1997 Microchip Technology Inc.
Preliminary
DS40143B-page 1
Devices included in this data sheet:
Referred to collectively as PIC16C55X(A).
• PIC16C554 PIC16C554A
PIC16C556A
• PIC16C558 PIC16C558A
High Performance RISC CPU:
• Only 35 instructions to learn
• All single-cycle instructions (200 ns), except for
program branches which are two-cycle
• Operating speed:
- DC - 20 MHz clock input
- DC - 200 ns instruction cycle
• Interrupt capability
• 16 special function hardware registers
• 8-level deep hardware stack
• Direct, Indirect and Relative addressing modes
Peripheral Features:
• 13 I/O pins with individual direction control
• High current sink/source for direct LED drive
• Timer0: 8-bit timer/counter with 8-bit
programmable prescaler
Special Microcontroller Features:
• Power-on Reset (POR)
• Power-up Timer (PWRT) and Oscillator Start-up
Timer (OST)
• Watchdog Timer (WDT) with its own on-chip RC
oscillator for reliable operation
Device Program
Memory
Data
Memory
PIC16C554 512 80
PIC16C554A 512 80
PIC16C556A 1K 80
PIC16C558 2K 128
PIC16C558A 2K 128
Pin Diagram
Special Microcontroller Features (cont’d)
• Programmable code protection
• Power saving SLEEP mode
• Selectable oscillator options
• Serial in-circuit programming (via two pins)
• Four user programmable ID locations
CMOS Tec hnology:
• Low-power, high-speed CMOS EPROM technology
• Fully static design
• Wide operating voltage range
- 2.5V to 5.5V PIC16C55X
- 3.0 to 5.5V PIC16C55XA
• Commercial, industrial and extended temperature range
• Low power consumption
- < 2.0 mA @ 5.0V, 4.0 MHz
- 15 µ A typical @ 3.0V, 32 kHz
- < 1.0 µ A typical standby current @ 3.0V
RA1
RA0
OSC2/CLKOUT
V
DD
RB7
RB6
RB5
RB4
OSC1/CLKIN
RA2
RA3
MCLR
VSS
RB0/INT
RB1
RB2
RB3
RA4/T0CKI
RA1
RA0
OSC2/CLKOUT
V
DD
RB7
RB6
RB5
RB4
OSC1/CLKIN
RA2
RA3
MCLR
VSS
VSS
RB0/INT
RB1
RB2
RA4/T0CKI
PIC16C55X(A)
RB3RB3
VDD
PDIP, SOIC, Windowed CERDIP
SSOP
2
3
4
5
6
7
8
9
10
•1
2
3
4
5
6
7
8
9
•1
19
18
16
15
14
13
12
11
17
18
17
15
14
13
12
11
10
16
20
PIC16C55X(A)
EPROM-Based 8-Bit CMOS Microcontroller
PIC16C55X(A)
PIC16C55X(A)
DS40143B-page 2
Preliminary
1997 Microchip Technology Inc.
Device Differences
Note 1: If you change from this device to another device, please verify oscillator characteristics in your application.
Device
Voltage
Range
Oscillator
Process
Technology
(Microns)
PIC16C554 2.5 - 5.5 See Note 1 0.9
PIC16C554A 3.0 - 5.5 See Note 1 0.7
PIC16C556A 3.0 - 5.5 See Note 1 0.7
PIC16C558 2.5 - 5.5 See Note 1 0.9
PIC16C558A 3.0 - 5.5 See Note 1 0.7
1997 Microchip Technology Inc.
Preliminary
DS40143B-page 3
PIC16C55X(A)
Table of Contents
1.0 General Description......................................................................................................................................................................5
2.0 PIC16C55X(A) Device Varieties...................................................................................................................................................7
3.0 Architectural Overview .................................................................................................................................................................9
4.0 Memory Organization................................................................................................................................................................ 13
5.0 I/O Ports.................................................................................................................................................................................... 23
6.0 Timer0 Module .......................................................................................................................................................................... 29
7.0 Special Features of the CPU..................................................................................................................................................... 35
8.0 Instruction Set Summary........................................................................................................................................................... 51
9.0 Development Support................................................................................................................................................................ 63
10.0 Electrical Specifications............................................................................................................................................................. 67
11.0 Packaging Information............................................................................................................................................................... 79
Appendix A: Enhancements............................................................................................................................................................ 87
Appendix B: Compatibility............................................................................................................................................................... 87
INDEX.................................................................................................................................................................................................. 89
PIC16C55X(A) Product Identification System...................................................................................................................................... 95
To Our Valued Customers
We constantly strive to improve the quality of all our products and documentation. To this end, we recently converted to a new publishing software package which we believe will enhance our entire documentation process and
product. As in any conversion process, information may have accidently been altered or deleted. We have spent an
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PIC16C55X(A)
DS40143B-page 4
Preliminary
1997 Microchip Technology Inc.
NOTES:
1997 Microchip Technology Inc.
Preliminary
DS40143B-page 5
PIC16C55X(A)
1.0 GENERAL DESCRIPTION
The PIC16C55X(A) are 18 and 20-Pin EPROM-based
members of the versatile PIC16CXX family of low-cost,
high-performance, CMOS, fully-static, 8-bit
microcontrollers.
All PICmicro™ microcontrollers employ an advanced
RISC architecture. The PIC16C55X(A) have enhanced
core features, eight-lev el deep stack, and multiple internal and external interrupt sources. The separate
instruction and data buses of the Harvard architecture
allow a 14-bit wide instruction word with the separate
8-bit wide data. The two-stage instruction pipeline
allows all instructions to execute in a single-cycle,
except for program branches (which require two
cycles). A total of 35 instructions (reduced instruction
set) are available . Additionally , a large register set giv es
some of the architectural innovations used to achie ve a
very high performance.
PIC16C55X(A) microcontrollers typically achieve a 2:1
code compression and a 4:1 speed improvement over
other 8-bit microcontrollers in their class.
The PIC16C554(A) and PIC16C556A have 80 bytes of
RAM. The PIC16C558(A) has 128 bytes of RAM. Each
device has 13 I/O pins and an 8-bit timer/counter with
an 8-bit programmable prescaler.
PIC16C55X(A) devices hav e special features to reduce
external components, thus reducing cost, enhancing
system reliability and reducing power consumption.
There are four oscillator options, of which the single pin
RC oscillator provides a low-cost solution, the LP
oscillator minimizes power consumption, XT is a
standard crystal, and the HS is for High Speed crystals.
The SLEEP (power-down) mode offers power saving.
The user can wake up the chip from SLEEP through
several external and internal interrupts and reset.
A highly reliable Watchdog Timer with its own on-chip
RC oscillator provides protection against software
lock- up.
A UV-erasable CERDIP-packaged version is ideal for
code development while the cost-effective One-Time
Programmable (OTP) version is suitable for production
in any volume.
Table 1-1 shows the features of the PIC16C55X(A)
mid-range microcontroller families.
A simplified block diagram of the PIC16C55X(A) is
shown in Figure 3-1.
The PIC16C55X(A) series fit perfectly in applications
ranging from motor control to low-power remote sensors. The EPROM technology makes customization of
application programs (detection levels, pulse generation, timers, etc.) extremely fast and convenient. The
small footprint packages make this microcontroller
series perfect for all applications with space limitations.
Low-cost, low-power, high-performance, ease of use
and I/O flexibility make the PIC16C55X(A) very versatile.
1.1 F
amily and Upward Compatibility
Those users familiar with the PIC16C5X family of
microcontrollers will realize that this is an enhanced
version of the PIC16C5X architecture. Please refer to
Appendix A for a detailed list of enhancements. Code
written for PIC16C5X can be easily ported to
PIC16C55X(A) family of devices (Appendix B).
The PIC16C55X(A) f amily fills the niche for users w anting to migrate up from the PIC16C5X family and not
needing various peripheral features of other members
of the PIC16XX mid-range microcontroller family.
1.2 De
velopment Support
The PIC16C55X(A) family is suppor ted by a full-featured macro assembler, a software simulator, an in-circuit emulator, a low-cost de v elopment programmer and
a full-featured programmer. A “C” compiler and fuzzy
logic support tools are also available.
PIC16C55X(A)
DS40143B-page 6
Preliminary
1997 Microchip Technology Inc.
TABLE 1-1: PIC16C55X(A) FAMILY OF DEVICES
PIC16C554
PIC16C554A PIC16C556A PIC16C558 PIC16C558A
Clock
Maximum Frequency of Operation (MHz)
20 20 20 20 20
Memory
EPROM Program Memory
(x14 words)
512 512 1K 2K 2K
Data Memory (bytes) 80 80 80 128 128
Peripherals Timer Module(s) TMR0 TMR0 TMR0 TMR0 TMR0
Features
Interrupt Sources 3 3 3 3 3
I/O Pins 13 13 13 13 13
Voltage Range (Volts) 2.5-5.5 3.0-5.5 3.0-5.5 2.5-5.5 3.0-5.5
Brown-out Reset — — — — —
Packages 18-pin DIP,
SOIC;
20-pin SSOP
18-pin DIP,
SOIC;
20-pin SSOP
18-pin DIP,
SOIC;
20-pin SSOP
18-pin DIP,
SOIC;
20-pin SSOP
18-pin DIP,
SOIC;
20-pin SSOP
All PICmicro™ Family devices have Power-on Reset, selectable Watchdog Timer, selectable code protect and high
I/O current capability. All PIC16C55X(A)Family devices use serial programming with clock pin RB6 and data pin RB7.
1997 Microchip Technology Inc.
Preliminary
DS40143B-page 7
PIC16C55X(A)
2.0 PIC16C55X(A) DEVICE
VARIETIES
A variety of frequency ranges and packaging options are
available . Depending on application and production
requirements the proper device option can be selected
using the information in the PIC16C55X(A) Product
Identification System section at the end of this data
sheet. When placing orders, please use this page of the
data sheet to specify the correct part number.
2.1 UV Erasab
le Devices
The UV erasable version, offered in CERDIP package
is optimal for prototype development and pilot
programs. This version can be erased and
reprogrammed to any of the oscillator modes.
Microchip's PICSTART
and PROMATE
programmers both support programming of the
PIC16C55X(A).
2.2 One-Time-Pr
ogrammable (OTP)
Devices
The availability of OTP devices is especially useful for
customers who need the flexibility for frequent code
updates and small volume applications. In addition to
the program memory, the configuration bits must also
be programmed.
2.3 Quic
k-Turnaround-Production (QTP)
Devices
Microchip offers a QTP Programming Service for
factory production orders. This service is made
available for users who choose not to program a
medium to high quantity of units and whose code patterns have stabilized. The devices are identical to the
OTP devices but with all EPROM locations and configuration options already programmed by the factory.
Certain code and prototype verification procedures
apply before production shipments are available.
Please contact your Microchip Technology sales office
for more details.
2.4 Serializ
ed
Quick-Turnaround-Production
(SQTP
SM
)
Devices
Microchip offers a unique programming service where
a few user-defined locations in each device are
programmed with different serial numbers. The serial
numbers may be random, pseudo-random or
sequential.
Serial programming allows each device to have a
unique number which can serve as an entry-code,
password or ID number.
PIC16C55X(A)
DS40143B-page 8
Preliminary
1997 Microchip Technology Inc.
NOTES:
1997 Microchip Technology Inc.
Preliminary
DS40143B-page 9
PIC16C55X(A)
3.0 ARCHITECTURAL OVERVIEW
The high performance of the PIC16C55X(A) family can
be attributed to a number of architectural features
commonly found in RISC microprocessors. To begin
with, the PIC16C55X(A) uses a Harvard architecture,
in which, program and data are accessed from separate memories using separate busses. This improves
bandwidth over traditional von Neumann architecture
where program and data are fetched from the same
memory. Separating program and data memory further
allows instructions to be sized differently than 8-bit
wide data words. Instruction opcodes are 14-bits wide
making it possible to have all single word instructions.
A 14-bit wide program memory access bus fetches a
14-bit instruction in a single cycle. A two-stage pipeline
overlaps fetch and execution of instructions.
Consequently, all instructions (35) execute in a single-cycle (200 ns @ 20 MHz) except for program
branches.
The PIC16C554(A) addresses 512 x 14 on-chip program memory. The PIC16C556A addresses 1K x 14
program memory. The PIC16C558(A) addresses 2K x
14 program memory. All program memory is internal.
The PIC16C55X(A) can directly or indirectly address its
register files or data memory. All special function
registers including the program counter are mapped
into the data memory. The PIC16C55X(A) have an
orthogonal (symmetrical) instruction set that makes it
possible to carry out any operation on any register
using any addressing mode. This symmetrical nature
and lack of ‘special optimal situations’ make programming with the PIC16C55X(A) simple yet efficient. In
addition, the learning curve is reduced significantly.
The PIC16C55X(A) devices contain an 8-bit ALU and
working register. The ALU is a general purpose
arithmetic unit. It performs arithmetic and Boolean
functions between data in the working register and any
register file.
The ALU is 8-bits wide and capable of addition,
subtraction, shift and logical operations. Unless
otherwise mentioned, arithmetic operations are two's
complement in nature. In two-operand instructions,
typically one operand is the working register
(W register). The other operand is a file register or an
immediate constant. In single operand instructions, the
operand is either the W register or a file register.
The W register is an 8-bit working register used for ALU
operations. It is not an addressable register.
Depending on the instruction executed, the ALU may
affect the values of the Carry (C), Digit Carry (DC), and
Zero (Z) bits in the STATUS register. The C and DC bits
operate as a Bo
rrow and Digit Borrow out bit,
respectively, in subtraction. See the
SUBLW
and
SUBWF
instructions for examples.
A simplified block diagram is shown in Figure 3-1, with
a description of the device pins in Table 3-1.
PIC16C55X(A)
DS40143B-page 10
Preliminary
1997 Microchip Technology Inc.
FIGURE 3-1: BLOCK DIAGRAM
Note 1: Higher order bits are from the status register.
Device
Program
Memory
Data Memory
(RAM)
PIC16C554
PIC16C554A
PIC16C556A
PIC16C558
PIC16C558A
512 x 14
512 x 14
1K x 14
2K x 14
2K x 14
80 x 8
80 x 8
80 x 8
128 x 8
128 x 8
EPROM
Program
Memory
2K x 14
13
Data Bus
8
14
Program
Bus
Instruction reg
Program Counter
8 Level Stack
(13-bit)
RAM
File
Registers
128 x 8
Direct Addr
7
8
Addr MUX
Indirect
Addr
8
FSR reg
STATUS reg
MUX
ALU
W reg
Power-up
Timer
Oscillator
Start-up Timer
Power-on
Reset
Watchdog
Timer
Instruction
Decode &
Control
Timing
Generation
OSC1/CLKIN
OSC2/CLKOUT
MCLR
VDD, VSS
Timer0
3
PORTA
PORTB
RA1
RA4/T0CKI
RB0/INT
RB7:RB1
8
8
RAM Addr
(1)
RA0
RA2
RA3
512 x 14
to
80 x 8 to
1997 Microchip Technology Inc.
Preliminary
DS40143B-page 11
PIC16C55X(A)
TABLE 3-1: PIC16C55X(A) PINOUT DESCRIPTION
Name
DIP
SOIC
Pin #
SSOP
Pin #
I/O/P
Type
Buffer
Type
Description
OSC1/CLKIN 16 18 I ST/CMOS Oscillator crystal input/external clock source input.
OSC2/CLKOUT 15 17 O — Oscillator crystal output. Connects to crystal or resonator
in crystal oscillator mode. In RC mode, OSC2 pin outputs
CLKOUT which has 1/4 the frequency of OSC1, and
denotes the instruction cycle rate.
MCLR
/V
PP
4 4 I/P ST Master clear (reset) input/programming voltage input.
This pin is an active low reset to the device.
PORTA is a bi-directional I/O port.
RA0 17 19 I/O ST
RA1 18 20 I/O ST
RA2 1 1 I/O ST
RA3 2 2 I/O ST
RA4/T0CKI 3 3 I/O ST Can be selected to be the clock input to the Timer0
timer/counter. Output is open drain type.
PORTB is a bi-directional I/O port. PORTB can be
software programmed for internal weak pull-up on all
inputs.
RB0/INT 6 7 I/O
TTL/ST
(1)
RB0/INT can also be selected as an external
interrupt pin.
RB1 7 8 I/O TTL
RB2 8 9 I/O TTL
RB3 9 10 I/O TTL
RB4 10 11 I/O TTL Interrupt on change pin.
RB5 11 12 I/O TTL Interrupt on change pin.
RB6 12 13 I/O TTL/ST
(2)
Interrupt on change pin. Serial programming clock.
RB7 13 14 I/O TTL/ST
(2)
Interrupt on change pin. Serial programming data.
V
SS
5 5,6 P — Ground reference for logic and I/O pins.
V
DD
14 15,16 P — Positive supply for logic and I/O pins.
Legend: O = output I/O = input/output P = power
— = Not used I = Input ST = Schmitt Trigger input
TTL = TTL input
Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt.
Note 2: This buffer is a Schmitt Trigger input when used in serial programming mode.
PIC16C55X(A)
DS40143B-page 12
Preliminary
1997 Microchip Technology Inc.
3.1 Cloc
king Scheme/Instruction Cycle
The clock input (OSC1/CLKIN pin) is internally divided
by four to generate four non-overlapping quadrature
clocks namely Q1, Q2, Q3 and Q4. Internally, the
program counter (PC) is incremented every Q1, the
instruction is fetched from the program memory and
latched into the instruction register in Q4. The
instruction is decoded and executed during the
following Q1 through Q4. The clocks and instruction
execution flow are shown in Figure 3-2.
3.2 Instruction Flo
w/Pipelining
An “Instruction Cycle” consists of four Q cycles (Q1,
Q2, Q3 and Q4). The instruction fetch and execute are
pipelined such that fetch takes one instruction cycle
while decode and execute takes another instruction
cycle. However, due to the pipelining, each instruction
effectively executes in one cycle. If an instruction
causes the program counter to change (e.g.,
GOTO
)
then two cycles are required to complete the instruction
(Example 3-1).
A fetch cycle begins with the program counter (PC)
incrementing in Q1.
In the execution cycle, the f etched instruction is latched
into the “Instruction Register (IR)” in cycle Q1. This
instruction is then decoded and executed during the
Q2, Q3, and Q4 cycles. Data memory is read during Q2
(operand read) and written during Q4 (destination
write).
FIGURE 3-2: CLOCK/INSTRUCTION CYCLE
EXAMPLE 3-1: INSTRUCTION PIPELINE FLOW
Q1
Q2 Q3 Q4
Q1
Q2 Q3 Q4
Q1
Q2 Q3 Q4
OSC1
Q1
Q2
Q3
Q4
PC
OSC2/CLKOUT
(RC mode)
PC PC+1 PC+2
Fetch INST (PC)
Execute INST (PC-1) Fetch INST (PC+1)
Execute INST (PC) Fetch INST (PC+2)
Execute INST (PC+1)
Internal
phase
clock
All instructions are single cycle, except for any program branches. These take two cycles since the fetch
instruction is “flushed” from the pipeline while the new instruction is being fetched and then executed.
1. MOVLW 55h
Fetch 1 Execute 1
2. MOVWF PORTB
Fetch 2 Execute 2
3. CALL SUB_1
Fetch 3 Execute 3
4. BSF PORTA, BIT3
Fetch 4 Flush
Fetch SUB_1 Execute SUB_1
1997 Microchip Technology Inc.
Preliminary
DS40143B-page 13
PIC16C55X(A)
4.0 MEMORY ORGANIZATION
4.1 Pr
ogram Memory Organization
The PIC16C55X(A) has a 13-bit prog ram counter capable of addressing an 8K x 14 program memory space.
Only the first 512 x 14 (0000h - 01FFh) for the
PIC16C554(A), 1K x 14 (0000h - 03FFh) for the
PIC16C556A and 2K x 14 (0000h - 07FFh) for the
PIC16C558(A) are physically implemented. Accessing
a location above these boundaries will cause a
wrap-around within the first 512 x 14 space
PIC16C554(A) or 1K x 14 space PIC16C556A or 2K x
14 space PIC16C558(A). The reset vector is at 0000h
and the interrupt vector is at 0004h (Figure 4-1,
Figure 4-2, Figure 4-3).
FIGURE 4-1: PROGRAM MEMORY MAP
AND STACK FOR THE
PIC16C554/PIC6C554A
PC<12:0>
13
000h
0004
0005
01FFh
0200h
1FFFh
Stack Level 1
Stack Level 8
Reset Vector
Interrupt Vector
On-chip Program
Memory
CALL, RETURN
RETFIE, RETLW
Stack Level 2
FIGURE 4-2: PROGRAM MEMORY MAP
AND STACK FOR THE
PIC16C556A
FIGURE 4-3: PROGRAM MEMORY MAP
AND STACK FOR THE
PIC16C558/PIC16C558A
PC<12:0>
13
000h
0004
0005
03FFh
0400h
1FFFh
Stack Level 1
Stack Level 8
Reset Vector
Interrupt Vector
On-chip Program
Memory
CALL, RETURN
RETFIE, RETLW
Stack Level 2
PC<12:0>
13
000h
0004
0005
07FFh
0800h
1FFFh
Stack Level 1
Stack Level 8
Reset Vector
Interrupt Vector
On-chip Program
Memory
CALL, RETURN
RETFIE, RETLW
Stack Level 2
PIC16C55X(A)
DS40143B-page 14
Preliminary
1997 Microchip Technology Inc.
4.2 Data Memor
y Organization
The data memory (Figure 4-4 and Figure 4-5) is
partitioned into two Banks which contain the general
purpose registers and the special function registers.
