MICROCHIP PIC16F720-E/ML

PIC16F/LF720/721
Data Sheet
20-Pin Flash Microcontrollers
with nanoWatt XLP Technology
 2010 Microchip Technology Inc.
DS41430A
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
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Information contained in this publication regarding device
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Trademarks
The Microchip name and logo, the Microchip logo, dsPIC,
KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART,
PIC32 logo, rfPIC and UNI/O are registered trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor,
MXDEV, MXLAB, SEEVAL and The Embedded Control
Solutions Company are registered trademarks of Microchip
Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, CodeGuard,
dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN,
ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial
Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified
logo, MPLIB, MPLINK, mTouch, Omniscient Code
Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit,
PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance,
TSHARC, UniWinDriver, WiperLock and ZENA are
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2010, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
ISBN: 978-1-60932-482-7
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.
DS41430A-page 2
 2010 Microchip Technology Inc.
PIC16F/LF720/721
20-Pin Flash Microcontrollers with nanoWatt XLP Technology
Devices Included In This Data Sheet:
• PIC16F720
• PIC16LF720
• PIC16F721
• PIC16LF721
High-Performance RISC CPU:
• Only 35 Instructions to Learn:
- All single-cycle instructions except branches
• Operating Speed:
- DC – 16 MHz oscillator/clock input
- DC – 250 ns instruction cycle
• Up to 4K x 14 Words of Flash Program Memory
• Up to 256 bytes of Data Memory (RAM)
• Interrupt Capability
• 8-Level Deep Hardware Stack
• Direct, Indirect and Relative Addressing modes
• Processor Self-Write/Read access to Program
Memory
Special Microcontroller Features:
• Precision Internal Oscillator:
- 16 MHz or 500 kHz operation
- Factory calibrated to ±1%, typical
- Software tunable
- Software selectable ÷1, ÷2, ÷4 or ÷8 divider
• Power-Saving Sleep mode
• Industrial and Extended Temperature Range
• Power-on Reset (POR)
• Power-up Timer (PWRT)
• Brown-out Reset (BOR)
• Multiplexed Master Clear with Pull-up/Input Pin
• Programmable Code Protection
• In-Circuit Serial ProgrammingTM (ICSPTM) via Two
Pins
• High-Endurance Flash Cell:
- 10,000 write Flash endurance (typical)
- Flash retention: > 40 years
• Wide Operating Voltage Range:
- 1.8V to 5.5V (PIC16F720/721)
- 1.8V to 3.6V (PIC16LF720/721)
 2010 Microchip Technology Inc.
Low-Power Features:
• Standby Current:
- 50 nA @ 1.8V, typical
• Operating Current:
- 100 A @ 500 kHz, 1.8V, typical
• Low-Power Watchdog Timer Current:
- 500 nA @ 1.8V, typical
Peripheral Features:
• Up to 17 I/O Pins and 1 Input-only Pin:
- High-current source/sink for direct LED drive
- Interrupt-on-pin change
- Individually programmable weak pull-ups
• A/D Converter:
- 8-bit resolution
- 12 channels
- Selectable Voltage reference
• Timer0: 8-Bit Timer/Counter with 8-Bit
Programmable Prescaler
• Enhanced Timer1
- 16-bit timer/counter with prescaler
- External Gate Input mode with toggle and
single shot modes
- Interrupt-on-gate completion
• Timer2: 8-Bit Timer/Counter with 8-Bit Period
Register, Prescaler and Postscaler
• Capture, Compare, PWM module (CCP)
- 16-bit Capture, max resolution 12.5 ns
- 16-bit Compare, max resolution 250 ns
- 10-bit PWM, max frequency 15 kHz
• Addressable Universal Synchronous
Asynchronous Receiver Transmitter (AUSART)
• Synchronous Serial Port (SSP)
- SPI (Master/Slave)
- I2CTM (Slave) with Address Mask
DS41430A-page 3
PIC16F/LF720/721
Device
PIC16F720
PIC16F721
PIC16LF720
PIC16LF721
DS41430A-page 4
Program
Memory
Flash
(words)
SRAM
(bytes)
I/O
Timers
8/16-bit
8-bit A/D
(ch)
AUSART
CCP
SSP
2048
4096
2048
4096
128
256
128
256
18
18
18
18
2/1
2/1
2/1
2/1
12
12
12
12
Yes
Yes
Yes
Yes
1
1
1
1
1
1
1
1
 2010 Microchip Technology Inc.
PIC16F/LF720/721
Pin Diagrams – 20-PIN DIAGRAM FOR PIC16F720/721 AND PIC16LF720/721
PDIP, SOIC, SSOP
VDD
1
20
VSS
2
19
RA0/AN0/ICSPDAT
3
18
RA1/AN1/ICSPCLK
RA3/MCLR/VPP
4
17
RA2/AN2/T0CKI/INT
RC5/CCP1
5
16
RC0/AN4
RC4
6
15
RC1/AN5
RC3/AN7
7
14
RC2/AN6
RC6/AN8/SS
8
13
RB4/AN10/SDI/SDA
RC7/AN9/SDO
9
12
RB5/AN11/RX/DT
10
11
RB6/SCK/SCL
RB7/TX/CK
PIC16F720/721
PIC16LF720/721
RA5/T1CKI/CLKIN
RA4/AN3/T1G/CLKOUT
RA0/AN0/ICSPDAT
VSS
VDD
20-Pin QFN (4x4)
RA5/T1CKI/CLKIN
RA4/AN3/T1G/CLKOUT
Pin Diagrams – 20-PIN DIAGRAM FOR PIC16F720/721 AND PIC16LF720/721
20 19 18 17 16
RC5/CCP1
2
RC4
3
RC3/AN7
4
14
PIC16F720/721
13
PIC16LF720/721
12
RC6/AN8/SS
5
11
 2010 Microchip Technology Inc.
7
8
9 10
RA1/AN1/ICSPCLK
RA2/AN2/T0CKI/INT
RC0/AN4
RC1/AN5
RC2/AN6
RB4/AN10/SDI/SDA
RC7/AN9/SDO
6
RB5/AN11/RX/DT
15
RB7/TX/CK
1
RB6/SCK/SCL
RA3/MCLR/VPP
DS41430A-page 5
PIC16F/LF720/721
20-Pin DIP/SOIC/
SSOP
20-Pin QFN
A/D
Timers
CCP
AUSART
SSP
Interrupt
Pull-up
Basic
20-PIN ALLOCATION TABLE (PIC16F720/721 AND PIC16LF720/721)
I/O
TABLE 1:
RA0
19
16
AN0
—
—
—
—
IOC
Y
ICSPDAT/
ICDDAT
RA1
18
15
AN1
—
—
—
—
IOC
Y
ICSPCLK/
ICDCLK
RA2
17
14
AN2
T0CKI
—
—
—
INT/IOC
—
—
RA3
4
1
—
—
—
—
—
IOC
Y
MCLR/VPP
RA4
3
20
AN3
T1G
—
—
—
IOC
Y
CLKOUT
RA5
2
19
—
T1CKI
—
—
—
IOC
Y
CLKIN
RB4
13
10
AN10
—
—
—
SDI/SDA
IOC
Y
—
RB5
12
9
AN11
—
—
RX/DT
—
IOC
Y
—
RB6
11
8
—
—
—
—
SCK/SCL
IOC
Y
—
RB7
10
7
—
—
—
TX/CK
—
IOC
Y
—
RC0
16
13
AN4
—
—
—
—
—
—
—
RC1
15
12
AN5
—
—
—
—
—
—
—
RC2
14
11
AN6
—
—
—
—
—
—
—
RC3
7
4
AN7
—
—
—
—
—
—
—
RC4
6
3
—
—
—
—
—
—
—
—
RC5
5
2
—
—
CCP1
—
—
—
—
—
RC6
8
5
AN8
—
—
—
SS
—
—
—
RC7
9
6
AN9
—
—
—
SDO
—
—
—
VDD
1
18
—
—
—
—
—
—
—
VDD
Vss
20
17
—
—
—
—
—
—
—
VSS
DS41430A-page 6
 2010 Microchip Technology Inc.
PIC16F/LF720/721
Table of Contents
1.0 Device Overview ......................................................................................................................................................................... 9
2.0 Memory Organization ................................................................................................................................................................ 13
3.0 Resets ....................................................................................................................................................................................... 27
4.0 Interrupts ................................................................................................................................................................................... 37
5.0 Low Dropout (LDO) Voltage Regulator ..................................................................................................................................... 45
6.0 I/O Ports .................................................................................................................................................................................... 47
7.0 Oscillator Module....................................................................................................................................................................... 67
8.0 Device Configuration ................................................................................................................................................................. 73
9.0 Analog-to-Digital Converter (ADC) Module ............................................................................................................................... 77
10.0 Fixed Voltage Reference........................................................................................................................................................... 87
11.0 Temperature Indicator Module ................................................................................................................................................... 89
12.0 Timer0 Module .......................................................................................................................................................................... 91
13.0 Timer1 Module with Gate Control.............................................................................................................................................. 95
14.0 Timer2 Module ........................................................................................................................................................................ 107
15.0 Capture/Compare/PWM (CCP) Module .................................................................................................................................. 109
16.0 Addressable Universal Synchronous Asynchronous Receiver Transmitter (AUSART) .......................................................... 119
17.0 SSP Module Overview ............................................................................................................................................................ 139
18.0 Flash Program Memory Self Read/Self Write Control............................................................................................................. 161
19.0 Power-Down Mode (Sleep) ..................................................................................................................................................... 169
20.0 In-Circuit Serial Programming™ (ICSP™) .............................................................................................................................. 171
21.0 Instruction Set Summary ......................................................................................................................................................... 173
22.0 Development Support.............................................................................................................................................................. 183
23.0 Electrical Specifications........................................................................................................................................................... 187
24.0 DC and AC Characteristics Graphs and Charts ...................................................................................................................... 213
25.0 Packaging Information............................................................................................................................................................. 225
Appendix A: Data Sheet Revision History......................................................................................................................................... 233
Appendix B: Migrating From Other PIC® Devices............................................................................................................................. 233
The Microchip Web Site .................................................................................................................................................................... 241
Customer Change Notification Service ............................................................................................................................................. 241
Customer Support ............................................................................................................................................................................. 241
Reader Response ............................................................................................................................................................................. 242
Product Identification System ............................................................................................................................................................ 243
 2010 Microchip Technology Inc.
DS41430A-page 7
PIC16F/LF720/721
TO OUR VALUED CUSTOMERS
It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip
products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and
enhanced as new volumes and updates are introduced.
If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via
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welcome your feedback.
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The last character of the literature number is the version number, (e.g., DS30000A is version A of document DS30000).
Errata
An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current
devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the revision
of silicon and revision of document to which it applies.
To determine if an errata sheet exists for a particular device, please check with one of the following:
• Microchip’s Worldwide Web site; http://www.microchip.com
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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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DS41430A-page 8
 2010 Microchip Technology Inc.
PIC16F/LF720/721
1.0
DEVICE OVERVIEW
The PIC16F/LF720/721 devices are covered by this
data sheet. They are available in 20-pin packages.
Figure 1-1 shows a block diagram of the
PIC16F/LF720/721 devices. Table 1-1 shows the pinout descriptions.
 2010 Microchip Technology Inc.
DS41430A-page 9
PIC16F/LF720/721
FIGURE 1-1:
20-PIN DEVICE BLOCK DIAGRAM FOR PIC16F720/721
PORTA
Configuration
13
Program Counter
Flash
4K x 14
8K
Program
Memory
(PIC16F720
2K x 14
Program
Bus
(PIC16F720
RAM
128 x 8)
File
Registers
368 x 8
256
8 Level Stack
(13-bit)
14
RA0
RA1
RA2
RA3
RA4
RA5
8
Data Bus
RAM Addr
PORTB
9
Addr MUX
Instruction
Instruction Reg
reg
7
Direct Addr
8
RB4
RB5
RB6
RB7
Indirect
Addr
FSR
FSR Reg
reg
STATUS
STATUS Reg
reg
8
3
PORTC
RC0
RC1
RC2
RC3
RC4
RC5
RC6
RC7
MUX
Power-up
Timer
Instruction
Decode &
Control
CLKIN
Timing
Generation
CLKOUT
Power-on
Reset
ALU
Watchdog
Timer
Brown-out
Reset
LDO
Regulator
8
W
W Reg
reg
Internal
Oscillator
Block
PMDATL
Self read/
write Flash
memory
MCLR VDD
VSS
EEADDR
CCP1
CCP1
T0CKI
Timer0
T1G
TX/CK RX/DT
ICSPDAT
ICSPCLK
AUSART
AUSART
ICSP™
SDI/ SCK/
SDO SDA SCL
SS
T1CKI
Timer1
Timer2
Synchronous
Serial Port
Analog-To-Digital Converter
AN0 AN1 AN2 AN3 AN4 AN5 AN6 AN7 AN8 AN9 AN10 AN11
DS41430A-page 10
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 1-1:
PINOUT DESCRIPTION
Name
Function
OUT
RA0
TTL
CMOS
AN0
AN
—
ICSPDAT
ST
CMOS
Serial mode Schmitt Trigger.
ICDDAT
ST
CMOS
Debug mode Schmitt Trigger.
RA1
TTL
CMOS
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
AN1
AN
—
A/D Channel 1 Input.
ICSPCLK
ST
—
Serial mode Schmitt Trigger.
ICDCLK
ST
CMOS
Debug mode Schmitt Trigger.
RA2
ST
CMOS
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
AN2
AN
—
A/D Channel 2 Input.
T0CKI
ST
—
Timer0 Clock Input.
INT
ST
—
RA0/AN0/ICSPDAT
RA1/AN1/ICSPCLK
RA2/AN2/T0CKI/INT
RA3/MCLR/VPP
RA4/AN3/T1G/CLKOUT
Legend:
A/D Channel 0 Input.
External interrupt.
General purpose input only. Individually controlled interrupt-onchange. Individually enabled pull-up.
TTL
CMOS
MCLR
ST
—
Master Clear Reset. Pull-up enabled when configured as
MCLR.
VPP
HV
—
Programming Voltage.
RA4
TTL
CMOS
AN3
AN
—
A/D Channel 3 Input.
T1G
ST
—
Timer1 Gate Input.
CLKOUT
—
CMOS
FOSC/4 output.
CMOS
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
RA5
RB5/AN11/RX/DT
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
RA3
RA5/T1CKI/CLKIN
RB4/AN10/SDI/SDA
Description
IN
TTL
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
T1CKI
ST
—
Timer1 Clock input.
CLKIN
ST
—
External Clock Input (EC mode).
RB4
TTL
CMOS
AN10
AN
—
SDI
ST
—
SPI Data Input.
SDA
ST
OD
I2C™ Data.
RB5
TTL
CMOS
AN11
AN
—
RX
ST
—
DT
ST
CMOS
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
A/D Channel 10 Input.
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
A/D Channel 11 Input.
USART asynchronous input.
USART synchronous data.
AN = Analog input or output, CMOS = CMOS compatible input or output, OD = Open Drain, TTL = TTL compatible
input, ST = Schmitt Trigger input with CMOS levels, I2C™ = Schmitt Trigger input with I2C, HV = High Voltage,
XTAL = Crystal levels
 2010 Microchip Technology Inc.
DS41430A-page 11
PIC16F/LF720/721
TABLE 1-1:
PINOUT DESCRIPTION
Name
Function
Description
IN
OUT
RB6
TTL
CMOS
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
SCK
ST
CMOS
SPI Clock.
SCL
ST
OD
RB7
TTL
CMOS
TX
—
CMOS
USART asynchronous transmit.
CK
ST
CMOS
USART synchronous clock.
RC0
ST
CMOS
General purpose I/O.
AN4
AN
—
A/D Channel 4 Input.
RC1
ST
CMOS
General purpose I/O.
AN5
AN
—
A/D Channel 5 Input.
RC2
ST
CMOS
General purpose I/O.
AN6
AN
—
A/D Channel 6 Input.
RC3
ST
CMOS
General purpose I/O.
AN7
AN
—
A/D Channel 7 Input.
RC4
RC4
ST
CMOS
General purpose I/O.
RC5/CCP1
RC5
ST
CMOS
General purpose I/O.
CCP1
ST
CMOS
Capture/Compare/PWM 1.
RC6
ST
CMOS
General purpose I/O.
AN8
AN
—
A/D Channel 8 Input.
SS
ST
—
Slave Select input.
RC7
ST
CMOS
AN9
AN
—
SDO
—
CMOS
VDD
Power
—
Positive supply.
Vss
Power
—
Ground supply.
RB6/SCK/SCL
RB7/TX/CK
RC0/AN4
RC1/AN5
RC2/AN6
RC3/AN7
RC6/AN8/SS
RC7/AN9/SDO
VDD
Vss
Legend:
I2C™ Clock.
General purpose I/O. Individually controlled interrupt-onchange.
Individually enabled pull-up.
General purpose I/O.
A/D Channel 9 Input.
SPI Data Output.
AN = Analog input or output, CMOS = CMOS compatible input or output, OD = Open Drain, TTL = TTL compatible
input, ST = Schmitt Trigger input with CMOS levels, I2C™ = Schmitt Trigger input with I2C, HV = High Voltage,
XTAL = Crystal levels
DS41430A-page 12
 2010 Microchip Technology Inc.
PIC16F/LF720/721
2.0
MEMORY ORGANIZATION
2.1
Program Memory Organization
The PIC16F720/LF720 has a 13-bit program counter
capable of addressing a 2K x 14 program memory
space (0000h-07FFh), a 4K x 14 program memory
space for the PIC16F721/LF721 (0000h-0FFFh).
Accessing a location above the memory boundaries for
the PIC16F720/LF720 will cause a wrap-around within
the first 2K x 14 program memory space. Accessing a
location above the memory boundaries for the
PIC16F721/LF721 will cause a wrap-around within the
first 4K x 14 program memory space. The Reset vector
is at 0000h and the interrupt vector is at 0004h.
FIGURE 2-1:
FIGURE 2-2:
PC<12:0>
CALL, RETURN
RETFIE, RETLW
CALL, RETURN
RETFIE, RETLW
Stack Level 8
On-chip
Program
Memory
13
13
Stack Level 1
Stack Level 2
PROGRAM MEMORY MAP
AND STACK FOR THE
PIC16F720/LF720
PC<12:0>
PROGRAM MEMORY MAP
AND STACK FOR THE
PIC16F721/LF721
Reset Vector
0000h
Interrupt Vector
0004H
0005h
Page 0
07FFh
0800h
Page 1
0FFFh
1000h
Stack Level 1
Stack Level 2
Wraps to Page 0
Stack Level 8
Wraps to Page 1
17FFh
1800h
1FFFh
On-chip
Program
Memory
Reset Vector
0000h
Interrupt Vector
0004H
0005h
Page 0
07FFh
0800h
Wraps to Page 0
0FFFh
1000h
Wraps to Page 0
17FFh
1800h
Wraps to Page 0
1FFFh
 2010 Microchip Technology Inc.
DS41430A-page 13
PIC16F/LF720/721
2.2
Data Memory Organization
The data memory is partitioned into multiple banks
which contain the General Purpose Registers (GPRs)
and the Special Function Registers (SFRs). Bits RP0
and RP1 are bank select bits.
RP1
RP0
0
0

