PIC18F2331/2431/4331/4431
EXAMPLE 8-3:
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
PROGRAM_MEMORY
BCF
INTCON, GIE
55h
EECON2
0AAh
EECON2
; disable interrupts
; required sequence
; write 55h
MOVLW
MOVWF
MOVLW
MOVWF
BSF
; write 0AAh
; start program (CPU stall)
EECON1, WR
NOP
BSF
INTCON, GIE
; re-enable interrupts
; loop until done
DECFSZ COUNTER_HI
GOTO
BCF
PROGRAM_LOOP
EECON1, WREN
; disable write to memory
reprogrammed if needed. The WRERR bit is set when
8.5.2
WRITE VERIFY
a write operation is interrupted by a MCLR Reset, or a
WDT Time-out Reset during normal operation. In these
situations, users can check the WRERR bit and rewrite
the location.
Depending on the application, good programming
practice may dictate that the value written to the
memory should be verified against the original value.
This should be used in applications where excessive
writes can stress bits near the specification limit.
8.6
Flash Program Operation During
Code Protection
8.5.3
UNEXPECTED TERMINATION OF
WRITE OPERATION
See Section 23.5 “Program Verification and Code
Protection” for details on code protection of Flash
program memory.
If a write is terminated by an unplanned event, such as
loss of power or an unexpected Reset, the memory
location just programmed should be verified and
TABLE 8-2:
Name
REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY
Reset
Values
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
on Page:
TBLPTRU
—
—
bit 21(1) Program Memory Table Pointer Upper Byte (TBLPTR<20:16>)
54
54
54
54
54
56
56
57
57
57
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>)
TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>)
TABLAT Program Memory Table Latch
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE
RBIE
TMR0IF
INT0IF
RBIF
EECON2 EEPROM Control Register 2 (not a physical register)
EECON1 EEPGD
CFGS
—
—
—
—
—
FREE
EEIP
EEIF
EEIE
WRERR
WREN
LVDIP
LVDIF
LVDIE
WR
—
RD
IPR2
PIR2
PIE2
OSCFIP
OSCFIF
OSCFIE
—
—
—
CCP2IP
CCP2IF
CCP2IE
—
—
—
—
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
DS39616D-page 94
2010 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
