PIC18F2331/2431/4331/4431
BTFSC
Bit Test File, Skip if Clear
BTFSS
Bit Test File, Skip if Set
Syntax:
[ label ] BTFSC f,b[,a]
Syntax:
[ label ] BTFSS f,b[,a]
Operands:
0 f 255
0 b 7
a [0,1]
Operands:
0 f 255
0 b < 7
a [0,1]
Operation:
skip if (f<b>) = 0
Operation:
skip if (f<b>) = 1
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1011
bbba
ffff
ffff
1010
bbba
ffff
ffff
Description:
If bit ‘b’ in register, ‘f’, is ‘0’, then the next
instruction is skipped.
Description:
If bit ‘b’ in register, ‘f’, is ‘1’, then the next
instruction is skipped.
If bit ‘b’ is ‘0’, then the next instruction
fetched during the current instruction
execution is discarded, and a NOPis
executed instead, making 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.
If bit ‘b’ is ‘1’, then the next instruction
fetched during the current instruction
execution, is discarded and a NOPis
executed instead, making 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.
Words:
Cycles:
1
Words:
Cycles:
1
1(2)
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Note:
3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
Decode
Read
register ‘f’
Process
Data
No
operation
If skip:
Q1
If skip:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
Example:
HERE
FALSE
TRUE
BTFSC
:
:
FLAG, 1
Example:
HERE
FALSE
TRUE
BTFSS
:
:
FLAG, 1
Before Instruction
PC
Before Instruction
PC
=
address (HERE)
=
address (HERE)
After Instruction
If FLAG<1>
PC
After Instruction
If FLAG<1>
PC
=
=
=
=
0;
=
=
=
=
0;
address (TRUE)
1;
address (FALSE)
address (FALSE)
1;
address (TRUE)
If FLAG<1>
PC
If FLAG<1>
PC
DS39616D-page 296
2010 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
