Rainbow Electronics AT89C5131 - Manual (Page 38)

38
AT89C5131
4136A–USB–03/03
Table 37. Software Registers
After programming the part by ISP, the BSB must be cleared (00h) in order to allow the
application to boot at 0000h.
The content of the Software Security Byte (SSB) is described in Table 38 and Table 39.
To assure code protection from a parallel access, the HSB must also be at the required
level.
Mnemonic Description Default value
SBV Software Boot Vector FCh –
HSB
Copy of the Hardware
Security Byte
1011 1000b –
BSB Boot Status Byte 0FFh –
SSB Software Security Byte FFh –
–
Copy of the Manufacturer
Code
58h Atmel
–
Copy of the Device ID #1:
Family Code
D7h
C51 X2, Electrically
Erasable
–
Copy of the Device ID #2:
Memories
F7h AT89C5131 32 Kbyte
– Size and Type FBh AT89C5131 16 Kbyte
–
Copy of the Device ID #3:
Name
EFh
AT89C5131 32 Kbyte,
revision 0
– Revision FFh
AT89C5131 16 Kbyte,
revision 0
Table 38. Software Security Byte (SSB)
7 6 5 4 3 2 1 0
- - - - - - LB1 LB0
Bit
Number
Bit
Mnemonic Description
7 -
Reserved
Do not clear this bit.
6 -
Reserved
Do not clear this bit.
5 -
Reserved
Do not clear this bit.
4 -
Reserved
Do not clear this bit.
3 -
Reserved
Do not clear this bit.
2 -
Reserved
Do not clear this bit.
1-0 LB1-0
User Memory Lock Bits
See Table 39