remains set since HLVD condition still exists
© 2008 Microchip Technology Inc.
Advance Information
DS39631E-page 245
PIC18F2420/2520/4420/4520
FIGURE 22-3:
HIGH-VOLTAGE DETECT OPERATION (VDIRMAG = 1)
CASE 1:
HLVDIF may not be set
VLVD
VDD
HLVDIF
Enable HLVD
TIRVST
IRVST
HLVDIF Cleared in Software
Internal Reference is Stable
CASE 2:
VLVD
VDD
HLVDIF
Enable HLVD
TIRVST
IRVST
Internal Reference is Stable
HLVDIF Cleared in Software
HLVDIF cleared in software,
HLVDIF remains set since HLVD condition still exists
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).
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.
DS39631E-page 246
TYPICAL LOW-VOLTAGE
DETECT APPLICATION
VA
VB
Voltage
22.5
Time
TA
TB
Legend: VA = HLVD trip point
VB = Minimum valid device
operating voltage
Advance Information
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
22.6
Operation During Sleep
22.7
When enabled, the HLVD circuitry continues to operate
during Sleep. If the device voltage crosses the trip
point, the HLVDIF bit will be set and the device will
wake-up from Sleep. Device execution will continue
from the interrupt vector address if interrupts have
been globally enabled.
TABLE 22-1:
Effects of a Reset
A device Reset forces all registers to their Reset state.
This forces the HLVD module to be turned off.
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
50
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
PIR2
OSCFIF
CMIF
—
EEIF
BCLIF
HLVDIF
TMR3IF
CCP2IF
52
PIE2
OCSFIE
CMIE
—
EEIE
BCLIE
HLVDIE
TMR3IE
CCP2IE
52
IPR2
OSCFIP
CMIP
—
EEIP
BCLIP
HLVDIP
TMR3IP
CCP2IP
52
Legend: — = unimplemented, read as ‘0’. Shaded cells are unused by the HLVD module.
© 2008 Microchip Technology Inc.
Advance Information
DS39631E-page 247
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 248
Advance Information
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
23.0
SPECIAL FEATURES OF
THE CPU
PIC18F2420/2520/4420/4520 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)
• Fail-Safe Clock Monitor
• Two-Speed Start-up
• Code Protection
• ID Locations
• In-Circuit Serial Programming
All of these features are enabled and configured by
setting the appropriate Configuration register bits.
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.
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 Configurations”.
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, PIC18F2420/2520/4420/
4520 devices have a Watchdog Timer, which is either
permanently enabled via the Configuration bits or
software controlled (if configured as disabled).
TABLE 23-1:
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.
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”.
CONFIGURATION BITS AND DEVICE IDs
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
FOSC1
FOSC0
Default/
Unprogrammed
Value
300001h
CONFIG1H
IESO
FCMEN
—
—
FOSC3
FOSC2
300002h
CONFIG2L
—
—
—
BORV1
BORV0
BOREN1
—
—
—
WDTPS3
WDTPS2
WDTPS1 WDTPS0
WDTEN
—
—
—
—
LPT1OSC PBADEN
CCP2MX
1--- -011
10-- -1-1
BOREN0 PWRTEN
00-- 0111
---1 1111
300003h
CONFIG2H
300005h
CONFIG3H MCLRE
300006h
CONFIG4L
DEBUG
XINST
—
—
—
LVP
—
STVREN
300008h
CONFIG5L
—
—
—
—
CP3(1)
CP2(1)
CP1
CP0
---- 1111
300009h
CONFIG5H
CPD
CPB
—
—
—
—
—
—
11-- ----
30000Ah
CONFIG6L
—
—
—
—
WRT3(1)
WRT2(1)
WRT1
WRT0
---- 1111
30000Bh
CONFIG6H
WRTD
WRTB
WRTC
—
—
—
—
—
111- ----
(1)
(1)
---1 1111
30000Ch
CONFIG7L
—
—
—
—
EBTR1
EBTR0
---- 1111
30000Dh
CONFIG7H
—
EBTRB
—
—
—
—
—
—
-1-- ----
3FFFFEh DEVID1
DEV2
DEV1
DEV0
REV4
REV3
REV2
REV1
REV0
xxxx xxxx(2)
3FFFFFh
DEVID2
DEV10
DEV9
DEV8
DEV7
DEV6
DEV5
DEV4
DEV3
xxxx xxxx(2)
Legend:
x = unknown, u = unchanged, — = unimplemented, q = value depends on condition.
Shaded cells are unimplemented, read as ‘0’.
Unimplemented in PIC18F2420/4420 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:
© 2008 Microchip Technology Inc.
EBTR3
EBTR2
DS39631E-page 249
PIC18F2420/2520/4420/4520
REGISTER 23-1:
CONFIG1H: CONFIGURATION REGISTER 1 HIGH (BYTE ADDRESS 300001h)
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’
u = Unchanged from programmed state
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, CLKO function on RA6
101x = External RC oscillator, CLKO function on RA6
1001 = Internal oscillator block, CLKO 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, CLKO function on RA6
0011 = External RC oscillator, CLKO function on RA6
0010 = HS oscillator
0001 = XT oscillator
0000 = LP oscillator
DS39631E-page 250
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-2:
U-0
CONFIG2L: CONFIGURATION REGISTER 2 LOW (BYTE ADDRESS 300002h)
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’
u = Unchanged from programmed state
bit 7-5
Unimplemented: Read as ‘0’
bit 4-3
BORV<1:0>: Brown-out Reset Voltage bits(1)
11 = Minimum setting
.
.
.
00 = Maximum setting
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.
© 2008 Microchip Technology Inc.
DS39631E-page 251
PIC18F2420/2520/4420/4520
REGISTER 23-3:
CONFIG2H: CONFIGURATION REGISTER 2 HIGH (BYTE ADDRESS 300003h)
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’
u = Unchanged from programmed state
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 enabled
0 = WDT disabled (control is placed on the SWDTEN bit)
DS39631E-page 252
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-4:
CONFIG3H: CONFIGURATION REGISTER 3 HIGH (BYTE ADDRESS 300005h)
R/P-1
U-0
U-0
U-0
U-0
R/P-0
R/P-1
R/P-1
MCLRE
—
—
—
—
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’
u = Unchanged from programmed state
bit 7
MCLRE: MCLR Pin Enable bit
1 = MCLR pin enabled; RE3 input pin disabled
0 = RE3 input pin enabled; MCLR disabled
bit 6-3
Unimplemented: Read as ‘0’
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 ADCON1 Reset state. ADCON1 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:
CONFIG4L: CONFIGURATION REGISTER 4 LOW (BYTE ADDRESS 300006h)
R/P-1
R/P-0
U-0
U-0
U-0
R/P-1
U-0
R/P-1
DEBUG
XINST
—
—
—
LVP
—
STVREN
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
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
© 2008 Microchip Technology Inc.
DS39631E-page 253
PIC18F2420/2520/4420/4520
REGISTER 23-6:
U-0
CONFIG5L: CONFIGURATION REGISTER 5 LOW (BYTE ADDRESS 300008h)
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
C = Clearable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
bit 7-4
Unimplemented: Read as ‘0’
bit 3
CP3: Code Protection bit(1)
1 = Block 3 (006000-007FFFh) not code-protected
0 = Block 3 (006000-007FFFh) code-protected
bit 2
CP2: Code Protection bit(1)
1 = Block 2 (004000-005FFFh) not code-protected
0 = Block 2 (004000-005FFFh) code-protected
bit 1
CP1: Code Protection bit
1 = Block 1 (002000-003FFFh) not code-protected
0 = Block 1 (002000-003FFFh) code-protected
bit 0
CP0: Code Protection bit
1 = Block 0 (000800-001FFFh) not code-protected
0 = Block 0 (000800-001FFFh) code-protected
Note 1:
Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
REGISTER 23-7:
CONFIG5H: CONFIGURATION REGISTER 5 HIGH (BYTE ADDRESS 300009h)
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
C = Clearable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
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 (000000-0007FFh) not code-protected
0 = Boot block (000000-0007FFh) code-protected
bit 5-0
Unimplemented: Read as ‘0’
DS39631E-page 254
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-8:
U-0
CONFIG6L: CONFIGURATION REGISTER 6 LOW (BYTE ADDRESS 30000Ah)
U-0
—
—
U-0
—
U-0
—
R/C-1
WRT3
(1)
R/C-1
(1)
WRT2
R/C-1
R/C-1
WRT1
WRT0
bit 7
bit 0
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
bit 7-4
Unimplemented: Read as ‘0’
bit 3
WRT3: Write Protection bit(1)
1 = Block 3 (006000-007FFFh) not write-protected
0 = Block 3 (006000-007FFFh) write-protected
bit 2
WRT2: Write Protection bit(1)
1 = Block 2 (004000-005FFFh) not write-protected
0 = Block 2 (004000-005FFFh) write-protected
bit 1
WRT1: Write Protection bit
1 = Block 1 (002000-003FFFh) not write-protected
0 = Block 1 (002000-003FFFh) write-protected
bit 0
WRT0: Write Protection bit
1 = Block 0 (000800-001FFFh) not write-protected
0 = Block 0 (000800-001FFFh) write-protected
Note 1:
Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
REGISTER 23-9:
R/C-1
WRTD
CONFIG6H: CONFIGURATION REGISTER 6 HIGH (BYTE ADDRESS 30000Bh)
R/C-1
R/C-1
U-0
U-0
U-0
U-0
U-0
WRTB
WRTC(1)
—
—
—
—
—
bit 7
bit 0
Legend:
R = Readable bit
C = Clearable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
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 (000000-0007FFh) not write-protected
0 = Boot block (000000-0007FFh) write-protected
bit 5
WRTC: Configuration Register Write Protection bit(1)
1 = Configuration registers (300000-3000FFh) not write-protected
0 = Configuration registers (300000-3000FFh) 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.
© 2008 Microchip Technology Inc.
DS39631E-page 255
PIC18F2420/2520/4420/4520
REGISTER 23-10: CONFIG7L: CONFIGURATION REGISTER 7 LOW (BYTE ADDRESS 30000Ch)
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
C = Clearable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
bit 7-4
Unimplemented: Read as ‘0’
bit 3
EBTR3: Table Read Protection bit(1)
1 = Block 3 (006000-007FFFh) not protected from table reads executed in other blocks
0 = Block 3 (006000-007FFFh) protected from table reads executed in other blocks
bit 2
EBTR2: Table Read Protection bit(1)
1 = Block 2 (004000-005FFFh) not protected from table reads executed in other blocks
0 = Block 2 (004000-005FFFh) protected from table reads executed in other blocks
bit 1
EBTR1: Table Read Protection bit
1 = Block 1 (002000-003FFFh) not protected from table reads executed in other blocks
0 = Block 1 (002000-003FFFh) protected from table reads executed in other blocks
bit 0
EBTR0: Table Read Protection bit
1 = Block 0 (000800-001FFFh) not protected from table reads executed in other blocks
0 = Block 0 (000800-001FFFh) protected from table reads executed in other blocks
Note 1:
Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
REGISTER 23-11: CONFIG7H: CONFIGURATION REGISTER 7 HIGH (BYTE ADDRESS 30000Dh)
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
C = Clearable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
bit 7
Unimplemented: Read as ‘0’
bit 6
EBTRB: Boot Block Table Read Protection bit
1 = Boot block (000000-0007FFh) not protected from table reads executed in other blocks
0 = Boot block (000000-0007FFh) protected from table reads executed in other blocks
bit 5-0
Unimplemented: Read as ‘0’
DS39631E-page 256
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-12: DEVID1: DEVICE ID REGISTER 1 FOR PIC18F2420/2520/4420/4520
R
R
R
R
R
R
R
R
DEV2
DEV1
DEV0
REV4
REV3
REV2
REV1
REV0
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
bit 7-5
DEV<2:0>: Device ID bits
110 = PIC18F4420
100 = PIC18F4520
010 = PIC18F2420
000 = PIC18F2520
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 PIC18F2420/2520/4420/4520
R
R
R
R
R
R
R
R
DEV10(1)
DEV9(1)
DEV8(1)
DEV7(1)
DEV6(1)
DEV5(1)
DEV4(1)
DEV3(1)
bit 7
bit 0
Legend:
R = Read-only bit
P = Programmable bit
-n = Value when device is unprogrammed
bit 7-0
Note 1:
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
DEV<10:3>: Device ID bits(1)
These bits are used with the DEV<2:0> bits in Device ID Register 1 to identify the part number.
0001 0001 = PIC18F2420/2520 devices
0001 0000 = PIC18F4420/4520 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.
© 2008 Microchip Technology Inc.
DS39631E-page 257
PIC18F2420/2520/4420/4520
23.2
Watchdog Timer (WDT)
For PIC18F2420/2520/4420/4520 devices, the WDT is
driven by the INTRC 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
INTRC 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 (OSCCON<6:4>) are changed or a clock
failure has occurred.
FIGURE 23-1:
Note 1: The CLRWDT and SLEEP instructions
clear the WDT and postscaler counts
when executed.
2: Changing the setting of the IRCF bits
(OSCCON<6:4>) clears the WDT and
postscaler counts.
3: When a CLRWDT instruction is executed,
the postscaler count will be cleared.
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.
WDT BLOCK DIAGRAM
SWDTEN
WDTEN
Enable WDT
WDT Counter
INTRC Source
Wake-up from
Power-Managed
Modes
÷128
Change on IRCF bits
Programmable Postscaler
1:1 to 1:32,768
CLRWDT
Reset
WDT
Reset
All Device Resets
WDTPS<3:0>
4
Sleep
DS39631E-page 258
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 Controlled Watchdog Timer Enable bit(1)
1 = Watchdog Timer is on
0 = Watchdog Timer is off
Note 1:
This bit has no effect if the Configuration bit, WDTEN, is enabled.
TABLE 23-2:
Name
RCON
WDTCON
x = Bit is unknown
SUMMARY OF WATCHDOG TIMER REGISTERS
Bit 0
Reset
Values
on page
POR
BOR
48
—
SWDTEN(2)
50
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
IPEN
SBOREN(1)
—
RI
TO
PD
—
—
—
—
—
—
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Watchdog Timer.
Note 1: 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)”.
2: This bit has no effect if the Configuration bit, WDTEN, is enabled.
© 2008 Microchip Technology Inc.
DS39631E-page 259
PIC18F2420/2520/4420/4520
23.3
In all other power-managed modes, Two-Speed Startup is not used. The device will be clocked by the
currently selected clock source until the primary clock
source becomes available. The setting of the IESO bit
is ignored.
Two-Speed Start-up
The Two-Speed Start-up feature helps to minimize the
latency period from oscillator start-up to code execution
by allowing the microcontroller to use the INTOSC
oscillator as a clock source until the primary clock
source is available. It is enabled by setting the IESO
Configuration bit.
23.3.1
Two-Speed Start-up should be enabled only if the
primary oscillator mode is LP, XT, HS or HSPLL
(Crystal-Based modes). Other sources do not require
an OST start-up delay; for these, Two-Speed Start-up
should be disabled.
While using the INTOSC oscillator in Two-Speed Startup, the device still obeys the normal command
sequences for entering power-managed modes,
including multiple SLEEP instructions (refer to
Section 3.1.4 “Multiple Sleep Commands”). In
practice, this means that user code can change the
SCS<1:0> bit settings or issue SLEEP instructions
before the OST times out. This would allow an
application to briefly wake-up, perform routine
“housekeeping” tasks and return to Sleep before the
device starts to operate from the primary oscillator.
When enabled, Resets and wake-ups from Sleep mode
cause the device to configure itself to run from the
internal oscillator block as the clock source, following
the time-out of the Power-up Timer after a Power-on
Reset is enabled. This allows almost immediate code
execution while the primary oscillator starts and the
OST is running. Once the OST times out, the device
automatically switches to PRI_RUN mode.
User code can also check if the primary clock source is
currently providing the device clocking by checking the
status of the OSTS bit (OSCCON<3>). If the bit is set,
the primary oscillator is providing the clock. Otherwise,
the internal oscillator block is providing the clock during
wake-up from Reset or Sleep mode.
To use a higher clock speed on wake-up, the INTOSC
or postscaler clock sources can be selected to provide
a higher clock speed by setting bits, IRCF<2:0>,
immediately after Reset. For wake-ups from Sleep, the
INTOSC or postscaler clock sources can be selected
by setting the IRCF<2:0> bits prior to entering Sleep
mode.
FIGURE 23-2:
SPECIAL CONSIDERATIONS FOR
USING TWO-SPEED START-UP
TIMING TRANSITION FOR TWO-SPEED START-UP (INTOSC TO HSPLL)
Q1
Q3
Q2
Q4
Q2 Q3 Q4 Q1 Q2 Q3
Q1
INTOSC
Multiplexer
OSC1
TOST(1)
TPLL(1)
1
PLL Clock
Output
2
n-1 n
Clock
Transition(2)
CPU Clock
Peripheral
Clock
Program
Counter
PC
Wake from Interrupt Event
Note 1:
2:
DS39631E-page 260
PC + 2
PC + 6
PC + 4
OSTS bit Set
TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
Clock transition typically occurs within 2-4 TOSC.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
23.4
Fail-Safe Clock Monitor
The Fail-Safe Clock Monitor (FSCM) allows the microcontroller to continue operation in the event of an external
oscillator failure by automatically switching the device
clock to the internal oscillator block. The FSCM function
is enabled by setting the FCMEN Configuration bit.
When FSCM is enabled, the INTRC oscillator runs at
all times to monitor clocks to peripherals and provide a
backup clock in the event of a clock failure. Clock
monitoring (shown in Figure 23-3) is accomplished by
creating a sample clock signal, which is the INTRC output divided by 64. This allows ample time between
FSCM sample clocks for a peripheral clock edge to
occur. The peripheral device clock and the sample
clock are presented as inputs to the Clock Monitor latch
(CM). The CM is set on the falling edge of the device
clock source, but cleared on the rising edge of the
sample clock.
FIGURE 23-3:
FSCM BLOCK DIAGRAM
Clock Monitor
Latch (CM)
(edge-triggered)
Peripheral
Clock
INTRC
Source
÷ 64
(32 μs)
488 Hz
(2.048 ms)
S
Q
C
Q
Clock
Failure
Detected
Clock failure is tested for on the falling edge of the
sample clock. If a sample clock falling edge occurs
while CM is still set, a clock failure has been detected
(Figure 23-4). This causes the following:
• the FSCM generates an oscillator fail interrupt by
setting bit, OSCFIF (PIR2<7>);
• the device clock source is switched to the internal
oscillator block (OSCCON is not updated to show
the current clock source – this is the fail-safe
condition) and
• the WDT is reset.
During switchover, the postscaler frequency from the
internal oscillator block may not be sufficiently stable for
timing sensitive applications. In these cases, it may be
desirable to select another clock configuration and enter
an alternate power-managed mode. This can be done to
© 2008 Microchip Technology Inc.
attempt a partial recovery or execute a controlled shutdown. See Section 3.1.4 “Multiple Sleep Commands”
and Section 23.3.1 “Special Considerations for
Using Two-Speed Start-up” for more details.
To use a higher clock speed on wake-up, the INTOSC or
postscaler clock sources can be selected to provide a
higher clock speed by setting bits, IRCF<2:0>, immediately after Reset. For wake-ups from Sleep, the INTOSC
or postscaler clock sources can be selected by setting the
IRCF<2:0> bits prior to entering Sleep mode.
The FSCM will detect failures of the primary or secondary clock sources only. If the internal oscillator block
fails, no failure would be detected, nor would any action
be possible.
23.4.1
FSCM AND THE WATCHDOG TIMER
Both the FSCM and the WDT are clocked by the
INTRC oscillator. Since the WDT operates with a
separate divider and counter, disabling the WDT has
no effect on the operation of the INTRC oscillator when
the FSCM is enabled.
As already noted, the clock source is switched to the
INTOSC clock when a clock failure is detected.
Depending on the frequency selected by the
IRCF<2:0> bits, this may mean a substantial change in
the speed of code execution. If the WDT is enabled
with a small prescale value, a decrease in clock speed
allows a WDT time-out to occur and a subsequent
device Reset. For this reason, fail-safe clock events
also reset the WDT and postscaler, allowing it to start
timing from when execution speed was changed and
decreasing the likelihood of an erroneous time-out.
23.4.2
EXITING FAIL-SAFE OPERATION
The fail-safe condition is terminated by either a device
Reset or by entering a power-managed mode. On
Reset, the controller starts the primary clock source
specified in Configuration Register 1H (with any
required start-up delays that are required for the oscillator mode, such as the OST or PLL timer). The
INTOSC multiplexer provides the device clock until the
primary clock source becomes ready (similar to a TwoSpeed Start-up). The clock source is then switched to
the primary clock (indicated by the OSTS bit in the
OSCCON register becoming set). The Fail-Safe Clock
Monitor then resumes monitoring the peripheral clock.
The primary clock source may never become ready during start-up. In this case, operation is clocked by the
INTOSC multiplexer. The OSCCON register will remain
in its Reset state until a power-managed mode is
entered.
