Power Down Request
Reading the Flash Spaces
User
Extra Row
Hardware Security Byte
Before entering in Power Down (Set bit PD in PCON register) the user should check that
no write sequence is in progress (check BUSY=0), then check that the column latches
are reset (FLOAD=0 in FSTA register. Launch a reset column latches to clear FLOAD if
necessary.
The following procedure is used to read the User space:
• Read one byte in Accumulator by executing MOVC A,@A+DPTR with
A+DPTR=read@.
Note: FCON is supposed to be reset when not needed.
The following procedure is used to read the Extra Row space and is summarized in
Figure 28:
• Map the Extra Row space by writing 02h in FCON register.
• Read one byte in Accumulator by executing MOVC A,@A+DPTR with A = 0 and
DPTR = FF80h to FFFFh.
• Clear FCON to unmap the Extra Row.
The following procedure is used to read the Hardware Security space and is
summarized in Figure 28:
• Map the Hardware Security space by writing 04h in FCON register.
• Read the byte in Accumulator by executing MOVC A,@A+DPTR with A = 0 and
DPTR = 0000h.
Figure 28. Clear FCON to unmap the Hardware Security Byte.Reading Procedure
Flash Spaces Reading
Flash Spaces Mapping
FCON= 00000xx0b
Data Read
DPTR= Address
ACC= 0
Exec: MOVC A, @A+DPTR
Clear Mode
FCON = 00h
Flash Protection from Parallel The three lock bits in Hardware Security Byte (see "In-System Programming" section)
Programming
are programmed according to Table 17 provide different level of protection for the on-
chip code and data located in FM0 and FM1.
The only way to write this bits are the parallel mode. They are set by default to level 4
54 AT89C51CC03
4182K–CAN–05/06