Datasheet

PIC18F2220/2320/4220/4320
DS39599G-page 270 © 2007 Microchip Technology Inc.
BTFSC Bit Test File, Skip if Clear
Syntax: [ label ] BTFSC f,b[,a]
Operands: 0 ≤ f ≤ 255
0 ≤ b ≤ 7
a ∈ [0,1]
Operation: skip if (f<b>) = 0
Status Affected: None
Encoding:
1011 bbba ffff ffff
Description: If bit ‘b’ in register ‘f’ is ‘0’, then the
next instruction is skipped.
If bit ‘b’ is ‘0’, then the next instruc-
tion fetched during the current
instruction execution is discarded
and a NOP is executed instead, mak-
ing this a two-cycle instruction. If ‘a’
is ‘0’, the Access Bank will be
selected, overriding the BSR value. If
‘a’ = 1, then the bank will be selected
as per the BSR value (default).
Words: 1
Cycles: 1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register ‘f’
Process Data No
operation
If skip:
Q1 Q2 Q3 Q4
No
operation
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1 Q2 Q3 Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE
FALSE
TRUE
BTFSC
:
:
FLAG, 1
Before Instruction
PC = address (HERE)
After Instruction
If FLAG<1> = 0;
PC = address (TRUE)
If FLAG<1> = 1;
PC = address (FALSE)
BTFSS Bit Test File, Skip if Set
Syntax: [ label ] BTFSS f,b[,a]
Operands: 0 ≤ f ≤ 255
0 ≤ b < 7
a ∈ [0,1]
Operation: skip if (f<b>) = 1
Status Affected: None
Encoding:
1010 bbba ffff ffff
Description: If bit ‘b’ in register ‘f’ is ‘1’, then the
next instruction is skipped.
If bit ‘b’ is ‘1’, then the next instruc-
tion fetched during the current
instruction execution is discarded
and a NOP is executed instead, mak-
ing this a two-cycle instruction. If ‘a’
is ‘0’, the Access Bank will be
selected, overriding the BSR value. If
‘a’ = 1, then the bank will be selected
as per the BSR value (default).
Words: 1
Cycles: 1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register ‘f’
Process Data No
operation
If skip:
Q1 Q2 Q3 Q4
No
operation
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1 Q2 Q3 Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE
FALSE
TRUE
BTFSS
:
:
FLAG, 1
Before Instruction
PC = address (HERE)
After Instruction
If FLAG<1> = 0;
PC = address (FALSE)
If FLAG<1> = 1;
PC = address (TRUE)