at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 47

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

Errors Report / Miscelaneous
states
Flash Busy flag
Flash Programming Sequence
Error
Power Down Mode Request
7663B–8051–03/07
The FBUSY flag indicates on-going flash write operation.
The busy flag is set by hardware, the hardware clears this flag after the end of the pro-
gramming operation.
When a wrong sequence is detected the FSE in FSTA is set.
The following events are considered as not correct activation sequence:
- The two “MOV FCON,5x and MOV FCON, Ax” were not consecutive, or the second
intruction differs from “MOV FCON Ax” (for example, an interrupt occurs during the
sequence).
- The sequence(write flash or reset column latches) occured with no data loaded in the
column latches
The FSE bit can be cleared:
- By software
- By hardware when a correct programming sequence sequence occurs.
Note: When a good sequence occurs just after an incorrect sequence, the previous error
is lost. The user software application should take care to check the FSE bit before initiat-
ing a new sequence.
In Power Down mode, the on-chip flash memory is deselected (to reduce power con-
sumption), this leads to the lost of the columns latches content.
In this case, if columns latches were previously loaded they are reseted: FLOAD bit in
FSTA register should be reseted after power down mode.
If a power down mode is requested during flash programming (FBUSY=1), all power
down sequence instructions should be ignored until the end of flash process.
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