PIC16F870/871
12.0
INSTRUCTION SET SUMMARY
Each PIC16CXX 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 PIC16CXX instruction
set summary in Table 12-2 lists
byte-oriented, bit-ori-
ented,
and
literal and control
operations. Table 12-1
shows the opcode field descriptions.
For
byte-oriented
instructions, ’f’ represents a file reg-
ister designator and ’d’ represents a destination desig-
nator. 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.
execution time is 1
µs.
If a conditional test is true or the
program counter is changed as a result of an instruc-
tion, the instruction execution time is 2
µs.
MPASM assembler.
tions can have.
Note:
To maintain upward compatibility with
future PIC16CXX products, do not use the
OPTION
and
TRIS
instructions.
All examples use the following format to represent a
hexadecimal number:
0xhh
where h signifies a hexadecimal digit.
FIGURE 12-1: GENERAL FORMAT FOR
INSTRUCTIONS
Byte-oriented file register operations
13
8 7 6
OPCODE
d
f (FILE #)
d = 0 for destination W
d = 1 for destination f
f = 7-bit file register address
Bit-oriented file register operations
13
10 9
7 6
OPCODE
b (BIT #)
b = 3-bit bit address
f = 7-bit file register address
Literal and control operations
General
13
OPCODE
k = 8-bit immediate value
CALL and GOTO instructions only
13
11
OPCODE
10
k (literal)
0
8
7
k (literal)
0
0
TABLE 12-1:
Field
f
W
b
k
x
OPCODE FIELD
DESCRIPTIONS
Description
0
f (FILE #)
Register file address (0x00 to 0x7F)
Working register (accumulator)
Bit address within an 8-bit file register
Literal field, constant data or label
Don't care location (=
0
or
1)
The assembler will generate code with x =
0.
It
is the recommended form of use for compati-
bility with all Microchip software tools.
Destination select; d =
0:
store result in W,
d = 1: store result in file register f.
Default is d =
1
Program Counter
Time-out bit
Power-down bit
d
PC
TO
PD
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 instruc-
tion cycle, unless a conditional test is true or the pro-
gram 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 instruc-
tion cycle consists of four oscillator periods. Thus, for
an oscillator frequency of 4 MHz, the normal instruction
k = 11-bit immediate value
A description of each instruction is available in the
PICmicro™
Mid-Range
Reference
Manual,
(DS33023).
©
1999 Microchip Technology Inc.
Preliminary
DS30569A-page 105
MICROCHIP [ MICROCHIP TECHNOLOGY ]
