
2010-2012 Microchip Technology Inc.
DS39977F-page 137
PIC18F66K80 FAMILY
EXAMPLE 7-3:
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
7.5.2
WRITE VERIFY
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.
7.5.3
UNEXPECTED TERMINATION OF
WRITE OPERATION
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 repro-
grammed if needed. If the write operation is interrupted
by a MCLR Reset or a WDT Time-out Reset during
normal operation, the user can check the WRERR bit
and rewrite the location(s) as needed.
7.5.4
PROTECTION AGAINST
SPURIOUS WRITES
To protect against spurious writes to Flash program
memory, the write initiate sequence must also be
for more detail.
7.6
Flash Program Operation During
Code Protection
for details on code protection of Flash
program memory.
TABLE 7-2:
REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY
PROGRAM_MEMORY
BSF
EECON1, EEPGD
; point to Flash program memory
BCF
EECON1, CFGS
; access Flash program memory
BSF
EECON1, WREN
; enable write to memory
BCF
INTCON, GIE
; disable interrupts
MOVLW
55h
Required
MOVWF
EECON2
; write 55h
Sequence
MOVLW
0AAh
MOVWF
EECON2
; write 0AAh
BSF
EECON1, WR
; start program (CPU stall)
BSF
INTCON, GIE
; re-enable interrupts
BCF
EECON1, WREN
; disable write to memory
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TBLPTRU
—
—bit 21(1) Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) 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
WRERR
WREN
WR
RD
IPR4
TMR4IP
EEIP
CMP2IP
CMP1IP
—
CCP5IP
CCP4IP
CCP3IP
PIR4
TMR4IF
EEIF
CMP2IF
CMP1IF
—
CCP5IF
CCP4IF
CCP3IF
PIE4
TMR4IE
EEIE
CMP2IE
CMP1IE
—
CCP5IE
CCP4IE
CCP3IE
Legend:
— = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
Note 1:
Bit 21 of the TBLPTRU allows access to the device Configuration bits.