DS39631E-page 261
PIC18F2420/2520/4420/4520
FIGURE 23-4:
FSCM TIMING DIAGRAM
Sample Clock
Oscillator
Failure
Device
Clock
Output
CM Output
(Q)
Failure
Detected
OSCFIF
CM Test
Note:
23.4.3
FSCM INTERRUPTS IN
POWER-MANAGED MODES
By entering a power-managed mode, the clock multiplexer selects the clock source selected by the OSCCON
register. Fail-Safe Clock Monitoring of the powermanaged clock source resumes in the power-managed
mode.
If an oscillator failure occurs during power-managed
operation, the subsequent events depend on whether
or not the oscillator failure interrupt is enabled. If
enabled (OSCFIF = 1), code execution will be clocked
by the INTOSC multiplexer. An automatic transition
back to the failed clock source will not occur.
If the interrupt is disabled, subsequent interrupts while
in Idle mode will cause the CPU to begin executing
instructions while being clocked by the INTOSC
source.
23.4.4
CM Test
CM Test
The device clock is normally at a much higher frequency than the sample clock. The relative frequencies in this
example have been chosen for clarity.
POR OR WAKE FROM SLEEP
The FSCM is designed to detect oscillator failure at any
point after the device has exited Power-on Reset
(POR) or low-power Sleep mode. When the primary
device clock is EC, RC or INTRC modes, monitoring
can begin immediately following these events.
time considerably longer than the FCSM sample clock
time, a false clock failure may be detected. To prevent
this, the internal oscillator block is automatically configured as the device clock and functions until the primary
clock is stable (the OST and PLL timers have timed
out). This is identical to Two-Speed Start-up mode.
Once the primary clock is stable, the INTRC returns to
its role as the FSCM source.
Note:
The same logic that prevents false oscillator failure interrupts on POR, or wake from
Sleep, will also prevent the detection of
the oscillator’s failure to start at all following these events. This can be avoided by
monitoring the OSTS bit and using a
timing routine to determine if the oscillator
is taking too long to start. Even so, no
oscillator failure interrupt will be flagged.
As noted in Section 23.3.1 “Special Considerations
for Using Two-Speed Start-up”, it is also possible to
select another clock configuration and enter an
alternate power-managed mode while waiting for the
primary clock to become stable. When the new powermanaged mode is selected, the primary clock is
disabled.
For oscillator modes involving a crystal or resonator
(HS, HSPLL, LP or XT), the situation is somewhat
different. Since the oscillator may require a start-up
DS39631E-page 262
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
23.5
Each of the five blocks has three code protection bits
associated with them. They are:
Program Verification and
Code Protection
The overall structure of the code protection on the
PIC18 Flash devices differs significantly from other
PIC® devices.
• Code-Protect bit (CPn)
• Write-Protect bit (WRTn)
• External Block Table Read bit (EBTRn)
The user program memory is divided into five blocks.
One of these is a boot block of 2 Kbytes. The remainder
of the memory is divided into four blocks on binary
boundaries.
Figure 23-5 shows the program memory organization
for 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.
FIGURE 23-5:
CODE-PROTECTED PROGRAM MEMORY FOR
PIC18F2420/2520/4420/4520
MEMORY SIZE/DEVICE
Block Code Protection
Controlled By:
16 Kbytes
32 Kbytes
Address
(PIC18F2420/4420) (PIC18F2520/4520) Range
Boot Block
Boot Block
Block 0
Block 0
000000h
0007FFh
CPB, WRTB, EBTRB
000800h
CP0, WRT0, EBTR0
001FFFh
002000h
Block 1
Block 1
CP1, WRT1, EBTR1
003FFFh
004000h
CP2, WRT2, EBTR2
Block 2
005FFFh
006000h
Block 3
CP3, WRT3, EBTR3
007FFFh
Unimplemented
Read ‘0’s
Unimplemented
Read ‘0’s
(Unimplemented Memory Space)
1FFFFFh
TABLE 23-3:
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: Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
© 2008 Microchip Technology Inc.
DS39631E-page 263
PIC18F2420/2520/4420/4520
23.5.1
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 23-6 through 23-8 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 set to ‘0’, a table read instruction that executes from
within that block is allowed to read. A table read
FIGURE 23-6:
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
TBLPTR = 0008FFh
PC = 001FFEh
WRTB, EBTRB = 11
WRT0, EBTR0 = 01
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.
DS39631E-page 264
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 23-7:
EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
WRTB, EBTRB = 11
0007FFh
000800h
TBLPTR = 0008FFh
WRT0, EBTR0 = 10
001FFFh
002000h
PC = 003FFEh
WRT1, EBTR1 = 11
TBLRD*
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 23-8:
EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
0007FFh
000800h
TBLPTR = 0008FFh
PC = 001FFEh
WRTB, EBTRB = 11
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.
© 2008 Microchip Technology Inc.
DS39631E-page 265
PIC18F2420/2520/4420/4520
23.5.2
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.
23.5.3
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
read-only. WRTC can only be written via ICSP or an
external programmer.
23.6
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.
23.7
In-Circuit Serial Programming
PIC18F2420/2520/4420/4520 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.
23.8
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:
23.9
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. If a block erase is to
be performed when using Low-Voltage Programming,
the device must be supplied with VDD of 4.5V to 5.5V.
RB6, RB7
Stack:
2 levels
Program Memory:
512 bytes
Data Memory:
10 bytes
DS39631E-page 266
To use the In-Circuit Debugger function of the microcontroller, the design must implement In-Circuit Serial
Programming connections to MCLR/VPP/RE3, VDD,
VSS, RB7 and RB6. This will interface to the In-Circuit
Debugger module available from Microchip or one of
the third party development tool companies.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
24.0
INSTRUCTION SET SUMMARY
PIC18F2420/2520/4420/4520 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 μs. If a conditional test is
true, or the program counter is changed as a result of
an instruction, the instruction execution time is 2 μs.
Two-word branch instructions (if true) would take 3 μs.
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.
© 2008 Microchip Technology Inc.
DS39631E-page 267
PIC18F2420/2520/4420/4520
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 New).
DS39631E-page 268
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 24-1:
GENERAL FORMAT FOR INSTRUCTIONS
Byte-oriented file register operations
15
10
9
OPCODE
Example Instruction
8 7
d
0
a
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
0
OPCODE
15
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
0
OPCODE b (BIT #) a
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
0
OPCODE
k (literal)
MOVLW 7Fh
k = 8-bit immediate value
Control operations
CALL, GOTO and Branch operations
15
8 7
0
OPCODE
15
n<7:0> (literal)
12 11
GOTO Label
0
n<19:8> (literal)
1111
n = 20-bit immediate value
15
8 7
S
OPCODE
15
0
n<7:0> (literal)
12 11
CALL MYFUNC
0
n<19:8> (literal)
1111
S = Fast bit
15
11 10
OPCODE
15
0
n<10:0> (literal)
8 7
OPCODE
© 2008 Microchip Technology Inc.
BRA MYFUNC
0
n<7:0> (literal)
BC MYFUNC
DS39631E-page 269
PIC18F2420/2520/4420/4520
TABLE 24-2:
PIC18FXXXX INSTRUCTION SET
Mnemonic,
Operands
16-Bit Instruction Word
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 the 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:
DS39631E-page 270
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
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
0010
0001
0110
0001
0110
0110
0110
0000
0010
0100
0010
0011
0100
0001
0101
1100
1111
0110
0000
0110
0011
0100
0011
0100
0110
0101
01da
00da
01da
101a
11da
001a
010a
000a
01da
11da
11da
10da
11da
10da
00da
00da
ffff
ffff
111a
001a
110a
01da
01da
00da
00da
100a
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 the 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:
© 2008 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
DS39631E-page 271
PIC18F2420/2520/4420/4520
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 the 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.
DS39631E-page 272
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 (default).
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).
© 2008 Microchip Technology Inc.
DS39631E-page 273
PIC18F2420/2520/4420/4520
ADDWFC
ADD W and Carry bit to f
ANDLW
AND Literal with W
Syntax:
ADDWFC
Syntax:
ANDLW
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
f {,d {,a}}
Operation:
(W) + (f) + (C) → dest
Status Affected:
N,OV, C, DC, Z
Encoding:
0010
Description:
00da
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 (default).
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
Operands:
0 ≤ k ≤ 255
Operation:
(W) .AND. k → W
Status Affected:
N, Z
Encoding:
ffff
k
0000
1011
kkkk
kkkk
Description:
The contents of W are ANDed 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
=
DS39631E-page 274
REG, 0, 1
1
02h
4Dh
0
02h
50h
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 ANDed 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 (default).
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
© 2008 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)
DS39631E-page 275
PIC18F2420/2520/4420/4520
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 (default).
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 =
DS39631E-page 276
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)
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
BNC
Branch if Not Carry
BNN
Branch if Not Negative
Syntax:
BNC
Syntax:
BNN
n
n
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:
1110
0011
nnnn
nnnn
Encoding:
1110
0111
nnnn
nnnn
Description:
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:
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.
Words:
1
Words:
1
Cycles:
1(2)
Cycles:
1(2)
Q Cycle Activity:
If Jump:
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)
© 2008 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)
DS39631E-page 277
PIC18F2420/2520/4420/4520
BNOV
Branch if Not Overflow
BNZ
Branch if Not Zero
Syntax:
BNOV
Syntax:
BNZ
n
n
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:
1110
0101
nnnn
nnnn
Encoding:
1110
0001
nnnn
nnnn
Description:
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:
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.
Words:
1
Words:
1
Cycles:
1(2)
Cycles:
1(2)
Q Cycle Activity:
If Jump:
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
DS39631E-page 278
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)
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
BRA
Unconditional Branch
BSF
Bit Set f
Syntax:
BRA
Syntax:
BSF
Operands:
0 ≤ f ≤ 255
0≤b≤7
a ∈ [0,1]
Operation:
1 → f<b>
Status Affected:
None
n
Operands:
-1024 ≤ n ≤ 1023
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
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 (default).
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
© 2008 Microchip Technology Inc.
FLAG_REG, 7, 1
=
0Ah
=
8Ah
DS39631E-page 279
PIC18F2420/2520/4420/4520
BTFSC
Bit Test File, Skip if Clear
BTFSS
Bit Test File, Skip if Set
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
Description:
bbba
ffff
ffff
Encoding:
1010
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 (default).
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:
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:
bbba
ffff
ffff
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 (default).
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
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
DS39631E-page 280
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)
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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:
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 (default).
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.
n
1110
0100
nnnn
nnnn
Description:
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:
Words:
1
Q1
Q2
Q3
Q4
Cycles:
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:
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]
© 2008 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)
DS39631E-page 281
PIC18F2420/2520/4420/4520
BZ
Branch if Zero
CALL
Subroutine Call
Syntax:
BZ
Syntax:
CALL k {,s}
n
Operands:
-128 ≤ n ≤ 127
Operands:
Operation:
if Zero bit is ‘1’,
(PC) + 2 + 2n → PC
0 ≤ k ≤ 1048575
s ∈ [0,1]
Operation:
Status Affected:
None
(PC) + 4 → TOS,
k → PC<20:1>;
if s = 1,
(W) → WS,
(STATUS) → STATUSS,
(BSR) → BSRS
Status Affected:
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
If No Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
HERE
Before Instruction
PC
After Instruction
If Zero
PC
If Zero
PC
DS39631E-page 282
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
CLRF
Clear f
Syntax:
CLRF
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
f {,a}
Operation:
000h → f,
1→Z
Status Affected:
Z
Encoding:
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 (default).
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
© 2008 Microchip Technology Inc.
0000
Description:
0000
0000
0100
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
DS39631E-page 283
PIC18F2420/2520/4420/4520
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 (default).
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
f {,a}
001a
ffff
ffff
Description:
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 (default).
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
=
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
REG, 0, 0
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:
DS39631E-page 284
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)
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 (default).
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)
© 2008 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 (default).
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)
DS39631E-page 285
PIC18F2420/2520/4420/4520
DAW
Decimal Adjust W Register
DECF
Decrement f
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:
Encoding:
0000
0000
0000
DAW adjusts the 8-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
Example 1:
DAW
=
=
=
A5h
0
0
05h
1
0
ffff
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Before Instruction
W
=
C
=
DC
=
After Instruction
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 (default).
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.
0111
Description:
01da
Description:
C
Encoding:
W
C
DC
Example 2:
0000
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
=
=
=
DS39631E-page 286
CEh
0
0
34h
1
0
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
DECFSZ
Decrement f, Skip if 0
DCFSNZ
Decrement f, Skip if Not 0
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
11da
ffff
ffff
Description:
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 (default).
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.
Encoding:
0100
Description:
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
Words:
1
Cycles:
1(2)
Note:
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)
© 2008 Microchip Technology Inc.
ffff
ffff
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
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 (default).
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.
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)
DS39631E-page 287
PIC18F2420/2520/4420/4520
GOTO
Unconditional Branch
INCF
Increment f
Syntax:
GOTO k
Syntax:
INCF
Operands:
0 ≤ k ≤ 1048575
Operands:
Operation:
k → PC<20:1>
Status Affected:
None
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
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
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 (default).
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:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
GOTO THERE
After Instruction
PC =
Address (THERE)
Example:
INCF
Before Instruction
CNT
=
Z
=
C
=
DC
=
After Instruction
CNT
=
Z
=
C
=
DC
=
DS39631E-page 288
CNT, 1, 0
FFh
0
?
?
00h
1
1
1
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
11da
ffff
ffff
Encoding:
0100
Description:
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 (default).
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:
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 (default).
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:
10da
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)
© 2008 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)
DS39631E-page 289
PIC18F2420/2520/4420/4520
IORLW
Inclusive OR Literal with W
IORWF
Inclusive OR W with f
Syntax:
IORLW k
Syntax:
IORWF
Operands:
0 ≤ k ≤ 255
Operands:
Operation:
(W) .OR. k → W
Status Affected:
N, Z
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(W) .OR. (f) → dest
Status Affected:
N, Z
Encoding:
0000
1001
kkkk
kkkk
Description:
The contents of W are ORed with the
8-bit literal ‘k’. The result is placed in W.
Words:
1
Cycles:
1
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 (default).
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
=
DS39631E-page 290
RESULT, 0, 1
13h
91h
13h
93h
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
LFSR
Load FSR
MOVF
Move f
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
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 (default).
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
© 2008 Microchip Technology Inc.
REG, 0, 0
=
=
22h
FFh
=
=
22h
22h
DS39631E-page 291
PIC18F2420/2520/4420/4520
MOVFF
Move f to f
MOVLB
Move Literal to Low Nibble in BSR
Syntax:
MOVFF fs,fd
Syntax:
MOVLW k
Operands:
0 ≤ fs ≤ 4095
0 ≤ fd ≤ 4095
Operands:
0 ≤ k ≤ 255
Operation:
k → BSR
None
Operation:
(fs) → fd
Status Affected:
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)
0000
0001
kkkk
kkkk
Description:
The 8-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
DS39631E-page 292
REG1, REG2
=
=
33h
11h
=
=
33h
33h
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
MOVLW
Move Literal to W
MOVWF
Move W to f
Syntax:
MOVLW k
Syntax:
MOVWF
Operands:
0 ≤ k ≤ 255
Operands:
Operation:
k→W
0 ≤ f ≤ 255
a ∈ [0,1]
Status Affected:
None
Encoding:
0000
Description:
1110
kkkk
kkkk
The 8-bit literal ‘k’ is loaded into W.
Words:
1
Cycles:
1
Operation:
(W) → f
Status Affected:
None
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 (default).
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
© 2008 Microchip Technology Inc.
=
=
4Fh
FFh
4Fh
4Fh
DS39631E-page 293
PIC18F2420/2520/4420/4520
MULLW
Multiply Literal with W
MULWF
Multiply W with f
Syntax:
MULLW
Syntax:
MULWF
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
(W) x (f) → PRODH:PRODL
Status Affected:
None
k
Operands:
0 ≤ k ≤ 255
Operation:
(W) x k → PRODH:PRODL
Status Affected:
None
Encoding:
0000
Description:
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
After Instruction
W
PRODH
PRODL
=
=
=
E2h
?
?
=
=
=
E2h
ADh
08h
ffff
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 (default).
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
0C4h
Before 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
DS39631E-page 294
=
=
=
=
C4h
B5h
?
?
=
=
=
=
C4h
B5h
8Ah
94h
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
NEGF
Negate f
NOP
No Operation
Syntax:
NEGF
Syntax:
NOP
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
f {,a}
Operands:
None
Operation:
No operation
None
Operation:
(f)+1→f
Status Affected:
Status Affected:
N, OV, C, DC, Z
Encoding:
Encoding:
0110
Description:
110a
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 (default).
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
0000
1111
ffff
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]
© 2008 Microchip Technology Inc.
DS39631E-page 295
PIC18F2420/2520/4420/4520
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:
0000
0101
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.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
POP TOS
value
No
operation
POP
GOTO
NEW
Q1
Q2
Q3
Q4
Decode
PUSH
PC + 2 onto
return stack
No
operation
No
operation
Example:
Before Instruction
TOS
Stack (1 level down)
=
=
0031A2h
014332h
After Instruction
TOS
PC
=
=
014332h
NEW
DS39631E-page 296
0000
Description:
Q Cycle Activity:
Example:
0000
PUSH
Before Instruction
TOS
PC
=
=
345Ah
0124h
After Instruction
PC
TOS
Stack (1 level down)
=
=
=
0126h
0126h
345Ah
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
RCALL
Relative Call
RESET
Reset
Syntax:
RCALL
Syntax:
RESET
n
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:
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
This instruction provides a way to
execute a MCLR Reset in software.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Start
Reset
No
operation
No
operation
Example:
Q Cycle Activity:
0000
Description:
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)
© 2008 Microchip Technology Inc.
DS39631E-page 297
PIC18F2420/2520/4420/4520
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
DS39631E-page 298
kkkk
kkkk
W is loaded with the 8-bit literal ‘k’. The
program counter is loaded from the top
of the stack (the return address). The
high address latch (PCLATH) remains
unchanged.
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
Description:
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
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
RETURN
Return from Subroutine
RLCF
Rotate Left f through Carry
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
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 (default).
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
=
© 2008 Microchip Technology Inc.
RLCF
REG, 0, 0
1110 0110
0
1110 0110
1100 1100
1
DS39631E-page 299
PIC18F2420/2520/4420/4520
RLNCF
Rotate Left f (No Carry)
RRCF
Rotate Right f through Carry
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 (default).
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:
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
=
DS39631E-page 300
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 (default).
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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:
(f<n>) → dest<n – 1>,
(f<0>) → dest<7>
FFh → f
Operation:
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, overriding the BSR value. If ‘a’
is ‘1’, then the bank will be selected as
per the BSR value (default).
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 (default).
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
W
REG
=
=
?
1101 0111
1110 1011
1101 0111
© 2008 Microchip Technology Inc.
DS39631E-page 301
PIC18F2420/2520/4420/4520
SLEEP
Enter Sleep mode
SUBFWB
Subtract f from W with Borrow
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
No
operation
Process
Data
Go to
Sleep
Example:
SLEEP
Before Instruction
TO =
?
?
PD =
After Instruction
1†
TO =
0
PD =
† If WDT causes wake-up, this bit is cleared.
DS39631E-page 302
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 (default).
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 {,d {,a}}
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
Example 2:
SUBFWB
REG, 0, 0
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
SUBLW
Subtract W from Literal
SUBWF
Subtract W from f
Syntax:
SUBLW k
Syntax:
SUBWF
Operands:
0 ≤ k ≤ 255
Operands:
Operation:
k – (W) → W
Status Affected:
N, OV, C, DC, Z
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) – (W) → dest
Status Affected:
N, OV, C, DC, Z
Encoding:
0000
1000
kkkk
kkkk
Description
W is subtracted from the 8-bit
literal ‘k’. The result is placed in W.
Words:
1
Cycles:
1
Encoding:
0101
Q1
Q2
Q3
Q4
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
02h
1
Cycles:
1
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 (default).
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:
Decode
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
=
© 2008 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
DS39631E-page 303
PIC18F2420/2520/4420/4520
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 (default).
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 1011)
(0000 1101)
10da
ffff
ffff
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 (default).
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
Description:
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:
=
=
=
=
DS39631E-page 304
; result is zero
REG, 1, 0
03h
0Eh
1
(0000 0011)
(0000 1101)
F5h
(1111 0100)
; [2’s comp]
(0000 1101)
0Eh
0
0
1
; result is negative
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
Before Instruction
TABLAT
TBLPTR
MEMORY (00A356h)
After Instruction
TABLAT
TBLPTR
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:
*+ ;
=
=
=
=
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)
© 2008 Microchip Technology Inc.
DS39631E-page 305
PIC18F2420/2520/4420/4520
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
(Write to
(Read
Holding
TABLAT)
Register )
DS39631E-page 306
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TSTFSZ
Test f, Skip if 0
XORLW
Exclusive OR Literal with W
Syntax:
TSTFSZ f {,a}
Syntax:
XORLW k
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
0 ≤ k ≤ 255
Operation:
(W) .XOR. k → W
Status Affected:
N, Z
Operation:
skip if f = 0
Status Affected:
None
Encoding:
Encoding:
0110
Description:
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 (default).
