Rainbow Electronics AT89C5132 - Manual (Page 23)

23
AT8xC5132
4173A–8051–08/02
Hardware Bytes Table 21. HSB Byte – Hardware Security Byte
Reset Value = XXUU UXXX, UUUU UUUU after an hardware full chip erase.
Notes: 1. X2B initializes the X2 bit in CKCON during the reset phase.
2. Using the AT89C5132 (Flash Version) the system can boot either in standard or X2
mode depending on the X2B value. Using AT83C5132 (ROM Version) the system
always boots in standard mode. X2B bit can be changed to X2 mode later by
software.
3. Bits 0 to 3 (MSN) can only be programmed by hardware mode.
Table 22. SBV Byte – Software Boot Vector
Reset Value = XXXX XXXX, UUUU UUUU after an hardware full chip erase.
Table 23. SSB Byte – Software Security Byte
Reset Value = XXXX XXXX, UUUU UUUU after an hardware full chip erase.
7 6 5 4 3 2 1 0
X2B BLJB - - - LB2 LB1 LB0
Bit
Number
Bit
Mnemonic Description
7 X2B (1)(2)
X2 Bit
Program this bit to start in X2 mode.
Unprogram (erase) this bit to start in standard mode.
6 BLJB
Boot Loader Jump Bit
Program this bit to execute the bootloader at address F000h on next reset.
Unprogram (erase) this bit to execute user’s application at address 0000h on
next reset.
5 - 4 -
Reserved
The values read from these Bits are always unprogrammed. Do not program
these Bits.
3
Reserved
The values read from this bit is always unprogrammed. Do not program this bit.
2 - 0 (3) LB2:0
Hardware Lock Bits
Refer to Table 21 for Bits description.
7 6 5 4 3 2 1 0
ADD15 ADD14 ADD13 ADD12 ADD11 ADD10 ADD9 ADD8
Bit
Number
Bit
Mnemonic Description
7 - 0 ADD15:8
MSB of the user’s bootloader 16-bit address location
Refer to the AT8xC5132 datasheet for usage information (bootloader
dependent).
7 6 5 4 3 2 1 0
SSB7 SSB6 SSB5 SSB4 SSB3 SSB2 SSB1 SSB0
Bit
Number
Bit
Mnemonic Description
7 - 0 SSB7:0
Software Security Byte Data
Refer to the AT8xC5132 datasheet for usage information (bootloader
dependent).