Bank 0 is selected
0
1

Bank 1 is selected
1
0

Bank 2 is selected
1
1

Bank 3 is selected
Each bank extends up to 7Fh (128 bytes). The lower
locations of each bank are reserved for the Special
Function Registers. Above the Special Function
Registers are the General Purpose Registers,
implemented as static RAM. All implemented banks
contain Special Function Registers. Some frequently
used Special Function Registers from one bank are
mirrored in another bank for code reduction and
quicker access.
DS41430A-page 14
2.2.1
GENERAL PURPOSE REGISTER
FILE
The register file is organized as 128 x 8 bits in the
PIC16F720/LF720, 256 x 8 bits in the PIC16F721/
LF721. Each register is accessed either directly or
indirectly through the File Select Register (FSR), (Refer
to Section 2.5 “Indirect Addressing, INDF and FSR
Registers”).
2.2.2
SPECIAL FUNCTION REGISTERS
The Special Function Registers are registers used by
the CPU and peripheral functions for controlling the
desired operation of the device (refer to Table 2-1).
These registers are static RAM.
The Special Function Registers can be classified into
two sets: core and peripheral. The Special Function
Registers associated with the “core” are described in
this section. Those related to the operation of the
peripheral features are described in the section of that
peripheral feature.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 2-3:
PIC16F720/LF720 SPECIAL FUNCTION REGISTERS
File Address
Indirect addr.(*) 00h
Indirect addr.(*) 80h
Indirect addr.(*) 100h
Indirect addr.(*) 180h
TMR0
01h
OPTION_REG
81h
TMR0
101h
OPTION_REG
PCL
02h
PCL
82h
PCL
102h
PCL
181h
182h
STATUS
03h
STATUS
83h
STATUS
103h
STATUS
183h
FSR
104h
FSR
04h
FSR
84h
05h
TRISA
85h
105h
FSR
ANSELA
184h
PORTA
PORTB
06h
TRISB
86h
106h
ANSELB
186h
PORTC
07h
TRISC
87h
107h
ANSELC
187h
08h
88h
108h
09h
89h
109h
185h
188h
189h
PCLATH
0Ah
PCLATH
8Ah
PCLATH
10Ah
PCLATH
18Ah
INTCON
0Bh
INTCON
8Bh
INTCON
10Bh
INTCON
18Bh
0Ch
PIE1
8Ch
PMDATL
10Ch
PMCON1
18Ch
8Dh
PMADRL
10Dh
PMCON2
18Dh
PIR1
0Dh
TMR1L
0Eh
PCON
8Eh
PMDATH
10Eh
18Eh
TMR1H
0Fh
T1GCON
8Fh
PMADRH
10Fh
18Fh
T1CON
10h
OSCCON
90h
110h
190h
TMR2
11h
OSCTUNE
91h
111h
191h
T2CON
12h
PR2
92h
112h
192h
SSPBUF
13h
SSPADD/SSPMSK 93h
113h
193h
SSPCON
14h
SSPSTAT
94h
114h
194h
CCPR1L
15h
WPUA
95h
WPUB
115h
195h
CCPR1H
16h
IOCA
96h
IOCB
116h
196h
CCP1CON
17h
97h
117h
197h
RCSTA
18h
TXSTA
98h
118h
198h
TXREG
19h
SPBRG
99h
119h
199h
RCREG
1Ah
9Ah
11Ah
19Ah
1Bh
9Bh
11Bh
19Bh
1Ch
9Ch
11Ch
19Ch
9Dh
11Dh
19Dh
9Eh
11Eh
19Eh
9Fh
11Fh
19Fh
A0h
120h
1A0h
EFh
16Fh
1EFh
F0h
170h
1F0h
1Dh
ADRES
1Eh
ADCON0
1Fh
FVRCON
ADCON1
20h
General
Purpose
Register
32 Bytes
General
Purpose
Register
96 Bytes
BFh
C0h
Accesses
70h – 7Fh
7Fh
BANK 0
Legend:
*
Accesses
70h – 7Fh
FFh
BANK 1
Accesses
70h – 7Fh
17Fh
BANK 2
1FFh
BANK 3
= Unimplemented data memory locations, read as ‘0’.
= Not a physical register.
 2010 Microchip Technology Inc.
DS41430A-page 15
PIC16F/LF720/721
FIGURE 2-4:
PIC16F721/LF721 SPECIAL FUNCTION REGISTERS
File Address
Indirect addr.(*)
00h
Indirect addr.(*)
80h
Indirect addr.(*)
100h
Indirect addr.(*)
180h
TMR0
01h
OPTION_REG
81h
TMR0
101h
OPTION_REG
181h
PCL
02h
PCL
82h
PCL
102h
PCL
182h
STATUS
03h
STATUS
83h
STATUS
103h
STATUS
183h
FSR
104h
FSR
04h
FSR
84h
05h
TRISA
85h
105h
FSR
ANSELA
184h
PORTA
PORTB
06h
TRISB
86h
106h
ANSELB
186h
PORTC
07h
TRISC
87h
107h
ANSELC
187h
88h
108h
08h
09h
PCLATH
89h
188h
109h
10Ah
189h
0Ah
PCLATH
8Ah
INTCON
0Bh
INTCON
8Bh
INTCON
10Bh
INTCON
18Bh
PIR1
0Ch
PIE1
8Ch
PMDATL
10Ch
PMCON1
18Ch
8Dh
PMADRL
10Dh
PMCON2
18Dh
TMR1L
0Eh
PCON
8Eh
PMDATH
10Eh
18Eh
TMR1H
0Fh
T1GCON
8Fh
PMADRH
10Fh
18Fh
T1CON
10h
OSCCON
90h
110h
190h
TMR2
11h
OSCTUNE
91h
111h
191h
T2CON
12h
PR2
92h
112h
192h
SSPBUF
13h
SSPADD/SSPMSK 93h
113h
193h
SSPCON
14h
SSPSTAT
94h
114h
194h
0Dh
PCLATH
185h
PCLATH
18Ah
CCPR1L
15h
WPUA
95h
WPUB
115h
195h
CCPR1H
16h
IOCA
96h
IOCB
116h
196h
CCP1CON
17h
97h
117h
197h
RCSTA
18h
TXSTA
98h
118h
198h
TXREG
19h
SPBRG
99h
119h
199h
RCREG
1Ah
9Ah
11Ah
19Ah
1Bh
9Bh
11Bh
19Bh
1Ch
9Ch
11Ch
19Ch
9Dh
11Dh
19Dh
9Eh
11Eh
19Eh
9Fh
11Fh
19Fh
A0h
120h
1A0h
16Fh
1EFh
1Dh
ADRES
1Eh
ADCON0
1Fh
20h
General
Purpose
Register
96 Bytes
FVRCON
ADCON1
General
Purpose
Register
80 Bytes
Accesses
70h – 7Fh
Legend:
*
F0h
Accesses
70h – 7Fh
FFh
7Fh
BANK 0
EFh
General
Purpose
Register
80 Bytes
BANK 1
170h
Accesses
70h – 7Fh
17Fh
BANK 2
1F0h
1FFh
BANK 3
= Unimplemented data memory locations, read as ‘0’.
= Not a physical register.
DS41430A-page 16
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 2-1:
Address
SPECIAL FUNCTION REGISTER SUMMARY
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on all
other
Resets
Bank 0
00h( 2)
INDF
Addressing this location uses contents of FSR to address data memory (not a physical register)
xxxx xxxx
xxxx xxxx
01h
TMR0
Timer0 module Register
xxxx xxxx
uuuu uuuu
02h( 2)
PCL
Program Counter (PC) Least Significant Byte
0000 0000
0000 0000
03h( 2)
STATUS
000q quuu
04h( 2)
FSR
05h
PORTA
IRP
RP1
RP0
—
—
RA5
TO
PD
Z
DC
C
0001 1xxx
xxxx xxxx
uuuu uuuu
RA2
RA1
RA0
--xx xxxx
--xx xxxx
Indirect Data Memory Address Pointer
RA4
RA3
06h
PORTB
RB7
RB6
RB5
RB4
—
—
—
—
xxxx ----
uuuu ----
07h
PORTC
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
xxxx xxxx
uuuu uuuu
—
08h
—
Unimplemented
—
09h
—
Unimplemented
—
—
Write Buffer for the upper 5 bits of the Program Counter
---0 0000
---0 0000
0Ah( 1),( 2)
PCLATH
0Bh( 2)
INTCON
0Ch
PIR1
0Dh
—
0Eh
TMR1L
0Fh
TMR1H
10h
T1CON
11h
TMR2
12h
T2CON
13h
SSPBUF
14h
SSPCON
15h
CCPR1L
16h
CCPR1H
17h
CCP1CON
18h
RCSTA
19h
TXREG
1Ah
RCREG
—
—
—
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
Unimplemented
—
—
Holding Register for the Least Significant Byte of the 16-bit TMR1 Register
xxxx xxxx
uuuu uuuu
xxxx xxxx
uuuu uuuu
0000 -0-0
uuuu -u-u
Holding Register for the Most Significant Byte of the 16-bit TMR1 Register
TMR1CS1
TMR1CS0
T1CKPS1
T1CKPS0
—
T1SYNC
—
TMR1ON
Timer2 module Register
—
TOUTPS3
WCOL
SSPOV
0000 0000
0000 0000
-000 0000
-000 0000
xxxx xxxx
uuuu uuuu
0000 0000
0000 0000
Capture/Compare/PWM Register Low Byte
xxxx xxxx
uuuu uuuu
Capture/Compare/PWM Register High Byte
xxxx xxxx
uuuu uuuu
TOUTPS2
TOUTPS1
TOUTPS0
TMR2ON
T2CKPS1 T2CKPS0
Synchronous Serial Port Receive Buffer/Transmit Register
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
—
—
DC1
B1
CCP1M3
CCP1M2
CCP1M1
CCP1M0
--00 0000
--00 0000
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
AUSART Transmit Data Register
0000 0000
0000 0000
AUSART Receive Data Register
0000 0000
0000 0000
1Bh
—
Unimplemented
—
—
1Ch
—
Unimplemented
—
—
1Dh
—
Unimplemented
—
—
ADC Result Register
xxxx xxxx
uuuu uuuu
--00 0000
--00 0000
1Eh
ADRES
1Fh
ADCON0
Legend:
Note 1:
2:
3:
4:
5:
—
—
CHS3
CHS2
CHS1
CHS0
GO/
DONE
ADON
x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved.
Shaded locations are unimplemented, read as ‘0’.
The upper byte of the program counter is not directly accessible. PCLATH is a holding register for the PC<12:8>, whose contents are transferred to the
upper byte of the program counter.
These registers can be addressed from any bank.
Accessible only when SSPM<3:0> = 1001.
This bit is unimplemented and reads as ‘1’.
See Register 6-2.
 2010 Microchip Technology Inc.
DS41430A-page 17
PIC16F/LF720/721
TABLE 2-1:
Address
SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED)
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on all
other
Resets
Bank 1
80h( 2)
INDF
81h
OPTION_
REG
82h( 2)
PCL
83h( 2)
STATUS
84h( 2)
FSR
85h(5)
TRISA
86h
TRISB
TRISB7
TRISB6
TRISB5
TRISB4
—
—
87h
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
88h
—
89h
—
8Ah( 1),( 2)
Addressing this location uses contents of FSR to address data memory (not a physical register)
RABPU
INTEDG
T0CS
IRP
RP1
RP0
—
—
TRISA5
xxxx xxxx
xxxx xxxx
PS1
PS0
1111 1111
1111 1111
0000 0000
0000 0000
Z
DC
C
0001 1xxx
000q quuu
xxxx xxxx
uuuu uuuu
TRISA2
TRISA1
TRISA0
--11 -111
--11 -111
—
—
1111 ----
1111 ----
TRISC1
TRISC0
1111 1111
1111 1111
Unimplemented
—
—
Unimplemented
—
—
Write Buffer for the upper 5 bits of the Program Counter
---0 0000
---0 0000
T0SE
PSA
PS2
Program Counter (PC) Least Significant Byte
TO
PD
Indirect Data Memory Address Pointer
PCLATH
8Bh( 2)
INTCON
8Ch
PIE1
8Dh
—
8Eh
PCON
8Fh
—
TRISA4
Note 4
—
—
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
Unimplemented
—
—
—
—
—
—
—
—
POR
BOR
---- --qq
---- --uu
T1GCON
TMR1GE
T1GPOL
T1GTM
T1GSPM
T1GGO/
DONE
T1GVAL
T1GSS1
T1GSS0
0000 0x00
uuuu uxuu
90h
OSCCON
—
—
IRCF1
IRCF0
ICSL
ICSS
—
—
--10 qq--
--10 qq--
91h
OSCTUNE
—
—
TUN5
TUN4
TUN3
TUN2
TUN1
TUN0
--00 0000
--uu uuuu
92h
PR2
Timer2 module Period Register
1111 1111
1111 1111
93h
SSPADD
ADD<7:0>
0000 0000
0000 0000
93h( 3)
SSPMSK
MSK<7:0>
1111 1111
1111 1111
94h
SSPSTAT
95h
96h
SMP
CKE
D/A
P
S
R/W
UA
BF
0000 0000
0000 0000
WPUA
—
—
WPUA5
WPUA4
WPUA3
WPUA2
WPUA1
WPUA0
--11 1111
--11 1111
IOCA
—
—
IOCA5
IOCA4
IOCA3
IOCA2
IOCA1
IOCA0
--00 0000
--00 0000
97h
—
98h
TXSTA
CSRC
TX9
TXEN
99h
SPBRG
BRG7
BRG6
BRG5
Unimplemented
—
—
SYNC
—
BRGH
TRMT
TX9D
0000 -010
0000 -010
BRG4
BRG3
BRG2
BRG1
BRG0
0000 0000
0000 0000
9Ah
—
Unimplemented
—
—
9Bh
—
Unimplemented
—
—
9Ch
—
Unimplemented
—
—
q000 --00
9Dh
FVRCON
9Eh
FVRRDY
FVREN
TSEN
TSRNG
—
ADCS2
ADCS1
ADCS0
—
9Fh
ADCON1
Legend:
Note 1:
2:
3:
4:
5:
—
—
ADFVR1
ADFVR0
q000 --00
—
—
—
—
—
—
-000 ----
-000 ----
Unimplemented
x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved.
Shaded locations are unimplemented, read as ‘0’.
The upper byte of the program counter is not directly accessible. PCLATH is a holding register for the PC<12:8>, whose contents are transferred to the
upper byte of the program counter.
These registers can be addressed from any bank.
Accessible only when SSPM<3:0> = 1001.
This bit is unimplemented and reads as ‘1’.
See Register 6-2.
DS41430A-page 18
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 2-1:
Address
SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED)
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on all
other
Resets
Bank 2
100h( 2)
INDF
Addressing this location uses contents of FSR to address data memory (not a physical register)
xxxx xxxx
xxxx xxxx
101h
TMR0
Timer0 module Register
xxxx xxxx
uuuu uuuu
102h( 2)
PCL
Program Counter (PC) Least Significant Byte
0000 0000
0000 0000
103h( 2)
STATUS
0001 1xxx
000q quuu
104h( 2)
FSR
IRP
RP1
RP0
TO
PD
Z
DC
C
Indirect Data Memory Address Pointer
xxxx xxxx
uuuu uuuu
105h
—
Unimplemented
—
—
106h
—
Unimplemented
—
—
107h
—
Unimplemented
—
—
108h
—
Unimplemented
—
—
109h
—
Unimplemented
—
—
---0 0000
---0 0000
10Ah( 1),( 2) PCLATH
—
—
GIE
PEIE
—
Write Buffer for the upper 5 bits of the Program Counter
10Bh( 2)
INTCON
0000 000x
0000 000x
10Ch
PMDATL
Program Memory Read Data Register Low Byte
xxxx xxxx
xxxx xxxx
10Dh
PMADRL
Program Memory Read Address Register Low Byte
0000 0000
0000 0000
10Eh
PMDATH
—
—
--xx xxxx
--xx xxxx
10Fh
PMADRH
—
—
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
Program Memory Read Data Register High Byte
—
Program Memory Read Address Register High Byte
---0 0000
---0 0000
110h
—
Unimplemented
—
—
111h
—
Unimplemented
—
—
112h
—
Unimplemented
—
—
113h
—
Unimplemented
—
—
114h
—
Unimplemented
—
—
115h
WPUB
WPUB7
WPUB6
WPUB5
WPUB4
—
—
—
—
1111 ----
1111 ----
116h
IOCB
IOCB7
IOCB6
IOCB5
IOCB4
—
—
—
—
0000 ----
0000 ----
117h
—
Unimplemented
—
—
118h
—
Unimplemented
—
—
119h
—
Unimplemented
—
—
11Ah
—
Unimplemented
—
—
11Bh
—
Unimplemented
—
—
11Ch
—
Unimplemented
—
—
11Dh
—
Unimplemented
—
—
11Eh
—
Unimplemented
—
—
11Fh
—
Unimplemented
—
—
Legend:
Note 1:
2:
3:
4:
5:
x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved.
Shaded locations are unimplemented, read as ‘0’.
The upper byte of the program counter is not directly accessible. PCLATH is a holding register for the PC<12:8>, whose contents are transferred to the
upper byte of the program counter.
These registers can be addressed from any bank.
Accessible only when SSPM<3:0> = 1001.
This bit is unimplemented and reads as ‘1’.
See Register 6-2.
 2010 Microchip Technology Inc.
DS41430A-page 19
PIC16F/LF720/721
TABLE 2-1:
Address
SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED)
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on all
other
Resets
Bank 3
180h( 2)
INDF
181h
OPTION_
REG
182h( 2)
PCL
183h( 2)
STATUS
Addressing this location uses contents of FSR to address data memory (not a physical register)
RABPU
INTEDG
T0CS
T0SE
IRP
RP1
RP0
—
—
—
ANSA4
PSA
xxxx xxxx
xxxx xxxx
PS1
PS0
1111 1111
1111 1111
0000 0000
0000 0000
Z
DC
C
0001 1xxx
000q quuu
xxxx xxxx
uuuu uuuu
ANSA2
ANSA1
ANSA0
---1 -111
---1 -111
PS2
Program Counter (PC) Least Significant Byte
TO
PD
184h( 2)
FSR
185h
ANSELA
186h
ANSELB
—
—
ANSB5
ANSB4
—
—
—
—
--11 ----
--11 ----
187h
ANSELC
ANSC7
ANSC6
—
—
ANSC3
ANSC2
ANSC1
ANSC0
11-- 1111
11-- 1111
—
—
—
188h
Indirect Data Memory Address Pointer
—
18Ah( 1),( 2) PCLATH
—
Unimplemented
Write Buffer for the upper 5 bits of the Program Counter
—
—
---0 0000
---0 0000
18Bh( 2)
INTCON
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
18Ch
PMCON1
—(4)
CFGS
LWLO
FREE
—
WREN
WR
RD
1000 -000
1000 -000
18Dh
PMCON2
Program Memory Control Register 2 (not a physical register)
---- ----
---- ----
190h
—
Unimplemented
—
—
191h
—
Unimplemented
—
—
192h
—
Unimplemented
—
—
193h
—
Unimplemented
—
—
194h
—
Unimplemented
—
—
195h
—
Unimplemented
—
—
196h
—
Unimplemented
—
—
197h
—
Unimplemented
—
—
198h
—
Unimplemented
—
—
199h
—
Unimplemented
—
—
19Ah
—
Unimplemented
—
—
19Bh
—
Unimplemented
—
—
19Ch
—
Unimplemented
—
—
19Dh
—
Unimplemented
—
—
19Eh
—
Unimplemented
—
—
19Fh
—
Unimplemented
—
—
Legend:
Note 1:
2:
3:
4:
5:
x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved.
Shaded locations are unimplemented, read as ‘0’.
The upper byte of the program counter is not directly accessible. PCLATH is a holding register for the PC<12:8>, whose contents are transferred to the
upper byte of the program counter.
These registers can be addressed from any bank.
Accessible only when SSPM<3:0> = 1001.
This bit is unimplemented and reads as ‘1’.
See Register 6-2.
DS41430A-page 20
 2010 Microchip Technology Inc.
PIC16F/LF720/721
2.2.2.1
STATUS Register
The STATUS register, shown in Register 2-1, contains:
• the arithmetic status of the ALU
• the Reset status
• the bank select bits for data memory (SRAM)
The STATUS register can be the destination for any
instruction, like any other register. If the STATUS
register is the destination for an instruction that affects
the Z, DC or C bits, then the write to these three bits is
disabled. These bits are set or cleared according to the
device logic. Furthermore, the TO and PD bits are not
writable. Therefore, the result of an instruction with the
STATUS register as destination may be different than
intended.
REGISTER 2-1:
R/W-0
It is recommended, therefore, that only BCF, BSF,
SWAPF and MOVWF instructions are used to alter the
STATUS register, because these instructions do not
affect any Status bits. For other instructions not
affecting any Status bits (Refer to Section 21.0
“Instruction Set Summary”).
Note 1: The C and DC bits operate as Borrow
and Digit Borrow out bits, respectively, in
subtraction.
STATUS: STATUS REGISTER
R/W-0
IRP
For example, CLRF STATUS will clear the upper three
bits and set the Z bit. This leaves the STATUS register
as ‘000u u1uu’ (where u = unchanged).
RP1
R/W-0
RP0
R-1
TO
R-1
PD
R/W-x
R/W-x
R/W-x
Z
DC(1)
C(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
IRP: Register Bank Select bit (used for indirect addressing)
1 = Bank 2, 3 (100h-1FFh)
0 = Bank 0, 1 (00h-FFh)
bit 6-5
RP<1:0>: Register Bank Select bits (used for direct addressing)
00 = Bank 0 (00h-7Fh)
01 = Bank 1 (80h-FFh)
10 = Bank 2 (100h-17Fh)
11 = Bank 3 (180h-1FFh)
bit 4
TO: Time-out bit
1 = After power-up, CLRWDT instruction or SLEEP instruction
0 = A WDT time-out occurred
bit 3
PD: Power-down bit
1 = After power-up or by the CLRWDT instruction
0 = By execution of the SLEEP instruction
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/Digit Borrow bit (ADDWF, ADDLW,SUBLW,SUBWF instructions)(1)
1 = A carry-out from the 4th low-order bit of the result occurred
0 = No carry-out from the 4th low-order bit of the result
bit 0
C: Carry/Borrow bit(1) (ADDWF, ADDLW, SUBLW, SUBWF instructions)(1)
1 = A carry-out from the Most Significant bit of the result occurred
0 = No carry-out from the Most Significant bit of the result occurred
Note 1:
For Borrow, the polarity is reversed. A subtraction is executed by adding the two’s complement of the
second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high-order or low-order
bit of the source register.
 2010 Microchip Technology Inc.
DS41430A-page 21
PIC16F/LF720/721
2.2.2.2
OPTION register
Note:
The OPTION register, shown in Register 2-2, is a
readable and writable register, which contains various
control bits to configure:
• Software programmable prescaler for the Timer0/
WDT
• External RA2/INT interrupt
• Timer0
• Weak pull-ups on PORTA or PORTB
REGISTER 2-2:
To achieve a 1:1 prescaler assignment for
Timer0, assign the prescaler to the WDT
by setting the PSA bit of the OPTION
register to ‘1’. Refer to Section 12.1.3
“Software Programmable Prescaler”.
OPTION_REG: OPTION 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
RABPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
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
RABPU: PORTA or PORTB Pull-up Enable bit
1 = PORTA or PORTB pull-ups are disabled
0 = PORTA or PORTB pull-ups are enabled by individual bits in the WPUB register
bit 6
INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of RA2/INT pin
0 = Interrupt on falling edge of RA2/INT pin
bit 5
T0CS: Timer0 Clock Source Select bit
1 = Transition on RA2/T0CKI pin
0 = Internal instruction cycle clock (FOSC/4)
bit 4
T0SE: Timer0 Source Edge Select bit
1 = Increment on high-to-low transition on RA2/T0CKI pin
0 = Increment on low-to-high transition on RA2/T0CKI pin
bit 3
PSA: Prescaler Assignment bit
1 = Prescaler is assigned to the WDT
0 = Prescaler is assigned to the Timer0 module
bit 2-0
PS<2:0>: Prescaler Rate Select bits
Bit Value
000
001
010
011
100
101
110
111
DS41430A-page 22
Timer0 Rate
1:2
1:4
1:8
1 : 16
1 : 32
1 : 64
1 : 128
1 : 256
WDT Rate
1:1
1:2
1:4
1:8
1 : 16
1 : 32
1 : 64
1 : 128
 2010 Microchip Technology Inc.
PIC16F/LF720/721
2.2.2.3
PCON Register
The Power Control (PCON) register contains flag bits
(refer to Table 3-4) to differentiate between a:
•
•
•
•
Power-on Reset (POR)
Brown-out Reset (BOR)
Watchdog Timer Reset (WDT)
External MCLR Reset
The PCON register also controls the software enable of
the BOR.
The PCON register bits are shown in Register 2-3.
REGISTER 2-3:
PCON: POWER CONTROL REGISTER
U-0
U-0
U-0
U-0
U-0
U-0
R/W-q
R/W-q
—
—
—
—
—
—
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
q = Value depends on condition
bit 7-2
Unimplemented: Read as ‘0’
bit 1
POR: Power-on Reset Status bit
1 = No Power-on Reset occurred
0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs)
bit 0
BOR: Brown-out Reset Status bit
1 = No Brown-out Reset occurred
0 = A Brown-out Reset occurred (must be set in software after a Power-on Reset or Brown-out Reset
occurs)
 2010 Microchip Technology Inc.
DS41430A-page 23
PIC16F/LF720/721
2.3
PCL and PCLATH
The Program Counter (PC) is 13 bits wide. The low
byte comes from the PCL register, which is a readable
and writable register. The high byte (PC<12:8>) is not
directly readable or writable and comes from
PCLATH. On any Reset, the PC is cleared. Figure 2-5
shows the two situations for the loading of the PC. The
upper example in Figure 2-5 shows how the PC is
loaded on a write to PCL (PCLATH<4:0>  PCH).
The lower example in Figure 2-5 shows how the PC is
loaded during a CALL or GOTO instruction
(PCLATH<4:3>  PCH).
FIGURE 2-5:
LOADING OF PC IN
DIFFERENT SITUATIONS
PCH
12
PCL
8 7
0
PC
8
PCLATH<4:0>
5
Instruction with
PCL as
Destination
ALU Result
PCLATH
PCH
12 11 10
PCL
8 7
0
PC
GOTO, CALL
2
PCLATH<4:3>
11
Note 1: There are no Status bits to indicate stack
overflow or stack underflow conditions.
2: There are no instructions/mnemonics
called PUSH or POP. These are actions
that occur from the execution of the
CALL, RETURN, RETLW and RETFIE
instructions or the vectoring to an
interrupt address.
2.4
Program Memory Paging
All devices are capable of addressing a continuous 8K
word block of program memory. The CALL and GOTO
instructions provide only 11 bits of address to allow
branching within any 2K program memory page. When
doing a CALL or GOTO instruction, the upper 2 bits of
the address are provided by PCLATH<4:3>. When
doing a CALL or GOTO instruction, the user must ensure
that the page select bits are programmed so that the
desired program memory page is addressed. If a return
from a CALL instruction (or interrupt) is executed, the
entire 13-bit PC is POPed off the stack. Therefore,
manipulation of the PCLATH<4:3> bits is not required
for the RETURN instructions (which POPs the address
from the stack).
Note:
The contents of the PCLATH register are
unchanged after a RETURN or RETFIE
instruction is executed. The user must
rewrite the contents of the PCLATH register for any subsequent subroutine calls or
GOTO instructions.
Opcode<10:0>
PCLATH
2.3.1
COMPUTED GOTO
A computed GOTO is accomplished by adding an offset
to the program counter (ADDWF PCL). When performing a table read using a computed GOTO method, care
should be exercised if the table location crosses a PCL
memory boundary (each 256-byte block). Refer to the
Application Note AN556, “Implementing a Table Read”
(DS00556).
2.3.2
Example 2-1 shows the calling of a subroutine in
page 1 of the program memory. This example assumes
that PCLATH is saved and restored by the Interrupt
Service Routine (if interrupts are used).
EXAMPLE 2-1:
ORG 500h
PAGESEL SUB_P1 ;Select page 1
;(800h-FFFh)
CALL
SUB1_P1 ;Call subroutine in
:
;page 1 (800h-FFFh)
:
ORG
900h
;page 1 (800h-FFFh)
STACK
All devices have an 8-level x 13-bit wide hardware
stack (refer to Figures 2-1 and 2-2). The stack space is
not part of either program or data space and the Stack
Pointer is not readable or writable. The PC is PUSHed
onto the stack when a CALL instruction is executed or
an interrupt causes a branch. The stack is POPed in
the event of a RETURN, RETLW or a RETFIE instruction
execution. PCLATH is not affected by a PUSH or POP
operation.
The stack operates as a circular buffer. This means that
after the stack has been PUSHed eight times, the ninth
PUSH overwrites the value that was stored from the
first PUSH. The tenth PUSH overwrites the second
PUSH (and so on).
DS41430A-page 24
CALL OF A SUBROUTINE
IN PAGE 1 FROM PAGE 0
SUB1_P1
:
:
RETURN
;called subroutine
;page 1 (800h-FFFh)
;return to
;Call subroutine
;in page 0
;(000h-7FFh)
 2010 Microchip Technology Inc.
PIC16F/LF720/721
2.5
EXAMPLE 2-2:
Indirect Addressing, INDF and
FSR Registers
INDIRECT ADDRESSING
MOVLW020h ;initialize pointer
MOVWFFSR
;to RAM
BANKISEL020h
NEXTCLRFINDF
;clear INDF register
INCFFSR
;inc pointer
BTFSSFSR,4 ;all done?
GOTONEXT
;no clear next
CONTINUE
;yes continue
The INDF register is not a physical register. Addressing
the INDF register will cause indirect addressing.
Indirect addressing is possible by using the INDF
register. Any instruction using the INDF register
actually accesses data pointed to by the File Select
Register (FSR). Reading INDF itself indirectly will
produce 00h. Writing to the INDF register indirectly
results in a no operation (although Status bits may be
affected). An effective 9-bit address is obtained by
concatenating the 8-bit FSR register and the IRP bit of
the STATUS register, as shown in Figure 2-6.
A simple program to clear RAM location 020h-02Fh
using indirect addressing is shown in Example 2-2.
FIGURE 2-6:
DIRECT/INDIRECT ADDRESSING
Direct Addressing
RP1
RP0 6
Bank Select
From Opcode
Indirect Addressing
0
7
IRP
Bank Select
Location Select
00
01
10
File Select Register0
Location Select
11
00h
180h
Data
Memory
7Fh
1FFh
Bank 0
Note:
Bank 1
Bank 2
Bank 3
For memory map detail, refer to Figures 2-3 and 2-4.
 2010 Microchip Technology Inc.
DS41430A-page 25
PIC16F/LF720/721
NOTES:
DS41430A-page 26
 2010 Microchip Technology Inc.
PIC16F/LF720/721
3.0
RESETS
The PIC16F/LF720/721 differentiates between various
kinds of Reset:
a)
b)
c)
d)
e)
f)
Power-on Reset (POR)
WDT Reset during normal operation
WDT Reset during Sleep
MCLR Reset during normal operation
MCLR Reset during Sleep
Brown-out Reset (BOR)
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 3-1.
Some registers are not affected in any Reset condition;
their status is unknown on POR and unchanged in any
other Reset. Most other registers are reset to a “Reset
state” on:
•
•
•
•
•
Most registers are not affected by a WDT wake-up
since this is viewed as the resumption of normal
operation. TO and PD bits are set or cleared differently
in different Reset situations, as indicated in Table 3-5.
These bits are used in software to determine the nature
of the Reset.
The MCLR Reset path has a noise filter to detect and
ignore small pulses. See Section 23.0 “Electrical
Specifications” for pulse width specifications.
Power-on Reset (POR)
MCLR Reset
MCLR Reset during Sleep
WDT Reset
Brown-out Reset (BOR)
FIGURE 3-1:
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
MCLRE
MCLR/VPP
Sleep
WDT
Module
WDT
Time-out
Reset
POR
Power-on Reset
VDD
Brown-out(1)
Reset
BOREN
OST/PWRT
OST
Chip_Reset
10-bit Ripple Counter
OSC1/
CLKIN
PWRT
WDTOSC
11-bit Ripple Counter
Enable PWRT
Enable OST
Note
1:
Refer to the Configuration Word Register 1 (Register 8-1).
 2010 Microchip Technology Inc.
DS41430A-page 27
PIC16F/LF720/721
TABLE 3-1:
STATUS BITS AND THEIR SIGNIFICANCE
POR
BOR
TO
PD
0
x
1
1
Power-on Reset or LDO Reset
0
x
0
x
Illegal, TO is set on POR
0
x
x
0
Illegal, PD is set on POR
1
0
1
1
Brown-out Reset
1
1
0
1
WDT Reset
1
1
0
0
WDT Wake-up
1
1
u
u
MCLR Reset during normal operation
1
1
1
0
MCLR Reset during Sleep or interrupt wake-up from Sleep
TABLE 3-2:
Condition
RESET CONDITION FOR SPECIAL REGISTERS(2)
Program
Counter
STATUS
Register
PCON
Register
Power-on Reset
0000h
0001 1xxx
---- --0x
MCLR Reset during normal operation
0000h
000u uuuu
---- --uu
MCLR Reset during Sleep
0000h
0001 0uuu
---- --uu
WDT Reset
0000h
0000 1uuu
---- --uu
WDT Wake-up
PC + 1
uuu0 0uuu
---- --uu
0000h
0001 1uuu
---- --u0
PC + 1(1)
uuu1 0uuu
---- --uu
Condition
Brown-out Reset
Interrupt Wake-up from Sleep
Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’.
Note 1: When the wake-up is due to an interrupt and Global Interrupt Enable bit (GIE) is set, the return address is
pushed on the stack and PC is loaded with the interrupt vector (0004h) after execution of PC + 1.
2: If a Status bit is not implemented, that bit will be read as ‘0’.
DS41430A-page 28
 2010 Microchip Technology Inc.
PIC16F/LF720/721
3.1
MCLR
3.3
The PIC16F/LF720/721 has a noise filter in the MCLR
Reset path. The filter will detect and ignore small
pulses.
It should be noted that a Reset does not drive the
MCLR pin low.
Voltages applied to the pin that exceed its specification
can result in both MCLR Resets and excessive current
beyond the device specification during the ESD event.
For this reason, Microchip recommends that the MCLR
pin no longer be tied directly to VDD. The use of an RC
network, as shown in Figure 3-2, is suggested.
An internal MCLR option is enabled by clearing the
MCLRE bit in the Configuration Word register. When
MCLRE = 0, the Reset signal to the chip is generated
internally. When the MCLRE = 1, the RA3/MCLR pin
becomes an external Reset input. In this mode, the
RA3/MCLR pin has a weak pull-up to VDD. In-Circuit
Serial Programming™ is not affected by selecting the
internal MCLR option.
The Power-up Timer provides a fixed 72 ms (nominal)
time out on power-up only, from POR or Brown-out
Reset. The Power-up Timer operates from the WDT
oscillator. For more information, see Section 7.3
“Internal Clock Modes”. The chip is kept in Reset as
long as PWRT is active. The PWRT delay allows the
VDD to rise to an acceptable level. A Configuration bit,
PWRTE, can disable (if set) or enable (if cleared or programmed) the Power-up Timer. The Power-up Timer
should be enabled when Brown-out Reset is enabled,
although it is not required.
The Power-up Timer delay will vary from chip-to-chip
and vary due to:
• VDD variation
• Temperature variation
• Process variation
See DC parameters for details
“Electrical Specifications”).
Note:
FIGURE 3-2:
RECOMMENDED MCLR
CIRCUIT
VDD
®
PIC MCU
R1
10 k
MCLR
C1
0.1 F
3.4
Power-on Reset (POR)
(Section 23.0
The Power-up Timer is enabled by the
PWRTE bit in the Configuration Word.
Watchdog Timer (WDT)
The WDT has the following features:
• Shares an 8-bit prescaler with Timer0
• Time-out period is from 17 ms to 2.2 seconds,
nominal
• Enabled by a Configuration bit
WDT is cleared under certain conditions described in
Table 3-3.
3.4.1
3.2
Power-up Timer (PWRT)
WDT OSCILLATOR
The WDT derives its time base from 31 kHz internal
oscillator.
The on-chip POR circuit holds the chip in Reset until VDD
has reached a high enough level for proper operation. A
maximum rise time for VDD is required. See
Section 23.0 “Electrical Specifications” for details. If
the BOR is enabled, the maximum rise time specification
does not apply. The BOR circuitry will keep the device in
Reset until VDD reaches VBOR (see Section 3.5
“Brown-Out Reset (BOR)”).
When the device starts normal operation (exits the
Reset condition), device operating parameters (i.e.,
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.
For additional information, refer to Application Note
AN607, “Power-up Trouble Shooting” (DS00607).
 2010 Microchip Technology Inc.
DS41430A-page 29
PIC16F/LF720/721
3.4.2
WDT CONTROL
The WDTE bit is located in the Configuration Word
Register 1. When set, the WDT runs continuously.
The PSA and PS<2:0> bits of the OPTION register
control the WDT period. See Section 12.0 “Timer0
Module” for more information.
FIGURE 3-1:
WATCHDOG TIMER BLOCK DIAGRAM
T1GSS = 11
TMR1GE
From TMR0
Clock Source
WDTE
Low-Power
WDT OSC
0
Divide by
512
Postscaler
1
8
PS<2:0>
TO TMR0
PSA
0
1
WDT Reset
To T1G
WDTE
TABLE 3-3:
WDT STATUS
Conditions
WDTE = 0
WDT
Cleared
CLRWDT Command
Exit Sleep + System Clock = INTOSC, EXTCLK
DS41430A-page 30
 2010 Microchip Technology Inc.
PIC16F/LF720/721
3.5
Brown-Out Reset (BOR)
Brown-out Reset is enabled by programming the
BOREN<1:0> bits in the Configuration register.
Between the POR and BOR, complete voltage range
coverage for execution protection can be
implemented.
Two bits are used to enable the BOR. When
BOREN = 11, the BOR is always enabled. When
BOREN = 10, the BOR is enabled, but disabled during
Sleep. When BOREN = 0X, the BOR is disabled.
If VDD falls below VBOR for greater than parameter
(TBOR) (see Section 23.0 “Electrical Specifications”), the Brown-out situation will reset the device.
This will occur regardless of VDD slew rate. A Reset is
not ensured to occur if VDD falls below VBOR for more
than parameter (TBOR).
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 re-initialized. Once VDD
rises above VBOR, the Power-up Timer will execute a
64 ms Reset.
FIGURE 3-3:
BROWN-OUT SITUATIONS
VDD
Internal
Reset
VBOR
64 ms(1)
VDD
Internal
Reset
VBOR
< 64 ms
64 ms(1)
VDD
Internal
Reset
Note 1:
VBOR
64 ms(1)
64 ms delay only if PWRTE bit is programmed to ‘0’.
 2010 Microchip Technology Inc.
DS41430A-page 31
PIC16F/LF720/721
3.6
Time-out Sequence
3.7
On power-up, the time-out sequence is as follows: first,
PWRT time-out is invoked after POR has expired, then
OST is activated after the PWRT time-out has expired.
The total time-out will vary based on oscillator configuration and PWRTE bit status. For example, in EC mode
with PWRTE bit = 1 (PWRT disabled), there will be no
time-out at all. Figure 3-4, Figure 3-5 and Figure 3-6
depict time-out sequences.
The Power Control (PCON) register has two Status bits
to indicate what type of Reset that last occurred.
Bit 0 is BOR (Brown-out Reset). BOR is unknown on
Power-on Reset. It must then be set by the user and
checked on subsequent Resets to see if BOR = 0,
indicating that a Brown-out has occurred. The BOR
Status bit is a “don’t care” and is not necessarily
predictable if the brown-out circuit is disabled
(BOREN<1:0> = 00 in the Configuration Word register).
Since the time-outs occur from the POR pulse, if MCLR
is kept low long enough, the time-outs will expire. Then,
bringing MCLR high will begin execution immediately
(see Figure 3-5). This is useful for testing purposes or
to synchronize more than one PIC16F/LF720/721
device operating in parallel.
Bit 1 is POR (Power-on Reset). It is a ‘0’ on Power-on
Reset and unaffected otherwise. The user must write a
‘1’ to this bit following a Power-on Reset. On a
subsequent Reset, if POR is ‘0’, it will indicate that a
Power-on Reset has occurred (i.e., VDD may have
gone too low).
Table 3-5 shows the Reset conditions for some special
registers.
TABLE 3-4:
Power Control (PCON) Register
For more information, see Section 3.5 “Brown-Out
Reset (BOR)”.
TIME-OUT IN VARIOUS SITUATIONS
Power-up
Brown-out Reset
PWRTE = 0
PWRTE = 1
PWRTE = 0
PWRTE = 1
Wake-up from
Sleep
TPWRT
—
TPWRT
—
—
Oscillator Configuration
EC, INTOSC
TABLE 3-5:
RESET BITS AND THEIR SIGNIFICANCE
POR
BOR
TO
PD
Condition
0
u
1
1
Power-on Reset
1
0
1
1
Brown-out Reset
u
u
0
u
WDT Reset
u
u
0
0
WDT Wake-up
u
u
u
u
MCLR Reset during normal operation
u
u
1
0
MCLR Reset during Sleep
Legend: u = unchanged, x = unknown
FIGURE 3-4:
TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 1
VDD
MCLR
Internal POR
TPWRT
PWRT Time-out
TOST
Internal Reset
DS41430A-page 32
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 3-5:
TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 2
VDD
MCLR
Internal POR
TPWRT
PWRT Time-out
TOST
Internal Reset
FIGURE 3-6:
TIME-OUT SEQUENCE ON POWER-UP (MCLR WITH VDD): CASE 3
VDD
MCLR
Internal POR
TPWRT
PWRT Time-out
TOST
Internal Reset
 2010 Microchip Technology Inc.
DS41430A-page 33
PIC16F/LF720/721
TABLE 3-6:
INITIALIZATION CONDITION FOR REGISTERS
Register
W
Address
Power-on Reset/
Brown-out Reset(1)
MCLR Reset/
WDT Reset
Wake-up from Sleep through
Interrupt/Time-out
—
xxxx xxxx
uuuu uuuu
uuuu uuuu
INDF
00h/80h/
100h/180h
xxxx xxxx
xxxx xxxx
uuuu uuuu
TMR0
01h/101h
xxxx xxxx
uuuu uuuu
uuuu uuuu
PCL
02h/82h/
102h/182h
0000 0000
0000 0000
PC + 1(3)
STATUS
03h/83h/
103h/183h
0001 1xxx
000q quuu(4)
uuuq quuu(4)
FSR
04h/84h/
104h/184h
xxxx xxxx
uuuu uuuu
uuuu uuuu
PORTA
05h
--xx xxxx
--xx xxxx
--uu uuuu
PORTB
06h
xxxx ----
xxxx ----
uuuu ----
PORTC
07h
xxxx xxxx
xxxx xxxx
uuuu uuuu
PCLATH
0Ah/8Ah/
10Ah/18Ah
---0 0000
---0 0000
---u uuuu
INTCON
0Bh/8Bh/
10Bh/18Bh
0000 000x
0000 000x
uuuu uuuu(2)
PIR1
0Ch
0000 0000
0000 0000
uuuu uuuu(2)
TMR1L
0Eh
xxxx xxxx
uuuu uuuu
uuuu uuuu
TMR1H
0Fh
xxxx xxxx
uuuu uuuu
uuuu uuuu
T1CON
10h
0000 -0-0
0000 -0-0
uuuu -u-u
TMR2
11h
0000 0000
0000 0000
uuuu uuuu
T2CON
12h
-000 0000
-000 0000
-uuu uuuu
SSPBUF
13h
xxxx xxxx
xxxx xxxx
uuuu uuuu
SSPCON
14h
0000 0000
0000 0000
uuuu uuuu
CCPR1L
15h
xxxx xxxx
xxxx xxxx
uuuu uuuu
CCPR1H
16h
xxxx xxxx
xxxx xxxx
uuuu uuuu
CCP1CON
17h
--00 0000
--00 0000
--uu uuuu
RCSTA
18h
0000 000x
0000 000x
uuuu uuuu
TXREG
19h
0000 0000
0000 0000
uuuu uuuu
RCREG
1Ah
0000 0000
0000 0000
uuuu uuuu
ADRES
1Eh
xxxx xxxx
uuuu uuuu
uuuu uuuu
ADCON0
1Fh
--00 0000
--00 0000
--uu uuuu
81h/181h
1111 1111
1111 1111
uuuu uuuu
85h
--11 -111
--11 -111
--uu -uuu
TRISB
86h
1111 ----
1111 ----
uuuu ----
TRISC
87h
1111 1111
1111 1111
uuuu uuuu
8Ch
0000 0000
0000 0000
uuuu uuuu
OPTION_REG
TRISA
PIE1
Legend:
Note 1:
2:
3:
4:
5:
u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’, q = value depends on condition.
If VDD goes too low, Power-on Reset will be activated and registers will be affected differently.
One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up).
When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt
vector (0004h).
See Table 3-8 for Reset value for specific condition.
If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u.
DS41430A-page 34
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 3-6:
INITIALIZATION CONDITION FOR REGISTERS (CONTINUED)
Address
Power-on Reset/
Brown-out Reset(1)
PCON
8Eh
---- --qq
---- --uu(1,5)
---- --uu
T1GCON
8Fh
0000 0x00
uuuu uxuu
uuuu uxuu
OSCCON
90h
--10 qq--
--10 qq--
--uu qq--
OSCTUNE
91h
--00 0000
--uu uuuu
--uu uuuu
PR2
92h
1111 1111
1111 1111
uuuu uuuu
SSPADD
93h
0000 0000
0000 0000
uuuu uuuu
SSPMSK
93h
1111 1111
1111 1111
uuuu uuuu
SSPSTAT
94h
0000 0000
0000 0000
uuuu uuuu
WPUB
115h
1111 ----
1111 ----
uuuu ----
WPUA
95h
--11 1111
--11 1111
--uu uuuu
IOCB
116h
0000 ----
0000 ----
uuuu ----
IOCA
96h
--00 0000
--00 0000
--uu uuuu
TXSTA
98h
0000 -010
0000 -010
uuuu -uuu
SPBRG
99h
0000 0000
0000 0000
uuuu uuuu
FVRCON
9Dh
q000 --00
q000 --00
uuuu --uu
ADCON1
9Fh
-000 ----
-000 ----
-uuu ----
PMDATL
10Ch
xxxx xxxx
xxxx xxxx
uuuu uuuu
PMADRL
10Dh
0000 0000
0000 0000
uuuu uuuu
PMDATH
10Eh
--xx xxxx
--xx xxxx
--uu uuuu
PMADRH
10Fh
---0 0000
---0 0000
---u uuuu
ANSELA
185h
---1 -111
---1 -111
---u -uuu
ANSELB
186h
--11 ----
--11 ----
--uu ----
ANSELC
187h
11-- 1111
11-- 1111
uu-- uuuu
18Ch
1000 -000
1000 -000
1000 -000
Register
PMCON1
Legend:
Note 1:
2:
3:
4:
5:
MCLR Reset/
WDT Reset
Wake-up from Sleep through
Interrupt/Time-out
u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’, q = value depends on condition.
If VDD goes too low, Power-on Reset will be activated and registers will be affected differently.
One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up).
When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt
vector (0004h).
See Table 3-8 for Reset value for specific condition.
If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u.
 2010 Microchip Technology Inc.
DS41430A-page 35
PIC16F/LF720/721
TABLE 3-7:
INITIALIZATION CONDITION FOR SPECIAL REGISTERS
Program
Counter
STATUS
Register
PCON
Register
Power-on Reset
0000h
0001 1xxx
---- --0x
MCLR Reset during normal operation
0000h
000u uuuu
---- --uu
MCLR Reset during Sleep
0000h
0001 0uuu
---- --uu
WDT Reset
0000h
0000 uuuu
---- --uu
WDT Wake-up
PC + 1
uuu0 0uuu
---- --uu
Brown-out Reset
0000h
0001 1xxx
---- --10
uuu1 0uuu
---- --uu
Condition
Interrupt Wake-up from Sleep
PC + 1
(1)
Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’.
Note 1: When the wake-up is due to an interrupt and Global Interrupt Enable bit (GIE) is set, the PC is loaded with
the interrupt vector (0004h) after execution of PC + 1.
TABLE 3-8:
SUMMARY OF REGISTERS ASSOCIATED WITH RESETS
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets(1)
STATUS
IRP
RP1
RP0
TO
PD
Z
DC
C
0001 1xxx
000q quuu
—
—
—
—
—
—
POR
BOR
---- --qq
---- --uu
PCON
Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’, q = value depends on condition.
Shaded cells are not used by Resets.
Note 1: Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation.
DS41430A-page 36
 2010 Microchip Technology Inc.
PIC16F/LF720/721
4.0
INTERRUPTS
The PIC16F/LF720/721 device family features an
interruptible core, allowing certain events to preempt
normal program flow. An Interrupt Service Routine
(ISR) is used to determine the source of the interrupt
and act accordingly. Some interrupts can be configured
to wake the MCU from Sleep mode.
The PIC16F/LF720/721 device family has 12 interrupt
sources, differentiated by corresponding interrupt
enable and flag bits:
•
•
•
•
•
•
•
•
•
•
•
Timer0 Overflow Interrupt
External Edge Detect on INT Pin Interrupt
PORTA and PORTB Change Interrupt
Timer1 Gate Interrupt
A/D Conversion Complete Interrupt
AUSART Receive Interrupt
AUSART Transmit Interrupt
SSP Event Interrupt
CCP1 Event Interrupt
Timer2 Match with PR2 Interrupt
Timer1 Overflow Interrupt
A block diagram of the interrupt logic is shown in
Figure 4-1.
FIGURE 4-1:
INTERRUPT LOGIC
IOC-RB4
IOCB4
IOC-RB5
IOCB5
IOC-RB6
IOCB6
IOC-RB7
IOCB7
IOC-RA0
IOCA0
IOC-RA1
IOCA1
IOC-RA2
IOCA2
IOC-RA3
IOCA3
IOC-RA4
IOCA4
IOC-RA5
IOCA5
 2010 Microchip Technology Inc.
SSPIF
SSPIE
TXIF
TXIE
RCIF
RCIE
TMR2IF
TMR2IE
TMR1IF
TMR1IE
ADIF
ADIE
TMR1GIF
TMR1GIE
Wake-up (if in Sleep mode)(1)
TMR0IF
TMR0IE
Interrupt to CPU
INTF
INTE
RABIF
RABIE
PEIE
GIE
CCP1IF
CCP1IE
Note 1:
Some peripherals depend upon the
system clock for operation. Since the
system clock is suspended during
Sleep, these peripherals will not wake
the part from Sleep. See Section 19.1
“Wake-up from Sleep”.
DS41430A-page 37
PIC16F/LF720/721
4.1
Operation
interrupts. Because the GIE bit is cleared, any interrupt
that occurs while executing the ISR will be recorded
through its Interrupt Flag, but will not cause the
processor to redirect to the interrupt vector.
Interrupts are disabled upon any device Reset. They
are enabled by setting the following bits:
• GIE bit of the INTCON register
• Interrupt Enable bit(s) for the specific interrupt
event(s)
• PEIE bit of the INTCON register (if the Interrupt
Enable bit of the interrupt event is contained in the
PIE1 register)
The RETFIE instruction exits the ISR by popping the
previous address from the stack and setting the GIE bit.
For additional information on a specific interrupt’s
operation, refer to its peripheral chapter.
Note 1: Individual interrupt flag bits are set,
regardless of the state of any other
enable bits.
The INTCON and PIR1 registers record individual
interrupts via interrupt flag bits. Interrupt flag bits will be
set, regardless of the status of the GIE, PEIE and
individual Interrupt Enable bits.
2: All interrupts will be ignored while the GIE
bit is cleared. Any interrupt occurring
while the GIE bit is clear will be serviced
when the GIE bit is set again.
The following events happen when an interrupt event
occurs while the GIE bit is set:
• Current prefetched instruction is flushed
• GIE bit is cleared
• Current Program Counter (PC) is pushed onto the
stack
• PC is loaded with the interrupt vector 0004h
4.2
Interrupt latency is defined as the time from when the
interrupt event occurs to the time code execution at the
interrupt vector begins. The latency for synchronous
interrupts is 3 instruction cycles. For asynchronous
interrupts, the latency is 3 to 4 instruction cycles,
depending on when the interrupt occurs. See Figure 4-2
for timing details.
The ISR determines the source of the interrupt by
polling the interrupt flag bits. The interrupt flag bits must
be cleared before exiting the ISR to avoid repeated
FIGURE 4-2:
Interrupt Latency
INT PIN INTERRUPT TIMING
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
OSC1
CLKOUT (3)
(4)
INT pin
(1)
(1)
INTF flag
(INTCON<1>)
Interrupt Latency (2)
(5)
GIE bit
(INTCON<7>)
INSTRUCTION FLOW
PC
Instruction
Fetched
Instruction
Executed
Note 1:
PC
Inst (PC)
Inst (PC – 1)
PC + 1
Inst (PC + 1)
Inst (PC)
PC + 1
—
Dummy Cycle
0004h
0005h
Inst (0004h)
Inst (0005h)
Dummy Cycle
Inst (0004h)
INTF flag is sampled here (every Q1).
2:
Asynchronous interrupt latency = 3-4 TCY. Synchronous latency = 3 TCY, where TCY = instruction cycle time. Latency
is the same whether Inst (PC) is a single cycle or a 2-cycle instruction.
3:
CLKOUT is available only in INTOSC and RC Oscillator modes.
4:
For minimum width of INT pulse, refer to AC specifications in Section 23.0 “Electrical Specifications”.
5:
INTF is enabled to be set any time during the Q4-Q1 cycles.
DS41430A-page 38
 2010 Microchip Technology Inc.
PIC16F/LF720/721
4.3
Interrupts During Sleep
Some interrupts can be used to wake from Sleep. To
wake from Sleep, the peripheral must be able to
operate without the system clock. The interrupt source
must have the appropriate Interrupt Enable bit(s) set
prior to entering Sleep.
On waking from Sleep, if the GIE bit is also set, the
processor will branch to the interrupt vector. Otherwise,
the processor will continue executing instructions after
the SLEEP instruction. The instruction directly after the
SLEEP instruction will always be executed before
branching to the ISR. Refer to the Section 19.0
“Power-Down Mode (Sleep)” for more details.
4.4
INT Pin
The external interrupt, INT pin, causes an
asynchronous, edge-triggered interrupt. The INTEDG bit
of the OPTION register determines on which edge the
interrupt will occur. When the INTEDG bit is set, the
rising edge will cause the interrupt. When the INTEDG
bit is clear, the falling edge will cause the interrupt. The
INTF bit of the INTCON register will be set when a valid
edge appears on the INT pin. If the GIE and INTE bits
are also set, the processor will redirect program
execution to the interrupt vector. This interrupt is
disabled by clearing the INTE bit of the INTCON register.
4.5
Context Saving
When an interrupt occurs, only the return PC value is
saved to the stack. If the ISR modifies or uses an
instruction that modifies key registers, their values
must be saved at the beginning of the ISR and restored
when the ISR completes. This prevents instructions
EXAMPLE 4-1:
following the ISR from using invalid data. Examples of
key registers include the W, STATUS, FSR and
PCLATH registers.
Note:
The microcontroller does not normally
require saving the PCLATH register.
However, if computed GOTOs are used,
the PCLATH register must be saved at the
beginning of the ISR and restored when
the ISR is complete to ensure correct
program flow.
The code shown in Example 4-1 can be used to do the
following.
•
•
•
•
•
•
•
Save the W register
Save the STATUS register
Save the PCLATH register
Execute the ISR program
Restore the PCLATH register
Restore the STATUS register
Restore the W register
Since most instructions modify the W register, it must
be saved immediately upon entering the ISR. The
SWAPF instruction is used when saving and restoring
the W and STATUS registers because it will not affect
any bits in the STATUS register. It is useful to place
W_TEMP in shared memory because the ISR cannot
predict which bank will be selected when the interrupt
occurs.
The processor will branch to the interrupt vector by
loading the PC with 0004h. The PCLATH register will
remain unchanged. This requires the ISR to ensure
that the PCLATH register is set properly before using
an instruction that causes PCLATH to be loaded into
the PC. See Section 2.3 “PCL and PCLATH” for
details on PC operation.
SAVING W, STATUS AND PCLATH REGISTERS IN RAM
MOVWFW_TEMP
SWAPFSTATUS,W
;Copy W to W_TEMP register
;Swap status to be saved into W
;Swaps are used because they do not affect the status bits
BANKSELSTATUS_TEMP ;Select regardless of current bank
MOVWFSTATUS_TEMP ;Copy status to bank zero STATUS_TEMP register
MOVF
PCLATH,W ;Copy PCLATH to W register
MOVWF
PCLATH_TEMP
;Copy W register to PCLATH_TEMP
:
:(ISR)
;Insert user code here
:
BANKSELSTATUS_TEMP ;Select regardless of current bank
MOVF
PCLATH_TEMP,W;
MOVWF
PCLATH
;Restore PCLATH
SWAPFSTATUS_TEMP,W ;Swap STATUS_TEMP register into W
;(sets bank to original state)
MOVWFSTATUS
;Move W into STATUS register
SWAPFW_TEMP,F
;Swap W_TEMP
SWAPFW_TEMP,W
;Swap W_TEMP into W
 2010 Microchip Technology Inc.
DS41430A-page 39
PIC16F/LF720/721
4.5.1
INTCON REGISTER
Note:
The INTCON register is a readable and writable
register, which contains the various enable and flag bits
for TMR0 register overflow, PORTB change and
external RA2/INT pin interrupts.
REGISTER 4-1:
R/W-0
INTCON: INTERRUPT CONTROL REGISTER
R/W-0
GIE
Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the Global
Interrupt Enable bit, GIE of the INTCON
register. User software should ensure the
appropriate interrupt flag bits are clear
prior to enabling an interrupt.
PEIE
R/W-0
TMR0IE
R/W-0
R/W-0
INTE
RABIE(1)
R/W-0
TMR0IF
(2)
R/W-0
R/W-x
INTF
RABIF
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: Global Interrupt Enable bit
1 = Enables all unmasked interrupts
0 = Disables all interrupts
bit 6
PEIE: Peripheral Interrupt Enable bit
1 = Enables all unmasked peripheral interrupts
0 = Disables all peripheral interrupts
bit 5
TMR0IE: Timer0 Overflow Interrupt Enable bit
1 = Enables the Timer0 interrupt
0 = Disables the Timer0 interrupt
bit 4
INTE: RA2/INT External Interrupt Enable bit
1 = Enables the RA2/INT external interrupt
0 = Disables the RA2/INT external interrupt
bit 3
RABIE: PORTA or PORTB Change Interrupt Enable bit(1)
1 = Enables the PORTA or PORTB change interrupt
0 = Disables the PORTA or PORTB change interrupt
bit 2
TMR0IF: Timer0 Overflow Interrupt Flag bit(2)
1 = TMR0 register has overflowed (must be cleared in software)
0 = TMR0 register did not overflow
bit 1
INTF: RA2/INT External Interrupt Flag bit
1 = The RA2/INT external interrupt occurred (must be cleared in software)
0 = The RA2/INT external interrupt did not occur
bit 0
RABIF: PORTA or PORTB Change Interrupt Flag bit
1 = When at least one of the PORTA or PORTB general purpose I/O pins changed state (must be
cleared in software)
0 = None of the PORTA or PORTB general purpose I/O pins have changed state
Note 1:
2:
The appropriate bits in the IOCB register must also be set.
TMR0IF bit is set when Timer0 rolls over. Timer0 is unchanged on Reset and should be initialized before
clearing TMR0IF bit.
DS41430A-page 40
 2010 Microchip Technology Inc.
PIC16F/LF720/721
4.5.2
PIE1 REGISTER
The PIE1 register contains the interrupt enable bits, as
shown in Register 4-2.
REGISTER 4-2:
Note:
Bit PEIE of the INTCON register must be
set to enable any peripheral interrupt.
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
R/W-0
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
TMR1GIE: Timer1 Gate Interrupt Enable bit
1 = Enable the Timer1 gate acquisition complete interrupt
0 = Disable the Timer1 gate acquisition complete interrupt
bit 6
ADIE: A/D Converter (ADC) Interrupt Enable bit
1 = Enables the ADC interrupt
0 = Disables the ADC interrupt
bit 5
RCIE: USART Receive Interrupt Enable bit
1 = Enables the USART receive interrupt
0 = Disables the USART receive interrupt
bit 4
TXIE: USART Transmit Interrupt Enable bit
1 = Enables the USART transmit interrupt
0 = Disables the USART transmit interrupt
bit 3
SSPIE: Synchronous Serial Port (SSP) Interrupt Enable bit
1 = Enables the SSP interrupt
0 = Disables the SSP 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 Timer2 to PR2 match interrupt
0 = Disables the Timer2 to PR2 match interrupt
bit 0
TMR1IE: Timer1 Overflow Interrupt Enable bit
1 = Enables the Timer1 overflow interrupt
0 = Disables the Timer1 overflow interrupt
 2010 Microchip Technology Inc.
x = Bit is unknown
DS41430A-page 41
PIC16F/LF720/721
4.5.3
PIR1 REGISTER
The PIR1 register contains the interrupt flag bits, as
shown in Register 4-3.
REGISTER 4-3:
Note:
Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the Global
Interrupt Enable bit, GIE of the INTCON
register. User software should ensure the
appropriate interrupt flag bits are clear prior
to enabling an interrupt.
PIR1: PERIPHERAL INTERRUPT REQUEST REGISTER 1
R/W-0
R/W-0
R-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
TMR1GIF
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
TMR1GIF: Timer1 Gate Interrupt Flag bit
1 = Timer1 gate is inactive
0 = Timer1 gate is active
bit 6
ADIF: A/D Converter Interrupt Flag bit
1 = A/D conversion complete (must be cleared in software)
0 = A/D conversion has not completed or has not been started
bit 5
RCIF: USART Receive Interrupt Flag bit
1 = The USART receive buffer is full (cleared by reading RCREG)
0 = The USART receive buffer is not full
bit 4
TXIF: USART Transmit Interrupt Flag bit
1 = The USART transmit buffer is empty (cleared by writing to TXREG)
0 = The USART transmit buffer is full
bit 3
SSPIF: Synchronous Serial Port (SSP) 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: Timer2 to PR2 Interrupt Flag bit
1 = A Timer2 to PR2 match occurred (must be cleared in software)
0 = No Timer2 to PR2 match occurred
bit 0
TMR1IF: Timer1 Overflow Interrupt Flag bit
1 = The TMR1 register overflowed (must be cleared in software)
0 = The TMR1 register did not overflow
DS41430A-page 42
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 4-1:
Name
INTCON
SUMMARY OF REGISTERS ASSOCIATED WITH INTERRUPTS
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x 0000 000x
RABPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
1111 1111 1111 1111
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE TMR1IE 0000 0000 0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF TMR1IF 0000 0000 0000 0000
OPTION_REG
Legend: - = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the Capture,
Compare and PWM.
 2010 Microchip Technology Inc.
DS41430A-page 43
PIC16F/LF720/721
NOTES:
DS41430A-page 44
 2010 Microchip Technology Inc.
PIC16F/LF720/721
5.0
LOW DROPOUT (LDO)
VOLTAGE REGULATOR
The PIC16F720/721 devices differ from the
PIC16LF720/721 devices due to an internal Low
Dropout (LDO) voltage regulator. The PIC16F720/721
contain an internal LDO, while the PIC16LF720/721 do
not.
The lithography of the die allows a maximum operating
voltage of 3.6V on the internal digital logic. In order to
continue to support 5.0V designs, a LDO voltage
regulator is integrated on the die. The LDO voltage
regulator allows for the internal digital logic to operate
at 3.2V, while I/O’s operate at 5.0V (VDD).
 2010 Microchip Technology Inc.
DS41430A-page 45
PIC16F/LF720/721
NOTES:
DS41430A-page 46
 2010 Microchip Technology Inc.
PIC16F/LF720/721
6.0
I/O PORTS
6.1.1
WEAK PULL-UPS
There are as many as eighteen general purpose I/O
pins available. Depending on which peripherals are
enabled, some or all of the pins may not be available as
general purpose I/O. In general, when a peripheral is
enabled, the associated pin may not be used as a
general purpose I/O pin.
