Microchip Technology AC244049 Data Sheet

DS41341E-page 189

PIC16F72X/PIC16LF72X

18.0

PROGRAM MEMORY READ

The Flash program memory is readable during normal
operation over the full V

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, causing the second instruction after the setting
the RD bit will be ignored. To avoid conflict with pro-
gram execution, it is recommended that the two instruc-
tions 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

;