PIC ASSEMBLER NOTES
The PIC 12,14,16, and 17 series of processors uses a non unified
addressing scheme: the instruction addressing is 1 per
instruction word, each instruction uses a word of memory varying
from 12 to 16 bits in length. The processor data is addressed
as 1 per byte of data. To properly address the program/data
spaces you, the programmer, must seperate your program and data
into seperate code and data areas. The data area is addressed
as 1 per byte and the code area is addressed as 1 per
instruction. The assembler/linker processes the instruction
code so that the linker will output 2 bytes for each instruction
word. The instruction word address will be the file encoded
address divided by 2.
The pic 18 series of processors uses a unified addressing
scheme: the instruction and data addressing is 1 per 8-bit byte.
The assembler/linker processes the instruction code so that the
linker will output 2 bytes for each instruction word. The byte
ordering is low-byte then high-byte and the program address
is the the file encoded address.
PROCESSOR SPECIFIC DIRECTIVES
The ASPIC assembler has several processor specific assem-
bler directives. These directives specify a processor name,
select a PIC processor family type, define the maximum ram ad-
dress, specify ram addresses that should not be accessed, and
define the register file address page.
Format:
.pic "string"
The assembler uses the delimited string to define a proces-
sor specific symbol. e.g: "p12c508" produces the symbol
__12c508 having a value of 1. This symbol can then be used in
an .ifdef/.else/.endif construct.
The assembler should be configured by including directives
similiar to the folowing at the beginning of your assembly file:
.pic "p12c508" ; Set PIC Name
.pic12bit ; Select PIC Type
The ASPIC assembler will then be configured for the PIC
processor type "p12c508". The .pic directive must precede the
PIC type directive. The PIC type directive configures the as-
sembler base on the processor name and type selection.
An alternate method to configure the ASPIC assembler is as
follows:
.pic "p12c508" ; Set PIC Name
.include "piccpu.def" ; Selects PIC Type
To define the special function register names, bit values,
and memory constraints for a specific processor include the
appropriate definition file:
.include "p12c508.def" ; Definitions
Format:
.picnopic
This directive deselects all processor specific mnemonics.
Format:
.pic12bit
This directive selects the 12-bit instruction word mnemon-
ics and opcode values to be used during the assembly process.
Format:
.pic14bit
This directive selects the 14-bit instruction word mnemon-
ics and opcode values to be used during the assembly process.
Format:
.pic16bit
This directive selects the 16-bit instruction word mnemon-
ics and opcode values to be used during the assembly process.
Format:
.pic20bit
This directive selects 20-bit addressing and the 16-bit in-
struction word mnemonics and opcode values to be used during the
assembly process.
Format:
.picgoto (optional argument)
This directive selects the PIC or ASxxxx mode of CALL, GOTO
and Branching argument processing. The default ASxxxx mode,
specified by a zero valued argument, processes the instruction
arguments as regular labels (with relocation if required).
A blank or non-zero argument invokes the PIC mode. The PIC
mode inserts the value of the instruction argument directly into
the instruction without further processing.
The .__.CPU. Variable
The value of the pre-defined symbol '.__.CPU.' corresponds
to the selected processor type. The default value is 0 which
corresponds to the default processor type. The following table
lists the processor types and associated values for the ASPIC
assembler:
Processor Type .__.CPU. Value
-------------- --------------
.picnopic 0
.pic12bit 1
.pic14bit 2
.pic16bit 3
.pic20bit 4
The variable '.__.CPU.' is by default defined as local and
will not be output to the created .rel file. The assembler com-
mand line options -g or -a will not cause the local symbol to be
output to the created .rel file.
The assembler .globl directive may be used to change the
variable type to global causing its definition to be output
to the .rel file. The inclusion of the definition of the vari-
able '.__.CPU.' might be a useful means of validating that
seperately assembled files have been compiled for the same pro-
cessor type. The linker will report an error for variables with
multiple non equal definitions.
Format:
.picfix chip, mnemonic, value
This directive can be used to "fix" or change the opcode
value of any pic instruction of the currently selected pic type.
e.g.:
.picfix "p12c671", "clrw", 0x0103
will change the "clrw" instruction's opcode to 0x0103 if the
current pic type is "p12c671".
Format:
.maxram value
Where value is the highest allowed ram address
Format:
.badram address
.badram lo:hi
Where address is a single location and lo:hi is a range of
addresses that should not be used. Multiple locations and/or
ranges may be specified by seperating the arguments with a
comma:
.badram 0x23, 0x28:0x2F, ...
The ASPIC assembler will report an error for any absolute
register file address in the badram range.
Format:
.setdmm value
The .setdmm (set Data Memory Map) directive is used to in-
form the assembler and linker about which ram bank has been
selected for access. The PIC17Cxxx microprocessor family allows
upto 2 (or more) banks of 256 byte ram blocks. The PIC18Cxxx
microprocessor family allows upto 16 banks of 256 byte ram
blocks. The data memory map value must be set on a 256 byte
boundary. e.g.:
.setdmm 0x0F00
The assembler verifies that any absolute address to the
register file is within the 256 byte page. External direct
references are assumed by the assembler to be in the correct
area and have valid offsets. The linker will check all page
relocations to verify that they are within the correct address-
ing range.