Each of the PORTA pins has an individually
configurable internal weak pull-up. Control bits
WPUA<5:0> enable or disable each pull-up (see
Register 6-5). Each weak pull-up is automatically
turned off when the port pin is configured as an output.
All pull-ups are disabled on a Power-on Reset by the
RABPU bit of the OPTION register.
6.1
6.1.2
PORTA and the TRISA Registers
PORTA is a 8-bit wide, bidirectional port. The
corresponding data direction register is TRISA
(Register 6-2). Setting a TRISA bit (= 1) will make the
corresponding PORTA pin an input (i.e., disable the
output driver). Clearing a TRISA bit (= 0) will make the
corresponding PORTA pin an output (i.e., enables
output driver and puts the contents of the output latch
on the selected pin). Example 6-1 shows how to
initialize PORTA.
Reading the PORTA register (Register 6-1) reads the
status of the pins, whereas writing to it will write to the
PORT latch. All write operations are read-modify-write
operations. Therefore, a write to a port implies that the
port pins are read, this value is modified and then
written to the PORT data latch.
The TRISA register (Register 6-2) controls the PORTA
pin output drivers, even when they are being used as
analog inputs. The user should ensure the bits in the
TRISA register are maintained set when using them as
analog inputs. I/O pins configured as analog input always
read ‘0’.
Note:
The ANSELA register must be initialized
to configure an analog channel as a digital
input. Pins configured as analog inputs
will read ‘0’.
For enable interrupt-on-change pins, the present value
is compared with the old value latched on the last read
of PORTA to determine which bits have changed or
mismatched the old value. The ‘mismatch’ outputs of
the last read are OR’d together to set the PORTA
Change Interrupt Flag bit (RABIF) in the INTCON
register. This interrupt can wake the device from Sleep.
The user, in the Interrupt Service Routine, clears the
interrupt by:
1.
2.
Any read or write of PORTA. This will end the
mismatch condition.
Clear the flag bit RABIF.
A mismatch condition will continue to set flag bit RABIF.
Reading or writing PORTA will end the mismatch
condition and allow flag bit RABIF to be cleared. The
latch holding the last read value is not affected by a
MCLR or Brown-out Reset. After these Resets, the
RABIF flag will continue to be set if a mismatch is
present.
Note:
EXAMPLE 6-1:
BANKSEL
CLRF
BANKSEL
CLRF
BANKSEL
MOVLW
MOVWF
PORTA
PORTA
ANSELA
ANSELA
TRISA
0Ch
TRISA
INITIALIZING PORTA
;
;Init PORTA
;
;digital I/O
;
;Set RA<3:2> as inputs
;and set RA<5:4,1:0>
;as outputs
 2010 Microchip Technology Inc.
INTERRUPT-ON-CHANGE
All of the PORTA pins are individually configurable as
an interrupt-on-change pin. Control bits IOCA<5:0>
enable or disable the interrupt function for each pin
(see Register 6-6). The interrupt-on-change feature is
disabled on a Power-on Reset.
When a pin change occurs at the same
time as a read operation on PORTA, the
RABIF flag will always be set. If multiple
PORTA pins are configured for the interrupt-on-change, the user may not be able
to identify which pin changed state.
DS41430A-page 47
PIC16F/LF720/721
REGISTER 6-1:
PORTA: PORTA REGISTER
U-0
U-0
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
—
—
RA5
RA4
RA3(1)
RA2
RA1
RA0
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 5-0
RA<5:0>: PORTA I/O Pin bit
1 = Port pin is > VIH
0 = Port pin is < VIL
Note 1:
x = Bit is unknown
PORTA<3> is input only.
REGISTER 6-2:
TRISA: PORTA TRI-STATE REGISTER
U-0
U-0
R/W-1
R/W-1
U-1
R/W-1
R/W-1
R/W-1
—
—
TRISA5
TRISA4
—(1)
TRISA2
TRISA1
TRISA0
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 5-0
TRISA<5:0>: PORTA Tri-State Control bit
1 = PORTA pin configured as an input (tri-stated)
0 = PORTA pin configured as an output
Note 1:
x = Bit is unknown
TRISA<3> is unimplemented and read as 1.
REGISTER 6-3:
WPUA: WEAK PULL-UP PORTA REGISTER
U-0
U-0
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
—
—
WPUA5
WPUA4
WPUA3(2)
WPUA2
WPUA1
WPUA0
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 5-0
WPUA<5:0>: Weak Pull-up PORTA Control bits
1 = Weak pull-up enabled( 1)
0 = Weak pull-up disabled
x = Bit is unknown
Note 1: Enabling weak pull-ups also requires that the RABPU bit of the OPTION register be cleared.
2: If MCLREN = 1, WPUA3 is always enabled.
DS41430A-page 48
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 6-4:
IOCA: INTERRUPT-ON-CHANGE PORTA REGISTER
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
IOCA5
IOCA4
IOCA3
IOCA2
IOCA1
IOCA0
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 5-0
IOCA<5:0>: Interrupt-on-Change PORTA Control bits
1 = Interrupt-on-change enabled(1)
0 = Interrupt-on-change disabled
x = Bit is unknown
Note 1: Interrupt-on-change also requires that the RABIE bit of the INTCON register be set.
6.1.3
ANSELA REGISTER
The ANSELA register (Register 6-5) is used to
configure the Input mode of an I/O pin to analog.
Setting the appropriate ANSELA bit high will cause all
digital reads on the pin to be read as ‘0’ and allow
analog functions on the pin to operate correctly.
The state of the ANSELA bits has no affect on digital
output functions. A pin with TRIS clear and ANSEL set
will still operate as a digital output, but the Input mode
will be analog. This can cause unexpected behavior
when executing read-modify-write instructions on the
affected port.
REGISTER 6-5:
ANSELA: PORTA ANALOG SELECT REGISTER
U-0
U-0
U-0
R/W-1
U-0
R/W-1
R/W-1
R/W-1
—
—
—
ANSA4
—
ANSA2
ANSA1
ANSA0
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
ANSA: Analog Select between Analog or Digital Function on Pin RA<4>
0 = Digital I/O. Pin is assigned to port or digital special function.
1 = Analog input. Pin is assigned as analog input(1). Digital input buffer is disabled.
bit 3
Unimplemented: Read as ‘0’
bit 2-0
ANSA<2:0>: Analog Select between Analog or Digital Function on Pins RA<2:0>, respectively
0 = Digital I/O. Pin is assigned to port or digital special function.
1 = Analog input. Pin is assigned as analog input(1). Digital input buffer is disabled.
Note 1:
Setting a pin to an analog input automatically disables the digital input circuitry. Weak pull-ups, if
available, are unaffected. The corresponding TRIS bit must be set to Input mode by the user in order to
allow external control of the voltage on the pin.
 2010 Microchip Technology Inc.
DS41430A-page 49
PIC16F/LF720/721
6.1.4
PIN DESCRIPTIONS AND
DIAGRAMS
Each PORTA pin is multiplexed with other functions. The
pins and their combined functions are briefly described
here. For specific information about individual functions
such as the A/D Converter (ADC), refer to the
appropriate section in this data sheet.
6.1.4.1
RA0/AN0/ICSPDAT
Figure 6-1 shows the diagram for this pin. This pin is
configurable to function as one of the following:
• a general purpose I/O
• an analog input for the ADC
• ICSP programming data (separate controls from
TRISA)
• ICD Debugging data (separate controls from
TRISA)
6.1.4.2
6.1.4.3
RA2/AN2/T0CKI/INT
Figure 6-3 shows the diagram for this pin. This pin is
configurable to function as one of the following:
•
•
•
•
a general purpose I/O
an analog input for the ADC
external interrupt
clock input for Timer0
The Timer0 clock input function works independently of
any TRIS register setting. Effectively, if TRISA2 = 0,
the PORTA2 register bit will output to the pad and Clock
Timer0 at the same time.
6.1.4.4
RA3/MCLR/VPP
Figure 6-4 shows the diagram for this pin. This pin is
configurable to function as one of the following:
• a general purpose I/O
• Master Clear Reset with weak pull-up
RA1/AN1/ICSPCLK
Figure 6-2 shows the diagram for this pin. This pin is
configurable to function as one of the following:
• a general purpose I/O
• an analog input for the ADC
• ICSP programming clock (separate controls from
TRISA)
• ICD Debugging clock (separate controls from
TRISA)
6.1.4.5
RA4/AN3/T1G/CLKOUT
Figure 6-5 shows the diagram for this pin. This pin is
configurable to function as one of the following:
•
•
•
•
a general purpose I/O
analog input for the ADC
Timer1 gate input
clock output
6.1.4.6
RA5/T1CKI/CLKIN
Figure 6-6 shows the diagram for this pin. This pin is
configurable to function as one of the following:
• a general purpose I/O
• Timer1 Clock input
• clock input
DS41430A-page 50
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 6-1:
BLOCK DIAGRAM OF RA0
ICSP™ mode
Analog(1)
Input mode
DEBUG
VDD
Data Bus
D
Weak
Q
CK Q
WR
WPUA
RABPU
RD
WPUA
VDD
PORT_ICDDAT
0
1
D
WR
PORTA
Q
1
0
CK Q
I/O Pin
VSS
0
1
D
WR
TRISA
TRIS_ICDDAT
Q
CK Q
RD
TRISA
Analog(1)
Input mode
RD
PORTA
D
WR
IOCA
Q
CK Q
Q
RD
IOCA
D
EN
Q
Q3
D
EN
Interrupt-on-Change
RD PORTA
ICSPDAT
To A/D Converter
Note
1:
ANSEL determines Analog Input mode.
 2010 Microchip Technology Inc.
DS41430A-page 51
PIC16F/LF720/721
FIGURE 6-2:
BLOCK DIAGRAM OF RA1
Data Bus
WR WPUA
D
Q
DEBUG
VDD
CK Q
Weak
RABPU
RD WPUA
D
WR PORTA
ICSP™ mode
Analog(1)
Input mode
Q
PORT_ICDCLK
CK Q
VDD
0
1
I/O Pin
1
0
D
Q
0
WR TRISA
CK Q
VSS
1
RD TRISA
Analog(1)
Input mode
TRIS_ICDCLK
RD PORTA
D
WR IOCA
Q
Q
CK Q
D
EN
Q3
RD IOCA
Q
D
Interrupt-on-Change
EN
RD PORTA
To A/D Converter
ICSPCLK
Note
DS41430A-page 52
1:
ANSEL determines Analog Input mode.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 6-3:
BLOCK DIAGRAM OF RA2
Data Bus
WR
WPUA
D
CK
Q
Analog(1)
Input mode
Q
Weak
To Voltage Regulator
(for PIC16F720/721 only)
RABPU
RD
WPUA
D
WR
PORTA
VDD
CK
VDD
Q
Q
I/O Pin
D
WR
TRISA
CK
Q
Q
VSS
Analog(1)
Input mode
RD
TRISA
RD
PORTA
D
WR
IOCA
CK
Q
Q
D
Q
EN
RD
IOCA
Q
Interrupt-onChange
Q3
D
EN
RD PORTA
To Timer0
To INT
To A/D Converter
Note
1:
ANSEL determines Analog Input mode.
 2010 Microchip Technology Inc.
DS41430A-page 53
PIC16F/LF720/721
FIGURE 6-4:
BLOCK DIAGRAM OF RA3
FIGURE 6-5:
BLOCK DIAGRAM OF RA4
VDD
MCLRE
Analog(2)
Input mode
Weak
Data Bus
Data Bus
Reset
RD
TRISA
Input
Pin
WR
WPUA
D
CK
Q
VDD
Q
Weak
VSS
MCLRE
RD
PORTA
D
WR
IOCA
MCLRE
CLK
modes
CK
VSS
RABPU
RD
WPUA
Q
Q
VDD
CLKOUT
Enable
D
Q
EN
RD
IOCA
Interrupt-onChange
Q
D
Q3
D
WR
PORTA
CK
FOSC/4
Q
0
I/O Pin
Q
CLKOUT
Enable
EN
VSS
D
RD PORTA
1
WR
TRISA
CK
Q
INTOSC/
RC/EC(1)
Q
CLKOUT
Enable
RD
TRISA
Analog
Input mode
RD
PORTA
D
WR
IOCA
CK
Q
Q
D
Q
EN
RD
IOCA
Q
Q3
D
EN
Interrupt-onChange
RD PORTA
To T1G
To A/D Converter
Note
DS41430A-page 54
1:
With CLKOUT option.
2:
ANSEL determines Analog Input mode.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 6-6:
BLOCK DIAGRAM OF RA5
INTOSC
mode
Data Bus
WR
WPUA
D
CK
VDD
Q
Weak
Q
RABPU
RD
WPUA
D
WR
PORTA
CK
VDD
Q
Q
I/O Pin
D
WR
TRISA
CK
Q
Q
VSS
INTOSC
mode
RD
TRISA
RD
PORTA
D
WR
IOCA
CK
Q
Q
D
Q
EN
Q3
RD
IOCA
Q
D
EN
Interrupt-onChange
RD PORTA
To TMR1 or CLKIN
TABLE 6-1:
Name
SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Bit 7
Bit 6
Bit 5
ADCON0
—
—
ANSELA
—
—
RABPU
—
OPTION_REG
PORTA
TRISA
Legend:
—
Bit 4
Bit 3
CHS3
CHS2
—
ANSA4
INTEDG
T0CS
T0SE
PSA
PS2
—
RA5
RA4
RA3
RA2
—
TRISA5
TRISA4
—
TRISA2
TRISA1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
Bit 2
Bit 1
CHS1
CHS0
GO/DONE
ADON
--00 0000
--00 0000
—
ANSA2
ANSA1
ANSA0
---1 -111
---1 -111
PS1
PS0
1111 1111
1111 1111
RA1
RA0
--xx xxxx
--xx xxxx
TRISA0
--11 -111
--11 -111
x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTA.
 2010 Microchip Technology Inc.
DS41430A-page 55
PIC16F/LF720/721
6.2
PORTB and TRISB Registers
PORTB is an 8-bit wide, bidirectional port. The
corresponding data direction register is TRISB
(Register 6-7). 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., enable the output driver and
put the contents of the output latch on the selected pin).
Example 6-2 shows how to initialize PORTB.
Reading the PORTB register (Register 6-6) reads the
status of the pins, whereas writing to it will write to the
PORT latch. All write operations are read-modify-write
operations. Therefore, a write to a port implies that the
port pins are read, this value is modified and then written
to the PORT data latch.
The TRISB register (Register 6-7) controls the PORTB
pin output drivers, even when they are being used as
analog inputs. The user should ensure the bits in the
TRISB register are maintained set when using them as
analog inputs. I/O pins configured as analog input always
read ‘0’. Example 6-2 shows how to initialize PORTB.
EXAMPLE 6-2:
BANKSEL
CLRF
BANKSEL
CLRF
BANKSEL
MOVLW
MOVWF
Note:
INITIALIZING PORTB
PORTB
;
PORTB
;Init PORTB
ANSELB
ANSELB ;Make RB<7:4> digital
TRISB
;
B’11110000’;Set RB<7:4> as inputs
TRISB
;
The ANSELB register must be initialized
to configure an analog channel as a digital
input. Pins configured as analog inputs
will read ‘0’.
6.2.1
ANSELB REGISTER
The ANSELB register (Register 6-10) is used to
configure the Input mode of an I/O pin to analog.
Setting the appropriate ANSELB bit high will cause all
digital reads on the pin to be read as ‘0’ and allow
analog functions on the pin to operate correctly.
The state of the ANSELB bits has no affect on digital
output functions. A pin with TRIS clear and ANSELB
set will still operate as a digital output, but the Input
mode will be analog. This can cause unexpected
behavior
when
executing
read-modify-write
instructions on the affected port.
6.2.2
WEAK PULL-UPS
Each of the PORTB pins has an individually configurable
internal weak pull-up. Control bits WPUB<7:4> enable or
disable each pull-up (see Register 6-8). Each weak pullup is automatically turned off when the port pin is
configured as an output. All pull-ups are disabled on a
Power-on Reset by the RABPU bit of the OPTION
register.
6.2.3
INTERRUPT-ON-CHANGE
All of the PORTB pins are individually configurable as an
interrupt-on-change pin. Control bits IOCB<7:4> enable
or disable the interrupt function for each pin. Refer to
Register 6-9. The interrupt-on-change feature is
disabled on a Power-on Reset.
For enabled interrupt-on-change pins, the present value
is compared with the old value latched on the last read
of PORTB to determine which bits have changed or
mismatched the old value. The ‘mismatch’ outputs of
the last read are OR’d together to set the PORTB
Change Interrupt Flag bit (RABIF) in the INTCON
register.
This interrupt can wake the device from Sleep. The user,
in the Interrupt Service Routine, clears the interrupt by:
a)
b)
Any read or write of PORTB. This will end the
mismatch condition.
Clear the flag bit RABIF.
A mismatch condition will continue to set flag bit RABIF.
Reading or writing PORTB will end the mismatch
condition and allow flag bit RABIF to be cleared. The latch
holding the last read value is not affected by a MCLR nor
Brown-out Reset. After these Resets, the RABIF flag will
continue to be set if a mismatch is present.
Note:
DS41430A-page 56
When a pin change occurs at the same
time as a read operation on PORTB, the
RABIF flag will always be set. If multiple
PORTB pins are configured for the
interrupt-on-change, the user may not be
able to identify which pin changed state.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 6-6:
PORTB: PORTB REGISTER
R/W-x
R/W-x
R/W-x
R/W-x
U-0
U-0
U-0
U-0
RB7
RB6
RB5
RB4
—
—
—
—
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 7-4
RB<7:4>: PORTB I/O Pin bit
1 = Port pin is > VIH
0 = Port pin is < VIL
bit 3-0
Unimplemented: Read as ‘0’
REGISTER 6-7:
x = Bit is unknown
TRISB: PORTB TRI-STATE REGISTER
R/W-1
R/W-1
R/W-1
R/W-1
U-0
U-0
U-0
U-0
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
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 7-4
TRISB<7:4>: PORTB Tri-State Control bit
1 = PORTB pin configured as an input (tri-stated)
0 = PORTB pin configured as an output
bit 3-0
Unimplemented: Read as ‘0’
REGISTER 6-8:
x = Bit is unknown
WPUB: WEAK PULL-UP PORTB REGISTER
R/W-1
R/W-1
R/W-1
R/W-1
U-0
U-0
U-0
U-0
WPUB7
WPUB6
WPUB5
WPUB4
—
—
—
—
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 7-4
WPUB<7:4>: Weak Pull-up PORTB Control bits
1 = Weak pull-up enabled (1,2)
0 = Weak pull-up disabled
bit 3-0
Unimplemented: Read as ‘0’
Note 1:
2:
x = Bit is unknown
Global RABPU bit of the OPTION register must be cleared for individual pull-ups to be enabled.
The weak pull-up device is automatically disabled if the pin is in configured as an output.
 2010 Microchip Technology Inc.
DS41430A-page 57
PIC16F/LF720/721
REGISTER 6-9:
R/W-0
IOCB: INTERRUPT-ON-CHANGE PORTB REGISTER
R/W-0
IOCB7
IOCB6
R/W-0
IOCB5
R/W-0
U-0
U-0
U-0
U-0
IOCB4
—
—
—
—
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 7-4
IOCB<7:4>: Interrupt-on-Change PORTB Control bits
1 = Interrupt-on-change enabled(1)
0 = Interrupt-on-change disabled
bit 3-0
Unimplemented: Read as ‘0’
x = Bit is unknown
Note 1: Interrupt-on-change also requires that the RABIE bit of the INTCON register be set.
REGISTER 6-10:
ANSELB: PORTB ANALOG SELECT REGISTER
U-0
U-0
R/W-1
R/W-1
U-0
U-0
U-0
U-0
—
—
ANSB5
ANSB4
—
—
—
—
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
ANSB<5:4>: Analog Select between Analog or Digital Function on Pins RB<5:4>, respectively
0 = Digital I/O. Pin is assigned to port or digital special function.
1 = Analog input. Pin is assigned as analog input(1). Digital input buffer disabled.
bit 3-0
Unimplemented: Read as ‘0’
Note 1:
Setting a pin to an analog input automatically disables the digital input circuitry. Weak pull-ups, if
available, are unaffected. The corresponding TRIS bit must be set to Input mode by the user, in order to
allow external control of the voltage on the pin.
DS41430A-page 58
 2010 Microchip Technology Inc.
PIC16F/LF720/721
6.2.4
PIN DESCRIPTIONS AND
DIAGRAMS
Each PORTB pin is multiplexed with other functions. The
pins and their combined functions are briefly described
here. For specific information about individual functions
such as the SSP, I2C™ or interrupts, refer to the
appropriate section in this data sheet.
6.2.4.1
RB4/AN10/SDI/SDA
Figure 6-7 shows the diagram for this pin. The RB4 pin
is configurable to function as one of the following:
FIGURE 6-7:
Data Bus
WR
WPUB
WR
PORTB
6.2.4.2
WR
TRISB
Figure 6-8 shows the diagram for this pin. The RB5 pin
is configurable to function as one of the following:
• General purpose I/O. Individually controlled
interrupt-on-change. Individually enabled pull-up.
• Analog input for the A/D
• USART asynchronous receive
• USART synchronous receive
6.2.4.3
RB6/SCK/SCL
Figure 6-9 shows the diagram for this pin. The RB6 pin
is configurable to function as one of the following:
• General purpose I/O. Individually controlled
interrupt-on-change. Individually enabled pull-up.
• Synchronous Serial Port clock for both SPI and
I2C
6.2.4.4
VDD
CK Q
Weak
RABPU
D
Q
SSPEN
VDD
SSP
0
1
CK Q
1
0
D
Q
CK
I/O Pin
From 1
0
SSP
VSS
Q
1
0
Analog(1)
Input mode
RD
TRISB
RD
PORTB
D
Q
Q
CK Q
WR
IOCB
D
EN
RD
IOCB
Q
Q3
D
ST
EN
Interrupt-onChange
RD PORTB
To SSP
To A/D Converter
RB7/TX/CK
Figure 6-10 shows the diagram for this pin. The RB7
pin is configurable to function as one of the following:
Q
Analog(1)
Input mode
RD
WPUB
• General purpose I/O. Individually controlled
interrupt-on-change. Individually enabled pull-up.
• Analog input for the A/D
• Synchronous Serial Port Input (SPI)
• I2C data I/O
RB5/AN11/RX/DT
D
BLOCK DIAGRAM OF RB4
Note
1:
ANSEL determines Analog Input mode.
• General purpose I/O. Individually controlled
interrupt-on-change. Individually enabled pull-up.
• USART asynchronous transmit
• USART synchronous clock
 2010 Microchip Technology Inc.
DS41430A-page 59
PIC16F/LF720/721
FIGURE 6-8:
Data Bus
WR
WPUB
D
BLOCK DIAGRAM OF RB5
Q
Analog(1)
Input mode
Data Bus
VDD
CK Q
WR
WPUB
Weak
D
BLOCK DIAGRAM OF RB6
Q
VDD
CK Q
Weak
RABPU
RD
WPUB
RABPU
RD
WPUB
FIGURE 6-9:
SYNC
SPEN
D
D
WR
PORTB
Q
CK Q
VDD
AUSART
DT 1
0
WR
PORTB
1
0
D
WR
TRISB
Q
CK Q
WR
TRISB
Q
VDD
1
0
From
SSP 1
0
I/O Pin
VSS
1
0
RD
TRISB
Analog(1)
Input mode
RD
PORTB
RD
PORTB
D
D
WR
IOCB
CK
Q
SSPEN
SSP
Clock 1
0
VSS
0
1
RD
TRISB
CK Q
D
I/O Pin
From
AUSART 1
0
Q
Q
Q
CK Q
D
EN
RD
IOCB
WR
IOCB
Q
Q
CK Q
D
EN
Q3
RD
IOCB
Q
Q3
D
ST
Q
D
ST
EN
EN
Interrupt-onChange
Interrupt-onChange
RD PORTB
RD PORTB
To SSP
To AUSART RX/DT
To A/D Converter
Note
1:
ANSEL determines Analog Input mode.
DS41430A-page 60
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 6-10:
Data Bus
WR
WPUB
D
BLOCK DIAGRAM OF RB7
Q
VDD
CK Q
Weak
RABPU
RD
WPUB
SPEN
TXEN
SYNC
D
WR
PORTB
AUSART
CK 0
1
AUSART
TX
1
0
Q
CK Q
VDD
0
1
0
1
D
WR
TRISB
I/O Pin
Q
‘1’
CK Q
0
1
VSS
1
0
RD
TRISB
RD
PORTB
D
WR
IOCB
Q
Q
CK Q
D
Q3
EN
RD
IOCB
Q
D
EN
Interrupt-onChange
RD PORTB
TABLE 6-2:
Name
SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on all
other
Resets
ADCON0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
--00 0000
--00 0000
ANSELB
—
—
ANSB5
ANSB4
—
—
—
—
--11 ----
--11 ----
INTCON
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
IOCB
IOCB7
IOCB6
IOCB5
IOCB4
—
—
—
—
0000 ----
0000 ----
OPTION_REG
RABPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
1111 1111
1111 1111
RB7
RB6
RB5
RB4
—
—
—
—
xxxx ----
uuuu ----
TMR1GE
T1GPOL
T1GTM
T1GSPM
T1GGO/
DONE
T1GVAL
T1GSS1
T1GSS0
0000 0x00
uuuu uxuu
PORTB
T1GCON
TRISB
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
1111 ----
WPUB
WPUB7
WPUB6
WPUB5
WPUB4
—
—
—
—
1111 ----
1111 ----
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
TXREG
AUSART Transmit Data Register
0000 0000
0000 0000
RCREG
AUSART Receive Data Register
0000 0000
0000 0000
Legend:
x = unknown, u = unchanged, - = unimplemented locations read as ‘0’. Shaded cells are not used by PORTB.
 2010 Microchip Technology Inc.
DS41430A-page 61
PIC16F/LF720/721
6.3
PORTC and TRISC Registers
PORTC is a 8-bit wide, bidirectional port. The
corresponding data direction register is TRISC
(Register 6-12). 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., enable the output driver and
put the contents of the output latch on the selected pin).
Example 6-3 shows how to initialize PORTC.
Reading the PORTC register (Register 6-11) reads the
status of the pins, whereas writing to it will write to the
PORT latch. All write operations are read-modify-write
operations. Therefore, a write to a port implies that the
port pins are read, this value is modified and then written
to the PORT data latch.
The TRISC register (Register 6-12) controls the PORTC
pin output drivers, even when they are being used as
analog inputs. The user should ensure the bits in the
TRISC register are maintained set when using them as
analog inputs. I/O pins configured as analog input always
read ‘0’.
EXAMPLE 6-3:
BANKSEL
CLRF
BANKSEL
MOVLW
MOVWF
6.3.1
INITIALIZING PORTC
PORTC
PORTC
TRISC
B‘00001100’
TRISC
;
;Init PORTC
;
;Set RC<3:2> as inputs
;and set RC<7:4,1:0>
;as outputs
ANSELC REGISTER
The ANSELC register (Register 6-13) is used to
configure the Input mode of an I/O pin to analog.
Setting the appropriate ANSELC bit high will cause all
digital reads on the pin to be read as ‘0’ and allow
analog functions on the pin to operate correctly.
The state of the ANSELC bits has no effect on digital
output functions. A pin with TRIS clear and ANSELC
set will still operate as a digital output, but the Input
mode will be analog. This can cause unexpected
behavior
when
executing
read-modify-write
instructions on the affected port.
REGISTER 6-11:
PORTC: PORTC REGISTER
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
x = Bit is unknown
RC<7:0>: PORTC General Purpose I/O Pin bits
1 = Port pin is > VIH
0 = Port pin is < VIL
DS41430A-page 62
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 6-12:
TRISC: PORTC TRI-STATE 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
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
x = Bit is unknown
TRISC<7:0>: PORTC Tri-State Control bits
1 = PORTC pin configured as an input (tri-stated)
0 = PORTC pin configured as an output
REGISTER 6-13:
ANSELC: ANALOG SELECT REGISTER FOR PORTC
R/W-1
R/W-1
U-0
U-0
R/W-1
R/W-1
R/W-1
R/W-1
ANSC7
ANSC6
—
—
ANSC3
ANSC2
ANSC1
ANSC0
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
ANSC<7:6>: Analog Select between Analog or Digital Function on Pins RB<7:6>, respectively
0 = Digital I/O. Pin is assigned to port or digital special function.
1 = Analog input. Pin is assigned as analog input(1). Digital input buffer disabled.
bit 5-4
Unimplemented: Read as ‘0’
bit 3-0
ANSC<3:0>: Analog Select between Analog or Digital Function on Pins RC<3:0>, respectively
0 = Digital I/O. Pin is assigned to port or digital special function.
1 = Analog input. Pin is assigned as analog input(1). Digital input buffer disabled.
Note 1: Setting a pin to an analog input automatically disables the digital input circuitry. Weak pull-ups, if available,
are unaffected. The corresponding TRIS bit must be set to Input mode by the user in order to allow external
control of the voltage on the pin.
 2010 Microchip Technology Inc.
DS41430A-page 63
PIC16F/LF720/721
6.3.2
RC0/AN4
Figure 6-11 shows the diagram for this pin. The RC0 pin
is configurable to function as one of the following:
FIGURE 6-11:
Data Bus
• general purpose I/O
• analog input for the A/D
6.3.3
RC1/AN5
D
WR
PORTC
Figure 6-11 shows the diagram for this pin. The RC1 pin
is configurable to function as one of the following:
• general purpose I/O
• analog input for the A/D
6.3.4
RC2/AN6
Figure 6-12 shows the diagram for this pin. The RC2
pin is configurable to function as one of the following:
• general purpose I/O
• analog input for the A/D
BLOCK DIAGRAM OF RC0
AND RC1
VDD
Q
CK
Q
I/O Pin
D
WR
TRISC
Q
CK
Q
VSS
Analog Input
mode(1)
RD
TRISC
RD
PORTC
To A/D Converter
6.3.5
RC3/AN7
Figure 6-12 shows the diagram for this pin. The RC3 pin
is configurable to function as one of the following:
Note
1:
ANSEL determines Analog Input mode.
• general purpose I/O
• analog input for the A/D
FIGURE 6-12:
6.3.6
RC4
Figure 6-13 shows the diagram for this pin. The RC4 pin
functions as one of the following:
Data Bus
• general purpose I/O
6.3.7
RC5/CCP1
Figure 6-14 shows the diagram for this pin. The RC5 pin
is configurable to function as one of the following:
• general purpose I/O
• Capture, Compare or PWM (1 output)
6.3.8
RC6/AN8/SS
Figure 6-15 shows the diagram for this pin. The RC6 pin
is configurable to function as one of the following:
• general purpose I/O
• analog input for the A/D
• SS input to SSP
6.3.9
BLOCK DIAGRAM OF RC2
AND RC3
D
WR
PORTC
CK
VDD
Q
Q
I/O Pin
D
WR
TRISC
CK
Q
Q
VSS
Analog Input
mode(1)
RD
TRISC
RD
PORTC
To A/D Converter
RC7/AN9/SDO
Figure 6-16 shows the diagram for this pin. The RC7 pin
is configurable to function as one of the following:
Note
1:
ANSEL determines Analog Input mode.
• general purpose I/O
• analog input for the A/D
• SDO output of SSP
DS41430A-page 64
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 6-13:
BLOCK DIAGRAM OF RC4
FIGURE 6-15:
Data Bus
VDD
D
I/O Pin
Data Bus
D
WR
PORTC
WR
TRISC
WR
PORTC
CK
VDD
Q
Q
Q
CK Q
D
BLOCK DIAGRAM OF RC6
I/O Pin
VSS
D
WR
TRISC
Q
CK Q
CK
Q
Q
VSS
Analog Input
mode(1)
RD
TRISC
RD
TRISC
RD
PORTC
To SS Input
RD
PORTC
To A/D Converter
Note
FIGURE 6-14:
1:
ANSEL determines Analog Input mode.
BLOCK DIAGRAM OF RC5
Data bus
CCP1OUT
Enable
D
WR
PORTC
CK
FIGURE 6-16:
Q
Q
CCP1OUT
PORT/SDO
Select
0
1
Data Bus
SDO
1
0
D
WR
TRISC
BLOCK DIAGRAM OF RC7
VDD
CK
Q
Q
0
1
I/O Pin
D
VSS
WR
PORTC
RD
TRISC
CK
Q
1
0
VDD
Q
I/O Pin
D
RD
PORTC
WR
TRISC
To CCP1 input
RD
TRISC
CK
Q
Q
VSS
Analog Input
mode(1)
RD
PORTC
To A/D Converter
Note
 2010 Microchip Technology Inc.
1:
ANSEL determines Analog Input mode.
DS41430A-page 65
PIC16F/LF720/721
TABLE 6-3:
SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR,
BOR
Value on all
other
Resets
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
PORTC
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
xxxx xxxx
uuuu uuuu
ANSELC
ANSC7
ANSC6
—
—
ANSC3
ANSC2
ANSC1
ANSC0
11-- 1111
11-- 1111
Name
ADCON0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
--00 0000
--00 0000
SSPCON
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
0000 0000
0000 0000
—
—
DC1
B1
CCP1M3
CCP1M2
CCP1M1
CCP1M0
--00 0000
--00 0000
CCP1CON
Legend:
x = unknown, u = unchanged, - = unimplemented locations read as ‘0’. Shaded cells are not used by PORTC.
DS41430A-page 66
 2010 Microchip Technology Inc.
PIC16F/LF720/721
7.0
OSCILLATOR MODULE
7.1
Overview
Clock source modes are configured by the FOSC bits
in Configuration Word 1 (CONFIG1). The oscillator
module can be configured for one of eight modes of
operation.
The oscillator module has a wide variety of clock sources
and selection features that allow it to be used in a wide
range of applications while maximizing performance and
minimizing power consumption. Figure 7-1 illustrates a
block diagram of the oscillator module.
1.
2.
3.
Clock sources can be configured from external
oscillators, quartz crystal resonators, ceramic resonators
and Resistor-Capacitor (RC) circuits. In addition, the
system can be configured to use an internal calibrated
high-frequency oscillator as clock source, with a choice
of selectable speeds via software.
FIGURE 7-1:
EC – CLKOUT function on RA4/CLKOUT pin,
CLKIN on RA5/CLKIN.
EC – I/O function on RA4/CLKOUT pin, CLKIN
on RA5/CLKIN.
INTOSC – CLKOUT function on RA4/CLKOUT
pin, I/O function on RA5/CLKIN
INTOSCIO – I/O function on RA4/CLKOUT pin,
I/O function on RA5/CLKIN
4.
SIMPLIFIED PIC® MCU CLOCK SOURCE BLOCK DIAGRAM
FOSC<2:0>
(Configuration Word 1)
EC
MUX
CLKIN
Internal Oscillator
IRCF<1:0>
(OSCCON Register)
MFINTOSC
500 kHz
INTOSC
16 MHz/500 kHz
1
Postscaler
HFINTOSC
8 MHz/250 kHz
4 MHz/125 kHz
2 MHz/62.5 kHz
11
10
MUX
MUX
0
32x
PLL
System Clock
(CPU and Peripherals)
01
00
PLLEN
(Configuration Word 1)
 2010 Microchip Technology Inc.
DS41430A-page 67
PIC16F/LF720/721
7.2
Clock Source Modes
Clock source modes can be classified as external or
internal.
• Internal clock source (INTOSC) is contained
within the oscillator module and derived from a
500 kHz high precision oscillator. The oscillator
module has eight selectable output frequencies,
with a maximum internal frequency of 16 MHz.
• The external clock mode (EC) relies on an
external signal for the clock source.
The system clock can be selected between external or
internal clock sources via the FOSC bits of the
Configuration Word 1.
7.3
Internal Clock Modes
The oscillator module has eight output frequencies
derived from a 500 kHz high precision oscillator. The
IRCF bits of the OSCCON register select the
postscaler applied to the clock source dividing the
frequency by 1, 2, 4 or 8. Setting the PLLEN bit of the
Configuration Word 1 locks the internal clock source to
16 MHz before the postscaler is selected by the IRCF
bits. The PLLEN bit must be set or cleared at the time
of programming; therefore, only the upper or low four
clock source frequencies are selectable in software.
Internal clock sources are contained internally within
the oscillator module. The internal oscillator block has
two internal oscillators and a dedicated Phase Locked
Loop that are used to generate three internal system
clock sources: the 16 MHz High-Frequency Internal
Oscillator (HFINTOSC) and the 500 kHz (MFINTOSC).
Both can be user-adjusted via software using the
OSCTUNE register (Register 7-2).
7.3.1
INTOSC AND INTOSCIO MODES
7.3.2
FREQUENCY SELECT BITS (IRCF)
The output of the 500 kHz MFINTOSC and 16 MHz
HFINTOSC, with Phase Locked Loop enabled, connect
to a postscaler and multiplexer (see Figure 7-1). The
Internal Oscillator Frequency Select bits (IRCF) of the
OSCCON register select the frequency output of the
internal oscillator. Depending upon the PLLEN bit, one
of four frequencies of two frequency sets can be
selected via software:
If PLLEN = 1, HFINTOSC frequency selection is as
follows:
•
•
•
•
16 MHz
8 MHz (default after Reset)
4 MHz
2 MHz
If PLLEN = 0, MFINTOSC frequency selection is as
follows:
•
•
•
•
500 kHz
250 kHz (default after Reset)
125 kHz
62.5 kHz
Note:
Following any Reset, the IRCF<1:0> bits
of the OSCCON register are set to ‘10’ and
the frequency selection is set to 8 MHz or
250 kHz. The user can modify the IRCF
bits to select a different frequency.
There is no start-up delay before a new frequency
selected in the IRCF bits takes effect. This is because
the old and new frequencies are derived from INTOSC
via the postscaler and multiplexer.
Start-up delay specifications are located in the
Table 23-2
in
Section 23.0
“Electrical
Specifications”.
The INTOSC and INTOSCIO modes configure the
internal oscillators as the system clock source when
the device is programmed using the oscillator selection
or the FOSC<2:0> bits in the CONFIG1 register. See
Section 8.0 “Device Configuration” for more
information.
In INTOSC mode, CLKIN is available for general
purpose I/O. CLKOUT outputs the selected internal
oscillator frequency divided by 4. The CLKOUT signal
may be used to provide a clock for external circuitry,
synchronization, calibration, test or other application
requirements.
In INTOSCIO mode, CLKIN and CLKOUT are available
for general purpose I/O.
DS41430A-page 68
 2010 Microchip Technology Inc.
PIC16F/LF720/721
7.4
Oscillator Control
The Oscillator Control (OSCCON) register (Figure 7-1)
displays the status and allows frequency selection of the
internal oscillator (INTOSC) system clock. The
OSCCON register contains the following bits:
• Frequency selection bits (IRCF)
• Status Locked bits (ICSL)
• Status Stable bits (ICSS)
REGISTER 7-1:
OSCCON: OSCILLATOR CONTROL REGISTER
U-0
U-0
R/W-1
R/W-0
R-q
R-q
U-0
U-0
—
—
IRCF1
IRCF0
ICSL
ICSS
—
—
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
q = Value depends on condition
bit 7-6
Unimplemented: Read as ‘0’
bit 5-4
IRCF<1:0>: Internal Oscillator Frequency Select bits
When PLLEN = 1 (16 MHz HFINTOSC)
11 = 16 MHz
10 = 8 MHz (POR value)
01 = 4 MHz
00 = 2 MHz
When PLLEN = 0 (500 kHz MFINTOSC)
11 = 500 kHz
10 = 250 kHz (POR value)
01 = 125 kHz
00 = 62.5 kHz
bit 3
ICSL: Internal Clock Oscillator Status Locked bit (2% Stable)
1 = 16 MHz/500 kHz internal oscillator is in lock
0 = 16 MHz/500 kHz internal oscillator has not yet locked
bit 2
ICSS: Internal Clock Oscillator Status Stable bit (0.5% Stable)
1 = 16 MHz/500 kHz internal oscillator has stabilized to its maximum accuracy
0 = 16 MHz/500 kHz internal oscillator has not yet reached its maximum accuracy
bit 1-0
Unimplemented: Read as ‘0’
 2010 Microchip Technology Inc.
DS41430A-page 69
PIC16F/LF720/721
7.5
Oscillator Tuning
The INTOSC is factory calibrated but can be adjusted
in software by writing to the OSCTUNE register
(Register 7-2).
The default value of the OSCTUNE register is ‘0’. The
value is a 6-bit two’s complement number.
When the OSCTUNE register is modified, the INTOSC
frequency will begin shifting to the new frequency. Code
execution continues during this shift. There is no
indication that the shift has occurred.
REGISTER 7-2:
OSCTUNE: OSCILLATOR TUNING REGISTER
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
TUN5
TUN4
TUN3
TUN2
TUN1
TUN0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
Unimplemented: Read as ‘0’
bit 5-0
TUN<5:0>: Frequency Tuning bits
01 1111 = Maximum frequency
01 1110 =
•
•
•
00 0001 =
00 0000 = Oscillator module is running at the factory-calibrated frequency.
11 1111 =
•
•
•
10 0000 = Minimum frequency
DS41430A-page 70
 2010 Microchip Technology Inc.
PIC16F/LF720/721
7.6
External Clock Modes
7.6.1
EC MODE
The External Clock (EC) mode allows an externally
generated logic level as the system clock source. When
operating in this mode, an external clock source is
connected to the CLKOUT input and the CLKIN is
available for general purpose I/O. Figure 7-2 shows the
pin connections for EC mode.
FIGURE 7-2:
EXTERNAL CLOCK (EC)
MODE OPERATION
CLKIN
Clock from
Ext. System
PIC® MCU
I/O
TABLE 7-1:
CLKOUT
SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
CONFIG1(1)
—
CP
MCLRE
PWRTE
OSCCON
—
—
IRCF1
IRCF0
—
—
TUN5
TUN4
OSCTUNE
Legend:
Note 1:
Value on
POR, BOR
Value on
all other
Resets(1)
Bit 2
Bit 1
Bit 0
WDTEN
—
FOSC1
FOSC0
—
—
ICSL
ICSS
—
—
--10 qq--
--10 qq--
TUN3
TUN2
TUN1
TUN0
--00 0000
--uu uuuu
x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by oscillators.
See Configuration Word 1 (Register 8-1) for operation of all bits.
 2010 Microchip Technology Inc.
DS41430A-page 71
PIC16F/LF720/721
NOTES:
DS41430A-page 72
 2010 Microchip Technology Inc.
PIC16F/LF720/721
8.0
DEVICE CONFIGURATION
Device configuration consists of Configuration Word 1
and Configuration Word 2 registers, code protection
and device ID.
8.1
Configuration Words
There are several Configuration Word bits that allow
different oscillator and memory protection options.
These are implemented as Configuration Word 1
register at 2007h and Configuration Word 2 register at
2008h. These registers are only accessible during
programming.
 2010 Microchip Technology Inc.
DS41430A-page 73
PIC16F/LF720/721
REGISTER 8-1:
CONFIGURATION WORD 1
R/P-1
—
—
DEBUG
(1)
R/P-1
U-1
U-1
R/P-1
R/P-1
PLLEN
—
—
BOREN1
BOREN0
bit 15
bit 8
U-1
R/P-1
R/P-1
R/P-1
R/P-1
U-1
R/P-1
R/P-1
—
CP
MCLRE
PWRTE
WDTEN
—
FOSC1
FOSC0
bit 7
bit 0
Legend:
P = Programmable 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
x = Bit is unknown
bit 13
DEBUG(1): Debugger Mode bit
0 = Background debugger is enabled
1 = Background debugger is disabled
bit 12
PLLEN: INTOSC PLL Enable bit
0 = INTOSC frequency is 500 kHz
1 = INTOSC frequency is 16 MHz (32x)
bit 11-10
Unimplemented: Read as ‘1’
bit 9-8
BOREN<1:0>: Brown-out Reset Enable bits (2)
0x = Brown-out Reset disabled
10 = Brown-out Reset enabled during operation and disabled in Sleep
11 = Brown-out Reset enabled
bit 7
Unimplemented: Read as ‘1’
bit 6
CP: Flash Program Memory Code Protection bit
PIC16F720/721
0 = 0000h to 07FFh/0FFFh code protection on
1 = Code protection off
bit 5
MCLRE: RA3/MCLR/VPP Pin Function Select bit
1 = RA3/MCLR/VPP pin function is MCLR; Weak pull-up enabled.
0 = RA3/MCLR/VPP pin function is digital input; MCLR internally disabled; Weak pull-up disabled
bit 4
PWRTE: Power-up Timer Enable bit
0 = PWRT enabled
1 = PWRT disabled
bit 3
WDTEN: Watchdog Timer Enable bit
0 = WDT disabled
1 = WDT enabled
bit 2
Unimplemented: Read as ‘1’
bit 1-0
FOSC<1:0>: Oscillator Selection bits
11 = EC oscillator: CLKOUT function on RA4/CLKOUT pin, CLKIN on RA5/CLKIN
10 = EC oscillator: I/O function on RA4/CLKOUT pin, CLKIN on RA5/CLKIN
01 = INTOSC oscillator: CLKOUT function on RA4/CLKOUT pin, I/O function on RA5/CLKIN
00 = INTOSCIO oscillator: I/O function on RA4/CLKOUT pin, I/O function on RA5/CLKIN
Note 1: The Configuration bit is managed automatically by the device development tools. The user should not attempt to manually write this bit location. However, the user should ensure that this location has been programmed to a ‘1’ and the device
checksum is correct for proper operation of production software.
2: Fixed Voltage Reference is automatically enabled whenever the BOR is enabled.
DS41430A-page 74
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 8-2:
—
CONFIGURATION WORD 2
—
U-1
U-1
U-1
U-1
U-1
U-1
—
—
—
—
—
—
bit 15
bit 8
U-1
U-1
U-1
Reserved
U-1
U-1
R/P-1
R/P-1
—
—
—
—
—
—
WRT1
WRT0
bit 7
bit 0
Legend:
P = Programmable 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 13-5
Unimplemented: Read as ‘1’
bit 4
Reserved: Maintain as ‘1’
bit 3-2
Unimplemented: Read as ‘1’
bit 1-0
WRT<1:0>: Flash Memory Self-Write Protection bits
x = Bit is unknown
2 kW Flash memory: PIC16F722/LF722:
11 = Write protection off
10 = 000h to 1FFh write-protected, 200h to 7FFh may be modified by EECON control
01 = 000h to 3FFh write-protected, 400h to 7FFh may be modified by EECON control
00 = 000h to 7FFh write-protected, no addresses may be modified by EECON control
4 kW Flash memory: PIC16F723/LF723:
11 = Write protection off
10 = 000h to 1FFh write-protected, 200h to FFFh may be modified by EECON control
01 = 000h to 7FFh write-protected, 800h to FFFh may be modified by EECON control
00 = 000h to FFFh write-protected, no addresses may be modified by EECON control
 2010 Microchip Technology Inc.
DS41430A-page 75
PIC16F/LF720/721
8.2
Code Protection
If the code protection bit(s) have not been
programmed, the on-chip program memory can be
read out using ICSP™ for verification purposes.
Note:
8.3
The entire Flash program memory will be
erased when the code protection is turned
off. See the “PIC16F72X/PIC16LF72X
Memory Programming Specification”
(DS41332) for more information.
User ID
Four memory locations (2000h-2003h) are designated
as ID locations where the user can store checksum or
other code identification numbers. These locations are
not accessible during normal execution, but are readable and writable during Program/Verify mode. Only
the Least Significant 7 bits of the ID locations are
reported when using MPLAB® IDE. See the
“PIC16F72X/PIC16LF72X Memory Programming
Specification” (DS41332) for more information.
DS41430A-page 76
 2010 Microchip Technology Inc.
PIC16F/LF720/721
9.0
ANALOG-TO-DIGITAL
CONVERTER (ADC) MODULE
The Analog-to-Digital Converter (ADC) allows
conversion of an analog input signal to a 8-bit binary
representation of that signal. This device uses analog
inputs, which are multiplexed into a single sample and
hold circuit. The output of the sample and hold is
connected to the input of the converter. The converter
generates a 8-bit binary result via successive
approximation and stores the conversion result into the
ADC result register (ADRES). Figure 9-1 shows the
block diagram of the ADC.
The ADC voltage reference is software selectable to be
either internally generated or externally supplied.
The ADC can generate an interrupt upon completion of
a conversion. This interrupt can be used to wake-up the
device from Sleep.
FIGURE 9-1:
ADC BLOCK DIAGRAM
AVDD
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
AN8
AN9
AN10
0000
0001
0010
0011
0100
0101
AN11
1011
Temperature Indicator
FVREF
1110
1111
0110
0111
1000
1001 GO/DONE
1010
ADC
8
ADRES
ADON
VSS
CHS<3:0>
 2010 Microchip Technology Inc.
DS41430A-page 77
PIC16F/LF720/721
9.1
ADC Configuration
When changing channels, a delay is required before
starting the next conversion. Refer to Section 9.2
“ADC Operation” for more information.
When configuring and using the ADC the following
functions must be considered:
•
•
•
•
9.1.3
Port configuration
Channel selection
ADC conversion clock source
Interrupt control
9.1.1
•
•
•
•
•
•
•
PORT CONFIGURATION
When converting analog signals, the I/O pin selected
as the input channel should be configured for analog by
setting the associated TRIS and ANSEL bits. Refer to
Section 6.0 “I/O Ports” for more information.
Note:
Analog voltages on any pin that is defined
as a digital input may cause the input buffer to conduct excess current.
9.1.2
CONVERSION CLOCK
The source of the conversion clock is software
selectable via the ADCS bits of the ADCON1 register.
There are seven possible clock options:
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/32
FOSC/64
FRC (dedicated internal oscillator)
The time to complete one bit conversion is defined as
TAD. One full 8-bit conversion requires 10 TAD periods
as shown in Figure 9-2.
CHANNEL SELECTION
For correct conversion, the appropriate TAD
specification must be met. Refer to the A/D conversion
requirements
in
Section 23.0
“Electrical
Specifications” for more information. Table 9-1 gives
examples of appropriate ADC clock selections.
There are 14 channel selections available:
- AN<11:0> pins
- Temperature Indicator
- FVR (Fixed Voltage Reference) Output
Note:
Refer to Section 11.0 “Temperature Indicator Module” and Section 10.0 “Fixed Voltage Reference” for
more information on these channel selections.
Unless using the FRC, any changes in the
system clock frequency will change the
ADC clock frequency, which may
adversely affect the ADC result.
The CHS bits of the ADCON0 register determine which
channel is connected to the sample and hold circuit.
TABLE 9-1:
ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES
Device Frequency (FOSC)
ADC Clock Period (TAD)
ADC
Clock Source
ADCS<2:0>
16 MHz
8 MHz
4 MHz
1 MHz
FOSC/2
000
125 ns(2)
250 ns(2)
500 ns(2)
2.0 s
ns(2)
ns(2)
FOSC/4
100
250
1.0 s
4.0 s
FOSC/8
001
0.5 s(2)
1.0 s
2.0 s
8 s(5)
FOSC/16
101
1.0 s
2.0 s
4.0 s
16.0 s(5)
4.0 s
s(5)
32.0 s(3)
FOSC/32
010
2.0 s
FOSC/64
110
4.0 s
x11
1.0-6.0 s
FRC
Legend:
Note 1:
2:
3:
4:
5:
500
8
8 s(5)
(1,4)
1.0-6.0 s
(1,4)
16.0 s(5)
1.0-6.0 s
(1,4)
64.0 s(3)
1.0-6.0 s(1,4)
Shaded cells are outside of recommended range.
The FRC source has a typical TAD time of 1.6 s for VDD.
These values violate the minimum required TAD time.
For faster conversion times, the selection of another clock source is recommended.
When the device frequency is greater than 1 MHz, the FRC clock source is only recommended if the
conversion will be performed during Sleep.
Recommended values for VDD  2.0V and temperature -40°C to 85°C. The 16.0 s setting should be
avoided for temperature > 85°C.
DS41430A-page 78
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 9-2:
ANALOG-TO-DIGITAL CONVERSION TAD CYCLES
TCY to TAD
TAD0
TAD1
TAD2
TAD3
TAD4
TAD5
TAD6
TAD7
TAD8
TAD9
b7
b6
b5
b4
b3
b2
b1
b0
Conversion Starts
Holding Capacitor is disconnected from Analog Input (typically 100 ns)
Set GO/DONE bit
9.1.4
INTERRUPTS
The ADC module allows for the ability to generate an
interrupt upon completion of an Analog-to-Digital
conversion. The ADC Interrupt Flag is the ADIF bit in
the PIR1 register. The ADC Interrupt Enable is the
ADIE bit in the PIE1 register. The ADIF bit must be
cleared in software.
Note 1: The ADIF bit is set at the completion of
every conversion, regardless of whether
or not the ADC interrupt is enabled.
2: The ADC operates during Sleep only
when the FRC oscillator is selected.
This interrupt can be generated while the device is
operating or while in Sleep. If the device is in Sleep, the
interrupt will wake-up the device. Upon waking from
Sleep, the next instruction following the SLEEP
instruction is always executed. If the user is attempting
to wake-up from Sleep and resume in-line code
execution, the GIE and PEIE bits of the INTCON
register must be disabled. If the GIE and PEIE bits of
the INTCON register are enabled, execution will switch
to the Interrupt Service Routine.
Please refer to Section 9.1.4 “Interrupts” for more
information.
ADRES register is loaded,
GO/DONE bit is cleared,
ADIF bit is set,
Holding capacitor is connected to analog input
9.2
9.2.1
STARTING A CONVERSION
To enable the ADC module, the ADON bit of the
ADCON0 register must be set to a ‘1’. Setting the GO/
DONE bit of the ADCON0 register to a ‘1’ will start the
Analog-to-Digital conversion.
Note:
9.2.2
The GO/DONE bit should not be set in the
same instruction that turns on the ADC.
Refer to Section 9.2.6 “A/D Conversion
Procedure”.
COMPLETION OF A CONVERSION
When the conversion is complete, the ADC module will:
• Clear the GO/DONE bit
• Set the ADIF Interrupt Flag bit
• Update the ADRES register with new conversion
result
9.2.3
TERMINATING A CONVERSION
If a conversion must be terminated before completion,
the GO/DONE bit can be cleared in software. The
ADRES register will be updated with the partially complete Analog-to-Digital conversion sample. Incomplete
bits will match the last bit converted.
Note:
 2010 Microchip Technology Inc.
ADC Operation
A device Reset forces all registers to their
Reset state. Thus, the ADC module is
turned off and any pending conversion is
terminated.
DS41430A-page 79
PIC16F/LF720/721
9.2.4
ADC OPERATION DURING SLEEP
The ADC module can operate during Sleep. This
requires the ADC clock source to be set to the FRC
option. When the FRC clock source is selected, the
ADC waits one additional instruction before starting the
conversion. This allows the SLEEP instruction to be
executed, which can reduce system noise during the
conversion. If the ADC interrupt is enabled, the device
will wake-up from Sleep when the conversion
completes. If the ADC interrupt is disabled, the ADC
module is turned off after the conversion completes,
although the ADON bit remains set.
When the ADC clock source is something other than
FRC, a SLEEP instruction causes the present conversion to be aborted and the ADC module is turned off,
although the ADON bit remains set.
9.2.5
SPECIAL EVENT TRIGGER
The Special Event Trigger of the CCP module allows
periodic ADC measurements without software intervention. When this trigger occurs, the GO/DONE bit is
set by hardware and the Timer1 counter resets to zero.
Using the Special Event Trigger does not assure proper
ADC timing. It is the user’s responsibility to ensure that
the ADC timing requirements are met.
Refer to Section 15.0 “Capture/Compare/PWM
(CCP) Module” for more information.
9.2.6
A/D CONVERSION PROCEDURE
This is an example procedure for using the ADC to
perform an Analog-to-Digital conversion:
1.
2.
3.
Configure Port:
• Disable pin output driver (Refer to the TRIS
register)
• Configure pin as analog (Refer to the ANSEL
register)
Configure the ADC module:
• Select ADC conversion clock
• Select ADC input channel
• Turn on ADC module
Configure ADC interrupt (optional):
• Clear ADC interrupt flag
• Enable ADC interrupt
• Enable peripheral interrupt
• Enable global interrupt(1)
DS41430A-page 80
4.
5.
6.
7.
8.
Wait the required acquisition time(2).
Start conversion by setting the GO/DONE bit.
Wait for ADC conversion to complete by one of
the following:
• Polling the GO/DONE bit
• Waiting for the ADC interrupt (interrupts
enabled)
Read ADC Result.
Clear the ADC interrupt flag (required if interrupt
is enabled).
Note 1: The global interrupt can be disabled if the
user is attempting to wake-up from Sleep
and resume in-line code execution.
2: Refer to Section 9.3 “A/D Acquisition
Requirements”.
EXAMPLE 9-1:
A/D CONVERSION
;This code block configures the ADC
;for polling, Vdd reference, Frc clock
;and AN0 input.
;
;Conversion start & polling for completion
; are included.
;
BANKSEL
ADCON1
;
MOVLW
B’01110000’ ;ADC Frc clock,
;VDD reference
MOVWF
ADCON1
;
BANKSEL
TRISA
;
BSF
TRISA,0
;Set RA0 to input
BANKSEL
ANSELA
;
BSF
ANSELA,0
;Set RA0 to analog
BANKSEL
ADCON0
;
MOVLW
B’00000001’;AN0, On
MOVWF
ADCON0
;
CALL
SampleTime ;Acquisiton delay
BSF
ADCON0,GO ;Start conversion
BTFSC
ADCON0,GO ;Is conversion done?
GOTO
$-1
;No, test again
BANKSEL
ADRES
;
MOVF
ADRES,W
;Read result
MOVWF
RESULT
;store in GPR space
 2010 Microchip Technology Inc.
PIC16F/LF720/721
9.2.7
ADC REGISTER DEFINITIONS
The following registers are used to control the
operation of the ADC.
REGISTER 9-1:
ADCON0: A/D CONTROL REGISTER 0
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
Unimplemented: Read as ‘0’
bit 5-2
CHS<3:0>: Analog Channel Select bits
0000 = AN0
0001 = AN1
0010 = AN2
0011 = AN3
0100 = AN4
0101 = AN5
0110 = AN6
0111 = AN7
1000 = AN8
1001 = AN9
1010 = AN10
1011 = AN11
1110 = Temperature Indicator(1)
1111 = Fixed Voltage Reference (FVREF)(2)
bit 1
GO/DONE: A/D Conversion Status bit
1 = A/D conversion cycle in progress. Setting this bit starts an A/D conversion cycle.
This bit is automatically cleared by hardware when the A/D conversion has completed.
0 = A/D conversion completed/not in progress
bit 0
ADON: ADC Enable bit
1 = ADC is enabled
0 = ADC is disabled and consumes no operating current
Note 1:
2:
See Section 11.0 “Temperature Indicator Module” for more information.
See Section 10.0 “Fixed Voltage Reference” for more information.
 2010 Microchip Technology Inc.
DS41430A-page 81
PIC16F/LF720/721
REGISTER 9-2:
ADCON1: A/D CONTROL REGISTER 1
U-0
R/W-0
R/W-0
R/W-0
U-0
U-0
U-0
U-0
—
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
Unimplemented: Read as ‘0’
bit 6-4
ADCS<2:0>: A/D Conversion Clock Select bits
000 = FOSC/2
001 = FOSC/8
010 = FOSC/32
011 = FRC (clock supplied from a dedicated RC oscillator)
100 = FOSC/4
101 = FOSC/16
110 = FOSC/64
111 = FRC (clock supplied from a dedicated RC oscillator)
bit 3-0
Unimplemented: Read as ‘0’
REGISTER 9-3:
x = Bit is unknown
ADRES: ADC RESULT REGISTER
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
ADRES7
ADRES6
ADRES5
ADRES4
ADRES3
ADRES2
ADRES1
ADRES0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
x = Bit is unknown
ADRES<7:0>: ADC Result Register bits
8-bit conversion result.
DS41430A-page 82
 2010 Microchip Technology Inc.
PIC16F/LF720/721
9.3
A/D Acquisition Requirements
For the ADC to meet its specified accuracy, the charge
holding capacitor (CHOLD) must be allowed to fully
charge to the input channel voltage level. The Analog
Input model is shown in Figure 9-3. 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), refer
to Figure 9-3. The maximum recommended
impedance for analog sources is 10 k. As the
source impedance is decreased, the acquisition time
may be decreased. After the analog input channel is
EQUATION 9-1:
Assumptions:
selected (or changed), an A/D acquisition must be
done before the conversion can be started. To calculate
the minimum acquisition time, Equation 9-1 may be
used. This equation assumes that 1/2 LSb error is used
(256 steps for the ADC). The 1/2 LSb error is the
maximum error allowed for the ADC to meet its
specified resolution. It is noted that if the device is
operated at or below 2.0V VDD with the FRC clock
selected for the ADC and if the analog input changes
by more than 1 or 2 LSBs from the previous
conversion, then the use of at least 16 s TACQ time is
recommended.
ACQUISITION TIME EXAMPLE
Temperature = 50°C and external impedance of 10k  5.0V V DD
T ACQ = Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient
= T AMP + T C + T COFF
= 2µs + T C +   Temperature - 25°C   0.05µs/°C  
Note: TCOFF is zero for temperatures below 25 degrees C.
The value for TC can be approximated with the following equations:
1
 = V CHOLD
V AP P LI ED  1 – -------------------------n+1

