PIC18F4420-E View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F4420-E

28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

Microchip Technology 

PIC18F2420/2520/4420/4520

CLRF

Syntax:

Operands:

Operation:

Status Affected:

Encoding:

Description:

Words:

Cycles:

Q Cycle Activity:

Q1

Decode

Clear f

CLRF f {,a}

0 ≤ f ≤ 255

a ∈ [0,1]

000h → f

1→Z

Z

0110 101a ffff ffff

Clears the contents of the specified

register.

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.

1

1

Q2

Read

register ‘f’

Q3

Process

Data

Q4

Write

register ‘f’

Example:

CLRF

Before Instruction

FLAG_REG =

After Instruction

FLAG_REG =

FLAG_REG, 1

5Ah

00h

CLRWDT

Syntax:

Operands:

Operation:

Status Affected:

Encoding:

Description:

Words:

Cycles:

Q Cycle Activity:

Q1

Decode

Clear Watchdog Timer

CLRWDT

None

000h → WDT,

000h → WDT postscaler,

1 → TO,

1 → PD

TO, PD

0000 0000 0000 0100

CLRWDT instruction resets the

Watchdog Timer. It also resets the

postscaler of the WDT. Status bits, TO

and PD, are set.

1

1

Q2

No

operation

Q3

Process

Data

Q4

No

operation

Example:

CLRWDT

Before Instruction

WDT Counter

=?

After Instruction

WDT Counter

= 00h

WDT Postscaler = 0

TO

=1

PD

=1

 2004 Microchip Technology Inc.

Preliminary

DS39631A-page 283

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