723T View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

723T

28/40/44-Pin Flash Microcontrollers with nanoWatt XLP Technology

Microchip Technology 

PIC16F72X/PIC16LF72X

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

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 register and the IRP bit of

the STATUS register, as shown in Figure 2-8.

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

using indirect addressing is shown in Example 2-2.

EXAMPLE 2-2: INDIRECT ADDRESSING

MOVLW

MOVWF

BANKISEL

NEXT CLRF

INCF

BTFSS

GOTO

CONTINUE

020h

FSR

020h

INDF

FSR

FSR,4

NEXT

;initialize pointer

;to RAM

;clear INDF register

;inc pointer

;all done?

;no clear next

;yes continue

FIGURE 2-8:

DIRECT/INDIRECT ADDRESSING

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

Note:

7Fh

Bank 0 Bank 1 Bank 2

For memory map detail, refer to Figures 2-4 and 2-5.

1FFh

Bank 3

© 2009 Microchip Technology Inc.

DS41341E-page 31

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