2
–1
;[1] VCHOLD charged to within 1/2 lsb
–TC
----------

RC
V AP P LI ED  1 – e  = V CHOLD


;[2] VCHOLD charge response to VAPPLIED
– Tc
---------

RC
1
 ;combining [1] and [2]
V AP P LI ED  1 – e  = V A PP LIE D  1 – -------------------------n+1



2
–1
Note: Where n = number of bits of the ADC.
Solving for TC:
T C = – C HOLD  R IC + R SS + R S  ln(1/511)
= – 20pF  1k  + 7k  + 10k   ln(0.001957)
= 2.25 µs
Therefore:
T ACQ = 2µs + 2.25µs +   50°C- 25°C   0.05µs/°C  
= 5.5µs
 2010 Microchip Technology Inc.
DS41430A-page 83
PIC16F/LF720/721
Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out.
2: The charge holding capacitor (CHOLD) is not discharged after each conversion.
3: The maximum recommended impedance for analog sources is 10 k. This is required to meet the pin
leakage specification.
FIGURE 9-3:
ANALOG INPUT MODEL
VDD
Rs
VA
VT  0.6V
ANx
CPIN
5 pF
VT  0.6V
Sampling
Switch
SS Rss
RIC  1k
I LEAKAGE(1)
CHOLD = 20 pF
VSS
6V
Legend: CHOLD
CPIN
= Sample/Hold Capacitance
= Input Capacitance
VDD 4V
2V
I LEAKAGE = Leakage current at the pin due to
various junctions
RIC
= Interconnect Resistance
RSS
= Resistance of Sampling Switch
SS
= Sampling Switch
VT
= Threshold Voltage
5
10
15
20
Sampling Switch, Typical
(k)
Note 1: Refer to Section 23.0 “Electrical Specifications”.
FIGURE 9-4:
ADC TRANSFER FUNCTION
Full-Scale Range
FFh
FEh
FDh
ADC Output Code
FCh
1 LSB ideal
FBh
Full-Scale
Transition
04h
03h
02h
01h
00h
Analog Input Voltage
1 LSB ideal
VSS
DS41430A-page 84
Zero-Scale
Transition
VREF
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 9-2:
Name
SUMMARY OF ASSOCIATED ADC REGISTERS
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
ADCON0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
--00 0000
--00 0000
ADCON1
—
ADCS2
ADCS1
ADCS0
—
—
—
—
-000 ----
-000 ----
ANSELA
—
—
ANSA5
ANSA4
—
ANSA2
ANSA1
ANSA0
--11 -111
--11 -111
ANSELB
—
—
ANSB5
ANSB4
—
—
—
—
--11 ----
--11 ----
ANSELC
ANSC7
ANSC6
—
—
ANSC3
ANSC2
ANSC1
ANSC0
11-- 1111
11-- 1111
ADRES
FVRCON
INTCON
ADC Result Register
FVRRDY
FVREN
TSEN
TSRNG
—
—
ADFVR1
xxxx xxxx
uuuu uuuu
ADFVR0
q000 --00
q000 --00
0000 000x
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
TRISA
—
—
TRISA5
TRISA4
—
TRISA2
TRISA1
TRISA0
--11 -111
--11 -111
TRISB
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
1111 ----
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
TRISC
Legend:
x = unknown, u = unchanged, — = unimplemented read as ‘0’, q = value depends on condition. Shaded cells are not used for ADC
module.
 2010 Microchip Technology Inc.
DS41430A-page 85
PIC16F/LF720/721
NOTES:
DS41430A-page 86
 2010 Microchip Technology Inc.
PIC16F/LF720/721
10.0
FIXED VOLTAGE REFERENCE
This device contains an internal voltage regulator. To
provide a reference for the regulator, a band gap reference is provided. This band gap is also user accessible
via an A/D converter channel.
User level band gap functions are controlled by the
FVRCON register, which is shown in Register 10-1.
REGISTER 10-1:
FVRCON: FIXED VOLTAGE REFERENCE REGISTER
R-q
R/W-0
R/W-0
R/W-0
U-0
U-0
R/W-0
R/W-0
FVRRDY
FVREN
TSEN
TSRNG
—
—
ADFVR1
ADFVR0
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
q = Value depends on condition
bit 7
FVRRDY(1): Fixed Voltage Reference Ready Flag bit
0 = Fixed Voltage Reference output is not active or stable
1 = Fixed Voltage Reference output is ready for use
bit 6
FVREN(2): Fixed Voltage Reference Enable bit
0 = Fixed Voltage Reference is disabled
1 = Fixed Voltage Reference is enabled
bit 5
TSEN: Temperature Indicator Enable bit(3)
0 = Temperature indicator is disabled
1 = Temperature indicator is enabled
bit 4
TSRNG: Temperature Indicator Range Selection bit(3)
0 = VOUT = VDD - 4VT (High Range)
1 = VOUT = VDD - 2VT (Low Range)
bit 3-2
Unimplemented: Read as ‘0’
bit 1-0
ADFVR<1:0>: A/D Converter Fixed Voltage Reference Selection bits
00 = A/D Converter Fixed Voltage Reference Peripheral output is off
01 = A/D Converter Fixed Voltage Reference Peripheral output is 1x (1.024V)
10 = A/D Converter Fixed Voltage Reference Peripheral output is 2x (2.048V)(2)
11 = A/D Converter Fixed Voltage Reference Peripheral output is 4x (4.096V)(2)
Note 1:
2:
3:
FVRRDY is always ‘1’ for the PIC16F720/721 devices.
Fixed Voltage Reference output cannot exceed VDD.
See Section 11.0 “Temperature Indicator Module” for additional information.
TABLE 10-1:
Name
FVRCON
Legend:
SUMMARY OF ASSOCIATED FIXED VOLTAGE REFERENCE REGISTERS
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
FVRRDY
FVREN
TSEN
TSRNG
—
—
ADFVR1
Bit 0
Value on
POR, BOR
ADFVR0 q000 --00
Value on
all other
Resets
q000 --00
x = unknown, u = unchanged, — = unimplemented read as ‘0’, q = value depends on condition. Shaded cells are not
used for ADC module.
 2010 Microchip Technology Inc.
DS41430A-page 87
PIC16F/LF720/721
NOTES:
DS41430A-page 88
 2010 Microchip Technology Inc.
PIC16F/LF720/721
11.0
TEMPERATURE INDICATOR
MODULE
FIGURE 11-1:
This family of devices is equipped with a temperature
circuit designed to measure the operating temperature
of the silicon die. The circuit’s range of operating
temperature falls between -40°C and +85°C. The
output is a voltage that is proportional to the device
temperature. The output of the temperature indicator is
internally connected to the device ADC.
VDD
TSEN
TSRNG
The circuit may be used as a temperature threshold
detector or a more accurate temperature indicator,
depending on the level of calibration performed. A onepoint calibration allows the circuit to indicate a
temperature closely surrounding that point. A two-point
calibration allows the circuit to sense the entire range
of temperature more accurately. Reference Application
Note AN1333, “Use and Calibration of the Internal
Temperature Indicator” (DS01333) for more details
regarding the calibration process.
11.1
TEMPERATURE CIRCUIT
DIAGRAM
VOUT
ADC
MUX
ADC
n
CHS bits
(ADCON0 register)
Circuit Operation
Figure 11-1 shows a simplified block diagram of the
temperature circuit. The proportional voltage output is
achieved by measuring the forward voltage drop across
multiple silicon junctions.
Equation 11-1 describes the output characteristics of
the temperature indicator.
EQUATION 11-1:
VOUT RANGES
High Range: VOUT = VDD - 4VT
Low Range: VOUT = VDD - 2VT
11.2
Minimum Operating VDD vs.
Minimum Sensing Temperature
When the temperature circuit is operated in low range,
the device may be operated at any operating voltage
that is within specifications.
When the temperature circuit is operated in high range,
the device operating voltage, VDD, must be high
enough to ensure that the temperature circuit is
correctly biased.
Table 11-1 shows the recommended minimum VDD vs.
range setting.
TABLE 11-1:
The temperature sense circuit is integrated with the
Fixed Voltage Reference (FVR) module. See
Section 10.0 “Fixed Voltage Reference” for more
information.
The circuit is enabled by setting the TSEN bit of the
FVRCON register. When disabled, the circuit draws no
current.
The circuit operates in either high or low range. The high
range, selected by setting the TSRNG bit of the
FVRCON register, provides a wider output voltage. This
provides more resolution over the temperature range,
but may be less consistent from part to part. This range
requires a higher bias voltage to operate and thus, a
higher VDD is needed.
The low range is selected by clearing the TSRNG bit of
the FVRCON register. The low range generates a lower
voltage drop and thus, a lower bias voltage is needed to
operate the circuit. The low range is provided for low
voltage operation.
 2010 Microchip Technology Inc.
RECOMMENDED VDD VS.
RANGE
Min. VDD, TSRNG = 1
Min. VDD, TSRNG = 0
3.6V
1.8V
11.3
Temperature Output
The output of the circuit is measured using the internal
Analog-to-Digital converter. Channel 14 is reserved for
the temperature circuit output. Refer to Section 9.0
“Analog-to-Digital Converter (ADC) Module” for
detailed information.
Note:
Every time the ADC MUX is changed to
the temperature indicator output selection
(CHS bit in the ADCCON0 register), wait
500 usec for the sampling capacitor to
fully charge before sampling the temperature indicator output.
DS41430A-page 89
PIC16F/LF720/721
NOTES:
DS41430A-page 90
 2010 Microchip Technology Inc.
PIC16F/LF720/721
12.0
TIMER0 MODULE
12.1.1
The Timer0 module will increment every instruction
cycle, if used without a prescaler. 8-Bit Timer mode is
selected by clearing the T0CS bit of the OPTION
register.
The Timer0 module is an 8-bit timer/counter with the
following features:
•
•
•
•
•
•
8-bit timer/counter register (TMR0)
8-bit prescaler (shared with Watchdog Timer)
Programmable internal or external clock source
Programmable external clock edge selection
Interrupt on overflow
TMR0 can be used to gate Timer1
When TMR0 is written, the increment is inhibited for
two instruction cycles immediately following the write.
Note:
Figure 12-1 is a block diagram of the Timer0 module.
12.1
8-BIT TIMER MODE
12.1.2
Timer0 Operation
The value written to the TMR0 register
can be adjusted, in order to account for
the two instruction cycle delay when
TMR0 is written.
8-BIT COUNTER MODE
In 8-Bit Counter mode, the Timer0 module will increment
on every rising or falling edge of the T0CKI pin.
The Timer0 module can be used as either an 8-bit timer
or an 8-bit counter.
8-Bit Counter mode using the T0CKI pin is selected by
setting the T0CS bit in the OPTION register to ‘1’.
The rising or falling transition of the incrementing edge
for either input source is determined by the T0SE bit in
the OPTION register.
FIGURE 12-1:
BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
FOSC/4
Data Bus
0
8
T0CKI
1
SYNC
2 TCY
1
0
Set Flag bit T0IF
on Overflow
0
T0CS
T0SE
8-bit
Prescaler
PSA
Overflow to Timer1
1
T1GSS = 11
TMR0
TMR1GE
PSA
8
WDTE
Low-Power
WDT OSC
PS<2:0>
Divide by
512
1
WDT
Time-out
0
PSA
 2010 Microchip Technology Inc.
DS41430A-page 91
PIC16F/LF720/721
12.1.3
SOFTWARE PROGRAMMABLE
PRESCALER
A single software programmable prescaler is available
for use with either Timer0 or the Watchdog Timer
(WDT), but not both simultaneously. The prescaler
assignment is controlled by the PSA bit of the OPTION
register. To assign the prescaler to Timer0, the PSA bit
must be cleared to a ‘0’.
There are 8 prescaler options for the Timer0 module
ranging from 1:2 to 1:256. The prescale values are
selectable via the PS<2:0> bits of the OPTION register.
In order to have a 1:1 prescaler value for the Timer0
module, the prescaler must be assigned to the WDT
module.
The prescaler is not readable or writable. When
assigned to the Timer0 module, all instructions writing to
the TMR0 register will clear the prescaler.
Note:
When the prescaler is assigned to WDT, a
CLRWDT instruction will clear the prescaler
along with the WDT.
DS41430A-page 92
12.1.4
TIMER0 INTERRUPT
Timer0 will generate an interrupt when the TMR0
register overflows from FFh to 00h. The TMR0IF
interrupt flag bit of the INTCON register is set every
time the TMR0 register overflows, regardless of
whether or not the Timer0 interrupt is enabled. The
TMR0IF bit can only be cleared in software. The Timer0
interrupt enable is the TMR0IE bit of the INTCON
register.
Note:
12.1.5
The Timer0 interrupt cannot wake the
processor from Sleep since the timer is
frozen during Sleep.
8-BIT COUNTER MODE
SYNCHRONIZATION
When in 8-Bit Counter Mode, the incrementing edge on
the T0CKI pin must be synchronized to the instruction
clock. Synchronization can be accomplished by
sampling the prescaler output on the Q2 and Q4 cycles
of the instruction clock. The high and low periods of the
external clocking source must meet the timing
requirements as shown in Section 23.0 “Electrical
Specifications”.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 12-1:
OPTION_REG: OPTION 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
RABPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
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
RABPU: PORTA or PORTB Pull-up Enable bit
1 = PORTA or PORTB pull-ups are disabled
0 = PORTA or PORTB pull-ups are enabled by individual PORT latch values
bit 6
INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of INT pin
0 = Interrupt on falling edge of INT pin
bit 5
T0CS: TMR0 Clock Source Select bit
1 = Transition on T0CKI pin
0 = Internal instruction cycle clock (FOSC/4)
bit 4
T0SE: TMR0 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: Prescaler Assignment bit
1 = Prescaler is assigned to the WDT
0 = Prescaler is assigned to the Timer0 module
bit 2-0
PS<2:0>: Prescaler Rate Select bits
Bit Value
TMR0 Rate
1:2
1:4
1:8
1 : 16
1 : 32
1 : 64
1 : 128
1 : 256
000
001
010
011
100
101
110
111
TABLE 12-1:
Name
INTCON
Bit 6
Bit 5
Legend:
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
all other
Resets
Value on
POR, BOR
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
RABPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
1111 1111
1111 1111
xxxx xxxx
uuuu uuuu
—
—
TRISA5
TRISA2
TRISA1
TRISA0
--11 -111
--11 -111
TMR0
TRISA
1:1
1:2
1:4
1:8
1 : 16
1 : 32
1 : 64
1 : 128
SUMMARY OF REGISTERS ASSOCIATED WITH TIMER0
Bit 7
OPTION_REG
WDT Rate
Timer0 module Register
TRISA4
—
– = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the Timer0 module.
 2010 Microchip Technology Inc.
DS41430A-page 93
PIC16F/LF720/721
NOTES:
DS41430A-page 94
 2010 Microchip Technology Inc.
PIC16F/LF720/721
13.0
TIMER1 MODULE WITH GATE
CONTROL
•
•
•
•
The Timer1 module is a 16-bit timer/counter with the
following features:
Figure 13-1 is a block diagram of the Timer1 module.
•
•
•
•
•
•
•
16-bit timer/counter register pair (TMR1H:TMR1L)
Programmable internal or external clock source
3-bit prescaler
Synchronous or asynchronous operation
Multiple Timer1 gate (count enable) sources
Interrupt on overflow
Wake-up on overflow (external clock,
Asynchronous mode only)
• Time base for the Capture/Compare function
• Special Event Trigger (with CCP)
• Selectable Gate Source Polarity
FIGURE 13-1:
Gate Toggle Mode
Gate Single-pulse Mode
Gate Value Status
Gate Event Interrupt
TIMER1 BLOCK DIAGRAM
T1GSS<1:0>
T1G
00
From Timer0
Overflow
01
From Timer2
Match PR2
10
From WDT
Overflow
11
T1GSPM
0
T1G_IN
T1GVAL
0
D
Q
CK
R
Q
Single Pulse
Acq. Control
1
1
Q1
D
RD
T1GCON
EN
Interrupt
T1GGO/DONE
Set
TMR1GIF
det
T1GPOL
TMR1ON
T1GTM
Data Bus
Q
TMR1GE
TMR1ON
TMR1(2)
TMR1H
EN
T1CLK
TMR1L
Q
Synchronized
clock input
0
D
1
Set flag bit
TMR1IF on
Overflow
TMR1CS<1:0>
T1SYNC
(1)
10
T1CKI
Reserved
Synchronize(3)
Prescaler
1, 2, 4, 8
det
11
2
T1CKPS<1:0>
FOSC/4
Internal
Clock
00
FOSC
Internal
Clock
01
FOSC/2
Internal
Clock
Sleep input
Note 1: ST buffer is high speed type when using T1CKI.
2: Timer1 register increments on rising edge.
3: Synchronize does not operate while in Sleep.
 2010 Microchip Technology Inc.
DS41430A-page 95
PIC16F/LF720/721
13.1
Timer1 Operation
13.2
The Timer1 module is a 16-bit incrementing counter
which is accessed through the TMR1H:TMR1L register
pair. Writes to TMR1H or TMR1L directly update the
counter.
When used with an internal clock source, the module is
a timer and increments on every instruction cycle.
When used with an external clock source, the module
can be used as either a timer or counter and
increments on every selected edge of the external
source.
Timer1 is enabled by configuring the TMR1ON and
TMR1GE bits in the T1CON and T1GCON registers,
respectively. Table 13-1 displays the Timer1 enable
selections.
The TMR1CS<1:0> bits of the T1CON register are used
to select the clock source for Timer1. Table 13-2 displays
the clock source selections.
13.2.1
13.2.2
Timer1
Operation
TMR1GE
0
0
Off
0
1
Off
1
0
Always On
1
1
Count Enabled
TABLE 13-2:
EXTERNAL CLOCK SOURCE
When the external clock source is selected, the Timer1
module may work as a timer or a counter. When enabled
to count, Timer1 is incremented on the rising edge of the
external clock input T1CKI.
TIMER1 ENABLE
SELECTIONS
TMR1ON
INTERNAL CLOCK SOURCE
When the internal clock source is selected the
TMR1H:TMR1L register pair will increment on multiples
of FOSC as determined by the Timer1 prescaler.
Note:
TABLE 13-1:
Clock Source Selection
In Counter mode, a falling edge must be
registered by the counter prior to the first
incrementing rising edge after any one or
more of the following conditions:
•Timer1 enabled after POR Reset
•Write to TMR1H or TMR1L
•Timer1 is disabled
•Timer1 is disabled (TMR1ON = 0)
when T1CKI is high then Timer1 is
enabled (TMR1ON=1) when T1CKI is
low.
CLOCK SOURCE SELECTIONS
TMR1CS1
TMR1CS0
Clock Source
0
1
System Clock (FOSC)
0
0
Instruction Clock (FOSC/4)
1
0
External Clocking on T1CKI Pin
1
1
Reserved
DS41430A-page 96
 2010 Microchip Technology Inc.
PIC16F/LF720/721
13.3
Timer1 Prescaler
13.5
Timer1 Gate
Timer1 has four prescaler options allowing 1, 2, 4 or 8
divisions of the clock input. The T1CKPS bits of the
T1CON register control the prescale counter. The
prescale counter is not directly readable or writable;
however, the prescaler counter is cleared upon a write to
TMR1H or TMR1L.
Timer1 can be configured to count freely or the count
can be enabled and disabled using Timer1 gate
circuitry. This is also referred to as Timer1 gate count
enable.
13.4
13.5.1
Timer1 Operation in
Asynchronous Counter Mode
If control bit T1SYNC of the T1CON register is set, the
external clock input is not synchronized. The timer
increments asynchronously to the internal phase
clocks. If external clock source is selected then the
timer will continue to run during Sleep and can
generate an interrupt on overflow, which will wake-up
the processor. However, special precautions in
software are needed to read/write the timer (see
Section 13.4.1 “Reading and Writing Timer1 in
Asynchronous Counter Mode”).
Note:
13.4.1
When switching from synchronous to
asynchronous operation, it is possible to
skip an increment. When switching from
asynchronous to synchronous operation,
it is possible to produce an additional
increment.
READING AND WRITING TIMER1 IN
ASYNCHRONOUS COUNTER
MODE
Reading TMR1H or TMR1L while the timer is running
from an external asynchronous clock will ensure a valid
read (taken care of in hardware). However, the user
should keep in mind that reading the 16-bit timer in two
8-bit values itself, poses certain problems, since the
timer may overflow between the reads.
For writes, it is recommended that the user simply stop
the timer and write the desired values. A write
contention may occur by writing to the timer registers,
while the register is incrementing. This may produce an
unpredictable value in the TMR1H:TMR1L register pair.
 2010 Microchip Technology Inc.
Timer1 gate can also be driven by multiple selectable
sources.
TIMER1 GATE COUNT ENABLE
The Timer1 gate is enabled by setting the TMR1GE bit
of the T1GCON register. The polarity of the Timer1 gate
is configured using the T1GPOL bit of the T1GCON
register.
When Timer1 Gate (T1G) input is active, Timer1 will
increment on the rising edge of the Timer1 clock
source. When Timer1 gate input is inactive, no
incrementing will occur and Timer1 will hold the current
count. See Figure 13-3 for timing details.
TABLE 13-3:
TIMER1 GATE ENABLE
SELECTIONS
T1CLK
T1GPOL
T1G
Timer1 Operation