Bank 0 is selected when the RP0 bit is cleared. Bank 1
is selected when the RP0 bit (STATUS <5>) is set. The
Special Function Registers are located in the first 32
locations of each Bank. Register locations 20-6Fh
(Bank0) on the PIC16C554(A)/556A and 20-7Fh
(Bank0) and A0-BFh (Bank1) on the PIC16C558(A) are
general purpose registers implemented as static RAM.
Some special purpose registers are mapped in Bank 1.
4.2.1 GENERAL PURPOSE REGISTER FILE
The register file is organized as 80 x 8 in the
PIC16C554(A)/556A and 128 x 8 in the PIC16C558(A).
Each is accessed either directly or indirectly through
the File Select Register, FSR (Section 4.4).
1997 Microchip Technology Inc. Preliminary DS40143B-page 15
PIC16C55X(A)
FIGURE 4-4: DATA MEMORY MAP FOR
THE PIC16C554(A)/556A
INDF
(1)
TMR0
PCL
STATUS
FSR
PORTA
PORTB
PCLATH
INTCON
INDF
(1)
OPTION
PCL
STATUS
FSR
TRISA
TRISB
PCLATH
INTCON
PCON
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
8Dh
8Eh
8Fh
90h
91h
92h
93h
94h
95h
96h
97h
98h
99h
9Ah
9Bh
9Ch
9Dh
9Eh
9Fh
20h
A0h
General
Purpose
Register
7Fh
FFh
Bank 0 Bank 1
File
Address
6Fh
70h
Unimplemented data memory locations, read as '0'.
Note 1: Not a physical register.
File
Address
FIGURE 4-5: DATA MEMORY MAP FOR
THE PIC16C558(A)
INDF
(1)
TMR0
PCL
STATUS
FSR
PORTA
PORTB
PCLATH
INTCON
INDF
(1)
OPTION
PCL
STATUS
FSR
TRISA
TRISB
PCLATH
INTCON
PCON
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
8Dh
8Eh
8Fh
90h
91h
92h
93h
94h
95h
96h
97h
98h
99h
9Ah
9Bh
9Ch
9Dh
9Eh
9Fh
20h
A0h
General
Purpose
Register
7Fh
FFh
Bank 0 Bank 1
File
Address
BFh
C0h
Unimplemented data memory locations, read as '0'.
Note 1: Not a physical register.
File
Address
General
Purpose
Register
PIC16C55X(A)
DS40143B-page 16 Preliminary 1997 Microchip Technology Inc.
4.2.2 SPECIAL FUNCTION REGISTERS
The special function registers are registers used by the
CPU and Peripheral functions for controlling the
desired operation of the device (Table 4-1). 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” functions are described
in this section. Those related to the operation of the
peripheral features are described in the section of that
peripheral feature.
TABLE 4-1: SPECIAL REGISTERS FOR THE PIC16C55X(A)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
POR Reset
Value on
all other
resets
(1)
Bank 0
00h INDF
Addressing this location uses contents of FSR to address data memory (not a physical
register)
xxxx xxxx xxxx xxxx
01h TMR0 Timer0 Module’s Register xxxx xxxx uuuu uuuu
02h PCL Program Counter's (PC) Least Significant Byte 0000 0000 0000 0000
03h STATUS
IRP
(2)
RP1
(2)
RP0 TO PD Z DC C
0001 1xxx 000q quuu
04h FSR Indirect data memory address pointer xxxx xxxx uuuu uuuu
05h PORTA — — — RA4 RA3 RA2 RA1 RA0 ---x xxxx ---u uuuu
06h PORTB RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 xxxx xxxx uuuu uuuu
07h Unimplemented — —
08h Unimplemented — —
09h Unimplemented — —
0Ah PCLATH — — — Write buffer for upper 5 bits of program counter ---0 0000 ---0 0000
0Bh INTCON GIE
(3) T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x
0Ch Unimplemented — —
0Dh-1Eh Unimplemented — —
1Fh Unimplemented — —
Bank 1
80h INDF
Addressing this location uses contents of FSR to address data memory (not a physical
register)
xxxx xxxx xxxx xxxx
81h OPTION RBPU
INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111
82h PCL Program Counter's (PC) Least Significant Byte 0000 0000 0000 0000
83h STATUS
— — RP0 TO PD Z DC C 0001 1xxx 000q quuu
84h FSR Indirect data memory address pointer xxxx xxxx uuuu uuuu
85h TRISA
— — — TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 ---1 1111 ---1 1111
86h TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 1111 1111 1111 1111
87h Unimplemented — —
88h Unimplemented — —
89h Unimplemented — —
8Ah PCLATH
— — — Write buffer for upper 5 bits of program counter ---0 0000 ---0 0000
8Bh INTCON GIE
(3) T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x
8Ch Unimplemented — —
8Dh Unimplemented — —
8Eh PCON
— — — — — — POR — ---- --0- ---- --u-
8Fh-9Eh Unimplemented — —
9Fh Unimplemented — —
Legend: — = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition,
shaded = unimplemented
Note 1: Other (non power-up) resets include MCLR reset and Watchdog Timer reset during normal operation.
Note 2: IRP & RPI bits are reserved, always maintain these bits clear.
Note 3: Bit 6 of INTCON register is reserved for future use. Always maintain this bit as clear.
1997 Microchip Technology Inc. Preliminary DS40143B-page 17
PIC16C55X(A)
4.2.2.1 STATUS REGISTER
The STATUS register, shown in Figure 4-6, contains
the arithmetic status of the ALU, the RESET status and
the bank select bits for data memory.
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 T
O and PD bits are not
writable. Therefore, the result of an instruction with the
STATUS register as the destination may be different
than intended.
For example, CLRF STATUS will clear the upper-three
bits and set the Z bit. This lea ves the status register as
000uu1uu (where u = unchanged).
It is recommended, therefore, that only BCF, BSF,
SWAPF and MOVWF instructions be used to alter the ST ATUS register because these instructions do not affect
any status bits. For other instructions, not affecting any
status bits, see the “Instruction Set Summary”.
Note 1: The IRP and RP1 bits (STATUS<7:6>)
are not used by the PIC16C55X(A) and
should be programmed as ’0'. Use of
these bits as general purpose R/W bits is
NOT recommended, since this may
affect upward compatibility with future
products.
Note 2: The C and DC bits operate as a Borro
w
and Digit Borrow out bit, respectively, in
subtraction. See the SUBLW and SUBWF
instructions for examples.
FIGURE 4-6: STATUS REGISTER (ADDRESS 03H OR 83H)
Reserved Reserved R/W-0 R-1 R-1 R/W-x R/W-x R/W-x
IRP RP1 RP0 TO PD Z DC C R = Readable bit
W = Writable bit
- n = Value at POR reset
- x = Unknown at POR reset
bit7 bit0
bit 7: IRP: Register Bank Select bit (used for indirect addressing)
1 = Bank 2, 3 (100h - 1FFh)
0 = Bank 0, 1 (00h - FFh)
The IRP bit is reserved on the PIC16C55X(A), always maintain this bit clear.
bit 6-5: RP1:RP0: Register Bank Select bits (used for direct addressing)
11 = Bank 3 (180h - 1FFh)
10 = Bank 2 (100h - 17Fh)
01 = Bank 1 (80h - FFh)
00 = Bank 0 (00h - 7Fh)
Each bank is 128 bytes. The RP1 bit is reserved on the PIC16C55X(A), always maintain this bit clear.
bit 4: T
O: 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/borro
w bit (ADDWF, ADDLW,SUBLW,SUBWF instructions)(for borrow the polarity is reversed)
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/borro
w bit (ADDWF, ADDLW,SUBLW,SUBWF instructions)
1 = A carry-out from the most significant bit of the result occurred
0 = No carry-out from the most significant bit of the result occurred
Note: For borro
w 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 or low order bit of
the source register.
PIC16C55X(A)
DS40143B-page 18 Preliminary 1997 Microchip Technology Inc.
4.2.2.2 OPTION REGISTER
The OPTION register is a readable and writable
register which contains various control bits to configure
the TMR0/WDT prescaler, the external RB0/INT
interrupt, TMR0 and the weak pull-ups on PORTB.
Note: To achieve a 1:1 prescaler assignment for
TMR0, assign the prescaler to the WDT
(PSA = 1).
FIGURE 4-7: OPTION REGISTER (ADDRESS 81H)
R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1
RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 R = Readable bit
W = Writable bit
- n = Value at POR reset
bit7 bit0
bit 7: RBPU: PORTB Pull-up Enable bit
1 = PORTB pull-ups are disabled
0 = PORTB pull-ups are enabled by individual port latch values
bit 6: INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of RB0/INT pin
0 = Interrupt on falling edge of RB0/INT pin
bit 5: T0CS: TMR0 Clock Source Select bit
1 = Transition on RA4/T0CKI pin
0 = Internal instruction cycle clock (CLKOUT)
bit 4: T0SE: TMR0 Source Edge Select bit
1 = Increment on high-to-low transition on RA4/T0CKI pin
0 = Increment on low-to-high transition on RA4/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: PS2:PS0: Prescaler Rate Select bits
000
001
010
011
100
101
110
111
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
1 : 256
1 : 1
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
Bit Value TMR0 Rate WDT Rate
1997 Microchip Technology Inc. Preliminary DS40143B-page 19
PIC16C55X(A)
4.2.2.3 INTCON REGISTER
The INTCON register is a readable and writable
register which contains the various enable and flag bits
for all interrupt sources.
Note: Interrupt flag bits get set when an interrupt
condition occurs regardless of the state of
its corresponding enable bit or the global
enable bit, GIE (INTCON<7>).
FIGURE 4-8: INTCON REGISTER (ADDRESS 0BH OR 8BH)
R/W-0 Reserved R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-x
GIE — T0IE INTE RBIE T0IF INTF RBIF R = Readable bit
W = Writable bit
- n = Value at POR reset
- x = Unknown at POR reset
bit7 bit0
bit 7: GIE: Global Interrupt Enable bit
1 = Enables all un-masked interrupts
0 = Disables all interrupts
bit 6:
— = Reserved for future use. Always maintain this bit clear.
bit 5: T0IE: TMR0 Overflow Interrupt Enable bit
1 = Enables the TMR0 interrupt
0 = Disables the TMR0 interrupt
bit 4: INTE: RB0/INT External Interrupt Enable bit
1 = Enables the RB0/INT external interrupt
0 = Disables the RB0/INT external interrupt
bit 3: RBIE: RB Port Change Interrupt Enable bit
1 = Enables the RB port change interrupt
0 = Disables the RB port change interrupt
bit 2: T0IF: TMR0 Overflow Interrupt Flag bit
1 = TMR0 register has overflowed (must be cleared in software)
0 = TMR0 register did not overflow
bit 1: INTF: RB0/INT External Interrupt Flag bit
1 = The RB0/INT external interrupt occurred (must be cleared in software)
0 = The RB0/INT external interrupt did not occur
bit 0: RBIF: RB Port Change Interrupt Flag bit
1 = When at least one of the RB7:RB4 pins changed state (must be cleared in software)
0 = None of the RB7:RB4 pins have changed state
PIC16C55X(A)
DS40143B-page 20 Preliminary 1997 Microchip Technology Inc.
4.2.2.4 PCON REGISTER
The PCON register contains flag bits to differentiate
between a Pow er-on Reset, an e xternal MCLR
reset or
WDT reset. See Section 7.3 and Section 7.4 for
detailed reset operation.
FIGURE 4-9: PCON REGISTER (ADDRESS 8Eh)
U-0 U-0 U-0 U-0 U-0 U-0 R/W-0 U-0
— — — — — — POR — R = Readable bit
W = Writable bit
U = Unimplemented bit,
read as ‘0’
- n = Value at POR reset
bit7 bit0
bit 7-2: Unimplemented: Read as '0'
bit 1: POR
: Power-on Reset Status bit
1 = No Power-on Reset occurred
0 = Power-on Reset occurred
bit 0: Unimplemented: Read as '0'
1997 Microchip Technology Inc. Preliminary DS40143B-page 21
PIC16C55X(A)
4.3 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 bits (PC<12:8>) are not directly
readable or writable and come from PCLATH. On any
reset, the PC is cleared. Figure 4-10 shows the two
situations for the loading of the PC. The upper example in
the figure shows how the PC is loaded on a write to PCL
(PCLATH<4:0> → PCH). The lo wer example in the figure
shows how the PC is loaded during a CALL or GOTO
instruction (PCLATH<4:3> → PCH).
FIGURE 4-10: LOADING OF PC IN
DIFFERENT SITUATIONS
4.3.1 COMPUTED GOTO
A computed GOTO is accomplished by adding an
offset to the program counter (ADDWF PCL). When doing
a table read using a computed GOTO method, care
should be exercised if the tab le location crosses a PCL
memory boundary (each 256 byte block). Refer to the
application note
“Implementing a Table Read"
(AN556).
PC
12 8 7 0
5
PCLA TH<4:0>
PCLA TH
Instr
uction with
ALU result
GOTO, CALL
Opcode <10:0>
8
PC
12 11 10 0
11
PCLATH<4:3>
PCH PCL
8 7
2
PCLATH
PCH PCL
PCL as
Destination
4.3.2 STACK
The PIC16C55X(A) family has an 8 level deep x 13-bit
wide hardware stack (Figure 4-1, Figure 4-2 and
Figure 4-3). 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 buff er . 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).
Note 1: There are no STATUS bits to indicate
stack overflow or stack underflow
conditions.
Note 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 vectoring to an interrupt
address.
PIC16C55X(A)
DS40143B-page 22 Preliminary 1997 Microchip Technology Inc.
4.4 Indirect Addressing, INDF and FSR
Registers
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 (STATUS<7>), as
shown in Figure 4-11. However, IRP is not used in the
PIC16C55X(A).
A simple program to clear RAM locations 20h-2Fh
using indirect addressing is shown in Example 4-1.
EXAMPLE 4-1: INDIRECT ADDRESSING
movlw 0x20 ;initialize pointer
movwf FSR ;to RAM
N
EXT clrf INDF ;clear INDF register
incf FSR ;inc pointer
btfss FSR,4 ;all done?
goto NEXT ;no clear next
;yes continue
CONTINUE:
FIGURE 4-11: DIRECT/INDIRECT ADDRESSING PIC16C55X(A)
For memory map detail see Figure 4-4 and Figure 4-5.
Note 1: The RP1 and IRP bits are reserved, always maintain these bits clear.
Data
Memory
Indirect AddressingDirect Addressing
bank select location select
(1)
RP1 RP0 6
0
from opcode
IRP
(1)
FSR register
7
0
bank select
location select
00 01 10 11
00h
7Fh
00h
7Fh
Bank 0 Bank 1 Bank 2 Bank 3
not used
1997 Microchip Technology Inc. Preliminary DS40143B-page 23
PIC16C55X(A)
5.0 I/O PORTS
The PIC16C55X(A) ha ve two ports, PORT A and POR TB.
5.1 PORT A and TRISA Registers
PORTA is a 5-bit wide latch. RA4 is a Schmitt Trigger input
and an open drain output. Port RA4 is multiple xed with the
T0CKI clock input. All other RA port pins have Schmitt
Trigger input levels and full CMOS output driv ers . All pins
have data direction bits (TRIS registers) which can configure these pins as input or output.
A '1' in the TRISA register puts the corresponding output
driver in a hi- impedance mode. A '0' in the TRISA register
puts the contents of the output latch on the selected pin(s).
Reading the PORTA register reads the status of the pins,
whereas writing to it will write to the port latch. All write
operations are read-modify-write operations. So a write
to a port implies that the port pins are first read, then this
value is modified and written to the port data latch.
FIGURE 5-1: BLOCK DIAGRAM OF
PORT PINS RA<3:0>
Note: On reset, the TRISA register is set to all inputs.
Data
bus
Q
D
Q
CK
QD
Q
CK
Q D
EN
P
N
WR
PortA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
Schmitt
input
buffer
V
SS
VDD
I/O pin
Trigger
FIGURE 5-2: BLOCK DIAGRAM OF RA4 PIN
Data
bus
WR
PORTA
WR
TRISA
RD PORTA
Data Latch
TRISA Latch
RD TRISA
Schmitt
Trigger
input
buffer
N
V
SS
I/O pin
(1)
TMR0 clock input
Note 1: I/O pin has protection diodes to V
SS only.
QD
Q
CK
QD
Q
CK
EN
Q D
EN
PIC16C55X(A)
DS40143B-page 24 Preliminary 1997 Microchip Technology Inc.
TABLE 5-1: PORTA FUNCTIONS
TABLE 5-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Name Bit #
Buffer
Type
Function
RA0 bit0 ST Input/output
RA1 bit1 ST Input/output
RA2 bit2 ST Input/output
RA3 bit3 ST Input/output
RA4/T0CKI bit4 ST Input/output or external clock input for TMR0. Output is open drain type.
Legend: ST = Schmitt Trigger input
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
POR
Value on
All Other Resets
05h PORTA — — — RA4 RA3 RA2 RA1 RA0
---x xxxx ---u uuuu
85h TRISA — — — TRISA4 TRISA3 TRISA2 TRISA1 TRISA0
---1 1111 ---1 1111
Legend: — = Unimplemented locations, read as ‘0’
Note: Note: Shaded bits are not used by PORTA.
1997 Microchip Technology Inc. Preliminary DS40143B-page 25
PIC16C55X(A)
5.2 PORTB and TRISB Registers
PORTB is an 8-bit wide bi-directional port. The
corresponding data direction register is TRISB. A '1' in
the TRISB register puts the corresponding output driver
in a high impedance mode. A '0' in the TRISB register
puts the contents of the output latch on the selected
pin(s).
Reading PORTB register reads the status of the pins,
whereas writing to it will write to the port latch. All write
operations are read-modify-write operations. So a write
to a port implies that the por t pins are first read, then
this value is modified and written to the port data latch.
Each of the PORTB pins has a weak internal pull-up
(≈200 µA typical). A single control bit can turn on all the
pull-ups. This is done by clearing the RBPU
(OPTION<7>) bit. The weak pull-up is automatically
turned off when the port pin is configured as an output.
The pull-ups are disabled on Power-on Reset.
Four of PORTB’s pins, RB7:RB4, have an interrupt on
change feature. Only pins configured as inputs can
cause this interrupt to occur (i.e., any RB7:RB4 pin
configured as an output is excluded from the interrupt
on change comparison). The input pins (of RB7:RB4)
are compared with the old value latched on the last
read of PORTB. The “mismatch” outputs of RB7:RB4
are OR’ed together to generate the RBIF interrupt (flag
latched in INTCON<0>).
FIGURE 5-3: BLOCK DIAGRAM OF
RB7:RB4 PINS
Data Latch
From other
RBPU
(2)
P
V
DD
I/O
QD
CK
QD
CK
Q D
EN
Q D
EN
Data bus
WR PortB
WR TRISB
Set RBIF
TRIS Latch
RD TRISB
RD PortB
RB7:RB4 pins
weak
pull-up
RD Port
Latch
TTL
Input
Buffer
pin
(1)
Note 1: I/O pins have diode protection to VDD and VSS.
Note 2: TRISB = 1 enables weak pull-up if RBPU
= '0'
(OPTION<7>).
ST
Buffer
RB7:RB6 in serial programming mode
This interrupt can wake the device from SLEEP. The
user, in the interrupt service routine, can clear the
interrupt in the following manner:
a) Any read or write of PORTB. This will end the
mismatch condition.
b) Clear flag bit RBIF.
A mismatch condition will continue to set flag bit RBIF.
Reading PORTB will end the mismatch condition, and
allow flag bit RBIF to be cleared.
This interrupt on mismatch feature, together with
software configurable pull-ups on these four pins allow
easy interface to a key pad and make it possible for
wake-up on key-depression. (See AN552 in the
Microchip
Embedded Control Handbook
.)
The interrupt on change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt on change
feature. Polling of PORTB is not recommended while
using the interrupt on change feature.
FIGURE 5-4: BLOCK DIAGRAM OF
RB3:RB0 PINS
Note: If a change on the I/O pin should occur when the
read operation is being executed (start of the Q2
cycle), then the RBIF interrupt flag may not
get set.
Data Latch
RBPU
(2)
P
V
DD
QD
CK
QD
CK
Q D
EN
Data bus
WR PortB
WR TRISB
RD TRISB
RD PortB
weak
pull-up
RD Port
RB0/INT
I/O
pin
(1)
TTL
Input
Buffer
Note 1: I/O pins have diode protection to VDD and VSS.
Note 2: TRISB = 1 enables weak pull-up if RBPU
= '0'
(OPTION<7>).
ST
Buffer
PIC16C55X(A)
DS40143B-page 26 Preliminary 1997 Microchip Technology Inc.
TABLE 5-3: PORTB FUNCTIONS
TABLE 5-4: SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Name Bit # Buffer Type Function
RB0/INT bit0
TTL/ST
(1)
Input/output or external interrupt input. Internal software programmable
weak pull-up.
RB1 bit1 TTL Input/output pin. Internal software programmable weak pull-up.
RB2 bit2 TTL Input/output pin. Internal software programmable weak pull-up.
RB3 bit3 TTL Input/output pin. Internal software programmable weak pull-up.
RB4 bit4 TTL Input/output pin (with interrupt on change). Internal software
programmable weak pull-up.
RB5 bit5 TTL Input/output pin (with interrupt on change). Internal software
programmable weak pull-up.
RB6 bit6
TTL/ST
(2)
Input/output pin (with interrupt on change). Internal software
programmable weak pull-up. Serial programming clock pin.
RB7 bit7
TTL/ST
(2)
Input/output pin (with interrupt on change). Internal software
programmable weak pull-up. Serial programming data pin.
Legend: ST = Schmitt Trigger, TTL = TTL input
Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt.
Note 2: This buffer is a Schmitt Trigger input when used in serial programming mode.
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
POR
Value on
All Other Rests
06h PORTB RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0
uuuu uuuu xxxx xxxx
86h TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0
1111 1111 1111 1111
81h OPTION RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0
1111 1111 1111 1111
Note: Shaded bits are not used by PORTB.
