PIC18F87K22 Datasheet, PDF (118/548 Pages) Microchip Technology – 64/80-Pin, High-Performance, 1-Mbit Enhanced Flash Microcontrollers with 12-Bit A/D and nanoWatt XLP Technology

PIC18F87K22 FAMILY
EXAMPLE 7-3: WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
PROGRAM_MEMORY
BSF
BCF
BSF
BCF
MOVLW
Required MOVWF
Sequence MOVLW
MOVWF
BSF
BSF
BCF
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
INTCON, GIE
0x55
EECON2
0xAA
EECON2
EECON1, WR
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)
; re-enable interrupts
; disable write to memory
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
followed. See Section 28.0 “Special Features of the
CPU” for more detail.
7.6 Flash Program Operation During
Code Protection
See Section 28.6 “Program Verification and Code
Protection” for details on code protection of Flash
program memory.
TABLE 7-2: REGISTERS ASSOCIATED WITH PROGRAM FLASH 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
IPR6
—
—
—
EEIP
—
CMP3IP CMP2IP CMP1IP
PIR6
—
—
—
EEIF
—
CMP3IF CMP2IF CMP1IF
PIE6
—
—
—
EEIE
—
CMP3IE CMP2IE CMP1IE
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.
DS39960B-page 118
Preliminary
 2010 Microchip Technology Inc.