0
0
Counts

0
1
Holds Count

1
0
Holds Count

1
1
Counts
13.5.2
TIMER1 GATE SOURCE
SELECTION
The Timer1 gate source can be selected from one of
four different sources. Source selection is controlled by
the T1GSS bits of the T1GCON register. The polarity
for each available source is also selectable. Polarity
selection is controlled by the T1GPOL bit of the
T1GCON register.
TABLE 13-4:
T1GSS
TIMER1 GATE SOURCES
Timer1 Gate Source
00
Timer1 Gate Pin
01
Overflow of Timer0
(TMR0 increments from FFh to 00h)
10
Timer2 match PR2
(TMR2 increments to match PR2)
11
Count Enabled by WDT Overflow
(Watchdog Time-out interval expired)
DS41430A-page 97
PIC16F/LF720/721
13.5.2.1
T1G Pin Gate Operation
13.5.2.4
The T1G pin is one source for Timer1 gate control. It
can be used to supply an external source to the Timer1
gate circuitry.
13.5.2.2
Timer0 Overflow Gate Operation
When Timer0 increments from FFh to 00h, a low-tohigh pulse will automatically be generated and
internally supplied to the Timer1 gate circuitry.
13.5.2.3
Timer2 Match Gate Operation
The TMR2 register will increment until it matches the
value in the PR2 register. On the very next increment
cycle, TMR2 will be reset to 00h. When this Reset
occurs, a low-to-high pulse will automatically be
generated and internally supplied to the Timer1 gate
circuitry.
Watchdog Overflow Gate Operation
The Watchdog Timer oscillator, prescaler and counter
will be automatically turned on when TMR1GE = 1 and
T1GSS selects the WDT as a gate source for Timer1
(T1GSS = 11). TMR1ON does not factor into the oscillator, prescaler and counter enable. See Table 13-5.
The PSA and PS bits of the OPTION register still
control what time-out interval is selected. Changing the
prescaler during operation may result in a spurious
capture.
Enabling the Watchdog Timer oscillator does not
automatically enable a Watchdog Reset or Wake-up
from Sleep upon counter overflow.
Note:
When using the WDT as a gate source for
Timer1, operations that clear the Watchdog
Timer (CLRWDT, SLEEP instructions) will
affect the time interval being measured.
This includes waking from Sleep. All other
interrupts that might wake the device from
Sleep should be disabled to prevent them
from disturbing the measurement period.
As the gate signal coming from the WDT counter will
generate different pulse widths depending on if the
WDT is enabled, when the CLRWDT instruction is
executed, and so on, Toggle mode must be used. A
specific sequence is required to put the device into the
correct state to capture the next WDT counter interval.
TABLE 13-5:
WDT/TIMER1 GATE INTERACTION
WDTE
TMR1GE = 1
and
T1GSS = 11
WDT Oscillator
Enable
WDT Reset
Wake-up
WDT Available for
T1G Source
1
N
Y
Y
Y
N
1
Y
Y
Y
Y
Y
0
Y
Y
N
N
Y
0
N
N
N
N
N
DS41430A-page 98
 2010 Microchip Technology Inc.
PIC16F/LF720/721
13.5.3
TIMER1 GATE TOGGLE MODE
When Timer1 Gate Toggle mode is enabled, it is
possible to measure the full-cycle length of a Timer1
gate signal, as opposed to the duration of a single level
pulse.
The Timer1 gate source is routed through a flip-flop that
changes state on every incrementing edge of the signal. See Figure 13-4 for timing details.
Timer1 Gate Toggle mode is enabled by setting the
T1GTM bit of the T1GCON register. When the T1GTM
bit is cleared, the flip-flop is cleared and held clear. This
is necessary in order to control which edge is
measured.
Note:
13.5.4
Enabling Toggle mode at the same time
as changing the gate polarity may result in
indeterminate operation.
13.5.5
TIMER1 GATE VALUE STATUS
When Timer1 gate value status is utilized, it is possible
to read the most current level of the gate control value.
The value is stored in the T1GVAL bit in the T1GCON
register. The T1GVAL bit is valid even when the Timer1
gate is not enabled (TMR1GE bit is cleared).
13.5.6
TIMER1 GATE EVENT INTERRUPT
When Timer1 gate event interrupt is enabled, it is
possible to generate an interrupt upon the completion
of a gate event. When the falling edge of T1GVAL
occurs, the TMR1GIF flag bit in the PIR1 register will be
set. If the TMR1GIE bit in the PIE1 register is set, then
an interrupt will be recognized.
The TMR1GIF flag bit operates even when the Timer1
gate is not enabled (TMR1GE bit is cleared).
TIMER1 GATE SINGLE-PULSE
MODE
When Timer1 Gate Single-Pulse mode is enabled, it is
possible to capture a single pulse gate event. Timer1
Gate Single-Pulse mode is first enabled by setting the
T1GSPM bit in the T1GCON register. Next, the
T1GGO/DONE bit in the T1GCON register must be set.
The Timer1 will be fully enabled on the next
incrementing edge. On the next trailing edge of the
pulse, the T1GGO/DONE bit will automatically be
cleared. No other gate events will be allowed to
increment Timer1 until the T1GGO/DONE bit is once
again set in software.
Clearing the T1GSPM bit of the T1GCON register will
also clear the T1GGO/DONE bit. See Figure 13-5 for
timing details.
Enabling the Toggle mode and the Single-Pulse mode
simultaneously will permit both sections to work
together. This allows the cycle times on the Timer1 gate
source to be measured. See Figure 13-6 for timing
details.
 2010 Microchip Technology Inc.
DS41430A-page 99
PIC16F/LF720/721
13.6
Timer1 Interrupt
The Timer1 register pair (TMR1H:TMR1L) increments
to FFFFh and rolls over to 0000h. When Timer1 rolls
over, the Timer1 interrupt flag bit of the PIR1 register is
set. To enable the interrupt on rollover, you must set
these bits:
•
•
•
•
TMR1ON bit of the T1CON register
TMR1IE bit of the PIE1 register
PEIE bit of the INTCON register
GIE bit of the INTCON register
The interrupt is cleared by clearing the TMR1IF bit in
the Interrupt Service Routine.
Note:
13.7
The TMR1H:TMR1L register pair and the
TMR1IF bit should be cleared before
enabling interrupts.
Timer1 Operation During Sleep
Timer1 can only operate during Sleep when setup in
Asynchronous Counter mode. In this mode, the clock
source can be used to increment the counter. To set up
the timer to wake the device:
•
•
•
•
•
TMR1ON bit of the T1CON register must be set
TMR1IE bit of the PIE1 register must be set
PEIE bit of the INTCON register must be set
T1SYNC bit of the T1CON register must be set
TMR1CS bits of the T1CON register must be
configured
• TMR1GE bit of the T1GCON register must be
configured
The device will wake-up on an overflow and execute
the next instructions. If the GIE bit of the INTCON
register is set, the device will call the Interrupt Service
Routine (0004h).
FIGURE 13-2:
13.8
CCP Capture/Compare Time Base
The CCP module uses the TMR1H:TMR1L register
pair as the time base when operating in Capture or
Compare mode.
In Capture mode, the value in the TMR1H:TMR1L
register pair is copied into the CCPR1H:CCPR1L
register pair on a configured event.
In Compare mode, an event is triggered when the value
CCPR1H:CCPR1L register pair matches the value in
the TMR1H:TMR1L register pair. This event can be a
Special Event Trigger.
For more information, see Section 15.0 “Capture/
Compare/PWM (CCP) Module”.
13.9
CCP Special Event Trigger
When the CCP is configured to trigger a special event,
the trigger will clear the TMR1H:TMR1L register pair.
This special event does not cause a Timer1 interrupt.
The CCP module may still be configured to generate a
CCP interrupt.
In this mode of operation, the CCPR1H:CCPR1L
register pair becomes the period register for Timer1.
Timer1 should be synchronized to the FOSC/4 to utilize
the Special Event Trigger. Asynchronous operation of
Timer1 can cause a Special Event Trigger to be
missed.
In the event that a write to TMR1H or TMR1L coincides
with a Special Event Trigger from the CCP, the write will
take precedence.
For more information, see Section 9.2.5 “Special
Event Trigger”.
TIMER1 INCREMENTING EDGE
T1CKI = 1
when TMR1
Enabled
T1CKI = 0
when TMR1
Enabled
Note 1:
2:
Arrows indicate counter increments.
In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge of the clock.
DS41430A-page 100
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 13-3:
TIMER1 GATE COUNT ENABLE MODE
TMR1GE
T1GPOL
T1G_IN
T1CKI
T1GVAL
TIMER1
N
FIGURE 13-4:
N+1
N+2
N+3
N+4
TIMER1 GATE TOGGLE MODE
TMR1GE
T1GPOL
T1GTM
T1G_IN
T1CKI
T1GVAL
TIMER1
N
 2010 Microchip Technology Inc.
N+1 N+2 N+3
N+4
N+5 N+6 N+7
N+8
DS41430A-page 101
PIC16F/LF720/721
FIGURE 13-5:
TIMER1 GATE SINGLE-PULSE MODE
TMR1GE
T1GPOL
T1GSPM
T1GGO/
Cleared by hardware on
falling edge of T1GVAL
Set by software
DONE
Counting enabled on
rising edge of T1G
T1G_IN
T1CKI
T1GVAL
TIMER1
TMR1GIF
DS41430A-page 102
N
Cleared by software
N+1
N+2
Set by hardware on
falling edge of T1GVAL
Cleared by
software
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 13-6:
TIMER1 GATE SINGLE-PULSE AND TOGGLE COMBINED MODE
TMR1GE
T1GPOL
T1GSPM
T1GTM
T1GGO/
Cleared by hardware on
falling edge of T1GVAL
Set by software
DONE
Counting enabled on
rising edge of T1G
T1G_IN
T1CKI
T1GVAL
TIMER1
TMR1GIF
N
Cleared by software
 2010 Microchip Technology Inc.
N+1
N+2
N+3
Set by hardware on
falling edge of T1GVAL
N+4
Cleared by
software
DS41430A-page 103
PIC16F/LF720/721
13.10 Timer1 Control Register
The Timer1 Control register (T1CON), shown in
Register 13-1, is used to control Timer1 and select the
various features of the Timer1 module.
REGISTER 13-1:
T1CON: TIMER1 CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
U-0
R/W-0
U-0
R/W-0
TMR1CS1
TMR1CS0
T1CKPS1
T1CKPS0
—
T1SYNC
—
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 7-6
TMR1CS<1:0>: Timer1 Clock Source Select bits
11 = Reserved
10 = Timer1 clock source is pin or oscillator. External clock from T1CKI pin (on the rising edge)
01 = Timer1 clock source is system clock (FOSC)
00 = Timer1 clock source is instruction clock (FOSC/4)
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
Unimplemented: Read as ‘0’
bit 2
T1SYNC: Timer1 External Clock Input Synchronization Control bit
TMR1CS<1:0> = 1X
1 = Do not synchronize external clock input
0 = Synchronize external clock input with system clock (FOSC)
TMR1CS<1:0> = 0X
This bit is ignored. Timer1 uses the internal clock when TMR1CS<1:0> = 1X.
bit 1
Unimplemented: Read as ‘0’
bit 0
TMR1ON: Timer1 On bit
1 = Enables Timer1
0 = Stops Timer1
Clears Timer1 gate flip-flop
DS41430A-page 104
 2010 Microchip Technology Inc.
PIC16F/LF720/721
13.11 Timer1 Gate Control Register
The Timer1 Gate Control register (T1GCON), shown in
Register 13-2, is used to control Timer1 gate.
REGISTER 13-2:
T1GCON: TIMER1 GATE CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R-x
R/W-0
R/W-0
TMR1GE
T1GPOL
T1GTM
T1GSPM
T1GGO/
DONE
T1GVAL
T1GSS1
T1GSS0
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
TMR1GE: Timer1 Gate Enable bit
If TMR1ON = 0:
This bit is ignored
If TMR1ON = 1:
1 = Timer1 counting is controlled by the Timer1 gate function
0 = Timer1 counts regardless of Timer1 gate function
bit 6
T1GPOL: Timer1 Gate Polarity bit
1 = Timer1 gate is active-high (Timer1 counts when gate is high)
0 = Timer1 gate is active-low (Timer1 counts when gate is low)
bit 5
T1GTM: Timer1 Gate Toggle mode bit
1 = Timer1 Gate Toggle mode is enabled.
0 = Timer1 Gate Toggle mode is disabled and toggle flip-flop is cleared
Timer1 gate flip-flop toggles on every rising edge.
bit 4
T1GSPM: Timer1 Gate Single Pulse mode bit
1 = Timer1 Gate Single-Pulse mode is enabled and is controlling Timer1 gate
0 = Timer1 Gate Single-Pulse mode is disabled
bit 3
T1GGO/DONE: Timer1 Gate Single-Pulse Acquisition Status bit
1 = Timer1 gate single-pulse acquisition is ready, waiting for an edge
0 = Timer1 gate single-pulse acquisition has completed or has not been started
This bit is automatically cleared when T1GSPM is cleared.
bit 2
T1GVAL: Timer1 Gate Current State bit
Indicates the current state of the Timer1 gate that could be provided to TMR1H:TMR1L.
Unaffected by Timer1 Gate Enable (TMR1GE).
bit 1-0
T1GSS<1:0>: Timer1 Gate Source Select bits
00 = Timer1 gate pin
01 = Timer0 overflow output
10 = TMR2 match PR2 output
11 = Watchdog Timer scaler overflow
Watchdog Timer oscillator is turned on if TMR1GE = 1, regardless of the state of TMR1ON
 2010 Microchip Technology Inc.
DS41430A-page 105
PIC16F/LF720/721
TABLE 13-6:
Name
SUMMARY OF REGISTERS ASSOCIATED WITH TIMER1
Bit 2
Bit 1
Bit 0
Value on
all other
Resets
Bit 6
Bit 5
Bit 4
ANSELB
—
—
ANSB5
ANSB4
—
—
—
—
--11 ----
--11 ----
CCP1CON
—
—
DC1
B1
CCP1M3
CCP1M2
CCP1M1
CCP1M0
--00 0000
--00 0000
0000 000x
INTCON
Bit 3
Value on
POR, BOR
Bit 7
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
RB6
RB5
RB4
—
—
—
—
PORTB
RB7
xxxx ----
uuuu ----
TMR1H
Holding Register for the Most Significant Byte of the 16-bit TMR1 Register
xxxx xxxx
uuuu uuuu
TMR1L
Holding Register for the Least Significant Byte of the 16-bit TMR1 Register
xxxx xxxx
uuuu uuuu
1111 ----
TRISB
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
T1CKPS1
T1CKPS0
—
T1SYNC
—
TMR1ON
0000 -0-0
uuuu -u-u
T1GTM
T1GSPM
T1GGO/
DONE
T1GVAL
T1GSS1
T1GSS0
0000 0x00
uuuu uxuu
T1CON
TMR1CS1 TMR1CS0
T1GCON
TMR1GE
Legend:
x = unknown, u = unchanged, — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer1 module.
DS41430A-page 106
T1GPOL
 2010 Microchip Technology Inc.
PIC16F/LF720/721
14.0
TIMER2 MODULE
The Timer2 module is an 8-bit timer with the following
features:
•
•
•
•
•
8-bit timer register (TMR2)
8-bit period register (PR2)
Interrupt on TMR2 match with PR2
Software programmable prescaler (1:1, 1:4, 1:16)
Software programmable postscaler (1:1 to 1:16)
Timer2 is turned on by setting the TMR2ON bit in the
T2CON register to a ‘1’. Timer2 is turned off by clearing
the TMR2ON bit to a ‘0’.
The Timer2 prescaler is controlled by the T2CKPS bits
in the T2CON register. The Timer2 postscaler is
controlled by the TOUTPS bits in the T2CON register.
The prescaler and postscaler counters are cleared
when:
See Figure 14-1 for a block diagram of Timer2.
14.1
The TMR2 and PR2 registers are both fully readable
and writable. On any Reset, the TMR2 register is set to
00h and the PR2 register is set to FFh.
Timer2 Operation
The clock input to the Timer2 module is the system
instruction clock (FOSC/4). The clock is fed into the
Timer2 prescaler, which has prescale options of 1:1,
1:4 or 1:16. The output of the prescaler is then used to
increment the TMR2 register.
• A write to TMR2 occurs.
• A write to T2CON occurs.
• Any device Reset occurs (Power-on Reset, MCLR
Reset, Watchdog Timer Reset, or Brown-out
Reset).
Note:
The values of TMR2 and PR2 are constantly compared
to determine when they match. TMR2 will increment
from 00h until it matches the value in PR2. When a
match occurs, two things happen:
TMR2 is not cleared when T2CON is
written.
• TMR2 is reset to 00h on the next increment cycle.
• The Timer2 postscaler is incremented.
The match output of the Timer2/PR2 comparator is
then fed into the Timer2 postscaler. The postscaler has
postscale options of 1:1 to 1:16 inclusive. The output of
the Timer2 postscaler is used to set the TMR2IF
interrupt flag bit in the PIR1 register.
FIGURE 14-1:
TIMER2 BLOCK DIAGRAM
TMR2
Output
FOSC/4
Prescaler
1:1, 1:4, 1:16
2
TMR2
Sets Flag
bit TMR2IF
Reset
Comparator
EQ
Postscaler
1:1 to 1:16
T2CKPS<1:0>
PR2
4
TOUTPS<3:0>
 2010 Microchip Technology Inc.
DS41430A-page 107
PIC16F/LF720/721
REGISTER 14-1:
T2CON: TIMER2 CONTROL REGISTER
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
TOUTPS3
TOUTPS2
TOUTPS1
TOUTPS0
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
TOUTPS<3:0>: Timer2 Output Postscaler Select bits
0000 = 1:1 Postscaler
0001 = 1:2 Postscaler
0010 = 1:3 Postscaler
0011 = 1:4 Postscaler
0100 = 1:5 Postscaler
0101 = 1:6 Postscaler
0110 = 1:7 Postscaler
0111 = 1:8 Postscaler
1000 = 1:9 Postscaler
1001 = 1:10 Postscaler
1010 = 1:11 Postscaler
1011 = 1:12 Postscaler
1100 = 1:13 Postscaler
1101 = 1:14 Postscaler
1110 = 1:15 Postscaler
1111 = 1:16 Postscaler
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
TABLE 14-1:
Name
x = Bit is unknown
SUMMARY OF REGISTERS ASSOCIATED WITH TIMER2
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
Timer2 module Period Register
1111 1111
1111 1111
Timer2 module Register
0000 0000
0000 0000
-000 0000
-000 0000
INTCON
PR2
TMR2
T2CON
Legend:
—
TOUTPS3
TOUTPS2
TOUTPS1
TOUTPS0
TMR2ON
T2CKPS1
T2CKPS0
x = unknown, u = unchanged, - = unimplemented read as ‘0’. Shaded cells are not used for Timer2 module.
DS41430A-page 108
 2010 Microchip Technology Inc.
PIC16F/LF720/721
15.0
CAPTURE/COMPARE/PWM
(CCP) MODULE
TABLE 15-1:
The Capture/Compare/PWM module is a peripheral
which allows the user to time and control different
events. In Capture mode, the peripheral allows the
timing of the duration of an event. The Compare mode
allows the user to trigger an external event when a
predetermined amount of time has expired. The PWM
mode can generate a Pulse-Width Modulated signal of
varying frequency and duty cycle.
CCP MODE – TIMER
RESOURCES REQUIRED
CCP Mode
Timer Resource
Capture
Timer1
Compare
Timer1
PWM
Timer2
The timer resources used by the module are shown in
Table 15-1.
Additional information on CCP modules is available in
the Application Note AN594, “Using the CCP Modules”
(DS00594).
REGISTER 15-1:
CCP1CON: CCP1 CONTROL REGISTER
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
DC1
B1
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
Unimplemented: Read as ‘0’
bit 5-4
DC1:B1: PWM Duty Cycle Least Significant bits
Capture mode:
Unused
Compare mode:
Unused
PWM mode:
These bits are the two LSbs of the PWM duty cycle. The eight MSbs are found in CCPR1L.
bit 3-0
CCP1M<3:0>: CCP mode Select bits
0000 = Capture/Compare/PWM off (resets CCP module)
0001 = Unused (reserved)
0010 = Compare mode, toggle output on match (CCP1IF bit of the PIRx register is set)
0011 = Unused (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, set output on match (CCP1IF bit of the PIR1 register is set)
1001 = Compare mode, clear output on match (CCP1IF bit of the PIR1 register is set)
1010 = Compare mode, generate software interrupt on match (CCP1IF bit is set of the PIRx register,
CCP1 pin is unaffected)
1011 = Compare mode, trigger special event (CCP1IF bit of the PIR1register is set, TMR1 is reset
and A/D conversion is started if the ADC module is enabled. CCP1 pin is unaffected.)
11xx = PWM mode.
 2010 Microchip Technology Inc.
DS41430A-page 109
PIC16F/LF720/721
15.1
15.1.3
Capture Mode
In Capture mode, CCPR1H:CCPR1L captures the
16-bit value of the TMR1 register when an event occurs
on pin CCP1. An event is defined as one of the
following and is configured by the CCP1M<3:0> bits of
the CCP1CON register:
•
•
•
•
Every falling edge
Every rising edge
Every 4th rising edge
Every 16th rising edge
15.1.1
CCP1 PIN CONFIGURATION
In Capture mode, the CCP1 pin should be configured
as an input by setting the associated TRIS control bit.
Note:
If the CCP1 pin is configured as an output,
a write to the port can cause a capture
condition.
FIGURE 15-1:
Prescaler
 1, 4, 16
CAPTURE MODE
OPERATION BLOCK
DIAGRAM
Set Flag bit CCP1IF
(PIR1 register)
CCP1
CCPR1H
and
Edge Detect
CCPR1L
Capture
Enable
TMR1H
TMR1L
TIMER1 MODE SELECTION
Timer1 must be running in Timer mode or Synchronized
Counter mode for the CCP module to use the capture
feature. In Asynchronous Counter mode or when
Timer1 is clocked at FOSC, the capture operation may
not work.
Note:
CCP PRESCALER
There are four prescaler settings specified by the
CCP1M<3:0> bits of the CCP1CON register.
Whenever the CCP module is turned off, or the CCP
module is not in Capture mode, the prescaler counter
is cleared. Any Reset will clear the prescaler counter.
Switching from one capture prescaler to another does not
clear the prescaler and may generate a false interrupt. To
avoid this unexpected operation, turn the module off by
clearing the CCP1CON register before changing the
prescaler (refer to Example 15-1).
EXAMPLE 15-1:
CHANGING BETWEEN
CAPTURE PRESCALERS
BANKSEL CCP1CON
CLRF
MOVLW
MOVWF
15.1.5
CCP1CON<3:0>
System Clock (FOSC)
15.1.2
When the Capture mode is changed, a false capture
interrupt may be generated. The user should keep the
CCP1IE interrupt enable bit of the PIE1 register clear to
avoid false interrupts. Additionally, the user should
clear the CCP1IF interrupt flag bit of the PIR1 register
following any change in operating mode
15.1.4
When a capture is made, the Interrupt Request Flag bit
CCP1IF of the PIR1 register is set. The interrupt flag
must be cleared in software. If another capture occurs
before the value in the CCPR1H, CCPR1L register pair
is read, the old captured value is overwritten by the new
captured value (refer to Figure 15-1).
SOFTWARE INTERRUPT
;Set Bank bits to point
;to CCP1CON
CCP1CON
;Turn CCP module off
NEW_CAPT_PS ;Load the W reg with
; the new prescaler
; move value and CCP ON
CCP1CON
;Load CCP1CON with this
; value
CAPTURE DURING SLEEP
Capture mode depends upon the Timer1 module for
proper operation. There are two options for driving the
Timer1 module in Capture mode. It can be driven by the
instruction clock (FOSC/4), or by an external clock
source.
If Timer1 is clocked by FOSC/4, then Timer1 will not
increment during Sleep. When the device wakes from
Sleep, Timer1 will continue from its previous state.
If Timer1 is clocked by an external clock source, then
Capture mode will operate as defined in Section 15.1
“Capture Mode”.
Clocking Timer1 from the system clock
(FOSC) should not be used in Capture
mode. In order for Capture mode to
recognize the trigger event on the CCP1
pin, Timer1 must be clocked from the
Instruction Clock (FOSC/4) or from an
external clock source.
DS41430A-page 110
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 15-2:
Name
SUMMARY OF REGISTERS ASSOCIATED WITH CAPTURE
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
Bit 7
Bit 6
Bit 5
Bit 4
ANSELB
—
—
ANSB5
ANSB4
—
—
—
—
--11 ----
--11 ----
CCP1CON
—
—
DC1
B1
CCP1M3
CCP1M2
CCP1M1
CCP1M0
--00 0000
--00 0000
uuuu uuuu
CCPR1L
Capture/Compare/PWM Register Low Byte
xxxx xxxx
CCPR1H
Capture/Compare/PWM Register High Byte
xxxx xxxx
uuuu uuuu
INTCON
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
T1CON
TMR1CS1
TMR1CS0
T1CKPS1
T1CKPS0
—
T1SYNC
—
TMR1ON
0000 -0-0
uuuu -u-u
T1GCON
TMR1GE
T1GPOL
T1GTM
T1GSPM
T1GGO/
DONE
T1GVAL
T1GSS1
T1GSS0
0000 0x00
uuuu uxuu
uuuu uuuu
TMR1L
Holding Register for the Least Significant Byte of the 16-bit TMR1 Register
xxxx xxxx
TMR1H
Holding Register for the Most Significant Byte of the 16-bit TMR1 Register
xxxx xxxx
uuuu uuuu
TRISB
TRISC
Legend:
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
1111 ----
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
- = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the capture.
 2010 Microchip Technology Inc.
DS41430A-page 111
PIC16F/LF720/721
15.2
15.2.2
Compare Mode
In Compare mode, the 16-bit CCPR1 register value is
constantly compared against the TMR1 register pair
value. When a match occurs, the CCP1 module may:
•
•
•
•
•
Toggle the CCP1 output
Set the CCP1 output
Clear the CCP1 output
Generate a Special Event Trigger
Generate a Software Interrupt
In Compare mode, Timer1 must be running in either
Timer mode or Synchronized Counter mode. The
compare operation may not work in Asynchronous
Counter mode.
Note:
The action on the pin is based on the value of the
CCP1M<3:0> control bits of the CCP1CON register.
All Compare modes can generate an interrupt.
FIGURE 15-2:
COMPARE MODE
OPERATION BLOCK
DIAGRAM
CCP1CON<3:0>
Mode Select
Set CCP1IF Interrupt Flag
(PIR1)
4
CCPR1H CCPR1L
CCP1
Q
S
R
Output
Logic
Match
TRIS
Output Enable
Comparator
TMR1H
TMR1L
Special Event Trigger
Special Event Trigger will:
• Clear TMR1H and TMR1L registers.
• NOT set interrupt flag bit TMR1IF of the PIR1 register.
• Set the GO/DONE bit to start the ADC conversion.
15.2.1
CCP1 PIN CONFIGURATION
The user must configure the CCP1 pin as an output by
clearing the associated TRIS bit.
Note:
Clearing the CCP1CON register will force
the CCP1 compare output latch to the
default low level. This is not the PORT I/O
data latch.
TIMER1 MODE SELECTION
15.2.3
Clocking Timer1 from the system clock
(FOSC) should not be used in Compare
mode. For the Compare operation of the
TMR1 register to the CCPR1 register to
occur, Timer1 must be clocked from the
instruction clock (FOSC/4) or from an
external clock source.
SOFTWARE INTERRUPT MODE
When Software Interrupt mode is chosen
(CCP1M<3:0> = 1010), the CCP1IF bit in the PIR1
register is set and the CCP1 module does not assert
control of the CCP1 pin (refer to the CCP1CON
register).
15.2.4
SPECIAL EVENT TRIGGER
When Special Event Trigger mode is chosen
(CCP1M<3:0> = 1011), the CCP1 module does the
following:
• Resets Timer1
• Starts an ADC conversion if ADC is enabled
The CCP1 module does not assert control of the CCP1
pin in this mode (refer to the CCP1CON register).
The Special Event Trigger output of the CCP occurs
immediately upon a match between the TMR1H,
TMR1L register pair and the CCPR1H, CCPR1L
register pair. The TMR1H, TMR1L register pair is not
reset until the next rising edge of the Timer1 clock. This
allows the CCPR1H, CCPR1L register pair to
effectively provide a 16-bit programmable period
register for Timer1.
Note 1: The Special Event Trigger from the CCP
module does not set interrupt flag bit
TMR1IF of the PIR1 register.
2: Removing the match condition by
changing the contents of the CCPR1H
and CCPR1L register pair, between the
clock edge that generates the Special
Event Trigger and the clock edge that
generates the Timer1 Reset, will
preclude the Reset from occurring.
15.2.5
COMPARE DURING SLEEP
The Compare mode is dependent upon the system
clock (FOSC) for proper operation. Since FOSC is shut
down during Sleep mode, the Compare mode will not
function properly during Sleep.
DS41430A-page 112
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 15-3:
Name
SUMMARY OF REGISTERS ASSOCIATED WITH COMPARE
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
ADCON0
—
—
CHS3
CHS2
CHS1
CHS0
GO/DONE
ADON
--00 0000
--00 0000
ANSELB
—
—
ANSB5
ANSB4
—
—
—
—
--11 ----
--11 ----
CCP1CON
—
—
DC1
B1
CCP1M3
CCP1M2
CCP1M1
CCP1M0
--00 0000
--00 0000
CCPR1L
Capture/Compare/PWM Register Low Byte
xxxx xxxx
uuuu uuuu
CCPR1H
Capture/Compare/PWM Register High Byte
xxxx xxxx
uuuu uuuu
INTCON
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
T1CON
TMR1CS1
TMR1CS0
T1CKPS1
T1CKPS0
—
T1SYNC
—
TMR1ON
0000 -0-0
uuuu -u-u
T1GCON
TMR1GE
T1GPOL
T1GTM
T1GSPM
T1GGO/
DONE
T1GVAL
T1GSS1
T1GSS0
0000 0x00
uuuu uxuu
uuuu uuuu
TMR1L
Holding Register for the Least Significant Byte of the 16-bit TMR1 Register
xxxx xxxx
TMR1H
Holding Register for the Most Significant Byte of the 16-bit TMR1 Register
xxxx xxxx
uuuu uuuu
TRISB
TRISC
Legend:
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
1111 ----
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
- = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the compare.
 2010 Microchip Technology Inc.
DS41430A-page 113
PIC16F/LF720/721
15.3
PWM Mode
The PWM mode generates a Pulse-Width Modulated
signal on the CCP1 pin. The duty cycle, period and
resolution are determined by the following registers:
•
•
•
•
The PWM output (Figure 15-4) has a time base
(period) and a time that the output stays high (duty
cycle).
FIGURE 15-4:
PR2
T2CON
CCPR1L
CCP1CON
CCP PWM OUTPUT
Period
Pulse Width
In Pulse-Width Modulation (PWM) mode, the CCP
module produces up to a 10-bit resolution PWM output
on the CCP1 pin.
TMR2 = PR2
TMR2 = CCPR1L:CCP1CON<5:4>
TMR2 = 0
Figure 15-3 shows a simplified block diagram of PWM
operation.
15.3.1
Figure 15-4 shows a typical waveform of the PWM
signal.
In PWM mode, the CCP1 pin is multiplexed with the
PORT data latch. The user must configure the CCP1
pin as an output by clearing the associated TRIS bit.
For a step-by-step procedure on how to set up the CCP
module for PWM operation, refer to Section 15.3.8
“Setup for PWM Operation”.
FIGURE 15-3:
Note:
CCPX PIN CONFIGURATION
Clearing the CCP1CON register will
relinquish CCP1 control of the CCP1 pin.
SIMPLIFIED PWM BLOCK
DIAGRAM
CCP1CON<5:4>
Duty Cycle Registers
CCPR1L
CCPR1H(2) (Slave)
CCP1
R
Comparator
TMR2
(1)
Q
S
TRIS
Comparator
PR2
Note
1:
2:
Clear Timer2,
toggle CCP1 pin and
latch duty cycle
The 8-bit timer TMR2 register is concatenated with
the 2-bit internal system clock (FOSC), or 2 bits of the
prescaler, to create the 10-bit time base.
In PWM mode, CCPR1H is a read-only register.
DS41430A-page 114
 2010 Microchip Technology Inc.
PIC16F/LF720/721
15.3.2
PWM PERIOD
The PWM period is specified by the PR2 register of
Timer2. The PWM period can be calculated using the
formula of Equation 15-1.
EQUATION 15-1:
PWM PERIOD
PWM Period =   PR2  + 1   4  T OSC 
(TMR2 Prescale Value)
Note:
TOSC = 1/FOSC
When TMR2 is equal to PR2, the following three events
occur on the next increment cycle:
• TMR2 is cleared
• The CCP1 pin is set. (Exception: If the PWM duty
cycle = 0%, the pin will not be set.)
• The PWM duty cycle is latched from CCPR1L into
CCPR1H.
15.3.3
PWM DUTY CYCLE
The PWM duty cycle is specified by writing a 10-bit value
to multiple registers: CCPR1L register and DC1 and B1
bits of the CCP1CON register. The CCPR1L contains
the eight MSbs and the DC1 and B1 bits of the
CCP1CON register contain the two LSbs. CCPR1L and
DC1 and B1 bits of the CCP1CON register can be
written to at any time. The duty cycle value is not latched
into CCPR1H until after the period completes (i.e., a
match between PR2 and TMR2 registers occurs). While
using the PWM, the CCPR1H register is read-only.
Equation 15-2 is used to calculate the PWM pulse
width.
Equation 15-3 is used to calculate the PWM duty cycle
ratio.
EQUATION 15-2:
PULSE WIDTH
Pulse Width =  CCPR1L:CCP1CON<5:4>  
T OSC  (TMR2 Prescale Value)
Note:
The
Timer2
postscaler
(refer
to
Section 14.1 “Timer2 Operation”) is not
used in the determination of the PWM
frequency.
Note: TOSC = 1/FOSC
EQUATION 15-3:
DUTY CYCLE RATIO
 CCPR1L:CCP1CON<5:4> 
Duty Cycle Ratio = ----------------------------------------------------------------------4  PR2 + 1 
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.
The 8-bit timer TMR2 register is concatenated with
either the 2-bit internal system clock (FOSC), or 2 bits of
the prescaler, to create the 10-bit time base. The system
clock is used if the Timer2 prescaler is set to 1:1.
When the 10-bit time base matches the CCPR1H and
2-bit latch, then the CCP1 pin is cleared (refer to
Figure 15-3).
 2010 Microchip Technology Inc.
DS41430A-page 115
PIC16F/LF720/721
15.3.4
PWM RESOLUTION
EQUATION 15-4:
The resolution determines the number of available duty
cycles for a given period. For example, a 10-bit resolution
will result in 1024 discrete duty cycles, whereas an 8-bit
resolution will result in 256 discrete duty cycles.
log  4  PR2 + 1  
Resolution = ------------------------------------------ bits
log  2 
The maximum PWM resolution is 10 bits when PR2 is
255. The resolution is a function of the PR2 register
value as shown by Equation 15-4.
TABLE 15-4:
PR2 Value
4.88 kHz
19.53 kHz
78.12 kHz
156.3 kHz
208.3 kHz
16
4
1
1
1
1
0xFF
0xFF
0xFF
0x3F
0x1F
0x17
10
10
10
8
7
6.6
Maximum Resolution (bits)
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 8 MHz)
PWM Frequency
1.22 kHz
4.90 kHz
19.61 kHz
76.92 kHz
153.85 kHz
200.0 kHz
16
4
1
1
1
1
0x65
0x65
0x65
0x19
0x0C
0x09
8
8
8
6
5
5
Timer Prescale (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
OPERATION IN SLEEP MODE
In Sleep mode, the TMR2 register will not increment
and the state of the module will not change. If the CCP1
pin is driving a value, it will continue to drive that value.
When the device wakes up, TMR2 will continue from its
previous state.
15.3.6
CHANGES IN SYSTEM CLOCK
FREQUENCY
The PWM frequency is derived from the system clock
frequency (FOSC). Any changes in the system clock frequency will result in changes to the PWM frequency.
Refer to Section 7.0 “Oscillator Module” for
additional details.
15.3.8
1.
2.
3.
4.
5.
EFFECTS OF RESET
•
Any Reset will force all ports to Input mode and the
CCP registers to their Reset states.
•
6.
•
•
Disable the PWM pin (CCP1) output driver(s) by
setting the associated TRIS bit(s).
Load the PR2 register with the PWM period value.
Configure the CCP module for the PWM mode
by loading the CCP1CON register with the
appropriate values.
Load the CCPR1L register and the DCxBx bits of
the CCP1CON register, with the PWM duty cycle
value.
Configure and start Timer2:
Clear the TMR2IF interrupt flag bit of the PIR1
register. See Note below.
Configure the T2CKPS bits of the T2CON
register with the Timer2 prescale value.
Enable Timer2 by setting the TMR2ON bit of
the T2CON register.
Enable PWM output pin:
Wait until Timer2 overflows, TMR2IF bit of the
PIR1 register is set. See Note below.
Enable the PWM pin (CCP1) output driver(s)
by clearing the associated TRIS bit(s).
Note:
DS41430A-page 116
SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the CCP module for PWM operation:
•
15.3.7
If the pulse width value is greater than the
period the assigned PWM pin(s) will
remain unchanged.
1.22 kHz
Timer Prescale (1, 4, 16)
15.3.5
Note:
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 20 MHz)
PWM Frequency
TABLE 15-5:
PWM RESOLUTION
In order to send a complete duty cycle and
period on the first PWM output, the above
steps must be included in the setup
sequence. If it is not critical to start with a
complete PWM signal on the first output,
then step 6 may be ignored.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 15-6:
Name
SUMMARY OF REGISTERS ASSOCIATED WITH PWM
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
Bit 7
Bit 6
Bit 5
Bit 4
ANSELB
—
—
ANSB5
ANSB4
—
—
—
—
--11 ----
--11 ----
CCP1CON
—
—
DC1
B1
CCP1M3
CCP1M2
CCP1M1
CCP1M0
--00 0000
--00 0000
CCPR1L
Capture/Compare/PWM Register Low Byte
xxxx xxxx
uuuu uuuu
CCPR1H
Capture/Compare/PWM Register High Byte
xxxx xxxx
uuuu uuuu
Timer2 module Period Register
1111 1111
1111 1111
-000 0000
PR2
T2CON
—
TOUTPS3
TOUTPS2
TMR2
TRISB
TRISC
Legend:
TOUTPS1
TOUTPS0
TMR2ON
T2CKPS1
T2CKPS0
-000 0000
Timer2 module Register
0000 0000
0000 0000
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
1111 ----
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
- = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the PWM.
 2010 Microchip Technology Inc.
DS41430A-page 117
PIC16F/LF720/721
NOTES:
DS41430A-page 118
 2010 Microchip Technology Inc.
PIC16F/LF720/721
16.0
ADDRESSABLE UNIVERSAL
SYNCHRONOUS
ASYNCHRONOUS RECEIVER
TRANSMITTER (AUSART)
The AUSART module includes the following capabilities:
•
•
•
•
•
•
•
•
•
•
The
Addressable
Universal
Synchronous
Asynchronous Receiver Transmitter (AUSART)
module is a serial I/O communications peripheral. It
contains all the clock generators, shift registers and
data buffers necessary to perform an input or output
serial data transfer independent of device program
execution. The AUSART, also known as a Serial
Communications Interface (SCI), can be configured as
a full-duplex asynchronous system or half-duplex
synchronous system. Full-Duplex mode is useful for
communications with peripheral systems, such as CRT
terminals and personal computers. Half-Duplex
Synchronous mode is intended for communications
with peripheral devices, such as A/D or D/A integrated
circuits, serial EEPROMs or other microcontrollers.
These devices typically do not have internal clocks for
baud rate generation and require the external clock
signal provided by a master synchronous device.
FIGURE 16-1:
Full-duplex asynchronous transmit and receive
Two-character input buffer
One-character output buffer
Programmable 8-bit or 9-bit character length
Address detection in 9-bit mode
Input buffer overrun error detection
Received character framing error detection
Half-duplex synchronous master
Half-duplex synchronous slave
Sleep operation
Block diagrams of the AUSART transmitter and
receiver are shown in Figure 16-1 and Figure 16-2.
AUSART TRANSMIT BLOCK DIAGRAM
Data Bus
TXIE
Interrupt
TXIF
TXREG Register
8
TX/CK
MSb
LSb
(8)
0
Pin Buffer
and Control
TRMT
SPEN
• • •
Transmit Shift Register (TSR)
TXEN
Baud Rate Generator
FOSC
÷n
TX9
n
+1
SPBRG
Multiplier
x4
SYNC
1
0
0
BRGH
x
1
0
 2010 Microchip Technology Inc.
x16 x64
TX9D
DS41430A-page 119
PIC16F/LF720/721
FIGURE 16-2:
AUSART RECEIVE BLOCK DIAGRAM
SPEN
CREN
RX/DT
Baud Rate Generator
+1
SPBRG
RSR Register
MSb
Pin Buffer
and Control
Data
Recovery
FOSC
Multiplier
x4
x16 x64
SYNC
1
0
0
BRGH
x
1
0
Stop
OERR
(8)
•••
7
1
LSb
0 START
RX9
÷n
n
FERR
RX9D
RCREG Register
FIFO
8
Data Bus
RCIF
RCIE
Interrupt
The operation of the AUSART module is controlled
through two registers:
• Transmit Status and Control (TXSTA)
• Receive Status and Control (RCSTA)
These registers are detailed in Register 16-1 and
Register 16-2, respectively.
DS41430A-page 120
 2010 Microchip Technology Inc.
PIC16F/LF720/721
16.1
AUSART Asynchronous Mode
The AUSART transmits and receives data using the
standard non-return-to-zero (NRZ) format. NRZ is
implemented with two levels: a VOH mark state which
represents a ‘1’ data bit, and a VOL space state which
represents a ‘0’ data bit. NRZ refers to the fact that
consecutively transmitted data bits of the same value
stay at the output level of that bit without returning to a
neutral level between each bit transmission. An NRZ
transmission port idles in the mark state. Each character
transmission consists of one Start bit followed by eight
or nine data bits and is always terminated by one or
more Stop bits. The Start bit is always a space and the
Stop bits are always marks. The most common data
format is 8 bits. Each transmitted bit persists for a period
of 1/(baud rate). An on-chip dedicated 8-bit Baud Rate
Generator is used to derive standard baud rate
frequencies from the system oscillator. Refer to
Table 16-5 for examples of baud rate configurations.
The AUSART transmits and receives the LSb first. The
AUSART’s transmitter and receiver are functionally
independent, but share the same data format and baud
rate. Parity is not supported by the hardware, but can
be implemented in software and stored as the ninth
data bit.
16.1.1
AUSART ASYNCHRONOUS
TRANSMITTER
The AUSART transmitter block diagram is shown in
Figure 16-1. The heart of the transmitter is the serial
Transmit Shift Register (TSR), which is not directly
accessible by software. The TSR obtains its data from
the transmit buffer, which is the TXREG register.
16.1.1.1
Enabling the Transmitter
The AUSART transmitter is enabled for asynchronous
operations by configuring the following three control
bits:
• TXEN = 1
• SYNC = 0
• SPEN = 1
All other AUSART control bits are assumed to be in
their default state.
Setting the TXEN bit of the TXSTA register enables the
transmitter circuitry of the AUSART. Clearing the SYNC
bit of the TXSTA register configures the AUSART for
asynchronous operation. Setting the SPEN bit of the
RCSTA register enables the AUSART and automatically
configures the TX/CK I/O pin as an output.
 2010 Microchip Technology Inc.
Note 1: When the SPEN bit is set the RX/DT I/O
pin is automatically configured as an input,
regardless of the state of the corresponding TRIS bit and whether or not the AUSART receiver is enabled. The RX/DT pin
data can be read via a normal PORT read
but PORT latch data output is precluded.
2: The TXIF transmitter interrupt flag is set
when the TXEN enable bit is set.
16.1.1.2
Transmitting Data
A transmission is initiated by writing a character to the
TXREG register. If this is the first character, or the
previous character has been completely flushed from
the TSR, the data in the TXREG is immediately
transferred to the TSR register. If the TSR still contains
all or part of a previous character, the new character
data is held in the TXREG until the Stop bit of the
previous character has been transmitted. The pending
character in the TXREG is then transferred to the TSR
in one TCY immediately following the Stop bit
transmission. The transmission of the Start bit, data bits
and Stop bit sequence commences immediately
following the transfer of the data to the TSR from the
TXREG.
16.1.1.3
Transmit Interrupt Flag
The TXIF interrupt flag bit of the PIR1 register is set
whenever the AUSART transmitter is enabled and no
character is being held for transmission in the TXREG.
In other words, the TXIF bit is only clear when the TSR
is busy with a character and a new character has been
queued for transmission in the TXREG. The TXIF flag bit
is not cleared immediately upon writing TXREG. TXIF
becomes valid in the second instruction cycle following
the write execution. Polling TXIF immediately following
the TXREG write will return invalid results. The TXIF bit
is read-only, it cannot be set or cleared by software.
The TXIF interrupt can be enabled by setting the TXIE
interrupt enable bit of the PIE1 register. However, the
TXIF flag bit will be set whenever the TXREG is empty,
regardless of the state of TXIE enable bit.
To use interrupts when transmitting data, set the TXIE
bit only when there is more data to send. Clear the
TXIE interrupt enable bit upon writing the last character
of the transmission to the TXREG.
DS41430A-page 121
PIC16F/LF720/721
16.1.1.4
TSR Status
16.1.1.6
The TRMT bit of the TXSTA register indicates the
status of the TSR register. This is a read-only bit. The
TRMT bit is set when the TSR register is empty and is
cleared when a character is transferred to the TSR
register from the TXREG. The TRMT bit remains clear
until all bits have been shifted out of the TSR register.
No interrupt logic is tied to this bit, so the user has to
poll this bit to determine the TSR status.
Note:
16.1.1.5
1.
2.
3.
The TSR register is not mapped in data
memory, so it is not available to the user.
4.
Transmitting 9-Bit Characters
The AUSART supports 9-bit character transmissions.
When the TX9 bit of the TXSTA register is set, the
AUSART will shift 9 bits out for each character transmitted. The TX9D bit of the TXSTA register is the ninth,
and Most Significant, data bit. When transmitting 9-bit
data, the TX9D data bit must be written before writing
the 8 Least Significant bits into the TXREG. All nine bits
of data will be transferred to the TSR shift register
immediately after the TXREG is written.
5.
6.
7.
Asynchronous Transmission Setup:
Initialize the SPBRG register and the BRGH bit to
achieve the desired baud rate (Refer to
Section 16.2 “AUSART Baud Rate Generator
(BRG)”).
Enable the asynchronous serial port by clearing
the SYNC bit and setting the SPEN bit.
If 9-bit transmission is desired, set the TX9 control bit. A set ninth data bit will indicate that the 8
Least Significant data bits are an address when
the receiver is set for address detection.
Enable the transmission by setting the TXEN
control bit. This will cause the TXIF interrupt bit
to be set.
If interrupts are desired, set the TXIE interrupt
enable bit of the PIE1 register. An interrupt will
occur immediately provided that the GIE and
PEIE bits of the INTCON register are also set.
If 9-bit transmission is selected, the ninth bit
should be loaded into the TX9D data bit.
Load 8-bit data into the TXREG register. This
will start the transmission.
A special 9-bit Address mode is available for use with
multiple receivers. Refer to Section 16.1.2.7 “Address
Detection” for more information on the Address mode.
FIGURE 16-3:
ASYNCHRONOUS TRANSMISSION
Write to TXREG
BRG Output
(Shift Clock)
Word 1
TX/CK pin
Start bit
FIGURE 16-4:
bit 1
bit 7/8
Stop bit
Word 1
TXIF bit
(Transmit Buffer
Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
bit 0
1 TCY
Word 1
Transmit Shift Reg
ASYNCHRONOUS TRANSMISSION (BACK-TO-BACK)
Write to TXREG
BRG Output
(Shift Clock)
Word 1
TX/CK pin
TXIF bit
(Transmit Buffer
Empty Flag)
Word 2
Start bit
bit 0
1 TCY
bit 1
Word 1
bit 7/8
Stop bit
Start bit
bit 0
Word 2
1 TCY
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Note:
Word 1
Transmit Shift Reg.
Word 2
Transmit Shift Reg.
This timing diagram shows two consecutive transmissions.
DS41430A-page 122
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 16-1:
Name
REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
INTCON
RCSTA
SPBRG
BRG7
BRG6
BRG5
BRG4
BRG3
BRG2
BRG1
BRG0
0000 0000
0000 0000
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
0000 0000
0000 0000
0000 -010
0000 -010
TXREG
TXSTA
Legend:
16.1.2
AUSART Transmit Data Register
CSRC
TX9
TXEN
SYNC
—
BRGH
TRMT
TX9D
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for asynchronous transmission.
AUSART ASYNCHRONOUS
RECEIVER
The Asynchronous mode is typically used in RS-232
systems. The receiver block diagram is shown in
Figure 16-2. The data is received on the RX/DT pin and
drives the data recovery block. The data recovery block
is actually a high-speed shifter operating at 16 times
the baud rate, whereas the serial Receive Shift
Register (RSR) operates at the bit rate. When all 8 or 9
bits of the character have been shifted in, they are
immediately transferred to a two character First-In
First-Out (FIFO) memory. The FIFO buffering allows
reception of two complete characters and the start of a
third character before software must start servicing the
AUSART receiver. The FIFO and RSR registers are not
directly accessible by software. Access to the received
data is via the RCREG register.
16.1.2.1
The AUSART receiver is enabled for asynchronous
operation by configuring the following three control bits:
• CREN = 1
• SYNC = 0
• SPEN = 1
All other AUSART control bits are assumed to be in
their default state.
Setting the CREN bit of the RCSTA register enables the
receiver circuitry of the AUSART. Clearing the SYNC bit
of the TXSTA register configures the AUSART for
asynchronous operation. Setting the SPEN bit of the
RCSTA register enables the AUSART and automatically
configures the RX/DT I/O pin as an input.
Note:
 2010 Microchip Technology Inc.
Enabling the Receiver
When the SPEN bit is set, the TX/CK I/O
pin is automatically configured as an
output, regardless of the state of the
corresponding TRIS bit and whether or
not the AUSART transmitter is enabled.
The PORT latch is disconnected from the
output driver so it is not possible to use the
TX/CK pin as a general purpose output.
DS41430A-page 123
PIC16F/LF720/721
16.1.2.2
Receiving Data
The receiver data recovery circuit initiates character
reception on the falling edge of the first bit. The first bit,
also known as the Start bit, is always a zero. The data
recovery circuit counts one-half bit time to the center of
the Start bit and verifies that the bit is still a zero. If it is
not a zero then the data recovery circuit aborts
character reception, without generating an error, and
resumes looking for the falling edge of the Start bit. If
the Start bit zero verification succeeds then the data
recovery circuit counts a full bit time to the center of the
next bit. The bit is then sampled by a majority detect
circuit and the resulting ‘0’ or ‘1’ is shifted into the RSR.
This repeats until all data bits have been sampled and
shifted into the RSR. One final bit time is measured and
the level sampled. This is the Stop bit, which is always
a ‘1’. If the data recovery circuit samples a ‘0’ in the
Stop bit position then a framing error is set for this
character, otherwise the framing error is cleared for this
character. Refer to Section 16.1.2.4 “Receive
Framing Error” for more information on framing
errors.
Immediately after all data bits and the Stop bit have
been received, the character in the RSR is transferred
to the AUSART receive FIFO and the RCIF interrupt
flag bit of the PIR1 register is set. The top character in
the FIFO is transferred out of the FIFO by reading the
RCREG register.
Note:
16.1.2.3
If the receive FIFO is overrun, no additional
characters will be received until the overrun
condition
is
cleared.
Refer
to
Section 16.1.2.5 “Receive Overrun
Error” for more information on overrun
errors.
Receive Interrupts
The RCIF interrupt flag bit of the PIR1 register is set
whenever the AUSART receiver is enabled and there is
an unread character in the receive FIFO. The RCIF
interrupt flag bit is read-only, it cannot be set or cleared
by software.
RCIF interrupts are enabled by setting all of the
following bits:
• RCIE interrupt enable bit of the PIE1 register
• PEIE, Peripheral Interrupt Enable bit of the
INTCON register
• GIE, Global Interrupt Enable bit of the INTCON
register
16.1.2.4
Receive Framing Error
Each character in the receive FIFO buffer has a
corresponding framing error Status bit. A framing error
indicates that a Stop bit was not seen at the expected
time. The framing error status is accessed via the
FERR bit of the RCSTA register. The FERR bit
represents the status of the top unread character in the
receive FIFO. Therefore, the FERR bit must be read
before reading the RCREG.
The FERR bit is read-only and only applies to the top
unread character in the receive FIFO. A framing error
(FERR = 1) does not preclude reception of additional
characters. It is not necessary to clear the FERR bit.
Reading the next character from the FIFO buffer will
advance the FIFO to the next character and the next
corresponding framing error.
The FERR bit can be forced clear by clearing the SPEN
bit of the RCSTA register which resets the AUSART.
Clearing the CREN bit of the RCSTA register does not
affect the FERR bit. A framing error by itself does not
generate an interrupt.
Note:
16.1.2.5
If all receive characters in the receive
FIFO have framing errors, repeated reads
of the RCREG will not clear the FERR bit.
Receive Overrun Error
The receive FIFO buffer can hold two characters. An
overrun error will be generated if a third character, in its
entirety, is received before the FIFO is accessed. When
this happens the OERR bit of the RCSTA register is set.
The characters already in the FIFO buffer can be read
but no additional characters will be received until the
error is cleared. The error must be cleared by either
clearing the CREN bit of the RCSTA register or by
setting the AUSART by clearing the SPEN bit of the
RCSTA register.
16.1.2.6
Receiving 9-bit Characters
The AUSART supports 9-bit character reception. When
the RX9 bit of the RCSTA register is set, the AUSART
will shift 9 bits into the RSR for each character
received. The RX9D bit of the RCSTA register is the
ninth and Most Significant data bit of the top unread
character in the receive FIFO. When reading 9-bit data
from the receive FIFO buffer, the RX9D data bit must
be read before reading the 8 Least Significant bits from
the RCREG.
The RCIF interrupt flag bit of the PIR1 register will be
set when there is an unread character in the FIFO,
regardless of the state of interrupt enable bits.
DS41430A-page 124
 2010 Microchip Technology Inc.
PIC16F/LF720/721
16.1.2.7
Address Detection
A special Address Detection mode is available for use
when multiple receivers share the same transmission
line, such as in RS-485 systems. Address detection is
enabled by setting the ADDEN bit of the RCSTA
register.
Address detection requires 9-bit character reception.
When address detection is enabled, only characters
with the ninth data bit set will be transferred to the
receive FIFO buffer, thereby setting the RCIF interrupt
bit of the PIR1 register. All other characters will be
ignored.
Upon receiving an address character, user software
determines if the address matches its own. Upon
address match, user software must disable address
detection by clearing the ADDEN bit before the next
Stop bit occurs. When user software detects the end of
the message, determined by the message protocol
used, software places the receiver back into the
Address Detection mode by setting the ADDEN bit.
16.1.2.8
1.
2.
3.
4.
5.
6.
7.
8.
9.
Asynchronous Reception Setup:
Initialize the SPBRG register and the BRGH bit
to achieve the desired baud rate (refer to
Section 16.2 “AUSART Baud Rate Generator
(BRG)”).
Enable the serial port by setting the SPEN bit.
The SYNC bit must be clear for asynchronous
operation.
If interrupts are desired, set the RCIE bit of the
PIE1 register and the GIE and PEIE bits of the
INTCON register.
If 9-bit reception is desired, set the RX9 bit.
Enable reception by setting the CREN bit.
The RCIF interrupt flag bit of the PIR1 register
will be set when a character is transferred from
the RSR to the receive buffer. An interrupt will be
generated if the RCIE bit of the PIE1 register
was also set.
Read the RCSTA register to get the error flags
and, if 9-bit data reception is enabled, the ninth
data bit.
Get the received 8 Least Significant data bits
from the receive buffer by reading the RCREG
register.
If an overrun occurred, clear the OERR flag by
clearing the CREN receiver enable bit.
 2010 Microchip Technology Inc.
16.1.2.9
9-bit Address Detection Mode Setup
This mode would typically be used in RS-485 systems.
To set up an Asynchronous Reception with Address
Detect Enable:
1.
Initialize the SPBRG register and the BRGH bit
to achieve the desired baud rate (refer to
Section 16.2 “AUSART Baud Rate Generator
(BRG)”).
2. Enable the serial port by setting the SPEN bit.
The SYNC bit must be clear for asynchronous
operation.
3. If interrupts are desired, set the RCIE bit of the
PIE1 register and the GIE and PEIE bits of the
INTCON register.
4. Enable 9-bit reception by setting the RX9 bit.
5. Enable address detection by setting the ADDEN
bit.
6. Enable reception by setting the CREN bit.
7. The RCIF interrupt flag bit of the PIR1 register
will be set when a character with the ninth bit set
is transferred from the RSR to the receive buffer.
An interrupt will be generated if the RCIE interrupt enable bit of the PIE1 register was also set.
8. Read the RCSTA register to get the error flags.
The ninth data bit will always be set.
9. Get the received 8 Least Significant data bits
from the receive buffer by reading the RCREG
register. Software determines if this is the
device’s address.
10. If an overrun occurred, clear the OERR flag by
clearing the CREN receiver enable bit.
11. If the device has been addressed, clear the
ADDEN bit to allow all received data into the
receive buffer and generate interrupts.
DS41430A-page 125
PIC16F/LF720/721
FIGURE 16-5:
ASYNCHRONOUS RECEPTION
Start
bit
bit 0
RX/DT pin
bit 7/8 Stop
bit
bit 1
Rcv Shift
Reg
Rcv Buffer Reg
Start
bit
bit 0
bit 7/8 Stop
bit
Start
bit
bit 7/8 Stop
bit
Word 2
RCREG
Word 1
RCREG
Read Rcv
Buffer Reg
RCREG
RCIF
(Interrupt Flag)
OERR bit
CREN
Note:
This timing diagram shows three words appearing on the RX input. The RCREG (receive buffer) is read after the third word,
causing the OERR (overrun) bit to be set.
TABLE 16-2:
Name
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
INTCON
RCREG
AUSART Receive Data Register
0000 0000
0000 0000
0000 0000
0000 0000
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
SPBRG
BRG7
BRG6
BRG5
BRG4
BRG3
BRG2
BRG1
BRG0
0000 0000
0000 0000
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
TXSTA
CSRC
TX9
TXEN
SYNC
—
BRGH
TRMT
TX9D
0000 -010
0000 -010
Legend:
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for asynchronous reception.
DS41430A-page 126
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 16-1:
R/W-0
CSRC
TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
R/W-0
R/W-0
R/W-0
U-0
R/W-0
R-1
R/W-0
TX9
TXEN(1)
SYNC
—
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
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: AUSART mode Select bit
1 = Synchronous mode
0 = Asynchronous mode
bit 3
Unimplemented: Read as ‘0’
bit 2
BRGH: High Baud Rate Select bit
Asynchronous mode:
1 = High speed
0 = Low speed
Synchronous mode:
Unused in this mode
bit 1
TRMT: Transmit Shift Register Status bit
1 = TSR empty
0 = TSR full
bit 0
TX9D: Ninth bit of Transmit Data
Can be address/data bit or a parity bit.
Note 1:
x = Bit is unknown
SREN/CREN overrides TXEN in Synchronous mode.
 2010 Microchip Technology Inc.
DS41430A-page 127
PIC16F/LF720/721
REGISTER 16-2:
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)
1 = Serial port enabled (configures RX/DT and TX/CK pins as serial port pins)
0 = Serial port disabled (held in Reset)
bit 6
RX9: 9-bit Receive Enable bit
1 = Selects 9-bit reception
0 = Selects 8-bit reception
bit 5
SREN: Single Receive Enable bit
Asynchronous mode:
Don’t care
Synchronous mode – Master:
1 = Enables single receive
0 = Disables single receive
This bit is cleared after reception is complete.
Synchronous mode – Slave:
Don’t care
bit 4
CREN: Continuous Receive Enable bit
Asynchronous mode:
1 = Enables receiver
0 = Disables receiver
Synchronous mode:
1 = Enables continuous receive until enable bit CREN is cleared (CREN overrides SREN)
0 = Disables continuous receive
bit 3
ADDEN: Address Detect Enable bit
Asynchronous mode 9-bit (RX9 = 1):
1 = Enables address detection, enable interrupt and load the receive buffer when RSR<8> is set
0 = Disables address detection, all bytes are received and ninth bit can be used as parity bit
Asynchronous mode 8-bit (RX9 = 0):
Don’t care
Synchronous mode:
Must be set to ‘0’
bit 2
FERR: Framing Error bit
1 = Framing error (can be updated by reading RCREG register and receive next valid byte)
0 = No framing error
bit 1
OERR: Overrun Error bit
1 = Overrun error (can be cleared by clearing bit CREN)
0 = No overrun error
bit 0
RX9D: Ninth bit of Received Data
This can be address/data bit or a parity bit and must be calculated by user firmware.
Note 1: The AUSART module automatically changes the pin from tri-state to drive as needed. Configure
TRISx = 1.
DS41430A-page 128
 2010 Microchip Technology Inc.
PIC16F/LF720/721
16.2
EXAMPLE 16-1:
AUSART Baud Rate Generator
(BRG)
CALCULATING BAUD
RATE ERROR
For a device with FOSC of 16 MHz, desired baud rate of
9600, and Asynchronous mode with SYNC = 0 and BRGH
= 0 (as seen in Table 16-5):
The Baud Rate Generator (BRG) is an 8-bit timer that
is dedicated to the support of both the asynchronous
and synchronous AUSART operation.
F OS C
Desired Baud Rate = --------------------------------------64  SPBRG + 1 
The SPBRG register determines the period of the free
running baud rate timer. In Asynchronous mode the
multiplier of the baud rate period is determined by the
BRGH bit of the TXSTA register. In Synchronous mode,
the BRGH bit is ignored.
Solving for SPBRG:
F OS C
SPBRG =  --------------------------------------------------------- – 1
 64  Desired Baud Rate 
Table 16-3 contains the formulas for determining the
baud rate. Example 16-1 provides a sample calculation
for determining the baud rate and baud rate error.
16000000
=  ------------------------ – 1
 64  9600 
Typical baud rates and error values for various
asynchronous modes have been computed for your
convenience and are shown in Table 16-5. It may be
advantageous to use the high baud rate (BRGH = 1), to
reduce the baud rate error.
=  25.042  = 25
16000000
Actual Baud Rate = --------------------------64  25 + 1 
Writing a new value to the SPBRG register causes the
BRG timer to be reset (or cleared). This ensures that
the BRG does not wait for a timer overflow before
outputting the new baud rate.
= 9615
Actual Baud Rate – Desired Baud Rate
% Error =  -------------------------------------------------------------------------------------------------- 100