1997 Microchip Technology Inc. Preliminary DS40143B-page 27
PIC16C55X(A)
5.3 I/O Programming Considerations
5.3.1 BI-DIRECTIONAL I/O PORTS
Any instruction which writes, operates internally as a
read followed by a write operation. The BCF and BSF
instructions, for example, read the register into the
CPU, ex ecute the bit operation and write the result back
to the register. Caution must be used when these
instructions are applied to a port with both inputs and
outputs defined. For example, a BSF operation on bit5
of PORTB will cause all eight bits of PORTB to be read
into the CPU. Then the BSF operation takes place on
bit5 and PORTB is written to the output latches. If
another bit of PORTB is used as a bidirectional I/O pin
(e.g., bit0) and it is defined as an input at this time, the
input signal present on the pin itself would be read into
the CPU and re-written to the data latch of this
particular pin, overwriting the previous content. As long
as the pin stays in the input mode, no problem occurs.
However, if bit0 is switched into output mode later on,
the content of the data latch may now be unknown.
Reading the port register, reads the values of the port
pins. Writing to the port register writes the value to the
port latch. When using read modify write instructions
(ex. BCF, BSF , etc.) on a port, the value of the port pins
is read, the desired operation is done to this value, and
this value is then written to the port latch.
Example 5-1 shows the effect of two sequential
read-modify-write instructions (ex., BCF, BSF, etc.) on
an I/O port.
A pin actively outputting a Low or High should not be
driven from external devices at the same time in order
to change the level on this pin (“wired-or”, “wired-and”).
The resulting high output currents may damage
the chip.
EXAMPLE 5-1: READ-MODIFY-WRITE
INSTRUCTIONS ON AN
I/O PORT
5.3.2 SUCCESSIVE OPERATIONS ON I/O PORTS
The actual write to an I/O port happens at the end of an
instruction cycle, whereas for reading, the data must be
valid at the beginning of the instruction cycle
(Figure 5-5). Therefore, care must be exercised if a
write followed by a read operation is carried out on the
same I/O port. The sequence of instructions should be
such to allow the pin voltage to stabilize (load
dependent) before the next instruction which causes
that file to be read into the CPU is executed. Otherwise ,
the previous state of that pin may be read into the CPU
rather than the new state. When in doubt, it is better to
separate these instructions with an NOP or another
instruction not accessing this I/O port.
;;Initial PORT settings: PORTB<7:4> Inputs
; PORTB<3:0> Outputs
;;PORTB<7:6> have external pull-up and are not
connected to other circuitry
;
; PORT latch PORT pins
; ---------- ----------
BCF PORTB, 7 ; 01pp pppp 11pp pppp
BCF PORTB, 6 ; 10pp pppp 11pp pppp
BSF STATUS,RP0 ;
BCF TRISB, 7 ; 10pp pppp 11pp pppp
BCF TRISB, 6 ; 10pp pppp 10pp pppp
;
; Note that the user may have expected the pin
; values to be 00pp pppp. The 2nd BCF caused
; RB7 to be latched as the pin value (High).
FIGURE 5-5: SUCCESSIVE I/O OPERATION
Note:
This example shows write to PORTB
followed by a read from PORTB.
Note that:
data setup time = (0.25 T
CY - TPD)
where TCY = instruction cycle and
TPD = propagation delay of Q1 cycle
to output valid.
Therefore, at higher clock frequencies,
a write followed by a read may be
problematic.
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
RB <7:0>
Port pin
sampled here
PC
PC + 1 PC + 2 PC + 3
NOPNOPMOVF PORTB, W
Read PORTB
MOVWF PORTB
Write to
PORTB
PC
Instruction
fetched
TPD
Execute
MOVWF
PORTB
Execute
MOVF
PORTB, W
Execute
NOP
RB7:RB0
PIC16C55X(A)
DS40143B-page 28 Preliminary 1997 Microchip Technology Inc.
NOTES:
1997 Microchip Technology Inc. Preliminary DS40143B-page 29
PIC16C55X(A)
6.0 TIMER0 MODULE
The Timer0 module timer/counter has the following
features:
• 8-bit timer/counter
• Readable and writable
• 8-bit software programmable prescaler
• Internal or external clock select
• Interrupt on overflow from FFh to 00h
• Edge select for external clock
Figure 6-1 is a simplified block diagram of the Timer0
module.
Timer mode is selected by clearing the T0CS bit
(OPTION<5>). In timer mode, the TMR0 will increment
every instruction cycle (without prescaler). If Timer0 is
written, the increment is inhibited for the following two
cycles (Figure 6-2 and Figure 6-3). The user can work
around this by writing an adjusted value to TMR0.
Counter mode is selected by setting the T0CS bit. In
this mode Timer0 will increment either on every rising
or falling edge of pin RA4/T0CKI. The incrementing
edge is determined by the source edge (T0SE) control
bit (OPTION<4>). Clearing the T0SE bit selects the
rising edge. Restrictions on the e xternal clock input are
discussed in detail in Section 6.2.
The prescaler is shared between the Timer0 module
and the WatchdogTimer. The prescaler assignment is
controlled in software by the control bit PSA
(OPTION<3>). Clearing the PSA bit will assign the
prescaler to Timer0. The prescaler is not readable or
writable. When the prescaler is assigned to the Timer0
module, prescale value of 1:2, 1:4, ..., 1:256 are
selectable. Section 6.3 details the operation of the
prescaler.
6.1 TIMER0 Interrupt
Timer0 interrupt is generated when the TMR0 register
timer/counter overflows from FFh to 00h. This overflow
sets the T0IF bit. The interrupt can be masked by
clearing the T0IE bit (INTCON<5>). The T0IF bit
(INTCON<2>) must be cleared in software by the
Timer0 module interrupt service routine before
re-enabling this interrupt. The Timer0 interrupt cannot
wake the processor from SLEEP since the timer is shut
off during SLEEP. See Figure 6-4 for Timer0 interrupt
timing.
FIGURE 6-1: TIMER0 BLOCK DIAGRAM
FIGURE 6-2: TIMER0 (TMR0) TIMING: INTERNAL CLOCK/NO PRESCALER
Note 1: Bits, T0SE, T0CS, PS2, PS1, PS0 and PSA are located in the OPTION register.
2: The prescaler is shared with Watchdog Timer (Figure 6-6)
RA4/T0CKI
T0SE
0
1
1
0
pin
T0CS
FOSC/4
Programmable
Prescaler
Sync with
Internal
clocks
TMR0
PSout
(2 cycle delay)
PSout
Data bus
8
Set Flag bit T0IF
on Overflow
PSA
PS2:PS0
PC-1
Q1 Q2 Q3 Q4
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
PC
(Program
Counter)
Instruction
Fetch
TMR0
PC PC+1 PC+2 PC+3 PC+4 PC+5 PC+6
T0
T0+1 T0+2 NT0 NT0 NT0 NT0+1 NT0+2
T0
MOVWF TMR0
MOVF TMR0,W MOVF TMR0,W MOVF TMR0,W MOVF TMR0,W MOVF TMR0,W
Write TMR0
executed
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0 + 1
Read TMR0
reads NT0 + 2
Instruction
Executed
PIC16C55X(A)
DS40143B-page 30 Preliminary 1997 Microchip Technology Inc.
FIGURE 6-3: TIMER0 TIMING: INTERNAL CLOCK/PRESCALE 1:2
FIGURE 6-4: TIMER0 INTERRUPT TIMING
PC-1
Q1 Q2 Q3 Q4
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
PC
(Program
Counter)
Instruction
Fetch
TMR0
PC PC+1 PC+2 PC+3 PC+4 PC+5 PC+6
T0 NT0+1
MOVWF TMR0
MOVF TMR0,W MOVF TMR0,W MOVF TMR0,W MOVF TMR0,W MOVF TMR0,W
Write TMR0
executed
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0 + 1
T0+1
NT0
Instruction
Execute
Q2Q1 Q3 Q4Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4
1
1
OSC1
CLKOUT(3)
TMR0 timer
T0IF bit
(INTCON<2>)
FEh
GIE bit
(INTCON<7>)
INSTR
UCTION FLOW
PC
Instruction
fetched
PC
PC +1 PC +1 0004h 0005h
Instruction
executed
Inst (PC)
Inst (PC-1)
Inst (PC+1)
Inst (PC)
Inst (0004h) Inst (0005h)
Inst (0004h)Dummy cycle Dummy cycle
FFh 00h 01h 02h
Note 1: T0IF interrupt flag is sampled here (every Q1).
2: Interrupt latency = 4Tcy, where Tcy = instruction cycle time.
3: CLKOUT is available only in RC oscillator mode.
Interrupt Latency Time
1997 Microchip Technology Inc. Preliminary DS40143B-page 31
PIC16C55X(A)
6.2 Using Timer0 with External Clock
When an external clock input is used for Timer0, it must
meet certain requirements. The external clock
requirement is due to internal phase clock (T
OSC)
synchronization. Also, there is a delay in the actual
incrementing of Timer0 after synchronization.
6.2.1 EXTERNAL CLOCK SYNCHRONIZATION
When no prescaler is used, the external clock input is
the same as the prescaler output. The synchronization
of T0CKI with the internal phase clocks is
accomplished by sampling the prescaler output on the
Q2 and Q4 cycles of the internal phase clocks
(Figure 6-5). Therefore, it is necessary for T0CKI to be
high for at least 2T
OSC (and a small RC delay of 20 ns)
and low for at least 2T
OSC (and a small RC delay of
20 ns). Refer to the electrical specification of the
desired device.
When a prescaler is used, the external clock input is
divided by the asynchronous ripple-counter type
prescaler so that the prescaler output is symmetrical.
For the external clock to meet the sampling
requirement, the ripple-counter must be taken into
account. Therefore, it is necessary for T0CKI to have a
period of at least 4T
OSC (and a small RC delay of
40 ns) divided by the prescaler value. The only
requirement on T0CKI high and low time is that the y do
not violate the minimum pulse width requirement of
10 ns. Refer to parameters 40, 41 and 42 in the
electrical specification of the desired device.
6.2.2 TIMER0 INCREMENT DELAY
Since the prescaler output is synchronized with the
internal clocks, there is a small delay from the time the
external clock edge occurs to the time the TMR0 is
actually incremented. Figure 6-5 shows the delay from
the external clock edge to the timer incrementing.
FIGURE 6-5: TIMER0 TIMING WITH EXTERNAL CLOCK
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
External Clock Input or
Prescaler output
(2)
External Clock/Prescaler
Output after sampling
Increment Timer0 (Q4)
Timer0
T0 T0 + 1 T0 + 2
Small pulse
misses sampling
Note 1: Delay from clock input change to Timer0 increment is 3Tosc to 7Tosc. (Duration of Q = Tosc).
Therefore, the error in measuring the interval between two edges on Timer0 input = ±4Tosc max.
2: External clock if no prescaler selected, Prescaler output otherwise.
3: The arrows indicate the points in time where sampling occurs.
(3)
(1)
PIC16C55X(A)
DS40143B-page 32 Preliminary 1997 Microchip Technology Inc.
6.3 Prescaler
An 8-bit counter is available as a prescaler for the
Timer0 module, or as a postscaler for the Watchdog
Timer, respectively (Figure 6-6). For simplicity, this
counter is being referred to as “prescaler” throughout
this data sheet. Note that there is only one prescaler
available which is mutually exclusive between the
Timer0 module and the Watchdog Timer. Thus, a
prescaler assignment for the Timer0 module means
that there is no prescaler for the Watchdog Timer, and
vice-versa.
The PSA and PS2:PS0 bits (OPTION<3:0>) determine
the prescaler assignment and prescale ratio.
When assigned to the Timer0 module, all instructions
writing to the TMR0 register (e.g., CLRF 1, MOVWF 1,
BSF 1,x....etc.) will clear the prescaler. When
assigned to WDT, a CLRWDT instruction will clear the
prescaler along with the Watchdog Timer. The
prescaler is not readable or writable.
FIGURE 6-6: BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
T0CKI
T0SE
pin
M
U
X
CLKOUT (=Fosc/4)
SYNC
2
Cycles
TMR0 reg
8-bit Prescaler
8-to-1MUX
M
U
X
M U X
Watchdog
Timer
PSA
0
1
0
1
WDT
Time-out
PS0 - PS2
8
Note: T0SE, T0CS, PSA, PS0-PS2 are bits in the OPTION register.
PSA
WDT Enable bit
M
U
X
0
1
0
1
Data Bus
Set flag bit T0IF
on Overflow
8
PSA
T0CS
1997 Microchip Technology Inc. Preliminary DS40143B-page 33
PIC16C55X(A)
6.3.1 SWITCHING PRESCALER ASSIGNMENT
The prescaler assignment is fully under software
control (i.e., it can be changed “on the fly” during
program execution). To avoid an unintended device
RESET, the following instruction sequence
(Example 6-1) must be executed when changing the
prescaler assignment from Timer0 to WDT. Lines 5-7
are required only if the desired postscaler rate is 1:1
(PS<2:0> = 000) or 1:2 (PS<2:0> = 001).
EXAMPLE 6-1: CHANGING PRESCALER
(TIMER0→WDT)
1.BCF STATUS, RP0 ;Skip if already in
; Bank 0
2.CLRWDT ;Clear WDT
3.CLRF TMR0 ;Clear TMR0 & Prescaler
4.BSF STATUS, RP0 ;Bank 1
5.MOVLW '00101111’b; ;These 3 lines (5, 6, 7)
6.MOVWF OPTION ; are required only if
; desired PS<2:0> are
7.CLRWDT ; 000 or 001
8.MOVLW '00101xxx’b ;Set Postscaler to
9.MOVWF OPTION ; desired WDT rate
10.BCF STATUS, RP0 ;Return to Bank 0
To change prescaler from the WDT to the TMR0
module use the sequence shown in Example 6-2. This
precaution must be taken even if the WDT is disabled.
EXAMPLE 6-2: CHANGING PRESCALER
(WDT→TIMER0)
CLRWDT ;Clear WDT and
;prescaler
BSF STATUS, RP0
MOVLW b'xxxx0xxx' ;Select TMR0, new
;prescale value and
;clock source
MOVWF OPTION
BCF STATUS, RP0
TABLE 6-1: REGISTERS ASSOCIATED WITH TIMER0
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
POR
Value on
All Other Resets
01h TMR0 Timer0 module’s register uuuu uuuu xxxx xxxx
0Bh/8Bh INTCON GIE
+ T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x
81h OPTION
RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111
85h TRISA
— — — TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 ---1 1111 ---1 1111
Legend: — = Unimplemented locations, read as ‘0’.
+ = Reserved for future use.
Note: Shaded bits are not used by TMR0 module.
PIC16C55X(A)
DS40143B-page 34 Preliminary 1997 Microchip Technology Inc.
NOTES:
1997 Microchip Technology Inc. Preliminary DS40143B-page 35
PIC16C55X(A)
7.0 SPECIAL FEATURES OF THE
CPU
What sets a microcontroller apart from other
processors are special circuits to deal with the needs of
real time applications. The PIC16C55X(A) family has a
host of such features intended to maximize system
reliability, minimize cost through elimination of external
components, provide power saving operating modes
and offer code protection.
These are:
1. OSC selection
2. Reset
Power-on Reset (POR)
Power-up Timer (PWRT)
Oscillator Start-Up Timer (OST)
3. Interrupts
4. Watchdog Timer (WDT)
5. SLEEP
6. Code protection
7. ID Locations
8. In-circuit serial programming™
The PIC16C55X(A) has a Watchdog Timer which is
controlled by configuration bits. It runs off its own RC
oscillator for added reliability. There are two timers that
offer necessary delays on power-up. One is the
Oscillator Start-up Timer (OST), intended to keep the
chip in reset until the crystal oscillator is stable. The
other is the Pow er-up Timer (PWRT), which pro vides a
fixed delay of 72 ms (nominal) on power-up only,
designed to keep the part in reset while the power
supply stabilizes. With these two functions on-chip,
most applications need no external reset circuitry.
The SLEEP mode is designed to offer a very low
current power-down mode. The user can wak e-up from
SLEEP through external reset, Watchdog Timer
wake-up or through an interrupt. Several oscillator
options are also made available to allow the part to fit
the application. The RC oscillator option saves system
cost while the LP crystal option saves power. A set of
configuration bits are used to select various options.
PIC16C55X(A)
DS40143B-page 36 Preliminary 1997 Microchip Technology Inc.
7.1 Configuration Bits
The configuration bits can be programmed (read as '0')
or left unprogrammed (read as '1') to select various
device configurations. These bits are mapped in
program memory location 2007h.
The user will note that address 2007h is beyond
the user program memory space. In fact, it belongs
to the special test/configuration memory space
(2000h – 3FFFh), which can be accessed only during
programming.
FIGURE 7-1: CONFIGURATION WORD
CP1
CP0
1
CP1
CP0
1
CP1
CP0
1
— Reserved CP1
CP0
1
PWRTE WDTE F0SC1 F0SC0
CONFIG Address
REGISTER: 2007h
bit13 bit0
bit 13-8 CP<1:0>: Code protection bits
(1)
5-4: 11 = Code protection off
10 = Upper half of program memory code protected
01 = Upper 3/4th of program memory code protected
00 = All memory is code protected
bit 7: Unimplemented: Read as '1'
bit 6: Reserved: Do not use
bit 3: PWRTE: Power-up Timer Enable bit
1 = PWRT disabled
0 = PWRT enabled
bit 2: WDTE: Watchdog Timer Enable bit
1 = WDT enabled
0 = WDT disabled
bit 1-0: FOSC1:FOSC0: Oscillator Selection bits
11 = RC oscillator
10 = HS oscillator
01 = XT oscillator
00 = LP oscillator
Note 1: All of the CP1:CP0 pairs have to be given the same value to enable the code protection scheme listed.
1997 Microchip Technology Inc. Preliminary DS40143B-page 37
PIC16C55X(A)
7.2 Oscillator Configurations
7.2.1 OSCILLATOR TYPES
The PIC16C55X(A) can be operated in four different
oscillator options. The user can program two
configuration bits (FOSC1 and FOSC0) to select one of
these four modes:
• LP Low Power Crystal
• XT Crystal/Resonator
• HS High Speed Crystal/Resonator
• RC Resistor/Capacitor
7.2.2 CRYSTAL OSCILLATOR / CERAMIC
RESONATORS
In XT, LP or HS modes a crystal or ceramic resonator
is connected to the OSC1 and OSC2 pins to establish
oscillation (Figure 7-2). The PIC16C55X(A) oscillator
design requires the use of a parallel cut crystal. Use of
a series cut crystal may give a frequency out of the
crystal manufacturers specifications. When in XT, LP or
HS modes, the device can have an external clock
source to drive the OSC1 pin (Figure 7-3).
FIGURE 7-2: CRYSTAL OPERATION
(OR CERAMIC RESONATOR)
(HS, XT OR LP OSC
CONFIGURATION)
FIGURE 7-3: EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
See Table 7-1 and Table 7-2 for recommended
values of C1 and C2.
Note: A series resistor may be required for
AT strip cut crystals.
C1
C2
XTAL
OSC2
RS
OSC1
RF
SLEEP
To internal logic
PIC16C55X(A)
see Note
Clock from
ext. system
PIC16C55X(A)
OSC1
OSC2
Open
TABLE 7-1: CAPACITOR SELECTION
FOR CERAMIC RESONATORS
(PRELIMINARY)
T ABLE 7-2: CAPACITOR SELECTION
FOR CRYSTAL OSCILLATOR
(PRELIMINARY)
Ranges Characterized:
Mode Freq OSC1(C1) OSC2(C2)
XT 455 kHz
2.0 MHz
4.0 MHz
22 - 100 pF
15 - 68 pF
15 - 68 pF
22 - 100 pF
15 - 68 pF
15 - 68 pF
HS 8.0 MHz
16.0 MHz
10 - 68 pF
10 - 22 pF
10 - 68 pF
10 - 22 pF
Higher capacitance increases the stability of the oscillator
but also increases the start-up time. These values are for
design guidance only. Since each resonator has its own
characteristics, the user should consult the resonator manufacturer for appropriate values of external components.
Resonators to be Characterized:
455 kHz Panasonic EFO-A455K04B ±0.3%
2.0 MHz Murata Erie CSA2.00MG ±0.5%
4.0 MHz Murata Erie CSA4.00MG ±0.5%
8.0 MHz Murata Erie CSA8.00MT ±0.5%
16.0 MHz Murata Erie CSA16.00MX ±0.5%
All resonators used did not have built-in capacitors.
Mode Freq OSC1(C1) OSC2(C2)
LP
32 kHz
200 kHz
68 - 100 pF
15 - 30 pF
68 - 100 pF
15 - 30 pF
XT
100 kHz
2 MHz
4 MHz
68 - 150 pF
15 - 30 pF
15 - 30 pF
150 - 200 pF
15 - 30 pF
15 - 30 pF
HS
8 MHz
10 MHz
20 MHz
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
Higher capacitance increases the stability of the oscillator
but also increases the start-up time. These values are for
design guidance only. Rs may be required in HS mode as
well as XT mode to avoid overdriving crystals with low drive
level specification. Since each crystal has its own
characteristics, the user should consult the crystal manufacturer for appropriate values of external components.
Crystals to be Characterized:
32.768 kHz Epson C-001R32.768K-A ± 20 PPM
100 kHz Epson C-2 100.00 KC-P ± 20 PPM
200 kHz STD XTL 200.000 kHz ± 20 PPM
2.0 MHz ECS ECS-20-S-2 ± 50 PPM
4.0 MHz ECS ECS-40-S-4 ± 50 PPM
10.0 MHz ECS ECS-100-S-4 ± 50 PPM
20.0 MHz ECS ECS-200-S-4 ± 50 PPM
PIC16C55X(A)
DS40143B-page 38 Preliminary 1997 Microchip Technology Inc.
