PIC16F636T-I/SL(2005) View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16F636T-I/SL
(Rev.:2005)

8/14-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology

Microchip Technology 

PIC12F635/PIC16F636/639

2.4 Indirect Addressing, INDF and

FSR Registers

The INDF register is not a physical register. Addressing

the INDF register will cause indirect addressing.

Indirect addressing is possible by using the INDF

register. Any instruction using the INDF register

actually accesses data pointed to by the File Select

Register (FSR). Reading INDF itself indirectly will

produce 00h. Writing to the INDF register indirectly

results in a no operation (although Status bits may be

affected). An effective 9-bit address is obtained by

concatenating the 8-bit FSR and the IRP bit

(STATUS<7>), as shown in Figure 2-6.

A simple program to clear RAM location 20h-2Fh using

indirect addressing is shown in Example 2-1.

EXAMPLE 2-1: INDIRECT ADDRESSING

MOVLW

MOVWF

NEXT

CLRF

INCF

BTFSS

GOTO

CONTINUE

0x20

FSR

INDF

FSR

FSR,4

NEXT

;initialize pointer

;to RAM

;clear INDF register

;INC POINTER

;all done?

;no clear next

;yes continue

FIGURE 2-6:

DIRECT/INDIRECT ADDRESSING PIC12F635/PIC16F636/639

Direct Addressing

RP1 RP0 6

From Opcode

0

Indirect Addressing

IRP

7

File Select Register

0

Bank Select

Location Select

Bank Select

00

01

10

11

00h

180h

Location Select

Data

Memory

7Fh

Bank 0

Bank 1

Bank 2

Note: For memory map detail, see Figure 2-2.

Bank 3

1FFh

© 2005 Microchip Technology Inc.

Preliminary

DS41232B-page 27

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