PIC16F720-ESLASHML datasheet(25/244 Pages) MICROCHIP

25 / 244 page

 2010 Microchip Technology Inc.

DS41430A-page 25

PIC16F/LF720/721

2.5

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

actually accesses data pointed to by the File Select

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 register and the IRP bit of

the STATUS register, as shown in Figure 2-6.

A simple program to clear RAM location 020h-02Fh

using indirect addressing is shown in Example 2-2.

EXAMPLE 2-2:

INDIRECT ADDRESSING

FIGURE 2-6:

DIRECT/INDIRECT ADDRESSING

MOVLW020h

;initialize pointer

MOVWFFSR

;to RAM

BANKISEL020h

NEXTCLRFINDF

;clear INDF register

INCFFSR

;inc pointer

BTFSSFSR,4 ;all done?

GOTONEXT

;no clear next

CONTINUE

;yes continue

Note:

For memory map detail, refer to Figures 2-3 and 2-4.

Data

Memory

Indirect Addressing

Direct Addressing

Bank Select

Location Select

RP1

RP0

From Opcode

IRP

File Select Register

Bank Select

Location Select

180h

1FFh

00h

7Fh

Bank 0

Bank 1

Bank 2

Bank 3

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