Datasheet

 1996 Microchip Technology Inc. DS30430B-page 55
PIC16F8X
9.0 INSTRUCTION SET SUMMARY
Each PIC16FXX instruction is a 14-bit word divided into
an OPCODE which specifies the instruction type and
one or more operands which further specify the opera-
tion of the instruction. The PIC16FXX instruction set
summary in Table 9-2 lists byte-oriented, bit-oriented,
and literal and control operations. Table 9-1 shows the
opcode field descriptions.
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 0, the result is
placed in the W register. If 'd' is 1, the result is placed in
the file register specified by the instruction.
Bit-oriented instructions: 'b' represents a bit field
designator which selects the number of the bit affected
by the operation, while 'f' represents the address of the
file in which the bit is located.
Literal and control operations: 'k' represents an eight
or eleven bit constant or literal value.
TABLE 9-1: 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
• Bit-oriented
• Literal and control
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 the instruction. The
execution takes two instruction cycles with the second
cycle executed as a NOP. Each cycle consists of four
oscillator periods. Thus, for an oscillator frequency of
4 MHz, the normal instruction execution time is 1 µ s.
The instruction execution time is 2 µ s for program
branches.
Table 9-2 lists the instructions recognized by
Microchip’s assembler (MPASM).
Figure 9-1 shows the three general formats of
instructions.
All examples use the following format to represent a
hexadecimal number:
0xhh
where h signifies a hexadecimal digit.
FIGURE 9-1: GENERAL FORMAT FOR
INSTRUCTIONS
Note: To maintain upward compatibility with
future PIC16FXX 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
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