Datasheet
PIC16F7X
DS30325B-page 30 2002 Microchip Technology Inc.
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
TABLE 3-1: REGISTERS ASSOCIATED WITH PROGRAM FLASH
BSF STATUS, RP1 ;
BCF STATUS, RP0 ; Bank 2
MOVF ADDRH, W ;
MOVWF PMADRH ; MSByte of Program Address to read
MOVF ADDRL, W ;
MOVWF PMADR ; LSByte of Program Address to read
BSF STATUS, RP0 ; Bank 3 Required
Required BSF PMCON1, RD ; EEPROM Read Sequence
Sequence NOP ; memory is read in the next two cycles after BSF PMCON1,RD
NOP ;
BCF STATUS, RP0 ; Bank 2
MOVF PMDATA, W ; W = LSByte of Program PMDATA
MOVF PMDATH, W ; W = MSByte of Program PMDATA
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’.