12-BIT OPCODE PIC
The 12-bit opcode family of PIC processors support the following
assembler arguments:
(*)f
(*)f,(#)d
(*)f,(#)b
(#)k
label
where: f register file address
d destination select:
(0, -> w), (1 -> f)
the letters w or f may be used
to select the destination
b bit address in an 8-bit file register
k literal constant
label label name
Items enclosed in () are optional.
The terms f, d, b, k, and label may all be expressions.
Note that not all addressing modes are valid with every in-
struction, refer to the processor specific technical data for
valid modes.
PIC12C5XX CPU Type
PIC12C508, PIC12C509, PIC12CE518
PIC12C508A, PIC12C509A, PIC12CE519
PIC12CR509A
14-BIT OPCODE PIC
The 14-bit opcode family of PIC processors support the following
assembler arguments:
(*)f
(*)f,(#)d
(*)f,(#)b
(#)k
label
where: f register file address
d destination select:
(0, -> w), (1 -> f)
the letters w or f may be used
to select the destination
b bit address in an 8-bit file register
k literal constant
label label name
Items enclosed in () are optional.
The terms f, d, b, k, and label may all be expressions.
Note that not all addressing modes are valid with every in-
struction, refer to the processor specific technical data for
valid modes.
PIC12C67X CPU Type
PIC12C671, PIC12C672, PIC12LC671,
PIC12LC672
PIC12CE673, PIC12CE674, PIC12LCE673,
PIC12LCE674
PIC14000 CPU Type
PIC14000
PIC16C15X CPU Type
PIC16C154, PIC16C156, PIC16C158
PIC16CR154, PIC16CR156, PIC16CR158
PIC16C5X CPU Type
PIC16C52
PIC16C54, PICC16C54A, PIC16C54B,
PIC16C54C
PIC16CR54, PIC16CR54A, PIC16C54B,
PIC16CR54C
PIC16C55, PIC16C55A, PIC16C56,
PIC16C56A
PIC16CR56A
PIC16C57, PIC16CR57A, PIC16C57B,
PIC16C57C
PIC16C58A, PIC16CR58A, PIC16C58B,
PIC16CR58B
PIC16C55X CPU Type
PIC16C554, PIC16C556, PIC16C558
PIC16C62X, PIC16C64X and, PIC16C66X CPU Types
PIC16C620, PIC16C621, PIC16C622
PIC16C642, PIC16C662
PIC16C7XX CPU Type
PIC16C71, PIC16C72, PIC16CR72
PIC16C73A, PIC16C74A, PIC16C76, PIC16C77
PIC16C710, PIC16C711, PIC16C715
PIC16C8X CPU Type
PIC16F83, PIC16CR83, PIC16F84,
PIC16CR84
PIC16HV540
PIC16F627, PIC16F628
PIC16F870, PIC16F871, PIC16F872,
PIC16F873
PIC16F874, PIC16F876, PIC16F877
PIC16C9XX CPU Type
PIC16C923, PIC16C924
16-BIT OPCODE PIC
The 16-bit opcode family of PIC processors support the following
assembler arguments:
(*)f
(*)f,(#)d
(*)f,(#)s
(*)f,(#)b
(*)f,(*)p / (*)p,(*)f
(#)t,(*)f
(#)t,(#)i,(*)f
{#}k
label
where: f register file address
d destination select:
(0, -> w), (1 -> f)
the letters w or f may be used
to select the destination
s destination select:
(0, -> f and w), (1, -> f)
the letters w or f may be used
to select the destination
t table byte select:
(0, -> lower byte)
(1, -> upper byte)
i table pointer control
(0, -> no change)
(1, -> post increment)
b bit address of an 8-bit file register
p peripheral register file address
k literal constant
label label name
Items enclosed in () are optional.
The terms f, d, s, t, i, b, p, k, and label may all be
expressions.
Note that not all addressing modes are valid with every in-
struction, refer to the processor specific technical data for
valid modes.
PIC17CXXX CPU Type
PIC17C42, PIC17C42A, PIC17C43, PIC17C44
PIC17C752, PIC17C756, PIC17C756A
PIC17C762, PIC17C766, PIC17CR42,
PIC17CR43
20-BIT ADDRESSING PIC
The 20-bit addressing family of PIC processors support the
following assembler arguments:
(*)f(,a)
(*)f,(#)d(,(#)a)
(*)f,(#)s
(*)f,(#)b(,(#)a)
(*)fs,(*)fd
(#)t,(*)f
(#)t,(#)i,(*)f
{#}k
label(,(#)s)
((#)s)
mm
where: f register file address
fs register file source
fd register file destination
a ram access bit
(0, -> ACCESS RAM)
(1, -> RAM BANK)
d destination select:
(0, -> w), (1 -> f)
the letters w or f may be used
to select the destination
s fast call/return mode:
(0, -> SLOW), (1, -> FAST)
b bit address of an 8-bit file register
mm TBLRD and TBLWT suffixs
('*', -> no change)
('*+', -> post-increment)
('*-', -> post-decrement)
('+*', -> pre-increment)
k literal constant
label label name
Items enclosed in () are optional.
