at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 63

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

Write commands
FLASH
CONFIGURATION
SECURITY
46
AT89C51RE2
The following table summarizes the memory spaces for which the write command can
be applied.
Table 28. Memory space & Select page
In case of write command to other area, nothing is done.
The bootloader returns a Write protection (‘P’) if the SECURITY do not allow any write
operation from the bootloader.
The program/data Flash memory area can be programmed by the bootloader by data
pages of up to 128bytes.
If the Flash memory security level is at least ‘2’ (FLB2:0 = ‘110’), no write operation can
be performed through the bootloader.
Table 29. Flash Write Autorisation Summary
Table 30.
The FCB configuration byte can always be written, whatever are the security levels.
The Security byte can always be written with a value that enables a protection higher
than the previous one.
If attempting to write a lower security, no action is performed and the bootloader returns
a protection error code (‘P’)
Table 31. Security Write Autorisation Summary
FLASH
SECURITY
CONFIGURATION
Write
111
110
101
011
Memory/Information Family
Command
write from
FLB2:0
Allowed
Allowed
Forbidden
Forbidden
Forbidden
111
111
Forbidden
Allowed
Allowed
Forbidden
Forbidden
Security level (HSB)
Security level (HSB)
only a higher level can be writen
110
110
need security level check
Comments/Restriction
to FLB2:0
FLB2:0
Forbidden
Allowed
Allowed
Allowed
Forbidden
101
101
Forbidden
Allowed
Allowed
Allowed
Allowed
011
011
7663B–8051–03/07