PIC18LF4331T-I/SP View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18LF4331T-I/SP

28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D

Microchip Technology 

PIC18F2331/2431/4331/4431

8.3 Reading the Flash Program

Memory

The TBLRD instruction is used to retrieve data from

program memory and place it into data RAM. Table

reads from program memory are performed one byte at

a time.

TBLPTR points to a byte address in program space.

Executing a TBLRD instruction places the byte pointed

to into TABLAT. In addition, TBLPTR can be modified

automatically for the next table read operation.

The internal program memory is typically organized by

words. The Least Significant bit of the address selects

between the high and low bytes of the word. Figure 8-4

shows the interface between the internal program

memory and the TABLAT.

FIGURE 8-4:

READS FROM FLASH PROGRAM MEMORY

Program Memory

(Even Byte Address) (Odd Byte Address)

Instruction Register

(IR)

FETCH

TBLPTR = xxxxx1

TBLPTR = xxxxx0

TBLRD

TABLAT

Read Register

EXAMPLE 8-1: READING A FLASH PROGRAM MEMORY WORD

READ_WORD

MOVLW

MOVWF

MOVLW

MOVWF

MOVLW

MOVWF

CODE_ADDR_UPPER

TBLPTRU

CODE_ADDR_HIGH

TBLPTRH

CODE_ADDR_LOW

TBLPTRL

TBLRD*+

MOVF TABLAT,W

MOVWF WORD_EVEN

TBLRD*+

MOVF TABLAT,W

MOVWF WORD_ODD

; Load TBLPTR with the base

; address of the word

; read into TABLAT and increment TBLPTR

; get data

; read into TABLAT and increment TBLPTR

; get data

 2010 Microchip Technology Inc.

DS39616D-page 89

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