PIC16F1826-E/SO View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16F1826-E/SO

18/20/28-Pin Flash Microcontrollers with nanoWatt XLP Technology

Microchip Technology 

3.1.1

READING PROGRAM MEMORY AS

DATA

There are two methods of accessing constants in pro-

gram memory. The first method is to use tables of

RETLW instructions. The second method is to set an

FSR to point to the program memory.

3.1.1.1 RETLW Instruction

The RETLW instruction can be used to provide access

to tables of constants. The recommended way to create

such a table is shown in Example 3-1.

EXAMPLE 3-1:

constants

brw

retlw DATA0

retlw DATA1

retlw DATA2

retlw DATA3

RETLW INSTRUCTION

;Add Index in W to

;program counter to

;select data

;Index0 data

;Index1 data

my_function

;… LOTS OF CODE…

movlw

DATA_INDEX

call constants

;… THE CONSTANT IS IN W

The BRW instruction makes this type of table very sim-

ple to implement. If your code must remain portable

with previous generations of microcontrollers, then the

BRW instruction is not available so the older table read

method must be used.

PIC16F/LF1826/27

 2010 Microchip Technology Inc.

Preliminary

DS41391C-page 21

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