PIC16LF876AT-I/ML View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16LF876AT-I/ML

28/40/44-Pin Enhanced Flash Microcontrollers

Microchip Technology 

PIC16F87X

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 reg-

ister. Any instruction using the INDF register actually

accesses the register pointed to by the File Select Reg-

ister, FSR. Reading the INDF register itself, indirectly

(FSR = ’0’) will read 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

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

A simple program to clear RAM locations 20h-2Fh

using indirect addressing is shown in Example 2-2.

EXAMPLE 2-2: INDIRECT ADDRESSING

MOVLW 0x20

MOVWF FSR

NEXT

CLRF INDF

INCF FSR,F

BTFSS FSR,4

GOTO NEXT

CONTINUE

:

;initialize pointer

;to RAM

;clear INDF register

;inc pointer

;all done?

;no clear next

;yes continue

FIGURE 2-6:

DIRECT/INDIRECT ADDRESSING

Direct Addressing

RP1:RP0 6

From Opcode 0

Indirect Addressing

IRP

7

FSR register

0

Bank Select Location Select

00

00h

01

80h

10

100h

11

180h

Bank Select

Location Select

Data

Memory(1)

7Fh

FFh

17Fh

1FFh

Bank 0 Bank 1 Bank 2 Bank 3

Note 1: For register file map detail, see Figure 2-3.

 2001 Microchip Technology Inc.

DS30292C-page 27

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