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PIC18F258 Datasheet, PDF (289/384 Pages) Microchip Technology – High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN | |||
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PIC18FXX8
BNC
Branch if Not Carry
Syntax:
Operands:
Operation:
Status Affected:
[ label ] BNC n
-128 ⤠n ⤠127
if carry bit is â0â
(PC) + 2 + 2n â PC
None
Encoding:
Description:
1110 0011 nnnn nnnn
If the Carry bit is â0â, then the
program will branch.
The 2âs complement number â2nâ 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:
1
Cycles:
1(2)
Q Cycle Activity:
If Jump:
Q1
Q2
Decode
Read literal
ânâ
No
operation
No
operation
If No Jump:
Q1
Q2
Decode
Read literal
ânâ
Q3
Process
Data
No
operation
Q3
Process
Data
Q4
Write to PC
No
operation
Q4
No
operation
Example:
HERE
Before Instruction
PC
=
After Instruction
If Carry
=
PC
=
If Carry
=
PC
=
BNC Jump
address (HERE)
0;
address (Jump)
1;
address (HERE+2)
BNN
Branch if Not Negative
Syntax:
Operands:
Operation:
Status Affected:
[ label ] BNN n
-128 ⤠n ⤠127
if negative bit is â0â
(PC) + 2 + 2n â PC
None
Encoding:
Description:
1110 0111 nnnn nnnn
If the Negative bit is â0â, then the
program will branch.
The 2âs complement number â2nâ 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:
1
Cycles:
1(2)
Q Cycle Activity:
If Jump:
Q1
Q2
Decode
Read literal
ânâ
No
operation
No
operation
If No Jump:
Q1
Q2
Decode
Read literal
ânâ
Q3
Process
Data
No
operation
Q3
Process
Data
Q4
Write to PC
No
operation
Q4
No
operation
Example:
HERE
Before Instruction
PC
=
After Instruction
If Negative =
PC
=
If Negative =
PC
=
BNN Jump
address (HERE)
0;
address (Jump)
1;
address (HERE+2)
 2002 Microchip Technology Inc.
DS41159B-page 287
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