7.2.3 EXTERNAL CRYSTAL OSCILLATOR
CIRCUIT
Either a pre-packaged oscillator can be used or a simple oscillator circuit with TTL gates can be built.
Prepackaged oscillators provide a wide operating
range and better stability. A well-designed crystal
oscillator will provide good performance with TTL
gates. Two types of crystal oscillator circuits can be
used; one with series resonance, or one with parallel
resonance.
Figure 7-4 shows implementation of a parallel resonant
oscillator circuit. The circuit is designed to use the
fundamental frequency of the crystal. The 74AS04
inverter performs the 180° phase shift that a parallel
oscillator requires. The 4.7 kΩ resistor provides the
negative feedback for stability. The 10 kΩ
potentiometers bias the 74AS04 in the linear region.
This could be used for external oscillator designs.
FIGURE 7-4: EXTERNAL PARALLEL
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
Figure 7-5 shows a series resonant oscillator circuit.
This circuit is also designed to use the fundamental
frequency of the crystal. The inverter performs a 180°
phase shift in a series resonant oscillator circuit. The
330 Ω resistors provide the negative feedback to bias
the inverters in their linear region.
FIGURE 7-5: EXTERNAL SERIES
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
20 pF
+5V
20 pF
10k
4.7k
10k
74AS04
XTAL
10k
74AS04
PIC16C55X(A)
CLK
IN
To other
Devices
330 Ω
74AS04
74AS04
PIC16C55X(A
)
CLKIN
To other
Devices
XTAL
330 Ω
74AS04
0.1 µF
7.2.4 RC OSCILLATOR
For timing insensitive applications the “RC” device
option offers additional cost savings. The RC oscillator
frequency is a function of the supply voltage, the
resistor (Rext) and capacitor (Cext) values, and the
operating temperature. In addition to this, the oscillator
frequency will vary from unit to unit due to normal
process parameter variation. Furthermore, the
difference in lead frame capacitance between package
types will also affect the oscillation frequency,
especially for low Cext values. The user also needs to
take into account variation due to tolerance of external
R and C components used. Figure 7-6 shows how the
R/C combination is connected to the PIC16C55X. For
Rext values below 2.2 kΩ, the oscillator operation may
become unstable, or stop completely. For very high
Rext values (e.g., 1 MΩ), the oscillator becomes
sensitive to noise, humidity and leakage. Thus, we
recommend to keep Rext between 3 kΩ and 100 kΩ.
Although the oscillator will operate with no external
capacitor (Cext = 0 pF), we recommend using values
above 20 pF for noise and stability reasons. With no or
small external capacitance, the oscillation frequency
can vary dramatically due to changes in external
capacitances, such as PCB trace capacitance or
package lead frame capacitance.
The oscillator frequency, divided by 4, is available on
the OSC2/CLKOUT pin, and can be used for test
purposes or to synchronize other logic (Figure 3-2 for
waveform).
FIGURE 7-6: RC OSCILLATOR MODE
OSC2/CLKOUT
Cext
Rext
V
DD
PIC16C55X(A)
OSC1
Fosc/4
Internal Clock
VDD
1997 Microchip Technology Inc. Preliminary DS40143B-page 39
PIC16C55X(A)
7.3 Reset
The PIC16C55X(A) differentiates between various
kinds of reset:
a) Power-on reset (POR)
b) MCLR
reset during normal operation
c) MCLR
reset during SLEEP
d) WDT reset (normal operation)
e) WDT wake-up (SLEEP)
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 Power-on reset, on MCLR
or WDT reset and
on MCLR
reset during SLEEP. They are not aff ected b y
a WDT wak e-up , since this is vie wed as the resumption
of normal operation. T
O and PD bits are set or cleared
differently in different reset situations as indicated in
Table 7-4. These bits are used in software to determine
the nature of the reset. See Table 7-6 for a full description of reset states of all registers.
A simplified block diagram of the on-chip reset circuit is
shown in Figure 7-7.
The MCLR
reset path has a noise filter to detect and
ignore small pulses. See Table 10-4 for pulse width
specification.
FIGURE 7-7: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
S
R
Q
External
Reset
MCLR/
V
DD
OSC1/
WDT
Module
V
DD rise
detect
OST/PWRT
On-chip
(1)
RC OSC
WDT
Time-out
Power-on Reset
OST
PWRT
Chip_Reset
10-bit Ripple-counter
Reset
Enable OST
Enable PWRT
SLEEP
See Table 7-3 for time-out situations.
Note 1: This is a separate oscillator from the RC oscillator of the CLKIN pin.
CLKIN
Pin
VPP Pin
10-bit Ripple-counter
PIC16C55X(A)
DS40143B-page 40 Preliminary 1997 Microchip Technology Inc.
7.4 Power-on Reset (POR), Power-up
Timer (PWRT), Oscillator Start-up
Timer (OST)
7.4.1 POWER-ON RESET (POR)
A Power-on Reset pulse is generated on-chip when
V
DD rise is detected (in the range of 1.6 V – 1.8 V). To
take advantage of the POR, just tie the MCLR
pin
directly (or through a resistor) to V
DD. This will eliminate
external RC components usually needed to create
Power-on Reset. A maximum rise time for V
DD is
required. See Electrical Specifications for details.
The POR circuit does not produce internal reset when
V
DD declines.
When the device starts normal operation (exits the
reset condition), device operating parameters (voltage ,
frequency, temperature, etc.) must be met to ensure
operation. If these conditions are not met, the device
must be held in reset until the operating conditions are
met.
For additional information, refer to Application Note
AN607 “Power-up Trouble Shooting”.
7.4.2 POWER-UP TIMER (PWRT)
The Power-up Timer provides a fixed 72 ms (nominal)
time-out on power-up only, from POR. The Power-up
Timer operates on an internal RC oscillator. The chip is
kept in reset as long as PWRT is active. The PWRT
delay allows the V
DD to rise to an acceptable level. A
configuration bit, PW
RTE can disable (if set) or enable
(if cleared or programmed) the Power-up Timer. The
Power-Up Time delay will vary from chip to chip and
due to V
DD, temperature and process variation. See
DC parameters for details.
7.4.3 OSCILLATOR START-UP TIMER (OST)
The Oscillator Start-Up Timer (OST) provides a 1024
oscillator cycle (from OSC1 input) delay after the
PWRT delay is over. This ensures that the crystal
oscillator or resonator has started and stabilized.
The OST time-out is invoked only for XT, LP and HS
modes and only on power-on reset or wake-up from
SLEEP.
7.4.4 TIME-OUT SEQUENCE
On power-up, the time-out sequence is as f ollows: First
PWRT time-out is inv ok ed after POR has expired, then
OST is activated. The total time-out will vary based on
oscillator configuration and P
WRTE bit status. For
example, in RC mode with PW
RTE bit erased (PWRT
disabled), there will be no time-out at all. Figure 7-8,
Figure 7-9 and Figure 7-10 depict time-out sequences.
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 7-9). This is useful for testing purposes or
to synchronize more than one PIC16C55X device operating in parallel.
Table 7-5 shows the reset conditions for some special
registers, while T ab le 7-6 shows the reset conditions for
all the registers.
1997 Microchip Technology Inc. Preliminary DS40143B-page 41
PIC16C55X(A)
7.4.5 POWER CONTROL/STATUS REGISTER
(PCON)
Bit1 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 must have occurred (V
DD may have
gone too low).
TABLE 7-3: TIME-OUT IN VARIOUS SITUATIONS
TABLE 7-4: STATUS BITS AND THEIR SIGNIFICANCE
Oscillator Configuration
Power-up
Wake-up from
SLEEP
PWR
TE = 0 PWRTE = 1
XT, HS, LP 72 ms + 1024 TOSC 1024 TOSC 1024 TOSC
RC 72 ms — —
POR
TO PD
0 1 1
Power-on-reset
0 0 X
Illegal, TO is set on POR
0 X 0
Illegal, PD is set on POR
1 0 1
WDT Reset
1 0 0
WDT Wake-up
1 1 1
MCLR reset during normal operation
1 1 0
MCLR reset during SLEEP
PIC16C55X(A)
DS40143B-page 42 Preliminary 1997 Microchip Technology Inc.
TABLE 7-5: INITIALIZATION CONDITION FOR SPECIAL REGISTERS
TABLE 7-6: INITIALIZATION CONDITION FOR REGISTERS
Condition
Program
Counter
STATUS
Register
PCON
Register
Power-on Reset 000h
0001 1xxx ---- --0-
MCLR reset during normal operation 000h
0001 1uuu ---- --u-
MCLR reset during SLEEP 000h
0001 0uuu ---- --u-
WDT reset 000h
0000 1uuu ---- --u-
WDT Wake-up PC + 1
uuu0 0uuu ---- --u-
Interrupt Wake-up from SLEEP PC + 1
(1)
uuu1 0uuu ---- --u-
Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’.
Note 1: When the wake-up is due to an interrupt and global enable bit, GIE is set, the PC is loaded with the interrupt vector
(0004h) after execution of PC+1.
Register Address Power-on Reset
• MCLR Reset during
normal operation
• MCLR Reset during
SLEEP
• WDT Reset
• Wake up from SLEEP
through interrupt
• Wake up from SLEEP
through WDT time-out
W -
xxxx xxxx uuuu uuuu uuuu uuuu
INDF 00h
- - -
TMR0 01h
xxxx xxxx uuuu uuuu uuuu uuuu
PCL 02h
0000 0000 0000 0000
PC + 1
(2)
STATUS 03h
0001 1xxx
000q quuu
(3)
uuuq quuu
(3)
FSR 04h
xxxx xxxx uuuu uuuu uuuu uuuu
PORTA 05h
---x xxxx ---u uuuu ---u uuuu
PORTB 06h
xxxx xxxx uuuu uuuu uuuu uuuu
PCLATH 0Ah
---0 0000 ---0 0000 ---u uuuu
INTCON 0Bh
0000 000x 0000 000x
uuuu uuuu
(1)
OPTION 81h
1111 1111 1111 1111 uuuu uuuu
TRISA 85h
---1 1111 ---1 1111 ---u uuuu
TRISB 86h
1111 1111 1111 1111 uuuu uuuu
PCON 8Eh
---- --0-
---- --u-
---- --u-
Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’,q = value depends on condition.
Note 1: One or more bits in INTCON will be affected (to cause wake-up).
2: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt
vector (0004h).
3: See Table 7-5 for reset value for specific condition.
1997 Microchip Technology Inc. Preliminary DS40143B-page 43
PIC16C55X(A)
FIGURE 7-8: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1
FIGURE 7-9: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2
FIGURE 7-10: TIME-OUT SEQUENCE ON POWER-UP (MCLR
TIED TO VDD): CASE 3
TPWRT
TOST
VDD
MCLR
INTERNAL POR
PWR
T TIME-OUT
OST TIME-OUT
INTERNAL RESET
VDD
MCLR
INTERNAL POR
PWR
T TIME-OUT
OST TIME-OUT
INTERNAL RESET
TPWRT
TOST
TPWRT
TOST
VDD
MCLR
INTERNAL POR
PWR
T TIME-OUT
OST TIME-OUT
INTERNAL RESET
PIC16C55X(A)
DS40143B-page 44 Preliminary 1997 Microchip Technology Inc.
FIGURE 7-11: EXTERNAL POWER-ON
RESET CIRCUIT (FOR SLOW
VDD POWER-UP)
Note 1: External power-on reset circuit is required
only if V
DD power-up slope is too slow.
The diode D helps discharge the capacitor quickly when V
DD powers down.
2: < 40 kΩ is recommended to make sure
that voltage drop across R does not violate the device’s electrical specification.
3: R1 = 100Ω to 1 kΩ will limit any current
flowing into MCLR
from external capaci-
tor C in the event of MCLR
/VPP pin breakdown due to Electrostatic Discharge
(ESD) or Electrical Overstress (EOS).
C
R1
R
D
V
DD
MCLR
PIC16C55X(A)
VDD
1997 Microchip Technology Inc. Preliminary DS40143B-page 45
PIC16C55X(A)
7.5 Interrupts
The PIC16C55X(A) has 3 sources of interrupt:
• External interrupt RB0/INT
• TMR0 overflow interrupt
• PortB change interrupts (pins RB7:RB4)
The interrupt control register (INTCON) records
individual interrupt requests in flag bits. It also has
individual and global interrupt enable bits.
A global interrupt enable bit, GIE (INTCON<7>)
enables (if set) all un-masked interrupts or disables (if
cleared) all interrupts. Individual interrupts can be
disabled through their corresponding enable bits in
INTCON register. GIE is cleared on reset.
The “return from interrupt” instruction,
RETFIE, exits
the interrupt routine as well as sets the GIE bit, which
re-enables RB0/INT interrupts.
The INT pin interrupt, the RB port change interrupt and
the TMR0 overflow interrupt flags are contained in the
INTCON register.
When an interrupt is responded to, the GIE is cleared
to disable any further interrupt, the return address is
pushed into the stack and the PC is loaded with 0004h.
Once in the interrupt service routine the source(s) of
the interrupt can be determined by polling the interrupt
flag bits. The interrupt flag bit(s) must be cleared in software before re-enabling interrupts to avoid RB0/INT
recursive interrupts.
For external interrupt events, such as the INT pin or
PORTB change interrupt, the interrupt latency will be
three or four instruction cycles. The exact latency
depends when the interrupt event occurs (Figure 7-13).
The latency is the same for one or two cycle
instructions. Once in the interrupt service routine the
source(s) of the interrupt can be determined by polling
the interrupt flag bits. The interrupt flag bit(s) must be
cleared in software before re-enabling interrupts to
avoid multiple interrupt requests. Individual interrupt
flag bits are set regardless of the status of their
corresponding mask bit or the GIE bit.
Note 1: Individual interrupt flag bits are set
regardless of the status of their
corresponding mask bit or the GIE bit.
2: When an instruction that clears the GIE
bit is executed, any interrupts that were
pending for execution in the next cycle
are ignored. The CPU will execute a
NOP in the cycle immediately following
the instruction which clears the GIE bit.
The interrupts which were ignored are
still pending to be serviced when the GIE
bit is set again.
FIGURE 7-12: INTERRUPT LOGIC
RBIF
RBIE
T0IF
T0IE
INTF
INTE
GIE
Wake-up
(If in SLEEP mode)
Interrupt
to CPU
PIC16C55X(A)
DS40143B-page 46 Preliminary 1997 Microchip Technology Inc.
7.5.1 RB0/INT INTERRUPT
An external interrupt on RB0/INT pin is edge triggered:
either rising if INTEDG bit (OPTION<6>) is set, or falling if INTEDG bit is clear. When a valid edge appears
on the RB0/INT pin, the INTF bit (INTCON<1>) is set.
This interrupt can be disabled by clearing the INTE
control bit (INTCON<4>). The INTF bit must be cleared
in software in the interrupt service routine before
re-enabling this interrupt. The RB0/INT interrupt can
wake-up the processor from SLEEP, if the INTE bit was
set prior to going into SLEEP. The status of the GIE bit
decides whether or not the processor branches to the
interrupt vector following wake-up. See Section 7.8 for
details on SLEEP and Figure 7-16 for timing of
wake-up from SLEEP through RB0/INT interrupt.
7.5.2 TMR0 INTERRUPT
An overflow (FFh → 00h) in the TMR0 register will
set the T0IF (INTCON<2>) bit. The interrupt can
be enabled/disabled by setting/clearing T0IE
(INTCON<5>) bit. For operation of the Timer0 module,
see Section 6.0.
7.5.3 PORTB INTERRUPT
An input change on PORTB <7:4> sets the RBIF
(INTCON<0>) bit. The interrupt can be enabled/disabled by setting/clearing the RBIE (INTCON<4>) bit.
For operation of PORTB (Section 5.2).
Note: If a change on the I/O pin should occur
when the read operation is being executed
(start of the Q2 cycle), then the RBIF interrupt flag may get set.
FIGURE 7-13: INT PIN INTERRUPT TIMING
Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4
OSC1
CLKOUT
INT pin
INTF flag
(INTCON<1>)
GIE bit
(INTCON<7>)
INSTR
UCTION FLOW
PC
Instruction
fetched
Instruction
executed
Interrupt Latency
PC PC+1 PC+1 0004h 0005h
Inst (0004h)
Inst (0005h)
Dummy Cycle
Inst (PC)
Inst (PC+1)
Inst (PC-1)
Inst (0004h)
Dummy Cycle
Inst (PC)
—
1
4
5
1
Note
1: INTF flag is sampled here (every Q1).
2: Interrupt latency = 3-4 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 RC oscillator mode.
4: For minimum width of INT pulse, refer to AC specs.
5: INTF is enabled to be set anytime during the Q4-Q1 cycles.
2
3
1997 Microchip Technology Inc. Preliminary DS40143B-page 47
PIC16C55X(A)
7.6 Context Saving During Interrupts
During an interrupt, only the return PC value is saved
on the stack. Typically, users may wish to sa ve key registers during an interrupt, e.g. W register and STATUS
register. This will have to be implemented in software.
Example 7-1 stores and restores the STATUS and W
registers. The user register, W_TEMP, must be defined
in both banks and must be defined at the same offset
from the bank base address (i.e., W_TEMP is defined
at 0x20 in Bank 0 and it must also be defined at 0xA0
in Bank 1). The user register, STATUS_TEMP, must be
defined in Bank 0. The Example 7-1:
• Stores the W register
• Stores the STATUS register in Bank 0
• Executes the ISR code
• Restores the STATUS (and bank select bit
register)
• Restores the W register
EXAMPLE 7-1: SAVING THE STATUS AND
W REGISTERS IN RAM
MOVWF W_TEMP ;copy W to temp register,
;could be in either bank
SWAPF STATUS,W ;swap status to be saved into W
BCF STATUS,RP0 ;change to bank 0 regardless
;of current bank
MOVWF STATUS_TEMP ;save status to bank 0
;register
:
: (ISR)
:
SWAPF STATUS_TEMP,W ;swap STATUS_TEMP register
;into W, sets bank to original
;state
MOVWF STATUS ;move W into STATUS register
SWAPF W_TEMP,F ;swap W_TEMP
SWAPF W_TEMP,W ;swap W_TEMP into W
7.7 Watchdog Timer (WDT)
The watchdog timer is a free running on-chip RC oscillator which does not require any external components.
This RC oscillator is separate from the RC oscillator of
the CLKIN pin. That means that the WDT will run, even
if the clock on the OSC1 and OSC2 pins of the device
has been stopped, for example, by execution of a
SLEEP instruction. During normal operation, a WDT
time-out generates a device RESET. If the device is in
SLEEP mode, a WDT time-out causes the device to
wake-up and continue with normal operation. The WDT
can be permanently disabled by programming the configuration bit WDTE as clear (Section 7.1).
7.7.1 WDT PERIOD
The WDT has a nominal time-out period of 18 ms, (with
no prescaler). The time-out periods vary with temperature, V
DD
and process variations from part to part (see
DC specs). If longer time-out periods are desired, a
prescaler with a division ratio of up to 1:128 can be
assigned to the WDT under software control by writing
to the OPTION register. Thus, time-out periods up to
2.3 seconds can be realized.
The
CLRWDT and SLEEP instructions clear the WDT
and the postscaler, if assigned to the WDT, and prevent
it from timing out and generating a device RESET.
The T
O bit in the STATUS register will be cleared upon
a Watchdog Timer time-out.
7.7.2 WDT PROGRAMMING CONSIDERATIONS
It should also be taken in account that under worst case
conditions (V
DD = Min., Temperature = Max., max.
WDT prescaler) it may take several seconds before a
WDT time-out occurs.
PIC16C55X(A)
DS40143B-page 48 Preliminary 1997 Microchip Technology Inc.
FIGURE 7-14: WATCHDOG TIMER BLOCK DIAGRAM
FIGURE 7-15: SUMMARY OF WATCHDOG TIMER REGISTERS
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
2007h Config. bits
— + CP1 CP0 PWRTE WDTE FOSC1 FOSC0
81h OPTION
RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0
Legend: Shaded cells are not used by the Watchdog Timer.
— = Unimplemented location, read as ‘0’.
+ = Reserved for future use.
From TMR0 Clock Source
(Figure 6-6)
To TMR0 (Figure 6-6)
Postscaler
Watchdog
Timer
M
U
X
PSA
8 - to -1 MUX
PSA
WDT
Time-out
1
0
0
1
WDT
Enable Bit
PS<2:0>
•
•
Note: T0SE, T0CS, PSA, PS0-PS2 are bits in the OPTION register.
8
MUX
1997 Microchip Technology Inc. Preliminary DS40143B-page 49
PIC16C55X(A)
7.8 Power-Down Mode (SLEEP)
The Power-down mode is entered by executing a
SLEEP instruction.
If enabled, the Watchdog Timer will be cleared but
keeps running, the PD
bit in the STATUS register is
cleared, the T
O bit is set, and the oscillator driver is
turned off. The I/O ports maintain the status they had,
before
SLEEP was executed (driving high, low, or
hi-impedance).
For lowest current consumption in this mode, all I/O
pins should be either at V
DD, or VSS, with no external
circuitry drawing current from the I/O pin. I/O pins that
are hi-impedance inputs should be pulled high or low
externally to avoid switching currents caused by floating inputs. The T0CKI input should also be at V
DD or
V
SS 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 (VIHMC).
7.8.1 WAKE-UP FROM SLEEP
The device can wake-up from SLEEP through one of
the following events:
1. External reset input on MCLR
pin
2. Watchdog Timer Wake-up (if WDT was enabled)
3. Interrupt from RB0/INT pin or RB Port change
The first event will cause a device reset. The two latter
events are considered a continuation of program execution. The T
O and PD bits in the STATUS register can
be used to determine the cause of device reset. PD
bit, which is set on power-up is cleared when SLEEP is
invoked. T
O bit is cleared if WDT Wake-up occurred.
