PIC18FXX20 Datasheet, PDF (274/366 Pages) Microchip Technology – 64/80-Pin High Performance 1 Mbit Enhanced FLASH Microcontrollers with A/D

PIC18FXX20
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 instruction
fetched during the current instruction
execution is discarded, and a NOP is
executed instead, making this a
two-cycle instruction. If ‘a’ is 0, the
Access Bank will be selected, over-
riding 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
Decode
Read Process Data
register 'f'
If skip:
Q1
Q2
Q3
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Q4
No
operation
Q4
No
operation
Q4
No
operation
No
operation
Example:
HERE BTFSC FLAG, 1, 0
FALSE :
TRUE :
Before Instruction
PC
= address (HERE)
After Instruction
If FLAG<1> =
PC
=
If FLAG<1> =
PC
=
0;
address (TRUE)
1;
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 instruction
fetched during the current instruc-
tion execution, is discarded and a
NOP is executed instead, making this
a two-cycle instruction. If ‘a’ is 0, the
Access Bank will be selected, over-
riding 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
Decode
Read Process Data
register 'f'
If skip:
Q1
Q2
Q3
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Q4
No
operation
Q4
No
operation
Q4
No
operation
No
operation
Example:
HERE BTFSS FLAG, 1, 0
FALSE :
TRUE :
Before Instruction
PC
= address (HERE)
After Instruction
If FLAG<1> =
PC
=
If FLAG<1> =
PC
=
0;
address (FALSE)
1;
address (TRUE)
DS39609A-page 272
Advance Information
 2003 Microchip Technology Inc.