PIC16F7X7
For example, a “CLRF PORTB” instruction will read
PORTB, clear all the data bits, then write the result
back to PORTB. This example would have the
unintended result that the condition that sets the RBIF
flag would be cleared for pins configured as inputs and
using the PORTB interrupt-on-change feature.
16.0 INSTRUCTION SET SUMMARY
The PIC16 instruction set is highly orthogonal and is
comprised of three basic categories:
• Byte-oriented operations
• Bit-oriented operations
• Literal and control operations
TABLE 16-1: OPCODE FIELD
DESCRIPTIONS
Each PIC16 instruction is a 14-bit word divided into an
opcode, which specifies the instruction type and one or
more operands, which further specify the operation of
the instruction. The formats for each of the categories
are presented in Figure 16-1, while the various opcode
fields are summarized in Table 16-1.
Field
Description
f
W
b
k
x
Register file address (0x00 to 0x7F)
Working register (accumulator)
Bit address within an 8-bit file register
Literal field, constant data or label
Table 13-2 lists the instructions recognized by the
MPASMTM Assembler. A complete description of each
instruction is also available in the “PICmicro® Mid-Range
MCU Family Reference Manual” (DS33023).
Don’t care location (= 0or 1).
The assembler will generate code with x = 0.
It is the recommended form of use for
compatibility with all Microchip software tools.
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.
d
Destination select; d = 0: store result in W,
d = 1: store result in file register f.
Default is d = 1.
The destination designator specifies where the result of
the operation is to be placed. If ‘d’ is zero, the result is
placed in the W register. If ‘d’ is one, the result is placed
in the file register specified in the instruction.
PC
TO
PD
Program Counter
Time-out bit
Power-Down bit
For bit-oriented instructions, ‘b’ represents a bit field
designator which selects the bit affected by the opera-
tion, while ‘f’ represents the address of the file in which
the bit is located.
FIGURE 16-1:
GENERAL FORMAT FOR
INSTRUCTIONS
For literal and control operations, ‘k’ represents an
eight or eleven-bit constant or literal value
Byte-oriented file register operations
13
8
7
6
0
One instruction cycle consists of four oscillator periods;
for an oscillator frequency of 4 MHz, this gives a normal
instruction execution time of 1 µs. All instructions are
executed within a single instruction cycle, unless a
conditional test is true, or the program counter is
changed as a result of an instruction. When this occurs,
the execution takes two instruction cycles, with the
second cycle executed as a NOP.
OPCODE
d
f (FILE #)
d = 0for destination W
d = 1for destination f
f = 7-bit file register address
Bit-oriented file register operations
13 10 9
b (BIT #)
7
6
0
OPCODE
f (FILE #)
Note:
To maintain upward compatibility with
future PIC16F7X7 products, do not use
the OPTIONand TRISinstructions.
b = 3-bit bit address
f = 7-bit file register address
All instruction examples use the format ‘0xhh’ to
represent a hexadecimal number, where ‘h’ signifies a
hexadecimal digit.
Literal and control operations
General
13
8
7
0
0
OPCODE
k (literal)
16.1 Read-Modify-Write Operations
k = 8-bit immediate value
Any instruction that specifies a file register as part of
the instruction performs a Read-Modify-Write (R-M-W)
operation. The register is read, the data is modified and
the result is stored according to either the instruction or
the destination designator ‘d’. A read operation is
performed on a register even if the instruction writes to
that register.
CALLand GOTOinstructions only
13 11 10
OPCODE
k = 11-bit immediate value
k (literal)
2004 Microchip Technology Inc.
DS30498C-page 193
MICROCHIP [ MICROCHIP ]