When the
SLEEP instruction is being executed, the
next instruction (PC + 1) is pre-fetched. For the device
to wake-up through an interrupt event, the corresponding interrupt enable bit must be set (enabled). Wak e-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 and then branches to the inter-
rupt address (0004h). In cases where the execution of
the instruction following
SLEEP is not desirable, the
user should have an
NOP after the SLEEP instruction.
The WDT is cleared when the device wakes-up from
sleep, regardless of the source of wake-up.
Note: It should be noted that a RESET generated
by a WDT time-out does not drive MCLR
pin low.
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 wakeup from sleep. The sleep
instruction is completely executed.
FIGURE 7-16: 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
OSC1
CLKOUT(4)
INT pin
INTF flag
(INTCON<1>)
GIE bit
(INTCON<7>)
INSTR
UCTION FLOW
PC
Instruction
fetched
Instruction
executed
PC PC+1 PC+2
Inst(PC) = SLEEP
Inst(PC - 1)
Inst(PC + 1)
SLEEP
Processor in
SLEEP
Interrupt Latency
(Note 2)
Inst(PC + 2)
Inst(PC + 1)
Inst(0004h)
Inst(0005h)
Inst(0004h)
Dummy cycle
PC + 2 0004h 0005h
Dummy cycle
T
OST(2)
PC+2
Note 1: XT, HS or LP oscillator mode assumed.
2: T
OST = 1024TOSC (drawing not to scale) This delay will not be there for RC osc mode.
3: GIE = '1' assumed. In this case after wake- up, the processor jumps to the interrupt routine. If GIE = '0', execution will continue in-line.
4: CLKOUT is not available in these osc modes, but shown here for timing reference.
PIC16C55X(A)
DS40143B-page 50 Preliminary 1997 Microchip Technology Inc.
7.9 Code Protection
If the code protection bit(s) have not been
programmed, the on-chip program memory can be
read out for verification purposes.
7.10 ID Locations
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. Only the
least significant 4 bits of the ID locations are used.
Note: Microchip does not recommend code
protecting windowed devices.
7.11 In-Circuit Serial Programming™
The PIC16C55X(A) microcontrollers can be serially
programmed while in the end application circuit. This is
simply done with two lines for clock and data, and three
other lines for power, ground, and the programming
voltage. This allows customers to manufacture boards
with unprogrammed devices, and then program the
microcontroller just before shipping the product. This
also allows the most recent firmware or a custom
firmware to be programmed.
The device is placed into a program/verify mode by
holding the RB6 and RB7 pins low while raising the
MCLR
(VPP) pin from VIL to VIHH (see programming
specification). RB6 becomes the programming clock
and RB7 becomes the programming data. Both RB6
and RB7 are Schmitt Trigger inputs in this mode.
After reset, to place the device into programming/verify
mode, the program counter (PC) is at location 00h. A
6-bit command is then supplied to the device.
Depending on the command, 14-bits of program data
are then supplied to or from the device, depending if the
command was a load or a read. F or complete details of
serial programming, please refer to the PIC16C6X/7X
Programming Specifications (Literature #DS30228).
A typical in-circuit serial programming connection is
shown in Figure 7-17.
FIGURE 7-17: TYPICAL IN-CIRCUIT SERIAL
PROGRAMMING
CONNECTION
External
Connector
Signals
To Normal
Connections
To Normal
Connections
PIC16C55X(A)
V
DD
VSS
MCLR/VPP
RB6
RB7
+5V
0V
VPP
CLK
Data I/O
VDD
1997 Microchip Technology Inc. Preliminary DS40143B-page 51
PIC16C55X(A)
8.0 INSTRUCTION SET SUMMARY
Each PIC16C55X(A) 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 PIC16C55X(A)
instruction set summary in Table 8-2 lists byte-ori-
ented, bit-oriented, and literal and control opera-
tions. Table 8-1 shows the opcode field descriptions.
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.
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 number of the bit affected
by the operation, while 'f' represents the number of the
file in which the bit is located.
For literal and control operations, 'k' represents an
eight or eleven bit constant or literal value.
TABLE 8-1: OPCODE FIELD
DESCRIPTIONS
Field Description
f Register file address (0x00 to 0x7F)
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.
d Destination select; d = 0: store result in W,
d = 1: store result in file register f.
Default is d = 1
label Label name
TOS Top of Stack
PC Program Counter
PCLATH
Program Counter High Latch
GIE Global Interrupt Enable bit
WDT Watchdog Timer/Counter
TO Time-out bit
PD Power-down bit
dest Destination either the W register or the specified
register file location
[ ] Options
( )
Contents
→
Assigned to
< >
Register bit field
∈
In the set of
i
talics
User defined term (font is courier)
The instruction set is highly orthogonal and is grouped
into three basic categories:
• Byte-oriented operations
• Bit-oriented operations
• Literal and control operations
All instructions are executed within one single
instruction cycle, unless a conditional test is true or the
program counter is changed as a result of an
instruction. In this case, the execution takes two
instruction cycles with the second cycle executed as a
NOP. One instruction cycle consists of four oscillator
periods. Thus, for an oscillator frequency of 4 MHz, the
normal instruction execution time is 1 µs. If a
conditional test is true or the program counter is
changed as a result of an instruction, the instruction
execution time is 2 µs.
Table 8-1 lists the instructions recognized by the
MPASM assembler.
Figure 8-1 shows the three general formats that the
instructions can have.
All examples use the following format to represent a
hexadecimal number:
0xhh
where h signifies a hexadecimal digit.
FIGURE 8-1: GENERAL FORMAT FOR
INSTRUCTIONS
Note: To maintain upward compatibility with
future PICmicro™ products, do not use
the
OPTION and TRIS instructions.
Byte-oriented file register operations
13 8 7 6 0
d = 0 for destination W
OPCODE d f (FILE #)
d = 1 for destination f
f = 7-bit file register address
Bit-oriented file register operations
13 10 9 7 6 0
OPCODE b (BIT #) f (FILE #)
b = 3-bit bit address
f = 7-bit file register address
Literal and control operations
13 8 7 0
OPCODE k (literal)
k = 8-bit immediate value
13 11 10 0
OPCODE k (literal)
k = 11-bit immediate value
General
CALL and GOTO instructions only
PIC16C55X(A)
DS40143B-page 52 Preliminary 1997 Microchip Technology Inc.
TABLE 8-2: PIC16C55X(A) INSTRUCTION SET
Mnemonic,
Operands
Description Cycles 14-Bit Opcode Status
Affected
Notes
MSb LSb
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
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
0111
0101
0001
0001
1001
0011
1011
1010
1111
0100
1000
0000
0000
1101
1100
0010
1110
0110
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
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
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 (2)
1 (2)
01
01
01
01
00bb
01bb
10bb
11bb
bfff
bfff
bfff
bfff
ffff
ffff
ffff
ffff
1,2
1,2
3
3
LITERAL AND CONTROL OPERATIONS
ADDLW
ANDLW
CALL
CLRWDT
GOTO
IORLW
MOVLW
RETFIE
RETLW
RETURN
SLEEP
SUBLW
XORLW
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
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
C,DC,Z
Z
T
O,PD
Z
TO,PD
C,DC,Z
Z
Note 1: When an I/O register is modified as a function of itself ( e.g., MOVF PORTB, 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'.
2: If this instruction is ex ecuted on the TMR0 register (and, where applicable, d = 1), the prescaler will be cleared if assigned
to the Timer0 Module.
3: If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is
executed as a NOP.
1997 Microchip Technology Inc. Preliminary DS40143B-page 53
PIC16C55X(A)
8.1 Instruction Descriptions
ADDLW Add Literal and W
Syntax: [
label
] ADDLW k
Operands: 0 ≤ k ≤ 255
Operation: (W) + k → (W)
Status Affected: C, DC, Z
Encoding:
11 111x kkkk kkkk
Description:
The contents of the W register are
added to the eight bit literal 'k' and the
result is placed in the W register
.
Words: 1
Cycles: 1
Example
ADDLW 0x15
Before Instruction
W = 0x10
After Instruction
W = 0x25
ADDWF Add W and f
Syntax: [
label
] ADDWF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (W) + (f) → (dest)
Status Affected: C, DC, Z
Encoding:
00 0111 dfff ffff
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'
.
Words: 1
Cycles: 1
Example
ADDWF FSR, 0
Before Instruction
W = 0x17
FSR = 0xC2
After Instruction
W = 0xD9
FSR = 0xC2
ANDLW AND Literal with W
Syntax: [
label
] ANDLW k
Operands: 0 ≤ k ≤ 255
Operation: (W) .AND. (k) → (W)
Status Affected: Z
Encoding:
11 1001 kkkk kkkk
Description:
The contents of W register are
AND’ed with the eight bit literal 'k'. The
result is placed in the W register
.
Words: 1
Cycles: 1
Example
ANDLW 0x5F
Before Instruction
W = 0xA3
After Instruction
W = 0x03
ANDWF AND W with f
Syntax: [
label
] ANDWF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (W) .AND. (f) → (dest)
Status Affected: Z
Encoding:
00 0101 dfff ffff
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'
.
Words: 1
Cycles: 1
Example
ANDWF FSR, 1
Before Instruction
W = 0x17
FSR = 0xC2
After Instruction
W = 0x17
FSR = 0x02
PIC16C55X(A)
DS40143B-page 54 Preliminary 1997 Microchip Technology Inc.
BCF Bit Clear f
Syntax: [
label
] BCF f,b
Operands: 0 ≤ f ≤ 127
0 ≤ b ≤ 7
Operation: 0 → (f<b>)
Status Affected: None
Encoding:
01 00bb bfff ffff
Description: Bit 'b' in register 'f' is cleared.
Words: 1
Cycles: 1
Example
BCF FLAG_REG, 7
Before Instruction
FLAG_REG = 0xC7
After Instruction
FLAG_REG = 0x47
BSF Bit Set f
Syntax: [
label
] BSF f,b
Operands: 0 ≤ f ≤ 127
0 ≤ b ≤ 7
Operation: 1 → (f<b>)
Status Affected: None
Encoding:
01 01bb bfff ffff
Description:
Bit 'b' in register 'f' is set.
Words: 1
Cycles: 1
Example
BSF FLAG_REG, 7
Before Instruction
FLAG_REG = 0x0A
After Instruction
FLAG_REG = 0x8A
BTFSC Bit Test, Skip if Clear
Syntax: [
label
] BTFSC f,b
Operands: 0 ≤ f ≤ 127
0 ≤ b ≤ 7
Operation: skip if (f<b>) = 0
Status Affected: None
Encoding:
01 10bb bfff ffff
Description:
If bit 'b' in register 'f' is '0' then the next
instruction is skipped.
If bit 'b' is '0' then the next instruction
fetched during the current instruction
execution is discarded, and a NOP is
executed instead, making this a
two-cycle instruction
.
Words: 1
Cycles: 1(2)
Example
HERE
FALSE
TRUE
BTFSC
GOTO
•
•
•
FLAG,1
PROCESS_CODE
Before Instruction
PC = address HERE
After Instruction
if FLAG<1> = 0,
PC = address TRUE
if FLAG<1>=1,
PC = address FALSE
1997 Microchip Technology Inc. Preliminary DS40143B-page 55
PIC16C55X(A)
BTFSS Bit Test f, Skip if Set
Syntax: [
label
] BTFSS f,b
Operands: 0 ≤ f ≤ 127
0 ≤ b < 7
Operation: skip if (f<b>) = 1
Status Affected: None
Encoding:
01 11bb bfff ffff
Description:
If bit 'b' in register 'f' is '1' then the next
instruction is skipped.
If bit 'b' is '1', then the next instruction
fetched during the current instruction
execution, is discarded and a NOP is
executed instead, making this a
two-cycle instruction.
Words: 1
Cycles: 1(2)
Example
HERE
FALSE
TRUE
BTFSC
GOTO
•
•
•
FLAG,1
PROCESS_CODE
Before Instruction
PC = address HERE
After Instruction
if FLAG<1> = 0,
PC = address FALSE
if FLAG<1> = 1,
PC = address TRUE
CALL Call Subroutine
Syntax: [
label
] CALL k
Operands: 0 ≤ k ≤ 2047
Operation: (PC)+ 1→ TOS,
k → PC<10:0>,
(PCLATH<4:3>) → PC<12:11>
Status Affected: None
Encoding:
10 0kkk kkkk kkkk
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.
Words: 1
Cycles: 2
Example
HERE CALL THERE
Before Instruction
PC = Address HERE
After Instruction
PC = Address THERE
TOS= Address HERE+1
CLRF Clear f
Syntax: [
label
] CLRF f
Operands: 0 ≤ f ≤ 127
Operation: 00h → (f)
1 → Z
Status Affected: Z
Encoding:
00 0001 1fff ffff
Description:
The contents of register 'f' are cleared
and the Z bit is set.
Words: 1
Cycles: 1
Example
CLRF FLAG_REG
Before Instruction
FLAG_REG = 0x5A
After Instruction
FLAG_REG = 0x00
Z = 1
CLRW Clear W
Syntax: [
label
] CLRW
Operands: None
Operation: 00h → (W)
1 → Z
Status Affected: Z
Encoding:
00 0001 0xxx xxxx
Description:
W register is cleared. Zero bit (Z) is
set.
Words: 1
Cycles: 1
Example
CLRW
Before Instruction
W = 0x5A
After Instruction
W = 0x00
Z = 1
PIC16C55X(A)
DS40143B-page 56 Preliminary 1997 Microchip Technology Inc.
CLRWDT Clear Watchdog Timer
Syntax: [
label
] CLRWDT
Operands: None
Operation: 00h → WDT
0 → WDT prescaler,
1 → T
O
1 → PD
Status Affected: TO, PD
Encoding:
00 0000 0110 0100
Description:
CLRWDT instruction resets the
Watchdog Timer. It also resets the
prescaler of the WDT. Status bits TO
and PD are set.
Words: 1
Cycles: 1
Example
CLRWDT
Before Instruction
WDT counter = ?
After Instruction
WDT counter = 0x00
WDT prescaler= 0
TO = 1
PD = 1
COMF Complement f
Syntax: [
label
] COMF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f
) → (dest)
Status Affected: Z
Encoding:
00 1001 dfff ffff
Description:
The contents of register 'f' are
complemented. If 'd' is 0 the result is
stored in W. If 'd' is 1 the result is
stored back in register 'f'.
Words: 1
Cycles: 1
Example
COMF REG1,0
Before Instruction
REG1 = 0x13
After Instruction
REG1 = 0x13
W = 0xEC
DECF Decrement f
Syntax: [
label
] DECF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f) - 1 → (dest)
Status Affected: Z
Encoding:
00 0011 dfff ffff
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'
.
Words: 1
Cycles: 1
Example
DECF CNT, 1
Before Instruction
CNT = 0x01
Z = 0
After Instruction
CNT = 0x00
Z = 1
DECFSZ Decrement f, Skip if 0
Syntax: [
label
] DECFSZ f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f) - 1 → (dest); skip if result = 0
Status Affected: None
Encoding:
00 1011 dfff ffff
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 0, the next instruction,
which is already fetched, is discarded. A
NOP is executed instead making it a
two-cycle instruction.
Words: 1
Cycles: 1(2)
Example
HERE DECFSZ CNT, 1
GOTO LOOP
CONTINUE •
•
•
Before Instruction
PC = address HERE
After Instruction
CNT = CNT - 1
if CNT = 0,
PC = address CONTINUE
if CNT ≠ 0,
PC = address HERE+1
1997 Microchip Technology Inc. Preliminary DS40143B-page 57
PIC16C55X(A)
GOTO Unconditional Branch
Syntax: [
label
] GOTO k
Operands: 0 ≤ k ≤ 2047
Operation: k → PC<10:0>
PCLATH<4:3> → PC<12:11>
Status Affected: None
Encoding:
10 1kkk kkkk kkkk
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.
Words: 1
Cycles: 2
Example
GOTO THERE
After Instruction
PC = Address THERE
INCF Increment f
Syntax: [
label
] INCF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f) + 1 → (dest)
Status Affected: Z
Encoding:
00 1010 dfff ffff
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'.
Words: 1
Cycles: 1
Example
INCF CNT, 1
Before Instruction
CNT = 0xFF
Z = 0
After Instruction
CNT = 0x00
Z = 1
INCFSZ Increment f, Skip if 0
Syntax: [
label
] INCFSZ f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f) + 1 → (dest), skip if result = 0
Status Affected: None
Encoding:
00 1111 dfff ffff
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 0, the next instruction,
which is already fetched, is discarded.
A NOP is executed instead making it
a two-cycle instruction
.
Words: 1
Cycles: 1(2)
Example
HERE INCFSZ CNT, 1
GOTO LOOP
CONTINUE •
•
•
Before Instruction
PC = address HERE
After Instruction
CNT = CNT + 1
if CNT= 0,
PC = address CONTINUE
if CNT≠ 0,
PC = address HERE +1
IORLW Inclusive OR Literal with W
Syntax: [
label
] IORLW k
Operands: 0 ≤ k ≤ 255
Operation: (W) .OR. k → (W)
Status Affected: Z
Encoding:
11 1000 kkkk kkkk
Description:
The contents of the W register is
OR’ed with the eight bit literal 'k'. The
result is placed in the W register
.
Words: 1
Cycles: 1
Example
IORLW 0x35
Before Instruction
W = 0x9A
After Instruction
W = 0xBF
Z = 1
PIC16C55X(A)
DS40143B-page 58 Preliminary 1997 Microchip Technology Inc.
IORWF Inclusive OR W with f
Syntax: [
label
] IORWF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (W) .OR. (f) → (dest)
Status Affected: Z
Encoding:
00 0100 dfff ffff
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'.
Words: 1
Cycles: 1
Example
IORWF RESULT, 0
Before Instruction
RESULT = 0x13
W = 0x91
After Instruction
RESULT = 0x13
W = 0x93
Z = 1
MOVLW Move Literal to W
Syntax: [
label
] MOVLW k
Operands: 0 ≤ k ≤ 255
Operation: k → (W)
Status Affected: None
Encoding:
11 00xx kkkk kkkk
Description:
The eight bit literal 'k' is loaded into W
register
. The don’t cares will assemble
as 0’s.
Words: 1
Cycles: 1
Example
MOVLW 0x5A
After Instruction
W = 0x5A
MOVF Move f
Syntax: [
label
] MOVF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f) → (dest)
Status Affected: Z
Encoding:
00 1000 dfff ffff
Description:
The contents of register f is moved to
a destination dependant 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.
Words: 1
Cycles: 1
Example
MOVF FSR, 0
After Instruction
W = value in FSR register
Z = 1
MOVWF Move W to f
Syntax: [
label
] MOVWF f
Operands: 0 ≤ f ≤ 127
Operation: (W) → (f)
Status Affected: None
Encoding:
00 0000 1fff ffff
Description:
Move data from W register to register
'f'
.
Words: 1
Cycles: 1
Example
MOVWF OPTION
Before Instruction
OPTION = 0xFF
W = 0x4F
After Instruction
OPTION = 0x4F
W = 0x4F
1997 Microchip Technology Inc. Preliminary DS40143B-page 59
PIC16C55X(A)
NOP No Operation
Syntax: [
label
] NOP
Operands: None
Operation: No operation
Status Affected: None
Encoding:
00 0000 0xx0 0000
Description:
No operation.
Words: 1
Cycles: 1
Example
NOP
OPTION Load Option Register
Syntax: [
label
] OPTION
Operands: None
Operation: (W) → OPTION
Status Affected: None
Encoding:
00 0000 0110 0010
Description:
The contents of the W register are
loaded in the OPTION register. This
instruction is supported for code
compatibility with PIC16C5X products.
Since OPTION is a readable/writable
register, the user can directly
address it.
Words: 1
Cycles: 1
Example
To maintain upward compatibility
with future PICmicro™ products,
do not use this instruction.
RETFIE Return from Interrupt
Syntax: [
label
] RETFIE
Operands: None
Operation: TOS → PC,
1 → GIE
Status Affected: None
Encoding:
00 0000 0000 1001
Description:
Return from Interrupt. Stack is POP ed
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.
Words: 1
Cycles: 2
Example
RETFIE
After Interrupt
PC = TOS
GIE = 1
RETLW Return with Literal in W
Syntax: [
label
] RETLW k
Operands: 0 ≤ k ≤ 255
Operation: k → (W);
TOS → PC
Status Affected: None
Encoding:
11 01xx kkkk kkkk
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
TABLE
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
PIC16C55X(A)
DS40143B-page 60 Preliminary 1997 Microchip Technology Inc.
RETURN Return from Subroutine
Syntax: [
label
] RETURN
Operands: None
Operation: TOS → PC
Status Affected: None
Encoding:
00 0000 0000 1000
Description:
Return from subroutine. The stack is
POPed and the top of the stack (T OS)
is loaded into the program counter.
This is a two cycle instruction.
Words: 1
Cycles: 2
Example
RETURN
After Interrupt
PC = TOS
RLF Rotate Left f through Carry
Syntax: [
label
] RLF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: See description below
Status Affected: C
Encoding:
00 1101 dfff ffff
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'.
Words: 1
Cycles: 1
Example
RLF REG1,0
Before Instruction
REG1 = 1110 0110
C = 0
After Instruction
REG1 = 1110 0110
W = 1100 1100
C = 1
Register fC
RRF Rotate Right f through Carry
Syntax: [
label
] RRF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: See description below
Status Affected: C
Encoding:
00 1100 dfff ffff
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'.