Desired Baud Rate
9615 – 9600
=  ------------------------------ 100 = 0.16%
 9600 
TABLE 16-3:
BAUD RATE FORMULAS
Configuration Bits
AUSART Mode
Baud Rate Formula
0
Asynchronous
FOSC/[64 (n+1)]
1
Asynchronous
FOSC/[16 (n+1)]
x
Synchronous
FOSC/[4 (n+1)]
SYNC
BRGH
0
0
1
Legend:
x = Don’t care, n = value of SPBRG register
TABLE 16-4:
Name
REGISTERS ASSOCIATED WITH THE BAUD RATE GENERATOR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
0000 000x
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
SPBRG
BRG7
BRG6
BRG5
BRG4
BRG3
BRG2
BRG1
BRG0
0000 0000
0000 0000
TXSTA
CSRC
TX9
TXEN
SYNC
—
BRGH
TRMT
TX9D
0000 -010
0000 -010
Legend:
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for the Baud Rate Generator.
 2010 Microchip Technology Inc.
DS41430A-page 129
PIC16F/LF720/721
TABLE 16-5:
BAUD RATES FOR ASYNCHRONOUS MODES
SYNC = 0, BRGH = 0
BAUD
RATE
FOSC = 20.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 18.432 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 16.0000 MHz
Actual
Rate
%
Error
FOSC = 11.0592 MHz
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
—
—
—
—
—
—
—
—
—
—
—
—
1200
1221
1.73
255
1200
0.00
239
1201
0.08
207
1200
0.00
143
2400
2404
0.16
129
2400
0.00
119
2403
0.16
103
2400
0.00
71
9600
9470
-1.36
32
9600
0.00
29
9615
0.16
25
9600
0.00
17
10417
10417
0.00
29
10286
-1.26
27
10416
-0.01
23
10165
-2.42
16
19.2k
19.53k
1.73
15
19.20k
0.00
14
19.23k
0.16
12
19.20k
0.00
8
57.6k
—
—
—
57.60k
0.00
7
—
—
—
57.60k
0.00
2
115.2k
—
—
—
—
—
—
—
—
—
—
—
—
SYNC = 0, BRGH = 0
BAUD
RATE
FOSC = 8.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 4.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 3.6864 MHz
Actual
Rate
FOSC = 1.000 MHz
%
Error
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
—
—
—
300
0.16
207
300
0.00
191
300
0.16
51
1200
1202
0.16
103
1202
0.16
51
1200
0.00
47
1202
0.16
12
2400
2404
0.16
51
2404
0.16
25
2400
0.00
23
—
—
—
9600
9615
0.16
12
—
—
—
9600
0.00
5
—
—
—
10417
10417
0.00
11
10417
0.00
5
—
—
—
—
—
—
19.2k
—
—
—
—
—
—
19.20k
0.00
2
—
—
—
57.6k
—
—
—
—
—
—
57.60k
0.00
0
—
—
—
115.2k
—
—
—
—
—
—
—
—
—
—
—
—
SYNC = 0, BRGH = 1
BAUD
RATE
FOSC = 20.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 18.432 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 16.0000 MHz
Actual
Rate
%
Error
FOSC = 11.0592 MHz
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
—
—
—
—
—
—
—
—
—
—
—
—
1200
—
—
—
—
—
—
—
—
—
—
—
—
2400
—
—
—
—
—
—
—
—
—
—
—
—
9600
9615
0.16
129
9600
0.00
119
9615
0.16
103
9600
0.00
71
10417
10417
0.00
119
10378
-0.37
110
10417
0.00
95
10473
0.53
65
19.2k
19.23k
0.16
64
19.20k
0.00
59
19.23k
0.16
51
19.20k
0.00
35
57.6k
56.82k
-1.36
21
57.60k
0.00
19
58.8k
2.12
16
57.60k
0.00
11
115.2k
113.64k
-1.36
10
115.2k
0.00
9
—
—
—
115.2k
0.00
5
DS41430A-page 130
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 16-5:
BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 1
BAUD
RATE
FOSC = 8.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 4.000 MHz
Actual
Rate
%
Error
SPBRG
value
(decimal)
FOSC = 3.6864 MHz
Actual
Rate
FOSC = 1.000 MHz
%
Error
SPBRG
value
(decimal)
Actual
Rate
%
Error
SPBRG
value
(decimal)
300
1200
—
—
—
—
—
—
—
1202
—
0.16
—
207
—
1200
—
0.00
—
191
300
1202
0.16
0.16
207
51
2400
2404
0.16
207
2404
0.16
103
2400
0.00
95
2404
0.16
25
—
9600
9615
0.16
51
9615
0.16
25
9600
0.00
23
—
—
10417
10417
0.00
47
10417
0.00
23
10473
0.53
21
10417
0.00
5
19.2k
19231
0.16
25
19.23k
0.16
12
19.2k
0.00
11
—
—
—
57.6k
55556
-3.55
8
—
—
—
57.60k
0.00
3
—
—
—
115.2k
—
—
—
—
—
—
115.2k
0.00
1
—
—
—
 2010 Microchip Technology Inc.
DS41430A-page 131
PIC16F/LF720/721
16.3
AUSART Synchronous Mode
Synchronous serial communications are typically used
in systems with a single master and one or more
slaves. The master device contains the necessary circuitry for baud rate generation and supplies the clock
for all devices in the system. Slave devices can take
advantage of the master clock by eliminating the
internal clock generation circuitry.
There are two signal lines in Synchronous mode: a
bidirectional data line and a clock line. Slaves use the
external clock supplied by the master to shift the serial
data into and out of their respective receive and transmit shift registers. Since the data line is bidirectional,
synchronous operation is half-duplex only. Half-duplex
refers to the fact that master and slave devices can
receive and transmit data but not both simultaneously.
The AUSART can operate as either a master or slave
device.
16.3.1.2
Data is transferred out of the device on the RX/DT pin.
The RX/DT and TX/CK pin output drivers are automatically enabled when the AUSART is configured for
synchronous master transmit operation.
A transmission is initiated by writing a character to the
TXREG register. If the TSR still contains all or part of a
previous character, the new character data is held in
the TXREG until the last bit of the previous character
has been transmitted. If this is the first character, or the
previous character has been completely flushed from
the TSR, the data in the TXREG is immediately transferred to the TSR. The transmission of the character
commences immediately following the transfer of the
data to the TSR from the TXREG.
Each data bit changes on the leading edge of the
master clock and remains valid until the subsequent
leading clock edge.
Start and Stop bits are not used in synchronous
transmissions.
16.3.1
SYNCHRONOUS MASTER MODE
The following bits are used to configure the AUSART
for Synchronous Master operation:
•
•
•
•
•
SYNC = 1
CSRC = 1
SREN = 0 (for transmit); SREN = 1 (for receive)
CREN = 0 (for transmit); CREN = 1 (for receive)
SPEN = 1
Setting the SYNC bit of the TXSTA register configures
the device for synchronous operation. Setting the CSRC
bit of the TXSTA register configures the device as a
master. Clearing the SREN and CREN bits of the RCSTA
register ensures that the device is in the Transmit mode,
otherwise the device will be configured to receive. Setting
the SPEN bit of the RCSTA register enables the
AUSART.
16.3.1.1
Master Clock
Synchronous data transfers use a separate clock line,
which is synchronous with the data. A device configured as a master transmits the clock on the TX/CK line.
The TX/CK pin output driver is automatically enabled
when the AUSART is configured for synchronous
transmit or receive operation. Serial data bits change
on the leading edge to ensure they are valid at the trailing edge of each clock. One clock cycle is generated
for each data bit. Only as many clock cycles are
generated as there are data bits.
DS41430A-page 132
Synchronous Master Transmission
Note:
The TSR register is not mapped in data
memory, so it is not available to the user.
16.3.1.3
Synchronous Master Transmission
Setup:
1.
2.
3.
4.
5.
6.
7.
8.
Initialize the SPBRG register and the BRGH bit
to achieve the desired baud rate (refer to
Section 16.2 “AUSART Baud Rate Generator
(BRG)”).
Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
Disable Receive mode by clearing bits SREN
and CREN.
Enable Transmit mode by setting the TXEN bit.
If 9-bit transmission is desired, set the TX9 bit.
If interrupts are desired, set the TXIE bit of the
PIE1 register and the GIE and PEIE bits of the
INTCON register.
If 9-bit transmission is selected, the ninth bit
should be loaded in the TX9D bit.
Start transmission by loading data to the TXREG
register.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 16-6:
SYNCHRONOUS TRANSMISSION
RX/DT
pin
bit 0
bit 1
Word 1
bit 2
bit 7
bit 0
bit 1
Word 2
bit 7
TX/CK pin
Write to
TXREG Reg
Write Word 1
Write Word 2
TXIF bit
(Interrupt Flag)
TRMT bit
TXEN bit
Note:
‘1’
‘1’
Synchronous Master mode, SPBRG = 0, continuous transmission of two 8-bit words.
FIGURE 16-7:
SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
RX/DT pin
bit 0
bit 2
bit 1
bit 6
bit 7
TX/CK pin
Write to
TXREG reg
TXIF bit
TRMT bit
TXEN bit
TABLE 16-6:
Name
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
INTCON
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
SPBRG
BRG7
BRG6
BRG5
BRG4
BRG3
BRG2
BRG1
BRG0
0000 0000
0000 0000
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
0000 0000
0000 0000
CSRC
TX9
TXEN
TRMT
TX9D
0000 -010
0000 -010
TXREG
TXSTA
Legend:
AUSART Transmit Data Register
SYNC
—
BRGH
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for synchronous master transmission.
 2010 Microchip Technology Inc.
DS41430A-page 133
PIC16F/LF720/721
16.3.1.4
Synchronous Master Reception
Data is received at the RX/DT pin. The RX/DT pin
output driver is automatically disabled when the
AUSART is configured for synchronous master receive
operation.
In Synchronous mode, reception is enabled by setting
either the Single Receive Enable bit (SREN of the
RCSTA register) or the Continuous Receive Enable bit
(CREN of the RCSTA register).
When SREN is set and CREN is clear, only as many
clock cycles are generated as there are data bits in a
single character. The SREN bit is automatically cleared
at the completion of one character. When CREN is set,
clocks are continuously generated until CREN is
cleared. If CREN is cleared in the middle of a character
the CK clock stops immediately and the partial character is discarded. If SREN and CREN are both set, then
SREN is cleared at the completion of the first character
and CREN takes precedence.
To initiate reception, set either SREN or CREN. Data is
sampled at the RX/DT pin on the trailing edge of the
TX/CK clock pin and is shifted into the Receive Shift
Register (RSR). When a complete character is
received into the RSR, the RCIF bit of the PIR1 register
is set and the character is automatically transferred to
the two character receive FIFO. The Least Significant
eight bits of the top character in the receive FIFO are
available in RCREG. The RCIF bit remains set as long
as there are un-read characters in the receive FIFO.
16.3.1.5
Slave Clock
Synchronous data transfers use a separate clock line,
which is synchronous with the data. A device configured
as a slave receives the clock on the TX/CK line. The TX/
CK pin output driver is automatically disabled when the
device is configured for synchronous slave transmit or
receive operation. Serial data bits change on the leading
edge to ensure they are valid at the trailing edge of each
clock. One data bit is transferred for each clock cycle.
Only as many clock cycles should be received as there
are data bits.
16.3.1.6
Receive Overrun Error
The receive FIFO buffer can hold two characters. An
overrun error will be generated if a third character, in its
entirety, is received before RCREG is read to access
the FIFO. When this happens the OERR bit of the
RCSTA register is set. Previous data in the FIFO will
not be overwritten. The two characters in the FIFO
buffer can be read, however, no additional characters
will be received until the error is cleared. The OERR bit
can only be cleared by clearing the overrun condition.
If the overrun error occurred when the SREN bit is set
and CREN is clear then the error is cleared by reading
RCREG. If the overrun occurred when the CREN bit is
set then the error condition is cleared by either clearing
the CREN bit of the RCSTA register.
DS41430A-page 134
16.3.1.7
Receiving 9-bit Characters
The AUSART supports 9-bit character reception. When
the RX9 bit of the RCSTA register is set, the AUSART
will shift 9-bits into the RSR for each character
received. The RX9D bit of the RCSTA register is the
ninth, and Most Significant, data bit of the top unread
character in the receive FIFO. When reading 9-bit data
from the receive FIFO buffer, the RX9D data bit must
be read before reading the 8 Least Significant bits from
the RCREG.
Address detection in Synchronous modes is not
supported, therefore the ADDEN bit of the RCSTA
register must be cleared.
16.3.1.8
Synchronous Master Reception
Setup
1.
Initialize the SPBRG register for the appropriate
baud rate. Set or clear the BRGH bit, as
required, to achieve the desired baud rate.
2. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
3. Ensure bits CREN and SREN are clear.
4. If interrupts are desired, set the RCIE bit of the
PIE1 register and the GIE and PEIE bits of the
INTCON register.
5. If 9-bit reception is desired, set bit RX9.
6. Verify address detection is disabled by clearing
the ADDEN bit of the RCSTA register.
7. Start reception by setting the SREN bit or for
continuous reception, set the CREN bit.
8. Interrupt flag bit RCIF of the PIR1 register will be
set when reception of a character is complete.
An interrupt will be generated if the RCIE interrupt enable bit of the PIE1 register was set.
9. Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during reception.
10. Read the 8-bit received data by reading the
RCREG register.
11. If an overrun error occurs, clear the error by
either clearing the CREN bit of the RCSTA
register or by clearing the SPEN bit, which
resets the AUSART.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 16-8:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
RX/DT
pin
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
TX/CK pin
Write to
bit SREN
SREN bit
CREN bit ‘0’
‘0’
RCIF bit
(Interrupt)
Read
RCREG
Note:
Timing diagram demonstrates Synchronous Master mode with bit SREN = 1 and bit BRGH = 0.
TABLE 16-7:
Name
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
all other
Resets
Value on
POR, BOR
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
0000 0000
0000 0000
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
TXSTA
CSRC
TX9
TXEN
SYNC
—
BRGH
TRMT
TX9D
0000 -010
0000 -010
INTCON
RCREG
Legend:
AUSART Receive Data Register
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for synchronous master reception.
 2010 Microchip Technology Inc.
DS41430A-page 135
PIC16F/LF720/721
16.3.2
SYNCHRONOUS SLAVE MODE
If two words are written to the TXREG and then the
SLEEP instruction is executed, the following will occur:
The following bits are used to configure the AUSART
for synchronous slave operation:
•
•
•
•
•
1.
SYNC = 1
CSRC = 0
SREN = 0 (for transmit); SREN = 1 (for receive)
CREN = 0 (for transmit); CREN = 1 (for receive)
SPEN = 1
2.
3.
4.
Setting the SYNC bit of the TXSTA register configures the
device for synchronous operation. Clearing the CSRC bit
of the TXSTA register configures the device as a slave.
Clearing the SREN and CREN bits of the RCSTA register
ensures that the device is in the Transmit mode,
otherwise the device will be configured to receive. Setting
the SPEN bit of the RCSTA register enables the
AUSART.
16.3.2.1
5.
16.3.2.2
1.
AUSART Synchronous Slave
Transmit
2.
3.
The operation of the Synchronous Master and Slave
modes are identical (refer to Section 16.3.1.2
“Synchronous Master Transmission”), except in the
case of the Sleep mode.
4.
5.
6.
7.
8.
TABLE 16-8:
The first character will immediately transfer to
the TSR register and transmit.
The second word will remain in TXREG register.
The TXIF bit will not be set.
After the first character has been shifted out of
TSR, the TXREG register will transfer the second
character to the TSR and the TXIF bit will now be
set.
If the PEIE and TXIE bits are set, the interrupt
will wake the device from Sleep and execute the
next instruction. If the GIE bit is also set, the
program will call the Interrupt Service Routine.
Synchronous Slave Transmission
Setup
Set the SYNC and SPEN bits and clear the
CSRC bit.
Clear the CREN and SREN bits.
If using interrupts, ensure that the GIE and PEIE
bits of the INTCON register are set and set the
TXIE bit.
If 9-bit transmission is desired, set the TX9 bit.
Enable transmission by setting the TXEN bit.
Verify address detection is disabled by clearing
the ADDEN bit of the RCSTA register.
If 9-bit transmission is selected, insert the Most
Significant bit into the TX9D bit.
Start transmission by writing the Least
Significant 8 bits to the TXREG register.
REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
INTCON
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
0000 0000
0000 0000
CSRC
TX9
TXEN
TRMT
TX9D
0000 -010
0000 -010
TXREG
TXSTA
Legend:
AUSART Transmit Data Register
SYNC
—
BRGH
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for synchronous slave transmission.
DS41430A-page 136
 2010 Microchip Technology Inc.
PIC16F/LF720/721
16.3.2.3
AUSART Synchronous Slave
Reception
16.3.2.4
1.
The operation of the Synchronous Master and Slave
modes is identical (Section 16.3.1.4 “Synchronous
Master Reception”), with the following exceptions:
2.
• Sleep
• CREN bit is always set, therefore the receiver is
never Idle
• SREN bit, which is a “don’t care” in Slave mode
3.
4.
5.
6.
A character may be received while in Sleep mode by
setting the CREN bit prior to entering Sleep. Once the
word is received, the RSR register will transfer the data
to the RCREG register. If the RCIE interrupt enable bit
of the PIE1 register is set, the interrupt generated will
wake the device from Sleep and execute the next
instruction. If the GIE bit is also set, the program will
branch to the interrupt vector.
7.
8.
9.
TABLE 16-9:
Synchronous Slave Reception Setup
Set the SYNC and SPEN bits and clear the
CSRC bit.
If interrupts are desired, set the RCIE bit of the
PIE1 register and the GIE and PEIE bits of the
INTCON register.
If 9-bit reception is desired, set the RX9 bit.
Verify address detection is disabled by clearing
the ADDEN bit of the RCSTA register.
Set the CREN bit to enable reception.
The RCIF bit of the PIR1 register will be set
when reception is complete. An interrupt will be
generated if the RCIE bit of the PIE1 register
was set.
If 9-bit mode is enabled, retrieve the Most
Significant bit from the RX9D bit of the RCSTA
register.
Retrieve the 8 Least Significant bits from the
receive FIFO by reading the RCREG register.
If an overrun error occurs, clear the error by
either clearing the CREN bit of the RCSTA
register.
REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
INTCON
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
0000 0000
0000 0000
RCREG
AUSART Receive Data Register
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
TXSTA
CSRC
TX9
TXEN
SYNC
—
BRGH
TRMT
TX9D
0000 -010
0000 -010
Legend:
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for synchronous slave reception.
 2010 Microchip Technology Inc.
DS41430A-page 137
PIC16F/LF720/721
16.4
AUSART Operation During Sleep
The AUSART will remain active during Sleep only in the
Synchronous Slave mode. All other modes require the
system clock and therefore cannot generate the
necessary signals to run the Transmit or Receive Shift
registers during Sleep.
Synchronous Slave mode uses an externally generated
clock to run the Transmit and Receive Shift registers.
16.4.1
SYNCHRONOUS RECEIVE DURING
SLEEP
To receive during Sleep, all the following conditions
must be met before entering Sleep mode:
• RCSTA and TXSTA Control registers must be
configured for synchronous slave reception (refer
to Section 16.3.2.4 “Synchronous Slave
Reception Setup”).
• If interrupts are desired, set the RCIE bit of the
PIE1 register and the PEIE bit of the INTCON
register.
• The RCIF interrupt flag must be cleared by
reading RCREG to unload any pending
characters in the receive buffer.
Upon entering Sleep mode, the device will be ready to
accept data and clocks on the RX/DT and TX/CK pins,
respectively. When the data word has been completely
clocked in by the external device, the RCIF interrupt
flag bit of the PIR1 register will be set. Thereby, waking
the processor from Sleep.
16.4.2
SYNCHRONOUS TRANSMIT
DURING SLEEP
To transmit during Sleep, all the following conditions
must be met before entering Sleep mode:
• RCSTA and TXSTA Control registers must be
configured for synchronous slave transmission
(refer to Section 16.3.2.2 “Synchronous Slave
Transmission Setup”).
• The TXIF interrupt flag must be cleared by writing
the output data to the TXREG, thereby filling the
TSR and transmit buffer.
• If interrupts are desired, set the TXIE bit of the
PIE1 register and the PEIE bit of the INTCON
register.
Upon entering Sleep mode, the device will be ready to
accept clocks on the TX/CK pin and transmit data on
the RX/DT pin. When the data word in the TSR has
been completely clocked out by the external device, the
pending byte in the TXREG will transfer to the TSR and
the TXIF flag will be set. Thereby, waking the processor
from Sleep. At this point, the TXREG is available to
accept another character for transmission, which will
clear the TXIF flag.
Upon waking from Sleep, the instruction following the
SLEEP instruction will be executed. If the GIE, Global
Interrupt Enable bit is also set then the Interrupt
Service Routine at address 0004h will be called.
Upon waking from Sleep, the instruction following the
SLEEP instruction will be executed. If the GIE, Global
Interrupt Enable bit of the INTCON register is also set,
then the Interrupt Service Routine at address 0004h
will be called.
DS41430A-page 138
 2010 Microchip Technology Inc.
PIC16F/LF720/721
17.0
SSP MODULE OVERVIEW
The Synchronous Serial Port (SSP) module is a serial
interface useful for communicating with other peripherals or microcontroller devices. These peripheral
devices may be serial EEPROMs, shift registers, display drivers, A/D converters, etc. The SSP module can
operate in one of two modes:
• Serial Peripheral Interface (SPI)
• Inter-Integrated Circuit (I2C™)
17.1
A typical SPI connection between microcontroller
devices is shown in Figure 17-1. Addressing of more
than one slave device is accomplished via multiple
hardware slave select lines. External hardware and
additional I/O pins must be used to support multiple
slave select addressing. This prevents extra overhead
in software for communication.
For SPI communication, typically three pins are used:
• Serial Data Out (SDO)
• Serial Data In (SDI)
• Serial Clock (SCK)
SPI Mode
The SPI mode allows 8 bits of data to be synchronously
transmitted and received, simultaneously. The SSP
module can be operated in one of two SPI modes:
Additionally, a fourth pin may be used when in a Slave
mode of operation:
• Slave Select (SS)
• Master mode
• Slave mode
SPI is a full-duplex protocol, with all communication
being bidirectional and initiated by a master device. All
clocking is provided by the master device and all bits
are transmitted, MSb first. Care must be taken to
ensure that all devices on the SPI bus are setup to
allow all controllers to send and receive data at the
same time.
FIGURE 17-1:
TYPICAL SPI MASTER/SLAVE CONNECTION
SPI Master SSPM<3:0> = 00xx
SPI Slave SSPM<3:0> = 010x
SDO
SDI
Serial Input Buffer
(SSPBUF)
SDI
Shift Register
(SSPSR)
MSb
Serial Input Buffer
(SSPBUF)
LSb
General I/O
 2010 Microchip Technology Inc.
Shift Register
(SSPSR)
MSb
SCK
Processor 1
SDO
Serial Clock
Slave Select
(optional)
LSb
SCK
SS
Processor 2
DS41430A-page 139
PIC16F/LF720/721
FIGURE 17-2:
SPI MODE BLOCK
DIAGRAM
Internal
Data Bus
Read
Write
SSPBUF Reg
SSPSR Reg
SDI
bit 0
Shift
Clock
bit 7
SDO
SS
Control
Enable
RA5/SS
RA0/SS
SSSEL
2
Clock Select
Edge
Select
2
Edge
Select
Prescaler
4, 16, 64
SCK
TRISx
TMR2
Output
FOSC
4
SSPM<3:0>
DS41430A-page 140
 2010 Microchip Technology Inc.
PIC16F/LF720/721
17.1.1
MASTER MODE
In Master mode, data transfer can be initiated at any
time because the master controls the SCK line. Master
mode determines when the slave (Figure 17-1,
Processor 2) transmits data via control of the SCK line.
17.1.1.1
Master Mode Operation
The SSP consists of a transmit/receive shift register
(SSPSR) and a buffer register (SSPBUF). The SSPSR
register shifts the data in and out of the device, MSb
first. The SSPBUF register holds the data that is written
out of the master until the received data is ready. Once
the eight bits of data have been received, the byte is
moved to the SSPBUF register. The Buffer Full Status
bit, BF of the SSPSTAT register, and the SSP Interrupt
Flag bit, SSPIF of the PIR1 register, are then set.
Any write to the SSPBUF register during transmission/
reception of data will be ignored and the Write Collision
Detect bit, WCOL of the SSPCON register, will be set.
User software must clear the WCOL bit so that it can be
determined if the following write(s) to the SSPBUF
register completed successfully.
When the application software is expecting to receive
valid data, the SSPBUF should be read before the next
byte of data is written to the SSPBUF. The BF bit of the
SSPSTAT register is set 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. The SSP interrupt may be used to
determine when the transmission/reception is
complete and the SSPBUF must be read and/or
written. If interrupts are not 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.
Note:
17.1.1.2
The SSPSR is not directly readable or
writable and can only be accessed by
addressing the SSPBUF register.
Enabling Master I/O
To enable the serial port, the SSPEN bit of the
SSPCON register, must be set. To reset or reconfigure
SPI mode, clear the SSPEN bit, re-initialize the
SSPCON register and then set the SSPEN bit. If a
Master mode of operation is selected in the SSPM bits
of the SSPCON register, the SDI, SDO and SCK pins
will be assigned as serial port pins.
17.1.1.3
Master Mode Setup
In Master mode, the data is transmitted/received as
soon as the SSPBUF register is loaded with a byte
value. If the master is only going to receive, SDO output
could be disabled (programmed and used as an input).
The SSPSR register will continue to shift in the signal
present on the SDI pin at the programmed clock rate.
When initializing SPI Master mode operation, several
options need to be specified. This is accomplished by
programming the appropriate control bits in the
SSPCON and SSPSTAT registers. These control bits
allow the following to be specified:
•
•
•
•
•
SCK as clock output
Idle state of SCK (CKP bit)
Data input sample phase (SMP bit)
Output data on rising/falling edge of SCK (CKE bit)
Clock bit rate
In Master mode, the SPI clock rate (bit rate) is user
selectable 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 of 5 Mbps
(at FOSC = 16 MHz).
Figure 17-3 shows the waveforms for Master mode.
The clock polarity is selected by appropriately programming the CKP bit of the SSPCON register. When the
CKE bit is set, the SDO data is valid before there is a
clock edge on SCK. The sample time of the input data
is shown based on the state of the SMP bit and can
occur at the middle or end of the data output time. The
time when the SSPBUF is loaded with the received
data is shown.
17.1.1.4
Sleep in Master Mode
In Master mode, all module clocks are halted and the
transmission/reception will remain in their current state,
paused, until the device wakes from Sleep. After the
device wakes up from Sleep, the module will continue
to transmit/receive data.
For these pins to function as serial port pins, they must
have their corresponding data direction bits set or
cleared in the associated TRIS register as follows:
• SDI configured as input
• SDO configured as output
• SCK configured as output
 2010 Microchip Technology Inc.
DS41430A-page 141
PIC16F/LF720/721
FIGURE 17-3:
SPI MASTER MODE WAVEFORM
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 0
bit 7
Input
Sample
(SMP = 1)
SSPIF
SSPSR to
SSPBUF
EXAMPLE 17-1:
LOOP
BANKSEL
BTFSS
GOTO
BANKSEL
MOVF
MOVWF
MOVF
MOVWF
DS41430A-page 142
LOADING THE SSPBUF (SSPSR) REGISTER
SSPSTAT
SSPSTAT, BF
LOOP
SSPBUF
SSPBUF, W
RXDATA
TXDATA, W
SSPBUF
;
;Has data been received(transmit complete)?
;No
;
;WREG reg = contents of SSPBUF
;Save in user RAM, if data is meaningful
;W reg = contents of TXDATA
;New data to xmit
 2010 Microchip Technology Inc.
PIC16F/LF720/721
17.1.2
SLAVE MODE
For any SPI device acting as a slave, the data is
transmitted and received as external clock pulses
appear on SCK pin. This external clock must meet the
minimum high and low times as specified in the
electrical specifications.
17.1.2.1
Slave Mode Operation
The SSP 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.
The slave has no control as to when data will be
clocked in or out of the device. All data that is to be
transmitted, to a master or another slave, must be
loaded into the SSPBUF register before the first clock
pulse is received.
Once eight bits of data have been received:
• Received byte is moved to the SSPBUF register
• BF bit of the SSPSTAT register is set
• SSPIF bit of the PIR1 register is set
Any write to the SSPBUF register during transmission/
reception of data will be ignored and the Write Collision
Detect bit, WCOL of the SSPCON register, will be set.
User software must clear the WCOL bit so that it can be
determined if the following write(s) to the SSPBUF
register completed successfully.
The user’s firmware must read SSPBUF, clearing the
BF flag, or the SSPOV bit of the SSPCON register will
be set with the reception of the next byte and
communication will be disabled.
A SPI module transmits and receives at the same time,
occasionally causing dummy data to be transmitted/
received. It is up to the user to determine which data is
to be used and what can be discarded.
 2010 Microchip Technology Inc.
17.1.2.2
Enabling Slave I/O
To enable the serial port, the SSPEN bit of the
SSPCON register must be set. If a Slave mode of
operation is selected in the SSPM bits of the SSPCON
register, the SDI, SDO and SCK pins will be assigned
as serial port pins.
For these pins to function as serial port pins, they must
have their corresponding data direction bits set or
cleared in the associated TRIS register as follows:
• SDI configured as input
• SDO configured as output
• SCK configured as input
Optionally, a fourth pin, Slave Select (SS) may be used
in Slave mode. Slave Select may be configured to
operate on the RC6/SS pin via the SSSEL bit in the
APFCON register.
Upon selection of a Slave Select pin, the appropriate
bits must be set in the ANSELA and TRISA registers.
Slave Select must be set as an input by setting the
corresponding bit in TRISA, and digital I/O must be
enabled on the SS pin by clearing the corresponding bit
of the ANSELA register.
17.1.2.3
Slave Mode Setup
When initializing the SSP module to SPI Slave mode,
compatibility must be ensured with the master device.
This is done by programming the appropriate control
bits of the SSPCON and SSPSTAT registers. These
control bits allow the following to be specified:
•
•
•
•
SCK as clock input
Idle state of SCK (CKP bit)
Data input sample phase (SMP bit)
Output data on rising/falling edge of SCK (CKE bit)
Figure 17-4 and Figure 17-5 show example waveforms
of Slave mode operation.
DS41430A-page 143
PIC16F/LF720/721
FIGURE 17-4:
SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 0)
SS
Optional
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
Write to
SSPBUF
SDO
bit 7
SDI
(SMP = 0)
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
SSPSR to
SSPBUF
FIGURE 17-5:
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
SDI
(SMP = 0)
bit 6
bit 7
bit 7
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
bit 0
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
SSPSR to
SSPBUF
DS41430A-page 144
 2010 Microchip Technology Inc.
PIC16F/LF720/721
17.1.2.4
Slave Select Operation
The SS pin allows Synchronous Slave mode operation.
The SPI must be in Slave mode with SS pin control
enabled (SSPM<3:0> = 0100). The associated TRIS bit
for the SS pin must be set, making SS an input.
Note:
In Slave Select mode, when:
• SS = 0, The device operates as specified in
Section 17.1.2 “Slave Mode”.
• SS = 1, The SPI module is held in Reset and the
SDO pin will be tri-stated.
Note 1: When the SPI is in Slave mode with SS
pin control enabled (SSPM<3:0> = 0100),
the SPI module will reset if the SS pin is
driven high.
2: If the SPI is used in Slave mode with CKE
set, the SS pin control must be enabled.
FIGURE 17-6:
When the SPI module resets, the bit counter is cleared
to ‘0’. This can be done by either forcing the SS pin to
a high level or clearing the SSPEN bit. Figure 17-6
shows the timing waveform for such a synchronization
event.
17.1.2.5
SSPSR must be reinitialized by writing to
the SSPBUF register before the data can
be clocked out of the slave again.
Sleep in Slave Mode
While in Sleep mode, the slave can transmit/receive
data. The SPI Transmit/Receive Shift register operates
asynchronously to the device on the externally supplied
clock source. This allows the device to be placed in
Sleep mode and data to be shifted into the SPI Transmit/Receive Shift register. When all 8 bits have been
received, the SSP Interrupt Flag bit will be set and, if
enabled, will wake the device from Sleep.
SLAVE SELECT SYNCHRONIZATION WAVEFORM
SS
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
Write to
SSPBUF
SDO
SDI
(SMP = 0)
SSPSR must be reinitialized by writing to
the SSPBUF register before the data can
be clocked out of the slave again.
bit 7
bit 6
bit 7
bit 0
bit 0
bit 7
bit 7
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
SSPSR to
SSPBUF
 2010 Microchip Technology Inc.
DS41430A-page 145
PIC16F/LF720/721
REGISTER 17-1:
SSPCON: SYNC SERIAL PORT CONTROL REGISTER (SPI MODE)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
WCOL: Write Collision Detect bit
1 = The SSPBUF 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 = 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. In Master mode the overflow
bit is not set since each new reception (and transmission) is initiated by writing to the SSPBUF
register.
0 = No overflow
bit 5
SSPEN: Synchronous Serial Port Enable bit
1 = Enables serial port and configures SCK, SDO and SDI as serial port pins(1)
0 = Disables serial port and configures these pins as I/O port pins
bit 4
CKP: Clock Polarity Select bit
1 = Idle state for clock is a high level
0 = Idle state for clock is a low level
bit 3-0
SSPM<3:0>: Synchronous Serial Port mode Select bits
0000 = SPI Master mode, clock = FOSC/4
0001 = SPI Master mode, clock = FOSC/16
0010 = SPI Master mode, clock = FOSC/64
0011 = SPI Master mode, clock = TMR2 output/2
0100 = SPI Slave mode, clock = SCK pin. SS pin control enabled.
0101 = SPI Slave mode, clock = SCK pin. SS pin control disabled. SS can be used as I/O pin.
Note 1:
When enabled, these pins must be properly configured as input or output.
DS41430A-page 146
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 17-2:
SSPSTAT: SYNC SERIAL PORT STATUS REGISTER (SPI MODE)
R/W-0
R/W-0
R-0
R-0
R-0
R-0
R-0
R-0
SMP
CKE
D/A
P
S
R/W
UA
BF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7
SMP: SPI Data Input Sample Phase 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 Edge Select bit
SPI mode, CKP = 0:
1 = Data stable on rising edge of SCK
0 = Data stable on falling edge of SCK
SPI mode, CKP = 1:
1 = Data stable on falling edge of SCK
0 = Data stable on rising edge of SCK
bit 5
D/A: Data/Address bit
Used in I2C mode only.
bit 4
P: Stop bit
Used in I2C mode only.
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
1 = Receive complete, SSPBUF is full
0 = Receive not complete, SSPBUF is empty
 2010 Microchip Technology Inc.
x = Bit is unknown
DS41430A-page 147
PIC16F/LF720/721
TABLE 17-1:
Name
SUMMARY OF REGISTERS ASSOCIATED WITH SPI OPERATION
Bit 7
Bit 6
ANSELC
ANSC7
ANSC6
INTCON
GIE
PEIE
TMR1GIE
ADIE
RCIE
PIE1
PIR1
TMR1GIF
Bit 5
Bit 3
—
—
TMR0IE
INTE
TXIE
Value on all
other Resets
Bit 1
Bit 0
ANSC3
ANSC2
ANSC1
ANSC0
11-- 1111
11-- 1111
RABIE
TMR0IF
INTF
RABIF
0000 000x
0000 000x
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
TMR1IF
0000 0000
0000 0000
Timer2 module Period Register
1111 1111
1111 1111
Synchronous Serial Port Receive Buffer/Transmit Register
xxxx xxxx
uuuu uuuu
RCIF
PR2
SSPBUF
Value on
POR, BOR
Bit 2
ADIF
Bit 4
TXIF
SSPIF
CCP1IF
TMR2IF
SSPCON
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
0000 0000
0000 0000
SSPSTAT
SMP
CKE
D/A
P
S
R/W
UA
BF
0000 0000
0000 0000
TRISB
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
1111 ----
TRISC
TRISC7
TRISC6
TRISC5
TRISC4
TRISC3
TRISC2
TRISC1
TRISC0
1111 1111
1111 1111
—
TOUTPS3
TOUTPS2
TOUTPS1
TOUTPS0
TMR2ON
T2CKPS1
T2CKPS0
-000 0000
-000 0000
T2CON
Legend:
x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the SSP in SPI mode.
DS41430A-page 148
 2010 Microchip Technology Inc.
PIC16F/LF720/721
I2C Mode
17.2
FIGURE 17-8:
The SSP module, in I2C mode, implements all slave
functions except general call support. It provides
interrupts on Start and Stop bits in hardware to facilitate
firmware implementations of the master functions. The
SSP module implements the I2C Standard mode
specifications:
VDD
Data is sampled on the rising edge and shifted out on
the falling edge of the clock. This ensures that the SDA
signal is valid during the SCL high time. The SCL clock
input must have minimum high and low times for proper
operation. Refer to Section 23.0 “Electrical
Specifications”.
I2C™ MODE BLOCK
DIAGRAM
FIGURE 17-7:
Internal
Data Bus
Read
Write
SSPBUF Reg
SCL
Shift
Clock
Slave 1
SDA
SDA
SCL
SCL
Slave 2
SDA
SCL
(optional)
The SSP module has six registers for I2C operation.
They are:
•
•
•
•
SSP Control (SSPCON) register
SSP Status (SSPSTAT) register
Serial Receive/Transmit Buffer (SSPBUF) register
SSP Shift Register (SSPSR), not directly
accessible
• SSP Address (SSPADD) register
• SSP Address Mask (SSPMSK) register
17.2.1
HARDWARE SETUP
Selection of I2C mode, with the SSPEN bit of the
SSPCON register set, forces the SCL and SDA pins to
be open drain, provided these pins are programmed as
inputs by setting the appropriate TRISC bits. The SSP
module will override the input state with the output data,
when required, such as for Acknowledge and slavetransmitter sequences.
Note:
SSPSR Reg
SDA
VDD
Master
I2C Slave mode (7-bit address)
I2C Slave mode (10-bit address)
Start and Stop bit interrupts enabled to support
firmware Master mode
• Address masking
•
•
•
Two pins are used for data transfer; the SCL pin (clock
line) and the SDA pin (data line). The user must
configure the two pin’s data direction bits as inputs in
the appropriate TRIS register. Upon enabling I2C
mode, the I2C slew rate limiters in the I/O pads are
controlled by the SMP bit of SSPSTAT register. The
SSP module functions are enabled by setting the
SSPEN bit of SSPCON register.
TYPICAL I2C™
CONNECTIONS
Pull-up resistors must be provided
externally to the SCL and SDA pins for
proper operation of the I2C module.
LSb
MSb
SSPMSK Reg
Match Detect
Addr Match
SSPADD Reg
Start and
Stop bit Detect
 2010 Microchip Technology Inc.
DS41430A-page 149
PIC16F/LF720/721
17.2.2
START AND STOP CONDITIONS
During times of no data transfer (Idle time), both the
clock line (SCL) and the data line (SDA) are pulled high
through external pull-up resistors. The Start and Stop
conditions determine the start and stop of data transmission. The Start condition is defined as a high-to-low
transition of the SDA line while SCL is high. The Stop
condition is defined as a low-to-high transition of the
SDA line while SCL is high.
FIGURE 17-9:
Figure 17-9 shows the Start and Stop conditions. A
master device generates these conditions for starting
and terminating data transfer. Due to the definition of
the Start and Stop conditions, when data is being transmitted, the SDA line can only change state when the
SCL line is low.
START AND STOP CONDITIONS
SDA
SCL
S
Start
P
Change of
Change of
Data Allowed
Data Allowed
Condition
17.2.3
Stop
Condition
ACKNOWLEDGE
After the valid reception of an address or data byte, the
hardware automatically will generate the Acknowledge
(ACK) pulse and load the SSPBUF register with the
received value currently in the SSPSR register. There
are certain conditions that will cause the SSP module
not to generate this ACK pulse. They include any or all
of the following:
In such a case, the SSPSR register value is not loaded
into the SSPBUF, but bit SSPIF of the PIR1 register is
set. Table 17-2 shows the results of when a data
transfer byte is received, given the status of bits BF and
SSPOV. Flag bit BF is cleared by reading the SSPBUF
register, while bit SSPOV is cleared through software.
• The Buffer Full bit, BF of the SSPSTAT register,
was set before the transfer was received.
• The SSP Overflow bit, SSPOV of the SSPCON
register, was set before the transfer was received.
• The SSP module is being operated in Firmware
Master mode.
TABLE 17-2:
DATA TRANSFER RECEIVED BYTE ACTIONS
Status Bits as Data
Transfer is Received
SSPSR  SSPBUF
Generate ACK
Pulse
Set bit SSPIF
(SSP Interrupt occurs
if enabled)
BF
SSPOV
0
0
Yes
Yes
Yes
1
0
No
No
Yes
1
1
No
No
Yes
0
1
No
No
Yes
Note 1:
Shaded cells show the conditions where the user software did not properly clear the overflow condition.
DS41430A-page 150
 2010 Microchip Technology Inc.
PIC16F/LF720/721
17.2.4
ADDRESSING
Once the SSP 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
line (SCL).
17.2.4.1
7-bit Addressing
In 7-bit Addressing mode (Figure 17-10), the value of
register SSPSR<7:1> is compared to the value of register SSPADD<7:1>. 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:
• The SSPSR register value is loaded into the
SSPBUF register.
• The BF bit is set.
• An ACK pulse is generated.
• SSP Interrupt Flag bit, SSPIF of the PIR1 register,
is set (interrupt is generated if enabled) on the
falling edge of the ninth SCL pulse.
17.2.4.2
10-bit Addressing
In 10-bit Address mode, two address bytes need to be
received by the slave (Figure 17-11). The five Most
Significant bits (MSbs) of the first address byte specify
if it is a 10-bit address. The R/W bit of the SSPSTAT
register must specify a write so the slave device will
receive the second address byte. For a 10-bit address,
the first byte would equal ‘1111 0 A9 A8 0’, where
A9 and A8 are the two MSbs of the address.
The sequence of events for 10-bit address is as follows
for reception:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Load SSPADD register with high byte of address.
Receive first (high) byte of address (bits SSPIF,
BF and UA of the SSPSTAT register are set).
Read the SSPBUF register (clears bit BF).
Clear the SSPIF flag bit.
Update the SSPADD register with second (low)
byte of address (clears UA bit and releases the
SCL line).
Receive low byte of address (bits SSPIF, BF and
UA are set).
Update the SSPADD register with the high byte
of address. If match releases SCL line, this will
clear bit UA.
Read the SSPBUF register (clears bit BF).
Clear flag bit SSPIF.
If data is requested by the master, once the slave has
been addressed:
1.
2.
3.
4.
5.
Receive repeated Start condition.
Receive repeat of high byte address with R/W = 1,
indicating a read.
BF bit is set and the CKP bit is cleared, stopping
SCL and indicating a read request.
SSPBUF is written, setting BF, with the data to
send to the master device.
CKP is set in software, releasing the SCL line.
17.2.4.3
Address Masking
The Address Masking register (SSPMSK) is only
accessible while the SSPM bits of the SSPCON
register are set to ‘1001’. In this register, the user can
select which bits of a received address the hardware
will compare when determining an address match. Any
bit that is set to a zero in the SSPMSK register, the
corresponding bit in the received address byte and
SSPADD register are ignored when determining an
address match. By default, the register is set to all
ones, requiring a complete match of a 7-bit address or
the lower eight bits of a 10-bit address.
 2010 Microchip Technology Inc.
DS41430A-page 151
PIC16F/LF720/721
17.2.5
RECEPTION
When the R/W bit of the received address byte is clear,
the master will write data to the slave. If an address
match occurs, the received address is loaded into the
SSPBUF register. An address byte overflow will occur
if that loaded address is not read from the SSPBUF
before the next complete byte is received.
An SSP interrupt is generated for each data transfer byte.
The BF, R/W and D/A bits of the SSPSTAT register are
used to determine the status of the last received byte.
I2C™ WAVEFORMS FOR RECEPTION (7-BIT ADDRESS)
FIGURE 17-10:
R/W = 0
Receiving Address
SCL
S
1
2
SSPIF
BF
3
4
5
6
Receiving Data
ACK
A7 A6 A5 A4 A3 A2 A1
SDA
7
ACK
D7 D6 D5 D4 D3 D2 D1 D0
8
9
1
2
3
4
5
6
7
8
9
Receiving Data
ACK
D7 D6 D5 D4 D3 D2 D1 D0
1
2
3
4
5
6
7
8
Cleared in software
9
P
Bus Master
sends Stop
condition
SSPBUF register is read
SSPOV
Bit SSPOV is set because the SSPBUF register is still full.
ACK is not sent.
DS41430A-page 152
 2010 Microchip Technology Inc.
 2010 Microchip Technology Inc.
CKP
UA
SSPOV
BF
SSPIF
1
SCL
S
1
3
1
4
1
5
0
6
A9
7
8
UA is set indicating
that the SSPADD needs to
be updated
SSPBUF is written
with contents of SSPSR
Cleared in software
2
1
9
R/W ACK
A8
0
2
A6
4
A4
5
A3
6
A2
Cleared in software
3
A5
7
A1
UA is set indicating
that SSPADD needs to
be updated
Cleared by hardware
when SSPADD is updated
with low byte of address
Dummy read of SSPBUF
to clear BF flag
1
A7
Receive Second Byte of Address
8
A0
9
ACK
1
D7
4
5
6
7
8
D2 D1 D0
Cleared in software
3
D3
Receive Data Byte
D5 D4
Cleared by hardware when
SSPADD is updated with high
byte of address
2
D6
Clock is held low until
update of SSPADD has
taken place
9
ACK
1
2
D7 D6
4
5
6
D3 D2
Cleared in software
3
D5 D4
Receive Data Byte
7
8
D1 D0
P
Bus master
sends Stop
condition
SSPOV is set
because SSPBUF is
still full. ACK is not sent.
9
ACK
FIGURE 17-11:
SDA
Receive First Byte of Address
Clock is held low until
update of SSPADD has
taken place
PIC16F/LF720/721
I2C™ SLAVE MODE TIMING (RECEPTION, 10-BIT ADDRESS)
DS41430A-page 153
PIC16F/LF720/721
17.2.6
TRANSMISSION
When the R/W bit of the received address byte is set
and an address match occurs, the R/W bit of the
SSPSTAT register is set and the slave will respond to
the master by reading out data. After the address match,
an ACK pulse is generated by the slave hardware and
the SCL pin is held low (clock is automatically stretched)
until the slave is ready to respond. See Section 17.2.7
“Clock Stretching”. The data the slave will transmit
must be loaded into the SSPBUF register, which sets
the BF bit. The SCL line is released by setting the CKP
bit of the SSPCON register.
Following the 8th falling clock edge, control of the SDA
line is released back to the master so that the master
can acknowledge or not acknowledge the response. If
the master sends a not acknowledge, the slave’s
transmission is complete and the slave must monitor for
the next Start condition. If the master acknowledges,
control of the bus is returned to the slave to transmit
another byte of data. Just as with the previous byte, the
clock is stretched by the slave, data must be loaded into
the SSPBUF and CKP must be set to release the clock
line (SCL).
An SSP interrupt is generated for each transferred data
byte. The SSPIF flag bit of the PIR1 register initiates an
SSP interrupt, and must be cleared by software before
the next byte is transmitted. The BF bit of the SSPSTAT
register is cleared on the falling edge of the 8th
received clock pulse. The SSPIF flag bit is set on the
falling edge of the ninth clock pulse.
FIGURE 17-12:
I 2C WAVEFORMS FOR TRANSMISSION (7-BIT ADDRESS)
Receiving Address
SDA
SCL
A7
S
A6
1
2
Data in
sampled
R/W
A5
A4
A3
A2
A1
3
4
5
6
7
8
ACK
Transmitting Data
ACK
9
D7
1
SCL held low
while CPU
responds to SSPIF
D6
D5
D4
D3
D2
D1
D0
2
3
4
5
6
7
8
9
P
Cleared in software
SSPIF
BF
Dummy read of SSPBUF
to clear BF flag
SSPBUF is written in software
From SSP Interrupt
Service Routine
CKP
Set bit after writing to SSPBUF
(the SSPBUF must be written to
before the CKP bit can be set)
DS41430A-page 154
 2010 Microchip Technology Inc.
 2010 Microchip Technology Inc.
CKP
UA
BF
SSPIF
1
SCL
S
1
2
1
4
1
5
0
6
7
A9 A8
UA is set indicating that
the SSPADD needs to be
updated
SSPBUF is written with
contents of SSPSR
3
1
8
9
ACK
R/W = 0
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
Clock is held low until
update of SSPADD has
taken place
2
3
1
4
1
Cleared in software
1
1
5
0
6
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
Bus Master
sends Restarts
condition
8
9
ACK
R/W = 1
4
5
6
Cleared in software
3
Write of SSPBUF
2
9
P
Completion of
data transmission
clears BF flag
8
ACK
CKP is automatically cleared in hardware holding SCL low
CKP is set in software, initiates transmission
7
D4 D3 D2 D1 D0
Dummy read of SSPBUF
to clear BF flag
1
D7 D6 D5
Transmitting Data Byte
Clock is held low until
CKP is set to ‘1’
Bus Master
sends Stop
condition
FIGURE 17-13:
SDA
Receive First Byte of Address
Clock is held low until
update of SSPADD has
taken place
PIC16F/LF720/721
I2C SLAVE MODE TIMING (TRANSMISSION 10-BIT ADDRESS)
DS41430A-page 155
PIC16F/LF720/721
17.2.7
CLOCK STRETCHING
2
During any SCL low phase, any device on the I C bus
may hold the SCL line low and delay, or pause, the
transmission of data. This “stretching” of a transmission
allows devices to slow down communication on the
bus. The SCL line must be constantly sampled by the
master to ensure that all devices on the bus have
released SCL for more data.
Stretching usually occurs after an ACK bit of a
transmission, delaying the first bit of the next byte. The
SSP module hardware automatically stretches for two
conditions:
• After a 10-bit address byte is received (update
SSPADD register)
• Anytime the CKP bit of the SSPCON register is
cleared by hardware
The module will hold SCL low until the CKP bit is set.
This allows the user slave software to update SSPBUF
with data that may not be readily available. In 10-bit
addressing modes, the SSPADD register must be
updated after receiving the first and second address
bytes. The SSP module will hold the SCL line low until
the SSPADD has a byte written to it. The UA bit of the
SSPSTAT register will be set, along with SSPIF,
indicating an address update is needed.
17.2.8
FIRMWARE MASTER MODE
Master mode of operation is supported in firmware
using interrupt generation on the detection of the Start
and Stop conditions. The Stop (P) and Start (S) bits of
the SSPSTAT register are cleared from a Reset or
when the SSP module is disabled (SSPEN cleared).
The Stop (P) and Start (S) bits will toggle based on the
Start and Stop conditions. Control of the I2C bus may
be taken when the P bit is set or the bus is Idle and both
the S and P bits are clear.
Refer to Application Note AN554, “Software
Implementation of I2C™ Bus Master” (DS00554) for more
information.
17.2.9
MULTI-MASTER MODE
In Multi-Master mode, the interrupt generation on the
detection of the Start and Stop conditions allow the
determination of when the bus is free. The Stop (P) and
Start (S) bits are cleared from a Reset or when the SSP
module is disabled. The Stop (P) and Start (S) bits will
toggle based on the Start and Stop conditions. Control
of the I2C bus may be taken when the P bit of the
SSPSTAT register is set or when the bus is Idle, and
both the S and P bits are clear. When the bus is busy,
enabling the SSP Interrupt will generate the interrupt
when the Stop condition occurs.
In Multi-Master operation, the SDA line must be monitored to see if the signal level is the expected output
level. This check only needs to be done when a high
level is output. If a high level is expected and a low level
is present, the device needs to release the SDA and
SCL lines (set TRIS bits). There are two stages where
this arbitration of the bus can be lost. They are the
Address Transfer and Data Transfer stages.
When the slave logic is enabled, the slave continues to
receive. If arbitration was lost during the address
transfer stage, communication to the device may be in
progress. If addressed, an ACK pulse will be
generated. If arbitration was lost during the data
transfer stage, the device will need to re-transfer the
data at a later time.
Refer to Application Note AN578, “Use of the SSP
Module in the I2C™ Multi-Master Environment”
(DS00578) for more information.
In Firmware Master mode, the SCL and SDA lines are
manipulated by setting/clearing the corresponding TRIS
bit(s). The output level is always low, irrespective of the
value(s) in the corresponding PORT register bit(s).
When transmitting a ‘1’, the TRIS bit must be set (input)
and a ‘0’, the TRIS bit must be clear (output).
The following events will cause the SSP Interrupt Flag
bit, SSPIF, to be set (SSP Interrupt will occur if
enabled):
• Start condition
• Stop condition
• Data transfer byte transmitted/received
Firmware Master mode of operation can be done with
either the Slave mode Idle (SSPM<3:0> = 1011), or
with either of the Slave modes in which interrupts are
enabled. When both master and slave functionality is
enabled, the software needs to differentiate the
source(s) of the interrupt.
DS41430A-page 156
 2010 Microchip Technology Inc.
PIC16F/LF720/721
17.2.10
CLOCK SYNCHRONIZATION
When the CKP bit is cleared, the SCL output is held low
once it is sampled low. Therefore, the CKP bit will not
stretch the SCL line until an external I2C master device
has already asserted the SCL line low. The SCL output
will remain low until the CKP bit is set and all other
devices on the I2C bus have released SCL. This
ensures that a write to the CKP bit will not violate the
minimum high time requirement for SCL (Figure 17-14).
FIGURE 17-14:
17.2.11
SLEEP OPERATION
While in Sleep mode, the I2C module can receive
addresses of data, and when an address match or
complete byte transfer occurs, wake the processor
from Sleep (if SSP interrupt is enabled).
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
SSPCON
 2010 Microchip Technology Inc.
DS41430A-page 157
PIC16F/LF720/721
REGISTER 17-3:
SSPCON: SYNCHRONOUS SERIAL PORT CONTROL REGISTER (I2C MODE)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
WCOL: Write Collision Detect bit
1 = The SSPBUF 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 = A byte is received while the SSPBUF register is still holding the previous byte. SSPOV is a “don’t
care” in Transmit mode. SSPOV must be cleared in software in either mode.
0 = No overflow
bit 5
SSPEN: Synchronous Serial Port Enable bit
1 = Enables the serial port and configures the SDA and SCL pins as serial port pins(2)
0 = Disables serial port and configures these pins as I/O port pins
bit 4
CKP: Clock Polarity Select bit
1 = Release control of SCL
0 = Holds clock low (clock stretch). (Used to ensure data setup time.)
bit 3-0
SSPM<3:0>: Synchronous Serial Port mode Select bits
0110 = I2C Slave mode, 7-bit address
0111 = I2C Slave mode, 10-bit address
1000 = Reserved
1001 = Load SSPMSK register at SSPADD SFR Address(1)
1010 = Reserved
1011 = I2C Firmware Controlled Master mode (Slave Idle)
1100 = Reserved
1101 = Reserved
1110 = I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled
1111 = I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled
Note 1: When this mode is selected, any reads or writes to the SSPADD SFR address accesses the SSPMSK register.
2: When enabled, these pins must be properly configured as input or output using the associated TRIS bit.
DS41430A-page 158
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 17-4:
SSPSTAT: SYNCHRONOUS SERIAL PORT STATUS REGISTER (I2C MODE)
R/W-0
R/W-0
R-0
R-0
R-0
R-0
R-0
R-0
SMP
CKE
D/A
P
S
R/W
UA
BF
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
SMP: SPI Data Input Sample Phase bit
1 = Slew Rate Control (limiting) disabled. Operating in I2C Standard mode (100 kHz and 1 MHz).
0 = Slew Rate Control (limiting) enabled. Operating in I2C Fast mode (400 kHz).
bit 6
CKE: SPI Clock Edge Select bit
This bit must be maintained clear. Used in SPI mode only.
bit 5
D/A: DATA/ADDRESS bit (I2C mode only)
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
This bit is cleared when the SSP module is disabled, or when the Start bit is detected last.
1 = Indicates that a Stop bit has been detected last (this bit is ‘0’ on Reset)
0 = Stop bit was not detected last
bit 3
S: Start bit
This bit is cleared when the SSP module is disabled, or when the Stop bit is detected last.
1 = Indicates that a Start bit has been detected last (this bit is ‘0’ on Reset)
0 = Start bit was not detected last
bit 2
R/W: READ/WRITE bit Information
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 ACK bit.
1 = Read
0 = Write
bit 1
UA: Update Address bit (10-bit I2C 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
Receive:
1 = Receive complete, SSPBUF is full
0 = Receive not complete, SSPBUF is empty
Transmit:
1 = Transmit in progress, SSPBUF is full
0 = Transmit complete, SSPBUF is empty
 2010 Microchip Technology Inc.
DS41430A-page 159
PIC16F/LF720/721
REGISTER 17-5:
SSPMSK: SSP MASK REGISTER
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
MSK7
MSK6
MSK5
MSK4
MSK3
MSK2
MSK1
MSK0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-1
MSK<7:1>: Mask bits
1 = The received address bit n is compared to SSPADD<n> to detect I2C address match
0 = The received address bit n is not used to detect I2C address match
bit 0
MSK<0>: Mask bit for I2C Slave Mode, 10-bit Address
I2C Slave mode, 10-bit Address (SSPM<3:0> = 0111):
1 = The received address bit ‘0’ is compared to SSPADD<0> to detect I2C address match
0 = The received address bit ‘0’ is not used to detect I2C address match
All other SSP modes: this bit has no effect.
SSPADD: SSP I2C ADDRESS REGISTER
REGISTER 17-6:
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ADD7
ADD6
ADD5
ADD4
ADD3
ADD2
ADD1
ADD0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
ADD<7:0>: Address bits
Received address
TABLE 17-3:
Name
INTCON
x = Bit is unknown
REGISTERS ASSOCIATED WITH I2C OPERATION
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
0000 000x
GIE
PEIE
TMR0IE
INTE
RABIE
TMR0IF
INTF
RABIF
0000 000x
PIR1
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
0000 0000
0000 0000
PIE1
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
0000 0000
0000 0000
SSPBUF
Synchronous Serial Port Receive Buffer/Transmit Register
xxxx xxxx
uuuu uuuu
SSPADD
ADD<7:0>
0000 0000
0000 0000
SSPCON
WCOL
SSPOV
SSPEN
SSPMSK(2)
CKP
SSPM3
SSPM2
SSPM1
SSPM0
MSK<7:0>
0000 0000
0000 0000
1111 1111
1111 1111
SSPSTAT
SMP(1)
CKE(1)
D/A
P
S
R/W
UA
BF
0000 0000
0000 0000
TRISB
TRISB7
TRISB6
TRISB5
TRISB4
—
—
—
—
1111 ----
1111 ----
Legend:
Note 1:
2:
x = unknown, u = unchanged, - = unimplemented locations read as ‘0’. Shaded cells are not used by SSP module in
I2C mode.
Maintain these bits clear in I2C mode.
Accessible only when SSPM<3:0> = 1001.
DS41430A-page 160
 2010 Microchip Technology Inc.
PIC16F/LF720/721
18.0
FLASH PROGRAM MEMORY
SELF READ/SELF WRITE
CONTROL
The Flash Program Memory is readable and writable
during normal operation of the device. This memory is
not directly mapped in the register file space. Instead,
it is indirectly addressed through the Special Function
Registers. There are six SFRs used to read/write this
memory:
•
•
•
•
•
•
PMCON1
PMCON2
PMDATL
PMDATH
PMADRL
PMADRH
18.1
Program Memory Read Operation
To read a program memory location, the user must
write two bytes of the address to the PMADRH and
PMADRL registers, then set control bit RD
(PMCON1<0>). Once the read control bit is set, the
Program Memory Read (PMR) controller uses the two
instruction cycles to read the data. This causes the two
instructions immediately following the ‘BSF PMCON1,
RD’ instruction to be ignored.
The data is available in the third cycle, following the set
of the RD bit, in the PMDATH and PMDATL registers.
PMDATL and PMDATH registers will hold this value
until another read is executed. See Example 18-1 and
Figure 18-1 for more information.
Note:
When interfacing the program memory block, the
PMDATL and PMDATH registers form a two byte word
which holds the 14-bit program data for reading, and
the PMADRL and PMADRH registers form a two byte
word which holds the 13-bit address of the program
Flash location being accessed. These devices have 2K
to 4K words of program memory with an address range
from 0000h to 0FFFh.
Interrupts must be disabled during the
time from setting PMCON1<0> (RD) to
the third instruction thereafter.
Devices without a full map of memory will shadow
accesses to unused blocks back to the implemented
memory.
EXAMPLE 18-1:
FLASH PROGRAM MEMORY READ
* This code block will read 1 word of program
* memory at the memory address:
PROG_ADDR_HI: PROG_ADDR_LO
*
data will be returned in the variables;
*
PROG_DATA_HI, PROG_DATA_LO
BANKSEL
MOVLW
MOVWF
MOVLW
MOVWL
PMADRL
PROG_ADDR_LO
PMADRL
PROG_ADDR_HI
PMADRH
; Select Bank 2
;
; Store LSB of address
;
; Store MSB of address
BANKSEL
BCF
BSF
NOP
NOP
BSF
PMCON1
INTCON,GIE
PMCON1,RD
INTCON,GIE
;
;
;
;
;
;
Select Bank 3
Disable interrupts
Initiate read
Ignored (Figure 18-1)
Ignored (Figure 18-1)
Restore interrupts
BANKSEL
MOVF
MOVWF
MOVF
MOVWF
PMDATL
PMDATL,W
PROG_DATA_LO
PMDATH,W
PROG_DATA_HI
;
;
;
;
;
Select Bank 2
Get LSB of word
Store in user location
Get MSB of word
Store in user location
 2010 Microchip Technology Inc.
DS41430A-page 161
PIC16F/LF720/721
FIGURE 18-1:
FLASH PROGRAM MEMORY READ CYCLE EXECUTION – NORMAL MODE
Q1
Q2
Flash ADDR
Q3
Q4
PC
Flash DATA
Q1
Q2
Q4
Q1
Q2
Q3
Q4
Q1
Q2
PMADRH, PMADRL
PC + 1
INSTR (PC)
INSTR (PC - 1)
Executed here
Q3
INSTR (PC + 1)
BSF PMCON1, RD
Executed here
Q3
Q1
Q2
Q3
Q4
PC + 4
PC+3
PMDATH, PMDATL
Forced NOP
Executed here
Q4
INSTR (PC + 3)
Forced NOP
Executed here
Q1
Q2
Q3
Q4
PC + 5
INSTR (PC + 4)
INSTR (PC + 3)
Executed here
INSTR (PC + 4)
Executed here
RD bit
PMDATH
PMDATL
Register
Force
NOP
Stop
PC
18.2
Code Protection
When the device is code-protected, the CPU may
continue to read and write the Flash program memory.
Depending on the settings of the Flash program
memory enable (WRT<1:0>) bits, the device may or
may not be able to write certain blocks of the program
memory. However, reads of the program memory are
allowed.
When the Flash program memory Code Protection
(CP) bit in the Configuration Word register is enabled,
the program memory is code-protected, and the device
programmer (ICSP™) cannot access data or program
memory.
Note:
18.3
Code-protect does not affect the CPU
from performing a read operation on the
program memory. For more information,
refer to Section 8.2 “Code Protection”.
18.4
PMCON1 and PMCON2 Registers
PMCON1 is the control register for the data program
memory accesses.
Control bits RD and WR initiate read and write,
respectively. These bits cannot be cleared, but only set
in software. They are cleared in hardware at the
completion of the read or write operation. The inability
to clear the WR bit in software prevents the accidental
premature termination of a write operation. Setting the
control bit WR initiates a write operation. For program
memory writes, WR initiates a write cycle if FREE = 0
and an erase cycle if FREE = 1.
The WREN bit, when set, will allow a write operation.
On power-up, the WREN bit is clear. PMCON2 is not a
physical register. Reading PMCON2 will read all ‘0’s.
The PMCON2 register is used exclusively in the Flash
memory write sequence.
PMADRH and PMADRL Registers
The PMADRH:PMADRL register pair can address up
to a maximum of 4K words of program Flash. The Most
Significant Byte (MSB) of the address is written to the
PMADRH register and the Least Significant Byte (LSB)
is written to the PMADRL register.
DS41430A-page 162
 2010 Microchip Technology Inc.