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)
© 2008 Microchip Technology Inc.
DS39631E-page 307
PIC18F2420/2520/4420/4520
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 (default).
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
=
DS39631E-page 308
REG, 1, 0
AFh
B5h
1Ah
B5h
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
24.2
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
(page 268) apply to both the standard and extended
PIC18 instruction sets.
Extended Instruction Set
In addition to the standard 75 instructions of the PIC18
instruction set, PIC18F2420/2520/4420/4520 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
© 2008 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
DS39631E-page 309
PIC18F2420/2520/4420/4520
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).
DS39631E-page 310
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
© 2008 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
DS39631E-page 311
PIC18F2420/2520/4420/4520
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
Q Cycle Activity:
Q1
Decode
Decode
Q2
Q3
Determine
Determine
source addr source addr
Determine
dest addr
Example:
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
Q4
Read
source reg
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
DS39631E-page 312
Determine
dest addr
Store Literal at FSR2, Decrement FSR2
=
80h
=
33h
=
11h
=
80h
=
33h
=
33h
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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:
© 2008 Microchip Technology Inc.
SUBULNK 23h
Before Instruction
FSR2
=
PC
=
03FFh
0100h
After Instruction
FSR2
=
PC
=
03DCh
(TOS)
DS39631E-page 313
PIC18F2420/2520/4420/4520
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”).
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.
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.
DS39631E-page 314
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.
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.
When porting an application to the PIC18F2420/2520/
4420/4520, 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.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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
© 2008 Microchip Technology Inc.
[OFST]
=
=
2Ch
0A00h
=
00h
=
FFh
DS39631E-page 315
PIC18F2420/2520/4420/4520
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 PIC18F2420/2520/4420/4520 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.
DS39631E-page 316
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.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
25.0
DEVELOPMENT SUPPORT
The PIC® microcontrollers are supported with a full
range of hardware and software development tools:
• Integrated Development Environment
- MPLAB® IDE Software
• Assemblers/Compilers/Linkers
- MPASMTM Assembler
- MPLAB C18 and MPLAB C30 C Compilers
- MPLINKTM Object Linker/
MPLIBTM Object Librarian
- MPLAB ASM30 Assembler/Linker/Library
• Simulators
- MPLAB SIM Software Simulator
• Emulators
- MPLAB ICE 2000 In-Circuit Emulator
- MPLAB REAL ICE™ In-Circuit Emulator
• In-Circuit Debugger
- MPLAB ICD 2
• Device Programmers
- PICSTART® Plus Development Programmer
- MPLAB PM3 Device Programmer
- PICkit™ 2 Development Programmer
• Low-Cost Demonstration and Development
Boards and Evaluation Kits
25.1
MPLAB Integrated Development
Environment Software
The MPLAB IDE software brings an ease of software
development previously unseen in the 8/16-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)
- 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
• Visual device initializer for easy register
initialization
• 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
HI-TECH Software C Compilers and IAR
C Compilers
The MPLAB IDE allows you to:
• Edit your source files (either assembly or C)
• One touch assemble (or compile) and download
to PIC MCU emulator and simulator tools
(automatically updates all project information)
• Debug using:
- Source files (assembly or C)
- Mixed assembly and C
- 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.
© 2008 Microchip Technology Inc.
DS39631E-page 317
PIC18F2420/2520/4420/4520
25.2
MPASM Assembler
The MPASM Assembler is a full-featured, universal
macro assembler for all PIC 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:
• 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
25.5
MPLAB ASM30 Assembler produces relocatable
machine code from symbolic assembly language for
dsPIC30F devices. MPLAB C30 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 dsPIC30F instruction set
Support for fixed-point and floating-point data
Command line interface
Rich directive set
Flexible macro language
MPLAB IDE compatibility
25.6
25.3
MPLAB C18 and MPLAB C30
C Compilers
The MPLAB C18 and MPLAB C30 Code Development
Systems are complete ANSI C compilers for
Microchip’s PIC18 and PIC24 families of microcontrollers and the dsPIC30 and dsPIC33 family of digital
signal controllers. These compilers provide powerful
integration capabilities, superior code optimization and
ease of use not found with other compilers.
For easy source level debugging, the compilers provide
symbol information that is optimized to the MPLAB IDE
debugger.
25.4
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.
MPLAB ASM30 Assembler, Linker
and Librarian
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 C18 and
MPLAB C30 C Compilers, and the MPASM and
MPLAB ASM30 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.
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
DS39631E-page 318
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
25.7
MPLAB ICE 2000
High-Performance
In-Circuit Emulator
The MPLAB ICE 2000 In-Circuit Emulator is intended
to provide the product development engineer with a
complete microcontroller design tool set for PIC
microcontrollers. Software control of the MPLAB ICE
2000 In-Circuit Emulator is advanced by the MPLAB
Integrated Development Environment, which allows
editing, building, downloading and source debugging
from a single environment.
The MPLAB ICE 2000 is a full-featured emulator
system with enhanced trace, trigger and data monitoring features. Interchangeable processor modules allow
the system to be easily reconfigured for emulation of
different processors. The architecture of the MPLAB
ICE 2000 In-Circuit Emulator allows expansion to
support new PIC microcontrollers.
The MPLAB ICE 2000 In-Circuit Emulator system has
been designed as a real-time emulation system with
advanced features that are typically found on more
expensive development tools. The PC platform and
Microsoft® Windows® 32-bit operating system were
chosen to best make these features available in a
simple, unified application.
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 MPLAB REAL ICE probe 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 the popular MPLAB ICD 2 system
(RJ11) or with the new high-speed, noise tolerant, LowVoltage Differential Signal (LVDS) interconnection
(CAT5).
25.9
MPLAB ICD 2 In-Circuit Debugger
Microchip’s In-Circuit Debugger, MPLAB ICD 2, is a
powerful, low-cost, run-time development tool,
connecting to the host PC via an RS-232 or high-speed
USB interface. This tool is based on the Flash PIC
MCUs and can be used to develop for these and other
PIC MCUs and dsPIC DSCs. The MPLAB ICD 2 utilizes
the in-circuit debugging capability built into the Flash
devices. This feature, along with Microchip’s In-Circuit
Serial ProgrammingTM (ICSPTM) protocol, offers costeffective, in-circuit Flash debugging from the graphical
user interface of the MPLAB Integrated Development
Environment. This enables a designer to develop and
debug source code by setting breakpoints, single stepping and watching variables, and CPU status and
peripheral registers. Running at full speed enables
testing hardware and applications in real time. MPLAB
ICD 2 also serves as a development programmer for
selected PIC devices.
25.10 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 SD/MMC card for
file storage and secure data applications.
MPLAB REAL ICE is field upgradeable through future
firmware downloads in MPLAB IDE. In upcoming
releases of MPLAB IDE, new devices will be supported,
and new features will be added, such as software breakpoints and assembly code trace. MPLAB REAL ICE
offers significant advantages over competitive emulators
including low-cost, full-speed emulation, real-time
variable watches, trace analysis, complex breakpoints, a
ruggedized probe interface and long (up to three meters)
interconnection cables.
© 2008 Microchip Technology Inc.
DS39631E-page 319
PIC18F2420/2520/4420/4520
25.11 PICSTART Plus Development
Programmer
25.13 Demonstration, Development and
Evaluation Boards
The PICSTART Plus Development Programmer is an
easy-to-use, low-cost, prototype programmer. It
connects to the PC via a COM (RS-232) port. MPLAB
Integrated Development Environment software makes
using the programmer simple and efficient. The
PICSTART Plus Development Programmer supports
most PIC devices in DIP packages up to 40 pins.
Larger pin count devices, such as the PIC16C92X and
PIC17C76X, may be supported with an adapter socket.
The PICSTART Plus Development Programmer is CE
compliant.
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.
25.12 PICkit 2 Development Programmer
The PICkit™ 2 Development Programmer is a low-cost
programmer and selected Flash device debugger with
an easy-to-use interface for programming many of
Microchip’s baseline, mid-range and PIC18F families of
Flash memory microcontrollers. The PICkit 2 Starter Kit
includes a prototyping development board, twelve
sequential lessons, software and HI-TECH’s PICC™
Lite C compiler, and is designed to help get up to speed
quickly using PIC® microcontrollers. The kit provides
everything needed to program, evaluate and develop
applications using Microchip’s powerful, mid-range
Flash memory family of microcontrollers.
DS39631E-page 320
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.
Check the Microchip web page (www.microchip.com)
for the complete list of demonstration, development
and evaluation kits.
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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 +7.5V
Voltage on MCLR with respect to VSS (Note 2) ......................................................................................... 0V to +13.25V
Total power dissipation (Note 1) ...............................................................................................................................1.0W
Maximum current out of VSS pin ...........................................................................................................................300 mA
Maximum current into VDD pin ..............................................................................................................................250 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 .......................................................................................................................200 mA
Maximum current sourced by all ports ..................................................................................................................200 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 50-100Ω 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.
© 2008 Microchip Technology Inc.
DS39631E-page 321
PIC18F2420/2520/4420/4520
FIGURE 26-1:
PIC18F2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V
5.5V
Voltage
5.0V
PIC18F2420/2520/4420/4520
4.5V
4.2V
4.0V
3.5V
3.0V
2.5V
2.0V
40 MHz
Frequency
FIGURE 26-2:
PIC18F2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (EXTENDED)
6.0V
5.5V
Voltage
5.0V
PIC18F2420/2520/4420/4520
4.5V
4.2V
4.0V
3.5V
3.0V
2.5V
2.0V
25 MHz
Frequency
DS39631E-page 322
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-3:
PIC18LF2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V
5.5V
Voltage
5.0V
4.5V
PIC18LF2420/2520/4420/4520
4.2V
4.0V
3.5V
3.0V
2.5V
2.0V
40 MHz
4 MHz
Frequency
FMAX = (16.36 MHz/V) (VDDAPPMIN – 2.0V) + 4 MHz
Note: VDDAPPMIN is the minimum voltage of the PIC® device in the application.
© 2008 Microchip Technology Inc.
DS39631E-page 323
PIC18F2420/2520/4420/4520
26.1
DC Characteristics:
Supply Voltage
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
D001
Symbol
VDD
Characteristic
Min
Typ
Max Units
Conditions
Supply Voltage
PIC18LF2X2X/4X20 2.0
—
5.5
V
HS, XT, RC and LP Oscillator mode
PIC18F2X20/4X20 4.2
—
5.5
V
D002
VDR
RAM Data Retention
1.5
—
—
V
Voltage(1)
VDD Start Voltage
—
—
0.7
V
See section on Power-on Reset for details
D003
VPOR
to Ensure Internal
Power-on Reset Signal
D004
SVDD
VDD Rise Rate
0.05
—
— V/ms See section on Power-on Reset for details
to Ensure Internal
Power-on Reset Signal
VBOR
Brown-out Reset Voltage
D005
PIC18LF2X2X/4X20
BORV<1:0> = 11
2.00 2.11 2.22
V
BORV<1:0> = 10
2.65 2.79 2.93
V
D005
All Devices
BORV<1:0> = 01(2)
4.11 4.33 4.55
V
BORV<1:0> = 00
4.36 4.59 4.82
V
Legend: Shading of rows is to assist in readability of the table.
Note 1: This is the limit to which VDD can be lowered in Sleep mode, or during a device Reset, without losing RAM data.
2: With BOR enabled, full-speed operation (FOSC = 40 MHz) is supported until a BOR occurs. This is valid although
VDD may be below the minimum voltage for this frequency.
DS39631E-page 324
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Typ
Max
Units
Power-Down Current (IPD)(1)
PIC18LF2X2X/4X20 0.1
0.1
0.5
0.5
μA
μA
-40°C
+25°C
0.2
0.1
0.1
0.3
0.1
2.5
0.7
0.7
3.5
1.0
μA
μA
μA
μA
μA
+85°C
-40°C
+25°C
+85°C
-40°C
PIC18LF2X2X/4X20
All devices
Legend:
Note 1:
2:
3:
4:
Conditions
VDD = 2.0V
(Sleep mode)
VDD = 3.0V
(Sleep mode)
0.2
1.0
μA
+25°C
VDD = 5.0V
(Sleep mode)
0.7
10
μA
+85°C
Extended devices only 10
100
μA
+125°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
© 2008 Microchip Technology Inc.
DS39631E-page 325
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Typ
Max
Units
13
13
14
42
34
28
103
82
67
71
320
25
22
25
61
46
45
160
130
120
230
440
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
Conditions
Supply Current (IDD)(2)
PIC18LF2X2X/4X20
PIC18LF2X2X/4X20
All devices
Extended devices only
PIC18LF2X2X/4X20
Legend:
Note 1:
2:
3:
4:
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
-40°C
VDD = 2.0V
VDD = 3.0V
FOSC = 31 kHz
(RC_RUN mode,
INTRC source)
VDD = 5.0V
VDD = 2.0V
330
440
μA
+25°C
330
440
μA
+85°C
PIC18LF2X2X/4X20 630
800
μA
-40°C
FOSC = 1 MHz
590
720
μA
+25°C
VDD = 3.0V
(RC_RUN mode,
570
700
μA
+85°C
INTOSC source)
All devices 1.2
1.6
mA
-40°C
1.0
1.5
mA
+25°C
VDD = 5.0V
1.0
1.5
mA
+85°C
Extended devices only 1.0
1.5
mA
+125°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
DS39631E-page 326
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Typ
Max
Units
Conditions
Supply Current (IDD)(2)
PIC18LF2X2X/4X20
Legend:
Note 1:
2:
3:
4:
0.8
1.1
mA
-40°C
0.8
1.1
mA
+25°C
VDD = 2.0V
0.8
1.1
mA
+85°C
PIC18LF2X2X/4X20 1.3
1.7
mA
-40°C
FOSC = 4 MHz
VDD = 3.0V
1.3
1.7
mA
+25°C
(RC_RUN mode,
1.3
1.7
mA
+85°C
INTOSC source)
All devices 2.5
3.5
mA
-40°C
2.5
3.5
mA
+25°C
VDD = 5.0V
2.5
3.5
mA
+85°C
Extended devices only 2.5
3.5
mA
+125°C
PIC18LF2X2X/4X20 2.9
5
μA
-40°C
VDD = 2.0V
3.1
5
μA
+25°C
3.6
9.5
μA
+85°C
PIC18LF2X2X/4X20 4.5
8
μA
-40°C
FOSC = 31 kHz
4.8
8
μA
+25°C
VDD = 3.0V
(RC_IDLE mode,
5.8
15
μA
+85°C
INTRC source)
All devices 9.2
16
μA
-40°C
9.8
16
μA
+25°C
VDD = 5.0V
11.0
35
μA
+85°C
Extended devices only 21
160
μA
+125°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
© 2008 Microchip Technology Inc.
DS39631E-page 327
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Supply Current (IDD)(2)
PIC18LF2X2X/4X20
PIC18LF2X2X/4X20
All devices
Extended devices only
PIC18LF2X2X/4X20
PIC18LF2X2X/4X20
All devices
Extended devices only
Legend:
Note 1:
2:
3:
4:
Typ
Max
Units
165
175
190
250
270
290
500
520
550
0.6
340
350
360
520
540
580
1.0
1.1
1.1
1.1
250
250
270
360
360
380
700
700
700
1
500
500
500
800
800
850
1.6
1.4
1.4
2.0
μA
μA
μA
μA
μA
μA
μA
μA
μA
mA
μA
μA
μA
μA
μA
μA
mA
mA
mA
mA
Conditions
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
VDD = 2.0V
VDD = 3.0V
FOSC = 1 MHz
(RC_IDLE mode,
INTOSC source)
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
FOSC = 4 MHz
(RC_IDLE mode,
INTOSC source)
VDD = 5.0V
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
DS39631E-page 328
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Typ
Max
Units
Conditions
250
260
250
550
480
460
1.2
1.1
1.0
1.0
0.72
350
350
350
650
640
600
1.5
1.4
1.3
3.0
1.0
μA
μA
μA
μA
μA
μA
mA
mA
mA
mA
mA
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
-40°C
0.74
0.74
1.3
1.3
1.3
2.7
2.6
2.5
2.6
8.4
11
1.0
1.0
1.8
1.8
1.8
4.0
4.0
4.0
5.0
13
16
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
+125°C
+125°C
Supply Current (IDD)(2)
PIC18LF2X2X/4X20
PIC18LF2X2X/4X20
All devices
Extended devices only
PIC18LF2X2X/4X20
PIC18LF2X2X/4X20
All devices
Extended devices only
Extended devices only
VDD = 2.0V
VDD = 3.0V
FOSC = 1 MHZ
(PRI_RUN,
EC oscillator)
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
FOSC = 4 MHz
(PRI_RUN,
EC oscillator)
VDD = 5.0V
VDD = 4.2V
VDD = 5.0V
FOSC = 25 MHz
(PRI_RUN,
EC oscillator)
All devices
Legend:
Note 1:
2:
3:
4:
15
20
mA
-40°C
VDD = 4.2V
15
20
mA
+25°C
FOSC = 40 MHZ
15
20
mA
+85°C
(PRI_RUN,
All devices 20
25
mA
-40°C
EC oscillator)
20
25
mA
+25°C
VDD = 5.0V
20
25
mA
+85°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
© 2008 Microchip Technology Inc.
DS39631E-page 329
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Typ
Max
Units
7.5
7.4
7.3
8.0
10
10
10
10
12
12
mA
mA
mA
mA
mA
Conditions
Supply Current (IDD)(2)
All devices
Extended devices only
All devices
Legend:
Note 1:
2:
3:
4:
-40°C
+25°C
+85°C
+125°C
-40°C
VDD = 4.2V
FOSC = 4 MHZ,
16 MHz internal
(PRI_RUN HS+PLL)
FOSC = 4 MHZ,
10
12
mA
+25°C
16 MHz internal
VDD = 5.0V
9.7
12
mA
+85°C
(PRI_RUN HS+PLL)
Extended devices only 10
14
mA
+125°C
All devices 15
20
mA
-40°C
FOSC = 10 MHZ,
VDD = 4.2V
15
20
mA
+25°C
40 MHz internal
(PRI_RUN
HS+PLL)
15
20
mA
+85°C
All devices 20
25
mA
-40°C
FOSC = 10 MHZ,
20
25
mA
+25°C
40 MHz internal
VDD = 5.0V
(PRI_RUN HS+PLL)
20
25
mA
+85°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
DS39631E-page 330
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Typ
Max
Supply Current (IDD)(2)
PIC18LF2X2X/4X20
65
100
μA
-40°C
65
70
120
120
130
230
235
240
260
260
255
270
420
430
450
0.9
0.9
0.9
1
2.8
4.3
100
110
140
140
160
300
300
300
500
360
360
360
620
620
650
1.2
1.2
1.2
1.3
6.0
8.0
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
mA
mA
mA
mA
mA
mA
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
+125°C
+125°C
6.0
6.2
6.6
8.1
10
10
10
13
mA
mA
mA
mA
-40°C
+25°C
+85°C
-40°C
PIC18LF2X2X/4X20
All devices
Extended devices only
PIC18LF2X2X/4X20
PIC18LF2X2X/4X20
All devices
Extended devices only
Extended devices only
All devices
All devices
Legend:
Note 1:
2:
3:
4:
Units
Conditions
VDD = 2.0V
VDD = 3.0V
FOSC = 1 MHz
(PRI_IDLE mode,
EC oscillator)
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
FOSC = 4 MHz
(PRI_IDLE mode,
EC oscillator)
VDD = 5.0V
VDD = 4.2V
VDD = 5.0V
VDD = 4.2V
FOSC = 25 MHz
(PRI_IDLE mode,
EC oscillator)
FOSC = 40 MHz
(PRI_IDLE mode,
EC oscillator)
VDD = 5.0V
9.1
12
mA
+25°C
8.3
12
mA
+85°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
© 2008 Microchip Technology Inc.