Words: 1
Cycles: 1
Example
RRF REG1,0
Before Instruction
REG1 = 1110 0110
C = 0
After Instruction
REG1 = 1110 0110
W = 0111 0011
C = 0
SLEEP
Syntax: [
label
] SLEEP
Operands: None
Operation: 00h → WDT,
0 → WDT prescaler,
1 → T
O,
0 → PD
Status Affected: TO, PD
Encoding:
00 0000 0110 0011
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.
See Section 7.8 for more details.
Words: 1
Cycles: 1
Example: SLEEP
Register fC
1997 Microchip Technology Inc. Preliminary DS40143B-page 61
PIC16C55X(A)
SUBLW Subtract W from Literal
Syntax: [
label
] SUBLW k
Operands: 0 ≤ k ≤ 255
Operation: k - (W) → (W)
Status
Affected:
C, DC, Z
Encoding: 11 110x kkkk kkkk
Description:
The W register is subtracted (2’s complement method) from the eight bit literal
'k'. The result is placed in the W register.
Words: 1
Cycles: 1
Example 1: SUBLW 0x02
Before Instruction
W = 1
C = ?
After Instruction
W = 1
C = 1; result is positive
Example 2: Before Instruction
W = 2
C = ?
After Instruction
W = 0
C = 1; result is zero
Example 3: Before Instruction
W = 3
C = ?
After Instruction
W = 0xFF
C = 0; result is negative
SUBWF Subtract W from f
Syntax: [
label
] SUBWF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f) - (W) → (dest)
Status
Affected:
C, DC, Z
Encoding: 00 0010 dfff ffff
Description:
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'.
Words: 1
Cycles: 1
Example 1: SUBWF REG1,1
Before Instruction
REG1 = 3
W = 2
C = ?
After Instruction
REG1 = 1
W = 2
C = 1; result is positive
Example 2: Before Instruction
REG1 = 2
W = 2
C = ?
After Instruction
REG1 = 0
W = 2
C = 1; result is zero
Example 3: Before Instruction
REG1 = 1
W = 2
C = ?
After Instruction
REG1 = 0xFF
W = 2
C = 0; result is negative
PIC16C55X(A)
DS40143B-page 62 Preliminary 1997 Microchip Technology Inc.
SWAPF Swap Nibbles in f
Syntax: [
label
] SWAPF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f<3:0>) → (dest<7:4>),
(f<7:4>) → (dest<3:0>)
Status Affected: None
Encoding:
00
1110 dfff ffff
Description:
The upper and lower nibbles of
register 'f' are exchanged. If 'd' is 0
the result is placed in W register. If 'd'
is 1 the result is placed in register 'f'.
Words: 1
Cycles: 1
Example
SWAPF REG, 0
Before Instruction
REG1 = 0xA5
After Instruction
REG1 = 0xA5
W = 0x5A
TRIS Load TRIS Register
Syntax: [
label
] TRIS f
Operands: 5 ≤ f ≤ 7
Operation: (W) → TRIS register f;
Status Affected: None
Encoding:
00
0000 0110 0fff
Description:
The instruction is supported for code
compatibility with the PIC16C5X
products. Since TRIS registers are
readable and writable, the user can
directly address them.
Words: 1
Cycles: 1
Example
To maintain upward compatibility
with future PICmicro™ products,
do not use this instruction.
XORLW Exclusive OR Literal with W
Syntax: [
label
] XORLW k
Operands: 0 ≤ k ≤ 255
Operation: (W) .XOR. k → (W)
Status Affected: Z
Encoding: 11 1010 kkkk kkkk
Description:
The contents of the W register are
XOR’ed with the eight bit literal 'k'.
The result is placed in the
W register.
Words: 1
Cycles: 1
Example: XORLW 0xAF
Before Instruction
W = 0xB5
After Instruction
W = 0x1A
XORWF Exclusive OR W with f
Syntax: [
label
] XORWF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (W) .XOR. (f) → (dest)
Status Affected: Z
Encoding:
00 0110 dfff ffff
Description:
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'.
Words: 1
Cycles: 1
Example XORWF
REG 1
Before Instruction
REG = 0xAF
W = 0xB5
After Instruction
REG = 0x1A
W = 0xB5
1997 Microchip Technology Inc. DS40143B - page 63
PIC16C55X(A)
9.0 DEVELOPMENT SUPPORT
9.1 Development Tools
The PICmicrο microcontrollers are supported with a
full range of hardware and software dev elopment tools:
• PICMASTER/DS40143BICMASTER CE Real-Time
In-Circuit Emulator
• ICEPIC Low-Cost PIC16C5X and PIC16CXXX
In-Circuit Emulator
• PRO MATE
II Universal Programmer
• PICSTART
Plus Entry-Level Prototype
Programmer
• PICDEM-1 Low-Cost Demonstration Board
• PICDEM-2 Low-Cost Demonstration Board
• PICDEM-3 Low-Cost Demonstration Board
• MPASM Assembler
• MPLAB SIM Software Simulator
• MPLAB-C (C Compiler)
• Fuzzy Logic Development System
(
fuzzy
TECH−MP)
9.2 PICMASTER: High Performance
Universal In-Circuit Emulator with
MPLAB IDE
The PICMASTER Universal In-Circuit Emulator is
intended to provide the product development engineer
with a complete microcontroller design tool set for all
microcontrollers in the SX, PIC14C000, PIC16C5X,
PIC16CXXX and PIC17CXX families. PICMASTER is
supplied with the MPLAB Integrated Development
Environment (IDE), which allows editing, “make” and
download, and source debugging from a single environment.
Interchangeable target probes allow the system to be
easily reconfigured for emulation of different processors. The universal architecture of the PICMASTER
allows expansion to support all new Microchip microcontrollers.
The PICMASTER Emulator System has been
designed as a real-time emulation system with
advanced features that are generally found on more
expensive development tools. The PC compatible 386
(and higher) machine platform and Microsoft Windows
3.x environment were chosen to best make these fea-
tures available to you, the end user.
A CE compliant version of PICMASTER is availab le for
European Union (EU) countries.
9.3 ICEPIC: Low-Cost PICmicro™
In-Circuit Emulator
ICEPIC is a low-cost in-circuit emulator solution for the
Microchip PIC12CXXX, PIC16C5X and PIC16CXXX
families of 8-bit OTP microcontrollers.
ICEPIC is designed to operate on PC-compatible
machines ranging from 286-AT
through Pentium
based machines under Windows 3.x environment.
ICEPIC features real time, non-intrusive emulation.
9.4 PRO MATE II: Universal Programmer
The PRO MATE II Universal Programmer is a full-featured programmer capable of operating in stand-alone
mode as well as PC-hosted mode.
The PRO MATE II has programmable V
DD and VPP
supplies which allows it to verify programmed memory
at V
DD min and VDD max for maximum reliability. It has
an LCD display for displaying error messages, keys to
enter commands and a modular detachable socket
assembly to support various package types. In standalone mode the PRO MATE II can read, verify or program PIC12CXXX, PIC14C000, PIC16C5X,
PIC16CXXX and PIC17CXX devices. It can also set
configuration and code-protect bits in this mode.
9.5 PICSTART Plus Entry Level
Development System
The PICSTART programmer is an easy-to-use, lowcost prototype programmer. It connects to the PC via
one of the COM (RS-232) ports. MPLAB Integrated
Development Environment software makes using the
programmer simple and efficient. PICSTART Plus is
not recommended for production programming.
PICSTART Plus supports all PIC12CXXX, PIC14C000,
PIC16C5X, PIC16CXXX and PIC17CXX devices with
up to 40 pins. Larger pin count devices such as the
PIC16C923 and PIC16C924 may be supported with an
adapter socket.
PIC16C55X(A)
DS40143B - page 64 1997 Microchip Technology Inc.
9.6 PICDEM-1 Low-Cost PICmicro
Demonstration Board
The PICDEM-1 is a simple board which demonstrates
the capabilities of several of Microchip’s microcontrollers. The microcontrollers supported are: PIC16C5X
(PIC16C54 to PIC16C58A), PIC16C61, PIC16C62X,
PIC16C71, PIC16C8X, PIC17C42, PIC17C43 and
PIC17C44. All necessary hardware and software is
included to run basic demo programs. The users can
program the sample microcontrollers provided with
the PICDEM-1 board, on a PRO MATE II or
PICSTART-Plus programmer, and easily test firmware. The user can also connect the PICDEM-1
board to the PICMASTER emulator and download
the firmware to the emulator for testing. Additional prototype area is available for the user to build some additional hardware and connect it to the microcontroller
socket(s). Some of the features include an RS-232
interface, a potentiometer for simulated analog input,
push-button switches and eight LEDs connected to
PORTB.
9.7 PICDEM-2 Low-Cost PIC16CXX
Demonstration Board
The PICDEM-2 is a simple demonstration board that
supports the PIC16C62, PIC16C64, PIC16C65,
PIC16C73 and PIC16C74 microcontrollers. All the
necessary hardware and software is included to
run the basic demonstration programs. The user
can program the sample microcontrollers provided
with the PICDEM-2 board, on a PRO MATE II programmer or PICSTART-Plus, and easily test firmware.
The PICMASTER emulator may also be used with the
PICDEM-2 board to test firmware. Additional prototype
area has been provided to the user for adding additional hardware and connecting it to the microcontroller
socket(s). Some of the f eatures include a RS-232 interface, push-button switches, a potentiometer for simulated analog input, a Serial EEPROM to demonstrate
usage of the I
2
C bus and separate headers for connec-
tion to an LCD module and a keypad.
9.8 PICDEM-3 Low-Cost PIC16CXXX
Demonstration Board
The PICDEM-3 is a simple demonstration board that
supports the PIC16C923 and PIC16C924 in the PLCC
package. It will also support future 44-pin PLCC
microcontrollers with a LCD Module. All the necessary hardware and software is included to run the
basic demonstration programs. The user can program the sample microcontrollers provided with
the PICDEM-3 board, on a PRO MATE II programmer or PICSTART Plus with an adapter socket, and
easily test firmware. The PICMASTER emulator may
also be used with the PICDEM-3 board to test firmware. Additional prototype area has been provided to
the user for adding hardware and connecting it to the
microcontroller socket(s). Some of the f eatures include
an RS-232 interface, push-button switches, a potentiometer for simulated analog input, a thermistor and
separate headers for connection to an external LCD
module and a keypad. Also provided on the PICDEM-3
board is an LCD panel, with 4 commons and 12 segments, that is capable of displaying time, temperature
and day of the week. The PICDEM-3 provides an additional RS-232 interface and Windows 3.1 software for
showing the demultiplex ed LCD signals on a PC. A simple serial interface allows the user to construct a hardware demultiplexer for the LCD signals.
9.9 MPLAB™ Integrated Development
Environment Software
The MPLAB IDE Software brings an ease of software
development previously unseen in the 8-bit microcontroller market. MPLAB is a windows based application
which contains:
• A full featured editor
• Three operating modes
- editor
- emulator
- simulator
• A project manager
• Customizable tool bar and key mapping
• A status bar with project information
• Extensive on-line help
MPLAB allows you to:
• Edit your source files (either assembly or ‘C’)
• One touch assemble (or compile) and download
to PICmicro tools (automatically updates all
project information)
• Debug using:
- source files
- absolute listing file
• Transfer data dynamically via DDE (soon to be
replaced by OLE)
• Run up to four emulators on the same PC
The ability to use MPLAB with Microchip’s simulator
allows a consistent platform and the ability to easily
switch from the low cost simulator to the full featured
emulator with minimal retraining due to development
tools.
9.10 Assembler (MPASM)
The MPASM Universal Macro Assembler is a PChosted symbolic assembler. It suppor ts all microcontroller series including the PIC12C5XX, PIC14000,
PIC16C5X, PIC16CXXX, and PIC17CXX families.
MPASM offers full featured Macro capabilities, conditional assembly , and se ver al source and listing formats.
It generates various object code formats to support
Microchip's development tools as well as third party
programmers.
MPASM allows full symbolic debugging from
PICMASTER, Microchip’s Universal Emulator System.
1997 Microchip Technology Inc. DS40143B - page 65
PIC16C55X(A)
MPASM has the following features to assist in developing software for specific use applications.
• Provides translation of Assembler source code to
object code for all Microchip microcontrollers.
• Macro assembly capability.
• Produces all the files (Object, Listing, Symbol,
and special) required for symbolic debug with
Microchip’s emulator systems.
• Supports Hex (default), Decimal and Octal source
and listing formats.
MPASM provides a rich directive language to support
programming of the PICmicro. Directives are helpful in
making the development of your assemb le source code
shorter and more maintainable.
9.11 Software Simulator (MPLAB-SIM)
The MPLAB-SIM Software Simulator allows code
development in a PC host environment. It allows the
user to simulate the PICmicro series microcontrollers
on an instruction level. On any given instruction, the
user may examine or modify any of the data areas or
provide external stimulus to any of the pins. The input/
output radix can be set by the user and the execution
can be performed in; single step , ex ecute until break, or
in a trace mode.
MPLAB-SIM fully supports symbolic debugging using
MPLAB-C and MPASM. The Software Simulator offers
the low cost flexibility to develop and debug code outside of the laboratory environment making it an excellent multi-project software development tool.
9.12 C Compiler (MPLAB-C)
The MPLAB-C Code Development System is a
complete ‘C’ compiler and integrated development
environment for Microchip’s PICmicro™ family of
microcontrollers. The compiler provides powerful integration capabilities and ease of use not found with
other compilers.
For easier source level debugging, the compiler provides symbol information that is compatible with the
MPLAB IDE memory display.
9.13 Fuzzy Logic Development System
(
fuzzy
TECH-MP)
fuzzy
TECH-MP fuzzy logic development tool is available in two versions - a low cost introductory version,
MP Explorer, for designers to gain a comprehensive
working knowledge of fuzzy logic system design; and a
full-featured version,
fuzzy
TECH-MP, edition for imple-
menting more complex systems.
Both versions include Microchip’s
fuzzy
LAB demonstration board for hands-on experience with fuzzy logic
systems implementation.
9.14 MP-DriveWay – Application Code
Generator
MP-DriveWay is an easy-to-use Windows-based Application Code Generator. With MP-DriveWay you can
visually configure all the peripherals in a PICmicro
device and, with a click of the mouse, generate all the
initialization and many functional code modules in C
language. The output is fully compatible with Microchip’s MPLAB-C C compiler. The code produced is
highly modular and allows easy integration of your own
code. MP-DriveWay is intelligent enough to maintain
your code through subsequent code generation.
9.15 SEEVAL Evaluation and
Programming System
The SEEVAL SEEPROM Designer’s Kit supports all
Microchip 2-wire and 3-wire Serial EEPROMs. The kit
includes everything necessary to read, write, erase or
program special features of any Microchip SEEPROM
product including Smart Serials and secure serials.
The Total Endurance Disk is included to aid in tradeoff analysis and reliability calculations. The total kit can
significantly reduce time-to-market and result in an
optimized system.
9.16 KEELOQ Evaluation and
Programming Tools
KEELOQ evaluation and programming tools support
Microchips HCS Secure Data Products. The HCS evaluation kit includes an LCD display to show changing
codes, a decoder to decode transmissions, and a programming interface to program test transmitters.
PIC16C55X(A)
DS40143B - page 66 1997 Microchip Technology Inc.
TABLE 9-1: DEVELOPMENT TOOLS FROM MICROCHIP
PIC12C5XX PIC14000 PIC16C5X PIC16CXXX PIC16C6X PIC16C7XX PIC16C8X PIC16C9XX PIC17C4X PIC17C75X
24CXX
25CXX
93CXX
HCS200
HCS300
HCS301
Emulator Products
PICMASTER
/
PICMASTER-CE
In-Circuit Emulator
✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
Available
3Q97
ICEPIC Low-Cost
In-Circuit Emulator
✔ ✔ ✔ ✔ ✔ ✔
Software Tools
MPLAB
Integrated
Development
Environment
✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
MPLAB C
Compiler
✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
fuzzy
TECH
-MP
Explorer/Edition
Fuzzy Logic
Dev. Tool
✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
MP-DriveWay
Applications
Code Generator
✔ ✔ ✔ ✔ ✔ ✔
Total Endurance
Software Model
✔
Programmers
PICSTART
Lite Ultra Low-Cost
Dev. Kit
✔ ✔ ✔ ✔
PICSTART
Plus Low-Cost
Universal Dev. Kit
✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
PRO MATE
II
Universal
Programmer
✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
KEELOQ
Programmer
✔
Demo Boards
SEEVAL
Designers Kit
✔
PICDEM-1
✔ ✔ ✔ ✔
PICDEM-2
✔ ✔
PICDEM-3
✔
KEELOQ
Evaluation Kit
✔
1997 Microchip Technology Inc. Preliminary DS40143B-page 67
PIC16C55X(A)
10.0 ELECTRICAL SPECIFICATIONS
Absolute Maximum Ratings †
Ambient Temperature under bias ............................................................................................................. –40° to +125°C
Storage Temperature................................................................................................................................ –65° to +150°C
Voltage on any pin with respect to V
SS (except VDD and MCLR)...................................................... –0.6V to VDD +0.6V
Voltage on V
DD with respect to VSS ............................................................................................................... 0 to +7.5V
Voltage on MCLR
with respect to VSS (Note 2)................................................................................................. 0 to +14V
Total power Dissipation (Note 1)...............................................................................................................................1.0W
Maximum Current out of V
SS pin...........................................................................................................................300 mA
Maximum Current into V
DD pin..............................................................................................................................250 mA
Input Clamp Current, I
IK (VI<0 or VI> VDD) ...................................................................................................................... ±20 mA
Output Clamp Current, I
OK (V0 <0 or V0>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 PORTA and PORTB ...................................................................................................200 mA
Maximum Current sourced by PORTA and PORTB..............................................................................................200 mA
Note 1: Power dissipation is calculated as follows: P
DIS = 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 to maximum rating conditions
for extended periods may affect device reliability.
PIC16C55X(A)
DS40143B-page 68 Preliminary 1997 Microchip Technology Inc.
TABLE 10-1: CROSS REFERENCE OF DEVICE SPECS FOR OSCILLATOR CONFIGURATIONS
AND FREQUENCIES OF OPERATION (COMMERCIAL DEVICES)
OSC PIC16C55X-04 PIC16C55XA-04 PIC16C55X-20 PIC16C55XA-20 PIC16LC55X-04
PIC16C55X
JW Devices
PIC16C55XA
JW Devices
RC
V
DD: 3.0V to
5.5V
I
DD: 3.3 mA
max.@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
V
DD: 3.0V to
5.5V
I
DD: 3.3 mA
max.@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
VDD: 4.5V to 5.5V
I
DD: 1.8 mA typ.
@5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 4.0 MHz
max.
VDD: 4.5V to 5.5V
I
DD: 1.8 mA typ.
@5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 4.0 MHz
max.
V
DD: 2.5V to 5.5V
I
DD: 1.4 mA typ.
@3.0V
I
PD: 0.7 µA typ.
@3.0V
Freq: 4.0 MHz
max.
V
DD: 3.0V to 5.5V
I
DD: 3.3 mA max.
@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
V
DD: 3.0V to 5.5V
I
DD: 3.3 mA max.
@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
XT
V
DD: 3.0V to
5.5V
I
DD: 3.3 mA
max.@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
V
DD: 3.0V to
5.5V
I
DD: 3.3 mA
max.@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
VDD: 4.5V to 5.5V
I
DD: 1.8 mA typ.
@5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 4.0 MHz
max.
VDD: 4.5V to 5.5V
I
DD: 1.8 mA typ.
@5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 4.0 MHz
max.
V
DD: 2.5V to 5.5V
I
DD: 1.4 mA typ.
@3.0V
I
PD: 0.7 µA typ.
@3.0V
Freq: 4.0 MHz
max.
V
DD: 3.0V to 5.5V
I
DD: 3.3 mA max.
@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
V
DD: 3.0V to 5.5V
I
DD: 3.3 mA max.
@5.5V
I
PD: 20 µA max.
@4.0V
Freq: 4.0 MHz
max.
HS
VDD: 4.5V to
5.5V
I
DD: 9.0 mA typ.
@5.5V
I
PD: 1.0 µA typ.
@4.0V
Freq: 4.0 MHz
max.
VDD: 4.5V to
5.5V
I
DD: 9.0 mA typ.
@5.5V
I
PD: 1.0 µA typ.
@4.0V
Freq: 4.0 MHz
max.
V
DD: 4.5V to
5.5V
I
DD: 20 mA
max. @5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 20 MHz
max.
V
DD: 4.5V to
5.5V
I
DD: 20 mA
max. @5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 20 MHz
max.
Do not use in
HS mode
VDD: 4.5V to
5.5V
I
DD: 20 mA
max.@5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 20 MHz
max.
V
DD: 4.5V to
5.5V
I
DD: 20 mA
max.@5.5V
I
PD: 1.0 µA typ.
@4.5V
Freq: 20 MHz
max.
LP
VDD: 3.0V to
5.5V
I
DD: 35 µA typ.
@32 kHz,
3.0V
I
PD: 1.0 µA typ.
@4.0 V
Freq: 200 kHz
maxi.
VDD: 3.0V to
5.5V
I
DD: 35 µA typ.
@32 kHz,
3.0V
I
PD: 1.0 µA typ.
@4.0 V
Freq: 200 kHz
maxi.
Do not use in LP
mode
Do not use in LP
mode
V
DD: 2.5V to
5.5V
I
DD: 32 µA max.
@32 kHz,
3.0V
I
PD: 9.0 µA
max. @3.0V
Freq: 200 kHz
max.
V
DD: 2.5V to
5.5V
I
DD: 32 µA max.
@32 kHz,
3.0V
I
PD: 9.0 µA
max. @3.0V
Freq: 200 kHz
max.
V
DD: 3.0V to
5.5V
I
DD: 32 µA max.
@32 kHz,
3.0V
I
PD: 9.0 µA
max.@3.0V
Freq: 200 kHz
max.
