Datasheet

50
AT89C51AC3
4383D–8051–02/08
Figure 27. Hardware Programming Procedure
Reset the Column Latches An automatic reset of the column latches is performed after a successful Flash
write sequence. User can also reset the column latches manually, for instance
to reload the column latches before writing the Flash. The following procedure is
summarized below.
• Save and disable the interrupts.
• Launch the reset by writing the data sequence 56h followed by A6h in FCON
register (only from FM1).
• Restore the interrupts.
Error Reports
Flash Programming Sequence
Errors
When a wrong sequence is detected, the SEQERR bit in FSTA register is set. Possible
wrong sequence are :
• MOV FCON, 5xh instruction not immediately followed by a MOV FCON, Ax
instruction.
• A write Flash sequence is launched while no data were loaded in the column latches
The SEQERR bit can be cleared
• By software
• By hardware when a correct programming sequence is completed
When multiple pages are written into the Flash, the user should check FSTA for errors
after each write page sequences, not only at the end of the multiple write pages.
Flash Spaces
Programming
Save and Disable IT
EA = 0
Launch Programming
FCON = 54h
FCON = A4h
End Programming
RestoreIT
FBusy
Cleared?
Clear Mode
FCON = 00h
Data Load
DPTR = 00h
ACC = Data
Exec: MOVX @DPTR, A
FCON = 0Ch
Save and Disable IT
EA = 0
End Loading
Restore IT