DS39631E-page 331
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Supply Current (IDD)(2)
PIC18LF2X2X/4X20
Legend:
Note 1:
2:
3:
4:
Typ
Max
Units
10
11
25
21
μA
μA
Conditions
-40°C(3)
+25°C
VDD = 2.0V
12
25
μA
+85°C
PIC18LF2X2X/4X20 42
57
μA
-40°C(3)
FOSC = 32 kHz(3)
33
45
μA
+25°C
VDD = 3.0V
(SEC_RUN mode,
Timer1 as clock)
29
45
μA
+85°C
(3)
All devices 105
150
μA
-40°C
81
130
μA
+25°C
VDD = 5.0V
67
130
μA
+85°C
PIC18LF2X2X/4X20 3.0
12
μA
-40°C(3)
3.0
6
μA
+25°C
VDD = 2.0V
3.7
10
μA
+85°C
PIC18LF2X2X/4X20 5.0
15
μA
-40°C(3)
FOSC = 32 kHz(3)
5.4
10
μA
+25°C
VDD = 3.0V
(SEC_IDLE mode,
Timer1 as clock)
6.3
15
μA
+85°C
(3)
All devices 8.5
25
μA
-40°C
9.0
20
μA
+25°C
VDD = 5.0V
10.5
30
μA
+85°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
DS39631E-page 332
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
Typ
Max
Units
Conditions
Module Differential Currents (ΔIWDT, ΔIBOR, ΔILVD, ΔIOSCB, ΔIAD)
A/D Converter 0.2
1.0
μA
-40°C to +85°C
0.2
1.0
μA
-40°C to +85°C
0.2
1.0
μA
-40°C to +85°C
D026
(ΔIAD)
D022
(ΔIWDT)
D022A
(ΔIBOR)
D022B
(ΔILVD)
Legend:
Note 1:
2:
3:
4:
Watchdog Timer
0.5
1.3
1.4
1.6
1.9
4.0
2.2
2.2
2.3
3.5
μA
μA
μA
μA
μA
-40°C to +125°C
-40°C
+25°C
+85°C
-40°C
2.0
2.2
3.0
3.5
3.5
4.0
3.5
3.5
7.5
7.5
7.8
10
μA
μA
μA
μA
μA
μA
+25°C
+85°C
-40°C
+25°C
+85°C
+125°C
VDD = 2.0V
VDD = 3.0V
A/D on, not converting
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
Brown-out Reset(4)
35
50
μA
-40°C to +85°C
VDD = 3.0V
40
55
μA
-40°C to +85°C
55
65
μA -40°C to +125°C
VDD = 5.0V
0
2
μA
-40°C to +85°C
Sleep mode,
BOREN<1:0> = 10
0
5
μA -40°C to +125°C
38
μA
-40°C to +85°C
VDD = 2.0V
High/Low-Voltage 22
Detect(4) 25
40
μA
-40°C to +85°C
VDD = 3.0V
29
45
μA
-40°C to +85°C
VDD = 5.0V
30
45
μA -40°C to +125°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
© 2008 Microchip Technology Inc.
DS39631E-page 333
PIC18F2420/2520/4420/4520
26.2
DC Characteristics:
Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
Param
No.
Device
D025L
(ΔIOSCB)
Legend:
Note 1:
2:
3:
4:
Timer1 Oscillator
Typ
Max
Units
4.5
0.9
0.9
9.0
1.6
1.6
μA
μA
μA
Conditions
-40°C(3)
-10°C
+25°C
VDD = 2.0V
32 kHz on Timer1
0.9
1.8
μA
+85°C
4.8
10
μA
-40°C(3)
1.0
2.0
μA
-10°C
VDD = 3.0V
32 kHz on Timer1
1.0
2.0
μA
+25°C
1.0
2.6
μA
+85°C
6.0
11
μA
-40°C(3)
1.6
4.0
μA
-10°C
VDD = 5.0V
32 kHz on Timer1
1.6
4.0
μA
+25°C
1.6
4.0
μA
+85°C
Shading of rows is to assist in readability of the table.
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.).
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:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS;
MCLR = VDD; WDT enabled/disabled as specified.
When operation below -10°C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
When operation will always be above -10°C, then the low-power Timer1 oscillator may be selected.
BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less
than the sum of both specifications.
DS39631E-page 334
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.3
DC Characteristics: PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
DC CHARACTERISTICS
Param
Symbol
No.
VIL
Characteristic
Min
Max
Units
Conditions
VSS
0.15 VDD
V
VDD < 4.5V
—
0.8
V
4.5V ≤ VDD ≤ 5.5V
VSS
0.2 VDD
V
VSS
0.3 VDD
V
I2C™ enabled
SMBus enabled
Input Low Voltage
I/O Ports:
D030
with TTL Buffer
D030A
D031
with Schmitt Trigger Buffer
D031A
RC3 and RC4
VSS
0.8
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
0.3
V
V
V
RC, EC modes(1)
XT, LP modes
0.25 VDD + 0.8V
VDD
V
VDD < 4.5V
2.0
VDD
V
4.5V ≤ VDD ≤ 5.5V
0.8 VDD
VDD
V
0.7 VDD
VDD
V
I2C enabled
2.1
VDD
V
SMBus enabled
VDD
V
D031B
VIH
Input High Voltage
I/O Ports:
D040
with TTL Buffer
D040A
D041
with Schmitt Trigger Buffer
D041A
RC3 and RC4
D041B
D042
MCLR
0.8 VDD
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
—
±200
nA
±50
nA
VDD < 5.5V,
VSS ≤ VPIN ≤ VDD,
Pin at high-impedance
VDD < 3V,
VSS ≤ VPIN ≤ VDD,
Pin at high-impedance
IIL
D060
Input Leakage Current(2,3)
I/O Ports
D061
D063
D070
Note 1:
2:
3:
MCLR
—
±1
μA
Vss ≤ VPIN ≤ VDD
OSC1
—
±1
μA
Vss ≤ VPIN ≤ VDD
50
400
μA
VDD = 5V, VPIN = VSS
IPU
Weak Pull-up Current
IPURB
PORTB Weak Pull-up Current
In RC oscillator configuration, the OSC1/CLKI 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.
© 2008 Microchip Technology Inc.
DS39631E-page 335
PIC18F2420/2520/4420/4520
26.3
DC Characteristics: PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
DC CHARACTERISTICS
Param
Symbol
No.
VOL
Characteristic
Min
Max
Units
Conditions
Output Low Voltage
D080
I/O Ports
—
0.6
V
IOL = 8.5 mA, VDD = 4.5V,
-40°C to +85°C
D083
OSC2/CLKO
(RC, RCIO, EC, ECIO modes)
—
0.6
V
IOL = 1.6 mA, VDD = 4.5V,
-40°C to +85°C
VOH
Output High Voltage(3)
D090
I/O Ports
VDD – 0.7
—
V
IOH = -3.0 mA, VDD = 4.5V,
-40°C to +85°C
D092
OSC2/CLKO
(RC, RCIO, EC, ECIO modes)
VDD – 0.7
—
V
IOH = -1.3 mA, VDD = 4.5V,
-40°C to +85°C
—
15
pF
In XT, HS and LP modes
when external clock is
used to drive OSC1
Capacitive Loading Specs
on Output Pins
D100
COSC2 OSC2 pin
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:
In RC oscillator configuration, the OSC1/CLKI 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.
DS39631E-page 336
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 26-1:
MEMORY PROGRAMMING REQUIREMENTS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
DC CHARACTERISTICS
Param
No.
Sym
Characteristic
Min
Typ†
Max
Units
Conditions
Data EEPROM Memory
D120
ED
Byte Endurance
100K
1M
—
D121
VDRW
VDD for Read/Write
VMIN
—
5.5
E/W -40°C to +85°C
V
D122
TDEW
Erase/Write Cycle Time
—
4
—
ms
D123
TRETD Characteristic Retention
40
—
—
Year Provided no other
specifications are violated
D124
TREF
Number of Total Erase/Write
Cycles before Refresh(1)
1M
10M
—
E/W -40°C to +85°C
D125
IDDP
Supply Current during
Programming
—
10
—
mA
E/W -40°C to +85°C
Using EECON to read/write
VMIN = Minimum operating
voltage
Program Flash Memory
D130
EP
Cell Endurance
10K
100K
—
D131
VPR
VDD for Read
VMIN
—
5.5
V
D132
VIE
VDD for Block Erase
3.0
—
5.5
V
Using ICSP™ port, +25°C
D132A VIW
VDD for Externally Timed Erase
or Write
4.5
—
5.5
V
Using ICSP™ port, +25°C
D132B VPEW
VDD for Self-Timed Write
VMIN
—
5.5
V
VMIN = Minimum operating
voltage
D133
ICSP Block Erase Cycle Time
—
4
—
ms
VDD ≥ 4.5V
D133A TIW
ICSP Erase or Write Cycle Time
(externally timed)
1
—
—
ms
VDD ≥ 4.5V, +25°C
D133A TIW
Self-Timed Write Cycle Time
—
2
—
ms
40
100
—
Year Provided no other
specifications are violated
—
10
—
mA
TIE
D134
TRETD Characteristic Retention
D135
IDDP
Supply Current during
Programming
VMIN = Minimum operating
voltage
† Data in “Typ” column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested.
Note 1: Refer to Section 7.8 “Using the Data EEPROM” for a more detailed discussion on data EEPROM
endurance.
© 2008 Microchip Technology Inc.
DS39631E-page 337
PIC18F2420/2520/4420/4520
TABLE 26-2:
COMPARATOR SPECIFICATIONS
Operating Conditions: 3.0V < VDD < 5.5V, -40°C < TA < +85°C (unless otherwise stated).
Param
No.
Sym
Characteristics
Min
Typ
Max
Units
Comments
D300
VIOFF
Input Offset Voltage
—
±5.0
±10
mV
D301
VICM
Input Common Mode Voltage
0
—
VDD – 1.5
V
D302
CMRR
Common Mode Rejection Ratio
55
—
—
dB
300
TRESP
Response Time(1)
—
150
400
ns
PIC18FXXXX
—
150
600
ns
PIC18LFXXXX,
VDD = 2.0V
—
—
10
μs
300A
301
Note 1:
TMC2OV
Comparator Mode Change to
Output Valid
Response time measured with one comparator input at (VDD – 1.5)/2, while the other input transitions
from VSS to VDD.
TABLE 26-3:
VOLTAGE REFERENCE SPECIFICATIONS
Operating Conditions: 3.0V < VDD < 5.5V, -40°C < TA < +85°C (unless otherwise stated).
Param
No.
Sym
Characteristics
Min
Typ
Max
Units
VDD/24
—
VDD/32
LSb
VRES
Resolution
D311
VRAA
Absolute Accuracy
—
—
1/2
LSb
D312
VRUR
Unit Resistor Value (R)
—
2k
—
Ω
TSET
Time(1)
—
—
10
μs
D310
310
Note 1:
Settling
Comments
Settling time measured while CVRR = 1 and CVR3:CVR0 transitions from ‘0000’ to ‘1111’.
DS39631E-page 338
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-4:
HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
VDD
(HLVDIF can be
cleared in software)
VLVD
(HLVDIF set by hardware)
HLVDIF(1)
Note 1: VDIRMAG = 0.
TABLE 26-4:
HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
Param
Sym
No.
D420
Characteristic
Min
Typ
Max
Units
HLVD Voltage on VDD HLVDL<3:0> = 0000
Transition High-to-Low HLVDL<3:0> = 0001
2.06
2.17
2.28
V
2.12
2.23
2.34
V
HLVDL<3:0> = 0010
2.24
2.36
2.48
V
HLVDL<3:0> = 0011
2.32
2.44
2.56
V
HLVDL<3:0> = 0100
2.47
2.60
2.73
V
HLVDL<3:0> = 0101
2.65
2.79
2.93
V
HLVDL<3:0> = 0110
2.74
2.89
3.04
V
HLVDL<3:0> = 0111
2.96
3.12
3.28
V
HLVDL<3:0> = 1000
3.22
3.39
3.56
V
HLVDL<3:0> = 1001
3.37
3.55
3.73
V
HLVDL<3:0> = 1010
3.52
3.71
3.90
V
HLVDL<3:0> = 1011
3.70
3.90
4.10
V
HLVDL<3:0> = 1100
3.90
4.11
4.32
V
HLVDL<3:0> = 1101
4.11
4.33
4.55
V
HLVDL<3:0> = 1110
4.36
4.59
4.82
V
© 2008 Microchip Technology Inc.
Conditions
DS39631E-page 339
PIC18F2420/2520/4420/4520
26.4
26.4.1
AC (Timing) Characteristics
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
CLKO
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
2
TCC:ST (I C specifications only)
CC
HD
Hold
ST
DAT
DATA input hold
STA
Start condition
DS39631E-page 340
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
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.4.2
TIMING CONDITIONS
Note:
The temperature and voltages specified in Table 26-5
apply to all timing specifications unless otherwise
noted. Figure 26-5 specifies the load conditions for the
timing specifications.
TABLE 26-5:
TEMPERATURE AND VOLTAGE SPECIFICATIONS – AC
AC CHARACTERISTICS
FIGURE 26-5:
Because of space limitations, the generic
terms “PIC18FXXXX” and “PIC18LFXXXX”
are used throughout this section to refer to
the PIC18F2420/2520/4420/4520 and
PIC18LF2420/2520/4420/4520 families of
devices specifically and only those devices.
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Operating voltage VDD range as described in DC specification Section 26.1 and
Section 26.3.
LF parts operate for industrial temperatures only.
LOAD CONDITIONS FOR DEVICE TIMING SPECIFICATIONS
Load Condition 2
Load Condition 1
VDD/2
RL
CL
Pin
VSS
CL
Pin
RL = 464Ω
VSS
© 2008 Microchip Technology Inc.
CL = 50 pF
for all pins except OSC2/CLKO
and including D and E outputs as ports
DS39631E-page 341
PIC18F2420/2520/4420/4520
26.4.3
TIMING DIAGRAMS AND SPECIFICATIONS
FIGURE 26-6:
EXTERNAL CLOCK TIMING (ALL MODES EXCEPT PLL)
Q4
Q1
Q2
Q3
Q4
Q1
OSC1
1
3
4
3
4
2
CLKO
TABLE 26-6:
Param.
No.
1A
EXTERNAL CLOCK TIMING REQUIREMENTS
Symbol
FOSC
Characteristic
Min
Max
Units
External CLKI Frequency(1)
DC
1
MHz
XT, RC Oscillator mode
DC
25
MHz
HS Oscillator mode
DC
31.25
kHz
LP Oscillator mode
DC
40
MHz
EC Oscillator mode
DC
4
MHz
RC Oscillator mode
0.1
4
MHz
XT Oscillator mode
4
25
MHz
HS Oscillator mode
4
10
MHz
HS + PLL Oscillator mode
LP Oscillator mode
Oscillator Frequency
1
TOSC
(1)
External CLKI Period(1)
Oscillator Period(1)
2
3
4
Note 1:
TCY
Instruction Cycle
Time(1)
TOSL,
TOSH
External Clock in (OSC1)
High or Low Time
TOSR,
TOSF
External Clock in (OSC1)
Rise or Fall Time
Conditions
5
200
kHz
1000
—
ns
XT, RC Oscillator mode
40
—
ns
HS Oscillator mode
32
—
μs
LP Oscillator mode
25
—
ns
EC Oscillator mode
250
—
ns
RC Oscillator mode
0.25
10
μs
XT Oscillator mode
40
250
ns
HS Oscillator mode
100
250
ns
HS + PLL Oscillator mode
5
200
μs
LP Oscillator mode
100
—
ns
TCY = 4/FOSC, Industrial
160
—
ns
TCY = 4/FOSC, Extended
30
—
ns
XT Oscillator mode
2.5
—
μs
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/CLKI pin. When an external clock
input is used, the “max.” cycle time limit is “DC” (no clock) for all devices.
DS39631E-page 342
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 26-7:
Param
No.
PLL CLOCK TIMING SPECIFICATIONS (VDD = 4.2V TO 5.5V)
Sym
Characteristic
Min
Typ†
Max
4
16
—
—
10
40
Units
F10
F11
FOSC Oscillator Frequency Range
FSYS On-Chip VCO System Frequency
F12
trc
PLL Start-up Time (Lock Time)
—
—
2
ms
ΔCLK
CLKO Stability (Jitter)
-2
—
+2
%
F13
Conditions
MHz HS mode only
MHz HS mode only
† Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested.
TABLE 26-8:
AC CHARACTERISTICS: INTERNAL RC ACCURACY
PIC18F2420/2520/4420/4520 (INDUSTRIAL)
PIC18LF2420/2520/4420/4520 (INDUSTRIAL)
PIC18LF2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2420/2520/4420/4520
(Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
No.
Device
Min
Typ
Max
Units
Conditions
INTOSC Accuracy @ Freq = 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz, 125 kHz, 31 kHz(1)
PIC18LF2420/2520/4420/4520
-2
+/-1
2
%
-5
+/-1
5
%
-2
+/-1
2
%
-5
+/-1
5
%
-40°C to +85°C VDD = 4.5-5.5V
PIC18LF2420/2520/4420/4520 26.562
—
35.938
kHz
-40°C to +85°C VDD = 2.7-3.3V
PIC18F2420/2520/4420/4520 26.562
—
35.938
kHz
-40°C to +85°C VDD = 4.5-5.5V
PIC18F2420/2520/4420/4520
+25°C
VDD = 2.7-3.3V
-40°C to +85°C VDD = 2.7-3.3V
+25°C
VDD = 4.5-5.5V
INTRC Accuracy @ Freq = 31 kHz
Legend:
Note 1:
Shading of rows is to assist in readability of the table.
Frequency calibrated at 25°C. OSCTUNE register can be used to compensate for temperature drift.
© 2008 Microchip Technology Inc.
DS39631E-page 343
PIC18F2420/2520/4420/4520
FIGURE 26-7:
CLKO AND I/O TIMING
Q1
Q4
Q2
Q3
OSC1
11
10
CLKO
13
14
19
12
18
16
I/O pin
(Input)
15
17
I/O pin
(Output)
Note:
20, 21
Refer to Figure 26-5 for load conditions.
TABLE 26-9:
Param
No.
10
New Value
Old Value
CLKO AND I/O TIMING REQUIREMENTS
Symbol
Characteristic
TosH2ckL OSC1 ↑ to CLKO ↓
Min
Typ
Max
—
75
200
Units Conditions
ns
(Note 1)
11
TosH2ckH OSC1 ↑ to CLKO ↑
—
75
200
ns
(Note 1)
12
TckR
CLKO Rise Time
—
35
100
ns
(Note 1)
13
TckF
CLKO Fall Time
—
35
100
ns
(Note 1)
14
TckL2ioV
CLKO ↓ to Port Out Valid
—
—
0.5 TCY + 20
ns
(Note 1)
15
TioV2ckH Port In Valid before CLKO ↑
16
TckH2ioI
17
TosH2ioV OSC1 ↑ (Q1 cycle) to Port Out Valid
18
TosH2ioI
18A
Port In Hold after CLKO ↑
OSC1 ↑ (Q2 cycle) to
Port Input Invalid
(I/O in hold time)
0.25 TCY + 25
—
—
ns
(Note 1)
0
—
—
ns
(Note 1)
—
50
150
ns
PIC18FXXXX
100
—
—
ns
PIC18LFXXXX
200
—
—
ns
19
TioV2osH Port Input Valid to OSC1 ↑ (I/O in setup
time)
0
—
—
ns
20
TioR
Port Output Rise Time
—
10
25
ns
TioF
Port Output Fall Time
22†
TINP
INTx pin High or Low Time
23†
TRBP
RB<7:4> Change INTx High or Low Time
TCY
20A
21
21A
PIC18FXXXX
PIC18LFXXXX
—
—
60
ns
PIC18FXXXX
—
10
25
ns
—
—
60
ns
TCY
—
—
ns
—
—
ns
PIC18LFXXXX
VDD = 2.0V
VDD = 2.0V
VDD = 2.0V
† These parameters are asynchronous events not related to any internal clock edges.
Note 1: Measurements are taken in RC mode, where CLKO output is 4 x TOSC.
DS39631E-page 344
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-8:
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 26-5 for load conditions.
FIGURE 26-9:
BROWN-OUT RESET TIMING
BVDD
VDD
35
VIRVST
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.
Characteristic
Min
Typ
Max
Units
2
3.4
—
4.1
—
4.71
μs
ms
1024 TOSC
—
1024 TOSC
—
55.6
65.5
75.4
ms
—
2
—
μs
Conditions
30
31
TmcL
TWDT
32
TOST
MCLR Pulse Width (low)
Watchdog Timer Time-out Period
(no postscaler)
Oscillation Start-up Timer Period
33
TPWRT
Power-up Timer Period
34
TIOZ
I/O High-Impedance from MCLR
Low or Watchdog Timer Reset
35
36
TBOR
TIRVST
Brown-out Reset Pulse Width
Time for Internal Reference
Voltage to become Stable
200
—
—
20
—
50
μs
μs
VDD ≤ BVDD (see D005)
37
38
TLVD
TCSD
High/Low-Voltage Detect Pulse Width
CPU Start-up Time
200
—
—
10
—
—
μs
μs
VDD ≤ VLVD
39
TIOBST
Time for INTOSC to Stabilize
—
1
—
μs
© 2008 Microchip Technology Inc.