The shaded sections indicate oscillator selections which are tested for functionality, but not for MIN/MAX specifications. It is recommended that the user select the device type that guarantees the specifications required.
1997 Microchip Technology Inc. Preliminary DS40143B-page 69
PIC16C55X(A)
(A)
10.1 DC CHARACTERISTICS: PIC16C55X(A)-04 (Commercial, Industrial, Extended)
PIC16C55X(A)-20 (Commercial, Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature –40°C ≤ T
A ≤ +85°C for industrial and
0°C ≤ T
A ≤ +70°C for commercial and
–40°C ≤ T
A ≤ +125°C for extended
Param
No.
Sym Characteristic Min Typ† Max Units Conditions
D001
D001A
V
DD Supply Voltage 3.0
4.5
--5.5
5.5VV
XT, RC and LP osc configuration
HS osc configuration
D002 V
DR RAM Data Retention
Voltage (Note 1)
– 1.5* – V Device in SLEEP mode
D003 V
POR VDD start voltage to
ensure Power-on Reset
– VSS – V See section on power-on reset for
details
D004 S
VDD VDD rise rate to ensure
Power-on Reset
0.05* – – V/ms See section on power-on reset for
details
D010
D010A
D013
I
DD Supply Current (Note 2) –
–
–
1.8
35
9.0
3.3
70
20
mA
µA
mA
XT and RC osc configuration
F
OSC = 4 MHz, VDD = 5.5V, WDT
disabled (Note 4)
LP osc configuration,
PIC16C55X-04 only
F
OSC = 32 kHz, VDD = 4.0V, WDT
disabled
HS osc configuration
F
OSC = 20 MHz, VDD = 5.5V, WDT
disabled
∆I
WDT WDT Current (Note 5) – 6.0 20
25µAµA
VDD = 4.0V
(+85°C to +125°C)
D020 I
PD Power Down Current (Note 3) – 1.0 2.5
15µAµA
VDD=4.0V, WDT disabled
(+85°C to +125°C)
∆I
WDT WDT Current (Note 5) – 6.0 20 µA VDD=4.0V
(+85°C to +125°C)
* 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: This is the limit to which V
DD can be lowered in SLEEP mode without losing RAM data.
2: 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.
The test conditions for all I
DD measurements in active operation mode are:
OSC1 = external square wave, from rail to rail; all I/O pins configured as input, pulled to V
DD,
MCLR
= VDD; WDT enabled/disabled as specified.
3: 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 configured as input and tied to V
DD or VSS.
4: For RC osc configuration, current through Rext is not included. The current through the resistor can be
estimated by the formula Ir = V
DD/2Rext (mA) with Rext in kΩ.
5: The ∆ current is the additional current consumed when this peripheral is enabled. This current should be
added to the base I
DD or IPD measurement.
PIC16C55X(A)
DS40143B-page 70 Preliminary 1997 Microchip Technology Inc.
10.2 DC CHARACTERISTICS: PIC16LC55X-04 (Commercial, Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature –40˚C ≤ TA ≤ +85˚C for industrial and
0˚C ≤ TA ≤ +70˚C for commercial and
–40˚C ≤ TA ≤ +125˚C for extended
Param
No.
Sym Characteristic Min Typ† Max Units Conditions
D001 V
DD Supply Voltage 3.0
2.5
- 5.5
5.5
V XT and RC osc configuration
LP osc configuration
D002 V
DR RAM Data Retention
Voltage (Note 1)
– 1.5* – V Device in SLEEP mode
D003 V
POR VDD start voltage to
ensure Power-on Reset
– VSS – V See section on Power-on Reset for
details
D004 S
VDD VDD rise rate to ensure
Power-on Reset
0.05* – – V/ms See section on Power-on Reset for
details
D010
D010A
I
DD Supply Current (Note 2) –
–
1.4262.553mAµAXT and RC osc configuration
F
OSC = 2.0 MHz, VDD = 3.0V, WDT
disabled (Note 4)
LP osc configuration
F
OSC = 32 kHz, VDD = 3.0V, WDT
disabled
∆I
WDT WDT Current (Note 5) – 6.0 15 µA VDD = 3.0V
D020 I
PD Power Down Current (Note 3) – 0.7 2 µA VDD=3.0V, WDT disabled
∆I
WDT WDT Current (Note 5) – 6.0 15 µA VDD=3.0V
* 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: This is the limit to which V
DD can be lowered in SLEEP mode without losing RAM data.
2: 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.
The test conditions for all IDD measurements in active operation mode are:
OSC1=external square wave, from rail to rail; all I/O pins configured as input, pulled to V
DD,
MCLR
= VDD; WDT enabled/disabled as specified.
3: 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 configured as input and tied to V
DD or VSS.
4: For RC osc configuration, current through Rext is not included. The current through the resistor can be
estimated by the formula Ir = V
DD/2Rext (mA) with Rext in kΩ.
5: The ∆ current is the additional current consumed when this peripheral is enabled. This current should be
added to the base I
DD or IPD measurement.
1997 Microchip Technology Inc. Preliminary DS40143B-page 71
PIC16C55X(A)
10.3 DC CHARACTERISTICS: PIC16C55X(A) (Commercial, Industrial, Extended)
PIC16LC55X (Commercial, Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature –40˚C ≤ TA ≤ +85˚C for industrial and
0˚C ≤ TA ≤ +70˚C for commercial and
–40˚C ≤ TA ≤ +125˚C for automotive
Operating voltage V
DD range as described in DC spec Table 10-1
Param.
No.
Sym
Characteristic Min Typ† Max Unit Conditions
VIL
Input Low Voltage
I/O ports
D030 with TTL buffer V
SS - 0.8V
0.15V
DD
V VDD = 4.5V to 5.5V
otherwise
D031 with Schmitt Trigger input V
SS 0.2VDD V
D032 MCLR
, RA4/T0CKI,OSC1 (in
RC mode)
Vss - 0.2VDD V Note1
D033 OSC1 (in XT* and HS) Vss - 0.3V
DD V
OSC1 (in LP*) Vss - 0.6V
DD-1.0 V
VIH
Input High Voltage
I/O ports -
D040 with TTL buffer 2.0V - V
DD V
D041 with Schmitt Trigger input 0.8V
DD VDD
D042 MCLR RA4/T0CKI 0.8VDD - VDD V
D043
D043A
OSC1 (XT*, HS and LP*)
OSC1 (in RC mode)
0.7V
DD
0.9VDD
- VDD V
Note1
D070
IPURB
PORTB weak pull-up current 50 200 400 µA VDD = 5.0V, VPIN = VSS
IIL
Input Leakage Current
(Notes 2, 3)
I/O ports (Except PORTA) ±1.0 µA V
SS ≤ VPIN ≤ VDD, pin at hi-impedance
D060 PORTA - - ±0.5 µA Vss ≤ V
PIN ≤ VDD, pin at hi-impedance
D061 RA4/T0CKI - - ±1.0 µA Vss ≤ V
PIN ≤ VDD
D063 OSC1, MCLR - - ±5.0 µA Vss ≤ VPIN ≤ VDD, XT, HS and LP osc
configuration
VOL
Output Low Voltage
D080 I/O ports - - 0.6 V I
OL=8.5 mA, VDD=4.5V, -40° to +85°C
- - 0.6 V I
OL=7.0 mA, VDD=4.5V, +125°C
D083 OSC2/CLKOUT - - 0.6 V I
OL=1.6 mA, VDD=4.5V, -40° to +85°C
(RC only) - - 0.6 V I
OL=1.2 mA, VDD=4.5V, +125°C
VOH
Output High Voltage (Note 3)
D090 I/O ports (Except RA4) V
DD-0.7 - - V IOH=-3.0 mA, VDD=4.5V, -40° to +85°C
V
DD-0.7 - - V IOH=-2.5 mA,
V
DD=4.5V, +125°C
D092 OSC2/CLKOUT V
DD-0.7 - - V IOH=-1.3 mA, VDD=4.5V, -40° to +85°C
(RC only)
V
DD-0.7 - - V IOH=-1.0 mA,
V
DD=4.5V, +125°C
*
VOD
Open-Drain High Voltage 14* V RA4 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.
Note 1: In RC oscillator configuration, the OSC1 pin is a Schmitt Trigger input. It is not recommended that the
PIC16C55X(A) be driven with external clock in RC mode.
2: The leakage current on the MCLR
pin is strongly dependent on applied voltage level. The specified levels
represent normal operating conditions. Higher leakage current may be measured at different input voltages.
3: Negative current is defined as coming out of the pin.
PIC16C55X(A)
DS40143B-page 72 Preliminary 1997 Microchip Technology Inc.
Capacitive Loading Specs
on Output Pins
D100
COSC2
OSC2 pin 15 pF In XT , HS and LP modes when e xternal
clock used to drive OSC1.
D101
Cio
All I/O pins/OSC2 (in RC
mode)
50 pF
10.3 DC CHARACTERISTICS: PIC16C55X(A) (Commercial, Industrial, Extended)
PIC16LC55X (Commercial, Industrial, Extended) (Cont.)
Standard Operating Conditions (unless otherwise stated)
Operating temperature –40˚C ≤ TA ≤ +85˚C for industrial and
0˚C ≤ TA ≤ +70˚C for commercial and
–40˚C ≤ TA ≤ +125˚C for automotive
Operating voltage V
DD range as described in DC spec Table 10-1
Param.
No.
Sym
Characteristic Min Typ† Max Unit 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: In RC oscillator configuration, the OSC1 pin is a Schmitt Trigger input. It is not recommended that the
PIC16C55X(A) be driven with external clock in RC mode.
2: The leakage current on the MCLR
pin is strongly dependent on applied voltage level. The specified levels
represent normal operating conditions. Higher leakage current may be measured at different input voltages.
3: Negative current is defined as coming out of the pin.
1997 Microchip Technology Inc. Preliminary DS40143B-page 73
PIC16C55X(A)
10.4 Timing Parameter Symbology
The timing parameter symbols have been created with one of the following formats:
FIGURE 10-1: LOAD CONDITIONS
1. TppS2ppS
2. TppS
T
F Frequency T Time
Lowercase subscripts (pp) and their meanings:
pp
ck CLKOUT os OSC1
io I/O port t0 T0CKI
mc MCLR
Uppercase letters and their meanings:
S
F Fall P Period
H High R Rise
I Invalid (Hi-impedance) V Valid
L Low Z Hi-Impedance
VDD/2
C
L
RL
Pin Pin
V
SS
VSS
CL
RL = 464Ω
C
L = 50 pF for all pins except OSC2
15 pF for OSC2 output
Load condition 1
Load condition 2
PIC16C55X(A)
DS40143B-page 74 Preliminary 1997 Microchip Technology Inc.
10.5 Timing Diagrams and Specifications
FIGURE 10-2: EXTERNAL CLOCK TIMING
TABLE 10-2: EXTERNAL CLOCK TIMING REQUIREMENTS
Parameter
No.
Sym Characteristic Min Typ† Max Units Conditions
Fos External CLKIN Frequency
(Note 1)
DC — 4 MHz XT and RC osc mode, VDD=5.0V
DC — 20 MHz HS osc mode
DC — 200 kHz LP osc mode
Oscillator Frequency
(Note 1)
DC — 4 MHz RC osc mode, VDD=5.0V
0.1 — 4 MHz XT osc mode
1 — 20 MHz HS osc mode
DC – 200 kHz LP osc mode
1 Tosc External CLKIN Period
(Note 1)
250 — — ns XT and RC osc mode
50 — — ns HS osc mode
5 — — µs LP osc mode
Oscillator Period
(Note 1)
250 — — ns RC osc mode
250 — 10,000 ns XT osc mode
50 — 1,000 ns HS osc mode
5 — — µs LP osc mode
2 TCY Instruction Cycle Time (Note 1) 1.0 Fos/4 DC µs
TCY=FOS/4
3* TosL,
TosH
External Clock in (OSC1) High or
Low Time
100* — — ns XT osc mode
2* — — µs LP osc mode
20* — — ns HS osc mode
4* TosR,
TosF
External Clock in (OSC1) Rise or
Fall Time
25* — — ns XT osc mode
50* — — ns LP osc mode
15* — — ns HS osc mode
* 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: Instruction cycle period (T
CY) 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 the OSC1 pin.
When an external clock input is used, the "Max." cycle time limit is "DC" (no clock) for all devices.
OSC1
CLKOUT
Q4
Q1 Q2
Q3 Q4 Q1
1 3 3
4 4
2
1997 Microchip Technology Inc. Preliminary DS40143B-page 75
PIC16C55X(A)
FIGURE 10-3: CLKOUT AND I/O TIMING
TABLE 10-3: CLKOUT AND I/O TIMING REQUIREMENTS
Parameter # Sym Characteristic Min Typ† Max Units
10* TosH2ckL OSC1↑ to CLKOUT↓ (Note1) —
—
75
—
200
400
ns
ns
11* TosH2ckH
OSC1↑ to CLKOUT↑ (Note1)
—
—
75
—
200
400
ns
ns
12* TckR
CLKOUT rise time (Note1)
—
—
35
—
100
200
ns
ns
13* TckF
CLKOUT fall time (Note1)
—
—
35
—
100
200
ns
ns
14* TckL2ioV
CLKOUT ↓ to Port out valid (Note1)
— — 20 ns
15* TioV2ckH
Port in valid before CLKOUT ↑ (Note1)
Tosc +200 ns
Tosc +400 ns——
—
—
ns
ns
16* TckH2ioI
Port in hold after CLKOUT ↑ (Note1)
0 — — ns
17* TosH2ioV OSC1↑ (Q1 cycle) to Port out valid —
—
50 150
300
ns
ns
18* TosH2ioI OSC1↑ (Q2 cycle) to Port input invalid (I/O in hold
time)
100
200
—
—
—
—
ns
ns
19* TioV2osH Port input valid to OSC1↑ (I/O in setup time) 0 — — ns
20* TioR Port output rise time —
—
10
—
40
80
ns
ns
21* TioF Port output fall time —
—
10
—
40
80
ns
ns
22* Tinp RB0/INT pin high or low time 25
40
—
—
—
—
ns
ns
23 Trbp RB<7:4> change interrupt high or low time Tcy — — ns
* 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: Measurements are taken in RC Mode where CLKOUT output is 4 x TOSC
22
23
Note: All tests must be do with specified capacitance loads (Figure 10-1) 50 pF on I/O pins and CLKOUT
OSC1
CLKOUT
I/O Pin
(input)
I/O Pin
(output)
Q4
Q1
Q2 Q3
10
13
14
17
20, 21
19
18
15
11
12
16
old value
new value
PIC16C55X(A)
DS40143B-page 76 Preliminary 1997 Microchip Technology Inc.
FIGURE 10-4: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP
TIMER TIMING
TABLE 10-4: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP
TIMER REQUIREMENTS
Parameter
No.
Sym Characteristic Min Typ† Max Units Conditions
30 TmcL MCLR Pulse Width (low) 2000 — — ns
-40
° to +85°C
31 Twdt Watchdog Timer Time-out Period
(No Prescaler)
7* 18 33* ms
VDD = 5.0V, -40° to +85°C
32 Tost Oscillation Start-up Timer Period — 1024 T
OSC — — TOSC = OSC1 period
33 Tpwrt Power-up Timer Period 28* 72 132* ms
VDD = 5.0V, -40° to +85°C
34 T
IOZ I/O hi-impedance from MCLR low — 2.0 µs
* 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.
VDD
MCLR
Internal
POR
PWRT
Timeout
OSC
Timeout
Internal
RESET
Watchdog
Timer
RESET
33
32
30
31
34
I/O Pins
34
1997 Microchip Technology Inc. Preliminary DS40143B-page 77
PIC16C55X(A)
FIGURE 10-5: TIMER0 CLOCK TIMING
TABLE 10-5: TIMER0 CLOCK REQUIREMENTS
FIGURE 10-6: LOAD CONDITIONS
Parameter
No.
Sym Characteristic Min Typ† Max Units Conditions
40 Tt0H T0CKI High Pulse Width No Prescaler 0.5 T
CY + 20* — — ns
With Prescaler 10* — — ns
41 Tt0L T0CKI Low Pulse Width No Prescaler 0.5 TCY + 20* — — ns
With Prescaler 10* — — ns
42 Tt0P T0CKI Period TCY + 40*
N
— — ns N = prescale value
(1, 2, 4, ..., 256)
* 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.
41
42
40
RA4/T0CKI
TMR0
VDD/2
C
L
RL
Pin Pin
V
SS
VSS
CL
RL = 464Ω
C
L = 50 pF for all pins except OSC2
15 pF for OSC2 output
Load condition 1
Load condition 2
PIC16C55X(A)
DS40143B-page 78 Preliminary 1997 Microchip Technology Inc.
NOTES:
1997 Microchip Technology Inc. Preliminary DS40143B-page 79
PIC16C55X(A)
11.0 PACKAGING INFORMATION
Ceramic CERDIP Dual In-Line Family
Notes:
1. Controlling parameter: inches.
2. Parameter “e1” (“e”) is non-cumulative.
3. Seating plane (standoff) is defined by board hole size.
4. Parameter “B1” is nominal.
Symbol List for Ceramic CERDIP Dual In-Line Package Parameters
Symbol Description of Parameters
α Angular spacing between min. and max. lead positions measured at the gauge plane
A Distance between seating plane to highest point of body (lid)
A1 Distance between seating plane and base plane
A2 Distance from base plane to highest point of body (lid)
A3 Base body thickness
B Width of terminal leads
B1 Width of terminal lead shoulder which locate seating plane (standoff geometry optional)
C Thickness of terminal leads
D Largest overall package parameter of length
D1 Body width parameters not including leads
E Largest overall package width parameter outside of lead
E1 Body width parameter - end lead center to end lead center
eA Linear spacing of true minimum lead position center line to center line
eB Linear spacing between true lead position outside of lead to outside of lead
e1 Linear spacing between center lines of body standoffs (terminal leads)
L Distance from seating plane to end of lead
N Total number of potentially usable lead positions
S Distance from true position center line of Number 1 lead to the extremity of the body
S1 Distance from other end lead edge positions to the extremity of the body
PIC16C55X(A)
DS40143B-page 80 Preliminary 1997 Microchip Technology Inc.
11.1 18-Lead Ceramic CERDIP Dual In-line with Window (300 mil)
Package Group: Ceramic CERDIP Dual In-Line (CDP)
Symbol
Millimeters Inches
Min Max Notes Min Max Notes
α 0° 10° 0° 10°
A — 5.080 — 0.200
A1 0.381 1.7780 0.015 0.070
A2 3.810 4.699 0.150 0.185
A3 3.810 4.445 0.150 0.175
B 0.355 0.585 0.014 0.023
B1 1.270 1.651 Typical 0.050 0.065 Typical
C 0.203 0.381 Typical 0.008 0.015 Typical
D 22.352 23.622 0.880 0.930
D1 20.320 20.320 Reference 0.800 0.800 Reference
E 7.620 8.382 0.300 0.330
E1 5.588 7.874 0.220 0.310
e1 2.540 2.540 Reference 0.100 0.100 Reference
eA 7.366 8.128 Typical 0.290 0.320 Typical
eB 7.620 10.160 0.300 0.400
L 3.175 3.810 0.125 0.150
N 18 18 18 18
S 0.508 1.397 0.020 0.055
S1 0.381 1.270 0.015 0.050
N
Pin No. 1
Indicator
Area
E1
E
S
D
B1
B
D1
Base
Plane
Seating
Plane
S1
A1
A3
A
L
α
C
e
A
eB
e1
A2
1997 Microchip Technology Inc. Preliminary DS40143B-page 81
PIC16C55X(A)
Plastic Dual In-Line Family
Notes:
1. Controlling parameter: inches.
2. Parameter “e1” (“e”) is non-cumulative.
3. Seating plane (standoff) is defined by board hole size.
4. Parameter “B1” is nominal.
5. Details of pin Number 1 identifier are optional.
6. Parameters “D + E1” do not include mold flash/protrusions.
Mold flash or protrusions shall not exceed .010 inches.
Symbol List for Plastic In-Line Package Parameters
Symbol Description of Parameters
α Angular spacing between min. and max. lead positions measured at the gauge plane
A Distance between seating plane to highest point of body
A1 Distance between seating plane and base plane
A2 Base body thickness
B Width of terminal leads
B1 Width of terminal lead shoulder which locate seating plane (standoff geometry optional)
C Thickness of terminal leads
D Largest overall package parameter of length
D1 Body length parameter - end lead center to end lead center
E Largest overall package width parameter outside of lead
E1 Body width parameters not including leads
eA Linear spacing of true minimum lead position center line to center line
eB Linear spacing between true lead position outside of lead to outside of lead
e1 Linear spacing between center lines of body standoffs (terminal leads)
L Distance from seating plane to end of lead
N Total number of potentially usable lead positions
S Distance from true position center line of Number 1 lead to the extremity of the body
S1 Distance from other end lead edge positions to the extremity of the body
PIC16C55X(A)
DS40143B-page 82 Preliminary 1997 Microchip Technology Inc.
11.2 18-Lead Plastic Dual In-line (300 mil)
Package Group: Plastic Dual In-Line (PLA)
Symbol
Millimeters Inches
Min Max Notes Min Max Notes
A – 4.064 – 0.160
A1 0.381 – 0.015 –
A2 3.048 3.810 0.120 0.150
B 0.355 0.559 0.014 0.022
B1 1.524 1.524 Reference 0.060 0.060 Reference
C 0.203 0.381 Typical 0.008 0.015 Typical
D 22.479 23.495 0.885 0.925
D1 20.320 20.320 Reference 0.800 0.800 Reference
E 7.620 8.255 0.300 0.325
E1 6.096 7.112 0.240 0.280
e1 2.489 2.591 Typical 0.098 0.102 Typical
eA 7.620 7.620 Reference 0.300 0.300 Reference
eB 8.128 9.906 0.320 0.390
L 3.048 3.556 0.120 0.140
N 18 18 18 18
S 0.889 – 0.035 –
S1 0.127 – 0.005 –
N
Pin No. 1
Indicator
Area
E1
E
S
D
B1
B
D1
Base
Plane
Seating
Plane
S1
A1
A2
A
L
e1
C
eA
eB
1997 Microchip Technology Inc. Preliminary DS40143B-page 83
PIC16C55X(A)
Plastic Small Outline Family
Notes:
1. Controlling parameter: inches.
2. All packages are gull wing lead form.
3. "D" and "E" are reference datums and do not include mold flash or protrusions. Mold flash or protrusions shall
not exceed .006 package ends and .010 on sides.
