PIC18F2420/2520/4420/4520
TABLE 24-1: OPCODE FIELD DESCRIPTIONS
Field
Description
a
RAM access bit
a = 0: RAM location in Access RAM (BSR register is ignored)
a = 1: RAM bank is specified by BSR register
bbb
BSR
Bit address within an 8-bit file register (0 to 7).
Bank Select Register. Used to select the current RAM bank.
ALU Status bits: Carry, Digit Carry, Zero, Overflow, Negative.
C, DC, Z, OV, N
d
Destination select bit
d = 0: store result in WREG
d = 1: store result in file register f
dest
f
Destination: either the WREG register or the specified register file location.
8-bit Register file address (00h to FFh) or 2-bit FSR designator (0h to 3h).
12-bit Register file address (000h to FFFh). This is the source address.
12-bit Register file address (000h to FFFh). This is the destination address.
Global Interrupt Enable bit.
f
f
s
d
GIE
k
Literal field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value).
Label name.
label
mm
The mode of the TBLPTR register for the table read and table write instructions.
Only used with table read and table write instructions:
*
No change to register (such as TBLPTR with table reads and writes)
Post-Increment register (such as TBLPTR with table reads and writes)
Post-Decrement register (such as TBLPTR with table reads and writes)
Pre-Increment register (such as TBLPTR with table reads and writes)
*+
*-
+*
n
The relative address (2’s complement number) for relative branch instructions or the direct address for
Call/Branch and Return instructions.
PC
Program Counter.
PCL
Program Counter Low Byte.
Program Counter High Byte.
Program Counter High Byte Latch.
Program Counter Upper Byte Latch.
Power-down bit.
PCH
PCLATH
PCLATU
PD
PRODH
PRODL
s
Product of Multiply High Byte.
Product of Multiply Low Byte.
Fast Call/Return mode select bit
s = 0: do not update into/from shadow registers
s = 1: certain registers loaded into/from shadow registers (Fast mode)
TBLPTR
TABLAT
TO
21-bit Table Pointer (points to a Program Memory location).
8-bit Table Latch.
Time-out bit.
TOS
u
Top-of-Stack.
Unused or unchanged.
Watchdog Timer.
WDT
WREG
x
Working register (accumulator).
Don’t care (‘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.
z
z
{
7-bit offset value for indirect addressing of register files (source).
7-bit offset value for indirect addressing of register files (destination).
Optional argument.
s
d
}
[text]
(text)
[expr]<n>
→
Indicates an indexed address.
The contents of text.
Specifies bit nof the register indicated by the pointer expr.
Assigned to.
< >
Register bit field.
∈
In the set of.
italics
User-defined term (font is Courier New).
DS39631E-page 268
© 2008 Microchip Technology Inc.
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