TOSC = OSC1 period
DS39631E-page 345
PIC18F2420/2520/4420/4520
FIGURE 26-10:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI
41
40
42
T1OSO/T13CKI
46
45
47
48
TMR0 or
TMR1
Note:
Refer to Figure 26-5 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
45
Tt1H
47
—
ns
10
—
ns
0.5 TCY + 20
—
ns
ns
—
ns
With prescaler
Greater of:
20 ns or
(TCY + 40)/N
—
ns
T13CKI
Synchronous, no prescaler
High Time Synchronous,
PIC18FXXXX
with prescaler
PIC18LFXXXX
0.5 TCY + 20
—
ns
10
—
ns
25
—
ns
30
—
ns
PIC18FXXXX
T13CKI
Low Time
Synchronous, no prescaler
50
—
ns
0.5 TCY + 5
—
ns
N = prescale
value
(1, 2, 4,..., 256)
VDD = 2.0V
VDD = 2.0V
Synchronous,
with prescaler
PIC18FXXXX
10
—
ns
PIC18LFXXXX
25
—
ns
Asynchronous
PIC18FXXXX
30
—
ns
PIC18LFXXXX
50
—
ns
VDD = 2.0V
Greater of:
20 ns or
(TCY + 40)/N
—
ns
N = prescale
value (1, 2, 4, 8)
Tt1P
T13CKI
Input
Period
Ft1
T13CKI Oscillator Input Frequency Range
Synchronous
Tcke2tmrI Delay from External T13CKI Clock Edge to
Timer Increment
DS39631E-page 346
0.5 TCY + 20
—
Asynchronous
48
Units Conditions
10
No prescaler
PIC18LFXXXX
Tt1L
Max
TCY + 10
Asynchronous
46
Min
60
—
ns
DC
50
kHz
2 TOSC
7 TOSC
—
VDD = 2.0V
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-11:
CAPTURE/COMPARE/PWM TIMINGS (ALL CCP MODULES)
CCPx
(Capture Mode)
50
51
52
CCPx
(Compare or PWM Mode)
53
Note:
54
Refer to Figure 26-5 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
PIC18FXXXX
prescaler PIC18LFXXXX
0.5 TCY + 20
—
ns
10
—
ns
20
—
ns
CCPx Input
High Time
0.5 TCY + 20
—
ns
No prescaler
With
prescaler
52
TccP
CCPx Input Period
53
TccR
CCPx Output Fall Time
54
TccF
CCPx Output Fall Time
© 2008 Microchip Technology Inc.
Conditions
VDD = 2.0V
PIC18FXXXX
10
—
ns
PIC18LFXXXX
20
—
ns
VDD = 2.0V
3 TCY + 40
N
—
ns
N = prescale
value (1, 4 or 16)
PIC18FXXXX
—
25
ns
PIC18LFXXXX
—
45
ns
PIC18FXXXX
—
25
ns
PIC18LFXXXX
—
45
ns
VDD = 2.0V
VDD = 2.0V
DS39631E-page 347
PIC18F2420/2520/4420/4520
FIGURE 26-12:
PARALLEL SLAVE PORT TIMING (PIC18F4420/4520)
RE2/CS
RE0/RD
RE1/WR
65
RD<7:0>
62
64
63
Note:
Refer to Figure 26-5 for load conditions.
TABLE 26-13: PARALLEL SLAVE PORT REQUIREMENTS (PIC18F4420, PIC18F4520)
Param.
No.
Symbol
Characteristic
62
TdtV2wrH
Data In Valid before WR ↑ or CS ↑ (setup
time)
63
TwrH2dtI
WR ↑ or CS ↑ to Data–In
Invalid (hold time)
Min
Max
Units
20
—
ns
PIC18FXXXX
20
—
ns
PIC18LFXXXX
35
—
ns
80
ns
ns
TrdL2dtV
RD ↓ and CS ↓ to Data–Out Valid
—
65
TrdH2dtI
RD ↑ or CS ↓ to Data–Out Invalid
10
30
66
TibfINH
Inhibit of the IBF Flag bit being Cleared from
WR ↑ or CS ↑
—
3 TCY
64
DS39631E-page 348
Conditions
VDD = 2.0V
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-13:
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 26-5 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
TCY
—
ns
73
TdiV2scH,
TdiV2scL
Setup Time of SDI Data Input to SCK Edge
20
—
ns
73A
Tb2b
Last Clock Edge of Byte 1 to the 1st Clock Edge
of Byte 2
1.5 TCY + 40
—
ns
74
TscH2diL,
TscL2diL
Hold Time of SDI Data Input to SCK Edge
40
—
ns
75
TdoR
SDO Data Output Rise Time
—
25
ns
76
TdoF
SDO Data Output Fall Time
78
TscR
SCK Output Rise Time
(Master mode)
PIC18FXXXX
PIC18LFXXXX
—
45
ns
—
25
ns
PIC18FXXXX
—
25
ns
PIC18LFXXXX
—
45
ns
79
TscF
SCK Output Fall Time (Master mode)
—
25
ns
80
TscH2doV,
TscL2doV
SDO Data Output Valid after
SCK Edge
PIC18FXXXX
—
50
ns
PIC18LFXXXX
—
100
ns
Note 1:
2:
Conditions
(Note 2)
VDD = 2.0V
VDD = 2.0V
VDD = 2.0V
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
© 2008 Microchip Technology Inc.
DS39631E-page 349
PIC18F2420/2520/4420/4520
FIGURE 26-14:
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 26-5 for load conditions.
TABLE 26-15: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 1)
Param.
No.
Symbol
Characteristic
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
75
TdoR
Min
Max Units
20
—
ns
1.5 TCY + 40
—
ns
Hold Time of SDI Data Input to SCK Edge
40
—
ns
SDO Data Output Rise Time
PIC18FXXXX
—
25
ns
PIC18LFXXXX
—
45
ns
—
25
ns
PIC18FXXXX
—
25
ns
PIC18LFXXXX
76
TdoF
SDO Data Output Fall Time
78
TscR
SCK Output Rise Time
(Master mode)
—
45
ns
79
TscF
SCK Output Fall Time (Master mode)
—
25
ns
80
TscH2doV,
TscL2doV
SDO Data Output Valid after
SCK Edge
PIC18FXXXX
—
50
ns
PIC18LFXXXX
—
100
ns
TdoV2scH,
TdoV2scL
SDO Data Output Setup to SCK Edge
TCY
—
ns
81
Note 1:
2:
Conditions
(Note 2)
VDD = 2.0V
VDD = 2.0V
VDD = 2.0V
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
DS39631E-page 350
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-15:
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
bit 6 - - - -1
LSb In
74
73
Refer to Figure 26-5 for load conditions.
Note:
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
3 TCY
Max Units Conditions
—
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
20
—
ns
73
TdiV2scH, Setup Time of SDI Data Input to SCK Edge
TdiV2scL
73A
Tb2b
—
ns
74
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
40
—
ns
75
TdoR
PIC18FXXXX
—
25
ns
PIC18LFXXXX
—
45
ns
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40
SDO Data Output Rise Time
76
TdoF
—
25
ns
77
TssH2doZ SS ↑ to SDO Output High-Impedance
10
50
ns
80
TscH2doV, SDO Data Output Valid after SCK Edge PIC18FXXXX
TscL2doV
PIC18LFXXXX
—
50
ns
—
100
ns
1.5 TCY + 40
—
ns
83
Note 1:
2:
SDO Data Output Fall Time
TscH2ssH, SS ↑ after SCK edge
TscL2ssH
(Note 1)
(Note 1)
(Note 2)
VDD = 2.0V
VDD = 2.0V
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
© 2008 Microchip Technology Inc.
DS39631E-page 351
PIC18F2420/2520/4420/4520
FIGURE 26-16:
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 26-5 for load conditions.
TABLE 26-17: EXAMPLE SPI SLAVE MODE REQUIREMENTS (CKE = 1)
Param
No.
Symbol
Characteristic
70
TssL2scH, SS ↓ to SCK ↓ or SCK ↑ Input
TssL2scL
71
TscH
71A
72
TscL
72A
Min
Max Units Conditions
3 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
(Note 1)
—
ns
(Note 2)
—
ns
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40
73A
Tb2b
74
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
75
TdoR
SDO Data Output Rise Time
40
PIC18FXXXX
—
25
ns
PIC18LFXXXX
—
45
ns
76
TdoF
—
25
ns
77
TssH2doZ SS ↑ to SDO Output High-Impedance
10
50
ns
80
TscH2doV, SDO Data Output Valid after SCK
TscL2doV Edge
PIC18FXXXX
—
50
ns
PIC18LFXXXX
—
100
ns
82
TssL2doV SDO Data Output Valid after SS ↓
Edge
PIC18FXXXX
—
50
ns
—
100
ns
83
TscH2ssH, SS ↑ after SCK Edge
TscL2ssH
1.5 TCY + 40
—
ns
Note 1:
2:
SDO Data Output Fall Time
PIC18LFXXXX
(Note 1)
VDD = 2.0V
VDD = 2.0V
VDD = 2.0V
Requires the use of Parameter #73A.
Only if Parameter #71A and #72A are used.
DS39631E-page 352
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
I2C™ BUS START/STOP BITS TIMING
FIGURE 26-17:
SCL
91
93
90
92
SDA
Stop
Condition
Start
Condition
Note:
Refer to Figure 26-5 for load conditions.
TABLE 26-18: I2C™ BUS START/STOP BITS REQUIREMENTS (SLAVE MODE)
Param.
Symbol
No.
90
91
92
93
TSU:STA
THD:STA
TSU:STO
Characteristic
Max
Units
Conditions
ns
Only relevant for Repeated
Start condition
ns
After this period, the first
clock pulse is generated
Start Condition
100 kHz mode
4700
—
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
400 kHz mode
600
—
100 kHz mode
4000
—
400 kHz mode
600
—
THD:STO Stop Condition
Hold Time
FIGURE 26-18:
Min
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 26-5 for load conditions.
© 2008 Microchip Technology Inc.
DS39631E-page 353
PIC18F2420/2520/4420/4520
TABLE 26-19: I2C™ BUS DATA REQUIREMENTS (SLAVE MODE)
Param.
Symbol
No.
100
THIGH
101
91
106
107
92
109
110
2:
—
μs
μs
—
—
100 kHz mode
4.7
—
μs
400 kHz mode
1.3
—
μs
MSSP module
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
—
μs
400 kHz mode
0.6
—
μs
Only relevant for Repeated
Start condition
THD:STA Start Condition
Hold Time
100 kHz mode
4.0
—
μs
400 kHz mode
0.6
—
μs
THD:DAT Data Input Hold
Time
100 kHz mode
0
—
ns
400 kHz mode
0
0.9
μs
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
—
μs
400 kHz mode
0.6
—
μs
TAA
100 kHz mode
—
3500
ns
400 kHz mode
—
—
ns
CB
Note 1:
4.0
Conditions
0.6
TBUF
D102
Units
1.5 TCY
TF
90
100 kHz mode
Max
MSSP module
TR
103
Clock High Time
Min
400 kHz mode
TLOW
102
Characteristic
Clock Low Time
SDA and SCL Rise 100 kHz mode
Time
400 kHz mode
SDA and SCL Fall
Time
Output Valid from
Clock
Bus Free Time
100 kHz mode
4.7
—
μs
400 kHz mode
1.3
—
μs
—
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.
DS39631E-page 354
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
MASTER SSP I2C™ BUS START/STOP BITS TIMING WAVEFORMS
FIGURE 26-19:
SCL
93
91
90
92
SDA
Stop
Condition
Start
Condition
Note:
Refer to Figure 26-5 for load conditions.
TABLE 26-20: MASTER SSP I2C™ BUS START/STOP BITS REQUIREMENTS
Param.
Symbol
No.
90
91
TSU:STA
Characteristic
ns
Only relevant for
Repeated Start
condition
ns
After this period, the
first clock pulse is
generated
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)
—
100 kHz mode
2(TOSC)(BRG + 1)
—
400 kHz mode
2(TOSC)(BRG + 1)
—
1 MHz mode(1)
2(TOSC)(BRG + 1)
—
THD:STA Start Condition
TSU:STO Stop Condition
THD:STO Stop Condition
Hold Time
Note 1: Maximum pin capacitance = 10 pF for all
FIGURE 26-20:
Units
Setup Time
Setup Time
93
Max
Start Condition
Hold Time
92
Min
I2C
Conditions
ns
ns
pins.
MASTER SSP I2C™ BUS DATA TIMING
103
102
100
101
SCL
90
106
91
107
92
SDA
In
109
109
110
SDA
Out
Note:
Refer to Figure 26-5 for load conditions.
© 2008 Microchip Technology Inc.
DS39631E-page 355
PIC18F2420/2520/4420/4520
TABLE 26-21: MASTER SSP I2C™ BUS DATA REQUIREMENTS
Param.
Symbol
No.
100
101
THIGH
TLOW
Characteristic
Min
Max
Units
Clock High 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
Clock Low Time 100 kHz mode
2(TOSC)(BRG + 1)
—
ms
400 kHz mode
2(TOSC)(BRG + 1)
—
ms
(1)
2(TOSC)(BRG + 1)
—
ms
100 kHz mode
—
1000
ns
400 kHz mode
20 + 0.1 CB
300
ns
1 MHz mode(1)
—
300
ns
1 MHz mode
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
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
92
TSU:STO Stop Condition
Setup Time
109
110
D102
Note 1:
2:
TAA
TBUF
CB
Data Input
Setup Time
Output Valid
from Clock
Bus Free Time
400 kHz mode
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
—
3500
ns
400 kHz mode
—
1000
ns
(1)
1 MHz mode
—
—
ns
100 kHz mode
4.7
—
ms
400 kHz mode
1.3
—
ms
—
400
pF
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
2C
Maximum pin capacitance = 10 pF for all I 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.
DS39631E-page 356
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-21:
EUSART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
RC6/TX/CK
pin
121
121
RC7/RX/DT
pin
120
Note:
122
Refer to Figure 26-5 for load conditions.
TABLE 26-22: EUSART SYNCHRONOUS TRANSMISSION REQUIREMENTS
Param
No.
120
121
122
Symbol
Characteristic
TckH2dtV SYNC XMIT (MASTER & SLAVE)
Clock High to Data Out Valid
Tckrf
Tdtrf
Min
Max
Units
PIC18FXXXX
—
40
ns
PIC18LFXXXX
—
100
ns
Clock Out Rise Time and Fall Time
(Master mode)
PIC18FXXXX
—
20
ns
PIC18LFXXXX
—
50
ns
Data Out Rise Time and Fall Time
PIC18FXXXX
—
20
ns
PIC18LFXXXX
—
50
ns
© 2008 Microchip Technology Inc.
Conditions
VDD = 2.0V
VDD = 2.0V
VDD = 2.0V
DS39631E-page 357
PIC18F2420/2520/4420/4520
FIGURE 26-22:
EUSART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
RC6/TX/CK
pin
125
RC7/RX/DT
pin
126
Note:
Refer to Figure 26-5 for load conditions.
TABLE 26-23: EUSART SYNCHRONOUS RECEIVE REQUIREMENTS
Param.
No.
Symbol
Characteristic
Min
Max
Units
125
TdtV2ckl
SYNC RCV (MASTER & SLAVE)
Data Hold before CK ↓ (DT hold time)
10
—
ns
126
TckL2dtl
Data Hold after CK ↓ (DT hold time)
15
—
ns
Conditions
TABLE 26-24: A/D CONVERTER CHARACTERISTICS: PIC18F2420/2520/4420/4520 (INDUSTRIAL)
PIC18LF2420/2520/4420/4520 (INDUSTRIAL)
Param
Symbol
No.
Characteristic
Min
Typ
Max
Units
Conditions
ΔVREF ≥ 3.0V
A01
NR
Resolution
—
—
10
A03
EIL
Integral Linearity Error
—
—
<±1
LSb ΔVREF ≥ 3.0V
A04
EDL
Differential Linearity Error
—
—
<±1
LSb ΔVREF ≥ 3.0V
A06
EOFF
Offset Error
—
—
<±2.0
LSb ΔVREF ≥ 3.0V
A07
EGN
Gain Error
—
—
<±1
LSb ΔVREF ≥ 3.0V
A10
—
Monotonicity
A20
ΔVREF
Reference Voltage Range
(VREFH – VREFL)
1.8
3
—
—
A21
VREFH
Reference Voltage High
VSS
A22
VREFL
Reference Voltage Low
A25
VAIN
Analog Input Voltage
A30
ZAIN
Recommended Impedance of
Analog Voltage Source
A40
IAD
A/D Current from PIC18FXXXX
VDD
PIC18LFXX20
A50
IREF
Note 1:
2:
VREF Input Current(2)
Guaranteed(1)
bit
—
VSS ≤ VAIN ≤ VREF
—
—
V
V
VDD < 3.0V
VDD ≥ 3.0V
—
VREFH
V
VSS – 0.3V
—
VDD – 3.0V
V
VREFL
—
VREFH
V
—
—
2.5
kΩ
—
180
—
μA
—
90
—
μA
—
—
—
—
5
150
μA
μA
Average current during
conversion
During VAIN acquisition.
During A/D conversion
cycle.
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.
DS39631E-page 358
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-23:
A/D CONVERSION TIMING
BSF ADCON0, GO
(Note 2)
131
Q4
130
132
(1)
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)
μs
TOSC based, VREF ≥ 3.0V
PIC18LFXXXX
1.4
25.0(1)
μs
VDD = 2.0V;
TOSC based, VREF full range
PIC18FXXXX
—
1
μs
A/D RC mode
VDD = 2.0V; A/D RC mode
PIC18FXXXX
PIC18LFXXXX
—
3
μs
131
TCNV
Conversion Time
(not including acquisition time) (Note 2)
11
12
TAD
132
TACQ
Acquisition Time (Note 3)
1.4
—
μs
135
TSWC
Switching Time from Convert → Sample
—
(Note 4)
TBD
TDIS
Discharge Time
0.2
—
Note 1:
2:
3:
4:
Conditions
-40°C to +85°C
μs
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 50Ω.
On the following cycle of the device clock.
© 2008 Microchip Technology Inc.
DS39631E-page 359
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 360
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
27.0
DC AND AC CHARACTERISTICS GRAPHS AND TABLES
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore, outside the warranted range.
Note:
“Typical” represents the mean of the distribution at 25°C. “Maximum” or “minimum” represents (mean + 3σ) or (mean – 3σ)
respectively, where σ is a standard deviation, over the whole temperature range.
FIGURE 27-1:
SLEEP MODE
100
Test instrument results are compressed to about 0.05 μA for actual values below 0.05 mA.
Measurements below 0.01 mA are suspect and considered unmeasurable .
This is supported by the instrument specifications.
10
5.5
5.0
Ipd (uA)
4.5
4.0
3.5
1
3.0
2.5
2.0
0.1
0.01
-50
-25
0
25
50
75
100
125
Temp (C)
© 2008 Microchip Technology Inc.
DS39631E-page 361
PIC18F2420/2520/4420/4520
FIGURE 27-2:
TYPICAL IPD vs. VDD ACROSS TEMPERATURE (SLEEP MODE)
100
10
IPD (uA)
125°C
85°C
1
25°C
0.1
-40°C
0.01
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
5.0
5.5
VDD (V)
FIGURE 27-3:
MAXIMUM IPD vs. VDD ACROSS TEMPERATURE (SLEEP MODE)
100
125°C
10
IPD (uA)
85°C
1
25°C
-40°C
0.1
0.01
2.0
2.5
3.0
3.5
4.0
4.5
VDD (V)
DS39631E-page 362
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-4:
TYPICAL T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP,
T1OSC IN LOW-POWER MODE)
3.0
2.5
IPD (uA)
2.0
85°C
1.5
25°C
1.0
-10°C
0.5
0.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
FIGURE 27-5:
MAXIMUM T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP,
TIOSC IN LOW-POWER MODE)
4
3
IPD (uA)
85°C
25°C
-10°C
2
1
0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
© 2008 Microchip Technology Inc.
DS39631E-page 363
PIC18F2420/2520/4420/4520
FIGURE 27-6:
TYPICAL T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP,
T1OSC IN HIGH-POWER MODE)
16
14
12
IPD (uA)
10
8
85°C
25°C
6
-40°C
4
2
0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
DD
FIGURE 27-7:
MAXIMUM T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP,
T1OSC IN HIGH-POWER MODE)
30
25
IPD (uA)
20
15
85°C
10
25°C
-40°C
5
0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V DD (V)
DS39631E-page 364
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-8:
TYPICAL BOR DELTA CURRENT vs. VDD ACROSS TEMP.
(BORV = 2.7V, SLEEP MODE)
55.00
50.00
Device
Held in
RESET
45.00
MAX
IPD (uA)
MAX (85°C)
40.00
TYP (25°C)
35.00
MIN (-40°C)
30.00
Device
in
SLEEP
25.00
20.00
2
2.5
3
3.5
4
4.5
5
5.5
VDD (V)
© 2008 Microchip Technology Inc.
DS39631E-page 365
PIC18F2420/2520/4420/4520
FIGURE 27-9:
TYPICAL WDT CURRENT vs. VDD ACROSS TEMPERATURE
(WDT DELTA CURRENT IN SLEEP MODE)
6.00
125°C
5.00
25°C
-40°C
4.00
IPD (uA)
85°C
3.00
2.00
1.00
0.00
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
FIGURE 27-10:
MAXIMUM WDT CURRENT vs. VDD ACROSS TEMPERATURE
(WDT DELTA CURRENT IN SLEEP MODE)
12.0
10.0
125°C
8.0
IPD (uA)
85°C
6.0
25°C
-40°C
4.0
2.0
0.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
DS39631E-page 366
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-11:
TYPICAL IDD ACROSS VDD (RC_RUN MODE, +25°C)
10
4.2V
8 MHz
IDD (mA)
4 MHz
2 MHz
1 MHz
1
500 kHz
250 kHz
125 kHz
0.1
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
FIGURE 27-12:
MAXIMUM IDD ACROSS VDD (RC_RUN MODE, +85°C)
10
8 MHz
4.2V
IDD (mA)
4 MHz
2 MHz
1 MHz
1
500 kHz
250 kHz
125 kHz
0.1
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
© 2008 Microchip Technology Inc.