4. The chamfer on the body is optional. If it is not present, a visual index feature must be located within the
cross-hatched area to indicate pin 1 position.
5. Terminal numbers are shown for reference.
Symbol List for Small Outline Package Parameters
Symbol Description of Parameters
α Angular spacing between min. and max. lead positions measured at the gauge plane
A Distance between seating plane to highest point of body
A1 Distance between seating plane and base plane
B Width of terminals
C Thickness of terminals
D Largest overall package parameter of length
E Largest overall package width parameter not including leads
e Linear spacing of true minimum lead position center line to center line
H Largest overall package dimension of width
L Length of terminal for soldering to a substrate
N Total number of potentially usable lead positions
CP Seating plane coplanarity
PIC16C55X(A)
DS40143B-page 84 Preliminary 1997 Microchip Technology Inc.
11.3 18-Lead Plastic Surface Mount (SOIC - Wide, 300 mil Body)
Package Group: Plastic SOIC (SO)
Symbol
Millimeters Inches
Min Max Notes Min Max Notes
α 0° 8° 0° 8°
A 2.362 2.642 0.093 0.104
A1 0.101 0.300 0.004 0.012
B 0.355 0.483 0.014 0.019
C 0.241 0.318 0.009 0.013
D 11.353 11.735 0.447 0.462
E 7.416 7.595 0.292 0.299
e 1.270 1.270 Reference 0.050 0.050 Reference
H 10.007 10.643 0.394 0.419
h 0.381 0.762 0.015 0.030
L 0.406 1.143 0.016 0.045
N 18 18 18 18
CP – 0.102 – 0.004
B
e
N
Index
Area
Chamfer
h x 45°
α
E
H
1
2
3
CP
h x 45°
C
L
Seating
Plane
Base
Plane
D
A1
A
1997 Microchip Technology Inc. Preliminary DS40143B-page 85
PIC16C55X(A)
11.4 20-Lead Plastic Surface Mount (SSOP - 209 mil Body 5.30 mm)
Package Group: Plastic SSOP
Symbol
Millimeters Inches
Min Max Notes Min Max Notes
α 0° 8° 0° 8°
A 1.730 1.990 0.068 0.078
A1 0.050 0.210 0.002 0.008
B 0.250 0.380 0.010 0.015
C 0.130 0.220 0.005 0.009
D 7.070 7.330 0.278 0.289
E 5.200 5.380 0.205 0.212
e 0.650 0.650 Reference 0.026 0.026 Reference
H 7.650 7.900 0.301 0.311
L 0.550 0.950 0.022 0.037
N 20 20 20 20
CP - 0.102 - 0.004
Index
area
N
H
1 2 3
E
e
B
CP
D
A
A1
Base plane
Seating plane
L
C
α
PIC16C55X(A)
DS40143B-page 86 Preliminary 1997 Microchip Technology Inc.
11.5 Package Marking Information
Legend: MM...M Microchip part number information
XX...X Customer specific information*
AA Year code (last 2 digits of calendar year)
BB Week code (week of January 1 is week ‘01’)
C Facility code of the plant at which wafer is manufactured
C = Chandler, Arizona, U.S.A.
D Mask revision number
E Assembly code of the plant or country of origin in which
part was assembled
Note: 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 OTP marking consists of Microchip part number, year code, week
code, facility code, mask rev#, and assembly code. For OTP marking beyond
this, certain price adders apply. Please chec k with your Microchip Sales Office.
For QTP devices, any special marking adders are included in QTP price.
20-Lead SSOP
XXXXXXXXXX
AABBCDE
XXXXXXXXXX
XXXXXXXX
XXXXXXXX
AABBCDE
18-Lead CERDIP Windowed
18-Lead SOIC (.300")
XXXXXXXXXXXX
AABBCDE
XXXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
AABBCDE
18-Lead PDIP
Example
-04I / 218
9551 CBP
PIC16C558A
16C558
/JW
9501 CBA
Example
Example
-04I / S0218
9518 CDK
PIC16C558
PIC16C558A
-04I / P456
9523 CBA
Example
1997 Microchip Technology Inc. Preliminary DS40143B-page 87
PIC16C55X(A)
APPENDIX A: ENHANCEMENTS
The following are the list of enhancements over the
PIC16C5X microcontroller family:
1. Instruction word length is increased to 14 bits.
This allows larger page sizes both in program
memory (4K now as opposed to 512 before) and
register file (up to 128 bytes now versus 32
bytes before).
2. A PC high latch register (PCLATH) is added to
handle program memory paging. PA2, PA1, PA0
bits are removed from STATUS register.
3. Data memory paging is slightly redefined.
STATUS register is modified.
4. Four new instructions have been added:
RETURN, RETFIE, ADDLW, and SUBLW.
Two instructions
TRIS and OPTION are being
phased out although they are kept for
compatibility with PIC16C5X.
5. OPTION and TRIS registers are made
addressable.
6. Interrupt capability is added. Interrupt vector is
at 0004h.
7. Stack size is increased to 8 deep.
8. Reset vector is changed to 0000h.
9. Reset of all registers is revised. Three different
reset (and wake-up) types are recognized.
Registers are reset differently.
10. Wake up from SLEEP through interrupt is
added.
11. Two separate timers, Oscillator Start-up Timer
(OST) and Power-up Timer (PWRT) are
included for more reliable power-up. These
timers are invoked selectively to avoid
unnecessary delays on power-up and wake-up.
12. PORTB has weak pull-ups and interrupt on
change feature.
13. Timer0 clock input, T0CKI pin is also a port pin
(RA4/T0CKI) and has a TRIS bit.
14. FSR is made a full 8-bit register.
15. “In-circuit programming” is made possible. The
user can program PIC16C55X devices using
only five pins: V
DD, VSS, VPP, RB6 (clock) and
RB7 (data in/out).
16. PCON status register is added with a
Power-on-Reset (POR
) status bit.
17. Code protection scheme is enhanced such that
portions of the program memory can be
protected, while the remainder is unprotected.
18. PORTA inputs are now Schmitt Trigger inputs.
APPENDIX B: COMPATIBILITY
To convert code written for PIC16C5X to
PIC16C55X(A), the user should take the following
steps:
1. Remove any program memory page select
operations (PA2, PA1, PA0 bits) for
CALL, GOTO.
2. Revisit any computed jump operations (write to
PC or add to PC, etc.) to make sure page bits
are set properly under the new scheme.
3. Eliminate any data memory page switching.
Redefine data variables to reallocate them.
4. Verify all writes to STATUS, OPTION, and FSR
registers since these have changed.
5. Change reset vector to 0000h.
PIC16C55X(A)
DS40143B-page 88 Preliminary 1997 Microchip Technology Inc.
NOTES:
1997 Microchip Technology Inc. Preliminary DS40143B-page 89
PIC16C55X(A)
INDEX
A
ADDLW Instruction .............................................................53
ADDWF Instruction............................................................. 53
ANDLW Instruction .............................................................53
ANDWF Instruction............................................................. 53
Architectural Overview..........................................................9
Assembler
MPASM Assembler..................................................... 64
B
BCF Instruction................................................................... 54
Block Diagram
TIMER0....................................................................... 29
TMR0/WDT PRESCALER.......................................... 32
BSF Instruction ...................................................................54
BTFSC Instruction............................................................... 54
BTFSS Instruction...............................................................55
C
CALL Instruction .................................................................55
Clocking Scheme/Instruction Cycle ....................................12
CLRF Instruction.................................................................55
CLRW Instruction................................................................55
CLRWDT Instruction...........................................................56
Code Protection.................................................................. 50
COMF Instruction................................................................56
Configuration Bits................................................................ 36
D
Data Memory Organization.................................................14
DECF Instruction................................................................. 56
DECFSZ Instruction............................................................56
Development Support......................................................... 63
Development Tools.............................................................63
E
External Crystal Oscillator Circuit .......................................38
F
Fuzzy Logic Dev. System (
fuzzy
TECH-MP) ....................65
G
General purpose Register File............................................14
GOTO Instruction................................................................57
I
I/O Ports..............................................................................23
I/O Programming Considerations........................................ 27
ICEPIC Low-Cost PIC16CXXX In-Circuit Emulator............ 63
ID Locations........................................................................50
INCF Instruction..................................................................57
INCFSZ Instruction .............................................................57
In-Circuit Serial Programming.............................................50
Indirect Addressing, INDF and FSR Registers ...................22
Instruction Flow/Pipelining.................................................. 12
Instruction Set
ADDLW.......................................................................53
ADDWF....................................................................... 53
ANDLW.......................................................................53
ANDWF....................................................................... 53
BCF............................................................................. 54
BSF.............................................................................54
BTFSC........................................................................ 54
BTFSS ........................................................................55
CALL...........................................................................55
CLRF...........................................................................55
CLRW .........................................................................55
CLRWDT.....................................................................56
COMF......................................................................... 56
DECF.......................................................................... 56
DECFSZ..................................................................... 56
GOTO......................................................................... 57
INCF........................................................................... 57
INCFSZ....................................................................... 57
IORLW........................................................................ 57
IORWF........................................................................ 58
MOVF......................................................................... 58
MOVLW...................................................................... 58
MOVWF...................................................................... 58
NOP............................................................................ 59
OPTION...................................................................... 59
RETFIE....................................................................... 59
RETLW....................................................................... 59
RETURN..................................................................... 60
RLF............................................................................. 60
RRF............................................................................ 60
SLEEP........................................................................ 60
SUBLW....................................................................... 61
SUBWF....................................................................... 61
SWAPF....................................................................... 62
TRIS ........................................................................... 62
XORLW ...................................................................... 62
XORWF...................................................................... 62
Instruction Set Summary .................................................... 51
INT Interrupt ....................................................................... 46
INTCON Register ............................................................... 19
Interrupts ............................................................................ 45
IORLW Instruction .............................................................. 57
IORWF Instruction.............................................................. 58
K
KeeLoq Evaluation and Programming Tools................... 65
M
MOVF Instruction................................................................ 58
MOVLW Instruction ............................................................ 58
MOVWF Instruction ............................................................ 58
MP-DriveWay™ - Application Code Generator .................. 65
MPLAB C............................................................................ 65
MPLAB Integrated Development Environment Software.... 64
N
NOP Instruction .................................................................. 59
O
One-Time-Programmable (OTP) Devices .............................7
OPTION Instruction ............................................................ 59
OPTION Register ............................................................... 18
Oscillator Configurations .................................................... 37
Oscillator Start-up Timer (OST).......................................... 40
P
Package Marking Information............................................. 86
Packaging Information........................................................ 79
PCL and PCLATH .............................................................. 21
PCON Register................................................................... 20
PICDEM-1 Low-Cost PICmicro Demo Board ..................... 64
PICDEM-2 Low-Cost PIC16CXX Demo Board................... 64
PICDEM-3 Low-Cost PIC16CXXX Demo Board ................ 64
PICMASTER In-Circuit Emulator..................................... 63
PICSTART Plus Entry Level Development System......... 63
Pinout Description .............................................................. 11
Port RB Interrupt................................................................. 46
PORTA ............................................................................... 23
PORTB ............................................................................... 25
Power Control/Status Register (PCON) ............................. 41
Power-Down Mode (SLEEP).............................................. 49
PIC16C55X(A)
DS40143B-page 90 Preliminary 1997 Microchip Technology Inc.
Power-On Reset (POR) ......................................................40
Power-up Timer (PWRT).....................................................40
Prescaler.............................................................................32
PRO MATE II Universal Programmer...............................63
Program Memory Organization...........................................13
Q
Quick-Turnaround-Production (QTP) Devices......................7
R
RC Oscillator.......................................................................38
Reset................................................................................... 39
RETFIE Instruction.............................................................. 59
RETLW Instruction..............................................................59
RETURN Instruction............................................................60
RLF Instruction.................................................................... 60
RRF Instruction...................................................................60
S
SEEVAL Evaluation and Programming System...............65
Serialized Quick-Turnaround-Production (SQTP) Devices...7
SLEEP Instruction...............................................................60
Software Simulator (MPLAB-SIM).......................................65
Special Features of the CPU...............................................35
Special Function Registers .................................................16
Stack...................................................................................21
Status Register....................................................................17
SUBLW Instruction.............................................................. 61
SUBWF Instruction..............................................................61
SWAPF Instruction.............................................................. 62
T
Timer0
TIMER0.......................................................................29
TIMER0 (TMR0) Interrupt........................................... 29
TIMER0 (TMR0) Module.............................................29
TMR0 with External Clock...........................................31
Timer1
Switching Prescaler Assignment.................................33
Timing Diagrams and Specifications................................... 74
TMR0 Interrupt....................................................................46
TRIS Instruction ..................................................................62
TRISA..................................................................................23
TRISB..................................................................................25
W
Watchdog Timer (WDT)......................................................47
X
XORLW Instruction .............................................................62
XORWF Instruction.............................................................62
LIST OF EXAMPLES
Example 3-1: Instruction Pipeline Flow.................... 12
Example 4-1: Ndirect Addressing............................. 22
Example 5-1: Read-Modify-Write Instructions
on an I/O Port..................................... 27
Example 6-1: Changing Prescaler
(Timer0→WDT)...................................33
Example 6-2: Changing prescaler
(WDT→Timer0)...................................33
Example 7-1: Saving the Status and W Registers
in RAM .............................................47
LIST OF FIGURES
Figure 3-1: BlocK Diagram ........................................... 10
Figure 3-2: Clock/Instruction Cycle............................... 12
Figure 4-1: Program Memory Map and Stack for the
PIC16C554/PIC6C554(A) .......................... 13
Figure 4-2: Program Memory Map and Stack for the
PIC16C556(A)............................................ 13
Figure 4-3: Program Memory Map and Stack for the
PIC16C558/PIC16C558(A) ........................ 13
Figure 4-4: Data Memory Map for the
PIC16C554/554(A)..................................... 15
Figure 4-5: Data Memory Map for the
PIC16C558/558(A)..................................... 15
Figure 4-6: STATUS Register (Address
03h or 83h)................................................. 17
Figure 4-7: OPTION Register (address 81h)................ 18
Figure 4-8: INTCON Register (address 0Bh
or 8Bh)........................................................ 19
Figure 4-9: PCON Register (Address 8Eh)................... 20
Figure 4-10: Loading Of PC In Different Situations ........ 21
Figure 4-11: Direct/indirect Addressing
PIC16C55X(A)............................................ 22
Figure 5-1: Block Diagram of
PORT pins RA<3:0>................................... 23
Figure 5-2: Block Diagram of RA4 Pin.......................... 23
Figure 5-3: Block Diagram of RB7:RB4 Pins................ 25
Figure 5-4: Block Diagram of RB3:RB0 Pins................ 25
Figure 5-5: Successive I/O Operation........................... 27
Figure 6-1: TIMER0 Block Diagram.............................. 29
Figure 6-2: TIMER0 (TMR0) Timing: Internal
Clock/No PrescaleR ................................... 29
Figure 6-3: TIMER0 Timing: Internal Clock/
Prescale 1:2 ............................................... 30
Figure 6-4: TIMER0 Interrupt Timing............................ 30
Figure 6-5: TIMER0 Timing With External Clock.......... 31
Figure 6-6: Block Diagram of thE Timer0/WDT
Prescaler .................................................... 32
Figure 7-1: Configuration Word .................................... 36
Figure 7-2: Crystal Operation (or Ceramic Resonator)
(HS, XT or LP Osc Configuration).............. 37
Figure 7-3: External Clock Input Operation
(HS, XT or LP Osc Configuration).............. 37
Figure 7-4: External Parallel Resonant Crystal
Oscillator Circuit ......................................... 38
Figure 7-5: External Series Resonant Crystal
Oscillator Circuit ......................................... 38
Figure 7-6: RC Oscillator Mode .................................... 38
Figure 7-7: Simplified Block Diagram of On-chip
Reset Circuit............................................... 39
Figure 7-8: Time-out Sequence on Power-up
(MCLR
not tied to VDD): Case 1................. 43
Figure 7-9: Time-out Sequence on Power-up
(MCLR not tied to VDD): Case 2................. 43
Figure 7-10: Time-out Sequence on Power-up
(MCLR tied to VDD)..................................... 43
Figure 7-11: External Power-on Reset Circuit
(For Slow VDD Power-up)........................... 44
Figure 7-12: Interrupt Logic ............................................ 45
Figure 7-13: INT Pin Interrupt Timing ............................. 46
Figure 7-14: Watchdog Timer Block Diagram................. 48
Figure 7-15: Summary of Watchdog Timer
Registers .................................................... 48
Figure 7-16: Wake-up from Sleep Through
Interrupt...................................................... 49
Figure 7-17: Typical In-Circuit Serial Programming
Connection ................................................. 50
1997 Microchip Technology Inc. Preliminary DS40143B-page 91
PIC16C55X(A)
Figure 8-1: General Format for Instructions.................. 51
Figure 10-1: Load Conditions.......................................... 73
Figure 10-2: External Clock Timing................................. 74
Figure 10-3: CLKOUT and I/O Timing.............................75
Figure 10-4: Reset, Watchdog Timer, Oscillator
Start-Up Timer and Power-Up Timer
Timing.........................................................76
Figure 10-5: TIMER0 Clock Timing................................. 77
Figure 10-6: Load Conditions.......................................... 77
LIST OF TABLES
Table 1-1: PIC16C55X(A) Family of Devices.......... 6
Table 3-1: PIC16C55X(A) Pinout Description....... 11
Table 4-1: Special Registers for the
PIC16C55X(A)..................................... 16
Table 5-1: PORTA Functions................................ 24
Table 5-2: Summary of Registers Associated
With PORTA ........................................ 24
Table 5-3: PORTB Functions................................ 26
Table 5-4: Summary of Registers Associated
with PORTB......................................... 26
Table 6-1: Registers Associated with Timer0........ 33
Table 7-1: Capacitor Selection for Ceramic
Resonators (Preliminary)..................... 37
Table 7-2: Capacitor Selection for Crystal
Oscillator (Preliminary)......................... 37
Table 7-3: Time-out in Various Situations............. 41
Table 7-4: StatUs Bits and Their Significance....... 41
Table 7-5: Initialization Condition for Special
Registers.............................................. 42
Table 7-6: Initialization Condition for Registers..... 42
Table 8-1: OPCODE Field Descriptions................ 51
Table 8-2: PIC16C55X(A) Instruction SeT............ 52
Table 9-1: Development Tools From Microchip.... 66
Table 10-1: Cross Reference of Device Specs
for Oscillator Configurations and
Frequencies of Operation
(Commercial Devices).......................... 67
Table 10-2: External Clock Timing
Requirements....................................... 74
Table 10-3: CLKOUT and I/O Timing
Requirements....................................... 75
Table 10-4: Reset, Watchdog Timer, Oscillator
Start-up Timer and Power-up Timer
Requirements....................................... 76
Table 10-5: TIMER0 Clock Requirements .............. 77
PIC16C55X(A)
DS40143B-page 92 Preliminary 1997 Microchip Technology Inc.
NOTES:
1997 Microchip Technology Inc. Preliminary DS40143B-page 93
PIC16C55X(A)
ON-LINE SUPPORT
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960513
PIC16C55X(A)
DS40143B-page 94 Preliminary 1997 Microchip Technology Inc.
READER RESPONSE
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DS40143B
PIC16C55X(A)
1997 Microchip Technology Inc. Preliminary DS40143B-page 95
PIC16C55X(A)
PIC16C55X(A) Product Identification System
To order or to obtain information, e.g., on pricing or delivery, please use the listed part numbers, and refer to the factory or the listed
sales offices.
* JW Devices are UV erasable and can be programmed to any device configuration. JW Devices meet the electrical requirement of
each oscillator type (including LC devices).
Pattern: 3-Digit Pattern Code for QTP (blank otherwise)
Package: P = PDIP
SO = SOIC (Gull Wing, 300 mil body)
SS = SSOP (209 mil)
JW* = Windowed CERDIP
Temperature - = 0˚C to +70˚C
Range: I = –40˚C to +85˚C
E = –40˚C to +125˚C
Frequency 04 = 200kHz (LP osc)
Range: 04 = 4 MHz (XT and RC osc)
20 = 20 MHz (HS osc)
Device: PIC16C55X :VDD range 3.0V to 5.5V
PIC16C55XT:VDD range 3.0V to 5.5V (Tape and Reel)
PIC16C55XA: VDD range 3.0V to 5.5V
PIC16C55XAT: VDD range 3.0V to 5.5V (Tape and Reel)
PIC16LC55X:VDD range 2.5V to 5.5V
PIC16LC55XT:VDD range 2.5V to 5.5V (Tape and Reel)
Examples:
f) PIC16C554A - 04/P 301 =
Commercial temp., PDIP package, 4 MHz, normal V
DD limits,
QTP pattern #301.
g) PIC16LC558- 04I/SO =
Industrial temp., SOIC package, 200kHz, extended V
DD
limits.
PART NO
. -XX X
/XX
XXX
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DS40143B-page 96 1997 Microchip Technology Inc.
M
All rights reserved. © 1997, Microchip Technology Incorporated, USA. 9/97 Printed on recycled paper.
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