PIC16F722AT-ISLASHSP datasheet(177/284 Pages) MICROCHIP

177 / 284 page

 2010 Microchip Technology Inc.

DS41417A-page 177

PIC16F/LF722A/723A

18.0 PROGRAM MEMORY READ

The Flash program memory is readable during normal

operation over the full VDD range of the device. To read

data from program memory, five Special Function

Registers (SFRs) are used:

•PMCON1

•PMDATL

•PMDATH

• PMADRL

• PMADRH

The value written to the PMADRH:PMADRL register

pair determines which program memory location is

read. The read operation will be initiated by setting the

RD bit of the PMCON1 register. The program memory

Flash controller takes two instructions to complete the

read. As a consequence, after the RD bit has been set,

the next two instructions will be ignored. To avoid

conflict with program execution, it is recommended that

the two instructions following the setting of the RD bit

are NOP. When the read completes, the result is placed

in the PMDATLH:PMDATL register pair. Refer to

Example 18-1 for sample code.

EXAMPLE 18-1:

PROGRAM MEMORY READ

Note:

Code-protect does not effect the CPU

from performing a read operation on the

program memory. For more information,

refer to Section 8.2 “Code Protection”

BANKSEL PMADRL ;

MOVF

MS_PROG_ADDR, W;

MOVWF

PMADRH ;MS Byte of Program Address to read

MOVF

LS_PROG_ADDR, W;

MOVWF

PMADRL ;LS Byte of Program Address to read

BANKSEL PMCON1 ;

BSF

PMCON1, RD;Initiate Read

NOP

;Any instructions here are ignored as program

;memory is read in second cycle after BSF

BANKSEL PMDATL ;

MOVF

PMDATL, W;W = LS Byte of Program Memory Read

MOVWF

LOWPMBYTE;

MOVF

PMDATH, W;W = MS Byte of Program Memory Read

MOVWF

HIGHPMBYTE;

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