DS39631E-page 367
PIC18F2420/2520/4420/4520
FIGURE 27-13:
TYPICAL AND MAXIMUM IDD ACROSS VDD (RC_RUN MODE, 31 kHz)
IDD (uA)
1000
Maximum
(-40°C)
100
Typical
(25°C)
10
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
FIGURE 27-14:
TYPICAL IDD ACROSS VDD (RC_IDLE MODE, +25°C)
10
4.2V
1
8 MHz
4 MHz
IDD (mA)
2 MHz
1 MHz
250 kHz
125 kHz
0.1
500 kHz
0.01
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
DS39631E-page 368
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-15:
MAXIMUM IDD ACROSS VDD (RC_IDLE MODE, -40°C TO +85°C)
10
4.2V
IDD (mA)
8 MHz
4 MHz
1
2 MHz
1 MHz
500 kHz
250 kHz
125 kHz
0.1
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
FIGURE 27-16:
TYPICAL AND MAXIMUM IDD ACROSS VDD (RC_IDLE MODE, 31 kHz)
25
20
IDD (uA)
15
Maximum
(85°C)
10
Typical
(25°C)
5
0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
© 2008 Microchip Technology Inc.
DS39631E-page 369
PIC18F2420/2520/4420/4520
FIGURE 27-17:
TYPICAL AND MAXIMUM SEC_RUN CURRENT vs. VDD ACROSS TEMPERATURE
(T1OSC IN LOW-POWER MODE)
140.0
120.0
Max (-10°C)
IDD (uA)
100.0
80.0
60.0
Typ (25°C)
Typ (85°C)
Typ (-10°C)
40.0
20.0
0.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
FIGURE 27-18:
TYPICAL AND MAXIMUM SEC_IDLE CURRENT vs. VDD ACROSS TEMPERATURE
(T1OSC IN LOW-POWER MODE)
14.0
12.0
Typ (25°C)
10.0
IDD (uA)
Max (85°C)
8.0
Typ (85°C)
6.0
Typ (-10°C)
4.0
2.0
0.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
DS39631E-page 370
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-19:
TYPICAL IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_RUN MODE (EC CLOCK), +25°C)
3.0
2.5
5.5V
5.0V
IDD (mA)
2.0
4.5V
4.0V
1.5
3.5V
3.0V
1.0
2.5V
2.0V
0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Fosc (MHz)
FIGURE 27-20:
MAXIMUM IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_RUN MODE (EC CLOCK),
-40°C TO +125°C)
4.5
5.5V
IDD (mA)
4.0
3.5
5.0V
3.0
4.5V
2.5
4.0V
2.0
3.5V
1.5
3.0V
1.0
2.5V
2.0V
0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Fosc (MHz)
© 2008 Microchip Technology Inc.
DS39631E-page 371
PIC18F2420/2520/4420/4520
FIGURE 27-21:
TYPICAL IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_RUN MODE (EC CLOCK), +25°C)
20
5.5V
18
5.0V
16
4.5V
14
4.0V
IDD (mA)
12
10
3.5V
8
6
3.0V
4
2.5V
2
2.0V
0
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
Fosc (MHz)
FIGURE 27-22:
MAXIMUM IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_RUN MODE (EC CLOCK),
-40°C TO +125°C)
24
22
5.5V
20
5.0V
18
4.5V
IDD (mA)
16
4.0V
14
12
10
3.5V
8
6
3.0V
4
2.5V
2
2.0V
0
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
Fosc (MHz)
DS39631E-page 372
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-23:
TYPICAL IDD vs. FOSC, HS/PLL (PRI_RUN MODE, +25°C)
24
22
20
18
5.5V
IDD (mA)
16
5.0V
14
4.5V
12
4.2V
10
8
6
4
16
18
20
22
24
26
28
30
32
34
36
38
40
34
36
38
40
Fosc (MHz)
FIGURE 27-24:
MAXIMUM IDD vs. FOSC, HS/PLL (PRI_RUN MODE, -40°C)
24
22
20
5.5V
18
5.0V
I DD (mA)
16
4.5V
14
4.2V
12
10
8
6
4
16
18
20
22
24
26
28
30
32
Fosc (MHz)
© 2008 Microchip Technology Inc.
DS39631E-page 373
PIC18F2420/2520/4420/4520
FIGURE 27-25:
TYPICAL IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_IDLE MODE, +25°C)
1.1
1.0
0.9
5.5V
0.8
5.0V
IDD (mA)
0.7
4.5V
0.6
4.0V
0.5
3.5V
0.4
3.0V
2.5V
0.3
2.0V
0.2
0.1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Fosc (MHz)
FIGURE 27-26:
MAXIMUM IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_IDLE MODE, -40°C TO +125°C)
1.2
1.1
1.0
5.5V
0.9
5.0V
IDD (mA)
0.8
4.5V
0.7
4.0V
0.6
3.5V
0.5
3.0V
0.4
2.5V
0.3
2.0V
0.2
0.1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Fosc (MHz)
DS39631E-page 374
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-27:
TYPICAL IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_IDLE MODE, +25°C)
12
11
IDD (mA)
10
9
5.5V
8
5.0V
7
4.5V
4.0V
6
5
3.5V
4
3
3.0V
2
2.5V
1
2.0V
0
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
Fosc (MHz)
FIGURE 27-28:
MAXIMUM IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_IDLE MODE, -40°C TO +125°C)
12
11
10
5.5V
9
5.0V
8
IDD (mA)
4.5V
7
4.0V
6
5
3.5V
4
3
3.0V
2
2.5V
1
2.0V
0
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
Fosc (MHz)
© 2008 Microchip Technology Inc.
DS39631E-page 375
PIC18F2420/2520/4420/4520
FIGURE 27-29:
TYPICAL IDD vs. FOSC, HS/PLL (PRI_IDLE MODE, +25°C)
12
11
10
9
IDD (mA)
8
5.5V
7
5.0V
6
4.5V
4.2V
5
4
3
2
1
0
16
18
20
22
24
26
28
30
32
34
36
38
40
34
36
38
40
Fosc (MHz)
FIGURE 27-30:
MAXIMUM IDD vs. FOSC, HS/PLL (PRI_IDLE MODE, -40°C)
12
11
10
9
5.5V
8
IDD (mA)
5.0V
7
4.5V
4.2V
6
5
4
3
2
1
0
16
18
20
22
24
26
28
30
32
Fosc (MHz)
DS39631E-page 376
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-31:
VIN (ST) vs. VDD, +25°C (-40°C TO +125°C)
4.0
3.5
3.0
VIH Min
(-40°C)
VIH Typ
(25°C)
VIH Max
(125°C)
VIN (V)
2.5
2.0
1.5
1.0
VIL Min
(125°C)
0.5
VIL Max
(-40°C)
VIL Typ
(25°C)
0.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
4.5
5.0
5.5
VDD (V)
FIGURE 27-32:
VIN (TTL) vs. VDD, +25°C (-40°C TO +125°C)
1.6
VIH Max
(-40°C)
1.4
VIH Typ
(25°C)
VIH Min
(125°C)
1.2
VIN (V)
1.0
0.8
0.6
0.4
0.2
0.0
2.0
2.5
3.0
3.5
4.0
VDD (V)
© 2008 Microchip Technology Inc.
DS39631E-page 377
PIC18F2420/2520/4420/4520
FIGURE 27-33:
VOL vs. IOL (VDD = 3.0V, -40°C TO +85°C)
2.0
1.8
1.6
1.4
Max (85°C)
VOL (V)
1.2
1.0
0.8
Typ (25°C)
0.6
0.4
Min (-40°C)
0.2
0.0
0
5
10
15
20
25
20
25
IOL (-ma)
FIGURE 27-34:
VOL vs. IOL (VDD = 5.0V, -40°C TO +125°C)
2.0
1.8
1.6
1.4
VOL (V)
1.2
1.0
0.8
Max (85°C)
0.6
Typ (25°C)
0.4
0.2
Min (-40°C)
0.0
0
5
10
15
I OL (-ma)
DS39631E-page 378
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-35:
VOH vs. IOH (VDD = 3.0V, -40°C TO +85°C)
3.0
2.5
2.0
VOH (V)
Max (-40°C)
1.5
Typ (25°C)
Min (85°C)
1.0
0.5
0.0
0
5
10
15
20
25
I OH (-ma)
FIGURE 27-36:
VOH vs. IOH (VDD = 5.0V, -40°C TO +125°C)
5.0
4.5
Max (-40°C)
4.0
3.5
Typ (25°C)
VOH (V)
3.0
2.5
Min (125°C)
2.0
1.5
1.0
0.5
0.0
0
5
10
15
20
25
I OH (-ma)
© 2008 Microchip Technology Inc.
DS39631E-page 379
PIC18F2420/2520/4420/4520
FIGURE 27-37:
INTOSC FREQUENCY vs. VDD, TEMPERATURE (-40°C, +25°C, +85°C, +125°C)
8.4
Max Freq
8.3
8.2
125°C Typ
85°C Typ
Freq (MHz)
8.1
25°C Typ
8.0
-40°C Typ
7.9
7.8
Min Freq
7.7
7.6
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
5.0
5.5
VDD (V)
FIGURE 27-38:
INTRC vs. VDD ACROSS TEMPERATURE (-40°C TO +125°C)
40
39
38
37
Max (125°C)
36
Freq (kHz)
35
34
Max (-40°C)
33
32
31
Typ (25°C)
30
Min (85°C)
29
28
27
Min (125°C)
26
25
2.0
2.5
3.0
3.5
4.0
4.5
VDD (V)
DS39631E-page 380
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 27-39:
WDT PERIOD vs. VDD ACROSS TEMPERATURE
(1:1 POSTSCALER, -40°C TO +125°C)
4.6
Longest
4.4
4.2
Shortest (85°C)
Typical (25°C)
Shortest (125°C)
Period (ms)
4.0
3.8
3.6
3.4
3.2
3.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD (V)
© 2008 Microchip Technology Inc.
DS39631E-page 381
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 382
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
28.0
PACKAGING INFORMATION
28.1
Package Marking Information
28-Lead SPDIP
Example
PIC18F2520-I/SP e3
0810017
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXX
YYWWNNN
28-Lead SOIC
Example
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
YYWWNNN
28-Lead QFN
Example
XXXXXXXX
XXXXXXXX
YYWWNNN
18F2420
-I/ML e3
0810017
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
PIC18F2520-E/SO 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.
© 2008 Microchip Technology Inc.
DS39631E-page 383
PIC18F2420/2520/4420/4520
Package Marking Information (Continued)
40-Lead PDIP
Example
PIC18F4420-I/P e3
0810017
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
YYWWNNN
44-Lead QFN
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
44-Lead TQFP
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
DS39631E-page 384
Example
PIC18F4520
-I/ML e3
0810017
Example
PIC18F4420
-I/PT e3
0810017
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
28.2
Package Details
The following sections give the technical details of the packages.
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DS39631E-page 385
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DS39631E-page 387
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PIC18F2420/2520/4420/4520
2.
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DS39631E-page 389
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© 2008 Microchip Technology Inc.
DS39631E-page 393
PIC18F2420/2520/4420/4520
NOTES:
DS39631E-page 394
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
APPENDIX A:
REVISION HISTORY
Revision A (June 2004)
Original data sheet for PIC18F2420/2520/4420/4520
devices.
APPENDIX B:
DEVICE
DIFFERENCES
The differences between the devices listed in this data
sheet are shown in Table B-1.
Revision B (January 2007)
This revision includes updates to the packaging
diagrams.
Revision C (June 2007)
This revision includes updates to Section 6.0 “Flash
Program Memory”, Section 23.0 “Special Features
of the CPU”, Section 26.0 “Electrical Characteristics” and minor corrections applicable to Timer1,
EUSART and the packaging diagrams. Also added the
125°C specifications.
Revision D (July 2007)
This revision updated the extended temperature
information in Section 26.0 “Electrical Characteristics”.
Revision E (October 2008)
This revision updated Section 26.0 “Electrical Characteristics”, Section 27.0 “DC and AC Characteristics
Graphs and Tables” and Section 28.0 “Packaging
Information”.
TABLE B-1:
DEVICE DIFFERENCES
Features
PIC18F2420
PIC18F2520
PIC18F4420
PIC18F4520
Program Memory (Bytes)
16384
32768
16384
32768
Program Memory (Instructions)
8192
16384
8192
16384
Interrupt Sources
19
19
20
20
Ports A, B, C, (E)
Ports A, B, C, (E)
Ports A, B, C, D, E
Ports A, B, C, D, E
Capture/Compare/PWM Modules
2
2
1
1
Enhanced
Capture/Compare/PWM Modules
0
0
1
1
I/O Ports
Parallel Communications (PSP)
No
No
Yes
Yes
10-Bit Analog-to-Digital Module
10 Input Channels
10 Input Channels
13 Input Channels
13 Input Channels
28-Pin SPDIP
28-Pin SOIC
28-Pin QFN
28-Pin SPDIP
28-Pin SOIC
28-Pin QFN
40-Pin PDIP
44-Pin TQFP
44-Pin QFN
40-Pin PDIP
44-Pin TQFP
44-Pin QFN
Packages
© 2008 Microchip Technology Inc.
DS39631E-page 395
PIC18F2420/2520/4420/4520
APPENDIX C:
MIGRATION FROM
MID-RANGE TO
ENHANCED DEVICES
A detailed discussion of the differences between the
mid-range MCU devices (i.e., PIC16CXXX) and the
enhanced devices (i.e., PIC18FXXX) is provided in
AN716, “Migrating Designs from PIC16C74A/74B to
PIC18C442”. The changes discussed, while device
specific, are generally applicable to all mid-range to
enhanced device migrations.
APPENDIX D:
MIGRATION FROM
HIGH-END TO
ENHANCED DEVICES
A detailed discussion of the migration pathway and differences between the high-end MCU devices (i.e.,
PIC17CXXX) and the enhanced devices (i.e.,
PIC18FXXX) is provided in AN726, “PIC17CXXX to
PIC18CXXX Migration”. This Application Note is
available as Literature Number DS00726.
This Application Note is available as Literature Number
DS00716.
DS39631E-page 396
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
INDEX
A
A/D ....................................................................................223
Acquisition Requirements .........................................228
ADCON0 Register.....................................................223
ADCON1 Register.....................................................223
ADCON2 Register.....................................................223
ADRESH Register............................................. 223, 226
ADRESL Register .....................................................223
Analog Port Pins, Configuring ...................................230
Associated Registers ................................................232
Configuring the Module .............................................227
Conversion Clock (TAD) ............................................229
Conversion Status (GO/DONE Bit) ...........................226
Conversions ..............................................................231
Converter Characteristics..........................................359
Converter Interrupt, Configuring................................227
Discharge ..................................................................231
Operation in Power-Managed Modes .......................230
Selecting and Configuring Acquisition Time..............229
Special Event Trigger (CCP) .....................................232
Special Event Trigger (ECCP) ..................................148
Use of the CCP2 Trigger ...........................................232
Absolute Maximum Ratings...............................................321
AC (Timing) Characteristics ..............................................340
Load Conditions for Device
Timing Specifications ........................................341
Parameter Symbology...............................................340
Temperature and Voltage Specifications ..................341
Timing Conditions .....................................................341
AC Characteristics
Internal RC Accuracy ................................................343
Access Bank
Mapping with Indexed Literal Offset Mode ..................72
ACKSTAT..........................................................................191
ACKSTAT Status Flag.......................................................191
ADCON0 Register .............................................................223
GO/DONE Bit ............................................................226
ADCON1 Register .............................................................223
ADCON2 Register .............................................................223
ADDFSR............................................................................310
ADDLW .............................................................................273
ADDULNK .........................................................................310
ADDWF .............................................................................273
ADDWFC...........................................................................274
ADRESH Register .............................................................223
ADRESL Register...................................................... 223, 226
Analog-to-Digital Converter. See A/D.
ANDLW .............................................................................274
ANDWF .............................................................................275
Assembler
MPASM Assembler ...................................................318
Auto-Wake-up on Sync Break Character ..........................214
B
Bank Select Register (BSR) ................................................59
Baud Rate Generator ........................................................187
BC .....................................................................................275
BCF ...................................................................................276
BF......................................................................................191
BF Status Flag...................................................................191
DS39631E-page 397
Block Diagrams
A/D............................................................................ 226
Analog Input Model ................................................... 227
Baud Rate Generator................................................ 187
Capture Mode Operation .......................................... 141
Comparator Analog Input Model ............................... 237
Comparator I/O Operating Modes ............................ 234
Comparator Output ................................................... 236
Comparator Voltage Reference ................................ 240
Comparator Voltage Reference Output
Buffer Example ................................................. 241
Compare Mode Operation ........................................ 142
Device Clock............................................................... 28
Enhanced PWM........................................................ 149
EUSART Receive ..................................................... 213
EUSART Transmit .................................................... 211
External Power-on Reset Circuit
(Slow VDD Power-up).......................................... 43
Fail-Safe Clock Monitor (FSCM) ............................... 261
Generic I/O Port........................................................ 105
High/Low-Voltage Detect with External Input ........... 244
Interrupt Logic ............................................................. 92
MSSP (I2C Master Mode) ......................................... 185
MSSP (I2C Mode) ..................................................... 170
MSSP (SPI Mode) .................................................... 161
On-Chip Reset Circuit ................................................. 41
PIC18F2420/2520....................................................... 10
PIC18F4420/4520....................................................... 11
PLL (HS Mode) ........................................................... 25
PORTD and PORTE (Parallel Slave Port) ................ 120
PWM Operation (Simplified) ..................................... 144
Reads from Flash Program Memory........................... 77
Single Comparator .................................................... 235
Table Read Operation ................................................ 73
Table Write Operation................................................. 74
Table Writes to Flash Program Memory ..................... 79
Timer0 in 16-Bit Mode .............................................. 124
Timer0 in 8-Bit Mode ................................................ 124
Timer1....................................................................... 128
Timer1 (16-Bit Read/Write Mode) ............................. 128
Timer2....................................................................... 134
Timer3....................................................................... 136
Timer3 (16-Bit Read/Write Mode) ............................. 136
Watchdog Timer ....................................................... 258
BN ..................................................................................... 276
BNC .................................................................................. 277
BNN .................................................................................. 277
BNOV................................................................................ 278
BNZ................................................................................... 278
BOR. See Brown-out Reset.
BOV .................................................................................. 281
BRA................................................................................... 279
Break Character (12-Bit) Transmit and Receive ............... 216
BRG. See Baud Rate Generator.
Brown-out Reset (BOR) ...................................................... 44
Detecting..................................................................... 44
Disabling in Sleep Mode ............................................. 44
Software Enabled ....................................................... 44
BSF ................................................................................... 279
BTFSC .............................................................................. 280
BTFSS .............................................................................. 280
BTG................................................................................... 281
BZ ..................................................................................... 282
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
C
C Compilers
MPLAB C18 .............................................................. 318
MPLAB C30 .............................................................. 318
CALL ................................................................................. 282
CALLW.............................................................................. 311
Capture (CCP Module)...................................................... 141
Associated Registers ................................................ 143
CCP Pin Configuration .............................................. 141
CCPRxH:CCPRxL Registers .................................... 141
Prescaler ................................................................... 141
Software Interrupt ..................................................... 141
Timer1/Timer3 Mode Selection ................................. 141
Capture (ECCP Module) ................................................... 148
Capture/Compare/PWM (CCP)......................................... 139
Capture Mode. See Capture.
CCP Mode and Timer Resources ............................. 140
CCPRxH Register ..................................................... 140
CCPRxL Register...................................................... 140
Compare Mode. See Compare.