PIC16F/LF720/721
18.5
Writing to Flash Program Memory
A word of the Flash program memory may only be
written to if the word is in an unprotected segment of
memory.
Flash program memory may only be written to if the
destination address is in a segment of memory that is
not write-protected, as defined in bits WRT<1:0> of the
Configuration Word Register 2. Flash program memory
must be written in 32-word rows. See Figure 18-2 for
more details. A row consists of 32 words with sequential addresses, with a lower boundary defined by an
address, where PMADR<4:0>= 00000. All row writes to
program memory are done as 32-word erase and one
to 32-word write operations. The write operation is
edge-aligned. Crossing boundaries is not recommended, as the operation will only affect the new
boundary, wrapping the data values at the same time.
Once the write control bit is set, the Program Memory
(PM) controller will immediately write the data. Program
execution is stalled while the write is in progress.
To erase a program memory row, the address of the
row to erase must be loaded into the
PMADRH:PMADRL register pair. A row consists of 32
words so, when selecting a row, PMADR<4:0> are
ignored. After the Address has been set up, then the
following sequence of events must be executed:
1.
2.
3.
Set the WREN and FREE control bits of the
PMCON1 register.
Write 55h, then AAh, to PMCON2 (Flash
programming sequence).
Set the WR control bit of the PMCON1 register.
To write program data, it must first be loaded into the
buffer latches (see Figure 18-2). This is accomplished
by first writing the destination address to PMADRL and
PMADRH and then writing the data to PMDATA and
PMDATH. After the address and data have been set
up, then the following sequence of events must be executed:
1.
2.
3.
Set the WREN control bit of the PMCON1
register.
Write 55h, then AAh, to PMCON2 (Flash
programming sequence).
Set the WR control bit of the PMCON1 register.
All 32 buffer register locations should be written to with
correct data. If less than 32 words are being written to
in the block of 32 words, then a read from the program
memory location(s) not being written to must be
performed. This takes the data from the program
location(s) not being written and loads it into the
PMDATL and PMDATH registers. Then, the sequence
of events to transfer data to the buffer registers must be
executed.
 2010 Microchip Technology Inc.
When the LWLO bit is ‘1’, the write sequence will only
load the buffer register and will not actually initiate the
write to program Flash:
1.
2.
3.
Set the WREN and LWLO bits of the PMCON1
register.
Write 55h, then AAh, to PMCON2 (Flash
programming unlock sequence).
Set control bit WR of the PMCON1 register to
begin the write operation.
Note:
Self-write execution to Flash memory cannot be done while running in low power
PFM and Voltage Regulator modes.
Therefore, executing a self-write will put
the PFM and voltage regulator into High
Power mode for the duration of the
sequence.
To transfer data from the buffer registers to the program
memory, the last word to be written should be written to
the PMDATH:PMDATL register pair. Then, the
following sequence of events must be executed:
1.
2.
3.
4.
Clear the LWLO bit of the PMCON1 Register.
Write 55h, then AAh, to PMCON2 (Flash
programming sequence).
Set control bit WR of the PMCON1 register to
begin the write operation.
Two NOP must follow the setting of the WR bit.
This is necessary to provide time for the address and to
be provided to the program Flash memory to be put in
the write latches.
Note:
An ICD break that occurs during the 55h AAh - Set WR bit sequence will interrupt
the timing of the sequence and prevent
the unlock sequence from occurring. In
this case, no write will be initiated, as
there was no operation to complete.
No automatic erase occurs upon the initiation of the
write; if the program Flash needs to be erased before
writing, the row (32 words) must be previously erased.
After the “BSF PMCON1, WR” instruction, the processor
requires two cycles to set up the erase/write operation.
The user must place two NOP instructions after the WR
bit is set. These two instructions will also be forced in
hardware to NOP, but if an ICD break occurs at this
point, the forcing to NOP will be lost.
DS41430A-page 163
PIC16F/LF720/721
Since data is being written to buffer registers, the
writing of the first 31 words of the block appears to
occur immediately. The processor will halt internal
operations for the typical 4ms, only during the cycle in
which the erase takes place (i.e., the last word of the
32-word block erase). This is not Sleep mode as the
clocks and peripherals will continue to run. After the 32word write cycle, the processor will resume operation
with the third instruction after the PMCON1 write
instruction.
FIGURE 18-2:
BLOCK OF 32 WRITES TO FLASH PROGRAM MEMORY
7
5
PMDATH
14
PMADRL<4:0> = 00000
PMDATL
6
8
14
14
PMADRL<4:0> = 00010
PMADRL<4:0> = 00001
Buffer Register
0
0 7
Buffer Register
14
PMADRL<4:0> = 11111
Buffer Register
Buffer Register
Program Memory
An example of the complete 32-word write sequence is
shown in Example 18-2. The initial address is loaded
into the PMADRH:PMADRL register pair; the 32 words
of data are loaded using indirect addressing.
DS41430A-page 164
 2010 Microchip Technology Inc.
PIC16F/LF720/721
EXAMPLE 18-2:
;
;
;
;
;
WRITING TO FLASH PROGRAM MEMORY
This write routine assumes the following:
1. A valid starting address (the least significant bits = ‘00000’)is loaded in ADDRH:ADDRL
2. The 64 bytes of data are loaded, starting at the address in DATADDR
3. ADDRH, ADDRL and DATADDR are all located in shared data memory 0x70 - 0x7f
Required
Sequence
LOOP
BANKSEL
MOVF
MOVWF
MOVF
MOVWF
MOVF
MOVWF
MOVF
MOVWF
PMADRH
ADDRH,W
PMADRH
ADDRL,W
PMADRL
DATAADDRL,W
FSR0L
DATAADDRH,W
FSR0H
;
;
;
;
;
;
;
;
;
MOVIW
MOVWF
MOVIW
MOVWF
BSF
BSF
INDF0++
PMDATL
INDF0++
PMDATH
PMCON1,WREN
PMCON1,LWLO
;
;
;
;
;
;
Load first data byte into lower
MOVLW
MOVWF
MOVLW
MOVWF
BSF
55h
PMCON2
AAh
PMCON2
PMCON1,WR
;
;
;
;
;
Start of required write sequence:
Write 55h
;
;
;
;
Any instructions here are ignored as processor
halts to begin write sequence
processor will stop here and wait for write complete
after write processor continues with 3rd instruction
NOP
NOP
Load initial data address
Load initial data address
Load second data byte into upper
Enable writes
Only Load Write Latches
Write AAh
Set WR bit to begin write
MOVF
XORLW
ANDLW
BTFSC
GOTO
PMADR,W
0x1F
0x1F
STATUS,Z
START_WRITE
; Check if lower five bits of address are ‘11111’
; Check if we’re on the last of 8 addresses
;
; Exit if last of 32 words,
;
INCF
GOTO
PMADR,F
LOOP
; Still loading latches Increment address
; Write next latches
PMCON1,LWLO
; No more Latches only; Actually start write
55h
PMCON2
AAh
PMCON2
PMCON1,WR
;
;
;
;
;
Start of required write sequence:
Write 55h
PMCON1,WREN
;
;
;
;
;
Any instructions here are ignored as processor
halts to begin write sequence
processor will stop here and wait for write complete
after write processor continues with 3rd instruction
Disable writes
START_WRITE
BCF
Required
Sequence
Bank 3
Load initial address
MOVLW
MOVWF
MOVLW
MOVWF
BSF
NOP
NOP
BCF
 2010 Microchip Technology Inc.
Write AAh
Set WR bit to begin write
DS41430A-page 165
PIC16F/LF720/721
18.6
Protection Against Spurious Write
There are conditions when the device should not write
to the program memory. To protect against spurious
writes, various mechanisms have been built in. On
power-up, WREN is cleared. Also, the Power-up Timer
(64 ms duration) prevents program memory writes.
The write initiates sequence and the WREN bit helps
prevent an accidental write during brown-out, power
glitch or software malfunction.
18.7
Operation During Code-Protect
When the device is code-protected, the CPU is able to
read and write unscrambled data to the program
memory.
18.8
Operation During Write-Protect
When the program memory is write-protected, the CPU
can read and execute from the program memory.
The portions of program memory that are
write-protected can be modified by the CPU using the
PMCON registers, but the protected program memory
cannot be modified using ICSP mode.
REGISTER 18-1:
PMCON1: PROGRAM MEMORY CONTROL 1 REGISTER
U-1
R/W-0/0
R/W-0/0
R/W/HC-0/0
U-0
R/W-0/0
R/S/HC-0/0
R/S/HC-0/0
—
CFGS
LWLO
FREE
—
WREN
WR
RD
bit 7
bit 0
Legend:
S = Setable bit, cleared in hardware
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
Unimplemented: Read as ‘1’
bit 6
CFGS: Flash Program/Data EEPROM or Configuration Select bit
1 = Accesses Configuration, user ID and device ID registers
0 = Accesses Flash program
bit 5
LWLO: Load Write Latches Only bit
1=
The next WR command does not initiate a write to the PFM; only the program memory
latches are updated.
0=
The next WR command writes a value from EEDATH:EEDATL into program memory latches
and initiates a write to the PFM of all the data stored in the program memory latches.
bit 4
FREE: Program Flash Erase Enable bit
1=
Perform an program Flash erase operation on the next WR command (cleared by hardware
after completion of erase).
0=
Perform a program Flash write operation on the next WR command.
bit 3
Unimplemented: Read as ‘0’
bit 2
WREN: Program/Erase Enable bit
1 = Allows program/erase cycles.
0 = Inhibits programming/erasing of Program Flash and Data EEPROM.
bit 1
WR: Write Control bit
1 = Initiates a program Flash program/erase operation.
The operation is self-timed and the bit is cleared by hardware once operation is complete.
The WR bit can only be set (not cleared) in software.
0 = Program/erase operation to the Flash is complete and inactive.
bit 0
RD: Read Control bit
1 = Initiates an program memory read (The RD is cleared in hardware; the RD bit can only be set
(not cleared) in software).
0 = Does not initiate a program memory read
DS41430A-page 166
 2010 Microchip Technology Inc.
PIC16F/LF720/721
REGISTER 18-2:
PMDATH: PROGRAM MEMORY DATA HIGH REGISTER
U-0
U-0
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
—
—
PMD13
PMD12
PMD11
PMD10
PMD9
PMD8
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 5-0
PMD<13:8>: The value of the program memory word pointed to by PMADRH and PMADRL after a
program memory read command.
REGISTER 18-3:
PMDATL: PROGRAM MEMORY DATA LOW REGISTER
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
PMD7
PMD6
PMD5
PMD4
PMD3
PMD2
PMD1
PMD0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
x = Bit is unknown
PMD<7:0>: The value of the program memory word pointed to by PMADRH and PMADRL after a
program memory read command.
REGISTER 18-4:
PMADRH: PROGRAM MEMORY ADDRESS HIGH REGISTER
U-0
U-0
U-0
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
—
—
—
PMA12
PMA11
PMA10
PMA9
PMA8
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-5
Unimplemented: Read as ‘0’
bit 4-0
PMA<12:8>: Program Memory Read Address bits
 2010 Microchip Technology Inc.
x = Bit is unknown
DS41430A-page 167
PIC16F/LF720/721
REGISTER 18-5:
PMADRL: PROGRAM MEMORY ADDRESS LOW REGISTER
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
R/W-x
PMA7
PMA6
PMA5
PMA4
PMA3
PMA2
PMA1
PMA0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
bit 7-0
PMA<7:0>: Program Memory Read Address bits
TABLE 18-1:
Name
PMCON1
SUMMARY OF REGISTERS ASSOCIATED WITH PROGRAM MEMORY READ
Bit 7
—
PMCON2
PMADRH
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on all
other Resets
CFGS
LWLO
FREE
—
WREN
WR
RD
1000 -000
1000 -000
—
—
—
—
—
Program Memory Read Address Register High Byte
Program Memory Read Address Register Low Byte
PMDATL
Legend:
Bit 6
Program Memory Control Register 2 (not a physical register)
PMADRL
PMDATH
x = Bit is unknown
Program Memory Read Data Register High Byte
Program Memory Read Data Register Low Byte
---- ----
---- ----
---0 0000
---0 0000
0000 0000
0000 0000
--xx xxxx
--xx xxxx
xxxx xxxx
xxxx xxxx
x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the program memory read.
DS41430A-page 168
 2010 Microchip Technology Inc.
PIC16F/LF720/721
19.0
POWER-DOWN MODE (SLEEP)
19.1
Wake-up from Sleep
The Power-down mode is entered by executing a
SLEEP instruction.
The device can wake-up from Sleep through one of the
following events:
If the Watchdog Timer is enabled:
1.
2.
•
•
•
•
•
WDT will be cleared but keeps running.
PD bit of the STATUS register is cleared.
TO bit of the STATUS register is set.
Oscillator driver is turned off.
I/O ports maintain the status they had before
SLEEP was executed (driving high, low or highimpedance).
For lowest current consumption in this mode, all I/O
pins should be either at VDD or VSS, with no external
circuitry drawing current from the I/O pin. I/O pins that
are high-impedance inputs should be pulled high or low
externally to avoid switching currents caused by floating inputs. The T0CKI input should also be at VDD or
VSS for lowest current consumption. The contribution
from on-chip pull-ups on PORTB should be considered.
The MCLR pin must be at a logic high level when
external MCLR is enabled.
Note:
A Reset generated by a WDT time-out
does not drive MCLR pin low.
3.
External Reset input on MCLR pin.
Watchdog Timer wake-up (if WDT was
enabled).
Interrupt from RA2/INT pin, PORTB change or a
peripheral interrupt.
The first event will cause a device Reset. The two latter
events are considered a continuation of program
execution. The TO and PD bits in the STATUS register
can be used to determine the cause of a device Reset.
The PD bit, which is set on power-up, is cleared when
Sleep is invoked. TO bit is cleared if WDT wake-up
occurred.
The following peripheral interrupts can wake the device
from Sleep:
1.
2.
3.
4.
5.
6.
7.
TMR1 interrupt. Timer1 must be operating as an
asynchronous counter.
USART Receive Interrupt (Synchronous Slave
mode only)
A/D conversion (when A/D clock source is RC)
Interrupt-on-change
External interrupt from INT pin
Capture event on CCP1
SSP interrupt in SPI or I2C Slave mode
Other peripherals cannot generate interrupts since
during Sleep, no on-chip clocks are present.
When the SLEEP instruction is being executed, the next
instruction (PC + 1) is prefetched. For the device to
wake-up through an interrupt event, the corresponding
interrupt enable bit must be set (enabled). Wake-up is
regardless of the state of the GIE bit. If the GIE bit is
clear (disabled), the device continues execution at the
instruction after the SLEEP instruction. If the GIE bit is
set (enabled), the device executes the instruction after
the SLEEP instruction, then branches to the interrupt
address (0004h). In cases where the execution of the
instruction following SLEEP is not desirable, the user
should have a NOP after the SLEEP instruction.
Note:
If the global interrupts are disabled (GIE is
cleared), but any interrupt source has both
its interrupt enable bit and the corresponding interrupt flag bits set, the device will
immediately wake-up from Sleep. The
SLEEP instruction is completely executed.
The WDT is cleared when the device wakes up from
Sleep, regardless of the source of wake-up.
 2010 Microchip Technology Inc.
DS41430A-page 169
PIC16F/LF720/721
19.2
Wake-up Using Interrupts
Even if the flag bits were checked before executing a
SLEEP instruction, it may be possible for flag bits to
become set before the SLEEP instruction completes. To
determine whether a SLEEP instruction executed, test
the PD bit. If the PD bit is set, the SLEEP instruction
was executed as a NOP.
When global interrupts are disabled (GIE cleared) and
any interrupt source has both its interrupt enable bit
and interrupt flag bit set, one of the following will occur:
• If the interrupt occurs before the execution of a
SLEEP instruction, the SLEEP instruction will
complete as a NOP. Therefore, the WDT and WDT
prescaler and postscaler (if enabled) will not be
cleared, the TO bit will not be set and the PD bit
will not be cleared.
• If the interrupt occurs during or after the
execution of a SLEEP instruction, the device will
immediately wake-up from Sleep. The SLEEP
instruction will be completely executed before the
wake-up. Therefore, the WDT and WDT prescaler
and postscaler (if enabled) will be cleared, the TO
bit will be set and the PD bit will be cleared.
FIGURE 19-1:
To ensure that the WDT is cleared, a CLRWDT instruction
should be executed before a SLEEP instruction.
WAKE-UP FROM SLEEP THROUGH INTERRUPT
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Oscillator
TOST(1)
CLKOUT(3)
INT pin
INTF flag
(INTCON reg.)
Interrupt Latency (2)
GIE bit
(INTCON reg.)
Processor in
Sleep
Instruction Flow
PC
Instruction
Fetched
Instruction
Executed
Note
1:
2:
3:
PC
PC + 1
Inst(PC) = Sleep
Inst(PC - 1)
Inst(PC + 1)
Inst(PC + 2)
Sleep
Inst(PC + 1)
Dummy Cycle
0004h
0005h
Inst(0004h)
Inst(0005h)
Dummy Cycle
Inst(0004h)
SUMMARY OF REGISTERS ASSOCIATED WITH POWER-DOWN MODE
Name
Bit 7
Bit 6
IOCB
IOCB7
GIE
PIE1
PIR1
Legend:
PC + 2
PC + 2
TOST = 1024 TOSC (drawing not to scale). This delay does not apply to EC mode.
GIE = 1 assumed. In this case after wake-up, the processor jumps to 0004h. If GIE = 0, execution will continue in-line.
CLKOUT is not available in EC Oscillator mode, but shown here for timing reference.
TABLE 19-1:
INTCON
PC + 2
Bit 5
Bit 4
Bit 3
Bit 2
IOCB6
IOCB5
IOCB4
—
—
PEIE
TMR0IE
INTE
RABIE
TMR0IF
TMR1GIE
ADIE
RCIE
TXIE
SSPIE
CCP1IE
TMR1GIF
ADIF
RCIF
TXIF
SSPIF
CCP1IF
Bit 0
Value on
POR, BOR
Value on all
other Resets
—
—
0000 ----
0000 ----
INTF
RABIF
0000 000x
0000 000x
TMR2IE
TMR1IE
0000 0000
0000 0000
TMR2IF
TMR1IF
0000 0000
0000 0000
Bit 1
x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used in Power-Down mode.
DS41430A-page 170
 2010 Microchip Technology Inc.
PIC16F/LF720/721
20.0
IN-CIRCUIT SERIAL
PROGRAMMING™ (ICSP™)
The device is placed into Program/Verify mode by
holding the ICSPCLK and ICSPDAT pins low then
raising the voltage on MCLR/VPP from 0V to VPP. In
Program/Verify mode the program memory, user IDs and
the Configuration Words are programmed through serial
communications. The ICSPDAT pin is a bidirectional I/O
used for transferring the serial data and the ISCPCLK pin
is the clock input. For more information on ICSP™ refer
to
the
“PIC16F72x/PIC16LF72x
Programming
Specification” (DS41332).
ICSP™ programming allows customers to manufacture
circuit boards with unprogrammed devices. Programming
can be done after the assembly process, allowing the
device to be programmed with the most recent firmware
or a custom firmware. Five pins are needed for ICSP™
programming:
• ICSPCLK
• ICSPDAT
• MCLR/VPP
• VDD
• VSS
FIGURE 20-1:
Note:
The MPLAB® ICD 2 produces a VPP voltage greater than the maximum VPP specification of the PIC16F/LF720/721. When
using this programmer, an external circuit,
such as the AC164112 MPLAB ICD 2 VPP
voltage limiter, is required to keep the VPP
voltage within the device specifications.
TYPICAL CONNECTION FOR ICSP™ PROGRAMMING
External
Programming
Signals
VDD
Device to be
Programmed
VDD
VDD
10k
VPP
MCLR/VPP
GND
VSS
Data
ICSPDAT
Clock
ICSPCLK
*
*
*
To Normal Connections
* Isolation devices (as required).
 2010 Microchip Technology Inc.
DS41430A-page 171
PIC16F/LF720/721
NOTES:
DS41430A-page 172
 2010 Microchip Technology Inc.
PIC16F/LF720/721
21.0
INSTRUCTION SET SUMMARY
The PIC16F/LF720/721 instruction set is highly
orthogonal and is comprised of three basic categories:
• Byte-oriented operations
• Bit-oriented operations
• Literal and control operations
TABLE 21-1:
OPCODE FIELD
DESCRIPTIONS
Field
Description
Register file address (0x00 to 0x7F)
f
W
Working register (accumulator)
b
Bit address within an 8-bit file register
k
Literal field, constant data or label
x
Don’t care location (= 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.
Table 21-2 lists the instructions recognized by the
MPASMTM assembler.
d
For byte-oriented instructions, ‘f’ represents a file
register designator and ‘d’ represents a destination
designator. The file register designator specifies which
file register is to be used by the instruction.
Destination select; d = 0: store result in W,
d = 1: store result in file register f.
Default is d = 1.
PC
Program Counter
TO
Time-out bit
Each PIC16 instruction is a 14-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 formats for each of the categories
is presented in Figure 21-1, while the various opcode
fields are summarized in Table 21-1.
The destination designator specifies where the result of
the operation is to be placed. If ‘d’ is zero, the result is
placed in the W register. If ‘d’ is one, the result is placed
in the file register specified in the instruction.
For bit-oriented instructions, ‘b’ represents a bit field
designator, which selects the bit affected by the
operation, while ‘f’ represents the address of the file in
which the bit is located.
For literal and control operations, ‘k’ represents an 8bit or 11-bit constant, or literal value.
One instruction cycle consists of four oscillator periods;
for an oscillator frequency of 4 MHz, this gives a
nominal instruction execution time of 1 s. All
instructions are executed within a single instruction
cycle, unless a conditional test is true, or the program
counter is changed as a result of an instruction. When
this occurs, the execution takes two instruction cycles,
with the second cycle executed as a NOP.
Carry bit
C
DC
Digit carry bit
Zero bit
Z
PD
Power-down bit
FIGURE 21-1:
GENERAL FORMAT FOR
INSTRUCTIONS
Byte-oriented file register operations
13
8 7 6
OPCODE
d
f (FILE #)
0
d = 0 for destination W
d = 1 for destination f
f = 7-bit file register address
Bit-oriented file register operations
13
10 9
7 6
OPCODE
b (BIT #)
f (FILE #)
0
b = 3-bit bit address
f = 7-bit file register address
All instruction examples use the format ‘0xhh’ to
represent a hexadecimal number, where ‘h’ signifies a
hexadecimal digit.
Literal and control operations
21.1
Read-Modify-Write Operations
Any instruction that specifies a file register as part of
the instruction performs a Read-Modify-Write (R-M-W)
operation. The register is read, the data is modified,
and the result is stored according to either the instruction, or the destination designator ‘d’. A read operation
is performed on a register even if the instruction writes
to that register.
For example, a CLRF PORTB instruction will read
PORTB, clear all the data bits, then write the result
back to PORTB. This example would have the unintended consequence of clearing the condition that set
the RABIF flag.
 2010 Microchip Technology Inc.
General
13
8
7
OPCODE
0
k (literal)
k = 8-bit immediate value
CALL and GOTO instructions only
13
11
OPCODE
10
0
k (literal)
k = 11-bit immediate value
DS41430A-page 173
PIC16F/LF720/721
TABLE 21-2:
PIC16F/LF720/721 INSTRUCTION SET
Mnemonic,
Operands
14-Bit Opcode
Description
Cycles
MSb
LSb
Status
Affected
Notes
BYTE-ORIENTED FILE REGISTER OPERATIONS
ADDWF
ANDWF
CLRF
CLRW
COMF
DECF
DECFSZ
INCF
INCFSZ
IORWF
MOVF
MOVWF
NOP
RLF
RRF
SUBWF
SWAPF
XORWF
f, d
f, d
f
–
f, d
f, d
f, d
f, d
f, d
f, d
f, d
f
–
f, d
f, d
f, d
f, d
f, d
Add W and f
AND W with f
Clear f
Clear W
Complement f
Decrement f
Decrement f, Skip if 0
Increment f
Increment f, Skip if 0
Inclusive OR W with f
Move f
Move W to f
No Operation
Rotate Left f through Carry
Rotate Right f through Carry
Subtract W from f
Swap nibbles in f
Exclusive OR W with f
BCF
BSF
BTFSC
BTFSS
f, b
f, b
f, b
f, b
Bit Clear f
Bit Set f
Bit Test f, Skip if Clear
Bit Test f, Skip if Set
1
1
1
1
1
1
1(2)
1
1(2)
1
1
1
1
1
1
1
1
1
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
dfff
dfff
lfff
0xxx
dfff
dfff
dfff
dfff
dfff
dfff
dfff
lfff
0xx0
dfff
dfff
dfff
dfff
dfff
ffff
ffff
ffff
xxxx
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
0000
ffff
ffff
ffff
ffff
ffff
00bb
01bb
10bb
11bb
bfff
bfff
bfff
bfff
ffff
ffff
ffff
ffff
111x
1001
0kkk
0000
1kkk
1000
00xx
0000
01xx
0000
0000
110x
1010
kkkk
kkkk
kkkk
0110
kkkk
kkkk
kkkk
0000
kkkk
0000
0110
kkkk
kkkk
kkkk
kkkk
kkkk
0100
kkkk
kkkk
kkkk
1001
kkkk
1000
0011
kkkk
kkkk
0111
0101
0001
0001
1001
0011
1011
1010
1111
0100
1000
0000
0000
1101
1100
0010
1110
0110
C, DC, Z
Z
Z
Z
Z
Z
Z
Z
Z
C
C
C, DC, Z
Z
1, 2
1, 2
2
1, 2
1, 2
1, 2, 3
1, 2
1, 2, 3
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
BIT-ORIENTED FILE REGISTER OPERATIONS
1
1
1 (2)
1 (2)
01
01
01
01
1, 2
1, 2
3
3
LITERAL AND CONTROL OPERATIONS
ADDLW
ANDLW
CALL
CLRWDT
GOTO
IORLW
MOVLW
RETFIE
RETLW
RETURN
SLEEP
SUBLW
XORLW
Note 1:
2:
3:
k
k
k
–
k
k
k
–
k
–
–
k
k
Add literal and W
AND literal with W
Call Subroutine
Clear Watchdog Timer
Go to address
Inclusive OR literal with W
Move literal to W
Return from interrupt
Return with literal in W
Return from Subroutine
Go into Standby mode
Subtract W from literal
Exclusive OR literal with W
1
1
2
1
2
1
1
2
2
2
1
1
1
11
11
10
00
10
11
11
00
11
00
00
11
11
C, DC, Z
Z
TO, PD
Z
TO, PD
C, DC, Z
Z
When an I/O register is modified as a function of itself (e.g., MOVF PORTA, 1), 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 to the Timer0 module.
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.
DS41430A-page 174
 2010 Microchip Technology Inc.
PIC16F/LF720/721
21.2
Instruction Descriptions
ADDLW
Add literal and W
Syntax:
[ label ] ADDLW
Operands:
0  k  255
Operation:
(W) + k  (W)
Status Affected:
C, DC, Z
Description:
The contents of the W register
are added to the eight-bit literal ‘k’
and the result is placed in the
W register.
k
BCF
Bit Clear f
Syntax:
[ label ] BCF
Operands:
0  f  127
0b7
Operation:
0  (f<b>)
Status Affected:
None
Description:
Bit ‘b’ in register ‘f’ is cleared.
BSF
Bit Set f
Syntax:
[ label ] BSF
f,b
ADDWF
Add W and f
Syntax:
[ label ] ADDWF
Operands:
0  f  127
d 0,1
Operands:
0  f  127
0b7
Operation:
(W) + (f)  (destination)
Operation:
1  (f<b>)
Status Affected:
C, DC, Z
Status Affected:
None
Description:
Add the contents of the W register
with register ‘f’. If ‘d’ is ‘0’, the
result is stored in the W register. If
‘d’ is ‘1’, the result is stored back
in register ‘f’.
Description:
Bit ‘b’ in register ‘f’ is set.
ANDLW
AND literal with W
BTFSC
Bit Test f, Skip if Clear
Syntax:
[ label ] ANDLW
Syntax:
[ label ] BTFSC f,b
Operands:
0  k  255
Operands:
Operation:
(W) .AND. (k)  (W)
0  f  127
0b7
Status Affected:
Z
Operation:
skip if (f<b>) = 0
Description:
The contents of W register are
AND’ed with the eight-bit literal
‘k’. The result is placed in the W
register.
Status Affected:
None
Description:
If bit ‘b’ in register ‘f’ is ‘1’, the next
instruction is executed.
If bit ‘b’ in register ‘f’ is ‘0’ the next
instruction is discarded and a NOP
is executed instead, making this a
2-cycle instruction.
ANDWF
f,d
k
AND W with f
Syntax:
[ label ] ANDWF
Operands:
0  f  127
d 0,1
Operation:
(W) .AND. (f)  (destination)
f,d
Status Affected:
Z
Description:
AND the W register with register
‘f’. If ‘d’ is ‘0’, the result is stored in
the W register. If ‘d’ is ‘1’, the
result is stored back in register ‘f’.
 2010 Microchip Technology Inc.
f,b
DS41430A-page 175
PIC16F/LF720/721
BTFSS
Bit Test f, Skip if Set
CLRWDT
Clear Watchdog Timer
Syntax:
[ label ] BTFSS f,b
Syntax:
[ label ] CLRWDT
Operands:
0  f  127
0b<7
Operands:
None
Operation:
00h  WDT
0  WDT prescaler,
1  TO
1  PD
Status Affected:
TO, PD
Description:
CLRWDT instruction resets the
Watchdog Timer. It also resets the
prescaler of the WDT.
Status bits TO and PD are set.
COMF
Complement f
Syntax:
[ label ] COMF
Operands:
0  f  127
d  [0,1]
Operation:
skip if (f<b>) = 1
Status Affected:
None
Description:
If bit ‘b’ in register ‘f’ is ‘0’, the next
instruction is executed.
If bit ‘b’ is ‘1’, then the next
instruction is discarded and a NOP
is executed instead, making this a
2-cycle instruction.
CALL
Call Subroutine
Syntax:
[ label ] CALL
Operands:
0  k  2047
Operation:
(PC)+ 1 TOS,
k  PC<10:0>,
(PCLATH<4:3>)  PC<12:11>
k
f,d
Operation:
(f)  (destination)
Status Affected:
Z
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’.
DECF
Decrement f
Syntax:
[ label ] DECF f,d
Status Affected:
None
Description:
Call Subroutine. First, return
address (PC + 1) is pushed onto
the stack. The eleven-bit
immediate address is loaded into
PC bits <10:0>. The upper bits of
the PC are loaded from PCLATH.
CALL is a two-cycle instruction.
CLRF
Clear f
Syntax:
[ label ] CLRF
Operands:
0  f  127
Operands:
Operation:
00h  (f)
1Z
0  f  127
d  [0,1]
Operation:
(f) - 1  (destination)
Status Affected:
Z
Status Affected:
Z
Description:
The contents of register ‘f’ are
cleared and the Z bit is set.
Description:
Decrement register ‘f’. If ‘d’ is ‘0’,
the result is stored in the W
register. If ‘d’ is ‘1’, the result is
stored back in register ‘f’.
CLRW
Clear W
Syntax:
[ label ] CLRW
f
Operands:
None
Operation:
00h  (W)
1Z
Status Affected:
Z
Description:
W register is cleared. Zero bit (Z)
is set.
DS41430A-page 176
 2010 Microchip Technology Inc.
PIC16F/LF720/721
DECFSZ
Decrement f, Skip if 0
INCFSZ
Increment f, Skip if 0
Syntax:
[ label ] DECFSZ f,d
Syntax:
[ label ]
Operands:
0  f  127
d  [0,1]
Operands:
0  f  127
d  [0,1]
Operation:
(f) - 1  (destination);
skip if result = 0
Operation:
(f) + 1  (destination),
skip if result = 0
Status Affected:
None
Status Affected:
None
Description:
The contents of register ‘f’ are
decremented. If ‘d’ is ‘0’, the result
is placed in the W register. If ‘d’ is
‘1’, the result is placed back in
register ‘f’.
If the result is ‘1’, the next
instruction is executed. If the
result is ‘0’, then a NOP is
executed instead, making it a
2-cycle instruction.
Description:
The contents of register ‘f’ are
incremented. If ‘d’ is ‘0’, the result
is placed in the W register. If ‘d’ is
‘1’, the result is placed back in
register ‘f’.
If the result is ‘1’, the next
instruction is executed. If the
result is ‘0’, a NOP is executed
instead, making it a 2-cycle
instruction.
GOTO
Unconditional Branch
IORLW
Syntax:
[ label ]
Syntax:
[ label ]
Operands:
0  k  2047
Operands:
0  k  255
Operation:
k  PC<10:0>
PCLATH<4:3>  PC<12:11>
Operation:
(W) .OR. k  (W)
Status Affected:
Z
Status Affected:
None
Description:
Description:
GOTO is an unconditional branch.
The eleven-bit immediate value is
loaded into PC bits <10:0>. The
upper bits of PC are loaded from
PCLATH<4:3>. GOTO is a
two-cycle instruction.
The contents of the W register are
OR’ed with the eight-bit literal ‘k’.
The result is placed in the
W register.
INCF
Increment f
IORWF
Inclusive OR W with f
Syntax:
[ label ]
Syntax:
[ label ]
Operands:
0  f  127
d  [0,1]
Operands:
0  f  127
d  [0,1]
Operation:
(f) + 1  (destination)
Operation:
(W) .OR. (f)  (destination)
Status Affected:
Z
Status Affected:
Z
Description:
The contents of register ‘f’ are
incremented. If ‘d’ is ‘0’, the result
is placed in the W register. If ‘d’ is
‘1’, the result is placed back in
register ‘f’.
Description:
Inclusive OR the W register with
register ‘f’. If ‘d’ is ‘0’, the result is
placed in the W register. If ‘d’ is
‘1’, the result is placed back in
register ‘f’.
GOTO k
INCF f,d
 2010 Microchip Technology Inc.
INCFSZ f,d
Inclusive OR literal with W
IORLW k
IORWF
f,d
DS41430A-page 177
PIC16F/LF720/721
MOVF
Move f
Syntax:
[ label ]
Operands:
0  f  127
d  [0,1]
MOVF f,d
MOVWF
Move W to f
Syntax:
[ label ]
MOVWF
Operands:
0  f  127
Operation:
(W)  (f)
f
Operation:
(f)  (dest)
Status Affected:
None
Status Affected:
Z
Description:
Description:
The contents of register f is
moved to a destination dependent
upon the status of d. If d = 0,
destination is W register. If d = 1,
the destination is file register f
itself. d = 1 is useful to test a file
register since status flag Z is
affected.
Move data from W register to
register ‘f’.
Words:
1
Cycles:
1
Words:
1
Cycles:
1
Example:
MOVF
Example:
MOVW
F
OPTION
Before Instruction
OPTION =
W
=
After Instruction
OPTION =
W
=
FSR, 0
0xFF
0x4F
0x4F
0x4F
After Instruction
W =
value in FSR
register
Z = 1
MOVLW
Move literal to W
NOP
No Operation
Syntax:
[ label ]
Syntax:
[ label ]
Operands:
0  k  255
Operands:
None
Operation:
k  (W)
Operation:
No operation
Status Affected:
None
Status Affected:
None
Description:
The eight-bit literal ‘k’ is loaded into
W register. The “don’t cares” will
assemble as ‘0’s.
Description:
No operation.
Words:
1
Cycles:
1
Words:
1
Cycles:
1
Example:
MOVLW k
Example:
MOVLW
NOP
0x5A
After Instruction
W =
DS41430A-page 178
NOP
0x5A
 2010 Microchip Technology Inc.
PIC16F/LF720/721
RETFIE
Return from Interrupt
RETLW
Return with literal in W
Syntax:
[ label ]
Syntax:
[ label ]
Operands:
None
Operands:
0  k  255
Operation:
TOS  PC,
1  GIE
Operation:
k  (W);
TOS  PC
Status Affected:
None
Status Affected:
None
Description:
Return from Interrupt. Stack is
POPed and Top-of-Stack (TOS) is
loaded in the PC. Interrupts are
enabled by setting Global
Interrupt Enable bit, GIE
(INTCON<7>). This is a two-cycle
instruction.
Description:
The W register is loaded with the
eight bit literal ‘k’. The program
counter is loaded from the top of
the stack (the return address).
This is a two-cycle instruction.
Words:
1
Cycles:
2
Example:
RETFIE
Words:
1
Cycles:
2
Example:
RETFIE
After Interrupt
PC =
GIE =
TABLE
TOS
1
RETLW k
CALL TABLE;W contains
table
;offset value
•
;W now has table value
•
•
ADDWF PC ;W = offset
RETLW k1 ;Begin table
RETLW k2 ;
•
•
•
RETLW kn ; End of table
Before Instruction
W = 0x07
After Instruction
W = value of k8
RETURN
 2010 Microchip Technology Inc.
Return from Subroutine
Syntax:
[ label ]
Operands:
None
RETURN
Operation:
TOS  PC
Status Affected:
None
Description:
Return from subroutine. The stack
is POPed and the top of the stack
(TOS) is loaded into the program
counter. This is a two-cycle
instruction.
DS41430A-page 179
PIC16F/LF720/721
RLF
Rotate Left f through Carry
SLEEP
Enter Sleep mode
Syntax:
[ label ]
Syntax:
[ label ] SLEEP
Operands:
0  f  127
d  [0,1]
Operands:
None
Operation:
Operation:
See description below
Status Affected:
C
Description:
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 the W register.
If ‘d’ is ‘1’, the result is stored
back in register ‘f’.
00h  WDT,
0  WDT prescaler,
1  TO,
0  PD
RLF
f,d
C
Words:
1
Cycles:
1
Example:
Status Affected:
TO, PD
Description:
The power-down Status bit, PD is
cleared. Time-out Status bit, TO
is set. Watchdog Timer and its
prescaler are cleared.
The processor is put into Sleep
mode with the oscillator stopped.
Register f
RLF
REG1,0
Before Instruction
REG1
C
=
=
1110 0110
0
=
=
=
1110 0110
1100 1100
1
After Instruction
REG1
W
C
RRF
Rotate Right f through Carry
SUBLW
Syntax:
[ label ]
Syntax:
[ label ] SUBLW k
Operands:
0  f  127
d  [0,1]
Operands:
0 k 255
Operation:
k - (W) W)
Operation:
See description below
Status Affected: C, DC, Z
Status Affected:
C
Description:
Description:
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 the W register.
If ‘d’ is ‘1’, the result is placed
back in register ‘f’.
RRF f,d
C
DS41430A-page 180
Register f
Subtract W from literal
The W register is subtracted (2’s
complement method) from the
eight-bit literal ‘k’. The result is
placed in the W register.
C=0
Wk
C=1
Wk
DC = 0
W<3:0>  k<3:0>
DC = 1
W<3:0>  k<3:0>
 2010 Microchip Technology Inc.
PIC16F/LF720/721
SUBWF
Subtract W from f
XORLW
Exclusive OR literal with W
Syntax:
[ label ] SUBWF f,d
Syntax:
[ label ] XORLW k
Operands:
0 f 127
d  [0,1]
Operands:
0 k 255
(f) - (W) destination)
Operation:
(W) .XOR. k W)
Operation:
Status Affected: C, DC, Z
Description:
SWAPF
Status Affected:
Z
Description:
The contents of the W register
are XOR’ed with the eight-bit
literal ‘k’. The result is placed in
the W register.
Subtract (2’s complement method)
W register from register ‘f’. If ‘d’ is
‘0’, the result is stored in the W
register. If ‘d’ is ‘1’, the result is
stored back in register ‘f.
C=0
Wf
C=1
Wf
DC = 0
W<3:0>  f<3:0>
DC = 1
W<3:0>  f<3:0>
Swap Nibbles in f
XORWF
Exclusive OR W with f
Syntax:
[ label ] SWAPF f,d
Syntax:
[ label ] XORWF
Operands:
0  f  127
d  [0,1]
Operands:
0  f  127
d  [0,1]
Operation:
(f<3:0>)  (destination<7:4>),
(f<7:4>)  (destination<3:0>)
Operation:
(W) .XOR. (f) destination)
Status Affected:
Z
Status Affected:
None
Description:
Description:
The upper and lower nibbles of
register ‘f’ are exchanged. If ‘d’ is
‘0’, the result is placed in the W
register. If ‘d’ is ‘1’, the result is
placed in register ‘f’.
Exclusive OR the contents of the
W register with register ‘f’. If ‘d’ is
‘0’, the result is stored in the W
register. If ‘d’ is ‘1’, the result is
stored back in register ‘f’.
 2010 Microchip Technology Inc.
f,d
DS41430A-page 181
PIC16F/LF720/721
NOTES:
DS41430A-page 182
 2010 Microchip Technology Inc.
PIC16F/LF720/721
1.0
DEVELOPMENT SUPPORT
The PIC® microcontrollers and dsPIC® digital signal
controllers are supported with a full range of software
and hardware development tools:
• Integrated Development Environment
- MPLAB® IDE Software
• Compilers/Assemblers/Linkers
- MPLAB C Compiler for Various Device
Families
- HI-TECH C for Various Device Families
- MPASMTM Assembler
- MPLINKTM Object Linker/
MPLIBTM Object Librarian
- MPLAB Assembler/Linker/Librarian for
Various Device Families
• Simulators
- MPLAB SIM Software Simulator
• Emulators
- MPLAB REAL ICE™ In-Circuit Emulator
• In-Circuit Debuggers
- MPLAB ICD 3
- PICkit™ 3 Debug Express
• Device Programmers
- PICkit™ 2 Programmer
- MPLAB PM3 Device Programmer
• Low-Cost Demonstration/Development Boards,
Evaluation Kits, and Starter Kits
1.1
MPLAB Integrated Development
Environment Software
The MPLAB IDE software brings an ease of software
development previously unseen in the 8/16/32-bit
microcontroller market. The MPLAB IDE is a Windows®
operating system-based application that contains:
• A single graphical interface to all debugging tools
- Simulator
- Programmer (sold separately)
- In-Circuit Emulator (sold separately)
- In-Circuit Debugger (sold separately)
• A full-featured editor with color-coded context
• A multiple project manager
• Customizable data windows with direct edit of
contents
• High-level source code debugging
• Mouse over variable inspection
• Drag and drop variables from source to watch
windows
• Extensive on-line help
• Integration of select third party tools, such as
IAR C Compilers
The MPLAB IDE allows you to:
• Edit your source files (either C or assembly)
• One-touch compile or assemble, and download to
emulator and simulator tools (automatically
updates all project information)
• Debug using:
- Source files (C or assembly)
- Mixed C and assembly
- Machine code
MPLAB IDE supports multiple debugging tools in a
single development paradigm, from the cost-effective
simulators, through low-cost in-circuit debuggers, to
full-featured emulators. This eliminates the learning
curve when upgrading to tools with increased flexibility
and power.
 2010 Microchip Technology Inc.
DS41430A-page 183
PIC16F/LF720/721
1.2
MPLAB C Compilers for Various
Device Families
The MPLAB C Compiler code development systems
are complete ANSI C compilers for Microchip’s PIC18,
PIC24 and PIC32 families of microcontrollers and the
dsPIC30 and dsPIC33 families of digital signal controllers. These compilers provide powerful integration
capabilities, superior code optimization and ease of
use.
For easy source level debugging, the compilers provide
symbol information that is optimized to the MPLAB IDE
debugger.
1.3
HI-TECH C for Various Device
Families
The HI-TECH C Compiler code development systems
are complete ANSI C compilers for Microchip’s PIC
family of microcontrollers and the dsPIC family of digital
signal controllers. These compilers provide powerful
integration capabilities, omniscient code generation
and ease of use.
For easy source level debugging, the compilers provide
symbol information that is optimized to the MPLAB IDE
debugger.
The compilers include a macro assembler, linker, preprocessor, and one-step driver, and can run on multiple
platforms.
1.4
MPASM Assembler
The MPASM Assembler is a full-featured, universal
macro assembler for PIC10/12/16/18 MCUs.
The MPASM Assembler generates relocatable object
files for the MPLINK Object Linker, Intel® standard HEX
files, MAP files to detail memory usage and symbol
reference, absolute LST files that contain source lines
and generated machine code and COFF files for
debugging.
The MPASM Assembler features include:
1.5
MPLINK Object Linker/
MPLIB Object Librarian
The MPLINK Object Linker combines relocatable
objects created by the MPASM Assembler and the
MPLAB C18 C Compiler. It can link relocatable objects
from precompiled libraries, using directives from a
linker script.
The MPLIB Object Librarian manages the creation and
modification of library files of precompiled code. When
a routine from a library is called from a source file, only
the modules that contain that routine will be linked in
with the application. This allows large libraries to be
used efficiently in many different applications.
The object linker/library features include:
• Efficient linking of single libraries instead of many
smaller files
• Enhanced code maintainability by grouping
related modules together
• Flexible creation of libraries with easy module
listing, replacement, deletion and extraction
1.6
MPLAB Assembler, Linker and
Librarian for Various Device
Families
MPLAB Assembler produces relocatable machine
code from symbolic assembly language for PIC24,
PIC32 and dsPIC devices. MPLAB C Compiler uses
the assembler to produce its object file. The assembler
generates relocatable object files that can then be
archived or linked with other relocatable object files and
archives to create an executable file. Notable features
of the assembler include:
•
•
•
•
•
•
Support for the entire device instruction set
Support for fixed-point and floating-point data
Command line interface
Rich directive set
Flexible macro language
MPLAB IDE compatibility
• Integration into MPLAB IDE projects
• User-defined macros to streamline
assembly code
• Conditional assembly for multi-purpose
source files
• Directives that allow complete control over the
assembly process
DS41430A-page 184
 2010 Microchip Technology Inc.
PIC16F/LF720/721
1.7
MPLAB SIM Software Simulator
The MPLAB SIM Software Simulator allows code
development in a PC-hosted environment by simulating the PIC MCUs and dsPIC® DSCs on an instruction
level. On any given instruction, the data areas can be
examined or modified and stimuli can be applied from
a comprehensive stimulus controller. Registers can be
logged to files for further run-time analysis. The trace
buffer and logic analyzer display extend the power of
the simulator to record and track program execution,
actions on I/O, most peripherals and internal registers.
The MPLAB SIM Software Simulator fully supports
symbolic debugging using the MPLAB C Compilers,
and the MPASM and MPLAB Assemblers. The software simulator offers the flexibility to develop and
debug code outside of the hardware laboratory environment, making it an excellent, economical software
development tool.
1.8
MPLAB REAL ICE In-Circuit
Emulator System
MPLAB REAL ICE In-Circuit Emulator System is
Microchip’s next generation high-speed emulator for
Microchip Flash DSC and MCU devices. It debugs and
programs PIC® Flash MCUs and dsPIC® Flash DSCs
with the easy-to-use, powerful graphical user interface of
the MPLAB Integrated Development Environment (IDE),
included with each kit.
The emulator is connected to the design engineer’s PC
using a high-speed USB 2.0 interface and is connected
to the target with either a connector compatible with incircuit debugger systems (RJ11) or with the new highspeed, noise tolerant, Low-Voltage Differential Signal
(LVDS) interconnection (CAT5).
The emulator is field upgradable through future firmware
downloads in MPLAB IDE. In upcoming releases of
MPLAB IDE, new devices will be supported, and new
features will be added. MPLAB REAL ICE offers
significant advantages over competitive emulators
including low-cost, full-speed emulation, run-time
variable watches, trace analysis, complex breakpoints, a
ruggedized probe interface and long (up to three meters)
interconnection cables.
 2010 Microchip Technology Inc.
1.9
MPLAB ICD 3 In-Circuit Debugger
System
MPLAB ICD 3 In-Circuit Debugger System is Microchip's most cost effective high-speed hardware
debugger/programmer for Microchip Flash Digital Signal Controller (DSC) and microcontroller (MCU)
devices. It debugs and programs PIC® Flash microcontrollers and dsPIC® DSCs with the powerful, yet easyto-use graphical user interface of MPLAB Integrated
Development Environment (IDE).
The MPLAB ICD 3 In-Circuit Debugger probe is connected to the design engineer's PC using a high-speed
USB 2.0 interface and is connected to the target with a
connector compatible with the MPLAB ICD 2 or MPLAB
REAL ICE systems (RJ-11). MPLAB ICD 3 supports all
MPLAB ICD 2 headers.
1.10
PICkit 3 In-Circuit Debugger/
Programmer and
PICkit 3 Debug Express
The MPLAB PICkit 3 allows debugging and programming of PIC® and dsPIC® Flash microcontrollers at a
most affordable price point using the powerful graphical
user interface of the MPLAB Integrated Development
Environment (IDE). The MPLAB PICkit 3 is connected
to the design engineer's PC using a full speed USB
interface and can be connected to the target via an
Microchip debug (RJ-11) connector (compatible with
MPLAB ICD 3 and MPLAB REAL ICE). The connector
uses two device I/O pins and the reset line to implement in-circuit debugging and In-Circuit Serial Programming™.
The PICkit 3 Debug Express include the PICkit 3, demo
board and microcontroller, hookup cables and CDROM
with user’s guide, lessons, tutorial, compiler and
MPLAB IDE software.
DS41430A-page 185
PIC16F/LF720/721
1.11
PICkit 2 Development
Programmer/Debugger and
PICkit 2 Debug Express
The PICkit™ 2 Development Programmer/Debugger is
a low-cost development tool with an easy to use interface for programming and debugging Microchip’s Flash
families of microcontrollers. The full featured
Windows® programming interface supports baseline
(PIC10F,
PIC12F5xx,
PIC16F5xx),
midrange
(PIC12F6xx, PIC16F), PIC18F, PIC24, dsPIC30,
dsPIC33, and PIC32 families of 8-bit, 16-bit, and 32-bit
microcontrollers, and many Microchip Serial EEPROM
products. With Microchip’s powerful MPLAB Integrated
Development Environment (IDE) the PICkit™ 2
enables in-circuit debugging on most PIC® microcontrollers. In-Circuit-Debugging runs, halts and single
steps the program while the PIC microcontroller is
embedded in the application. When halted at a breakpoint, the file registers can be examined and modified.
The PICkit 2 Debug Express include the PICkit 2, demo
board and microcontroller, hookup cables and CDROM
with user’s guide, lessons, tutorial, compiler and
MPLAB IDE software.
1.12
MPLAB PM3 Device Programmer
The MPLAB PM3 Device Programmer is a universal,
CE compliant device programmer with programmable
voltage verification at VDDMIN and VDDMAX for
maximum reliability. It features a large LCD display
(128 x 64) for menus and error messages and a modular, detachable socket assembly to support various
package types. The ICSP™ cable assembly is included
as a standard item. In Stand-Alone mode, the MPLAB
PM3 Device Programmer can read, verify and program
PIC devices without a PC connection. It can also set
code protection in this mode. The MPLAB PM3
connects to the host PC via an RS-232 or USB cable.
The MPLAB PM3 has high-speed communications and
optimized algorithms for quick programming of large
memory devices and incorporates an MMC card for file
storage and data applications.
DS41430A-page 186
1.13
Demonstration/Development
Boards, Evaluation Kits, and
Starter Kits
A wide variety of demonstration, development and
evaluation boards for various PIC MCUs and dsPIC
DSCs allows quick application development on fully functional systems. Most boards include prototyping areas for
adding custom circuitry and provide application firmware
and source code for examination and modification.
The boards support a variety of features, including LEDs,
temperature sensors, switches, speakers, RS-232
interfaces, LCD displays, potentiometers and additional
EEPROM memory.
The demonstration and development boards can be
used in teaching environments, for prototyping custom
circuits and for learning about various microcontroller
applications.
In addition to the PICDEM™ and dsPICDEM™ demonstration/development board series of circuits, Microchip
has a line of evaluation kits and demonstration software
for analog filter design, KEELOQ® security ICs, CAN,
IrDA®, PowerSmart battery management, SEEVAL®
evaluation system, Sigma-Delta ADC, flow rate
sensing, plus many more.
Also available are starter kits that contain everything
needed to experience the specified device. This usually
includes a single application and debug capability, all
on one board.
Check the Microchip web page (www.microchip.com)
for the complete list of demonstration, development
and evaluation kits.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
23.0
ELECTRICAL SPECIFICATIONS
Absolute Maximum Ratings(†)
Ambient temperature under bias....................................................................................................... -40°C to +125°C
Storage temperature ........................................................................................................................ -65°C to +150°C
Voltage on VDD with respect to VSS, PIC16F720/721 ........................................................................ -0.3V to +6.5V
Voltage on VDD with respect to VSS, PIC16LF720/721 ...................................................................... -0.3V to +4.0V
Voltage on MCLR with respect to Vss ................................................................................................. -0.3V to +9.0V
Voltage on all other pins with respect to VSS ........................................................................... -0.3V to (VDD + 0.3V)
Total power dissipation(1) ............................................................................................................................... 800 mW
Maximum current out of VSS pin ...................................................................................................................... 95 mA
Maximum current into VDD pin ......................................................................................................................... 70 mA
Clamp current, IK (VPIN < 0 or VPIN > VDD)20 mA
Maximum output current sunk by any I/O pin.................................................................................................... 25 mA
Maximum output current sourced by any I/O pin .............................................................................................. 25 mA
Maximum current sunk by all ports, -40°C  TA  +85°C for industrial............................................................ 200 mA
Maximum current sunk by all ports, -40°C  TA  +125°C for extended ........................................................... 90 mA
Maximum current sourced by all ports, 40°C  TA  +85°C for industrial....................................................... 140 mA
Maximum current sourced by all ports, -40°C  TA  +125°C for extended ...................................................... 65 mA
Note 1:
Power dissipation is calculated as follows: PDIS = VDD x {IDD –  IOH} +  {(VDD – VOH) x IOH} + (VOl x IOL).
† 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 above maximum rating conditions for
extended periods may affect device reliability.
 2010 Microchip Technology Inc.
DS41430A-page 187
PIC16F/LF720/721
23.1
DC Characteristics: PIC16F/LF720/721-I/E (Industrial, Extended)
PIC16LF720/721
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +85°C for industrial
-40°C  TA  +125°C for extended
PIC16F720/721
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
Sym.
VDD
Characteristic
Min.
Typ†
Max.
Units
Conditions
Supply Voltage
PIC16LF720/721
1.8
—
3.6
V
FOSC  16 MHz: HFINTOSC, EC
D001
PIC16F720/721
1.8
—
5.5
V
FOSC  16 MHz: HFINTOSC, EC
D002*
Voltage(1)
PIC16LF720/721
1.5
—
—
V
Device in Sleep mode
PIC16F720/721
1.7
—
—
V
Device in Sleep mode
—
1.6
—
V
PIC16LF720/721
—
0.8
—
V
Device in Sleep mode
PIC16F720/721
—
1.5
—
V
Device in Sleep mode
-5.5
-5.5
-5.5
—
—
—
5.5
5.5
5.5
%
%
%
VFVR = 1.024V, VDD  2.5V
VFVR = 2.048V, VDD  2.5V
VFVR = 4.096V, VDD 4.75V;
-40 TA85°C
-6
-6
-6
—
—
—
6
6
6
%
%
%
VFVR = 1.024V, VDD  2.5V
VFVR = 2.048V, VDD  2.5V
VFVR = 4.096V, VDD 4.75V;
-40 TA125°C
0.05
—
—
V/ms
VDR
RAM Data Retention
D002*
D003
VPOR*
Power-on Reset Release Voltage
VPORR*
Power-on Reset Rearm Voltage
VFVR
D004*
SVDD
Fixed Voltage Reference Voltage,
Initial Accuracy
VDD Rise Rate to ensure internal
Power-on Reset signal
See Section 3.2 “Power-on Reset
(POR)” for details.
*
†
These parameters are characterized but not tested.
Data in “Typ” column is at 3.3V, 25°C unless otherwise stated. These parameters are for design guidance only and are
not tested.
Note 1: This is the limit to which VDD can be lowered in Sleep mode without losing RAM data.
DS41430A-page 188
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 23-1:
POR AND POR REARM WITH SLOW RISING VDD
VDD
VPOR
VPORR
VSS
NPOR
POR REARM
VSS
TVLOW(2)
Note 1:
2:
3:
TPOR(3)
When NPOR is low, the device is held in Reset.
TPOR 1 s typical.
TVLOW 2.7 s typical.
 2010 Microchip Technology Inc.
DS41430A-page 189
PIC16F/LF720/721
23.2
DC Characteristics: PIC16F/LF720/721-I/E (Industrial, Extended)
PIC16LF720/721
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +85°C for industrial
-40°C  TA  +125°C for extended
PIC16F720/721
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +85°C for industrial
-40°C  TA  +125°C for extended
Param
No.
Conditions
Device
Characteristics
Min.
Typ†
Max.
Units
VDD
Note
Supply Current (IDD)(1, 2)
D013
D013
Supply Current (IDD)
D014
D014
D015
D015
—
125
180
A
1.8
—
230
270
A
3.0
—
150
205
A
1.8
—
225
320
A
3.0
—
250
410
A
5.0
—
290
330
A
1.8
—
460
500
A
3.0
—
300
430
A
1.8
—
450
655
A
3.0
—
500
730
A
5.0
—
100
130
A
1.8
—
120
150
A
3.0
—
115
195
A
1.8
—
135
200
A
3.0
—
150
220
A
5.0
—
650
800
A
1.8
—
1000
1200
A
3.0
D016
—
625
850
A
1.8
—
1000
1200
A
3.0
—
1100
1500
A
5.0
—
1.0
1.2
mA
1.8
—
1.5
1.85
mA
3.0
—
1
1.2
mA
1.8
—
1.5
1.7
mA
3.0
—
1.7
2.1
mA
5.0
D017
Note 1:
2:
FOSC = 1 MHz
EC Oscillator mode
(1, 2)
D016
D017
FOSC = 1 MHz
EC Oscillator mode
FOSC = 4 MHz
EC Oscillator mode
FOSC = 4 MHz
EC Oscillator mode
FOSC = 500 kHz
MFINTOSC mode
FOSC = 500 kHz
MFINTOSC mode
FOSC = 8 MHz
HFINTOSC mode
FOSC = 8 MHz
HFINTOSC mode
FOSC = 16 MHz
HFINTOSC mode
FOSC = 16 MHz
HFINTOSC mode
The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from
rail-to-rail (except for INTOSC mode); all I/O pins tri-stated, pulled to VDD; MCLR = VDD; WDT disabled.
The supply current is mainly a function of the operating voltage and frequency. Other factors, such as I/O pin loading
and switching rate, oscillator type, internal code execution pattern and temperature, also have an impact on the current
consumption.
DS41430A-page 190
 2010 Microchip Technology Inc.
PIC16F/LF720/721
23.3
DC Characteristics: PIC16F/LF720/721-I/E (Power-Down)
PIC16LF720/721
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +85°C for industrial
-40°C  TA  +125°C for extended
PIC16F720/721
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 Characteristics
Power-down Base Current
Min.
Typ†
Conditions
Max.
+85°C
Max.
+125°C
Units
1
—
A
VDD
D020
—
0.02
—
0.08
2
—
A
3.0
D020
—
17
35
—
A
1.8
—
20
40
—
A
3.0
—
22
50
—
A
5.0
—
0.5
6
—
A
1.8
—
0.8
7
—
A
3.0
—
18
35
—
A
1.8
—
21
40
—
A
3.0
D021
D021
D021A
D021A
1.8
—
23
55
—
A
5.0
—
8.5
23
—
A
1.8
—
8.5
26
—
A
3.0
—
35
50
—
A
1.8
—
42
72
—
A
3.0
—
72
120
—
A
5.0
D022
—
—
—
—
A
1.8
—
7.5
12
—
A
3.0
D022
—
—
—
—
A
1.8
—
36
59
—
A
3.0
—
70
100
—
A
5.0
Power-down Base Current (IPD)
D027
D027
D027A
D027A
†
Note 1:
2:
3:
4:
Note
(IPD)(2)
WDT, BOR, FVR, and all
Peripherals Inactive
WDT, BOR, FVR, and all
Peripherals Inactive
LPWDT Current (Note 1)
LPWDT Current (Note 1)
FVR current (Note 1. Note 3)
FVR current (Note 1, Note 3)
BOR Current (Note 1, Note 3)
BOR Current (Note 1, Note 3)
(2)
—
0.06
0.7
—
A
1.8
—
0.08
1.0
—
A
3.0
—
16
36
—
A
1.8
—
21
24
—
A
3.0
—
25
54
—
A
5.0
—
250
400
—
A
1.8
—
250
400
—
A
3.0
—
280
430
—
A
1.8
—
280
430
—
A
3.0
—
280
430
—
A
5.0
A/D Current (Note 1, Note 4), no
conversion in progress
A/D Current (Note 1, Note 4), no
conversion in progress
A/D Current (Note 1, Note 4),
conversion in progress
A/D Current (Note 1, Note 4),
conversion in progress
Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are
not tested.
The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is
enabled. The peripheral  current can be determined by subtracting the base IDD or IPD current from this limit. Max
values should be used when calculating total current consumption.
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.
Fixed Voltage Reference is automatically enabled whenever the BOR is enabled.
A/D oscillator source is FRC.
 2010 Microchip Technology Inc.
DS41430A-page 191
PIC16F/LF720/721
23.4
DC Characteristics: PIC16F/LF720/721-I/E
DC CHARACTERISTICS
Param
No.
Sym.
VIL
Characteristic
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C  TA  +85°C for industrial
-40°C  TA  +125°C for extended
Min.
Typ†
Max.
Units
Conditions
Input Low Voltage
I/O PORT:
D030
—
—
0.8
V
4.5V  VDD  5.5V
—
—
0.15 VDD
V
1.8V  VDD  4.5V
with Schmitt Trigger buffer
—
—
0.2 VDD
V
2.0V  VDD  5.5V
with I2C™ levels
—
—
0.3 VDD
V
with TTL buffer
D030A
D031
D032
MCLR, OSC1 (RC mode)
—
—
0.2 VDD
V
D033A
OSC1 (HS mode)
—
—
0.3 VDD
V
—
—
2.0
—
—
V
4.5V  VDD 5.5V
0.25 VDD +
0.8
—
—
V
1.8V  VDD  4.5V
with Schmitt Trigger buffer
0.8 VDD
—
—
V
2.0V  VDD  5.5V
with I2C™ levels
0.7 VDD
—
—
V
VIH
Input High Voltage
I/O ports:
D040
with TTL buffer
D040A
D041
D042
MCLR
0.8 VDD
—
—
V
D043A
OSC1 (HS mode)
0.7 VDD
—
—
V
D043B
OSC1 (RC mode)
0.9 VDD
—
—
V
nA
IIL
Input Leakage Current(1)
D060
I/O ports
—
±5
± 125
±5
± 1000
nA
VSS  VPIN  VDD, Pin at highimpedance, 85°C
125°C
D061
MCLR(2)
MCLR(3)
—
—
± 50
±300
± 200
±1500
nA
nA
VSS  VPIN  VDD, 85°C
125°C
25
25
100
140
200
300
A
VDD = 3.3V, VPIN = VSS
VDD = 5.0V, VPIN = VSS
—
—
0.6
V
IOL = 8mA, VDD = 5V
IOL = 6mA, VDD = 3.3V
IOL = 1.8mA, VDD = 1.8V
VDD - 0.7
—
—
V
IOH = 3.5mA, VDD = 5V
IOH = 3mA, VDD = 3.3V
IOH = 1mA, VDD = 1.8V
—
—
50
pF
1k
10k
—
E/W
VMIN
—
—
V
IPUR
PORTB Weak Pull-up Current
D070*
VOL
D080
Output Low Voltage(3)
I/O ports
VOH
D090
Output High Voltage(3)
I/O ports
CIO
Capacitive Loading Specs on Output Pins
EP
Program Flash Memory
D101A*
All I/O pins
D130
Cell Endurance
D131
VDD for Read
Temperature during programming:
10°C  TA  40°C
Legend:
TBD = To Be Determined
* These parameters are characterized but not tested.
† Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are
not tested.
Note 1: Negative current is defined as current sourced by the pin.
2: 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.
3: Including OSC2 in CLKOUT mode.
DS41430A-page 192
 2010 Microchip Technology Inc.
PIC16F/LF720/721
23.4
DC Characteristics: PIC16F/LF720/721-I/E (Continued)
DC CHARACTERISTICS
Param
No.
Sym.
Characteristic
Min.
Typ†
Max.
Units
Conditions
8.0
—
9.0
V
Temperature during programming:
10°C  TA  40°C
2
2
—
—
5.5
3.6
V
V
PIC16F720/21
PIC16LF720/21
IPPPGM* Current on MCLR/VPP during
Erase/Write
—
—
5.0
mA
Temperature during programming:
10°C  TA  40°C
IDDPGM* Current on VDD during Erase/
Write
—
5.0
mA
Temperature during programming:
10°C  TA  40°C
2.8
ms
Temperature during programming:
10°C  TA  40°C
—
Year
Voltage on MCLR/VPP during
Erase/Program
D132
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C  TA  +85°C for industrial
-40°C  TA  +125°C for extended
VPEW
VDD for Write or Row Erase
D133
TPEW
Erase/Write cycle time
—
D134*
TRETD
Characteristic Retention
40
—
Provided no other specifications
are violated
Legend:
TBD = To Be Determined
* These parameters are characterized but not tested.
† Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are
not tested.
Note 1: Negative current is defined as current sourced by the pin.
2: 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.
3: Including OSC2 in CLKOUT mode.
 2010 Microchip Technology Inc.
DS41430A-page 193
PIC16F/LF720/721
23.5
Thermal Considerations
Standard Operating Conditions (unless otherwise stated)
Operating temperature-40°C  TA  +125°C
Param
No.
Sym.
Characteristic
TH01
JA
Thermal Resistance Junction to
Ambient
TH02
JC
Thermal Resistance Junction to
Case
TH03
TH04
TH05
TH06
TJMAX
PD
Maximum Junction Temperature
Power Dissipation
PINTERNAL Internal Power Dissipation
PI/O
I/O Power Dissipation
Typ.
Units
62.4
85.2
108.1
40
28.1
24.2
32.2
2.5
150
—
—
—
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C
W
W
W
Conditions
20-pin PDIP package
20-pin SOIC package
20-pin SSOP package
20-pin QFN 4x4mm package
20-pin PDIP package
20-pin SOIC package
20-pin SSOP package
20-pin QFN 4x4mm package
PD = PINTERNAL + PI/O
PINTERNAL = IDD x VDD(1)
PI/O =  (IOL * VOL) +  (IOH * (VDD VOH))
TH07
PDER
Derated Power
—
W
PDER = PDMAX (TJ - TA)/JA(2)
Note 1: IDD is current to run the chip alone without driving any load on the output pins.
2: TA = Ambient Temperature
3: TJ = Junction Temperature
DS41430A-page 194
 2010 Microchip Technology Inc.
PIC16F/LF720/721
23.6
Timing Parameter Symbology
The timing parameter symbols have been created with
one of the following formats:
1. TppS2ppS
2. TppS
T
F
Frequency
Lowercase letters (pp) and their meanings:
pp
cc
CCP1
ck
CLKOUT
cs
CS
di
SDI
do
SDO
dt
Data in
io
I/O PORT
mc
MCLR
Uppercase letters and their meanings:
S
F
Fall
H
High
I
Invalid (High-impedance)
L
Low
FIGURE 23-2:
T
Time
osc
rd
rw
sc
ss
t0
t1
wr
OSC1
RD
RD or WR
SCK
SS
T0CKI
T1CKI
WR
P
R
V
Z
Period
Rise
Valid
High-impedance
LOAD CONDITIONS
Load Condition
Pin
CL
VSS
Legend: CL = 50 pF for all pins, 15 pF for
OSC2 output
 2010 Microchip Technology Inc.
DS41430A-page 195
PIC16F/LF720/721
23.7
AC Characteristics: PIC16F720/721-I/E
FIGURE 23-3:
CLOCK TIMING
Q4
Q1
Q2
Q3
Q4
Q1
OSC1/CLKIN
OS02
OS04
OS04
OS03
OSC2/CLKOUT
(CLKOUT Mode)
PIC16F720/721 VOLTAGE FREQUENCY GRAPH, -40°C  TA +125°C
FIGURE 23-4:
VDD (V)
5.5
3.6
2.5
2.3
2.0
1.8
0
4
10
16
Frequency (MHz)
Note 1: The shaded region indicates the permissible combinations of voltage and frequency.
DS41430A-page 196
 2010 Microchip Technology Inc.
PIC16F/LF720/721
PIC16LF720/721 VOLTAGE FREQUENCY GRAPH, -40°C  TA +125°C
VDD (V)
FIGURE 23-5:
3.6
2.5
2.3
2.0
1.8
0
4
16
10
Frequency (MHz)
Note 1: The shaded region indicates the permissible combinations of voltage and frequency.
HFINTOSC FREQUENCY ACCURACY OVER DEVICE VDD AND TEMPERATURE
FIGURE 23-6:
125
+ 5%
Temperature (°C)
85
± 3%
60
± 2%
25
0
-20
+ 5%
-40
1.8
2.0
2.5
3.0 3.3(2) 3.5
4.0
4.5
5.0
5.5
VDD (V)
Note 1: This chart covers both regulator enabled and regulator disabled states.
2: Regulator Nominal voltage.
 2010 Microchip Technology Inc.
DS41430A-page 197
PIC16F/LF720/721
TABLE 23-1:
CLOCK OSCILLATOR TIMING REQUIREMENTS
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C  TA  +125°C
Param
No.
OS01
Sym.
FOSC
Characteristic
Min.
Typ†
Max.
Units
DC
—
16
MHz
External CLKIN Frequency(1)
(1)
OS02
TOSC
External CLKIN Period
OS03
TCY
Instruction Cycle Time(1)
Conditions
EC Oscillator mode
63
—

