Datasheet

 2002 Microchip Technology Inc. Preliminary DS40044A-page 111
PIC16F627A/628A/648A
15.0 INSTRUCTION SET SUMMARY
Each PIC16F627A/628A/648A instruction is a 14-bit
word divided into an OPCODE which specifies the
instruction type and one or more operands which fur-
ther specify the operation of the instruction. The
PIC16F627A/628A/648A instruction set summary in
Table 15-2 lists byte-oriented, bit-oriented, and lit-
eral and control operations. Table 15-1 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 15-1: OPCODE FIELD
DESCRIPTIONS
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 15-2 lists the instructions recognized by the
MPASM™ assembler.
Figure 15-1 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 15-1: GENERAL FORMAT FOR
INSTRUCTIONS
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 regis-
ter file location
[ ] Options
( ) Contents
→ Assigned to
< > Register bit field
∈ In the set of
italics User defined term (font is courier)
Note 1: Any unused opcode is reserved. Use of
any reserved opcode may cause unex-
pected operation.
2: To maintain upward compatibility with
future PICmicro
products, do not use the
OPTION and TRIS instructions.
Byte-oriented file register operations
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
OPCODE b (BIT #) f (FILE #)
b = 3-bit bit address
f = 7-bit file register address
Literal and control operations
OPCODE k (literal)
k = 8-bit immediate value
OPCODE k (literal)
k = 11-bit immediate value
General
CALL and GOTO instructions only
13 8 7 6 0
13 10 9 7 06
13 8 7 0
13 11 10 0