Interaction of Two CCP Modules .............................. 140
Module Configuration ................................................ 140
Clock Sources ..................................................................... 28
Selecting the 31 kHz Source....................................... 29
Selection Using OSCCON Register ............................ 29
CLRF................................................................................. 283
CLRWDT........................................................................... 283
Code Examples
16 x 16 Signed Multiply Routine ................................. 90
16 x 16 Unsigned Multiply Routine ............................. 90
8 x 8 Signed Multiply Routine ..................................... 89
8 x 8 Unsigned Multiply Routine ................................. 89
Changing Between Capture Prescalers .................... 141
Computed GOTO Using an Offset Value .................... 56
Data EEPROM Read .................................................. 85
Data EEPROM Refresh Routine ................................. 86
Data EEPROM Write .................................................. 85
Erasing a Flash Program Memory Row ...................... 78
Fast Register Stack..................................................... 56
How to Clear RAM (Bank 1) Using
Indirect Addressing ............................................. 68
Implementing a Real-Time Clock Using
a Timer1 Interrupt Service ................................ 131
Initializing PORTA..................................................... 105
Initializing PORTB..................................................... 108
Initializing PORTC..................................................... 111
Initializing PORTD..................................................... 114
Initializing PORTE..................................................... 117
Loading the SSPBUF (SSPSR) Register .................. 164
Reading a Flash Program Memory Word ................... 77
Saving STATUS, WREG and BSR
Registers in RAM .............................................. 103
Writing to Flash Program Memory ........................ 80–81
Code Protection ................................................................ 249
COMF................................................................................ 284
Comparator ....................................................................... 233
Analog Input Connection Considerations.................. 237
Associated Registers ................................................ 237
Configuration............................................................. 234
Effects of a Reset...................................................... 236
Interrupts................................................................... 236
Operation .................................................................. 235
Operation During Sleep ............................................ 236
Outputs ..................................................................... 235
Reference ................................................................. 235
DS39631E-page 398
External Signal ................................................. 235
Internal Signal................................................... 235
Response Time......................................................... 235
Comparator Specifications................................................ 338
Comparator Voltage Reference ........................................ 239
Accuracy and Error ................................................... 240
Associated Registers ................................................ 241
Configuring ............................................................... 239
Connection Considerations....................................... 240
Effects of a Reset ..................................................... 240
Operation During Sleep ............................................ 240
Compare (CCP Module) ................................................... 142
Associated Registers ................................................ 143
CCPRx Register ....................................................... 142
Pin Configuration ...................................................... 142
Software Interrupt ..................................................... 142
Special Event Trigger ............................... 137, 142, 232
Timer1/Timer3 Mode Selection................................. 142
Compare (ECCP Module)................................................. 148
Special Event Trigger ............................................... 148
Computed GOTO................................................................ 56
Configuration Bits ............................................................. 249
Configuration Register Protection..................................... 266
Context Saving During Interrupts...................................... 103
CPFSEQ ........................................................................... 284
CPFSGT ........................................................................... 285
CPFSLT ............................................................................ 285
Crystal Oscillator/Ceramic Resonator................................. 23
Customer Change Notification Service............................. 407
Customer Notification Service .......................................... 407
Customer Support............................................................. 407
D
Data Addressing Modes ..................................................... 68
Comparing Addressing Modes with the
Extended Instruction Set Enabled ...................... 71
Direct .......................................................................... 68
Indexed Literal Offset ................................................. 70
Instructions Affected ........................................... 70
Indirect ........................................................................ 68
Inherent and Literal..................................................... 68
Data EEPROM
Code Protection ........................................................ 266
Data EEPROM Memory...................................................... 83
Associated Registers .................................................. 87
EEADR Register ......................................................... 83
EECON1 and EECON2 Registers .............................. 83
Operation During Code-Protect .................................. 86
Protection Against Spurious Write .............................. 86
Reading ...................................................................... 85
Using .......................................................................... 86
Write Verify ................................................................. 85
Writing ........................................................................ 85
Data Memory ...................................................................... 59
Access Bank............................................................... 62
and the Extended Instruction Set ............................... 70
Bank Select Register (BSR) ....................................... 59
General Purpose Registers ........................................ 62
Map for PIC18F2420/4420 ......................................... 60
Map for PIC18F2520/4520 ......................................... 61
Special Function Registers ......................................... 63
DAW ................................................................................. 286
DC and AC Characteristics
Graphs and Tables ................................................... 361
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
DC Characteristics ............................................................335
Power-Down and Supply Current..............................325
Supply Voltage ..........................................................324
DCFSNZ............................................................................287
DECF.................................................................................286
DECFSZ ............................................................................287
Development Support........................................................317
Device Differences ............................................................395
Device Overview ...................................................................7
Details on Individual Family Members ..........................8
Features (table).............................................................9
New Core Features .......................................................7
Other Special Features .................................................8
Device Reset Timers ...........................................................45
Oscillator Start-up Timer (OST) ..................................45
PLL Lock Time-out ......................................................45
Power-up Timer (PWRT).............................................45
Time-out Sequence .....................................................45
Direct Addressing ................................................................69
E
Effect on Standard PIC MCU Instructions .........................314
Effects of Power-Managed Modes on
Various Clock Sources................................................31
Electrical Characteristics ...................................................321
Enhanced Capture/Compare/PWM (ECCP) .....................147
Associated Registers ................................................160
Capture and Compare Modes...................................148
Capture Mode. See Capture (ECCP Module).
Outputs and Configuration ........................................148
Pin Configurations for ECCP.....................................148
PWM Mode. See PWM (ECCP Module).
Standard PWM Mode................................................148
Timer Resources.......................................................148
Enhanced PWM Mode. See PWM (ECCP Module).
Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART). See EUSART.
Equations
A/D Acquisition Time .................................................228
A/D Minimum Charging Time ....................................228
Calculating the Minimum Required
Acquisition Time................................................228
Errata.....................................................................................6
EUSART
Asynchronous Mode .................................................211
12-Bit Break Transmit and Receive ..................216
Associated Registers, Receive .........................214
Associated Registers, Transmit ........................212
Auto-Wake-up on Sync Break...........................214
Receiver ............................................................213
Setting up 9-Bit Mode with
Address Detect .........................................213
Transmitter ........................................................211
Baud Rate Generator
Operation in Power-Managed Mode .................205
Baud Rate Generator (BRG) .....................................205
Associated Registers ........................................206
Auto-Baud Rate Detect .....................................209
Baud Rate Error, Calculating ............................206
Baud Rates, Asynchronous Modes...................207
High Baud Rate Select (BRGH Bit)...................205
Sampling ...........................................................205
DS39631E-page 399
Synchronous Master Mode ....................................... 217
Associated Registers, Receive ......................... 219
Associated Registers, Transmit ........................ 218
Reception.......................................................... 219
Transmission .................................................... 217
Synchronous Slave Mode ......................................... 220
Associated Registers, Receive ......................... 221
Associated Registers, Transmit ........................ 220
Reception.......................................................... 221
Transmission .................................................... 220
Extended Instruction Set
ADDFSR ................................................................... 310
ADDULNK................................................................. 310
and Using MPLAB IDE Tools.................................... 316
CALLW ..................................................................... 311
Considerations for Use ............................................. 314
MOVSF ..................................................................... 311
MOVSS..................................................................... 312
PUSHL ...................................................................... 312
SUBFSR ................................................................... 313
SUBULNK................................................................. 313
Syntax....................................................................... 309
External Clock Input............................................................ 24
F
Fail-Safe Clock Monitor............................................. 249, 261
Exiting Operation ...................................................... 261
Interrupts in Power-Managed Modes........................ 262
POR or Wake from Sleep ......................................... 262
WDT During Oscillator Failure .................................. 261
Fast Register Stack............................................................. 56
Firmware Instructions........................................................ 267
Flash Program Memory ...................................................... 73
Associated Registers .................................................. 81
Control Registers ........................................................ 74
EECON1 and EECON2 ...................................... 74
TABLAT (Table Latch) Register.......................... 76
TBLPTR (Table Pointer) Register....................... 76
Erase Sequence ......................................................... 78
Erasing........................................................................ 78
Operation During Code-Protect .................................. 81
Reading ...................................................................... 77
Table Pointer
Boundaries Based on Operation......................... 76
Table Pointer Boundaries ........................................... 76
Table Reads and Table Writes ................................... 73
Write Sequence .......................................................... 79
Writing To ................................................................... 79
Protection Against Spurious Writes .................... 81
Unexpected Termination..................................... 81
Write Verify ......................................................... 81
FSCM. See Fail-Safe Clock Monitor.
G
General Call Address Support .......................................... 184
GOTO ............................................................................... 288
H
Hardware Multiplier ............................................................. 89
Introduction ................................................................. 89
Operation .................................................................... 89
Performance Comparison ........................................... 89
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
High/Low-Voltage Detect
Applications............................................................... 246
Associated Registers ................................................ 247
Characteristics .......................................................... 339
Current Consumption ................................................ 245
Effects of a Reset...................................................... 247
Operation .................................................................. 244
During Sleep ..................................................... 247
Setup......................................................................... 245
Start-up Time ............................................................ 245
Typical Application .................................................... 246
HLVD. See High/Low-Voltage Detect.
I
I/O Ports ............................................................................ 105
I2C Mode (MSSP)
Acknowledge Sequence Timing................................ 194
Baud Rate Generator ................................................ 187
Bus Collision
During a Repeated Start Condition ................... 198
During a Stop Condition.................................... 199
Clock Arbitration........................................................ 188
Clock Stretching ........................................................ 180
10-Bit Slave Receive Mode (SEN = 1).............. 180
10-Bit Slave Transmit Mode.............................. 180
7-Bit Slave Receive Mode (SEN = 1)................ 180
7-Bit Slave Transmit Mode................................ 180
Clock Synchronization and the
CKP bit (SEN = 1) ............................................. 181
Effects of a Reset...................................................... 195
General Call Address Support .................................. 184
I2C Clock Rate w/BRG .............................................. 187
Master Mode ............................................................. 185
Operation .......................................................... 186
Reception.......................................................... 191
Repeated Start Condition Timing...................... 190
Start Condition Timing ...................................... 189
Transmission..................................................... 191
Multi-Master Communication, Bus
Collision and Arbitration .................................... 195
Multi-Master Mode .................................................... 195
Operation .................................................................. 174
Read/Write Bit Information (R/W Bit) ................ 174, 175
Registers................................................................... 170
Serial Clock (RC3/SCK/SCL) .................................... 175
Slave Mode ............................................................... 174
Addressing ........................................................ 174
Reception.......................................................... 175
Transmission..................................................... 175
Sleep Operation ........................................................ 195
Stop Condition Timing............................................... 194
ID Locations .............................................................. 249, 266
INCF.................................................................................. 288
INCFSZ ............................................................................. 289
In-Circuit Debugger ........................................................... 266
In-Circuit Serial Programming (ICSP) ....................... 249, 266
Indexed Literal Offset Addressing
and Standard PIC18 Instructions .............................. 314
Indexed Literal Offset Mode .............................................. 314
Indirect Addressing ............................................................. 69
INFSNZ ............................................................................. 289
Initialization Conditions for all Registers ....................... 49–52
Instruction Cycle.................................................................. 57
Clocking Scheme ........................................................ 57
Instruction Flow/Pipelining .................................................. 57
Instruction Set ................................................................... 267
DS39631E-page 400
ADDLW..................................................................... 273
ADDWF..................................................................... 273
ADDWF (Indexed Literal Offset Mode) ..................... 315
ADDWFC .................................................................. 274
ANDLW..................................................................... 274
ANDWF..................................................................... 275
BC............................................................................. 275
BCF .......................................................................... 276
BN............................................................................. 276
BNC .......................................................................... 277
BNN .......................................................................... 277
BNOV ....................................................................... 278
BNZ .......................................................................... 278
BOV .......................................................................... 281
BRA .......................................................................... 279
BSF........................................................................... 279
BSF (Indexed Literal Offset Mode) ........................... 315
BTFSC ...................................................................... 280
BTFSS ...................................................................... 280
BTG .......................................................................... 281
BZ ............................................................................. 282
CALL......................................................................... 282
CLRF ........................................................................ 283
CLRWDT .................................................................. 283
COMF ....................................................................... 284
CPFSEQ ................................................................... 284
CPFSGT ................................................................... 285
CPFSLT .................................................................... 285
DAW ......................................................................... 286
DCFSNZ ................................................................... 287
DECF ........................................................................ 286
DECFSZ ................................................................... 287
Extended Instruction Set .......................................... 309
General Format......................................................... 269
GOTO ....................................................................... 288
INCF ......................................................................... 288
INCFSZ..................................................................... 289
INFSNZ..................................................................... 289
IORLW ...................................................................... 290
IORWF...................................................................... 290
LFSR ........................................................................ 291
MOVF ....................................................................... 291
MOVFF ..................................................................... 292
MOVLB ..................................................................... 292
MOVLW .................................................................... 293
MOVWF .................................................................... 293
MULLW..................................................................... 294
MULWF..................................................................... 294
NEGF........................................................................ 295
NOP .......................................................................... 295
Opcode Field Descriptions........................................ 268
POP .......................................................................... 296
PUSH........................................................................ 296
RCALL ...................................................................... 297
RESET...................................................................... 297
RETFIE ..................................................................... 298
RETLW ..................................................................... 298
RETURN................................................................... 299
RLCF ........................................................................ 299
RLNCF...................................................................... 300
RRCF........................................................................ 300
RRNCF ..................................................................... 301
SETF ........................................................................ 301
SETF (Indexed Literal Offset Mode) ......................... 315
SLEEP ...................................................................... 302
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Standard Instructions ................................................267
SUBFWB...................................................................302
SUBLW .....................................................................303
SUBWF .....................................................................303
SUBWFB...................................................................304
SWAPF .....................................................................304
TBLRD ......................................................................305
TBLWT ......................................................................306
TSTFSZ.....................................................................307
XORLW .....................................................................307
XORWF.....................................................................308
INTCON Registers ........................................................ 93–95
Inter-Integrated Circuit. See I2C.
Internal Oscillator Block.......................................................26
Adjustment ..................................................................26
INTIO Modes...............................................................26
INTOSC Frequency Drift .............................................26
INTOSC Output Frequency.........................................26
OSCTUNE Register ....................................................26
PLL in INTOSC Modes................................................26
Internal RC Oscillator
Use with WDT ...........................................................258
Internet Address ................................................................407
Interrupt Sources...............................................................249
A/D Conversion Complete.........................................227
Capture Complete (CCP) ..........................................141
Compare Complete (CCP) ........................................142
Interrupt-on-Change (RB7:RB4) ...............................108
INTx Pin ....................................................................103
PORTB, Interrupt-on-Change ...................................103
TMR0 ........................................................................103
TMR0 Overflow .........................................................125
TMR1 Overflow .........................................................127
TMR2 to PR2 Match (PWM) ............................. 144, 149
TMR3 Overflow ................................................. 135, 137
Interrupts .............................................................................91
Interrupts, Flag Bits
Interrupt-on-Change (RB7:RB4) Flag
(RBIF Bit) ..........................................................108
INTOSC, INTRC. See Internal Oscillator Block.
IORLW...............................................................................290
IORWF ..............................................................................290
IPR Registers ............................................................100–101
L
LFSR .................................................................................291
Low-Voltage ICSP Programming. See Single-Supply
ICSP Programming
M
Master Clear (MCLR) ..........................................................43
Master Synchronous Serial Port (MSSP). See MSSP.
Memory Organization ..........................................................53
Data Memory...............................................................59
Program Memory ........................................................53
Memory Programming Requirements ...............................337
Microchip Internet Web Site ..............................................407
Migration from High-End to Enhanced Devices ................396
Migration from Mid-Range to Enhanced Devices..............396
MOVF ................................................................................291
MOVFF..............................................................................292
MOVLB..............................................................................292
MOVLW.............................................................................293
MOVSF..............................................................................311
MOVSS .............................................................................312
MOVWF.............................................................................293
DS39631E-page 401
MPLAB ASM30 Assembler, Linker, Librarian ................... 318
MPLAB ICD 2 In-Circuit Debugger ................................... 319
MPLAB ICE 2000 High-Performance
Universal In-Circuit Emulator .................................... 319
MPLAB Integrated Development
Environment Software .............................................. 317
MPLAB PM3 Device Programmer .................................... 319
MPLAB REAL ICE In-Circuit Emulator System................. 319
MPLINK Object Linker/MPLIB Object Librarian ................ 318
MSSP
ACK Pulse ........................................................ 174, 175
Control Registers (general)....................................... 161
I2C Mode. See I2C Mode.
Module Overview ...................................................... 161
SPI Master/Slave Connection ................................... 165
SPI Mode. See SPI Mode.
SSPBUF Register ..................................................... 166
SSPSR Register ....................................................... 166
MULLW ............................................................................. 294
MULWF............................................................................. 294
N
NEGF ................................................................................ 295
NOP .................................................................................. 295
O
Oscillator Configuration....................................................... 23
EC............................................................................... 23
ECIO ........................................................................... 23
HS............................................................................... 23
HSPLL ........................................................................ 23
Internal Oscillator Block .............................................. 26
INTIO1 ........................................................................ 23
INTIO2 ........................................................................ 23
LP ............................................................................... 23
RC............................................................................... 23
RCIO ........................................................................... 23
XT ............................................................................... 23
Oscillator Selection ........................................................... 249
Oscillator Start-up Timer (OST) .................................... 31, 45
Oscillator Switching............................................................. 28
Oscillator Transitions .......................................................... 29
Oscillator, Timer1...................................................... 127, 137
Oscillator, Timer3.............................................................. 135
P
Packaging Information ...................................................... 383
Details....................................................................... 385
Marking ..................................................................... 383
Parallel Slave Port (PSP).......................................... 114, 120
Associated Registers ................................................ 121
CS (Chip Select) ....................................................... 120
PORTD ..................................................................... 120
RD (Read Input)........................................................ 120
Select (PSPMODE Bit) ..................................... 114, 120
WR (Write Input) ....................................................... 120
PICSTART Plus Development Programmer ..................... 320
PIE Registers ................................................................ 98–99
Pin Functions
MCLR/VPP/RE3 .................................................... 12, 16
OSC1/CLKI/RA7 ................................................... 12, 16
OSC2/CLKO/RA6 ................................................. 12, 16
RA0/AN0 ............................................................... 13, 17
RA1/AN1 ............................................................... 13, 17
RA2/AN2/VREF-/CVREF ......................................... 13, 17
RA3/AN3/VREF+.................................................... 13, 17
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
RA4/T0CKI/C1OUT............................................... 13, 17
RA5/AN4/SS/HLVDIN/C2OUT .............................. 13, 17
RB0/INT0/FLT0/AN12 ........................................... 14, 18
RB1/INT1/AN10 .................................................... 14, 18
RB2/INT2/AN8 ...................................................... 14, 18
RB3/AN9/CCP2 .................................................... 14, 18
RB4/KBI0/AN11 .................................................... 14, 18
RB5/KBI1/PGM ..................................................... 14, 18
RB6/KBI2/PGC ..................................................... 14, 18
RB7/KBI3/PGD ..................................................... 14, 18
RC0/T1OSO/T13CKI ............................................ 15, 19
RC1/T1OSI/CCP2 ................................................. 15, 19
RC2/CCP1 .................................................................. 15
RC2/CCP1/P1A .......................................................... 19
RC3/SCK/SCL ...................................................... 15, 19
RC4/SDI/SDA ....................................................... 15, 19
RC5/SDO .............................................................. 15, 19
RC6/TX/CK ........................................................... 15, 19
RC7/RX/DT ........................................................... 15, 19
RD0/PSP0................................................................... 20
RD1/PSP1................................................................... 20
RD2/PSP2................................................................... 20
RD3/PSP3................................................................... 20
RD4/PSP4................................................................... 20
RD5/PSP5/P1B........................................................... 20
RD6/PSP6/P1C........................................................... 20
RD7/PSP7/P1D........................................................... 20
RE0/RD/AN5 ............................................................... 21
RE1/WR/AN6 .............................................................. 21
RE2/CS/AN7 ............................................................... 21
VDD........................................................................ 15, 21
VSS ........................................................................ 15, 21
Pinout I/O Descriptions
PIC18F2420/2520....................................................... 12
PIC18F4420/4520....................................................... 16
PIR Registers ................................................................ 96–97
PLL Frequency Multiplier .................................................... 25
HSPLL Oscillator Mode............................................... 25
Use with INTOSC........................................................ 25
POP................................................................................... 296
POR. See Power-on Reset.
