T89C51RD2-3CSCM View Datasheet(PDF) - Atmel Corporation
Part Name
Description
Manufacturer
T89C51RD2-3CSCM Datasheet PDF : 104 Pages
| |||
Functional Description
Configuration and
Manufacturer Information
The table below lists Configuration and Manufacturer byte information used by the boot-
loader. This information can be accessed through a set of API or ISP commands.
Mnemonic
Description
Default Value
BSB
Boot Status Byte
FFh
SBV
Software Boot Vector
FCh
SSB
Software Security Byte
FFh
Manufacturer Id
58h
Id1: Family code
D7h
Id2: Product Name
FCh
Id3: Product Revision
FFh
Software Security Bits (SSB)
The SSB protects any Flash access from ISP command.
The command "Program Software Security bit" can only write a higher priority level.
There are three levels of security:
• level 0: NO_SECURITY (FFh)
This is the default level.
From level 0, one can write level 1 or level 2.
• level 1: WRITE_SECURITY (10h )
For this level it is impossible to write in the Flash memory, BSB and SBV.
The Bootloader returns ’P’ on write access.
From level 1, one can write only level 2.
• level 2: RD_WR_SECURITY (00h
The level 2 forbids all read and write accesses to/from the Flash/EEPROM memory.
The Bootloader returns ’L’ on read or write access.
Only a full chip erase in parallel mode (using a programmer) or ISP command can reset
the software security bits.
From level 2, one cannot read and write anything.
Table 38. Software Security Byte Behavior
Level 0
Level 1
Level 2
Flash/EEPROM
Fuse Bit
Any access allowed
Any access allowed
Read only access allowed
Read only access allowed
Any access not allowed
Any access not allowed
BSB & SBV
SSB
Any access allowed
Any access allowed
Read only access allowed
Write level 2 allowed
Any access not allowed
Read only access allowed
64 T89C51RD2
4243G–8051–05/03
Share Link: 