PIC12F508/509/16F505
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. In this
case, the execution takes two instruction cycles. 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.
8.0
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
Each PIC16 instruction is a 12-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 catego-
ries is presented in Figure 8-1, while the various
opcode fields are summarized in Table 8-1.
Figure 8-1 shows the three general formats that the
instructions can have. All examples in the figure use
the following format to represent a hexadecimal
number:
0xhhh
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.
where ‘h’ signifies a hexadecimal digit.
FIGURE 8-1:
GENERAL FORMAT FOR
INSTRUCTIONS
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 in the instruction.
Byte-oriented file register operations
11
6
5
d
4
0
OPCODE
f (FILE #)
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.
d = 0for destination W
d = 1for destination f
f = 5-bit file register address
Bit-oriented file register operations
11 8 7
b (BIT #)
For literal and control operations, ‘k’ represents an
8 or 9-bit constant or literal value.
5
4
0
OPCODE
f (FILE #)
b = 3-bit bit address
f = 5-bit file register address
TABLE 8-1:
OPCODE FIELD
DESCRIPTIONS
Literal and control operations (except GOTO)
11
Field
Description
8
7
0
f
W
b
k
x
Register file address (0x00 to 0x7F)
Working register (accumulator)
OPCODE
k (literal)
Bit address within an 8-bit file register
Literal field, constant data or label
k = 8-bit immediate value
Literal and control operations – GOTOinstruction
11
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.
9
8
0
OPCODE
k (literal)
d
Destination select;
k = 9-bit immediate value
d= 0(store result in W)
d= 1(store result in file register ‘f’)
Default is d= 1
label
TOS
PC
Label name
Top-of-Stack
Program Counter
Watchdog Timer counter
Time-out bit
WDT
TO
PD
Power-down bit
dest
Destination, either the W register or the specified
register file location
[
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Options
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Assigned to
Register bit field
In the set of
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italics User defined term (font is courier)
© 2007 Microchip Technology Inc.
Preliminary
DS41236C-page 55
MICROCHIP [ MICROCHIP ]