The terms f, fs, fd, a, b, d, s, k, and label may all be
expressions.
Note that not all addressing modes are valid with every in-
struction, refer to the processor specific technical data for
valid modes.
PIC18CXXX CPU Type
PIC18C242, PIC18C252
PIC18C442, PIC18C452
PIC18C658, PIC18C858
PIC OPCODES
The following table contains all the mnemonics recognized
by the ASPIC assembler. The processors supporting each mnemonic
are indicated by the code 'PIC:12:14:16:20' after each instruc-
tion type. The designation [] refers to a required addressing
mode argument.
addwf [] PIC:12:14:16:20
addwfc [] PIC:--:--:16:20
andwf [] PIC:12:14:16:20
comf [] PIC:12:14:16:20
decf [] PIC:12:14:16:20
decfsz [] PIC:12:14:16:20
dcfsnz [] PIC:--:--:16:20
incf [] PIC:12:14:16:20
incfsz [] PIC:12:14:16:20
infsnz [] PIC:--:--:16:20
iorwf [] PIC:12:14:16:20
movf [] PIC:12:14:--:20
negw [] PIC:--:--:16:--
rlf [] PIC:12:14:--:--
rlcf [] PIC:--:--:16:20
rlncf [] PIC:--:--:16:20
rrf [] PIC:12:14:--:--
rrcf [] PIC:--:--:16:20
rrncf [] PIC:--:--:16:20
subfwb [] PIC:--:--:--:20
subwf [] PIC:12:14:16:20
subwfb [] PIC:--:--:16:20
swapf [] PIC:12:14:16:20
xorwf [] PIC:12:14:16:20
movfp [] PIC:--:--:16:--
movpf [] PIC:--:--:16:--
movlb [] PIC:--:--:16:20
movlr [] PIC:--:--:16:--
movff [] PIC:--:--:--:20
lfsr [] PIC:--:--:--:20
clrf [] PIC:12:14:16:20
cpfseq [] PIC:--:--:16:20
cpfsgt [] PIC:--:--:16:20
cpfslt [] PIC:--:--:16:20
movwf [] PIC:12:14:16:20
mulwf [] PIC:--:--:16:20
negf [] PIC:--:--:--:20
setf [] PIC:--:--:16:20
tstfsz [] PIC:--:--:16:20
bcf [] PIC:12:14:16:20
bsf [] PIC:12:14:16:20
btfsc [] PIC:12:14:16:20
btfss [] PIC:12:14:16:20
btg [] PIC:--:--:16:20
addlw [] PIC:--:14:16:20
andlw [] PIC:12:14:16:20
iorlw [] PIC:12:14:16:20
movlw [] PIC:12:14:16:20
mullw [] PIC:--:--:16:20
retlw [] PIC:12:14:16:20
sublw [] PIC:--:14:16:20
xorlw [] PIC:12:14:16:20
call [] PIC:12:14:16:20
goto [] PIC:12:14:16:20
lcall [] PIC:--:--:16:--
bc [] PIC:--:--:--:20
bn [] PIC:--:--:--:20
bnc [] PIC:--:--:--:20
bnn [] PIC:--:--:--:20
bnov [] PIC:--:--:--:20
bnc [] PIC:--:--:--:20
bov [] PIC:--:--:--:20
bz [] PIC:--:--:--:20
bra [] PIC:--:--:--:20
rcall [] PIC:--:--:--:20
tablrd [] PIC:--:--:16:--
tablwt [] PIC:--:--:16:--
tlrd [] PIC:--:--:16:--
tlwt [] PIC:--:--:16:--
tblrd [] PIC:--:--:--:20
tblwt [] PIC:--:--:--:20
clrw [] PIC:12:14:--:--
clrwdt PIC:12:14:16:20
daw PIC:--:--:16:20
nop PIC:12:14:16:20
option PIC:12:14:--:--
pop PIC:--:--:--:20
push PIC:--:--:--:20
retfie [] PIC:--:14:16:20
return [] PIC:--:14:16:20
sleep PIC:12:14:16:20
tris [] PIC:12:14:--:--
addfsr [] PIC:--:--:--:20
addulnk [] PIC:--:--:--:20
callw PIC:--:--:--:20
movsf [] PIC:--:--:--:20
movss [] PIC:--:--:--:20
pushl [] PIC:--:--:--:20
subfsr [] PIC:--:--:--:20
subulnk [] PIC:--:--:--:20
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Last Updated: March 2007