Datasheet

Table Of Contents
© 2009 Microchip Technology Inc. DS39637D-page 109
PIC18F2480/2580/4480/4580
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 mem-
ory 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
followed. See Section 25.0 “Special Features of the
CPU” for more detail.
7.6 Flash Program Operation During
Code Protection
See Section 25.5 “Program Verification and 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)
DECFSZ COUNTER1
BRA WRITE_BUFFER_BACK
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
Reset
Values
on Page:
TBLPTRU —bit21
(3)
Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) 55
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>) 55
TBLPTRL Program Memory Table Pointer High Byte (TBLPTR<7:0>) 55
TABLAT Program Memory Table Latch 55
INTCON GIE/GIEH PEIE/GIEL
TMR0IE INTE RBIE TMR0IF INTF RBIF 55
EECON2 EEPROM Control Register 2 (not a physical register) 57
EECON1 EEPGD CFGS
FREE WRERR WREN WR RD 57
IPR2 OSCFIP
CMIP
(2)
EEIP BCLIP HLVDIP TMR3IP ECCP1IP
(1)
57
PIR2 OSCFIF
CMIF
(2)
EEIF BCLIF HLVDIF TMR3IF ECCP1IF
(1)
58
PIE2 OSCFIE CMIE
(2)
EEIE BCLIE HLVDIE TMR3IE ECCP1IE
(1)
58
Legend: — = unimplemented, read as ‘0. Shaded cells are not used during Flash/EEPROM access.
Note 1: These bits are available in PIC18F4X80 devices only.
2: These bits are available in PIC18F4X80 devices and reserved in PIC18F2X80 devices.
3: This bit is available only in Test mode and Serial Programming mode.