at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 48

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

Reading the Flash Spaces
User
Extra Row (XAF)
Hardware Security Byte
48
AT89C51RE2
The following procedure is used to read the User space:
•
Note:
Depending of the MBO2:0 bits, the MOVC A,@A+DPTR can address a specific upper
32K bytes bank. It allows to read the 32K bytes upper On-chip flash memory from one
bank to another one.
When read from the bootloader area, the user memory shall be mapped before any read
access by setting the FMR bit of the FSTA register.
By default, when the bootloader is entered by hardware conditions, the ROM area is
mapped for MOVC A,@A+DPTR operations. It is necessary to remap the user memory
before each read access.
The following procedure is used to read the Extra Row space and is summarized in
Figure 8:
•
•
•
Figure 8. XAF Reading Procedure
The following procedure is used to read the Hardware
summarized in Figure 9:
•
•
•
Read one byte in Accumulator by executing MOVC A,@A+DPTR
Map the Extra Row space by writing 01h in FCON register.
Read one byte in Accumulator by executing MOVC A,@A+DPTR with A= 0 &
DPTR= 0000h to 007Fh.
Clear FCON to unmap the Extra Row.
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 &
DPTR= 0000h.
Clear FCON to unmap the Hardware Security Byte.
FCON is supposed to be reset when not needed.
Exec: MOVC A, @A+DPTR
DPTR= @ ( 00h up to 7Fh
FCON = 00h (FPS = 0)
XRAW Unmapping
XRAW Reading
XRAW Mapping
FCON = 01h
Data Read
ACC= 0
Security
space and is
7663B–8051–03/07