PORTA
Associated Registers ................................................ 107
LATA Register........................................................... 105
PORTA Register ....................................................... 105
TRISA Register ......................................................... 105
PORTB
Associated Registers ................................................ 110
LATB Register........................................................... 108
PORTB Register ....................................................... 108
RB7:RB4 Interrupt-on-Change Flag
(RBIF Bit) .......................................................... 108
TRISB Register ......................................................... 108
PORTC
Associated Registers ................................................ 113
LATC Register .......................................................... 111
PORTC Register ....................................................... 111
RC3/SCK/SCL Pin .................................................... 175
TRISC Register ......................................................... 111
PORTD
Associated Registers ................................................ 116
LATD Register .......................................................... 114
Parallel Slave Port (PSP) Function ........................... 114
PORTD Register ....................................................... 114
TRISD Register ......................................................... 114
DS39631E-page 402
PORTE
Associated Registers ................................................ 119
LATE Register .......................................................... 117
PORTE Register ....................................................... 117
PSP Mode Select (PSPMODE Bit) ........................... 114
TRISE Register......................................................... 117
Power-Managed Modes...................................................... 33
and A/D Operation .................................................... 230
and EUSART Operation ........................................... 205
and Multiple Sleep Commands................................... 34
and PWM Operation ................................................. 159
and SPI Operation .................................................... 169
Clock Transitions and Status Indicators ..................... 34
Effects on Clock Sources............................................ 31
Entering ...................................................................... 33
Exiting Idle and Sleep Modes ..................................... 39
by Interrupt ......................................................... 39
by Reset ............................................................. 39
by WDT Time-out ............................................... 39
Without a Start-up Delay .................................... 40
Idle Modes .................................................................. 37
PRI_IDLE............................................................ 38
RC_IDLE ............................................................ 39
SEC_IDLE .......................................................... 38
Run Modes ................................................................. 34
PRI_RUN............................................................ 34
RC_RUN............................................................. 35
SEC_RUN .......................................................... 34
Selecting ..................................................................... 33
Sleep Mode ................................................................ 37
Summary (table) ......................................................... 33
Power-on Reset (POR)....................................................... 43
Power-up Timer (PWRT) ............................................ 45
Time-out Sequence .................................................... 45
Power-up Delays ................................................................ 31
Power-up Timer (PWRT) .................................................... 31
Prescaler
Timer2 ...................................................................... 150
Prescaler, Timer0 ............................................................. 125
Prescaler, Timer2 ............................................................. 145
PRI_IDLE Mode.................................................................. 38
PRI_RUN Mode .................................................................. 34
Program Counter ................................................................ 54
PCL, PCH and PCU Registers ................................... 54
PCLATH and PCLATU Registers ............................... 54
Program Memory
and Extended Instruction Set ..................................... 72
Code Protection ........................................................ 264
Instructions ................................................................. 58
Two-Word ........................................................... 58
Interrupt Vector ........................................................... 53
Look-up Tables ........................................................... 56
Map and Stack (diagram) ........................................... 53
Reset Vector ............................................................... 53
Program Verification and Code Protection ....................... 263
Associated Registers ................................................ 263
Programming, Device Instructions.................................... 267
PSP. See Parallel Slave Port.
Pulse-Width Modulation. See PWM (CCP Module)
and PWM (ECCP Module).
PUSH................................................................................ 296
PUSH and POP Instructions............................................... 55
PUSHL.............................................................................. 312
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
PWM (CCP Module)
Associated Registers ................................................146
Auto-Shutdown (CCP1 Only) ....................................145
Duty Cycle.................................................................144
Example Frequencies/Resolutions............................145
Period ........................................................................144
Setup for PWM Operation .........................................145
TMR2 to PR2 Match..................................................144
PWM (ECCP Module) .......................................................149
CCPR1H:CCPR1L Registers ....................................149
Direction Change in Full-Bridge
Output Mode .....................................................154
Duty Cycle.................................................................150
Effects of a Reset......................................................159
Enhanced PWM Auto-Shutdown...............................156
Example Frequencies/Resolutions............................150
Full-Bridge Mode.......................................................153
Full-Bridge Output Mode Application Example .........154
Half-Bridge Mode ......................................................152
Half-Bridge Output Mode Applications Example .......152
Operation in Power-Managed Modes .......................159
Operation with Fail-Safe Clock Monitor.....................159
Output Configurations ...............................................150
Output Relationships (Active-High) ...........................151
Output Relationships (Active-Low) ............................151
Period ........................................................................149
Programmable Dead-Band Delay .............................156
Setup for PWM Operation .........................................159
Start-up Considerations ............................................158
TMR2 to PR2 Match..................................................149
Q
Q Clock...................................................................... 145, 150
R
RAM. See Data Memory.
RBIF Bit .............................................................................108
RC Oscillator .......................................................................25
RCIO Oscillator Mode .................................................25
RC_IDLE Mode ...................................................................39
RC_RUN Mode ...................................................................35
RCALL...............................................................................297
RCON Register
Bit Status During Initialization .....................................48
Reader Response .............................................................408
Register File ........................................................................62
Register File Summary.................................................. 64–66
Registers
ADCON0 (A/D Control 0) ..........................................223
ADCON1 (A/D Control 1) ..........................................224
ADCON2 (A/D Control 2) ..........................................225
BAUDCON (Baud Rate Control) ...............................204
CCP1CON (ECCP Control,
40/44-Pin Devices)............................................147
CCPxCON (CCPx Control, 28-Pin Devices) .............139
CMCON (Comparator Control)..................................233
CONFIG1H (Configuration 1 High) ...........................250
CONFIG2H (Configuration 2 High) ...........................252
CONFIG2L (Configuration 2 Low) .............................251
CONFIG3H (Configuration 3 High) ...........................253
CONFIG4L (Configuration 4 Low) .............................253
CONFIG5H (Configuration 5 High) ...........................254
CONFIG5L (Configuration 5 Low) .............................254
CONFIG6H (Configuration 6 High) ...........................255
CONFIG6L (Configuration 6 Low) .............................255
CONFIG7H (Configuration 7 High) ...........................256
DS39631E-page 403
CONFIG7L (Configuration 7 Low) ............................ 256
CVRCON (Comparator Voltage
Reference Control) ........................................... 239
DEVID1 (Device ID 1) ............................................... 257
DEVID2 (Device ID 2) ............................................... 257
ECCP1AS (ECCP Auto-Shutdown Control) ............. 157
EECON1 (EEPROM Control 1) ............................ 75, 84
HLVDCON (High/Low-Voltage Detect Control) ........ 243
INTCON (Interrupt Control)......................................... 93
INTCON2 (Interrupt Control 2).................................... 94
INTCON3 (Interrupt Control 3).................................... 95
IPR1 (Peripheral Interrupt Priority 1) ........................ 100
IPR2 (Peripheral Interrupt Priority 2) ........................ 101
OSCCON (Oscillator Control) ..................................... 30
OSCTUNE (Oscillator Tuning) .................................... 27
PIE1 (Peripheral Interrupt Enable 1)........................... 98
PIE2 (Peripheral Interrupt Enable 2)........................... 99
PIR1 (Peripheral Interrupt Request (Flag) 1) .............. 96
PIR2 (Peripheral Interrupt Request (Flag) 2) .............. 97
PWM1CON (PWM Dead-Band Delay) ..................... 156
RCON (Reset Control) ........................................ 42, 102
RCSTA (Receive Status and Control) ...................... 203
SSPCON1 (MSSP Control 1, I2C Mode) .................. 172
SSPCON1 (MSSP Control 1, SPI Mode).................. 163
SSPCON2 (MSSP Control 2, I2C Mode) .................. 173
SSPSTAT (MSSP Status, I2C Mode) ....................... 171
SSPSTAT (MSSP Status, SPI Mode) ....................... 162
STATUS...................................................................... 67
STKPTR (Stack Pointer) ............................................. 55
T0CON (Timer0 Control) .......................................... 123
T1CON (Timer1 Control) .......................................... 127
T2CON (Timer2 Control) .......................................... 133
T3CON (Timer3 Control) .......................................... 135
TRISE (PORTE/PSP Control)................................... 118
TXSTA (Transmit Status and Control) ...................... 202
WDTCON (Watchdog Timer Control) ....................... 259
RESET .............................................................................. 297
Reset State of Registers ..................................................... 48
Resets......................................................................... 41, 249
Brown-out Reset (BOR) ............................................ 249
Oscillator Start-up Timer (OST) ................................ 249
Power-on Reset (POR) ............................................. 249
Power-up Timer (PWRT) .......................................... 249
RETFIE ............................................................................. 298
RETLW ............................................................................. 298
RETURN ........................................................................... 299
Return Address Stack ......................................................... 54
Return Stack Pointer (STKPTR) ......................................... 55
Revision History ................................................................ 395
RLCF................................................................................. 299
RLNCF .............................................................................. 300
RRCF ................................................................................ 300
RRNCF ............................................................................. 301
S
SCK................................................................................... 161
SDI .................................................................................... 161
SDO .................................................................................. 161
SEC_IDLE Mode................................................................. 38
SEC_RUN Mode................................................................. 34
Serial Clock, SCK ............................................................. 161
Serial Data In (SDI)........................................................... 161
Serial Data Out (SDO) ...................................................... 161
Serial Peripheral Interface. See SPI Mode.
SETF................................................................................. 301
Slave Select (SS).............................................................. 161
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Slave Select Synchronization............................................ 167
SLEEP............................................................................... 302
Sleep
OSC1 and OSC2 Pin States ....................................... 31
Software Simulator (MPLAB SIM)..................................... 318
Special Event Trigger. See Compare (ECCP Mode).
Special Event Trigger. See Compare (ECCP Module).
Special Features of the CPU............................................. 249
Special Function Registers
Map ............................................................................. 63
SPI Mode (MSSP)
Associated Registers ................................................ 169
Bus Mode Compatibility ............................................ 169
Effects of a Reset...................................................... 169
Enabling SPI I/O ....................................................... 165
Master Mode ............................................................. 166
Master/Slave Connection .......................................... 165
Operation .................................................................. 164
Operation in Power-Managed Modes ....................... 169
Serial Clock............................................................... 161
Serial Data In ............................................................ 161
Serial Data Out ......................................................... 161
Slave Mode ............................................................... 167
Slave Select .............................................................. 161
Slave Select Synchronization ................................... 167
SPI Clock .................................................................. 166
Typical Connection ................................................... 165
SS ..................................................................................... 161
SSPOV.............................................................................. 191
SSPOV Status Flag........................................................... 191
SSPSTAT Register
R/W Bit .............................................................. 174, 175
Stack Full/Underflow Resets ............................................... 56
STATUS Register................................................................ 67
SUBFSR............................................................................ 313
SUBFWB........................................................................... 302
SUBLW ............................................................................. 303
SUBULNK ......................................................................... 313
SUBWF ............................................................................. 303
SUBWFB........................................................................... 304
SWAPF ............................................................................. 304
T
Table Pointer Operations with
TBLRD and TBLWT .................................................... 76
Table Reads/Table Writes................................................... 56
TBLRD .............................................................................. 305
TBLWT .............................................................................. 306
Time-out in Various Situations (table) ................................. 45
Timer0 ............................................................................... 123
Associated Registers ................................................ 125
Operation .................................................................. 124
Overflow Interrupt ..................................................... 125
Prescaler ................................................................... 125
Prescaler Assignment (PSA Bit) ............................... 125
Prescaler Select (T0PS2:T0PS0 Bits) ...................... 125
Prescaler. See Prescaler, Timer0.
Reads and Writes in 16-Bit Mode ............................. 124
Source Edge Select (T0SE Bit)................................. 124
Source Select (T0CS Bit) .......................................... 124
Switching Prescaler Assignment............................... 125
DS39631E-page 404
Timer1............................................................................... 127
16-Bit Read/Write Mode ........................................... 129
Associated Registers ................................................ 132
Considerations in Asynchronous
Counter Mode................................................... 131
Interrupt .................................................................... 130
Operation .................................................................. 128
Oscillator........................................................... 127, 129
Oscillator Layout Considerations .............................. 130
Overflow Interrupt ..................................................... 127
Resetting, Using the CCP Special
Event Trigger .................................................... 130
Special Event Trigger (ECCP) .................................. 148
TMR1H Register ....................................................... 127
TMR1L Register........................................................ 127
Use as a Real-Time Clock ........................................ 130
Timer2............................................................................... 133
Associated Registers ................................................ 134
Interrupt .................................................................... 134
Operation .................................................................. 133
Output ....................................................................... 134
PR2 Register .................................................... 144, 149
TMR2 to PR2 Match Interrupt........................... 144, 149
Timer3............................................................................... 135
16-Bit Read/Write Mode ........................................... 137
Associated Registers ................................................ 137
Operation .................................................................. 136
Oscillator........................................................... 135, 137
Overflow Interrupt ............................................. 135, 137
Special Event Trigger (CCP) .................................... 137
TMR3H Register ....................................................... 135
TMR3L Register........................................................ 135
Timing Diagrams
A/D Conversion......................................................... 360
Acknowledge Sequence ........................................... 194
Asynchronous Reception.......................................... 214
Asynchronous Transmission..................................... 212
Asynchronous Transmission (Back to Back) ............ 212
Automatic Baud Rate Calculation ............................. 210
Auto-Wake-up Bit (WUE) During
Normal Operation ............................................. 215
Auto-Wake-up Bit (WUE) During Sleep .................... 215
Baud Rate Generator with Clock Arbitration............. 188
BRG Overflow Sequence.......................................... 210
BRG Reset Due to SDA Arbitration
During Start Condition ...................................... 197
Brown-out Reset (BOR)............................................ 345
Bus Collision During a Repeated
Start Condition (Case 1) ................................... 198
Bus Collision During a Repeated
Start Condition (Case 2) ................................... 198
Bus Collision During a Start
Condition (SCL = 0) .......................................... 197
Bus Collision During a Stop
Condition (Case 1)............................................ 199
Bus Collision During a Stop
Condition (Case 2)............................................ 199
Bus Collision During Start
Condition (SDA only) ........................................ 196
Bus Collision for Transmit and Acknowledge ........... 195
Capture/Compare/PWM (All CCP Modules)............. 347
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
CLKO and I/O............................................................344
Clock Synchronization...............................................181
Clock/Instruction Cycle................................................57
EUSART Synchronous Receive
(Master/Slave)...................................................359
EUSART Synchronous Transmission
(Master/Slave)...................................................358
Example SPI Master Mode (CKE = 0).......................349
Example SPI Master Mode (CKE = 1).......................350
Example SPI Slave Mode (CKE = 0).........................351
Example SPI Slave Mode (CKE = 1).........................353
External Clock (All Modes Except PLL) ....................342
Fail-Safe Clock Monitor (FSCM) ...............................262
First Start Bit Timing..................................................189
Full-Bridge PWM Output ...........................................153
Half-Bridge PWM Output...........................................152
High/Low-Voltage Detect Characteristics..................339
High-Voltage Detect Operation (VDIRMAG = 1) .......246
I2C Bus Data .............................................................354
I2C Bus Start/Stop Bits..............................................354
I2C Master Mode (7 or 10-Bit Transmission).............192
I2C Master Mode (7-Bit Reception) ...........................193
I2C Slave Mode (10-Bit Reception, SEN = 0)............178
I2C Slave Mode (10-Bit Reception, SEN = 1)............183
I2C Slave Mode (10-Bit Transmission) ......................179
I2C Slave Mode (7-Bit Reception, SEN = 0)..............176
I2C Slave Mode (7-Bit Reception, SEN = 1)..............182
I2C Slave Mode (7-Bit Transmission) ........................177
I2C Slave Mode General Call Address
Sequence (7 or 10-Bit Addressing Mode) .........184
I2C Stop Condition Receive or Transmit Mode .........194
Low-Voltage Detect Operation (VDIRMAG = 0)........245
Master SSP I2C Bus Data .........................................356
Master SSP I2C Bus Start/Stop Bits..........................356
Parallel Slave Port (PIC18F4420/4520) ....................348
Parallel Slave Port (PSP) Read ................................121
Parallel Slave Port (PSP) Write.................................121
PWM Auto-Shutdown (PRSEN = 0,
Auto-Restart Disabled)......................................158
PWM Auto-Shutdown (PRSEN = 1,
Auto-Restart Enabled).......................................158
PWM Direction Change.............................................155
PWM Direction Change at Near
100% Duty Cycle...............................................155
PWM Output..............................................................144
Repeated Start Condition..........................................190
Reset, Watchdog Timer, Oscillator Start-up
Timer, Power-up Timer .....................................345
Send Break Character Sequence .............................216
Slave Synchronization...............................................167
Slow Rise Time (MCLR Tied to VDD,
VDD Rise > TPWRT) .............................................47
SPI Mode (Master Mode) ..........................................166
SPI Mode (Slave Mode, CKE = 0).............................168
SPI Mode (Slave Mode, CKE = 1).............................168
Synchronous Reception (Master Mode, SREN)........219
Synchronous Transmission .......................................217
Synchronous Transmission (Through TXEN) ...........218
Time-out Sequence on POR w/PLL Enabled
(MCLR Tied to VDD) ............................................47
Time-out Sequence on Power-up
(MCLR Not Tied to VDD, Case 1) ........................46
Time-out Sequence on Power-up
(MCLR Not Tied to VDD, Case 2) ........................46
DS39631E-page 405
Time-out Sequence on Power-up
(MCLR Tied to VDD, VDD Rise < TPWRT) ............ 46
Timer0 and Timer1 External Clock ........................... 346
Transition for Entry to Idle Mode................................. 38
Transition for Entry to SEC_RUN Mode ..................... 35
Transition for Entry to Sleep Mode ............................. 37
Transition for Two-Speed Start-up
(INTOSC to HSPLL) ......................................... 260
Transition for Wake from Idle to
Run Mode ........................................................... 38
Transition for Wake from Sleep (HSPLL) ................... 37
Transition from RC_RUN Mode to
PRI_RUN Mode .................................................. 36
Transition from SEC_RUN Mode to
PRI_RUN Mode (HSPLL) ................................... 35
Transition to RC_RUN Mode ...................................... 36
Timing Diagrams and Specifications................................. 342
A/D Conversion Requirements ................................. 360
Capture/Compare/PWM (CCP)
Requirements ................................................... 347
CLKO and I/O Requirements .................................... 344
EUSART Synchronous Receive
Requirements ................................................... 359
EUSART Synchronous Transmission
Requirements ................................................... 358
Example SPI Mode Requirements
(Master Mode, CKE = 0) ................................... 349
Example SPI Mode Requirements
(Master Mode, CKE = 1) ................................... 350
Example SPI Mode Requirements
(Slave Mode, CKE = 0) ..................................... 352
Example SPI Mode Requirements
(Slave Mode, CKE = 1) ..................................... 353
External Clock Requirements ................................... 342
I2C Bus Data Requirements (Slave Mode) ............... 355
Master SSP I2C Bus Data
Requirements ................................................... 357
Master SSP I2C Bus Start/Stop Bits
Requirements ................................................... 356
Parallel Slave Port Requirements
(PIC18F4420/4520) .......................................... 348
PLL Clock ................................................................. 343
Reset, Watchdog Timer, Oscillator Start-up
Timer, Power-up Timer and Brown-out
Reset Requirements ......................................... 345
Timer0 and Timer1 External Clock
Requirements ................................................... 346
Top-of-Stack Access........................................................... 54
TRISE Register
PSPMODE Bit........................................................... 114
TSTFSZ ............................................................................ 307
Two-Speed Start-up.................................................. 249, 260
Two-Word Instructions
Example Cases........................................................... 58
TXSTA Register
BRGH Bit .................................................................. 205
V
Voltage Reference Specifications ..................................... 338
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
W
X
Watchdog Timer (WDT) ............................................ 249, 258
Associated Registers ................................................ 259
Control Register ........................................................ 258
During Oscillator Failure ........................................... 261
Programming Considerations ................................... 258
WCOL ....................................................... 189, 190, 191, 194
WCOL Status Flag .................................... 189, 190, 191, 194
WWW Address.................................................................. 407
WWW, On-Line Support........................................................ 6
XORLW............................................................................. 307
XORWF ............................................................................ 308
DS39631E-page 406
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
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© 2008 Microchip Technology Inc.
DS39631E-page 407
PIC18F2420/2520/4420/4520
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: PIC18F2420/2520/4420/4520
Literature Number: DS39631E
Questions:
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DS39631E-page 408
© 2008 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
PIC18F2420/2520/4420/4520 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
PIC18F2420/2520(1), PIC18F4420/4520(1),
PIC18F2420/2520T(2), PIC18F4420/4520T(2);
VDD range 4.2V to 5.5V
PIC18LF2420/2520(1), PIC18LF4420/4520(1),
PIC18LF2420/2520T(2), PIC18LF4420/4520T(2);
VDD range 2.0V to 5.5V
Temperature Range
I
E
=
=
Package
PT
SO
SP
P
ML
=
=
=
=
=
Pattern
c)
PIC18LF4520-I/P 301 = Industrial temp., PDIP
package, Extended VDD limits, QTP pattern
#301.
PIC18LF2420-I/SO = Industrial temp., SOIC
package, Extended VDD limits.
PIC18F4420-I/P = Industrial temp., PDIP
package, normal VDD limits.
-40°C to +85°C (Industrial)
-40°C to +125°C (Extended)
TQFP (Thin Quad Flatpack)
SOIC
Skinny Plastic DIP
PDIP
QFN
Note 1:
2:
F = Standard Voltage Range
LF = Wide Voltage Range
T = in tape and reel TQFP
packages only.
QTP, SQTP, Code or Special Requirements
(blank otherwise)
© 2008 Microchip Technology Inc.
Advance Information
DS39631E-page 409
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Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
China - Nanjing
Tel: 86-25-8473-2460
Fax: 86-25-8473-2470
Malaysia - Kuala Lumpur
Tel: 60-3-6201-9857
Fax: 60-3-6201-9859
China - Qingdao
Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
Malaysia - Penang
Tel: 60-4-227-8870
Fax: 60-4-227-4068
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
Taiwan - Hsin Chu
Tel: 886-3-572-9526
Fax: 886-3-572-6459
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-536-4803
China - Xiamen
Tel: 86-592-2388138
Fax: 86-592-2388130
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
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 - Zhuhai
Tel: 86-756-3210040
Fax: 86-756-3210049
01/02/08
DS39631E-page 410
© 2008 Microchip Technology Inc.