PIC18F258-I/SP View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F258-I/SP

28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

Microchip Technology 

PIC18FXX8

BTFSC

Bit Test File, Skip if Clear

Syntax:

Operands:

Operation:

Status Affected:

Encoding:

Description:

[ label ] BTFSC f,b[,a]

0 ≤ f ≤ 255

0≤b≤7

a ∈ [0,1]

skip if (f<b>) = 0

None

1011 bbba ffff ffff

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, overriding the BSR

value. If ‘a’ = 1, then the bank will be

selected as per the BSR value (default).

Words:

Cycles:

1

1(2)

Note:

3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1

Q2

Q3

Decode

Read

register ‘f’

Process

Data

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

FALSE

TRUE

Before Instruction

PC

=

After Instruction

If FLAG<1> =

PC

=

If FLAG<1> =

PC

=

BTFSC

:

:

FLAG, 1

address (HERE)

0;

address (TRUE)

1;

address (FALSE)

BTFSS

Bit Test File, Skip if Set

Syntax:

Operands:

Operation:

Status Affected:

Encoding:

Description:

[ label ] BTFSS f,b[,a]

0 ≤ f ≤ 255

0≤b≤7

a ∈ [0,1]

skip if (f<b>) = 1

None

1010 bbba ffff ffff

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 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, overriding the BSR

value. If ‘a’ = 1, then the bank will be

selected as per the BSR value (default).

Words:

Cycles:

1

1(2)

Note:

3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1

Q2

Q3

Decode

Read

register ‘f’

Process

Data

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

FALSE

TRUE

Before Instruction

PC

=

After Instruction

If FLAG<1> =

PC

=

If FLAG<1> =

PC

=

BTFSS

:

:

FLAG, 1

address (HERE)

0;

address (FALSE)

1;

address (TRUE)

DS41159E-page 294

© 2006 Microchip Technology Inc.

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