ns
EC Oscillator mode
250
TCY
DC
ns
TCY = 4/FOSC
*
†
These parameters are characterized but not tested.
Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are
not tested.
Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. 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 CLKIN pin. When an
external clock input is used, the “max” cycle time limit is “DC” (no clock) for all devices.
TABLE 23-2:
OSCILLATOR PARAMETERS(1)
Standard Operating Conditions (unless otherwise stated)
Operating Temperature -40°C TA +125°C
Param
No.
OS08
OS08
Sym
HFOSC
MFOSC
Characteristic
Internal Calibrated HFINTOSC
Frequency(2, 3)
Internal Calibrated MFINTOSC
Frequency(2, 3)
OS10* TIOSC ST HFINTOSC 16 MHz and
500 kHz
Oscillator Wake-up from Sleep
Start-up Time
Freq
Tolerance
Min
Typ†
2%
—
16.0
—
MHz 0°C  TA  +85°C,
VDD 2.5V
3%
—
16.0
—
MHz +60°C  TA  +85°C,
VDD 2.5V
5%
—
16.0
—
MHz -40°C  TA  +125°C,
VDD 2.5V
2%
—
500
—
kHz
0°C  TA  +85°C,
VDD 2.5V
3%
—
500
—
kHz
+60°C  TA  +85°C,
VDD 2.5V
5%
—
500
—
kHz
-40°C  TA  +125°C,
VDD 2.5V
—
—
5
8
s
Max Units
Conditions
*
†
These parameters are characterized but not tested.
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: 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 pin. When an external clock input is used,
the ‘max’ cycle time limit is ‘DC’ (no clock) for all devices.
2: To ensure these oscillator frequency tolerances, VDD and VSS must be capacitively decoupled as close to
the device as possible. 0.1 F and 0.01 F values in parallel are recommended.
3: The frequency tolerance of the internal oscillator is ±2% from 0-60°C and ±3% from 60-85°C (see
Figure 23-6).
DS41430A-page 198
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 23-7:
CLKOUT AND I/O TIMING
Cycle
Write
Fetch
Read
Execute
Q4
Q1
Q2
Q3
FOSC
OS12
OS11
OS20
OS21
CLKOUT
OS19
OS18
OS16
OS13
OS17
I/O pin
(Input)
OS14
OS15
I/O pin
(Output)
New Value
Old Value
OS18, OS19
TABLE 23-3:
CLKOUT AND I/O TIMING PARAMETERS
Standard Operating Conditions (unless otherwise stated)
Operating Temperature -40°C TA +125°C
Param
No.
Sym.
OS11* TOSH2CKL
Characteristic
FOSC to CLKOUT (1)
OS12* TOSH2CKH FOSC to CLKOUT
OS13* TCKL2IOV
(1)
CLKOUT to Port out
valid(1)
CLKOUT(1)
Min.
Typ†
Max.
Units
Conditions
—
—
70
ns
VDD = 3.3-5.0V
—
—
72
ns
VDD = 3.3-5.0V
—
—
20
ns
OS14* TIOV2CKH
Port input valid before
TOSC + 200 ns
—
—
ns
OS15* TOSH2IOV
FOSC (Q1 cycle) to Port out valid
—
50
70*
ns
VDD = 3.3-5.0V
OS16* TOSH2IOI
FOSC (Q2 cycle) to Port input invalid
(I/O in hold time)
50
—
—
ns
VDD = 3.3-5.0V
OS17* TIOV2OSH
Port input valid to FOSC(Q2 cycle)
(I/O in setup time)
20
—
—
ns
OS18* TIOR
Port output rise time(2)
—
—
15
40
32
72
ns
VDD = 2.0V
VDD = 3.3-5.0V
OS19* TIOF
Port output fall time(2)
—
—
28
15
55
30
ns
VDD = 2.0V
VDD = 3.3-5.0V
OS20* TINP
INT pin input high or low time
25
—
—
ns
OS21* TRBP
PORTB interrupt-on-change new input
level time
TCY
—
—
ns
*
†
Note 1:
2:
These parameters are characterized but not tested.
Data in “Typ” column is at 3.0V, 25C unless otherwise stated.
Measurements are taken in RC mode where CLKOUT output is 4 x TOSC.
Includes OSC2 in CLKOUT mode.
 2010 Microchip Technology Inc.
DS41430A-page 199
PIC16F/LF720/721
FIGURE 23-8:
BROWN-OUT RESET TIMING AND CHARACTERISTICS
VDD
VBOR + VHYST
VBOR
(Device not in Brown-out Reset)
(Device in Brown-out Reset)
TBORREJ
37
Reset
(due to BOR)
33(1)
Note 1: 64 ms delay only if PWRTE bit in the Configuration Word register is programmed to ‘0’. 2ms
delay if PWRTE = 0 and VREGEN = 1.
DS41430A-page 200
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 23-4:
RESET, WATCHDOG TIME, OSCILLATOR START-UP TIMER, POWER-UP TIMER,
AND BROWN-OUT RESET PARAMETERS
Standard Operating Conditions (unless otherwise stated)
Operating Temperature -40°C TA +125°C
Param
No.
Sym.
Characteristic
Min.
Typ†
Max. Units
Conditions
30*
TMCL
MCLR Pulse Width (low)
2
5
—
—
—
—
s
s
VDD = 5V, -40°C to +85°C
VDD = 5V(1)
31
TWDT
Standard Watchdog Timer Time-out
Period (No Prescaler)(2)
10
10
18
18
27
33
ms
ms
VDD = 3.3V-5V, -40°C to +85°C
VDD = 3.3V-5V(1)
33*
TPWRT
Power-up Timer Period, PWRTE = 0
40
65
140
ms
34*
TIOZ
I/O high-impedance from MCLR Low
or Watchdog Timer Reset
—
—
2.0
s
35
VBOR
Brown-out Reset Voltage
1.80
1.9
2.1
V
36*
VHYST
Brown-out Reset Hysteresis
0
25
50
mV
37*
TBORDC Brown-out Reset DC Response
Time
1
3
5
10
s
VDD  VBOR, -40°C to +85°C
VDD  VBOR
*
†
These parameters are characterized but not tested.
Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only
and are not tested.
Note 1: Voltages above 3.6V require that the regulator be enabled.
2: Design Target. If unable to meet this target, the maximum can be increased, but the minimum cannot be
changed.
FIGURE 23-9:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI
40
41
42
T1CKI
45
46
47
49
TMR0 or
TMR1
 2010 Microchip Technology Inc.
DS41430A-page 201
PIC16F/LF720/721
TABLE 23-5:
TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Standard Operating Conditions (unless otherwise stated)
Operating Temperature -40°C TA +125°C
Param
No.
Sym.
TT0H
40*
41*
Characteristic
Min.
Typ†
Max.
Units
No
Prescaler
0.5 TCY + 20
—
—
ns
With
Prescaler
10
—
—
ns
No
Prescaler
0.5 TCY + 20
—
—
ns
With
Prescaler
10
—
—
ns
Greater of:
20 or TCY + 40
N
—
—
ns
Synchronous, No
Prescaler
0.5 TCY + 20
—
—
ns
Synchronous, with
Prescaler
15
—
—
ns
T0CKI High Pulse
Width
TT0L
T0CKI Low Pulse
Width
42*
TT0P
T0CKI Period
45*
TT1H
T1CKI
High
Time
Asynchronous
46*
TT1L
47*
TT1P
49*
30
—
—
ns
0.5 TCY + 20
—
—
ns
Synchronous, with
Prescaler
15
—
—
ns
Asynchronous
30
—
—
ns
Synchronous
Greater of:
30 or TCY + 40
N
—
—
ns
Asynchronous
60
—
—
ns
2 TOSC
—
7 TOSC
—
T1CKI
Synchronous, No
Low Time Prescaler
T1CKI
Input
Period
TCKEZ Delay from External Clock Edge to
TMR1
Timer Increment
*
†
Conditions
N = prescale value
(2, 4, ..., 256)
N = prescale value
(1, 2, 4, 8)
Timers in Sync
mode
These parameters are characterized but not tested.
Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only
and are not tested.
FIGURE 23-10:
CAPTURE/COMPARE/PWM TIMINGS (CCP)
CCP
(Capture mode)
CC01
CC02
CC03
Note:
Refer to Figure 23-2 for load conditions.
DS41430A-page 202
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 23-6:
CAPTURE/COMPARE/PWM REQUIREMENTS (CCP)
Standard Operating Conditions (unless otherwise stated)
Operating Temperature -40°C  TA  +125°C
Param
Sym.
No.
CC01* TccL
Characteristic
CCP Input Low Time
CC02* TccH
CCP Input High Time
CC03* TccP
CCP Input Period
Min.
Max.
Units
No Prescaler
0.5TCY + 20
—
—
ns
With Prescaler
20
—
—
ns
No Prescaler
0.5TCY + 20
—
—
ns
20
—
—
ns
3TCY + 40
N
—
—
ns
With Prescaler
*
†
Typ†
Conditions
N = prescale value (1, 4 or 16)
These parameters are characterized but not tested.
Data in “Typ” column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are
not tested.
TABLE 23-7:
PIC16F720/721 A/D CONVERTER (ADC) CHARACTERISTICS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C  TA  +125°C
Param
Sym.
No.
Characteristic
Min.
Typ†
Max.
Units
—
—
8
bit
Conditions
AD01
NR
Resolution
AD02
EIL
Integral Error
—
—
±1.0
LSb
VDD = 3.0V
AD03
EDL
Differential Error
—
—
±1
LSb
No missing codes
VDD = 3.0V
AD04
EOFF Offset Error
—
—
±2.0
LSb
VDD = 3.0V
AD07
EGN
Gain Error
—
—
±1.5
LSb
VDD = 3.0V
AD07
VAIN
Full-Scale Range
VSS
—
VREF
V
AD08
ZAIN
Recommended Impedance of
Analog Voltage Source
—
—
50
k
*
†
Can go higher if external 0.01F capacitor is
present on input pin.
These parameters are characterized but not tested.
Data in “Typ” column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not
tested.
 2010 Microchip Technology Inc.
DS41430A-page 203
PIC16F/LF720/721
TABLE 23-8:
PIC16F720/721 A/D CONVERSION REQUIREMENTS
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C £ TA £ +125°C
Param
No.
Sym.
Characteristic
AD130* TAD
A/D Clock Period
A/D Internal RC Oscillator
Period
AD131
TCNV
Min.
Typ†
Max.
Units
1.0
—
9.0
S
VDD  2.0V(2)
4.0
—
16.0
S
VDD  2.0V(2)
1.0
2.0
6.0
S
—
10.5
—
TAD
Set GO/DONE bit to new data in A/D
Result register
2
—
S
VDD = 3.0V, EC or INTOSC Clock
mode(3)
(ADRC mode)
Conversion Time (not including
Acquisition Time)(1)
Acquisition Time
AD132* TACQ
Conditions
*
†
These parameters are characterized but not tested.
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: The ADRES register may be read on the following TCY cycle.
2: Setting of 16.0 s TAD not recommended for temperature > 85°C.
3: If ADRC mode is selected for use with VDD 2.0V, longer acquisition times will be required (see Section 9.3 “A/D Acquisition Requirements” )
FIGURE 23-11:
PIC16F720/721 A/D CONVERSION TIMING (NORMAL MODE)
BSF ADCON0, GO
AD134
1 TCY
(TOSC/2(1))
AD131
Q4
AD130
A/D CLK
7
A/D Data
6
5
4
3
OLD_DATA
ADRES
1
0
NEW_DATA
1 TCY
ADIF
GO
Sample
2
DONE
AD132
Sampling Stopped
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.
DS41430A-page 204
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 23-12:
PIC16F720/721 A/D CONVERSION TIMING (SLEEP MODE)
BSF ADCON0, GO
(TOSC/2 + TCY(1))
AD134
1 TCY
AD131
Q4
AD130
A/D CLK
7
A/D Data
6
5
4
3
2
1
0
NEW_DATA
OLD_DATA
ADRES
ADIF
1 TCY
GO
DONE
Sampling Stopped
AD132
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.
FIGURE 23-13:
USART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
CK
US121
US121
DT
US122
US120
Note:
TABLE 23-9:
Refer to Figure 23-2 for load conditions.
USART SYNCHRONOUS TRANSMISSION REQUIREMENTS
Standard Operating Conditions (unless otherwise stated)
Operating Temperature
-40°C TA +125°C
Param.
No.
Symbol
Characteristic
Min.
Max.
Units
US120* TCKH2DTV SYNC XMIT (Master and Slave)
Clock high to data-out valid
3.0-5.5V
—
80
ns
1.8-5.5V
—
100
ns
Clock out rise time and fall time
(Master mode)
3.0-5.5V
—
45
ns
1.8-5.5V
—
50
ns
Data-out rise time and fall time
3.0-5.5V
—
45
ns
1.8-5.5V
—
50
ns
US121* TCKRF
US122* TDTRF
Conditions
* These parameters are characterized but not tested.
 2010 Microchip Technology Inc.
DS41430A-page 205
PIC16F/LF720/721
FIGURE 23-14:
USART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
CK
US125
DT
US126
Note: Refer to Figure 23-2 for load conditions.
TABLE 23-10: USART SYNCHRONOUS RECEIVE REQUIREMENTS
Standard Operating Conditions (unless otherwise stated)
Operating Temperature
-40°C TA +125°C
Param.
No.
Symbol
Characteristic
Min.
Max.
Units
10
—
ns
15
—
ns
US125* TDTV2CKL SYNC RCV (Master and Slave)
Data-hold before CK  (DT hold time)
US126* TCKL2DTL
Data-hold after CK  (DT hold time)
Conditions
* These parameters are characterized but not tested.
FIGURE 23-15:
SPI MASTER MODE TIMING (CKE = 0, SMP = 0)
SS
SP70
SCK
(CKP = 0)
SP71
SP72
SP78
SP79
SP79
SP78
SCK
(CKP = 1)
SP80
bit 6 - - - - - -1
MSb
SDO
LSb
SP75, SP76
SDI
MSb In
bit 6 - - - -1
LSb In
SP74
SP73
Note 1:
Refer to Figure 23-2 for load conditions.
DS41430A-page 206
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 23-16:
SPI MASTER MODE TIMING (CKE = 1, SMP = 1)
SS
SP81
SCK
(CKP = 0)
SP71
SP72
SP79
SP73
SCK
(CKP = 1)
SP80
SP78
LSb
bit 6 - - - - - -1
MSb
SDO
SP75, SP76
SDI
MSb In
bit 6 - - - -1
LSb In
SP74
Note 1:
Refer to Figure 23-2 for load conditions.
FIGURE 23-17:
SPI SLAVE MODE TIMING (CKE = 0)
SS
SP70
SCK
(CKP = 0)
SP83
SP71
SP72
SP78
SP79
SP79
SP78
SCK
(CKP = 1)
SP80
MSb
SDO
bit 6 - - - - - -1
LSb
SP77
SP75, SP76
SDI
MSb In
bit 6 - - - -1
LSb In
SP74
SP73
Note 1:
Refer to Figure 23-2 for load conditions.
 2010 Microchip Technology Inc.
DS41430A-page 207
PIC16F/LF720/721
FIGURE 23-18:
SPI SLAVE MODE TIMING (CKE = 1)
SP82
SS
SP70
SP83
SCK
(CKP = 0)
SP71
SP72
SCK
(CKP = 1)
SP80
MSb
SDO
bit 6 - - - - - -1
LSb
SP77
SP75, SP76
SDI
MSb In
bit 6 - - - -1
LSb In
SP74
Note 1:
Refer to Figure 23-2 for load conditions.
DS41430A-page 208
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 23-11: SPI MODE REQUIREMENTS
Param
No.
Symbol
Characteristic
SP70* TSSL2SCH,
TSSL2SCL
SS to SCK or SCK input
Min.
Typ† Max. Units Conditions
TCY
—
—
ns
SP71* TSCH
SCK input high time (Slave mode)
TCY + 20
—
—
ns
SP72* TSCL
SCK input low time (Slave mode)
TCY + 20
—
—
ns
SP73* TDIV2SCH,
TDIV2SCL
Setup time of SDI data input to SCK edge
100
—
—
ns
SP74* TSCH2DIL,
TSCL2DIL
Hold time of SDI data input to SCK edge
100
—
—
ns
SP75* TDOR
SDO data output rise time
—
10
25
ns
SP76* TDOF
SDO data output fall time
3.0-5.5V
1.8-5.5V
—
25
50
ns
—
10
25
ns
SP77* TSSH2DOZ
SS to SDO output high-impedance
10
—
50
ns
SP78* TSCR
SCK output rise time
(Master mode)
—
10
25
ns
—
25
50
ns
SP79* TSCF
SCK output fall time (Master mode)
—
10
25
ns
SP80* TSCH2DOV,
TSCL2DOV
SDO data output valid after
SCK edge
3.0-5.5V
—
—
50
ns
1.8-5.5V
—
—
145
ns
SP81* TDOV2SCH,
TDOV2SCL
SDO data output setup to SCK edge
Tcy
—
—
ns
SP82* TSSL2DOV
SDO data output valid after SS edge
—
—
50
ns
SP83* TSCH2SSH,
TSCL2SSH
SS after SCK edge
1.5TCY +
40
—
—
ns
3.0-5.5V
1.8-5.5V
* These parameters are characterized but not tested.
† Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested.
FIGURE 23-19:
I2C™ BUS START/STOP BITS TIMING
SCL
SP93
SP91
SP90
SP92
SDA
Start
Condition
Note 1:
Stop
Condition
Refer to Figure 23-2 for load conditions.
 2010 Microchip Technology Inc.
DS41430A-page 209
PIC16F/LF720/721
TABLE 23-12: I2C™ BUS START/STOP BITS REQUIREMENTS
Param
No.
Symbol
SP90*
TSU:STA
SP91*
THD:STA
SP92*
TSU:STO
SP93
THD:STO Stop condition
Characteristic
Start condition
Typ
4700
—
Max. Units
—
Setup time
400 kHz mode
600
—
—
Start condition
100 kHz mode
4000
—
—
Hold time
400 kHz mode
600
—
—
Stop condition
100 kHz mode
4700
—
—
Setup time
Hold time
*
100 kHz mode
Min.
400 kHz mode
600
—
—
100 kHz mode
4000
—
—
400 kHz mode
600
—
—
Conditions
ns
Only relevant for Repeated
Start condition
ns
After this period, the first
clock pulse is generated
ns
ns
These parameters are characterized but not tested.
FIGURE 23-20:
I2C™ BUS DATA TIMING
SP103
SP100
SP102
SP101
SCL
SP90
SP106
SP107
SP92
SP91
SDA
In
SP110
SP109
SP109
SDA
Out
Note 1:
DS41430A-page 210
Refer to Figure 23-2 for load conditions.
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TABLE 23-13: I2C™ BUS DATA REQUIREMENTS
Param.
No.
100*
Symbol
THIGH
Characteristic
Clock high time
Min.
Max.
Units
Conditions
100 kHz mode
4.0
—
s
Device must operate at a
minimum of 1.5 MHz
400 kHz mode
0.6
—
s
Device must operate at a
minimum of 10 MHz
1.5TCY
—
100 kHz mode
4.7
—
s
Device must operate at a
minimum of 1.5 MHz
400 kHz mode
1.3
—
s
Device must operate at a
minimum of 10 MHz
SSP Module
101*
TLOW
Clock low time
SSP Module
102*
103*
90*
91*
106*
107*
92*
109*
110*
TR
TF
TSU:STA
THD:STA
THD:DAT
TSU:DAT
TSU:STO
TAA
TBUF
CB
*
Note 1:
2:
1.5TCY
—
—
1000
ns
20 +
0.1CB
300
ns
100 kHz mode
—
250
ns
400 kHz mode
20 +
0.1CB
250
ns
CB is specified to be from
10-400 pF
Only relevant for
Repeated Start condition
SDA and SCL rise
time
100 kHz mode
SDA and SCL fall
time
400 kHz mode
100 kHz mode
4.7
—
s
400 kHz mode
0.6
—
s
Start condition hold 100 kHz mode
time
400 kHz mode
4.0
—
s
0.6
—
s
Start condition
setup time
Data input hold
time
100 kHz mode
0
—
ns
400 kHz mode
0
0.9
s
Data input setup
time
100 kHz mode
250
—
ns
400 kHz mode
100
—
ns
Stop condition
setup time
Output valid from
clock
Bus free time
100 kHz mode
4.7
—
s
400 kHz mode
0.6
—
s
100 kHz mode
—
3500
ns
400 kHz mode
—
—
ns
100 kHz mode
4.7
—
s
400 kHz mode
1.3
—
s
—
400
pF
Bus capacitive loading
CB is specified to be from
10-400 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
These parameters are characterized but not tested.
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 (400 kHz) I2C bus device can be used in a Standard mode (100 kHz) I2C bus system, but the
requirement TSU:DAT 250 ns must then be met. This will automatically be the case if the device does not
stretch the low period of the SCL signal. If such a device does stretch the low period of the SCL signal, it
must output the next data bit to the SDA line TR max. + TSU:DAT = 1000 + 250 = 1250 ns (according to the
Standard mode I2C bus specification), before the SCL line is released.
 2010 Microchip Technology Inc.
DS41430A-page 211
PIC16F/LF720/721
NOTES:
DS41430A-page 212
 2010 Microchip Technology Inc.
PIC16F/LF720/721
24.0
DC AND AC CHARACTERISTICS GRAPHS AND CHARTS
FIGURE 24-1:
PIC16F720/721 MAXIMUM IDD vs. FOSC OVER VDD, INTOSC MODE
210
200
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
5V
190
180
3.6V
IDD (µA)
170
2.5V
160
150
1.8V
140
130
120
110
62.5 kHz
125 kHz
250 kHz
500 kHz
FOSC
FIGURE 24-2:
PIC16LF720/721 MAXIMUM IDD vs. FOSC OVER VDD, INTOSC MODE
170
160
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
3.6V
IDD (µA)
150
3V
2.5V
140
130
1.8V
120
110
100
62.5 KHz
125 KHz
250 KHz
500 KHz
FOSC
 2010 Microchip Technology Inc.
DS41430A-page 213
PIC16F/LF720/721
FIGURE 24-3:
PIC16F720/721 MAXIMUM IDD vs. FOSC OVER VDD, INTOSC MODE
2,000
1,800
5V
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
3.6V
1,600
2.5V
1,400
IDD (µA)
1,200
1.8V
1,000
800
600
400
200
0
2 MHz
4 MHz
8 MHz
16 MHz
FOSC
FIGURE 24-4:
PIC16LF720/721 MAXIMUM IDD vs. FOSC OVER VDD, INTOSC MODE
2,250
2,000
s
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
3.6V
1,750
3V
1,500
IDD (µA)
2.5V
1,250
1.8V
1,000
750
500
250
0
2 MHz
4 MHz
8 MHz
16 MHz
FOSC
DS41430A-page 214
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 24-5:
PIC16F720/721 TYPICAL IDD vs. FOSC OVER VDD, INTOSC MODE
160
150
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
5V
IDD (µA)
140
3.6V
130
2.5V
120
1.8V
110
100
90
80
62.5 kHz
125 kHz
250 kHz
500 kHz
FOSC
FIGURE 24-6:
PIC16LF720/721 TYPICAL IDD vs. FOSC OVER VDD, INTOSC MODE
140
130
3.6V
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
3V
120
2.5V
IDD (µA)
110
100
1.8V
90
80
70
62.5 kHz
125 kHz
250 kHz
500 kHz
FOSC
 2010 Microchip Technology Inc.
DS41430A-page 215
PIC16F/LF720/721
FIGURE 24-7:
PIC16F720/721 TYPICAL IDD vs. FOSC OVER VDD, INTOSC MODE
2,000
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
1,800
1,600
5V
3.6V
1,400
2.5V
IDD (µA)
1,200
1,000
1.8V
800
600
400
200
0
2 MHz
4 MHz
8 MHz
16 MHz
FOSC
FIGURE 24-8:
PIC16LF720/721 TYPICAL IDD vs. FOSC OVER VDD, INTOSC MODE
2,000
1,800
3.6V
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
1,600
3V
1,400
IDD (µA)
2.5V
1,200
1,000
1.8V
800
600
400
200
0
2 MHz
4 MHz
8 MHz
16 MHz
VDD (V)
DS41430A-page 216
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 24-9:
PIC16LF720/721 MAXIMUM BASE IPD vs. VDD
7
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
6
125°C
IPD (µA)
5
4
85°C
3
2
1
0
1.8V
2V
2.5V
3V
3.6V
VDD (V)
FIGURE 24-10:
PIC16LF720/721 TYPICAL BASE IPD vs. VDD
250
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
200
25°C
IPD (nA)
150
100
50
0
1.8V
2V
2.5V
3V
3.6V
VDD (V)
FIGURE 24-11:
 2010 Microchip Technology Inc.
DS41430A-page 217
PIC16F/LF720/721
FIGURE 24-12:
TTL INPUT THRESHOLD VIN vs. VDD OVER TEMPERATURE
18
16
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
Max. 85°C
14
12
IPD (µA)
10
Typ. 25°C
8
6
4
2
0
1.8V
2V
3V
3.6V
5V
5.5V
VDD (V)
FIGURE 24-13:
SCHMITT TRIGGER INPUT THRESHOLD VIN vs. VDD OVER TEMPERATURE
3.5
3.0
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
VIH Max. -40°C
2.5
VIN (V)
2.0
1.5
VIH Min. 125°C
1.0
0.5
0.0
1.8
3.6
5.5
VDD (V)
DS41430A-page 218
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 24-14:
SCHMITT TRIGGER INPUT THRESHOLD VIN vs. VDD OVER TEMPERATURE
3.0
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
2.5
VIL Max. -40°C
VIN (V)
2.0
1.5
1.0
VIL Min. 125°C
0.5
0.0
1.8
3.6
5.5
VDD (V)
FIGURE 24-15:
VOH vs. IOH OVER TEMPERATURE, VDD = 5.5V
5.6
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
5.5
VOH (V)
5.4
5.3
Max. -40°
Typ. 25°
5.2
Min. 125°
5.1
5
-0.2
-1.0
-1.8
-2.6
-3.4
-4.2
-5.0
IOH (mA)
 2010 Microchip Technology Inc.
DS41430A-page 219
PIC16F/LF720/721
FIGURE 24-16:
VOH vs. IOH OVER TEMPERATURE, VDD = 3.6V
3.8
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
3.6
3.4
VOH (V)
Max. -40°
3.2
Typ. 25°
3
Min. 125°
2.8
2.6
-0.2
-1.0
-1.8
-2.6
-3.4
-4.2
-5.0
IOH (mA)
FIGURE 24-17:
VOH vs. IOH OVER TEMPERATURE, VDD = 1.8V
2
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
1.8
1.6
Max. -40°
1.4
VOH (V)
1.2
Typ. 25°
1
0.8
0.6
Min. 125°
0.4
0.2
0
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
-1.8
-2.0
IOH (mA)
DS41430A-page 220
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 24-18:
VOL vs. IOL OVER TEMPERATURE, VDD = 5.5V
0.5
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
0.45
0.4
0.35
Max. 125°
VOL (V)
0.3
0.25
0.2
Typ. 25°
0.15
0.1
Min. -40°
0.05
0
5.0
6.0
7.0
8.0
9.0
10.0
IOL (mA)
FIGURE 24-19:
VOL vs. IOL OVER TEMPERATURE, VDD = 3.6
0.9
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
0.8
0.7
0.6
Max. 125°
VOL (V)
0.5
0.4
Typ. 25°
0.3
0.2
Min. -40°
0.1
0
4.0
5.0
 2010 Microchip Technology Inc.
6.0
7.0
IOL (mA)
8.0
9.0
10.0
DS41430A-page 221
PIC16F/LF720/721
FIGURE 24-20:
VOL vs. IOL OVER TEMPERATURE, VDD = 1.8V
1.2
1
Maximum: Mean + 3 (-40°C to 125°C)
Typical: Mean @25°C
Minimum: Mean - 3 (-40°C to 125°C)
0.8
VOL (V)
Max. 125°
0.6
0.4
0.2
Min. -40°
0
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
IOL (mA)
FIGURE 24-21:
PIC16F720/721 PWRT PERIOD
105
95
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
Max. -40°C
TIME (ms)
85
75
Typ. 25°C
65
Min. 125°C
55
45
1.8V
2V
2.2V
2.4V
3V
3.6V
4V
4.5V
5V
5.5V
VDD
DS41430A-page 222
 2010 Microchip Technology Inc.
PIC16F/LF720/721
FIGURE 24-22:
PIC16F720/721 WDT TIME-OUT PERIOD
24.00
22.00
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
Max. -40°C
20.00
TIME (ms)
18.00
Typ. 25°C
16.00
14.00
Min. 125°C
12.00
10.00
1.8V
2V
2.2V
2.4V
3V
3.6V
4V
4.5V
5V
VDD
FIGURE 24-23:
PIC16F720/721 A/D INTERNAL RC OSCILLATOR PERIOD
6.0
5.0
Typical: Statistical Mean @25°C
Maximum: Mean (Worst-Case Temp) + 3
(-40°C to 125°C)
Period (µs)
4.0
3.0
Max.
Min.
2.0
1.0
0.0
1.8V
3.6V
5.5V
VDD(V)
 2010 Microchip Technology Inc.
DS41430A-page 223
PIC16F/LF720/721
FIGURE 24-24:
TYPICAL FVR (X1 AND X2) VS. SUPPLY VOLTAGE (V) NORMALIZED AT 3.0V
1.5
Percent Change (%)
1
0.5
0
-0.5
-1
-1.5
1.8
2.5
3
3.6
4.2
5.5
Voltage
FIGURE 24-25:
TYPICAL FVR CHANGE VS. TEMPERATURE NORMALIZED AT 25°C
1.5
1
Percent Change (%)
0.5
0
-0.5
-1
-1.5
-2
-2.5
-3
-40
0
45
85
125
Temperature (°C)
DS41430A-page 224
 2010 Microchip Technology Inc.
PIC16F/LF720/721
25.0
PACKAGING INFORMATION
25.1
Package Marking Information
20-Lead PDIP
Example
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
YYWWNNN
Example
20-Lead QFN 4x4
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
PIC16F721
-I/ML e3
0810017
20-Lead SOIC
Example
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
YYWWNNN
20-Lead SSOP
Legend: XX...X
Y
YY
WW
NNN
e3
*
*
PIC16F720
-I/SO e3
0810017
Example
XXXXXXXXXXXX
XXXXXXXXXXXX
YYWWNNN
Note:
PIC16F721
-I/P e3
0810017
PIC16F720
-I/SS 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.
Standard PICmicro® device marking consists of Microchip part number, year code, week code and
traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check
with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP
price.
 2010 Microchip Technology Inc.
DS41430A-page 225
PIC16F/LF720/721
25.2
Package Details
The following sections give the technical details of the packages.
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DS41430A-page 226
 2010 Microchip Technology Inc.
PIC16F/LF720/721
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 2010 Microchip Technology Inc.
DS41430A-page 227
PIC16F/LF720/721
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DS41430A-page 228
 2010 Microchip Technology Inc.
PIC16F/LF720/721
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 2010 Microchip Technology Inc.
DS41430A-page 229
PIC16F/LF720/721
Note:
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http://www.microchip.com/packaging
DS41430A-page 230
 2010 Microchip Technology Inc.
PIC16F/LF720/721
/HDG3ODVWLF6KULQN6PDOO2XWOLQH66±PP%RG\>[email protected]
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 2010 Microchip Technology Inc.
DS41430A-page 231
PIC16F/LF720/721
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
DS41430A-page 232
 2010 Microchip Technology Inc.
PIC16F/LF720/721
APPENDIX A:
DATA SHEET
REVISION HISTORY
Revision A (September 2010)
Original release of this document.
APPENDIX B:
This shows a comparison of features in the migration
from another PIC® device, the PIC16F722, to the
PIC16F720 device.
B.1
PIC16F722 to PIC16F720
TABLE B-1:
FEATURE COMPARISON
Feature
PIC16F722
PIC16F720
Max. Operating Speed
20 MHz
20 MHz
2K
2K
Max. Program
Memory (Words)
Max. SRAM (Bytes)
128
128
A/D Resolution
8-bit
8-bit
Timers (8/16-bit)
2/1
2/1
Oscillator Modes
8
8
Brown-out Reset
Y
Y
Internal Pull-ups
RB<7:4>
RB<7:4>
Interrupt-on-change
RB<7:0>
RB<7:4>
0
0
Comparator
AUSART
Y
Y
Extended WDT
N
N
Software Control
Option of WDT/BOR
N
N
INTOSC Frequencies
500 kHz 16 MHz
500 kHz 16 MHz
N
N
Clock Switching
 2010 Microchip Technology Inc.
MIGRATING FROM
OTHER PIC®
DEVICES
Note:
This device has been designed to perform
to the parameters of its data sheet. It has
been tested to an electrical specification
designed to determine its conformance
with these parameters. Due to process differences in the manufacture of this device,
this device may have different performance characteristics than its earlier version. These differences may cause this
device to perform differently in your application than the earlier version of this
device.
Note:
The user should verify that the device
oscillator starts and performs as
expected. Adjusting the loading capacitor
values and/or the oscillator mode may be
required.
DS41430A-page 233
PIC16F/LF720/721
NOTES:
DS41430A-page 234
 2010 Microchip Technology Inc.
PIC16F/LF720/721
INDEX
A
B
A/D
BF bit ........................................................................ 147, 159
Block Diagrams
(CCP) Capture Mode Operation ............................... 110
ADC ............................................................................ 77
ADC Transfer Function............................................... 84
Analog Input Model..................................................... 84
AUSART Receive ..................................................... 120
AUSART Transmit .................................................... 119
CCP PWM ................................................................ 114
Clock Source .............................................................. 67
Compare................................................................... 112
Interrupt Logic............................................................. 37
MCLR Circuit .............................................................. 29
On-Chip Reset Circuit................................................. 27
RA0 Pins..................................................................... 51
RA1 Pins..................................................................... 52
RA2 Pin ...................................................................... 53
RA4 Pin ...................................................................... 54
RA5 Pin ................................................................ 54, 55
RB0 Pin ...................................................................... 59
RB3 Pin ...................................................................... 60
RC0 Pin ...................................................................... 64
RC5 Pin ...................................................................... 65
RC6 Pin ...................................................................... 65
RC7 Pin ...................................................................... 65
SPI Mode.................................................................. 140
SSP (I2C Mode)........................................................ 149
Timer1 ................................................ 95, 101, 102, 103
Timer2 ...................................................................... 107
TMR0/WDT Prescaler ................................................ 91
Brown-out Reset (BOR)...................................................... 31
Specifications ........................................................... 201
Timing and Characteristics ....................................... 200
Specifications.................................................... 203, 204
Absolute Maximum Ratings .............................................. 187
AC Characteristics
Industrial and Extended ............................................ 196
Load Conditions ........................................................ 195
ADC .................................................................................... 77
Acquisition Requirements ........................................... 83
Associated registers.................................................... 85
Block Diagram............................................................. 77
Calculating Acquisition Time....................................... 83
Channel Selection....................................................... 78
Configuration............................................................... 78
Configuring Interrupt ................................................... 80
Conversion Clock........................................................ 78
Conversion Procedure ................................................ 80
Internal Sampling Switch (RSS) Impedance................ 83
Interrupts..................................................................... 79
Operation .................................................................... 79
Operation During Sleep .............................................. 80
Port Configuration ....................................................... 78
Source Impedance...................................................... 83
Special Event Trigger.................................................. 80
ADCON0 Register......................................................... 17, 81
ADCON1 Register......................................................... 18, 82
Addressable Universal Synchronous Asynchronous
Receiver Transmitter (AUSART)............................... 119
ADRES Register ................................................................. 82
ADRESH Register............................................................... 17
Analog-to-Digital Converter. See ADC
ANSELA Register ............................................................... 49
ANSELB Register ............................................................... 58
Assembler
MPASM Assembler................................................... 184
AUSART ........................................................................... 119
Associated Registers
Baud Rate Generator........................................ 129
Asynchronous Mode ................................................. 121
Associated Registers
Receive..................................................... 126
Transmit.................................................... 123
Baud Rate Generator (BRG) ............................ 129
Receiver............................................................ 123
Setting up 9-bit Mode with Address Detect....... 125
Transmitter........................................................ 121
Baud Rate Generator (BRG)
Baud Rate Error, Calculating ............................ 129
Baud Rates, Asynchronous Modes .................. 130
Formulas ........................................................... 129
High Baud Rate Select (BRGH Bit) .................. 129
Synchronous Master Mode ............................... 132, 136
Associated Registers
Receive..................................................... 135
Transmit.................................................... 133
Reception.......................................................... 134
Transmission .................................................... 132
Synchronous Slave Mode
Associated Registers
Receive..................................................... 137
Transmit.................................................... 136
Reception.......................................................... 137
Transmission .................................................... 136
 2010 Microchip Technology Inc.
C
C Compilers
MPLAB C18.............................................................. 184
Capture Module. See Capture/Compare/PWM (CCP)
Capture/Compare/PWM (CCP) ........................................ 109
Associated registers w/ Capture............................... 111
Associated registers w/ Compare............................. 113
Associated registers w/ PWM................................... 117
Capture Mode........................................................... 110
CCPx Pin Configuration............................................ 110
Compare Mode......................................................... 112
CCPx Pin Configuration.................................... 112
Software Interrupt Mode ........................... 110, 112
Special Event Trigger ....................................... 112
Timer1 Mode Selection............................. 110, 112
Prescaler .................................................................. 110
PWM Mode............................................................... 114
Duty Cycle ........................................................ 115
Effects of Reset ................................................ 116
Example PWM Frequencies and
Resolutions, 20 MHZ ................................ 116
Example PWM Frequencies and
Resolutions, 8 MHz .................................. 116
Operation in Sleep Mode.................................. 116
Setup for Operation .......................................... 116
System Clock Frequency Changes .................. 116
PWM Period ............................................................. 115
Setup for PWM Operation ........................................ 116
DS41430A-page 235
PIC16F/LF720/721
Timer Resources....................................................... 109
CCP. See Capture/Compare/PWM (CCP)
CCP1CON Register ............................................................ 17
CCPR1H Register ............................................................... 17
CCPR1L Register................................................................ 17
CCPxCON Register .......................................................... 109
CKE bit ...................................................................... 147, 159
CKP bit ...................................................................... 146, 158
Clock Sources
External Modes ........................................................... 71
EC ....................................................................... 71
Code Examples
A/D Conversion ........................................................... 80
Call of a Subroutine in Page 1 from Page 0................ 24
Changing Between Capture Prescalers .................... 110
Indirect Addressing ..................................................... 25
Initializing PORTA ....................................................... 47
Initializing PORTB ....................................................... 56
Initializing PORTC....................................................... 62
Loading the SSPBUF (SSPSR) Register .................. 142
Saving W, STATUS and PCLATH Registers in RAM . 39
Writing to Flash Program Memory ............................ 165
Comparators
C2OUT as T1 Gate ..................................................... 97
Compare Module. See Capture/Compare/PWM (CCP)
Customer Change Notification Service ............................. 241
Customer Notification Service........................................... 241
Customer Support ............................................................. 241
D
D/A bit ............................................................................... 159
Data Memory....................................................................... 14
Data/Address bit (D/A) ...................................................... 159
DC and AC Characteristics ............................................... 213
DC Characteristics
Extended and Industrial ............................................ 192
Industrial and Extended ............................................ 188
Development Support ....................................................... 183
Device Configuration........................................................... 73
Code Protection .......................................................... 76
Configuration Word ..................................................... 73
User ID ........................................................................ 76
Device Overview ................................................................... 9
E
EECON1 Register ............................................................... 20
Effects of Reset
PWM mode ............................................................... 116
Electrical Specifications .................................................... 187
Errata .................................................................................... 7
F
Firmware Instructions........................................................ 173
Fixed Voltage Reference. See FVR
FSR Register................................................................. 17, 18
FVR ..................................................................................... 87
FVRCON Register............................................................... 87
G
General Purpose Register File............................................ 14
I
I2C Mode
Associated Registers ................................................ 160
INDF Register ............................................................... 17, 18
Indirect Addressing, INDF and FSR Registers.................... 25
DS41430A-page 236
Instruction Format............................................................. 173
Instruction Set................................................................... 173
ADDLW..................................................................... 175
ADDWF..................................................................... 175
ANDLW..................................................................... 175
ANDWF..................................................................... 175
MOVF ....................................................................... 178
BCF .......................................................................... 175
BSF........................................................................... 175
BTFSC ...................................................................... 175
BTFSS ...................................................................... 176
CALL......................................................................... 176
CLRF ........................................................................ 176
CLRW ....................................................................... 176
CLRWDT .................................................................. 176
COMF ....................................................................... 176
DECF ........................................................................ 176
DECFSZ ................................................................... 177
GOTO ....................................................................... 177
INCF ......................................................................... 177
INCFSZ..................................................................... 177
IORLW ...................................................................... 177
IORWF...................................................................... 177
MOVLW .................................................................... 178
MOVWF .................................................................... 178
NOP .......................................................................... 178
RETFIE ..................................................................... 179
RETLW ..................................................................... 179
RETURN................................................................... 179
RLF ........................................................................... 180
RRF .......................................................................... 180
SLEEP ...................................................................... 180
SUBLW ..................................................................... 180
SUBWF..................................................................... 181
SWAPF ..................................................................... 181
XORLW .................................................................... 181
XORWF .................................................................... 181
Summary Table ........................................................ 174
INTCON Register................................................................ 40
Internal Oscillator Block
INTOSC
Specifications ........................................... 198, 199
Internal Sampling Switch (RSS) Impedance........................ 83
Internet Address ............................................................... 241
Interrupts............................................................................. 37
ADC ............................................................................ 80
Associated registers w/ Interrupts............................... 43
Interrupt-on-Change ................................................... 56
TMR1 ........................................................................ 100
INTOSC Specifications ............................................. 198, 199
IOCB Register..................................................................... 58
L
Load Conditions................................................................ 195
M
M....................................................................................... 202
MCLR.................................................................................. 29
Internal........................................................................ 29
Memory Organization ......................................................... 13
Data ............................................................................ 14
Program ...................................................................... 13
Microchip Internet Web Site.............................................. 241
Migrating from other PIC Microcontroller Devices ............ 233
MPLAB ASM30 Assembler, Linker, Librarian ................... 184
MPLAB Integrated Development Environment Software.. 183
 2010 Microchip Technology Inc.
PIC16F/LF720/721
MPLAB PM3 Device Programmer .................................... 186
MPLAB REAL ICE In-Circuit Emulator System................. 185
MPLINK Object Linker/MPLIB Object Librarian ................ 184
O
OPCODE Field Descriptions ............................................. 173
OPTION Register ................................................................ 22
OPTION_REG Register ...................................................... 93
OSCCON Register .............................................................. 69
Oscillator
Associated registers............................................ 71, 106
Oscillator Module
EC ............................................................................... 67
Oscillator Tuning ......................................................... 70
Oscillator Parameters ....................................................... 198
Oscillator Specifications .................................................... 198
OSCTUNE Register ............................................................ 70
P
P (Stop) bit ........................................................................ 159
Packaging ......................................................................... 225
Marking ..................................................................... 225
PDIP Details.............................................................. 226
Paging, Program Memory ................................................... 24
PCL and PCLATH ............................................................... 24
Computed GOTO........................................................ 24
Stack ........................................................................... 24
PCL Register................................................................. 17, 18
PCLATH Register ......................................................... 17, 18
PCON Register ....................................................... 18, 23, 32
PIE1 Register ................................................................ 18, 41
PIR1 Register................................................................ 17, 42
PMADRH Register ............................................................ 167
PMADRL Register............................................................. 168
PMCON1 Register .................................................... 166, 168
PMDATH Register ............................................................ 167
PMDATL Register ............................................................. 167
PORTA................................................................................ 47
ANSELA Register ....................................................... 49
Associated Registers .................................................. 55
Pin Descriptions and Diagrams................................... 50
PORTA Register ......................................................... 17
RA0 ............................................................................. 50
RA1 ............................................................................. 50
RA2 ............................................................................. 50
RA3 ............................................................................. 50
RA4 ............................................................................. 50
RA5 ............................................................................. 50
RA6 ............................................................................. 50
Specifications............................................................ 199
PORTA Register ................................................................. 48
PORTB
Additional Pin Functions
ANSELB Register ............................................... 56
Weak Pull-up ...................................................... 56
Associated Registers .................................................. 61
Interrupt-on-Change.................................................... 56
Pin Descriptions and Diagrams................................... 59
PORTB Register ......................................................... 17
RB0 ............................................................................. 59
RB4 ............................................................................. 59
RB5 ............................................................................. 59
RB6 ............................................................................. 59
RB7 ............................................................................. 59
PORTB Register ................................................................. 57
PORTC
 2010 Microchip Technology Inc.
PORTC Register......................................................... 17
RC0 ............................................................................ 64
RC2 ............................................................................ 64
RC3 ............................................................................ 64
RC4 ............................................................................ 64
RC5 ............................................................................ 64
RC6 ............................................................................ 64
RC7 ............................................................................ 64
Specifications ........................................................... 199
PORTC Register................................................................. 62
Power-Down Mode (Sleep)............................................... 169
Associated Registers................................................ 170
Power-on Reset .................................................................. 29
Power-up Timer (PWRT) .................................................... 29
Specifications ........................................................... 201
PR2 Register .............................................................. 18, 148
Precision Internal Oscillator Parameters .......................... 199
Prescaler
Shared WDT/Timer0................................................... 92
Product Identification System ........................................... 243
Program Memory ................................................................ 13
Map and Stack (PIC16F720/LF720) ........................... 13
Map and Stack (PIC16F721/LF721) ........................... 13
Paging ........................................................................ 24
Program Memory Read (PMR) ......................................... 161
Associated Registers................................................ 168
Programming, Device Instructions.................................... 173
R
R/W bit .............................................................................. 159
RCREG............................................................................. 125
RCSTA Register ................................................... 17, 61, 128
Reader Response............................................................. 242
Read-Modify-Write Operations ......................................... 173
Receive Overflow Indicator bit (SSPOV) .................. 146, 158
Registers
ADCON0 (ADC Control 0) .......................................... 81
ADCON1 (ADC Control 1) .......................................... 82
ADRES (ADC Result) ................................................. 82
ANSELA (PORTA Analog Select) .............................. 49
ANSELB (PORTB Analog Select) .............................. 58
CCPxCON (CCP Operation) .................................... 109
FVRCON (Fixed Voltage Reference Register) ........... 87
INTCON (Interrupt Control) ........................................ 40
IOCB (Interrupt-on-Change PORTB).......................... 58
OPTION_REG (OPTION)........................................... 22
OPTION_REG (Option) .............................................. 93
OSCCON (Oscillator Control)..................................... 69
OSCTUNE (Oscillator Tuning).................................... 70
PCON (Power Control Register)................................. 23
PCON (Power Control) ............................................... 32
PIE1 (Peripheral Interrupt Enable 1) .......................... 41
PIR1 (Peripheral Interrupt Register 1) ........................ 42
PMADRH (Program Memory Address High) ............ 167
PMADRL (Program Memory Address Low).............. 168
PMCON1 (Program Memory Control 1) ................... 166
PMDATH (Program Memory Data High) .................. 167
PMDATL (Program Memory Data Low).................... 167
PORTA ....................................................................... 48
PORTB ....................................................................... 57
PORTC ....................................................................... 62
RCSTA (Receive Status and Control) ...................... 128
Reset Values .............................................................. 34
Reset Values (Special Registers)............................... 36
SSPCON (Sync Serial Port Control) Register .. 146, 158
SSPSTAT (Sync Serial Port Status) Register .. 147, 159
DS41430A-page 237
PIC16F/LF720/721
STATUS ...................................................................... 21
T1CON (Timer1 Control)........................................... 104
T1GCON (Timer1 Gate Control) ............................... 105
T2CON ...................................................................... 108
TRISA (Tri-State PORTA) ........................................... 48
TRISB (Tri-State PORTB) ........................................... 57
TRISC (Tri-State PORTC) .......................................... 63
TXSTA (Transmit Status and Control) ...................... 127
WPUB (Weak Pull-up PORTB) ................................... 57
Reset................................................................................... 27
Resets
Associated Registers .................................................. 36
Revision History ................................................................ 233
S
S (Start) bit ........................................................................ 159
SMP bit...................................................................... 147, 159
Software Simulator (MPLAB SIM)..................................... 185
SPBRG.............................................................................. 129
SPBRG Register ................................................................. 18
Special Event Trigger.......................................................... 80
Special Function Registers ................................................. 14
SPI Mode .......................................................................... 145
Associated Registers ................................................ 148
Typical Master/Slave Connection ............................. 139
SSP ................................................................................... 139
I2C Mode ................................................................... 149
Acknowledge..................................................... 150
Addressing ........................................................ 151
Clock Stretching................................................ 156
Clock Synchronization ...................................... 157
Firmware Master Mode ..................................... 156
Hardware Setup ................................................ 149
Multi-Master Mode ............................................ 156
Reception.......................................................... 152
Sleep Operation ................................................ 157
Start/Stop Conditions ........................................ 150
Transmission..................................................... 154
Master Mode ............................................................. 141
SPI Mode .................................................................. 139
Slave Mode ....................................................... 143
Typical SPI Master/Slave Connection....................... 139
SSPADD Register ............................................................... 18
SSPBUF Register ............................................................... 17
SSPCON Register............................................... 17, 146, 158
SSPEN bit ................................................................. 146, 158
SSPM bits ................................................................. 146, 158
SSPOV bit ................................................................. 146, 158
SSPSTAT Register ............................................. 18, 147, 159
STATUS Register................................................................ 21
Synchronous Serial Port Enable bit (SSPEN)........... 146, 158
Synchronous Serial Port Mode Select bits (SSPM) .. 146, 158
T
T1CON Register.......................................................... 17, 104
TMR1ON Bit.............................................................. 105
T1GCON Register............................................................. 105
T2CON Register.................................................. 17, 108, 148
Temperature Indicator Module ............................................ 89
Thermal Considerations .................................................... 194
Time-out Sequence............................................................. 32
Timer0 ................................................................................. 91
Associated Registers .................................................. 93
Interrupt....................................................................... 93
Operation .............................................................. 91, 96
Specifications ............................................................ 202
DS41430A-page 238
Timer1................................................................................. 95
Associated registers ................................................. 106
Asynchronous Counter Mode ..................................... 97
Reading and Writing ........................................... 97
Interrupt .................................................................... 100
Modes of Operation .................................................... 96
Module On/Off (TMR1ON Bit)................................... 105
Operation During Sleep ............................................ 100
Prescaler .................................................................... 97
Specifications ........................................................... 202
Timer1 Gate
Selecting Source ................................................ 97
TMR1H Register ......................................................... 95
TMR1L Register.......................................................... 95
Timer2
Associated registers ................................................. 108
Timers
Timer1
T1CON ............................................................. 104
T1GCON........................................................... 105
Timer2
T2CON ............................................................. 108
Timing Diagrams
A/D Conversion......................................................... 204
A/D Conversion (Sleep Mode) .................................. 205
Asynchronous Reception.......................................... 126
Asynchronous Transmission..................................... 122
Asynchronous Transmission (Back-to-Back)............ 122
Brown-out Reset (BOR)............................................ 200
Brown-out Reset Situations ........................................ 31
CLKOUT and I/O ...................................................... 199
Clock Synchronization .............................................. 157
Clock Timing ............................................................. 196
I2C Bus Data............................................................. 210
I2C Bus Start/Stop Bits ............................................. 209
I2C Reception (7-bit Address)................................... 152
I2C Slave Mode with SEN = 0 (Reception,
10-bit Address) ................................................. 153
I2C Transmission (7-bit Address).............................. 154
INT Pin Interrupt ......................................................... 38
Slave Select Synchronization ................................... 145
SPI Master Mode ...................................................... 142
SPI Master Mode (CKE = 1, SMP = 1) ..................... 207
SPI Mode (Slave Mode with CKE = 0)...................... 144
SPI Mode (Slave Mode with CKE = 1)...................... 144
SPI Slave Mode (CKE = 0) ....................................... 207
SPI Slave Mode (CKE = 1) ....................................... 208
Synchronous Reception (Master Mode, SREN) ....... 135
Synchronous Transmission ...................................... 133
Synchronous Transmission (Through TXEN) ........... 133
Time-out Sequence
Case 1 ................................................................ 32
Case 2 ................................................................ 33
Case 3 ................................................................ 33
Timer0 and Timer1 External Clock ........................... 201
Timer1 Incrementing Edge ....................................... 100
USART Synchronous Receive (Master/Slave) ......... 206
USART Synchronous Transmission (Master/Slave). 205
Wake-up from Interrupt............................................. 170
Timing Parameter Symbology .......................................... 195
Timing Requirements
I2C Bus Data............................................................. 211
I2C Bus Start/Stop Bits ............................................. 210
SPI Mode .................................................................. 209
TMR0 Register.................................................................... 17
 2010 Microchip Technology Inc.
PIC16F/LF720/721
TMR1H Register ................................................................. 17
TMR1L Register .................................................................. 17
TMR2 Register .................................................................... 17
TMRO Register ................................................................... 19
TRISA ................................................................................. 47
TRISA Register ............................................................. 18, 48
TRISB ................................................................................. 56
TRISB Register ............................................................. 18, 57
TRISC ................................................................................. 62
TRISC Register ............................................................. 18, 63
TXREG.............................................................................. 121
TXREG Register ........................................................... 17, 61
TXSTA Register .......................................................... 18, 127
BRGH Bit .................................................................. 129
U
UA ..................................................................................... 159
Update Address bit, UA .................................................... 159
USART
Synchronous Master Mode
Requirements, Synchronous Receive .............. 206
Requirements, Synchronous Transmission ...... 205
Timing Diagram, Synchronous Receive ........... 206
Timing Diagram, Synchronous Transmission ... 205
W
Wake-up Using Interrupts ................................................. 170
Watchdog Timer (WDT) ...................................................... 29
Clock Source............................................................... 29
Modes ......................................................................... 30
Period.......................................................................... 29
Specifications............................................................ 201
WCOL bit .................................................................. 146, 158
WPUB Register ................................................................... 57
Write Collision Detect bit (WCOL)............................. 146, 158
WWW Address.................................................................. 241
WWW, On-Line Support ....................................................... 7
 2010 Microchip Technology Inc.
DS41430A-page 239
PIC16F/LF720/721
NOTES:
DS41430A-page 240
 2010 Microchip Technology Inc.
PIC16F/LF720/721
THE MICROCHIP WEB SITE
CUSTOMER SUPPORT
Microchip provides online support via our WWW site at
www.microchip.com. This web site is used as a means
to make files and information easily available to
customers. Accessible by using your favorite Internet
browser, the web site contains the following
information:
Users of Microchip products can receive assistance
through several channels:
• Product Support – Data sheets and errata,
application notes and sample programs, design
resources, user’s guides and hardware support
documents, latest software releases and archived
software
• General Technical Support – Frequently Asked
Questions (FAQ), technical support requests,
online discussion groups, Microchip consultant
program member listing
• Business of Microchip – Product selector and
ordering guides, latest Microchip press releases,
listing of seminars and events, listings of
Microchip sales offices, distributors and factory
representatives
•
•
•
•
•
Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Development Systems Information Line
Customers
should
contact
their
distributor,
representative or field application engineer (FAE) for
support. Local sales offices are also available to help
customers. A listing of sales offices and locations is
included in the back of this document.
Technical support is available through the web site
at: http://support.microchip.com
CUSTOMER CHANGE NOTIFICATION
SERVICE
Microchip’s customer notification service helps keep
customers current on Microchip products. Subscribers
will receive e-mail notification whenever there are
changes, updates, revisions or errata related to a
specified product family or development tool of interest.
To register, access the Microchip web site at
www.microchip.com, click on Customer Change
Notification and follow the registration instructions.
 2010 Microchip Technology Inc.
DS41430A-page 241
PIC16F/LF720/721
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 can better serve you, please FAX your comments to the Technical Publications Manager at
(480) 792-4150.
Please list the following information, and use this outline to provide us with your comments about this document.
TO:
Technical Publications Manager
RE:
Reader Response
Total Pages Sent ________
From: Name
Company
Address
City / State / ZIP / Country
Telephone: (_______) _________ - _________
FAX: (______) _________ - _________
Application (optional):
Would you like a reply?
Y
N
Device: PIC16F/LF720/721
Literature Number: DS41430A
Questions:
1. What are the best features of this document?
2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
4. What additions to the document do you think would enhance the structure and subject?
5. What deletions from the document could be made without affecting the overall usefulness?
6. Is there any incorrect or misleading information (what and where)?
7. How would you improve this document?
DS41430A-page 242
 2010 Microchip Technology Inc.
PIC16F/LF720/721
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:
PIC16F720(1), PIC16LF720(1), PIC16F721(1), PIC16LF721(1)
Temperature
Range:
I
E
MV
=
=
=
-40C to +85C
-40C to +125C
Micro Lead Frame (UQFN)
Package:
ML
P
SO
SS
=
=
=
=
Micro Lead Frame (QFN)
Plastic DIP
SOIC
SSOP
Pattern:
3-Digit Pattern Code for QTP (blank otherwise)
PIC16F720-E/P 301 = Extended Temp., PDIP
package, QTP pattern #301
PIC16F721-I/SO = Industrial Temp., SOIC
package
Note 1:
 2010 Microchip Technology Inc.
T
= In tape and reel.
DS41430A-page 243
Worldwide Sales and Service
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
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Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://support.microchip.com
Web Address:
www.microchip.com
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Tel: 91-11-4160-8631
Fax: 91-11-4160-8632
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Tel: 43-7242-2244-39
Fax: 43-7242-2244-393
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Mississauga, Ontario,
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Tel: 905-673-0699
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Australia - Sydney
Tel: 61-2-9868-6733
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Tel: 86-28-8665-5511
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Tel: 82-53-744-4301
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Tel: 86-23-8980-9588
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Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
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Tel: 60-3-6201-9857
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Tel: 86-532-8502-7355
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Tel: 63-2-634-9065
Fax: 63-2-634-9069
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Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
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Tel: 65-6334-8870
Fax: 65-6334-8850
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Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
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Tel: 886-3-6578-300
Fax: 886-3-6578-370
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Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
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Tel: 886-7-213-7830
Fax: 886-7-330-9305
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Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
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Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
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Tel: 86-29-8833-7252
Fax: 86-29-8833-7256
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
China - Xiamen
Tel: 86-592-2388138
Fax: 86-592-2388130
China - Zhuhai
Tel: 86-756-3210040
Fax: 86-756-3210049
08/04/10
DS41430A-page 244
 2010 Microchip Technology Inc.