PIC16F7X Datasheet, PDF (32/174 Pages) Microchip Technology – 28/40-Pin 8-Bit CMOS FLASH Microcontrollers

PIC16F7X
3.3 Reading the FLASH Program
Memory
A program memory location may be read by writing two
bytes of the address to the PMADR and PMADRH reg-
isters and then setting control bit RD (PMCON1<0>).
Once the read control bit is set, the microcontroller will
use the next two instruction cycles to read the data. The
data is available in the PMDATA and PMDATH regis-
ters after the second NOP instruction. Therefore, it can
be read as two bytes in the following instructions. The
PMDATA and PMDATH registers will hold this value
until the next read operation.
3.4 Operation During Code Protect
FLASH program memory has its own code protect
mechanism. External Read and Write operations by
programmers are disabled if this mechanism is
enabled.
The microcontroller can read and execute instructions
out of the internal FLASH program memory, regardless
of the state of the code protect configuration bits.
EXAMPLE 3-1: FLASH PROGRAM READ
BSF
BCF
MOVF
MOVWF
MOVF
MOVWF
BSF
STATUS, RP1
STATUS, RP0
ADDRH, W
PMADRH
ADDRL, W
PMADR
STATUS, RP0
;
; Bank 2
;
; MSByte of Program Address to read
;
; LSByte of Program Address to read
; Bank 3 Required
Required BSF
Sequence NOP
NOP
PMCON1, RD
; EEPROM Read Sequence
; memory is read in the next two cycles after BSF PMCON1,RD
;
BCF
MOVF
MOVF
STATUS, RP0
PMDATA, W
PMDATH, W
; Bank 2
; W = LSByte of Program PMDATA
; W = MSByte of Program PMDATA
TABLE 3-1: REGISTERS ASSOCIATED WITH PROGRAM FLASH
Address Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on:
POR,
BOR
Value on
all other
RESETS
10Dh
PMADR Address Register Low Byte
xxxx xxxx uuuu uuuu
10Fh
PMADRH —
—
— Address Register High Byte
xxxx xxxx uuuu uuuu
10Ch
PMDATA Data Register Low Byte
xxxx xxxx uuuu uuuu
10Eh
PMDATH —
— Data Register High Byte
xxxx xxxx uuuu uuuu
18Ch
PMCON1 —⁽¹⁾
—
—
—
—
—
—
RD 1--- ---0 1--- ---0
Legend: x = unknown, u = unchanged, r = reserved, - = unimplemented read as '0'. Shaded cells are not used during FLASH access.
Note 1: This bit always reads as a ‘1’.
DS30325B-page 30
 2002 Microchip Technology Inc.