PIC18F23K20 Datasheet, PDF (97/420 Pages) Microchip Technology – 28/40/44-Pin Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC18F2XK20/4XK20
EXAMPLE 6-3:
PROGRAM_MEMORY
Required
Sequence
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
DECFSZ COUNTER
; loop until holding registers are full
BRA
WRITE_WORD_TO_HREGS
BSF
BCF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
DCFSZ
BRA
BSF
BCF
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
COUNTER2
WRITE_BYTE_TO_HREGS
INTCON, GIE
EECON1, WREN
; point to Flash program memory
; access Flash program memory
; enable write to memory
; disable interrupts
; write 55h
; write 0AAh
; start program (CPU stall)
; repeat for remaining write blocks
;
; re-enable interrupts
; disable write to memory
6.5.2 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.
6.5.3
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
reprogrammed if needed. If the write operation is
interrupted by a MCLR Reset or a WDT Time-out Reset
during normal operation, the WRERR bit will be set
which the user can check to decide whether a rewrite
of the location(s) is needed.
6.5.4
PROTECTION AGAINST
SPURIOUS WRITES
To protect against spurious writes to Flash program
memory, the write initiate sequence must also be
followed. See Section 23.0 “Special Features of the
CPU” for more detail.
6.6 Flash Program Operation During
Code Protection
See Section 23.3 “Program Verification and Code
Protection” for details on code protection of Flash
program memory.
TABLE 6-3: REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY
Name
Bit 7
Bit 6 Bit 5 Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values on
page
TBLPTRU
—
—
bit 21 Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) 57
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>)
57
TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>)
57
TABLAT Program Memory Table Latch
57
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE
RBIE TMR0IF INT0IF
RBIF
57
EECON2 EEPROM Control Register 2 (not a physical register)
59
EECON1 EEPGD CFGS
—
FREE WRERR WREN
WR
RD
59
IPR2
OSCFIP C1IP C2IP EEIP
BCLIP HLVDIP TMR3IP CCP2IP
60
PIR2
OSCFIF C1IF C2IF EEIF
BCLIF HLVDIF TMR3IF CCP2IF
60
PIE2
OSCFIE C1IE C2IE EEIE
BCLIE HLVDIE TMR3IE CCP2IE
60
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
© 2007 Microchip Technology Inc.
Advance Information
DS41303B-page 95