PIC18F2420/2520/4420/4520
BTG
Bit Toggle f
BOV
Branch if Overflow
Syntax:
BTG f, b {,a}
Syntax:
BOV
n
Operands:
0 ≤ f ≤ 255
0 ≤ b < 7
a ∈ [0,1]
Operands:
Operation:
-128 ≤ n ≤ 127
if Overflow bit is ‘1’,
(PC) + 2 + 2n → PC
Operation:
(f<b>) → f<b>
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1110
0100
nnnn
nnnn
0111
bbba
ffff
ffff
Description:
If the Overflow bit is ‘1’, then the
Description:
Bit ‘b’ in data memory location ‘f’ is
inverted.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
program will branch.
The 2’s complement number, ‘2n’, is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
Cycles:
1
1(2)
Q Cycle Activity:
If Jump:
Words:
Cycles:
1
1
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Q Cycle Activity:
Q1
No
operation
No
operation
No
operation
No
operation
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
If No Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
BTG
PORTC, 4, 0
Before Instruction:
PORTC
After Instruction:
PORTC
=
0111 0101 [75h]
0110 0101 [65h]
Example:
HERE
BOV Jump
Before Instruction
=
PC
=
address (HERE)
After Instruction
If Overflow
PC
If Overflow
PC
=
=
=
=
1;
address (Jump)
0;
address (HERE + 2)
© 2008 Microchip Technology Inc.
DS39631E-page 281
MICROCHIP [ MICROCHIP ]
