Rainbow Electronics T89C5115 - Manual (Page 39)

39
T89C5115
4128A–8051–04/02
Boot Process
Software Boot Process
Example Many algorithms can be used for the software boot process. Before describing them,
The description of the different flags and bytes is given below:
Boot Loader Jump Bit (BLJB):
- This bit indicates if on RESET the user wants to jump to this application at address
@0000h on FM0 or execute the boot loader at address @F800h on FM1.
- BLJB = 0 on parts delivered with bootloader programmed.
- To read or modify this bit, the APIs are used.
Boot Vector Address (SBV):
- This byte contains the MSB of the user boot loader address in FM0.
- The default value of SBV is FFh (no user boot loader in FM0).
- To read or modify this byte, the APIs are used.
Extra Byte (EB) & Boot Status Byte (BSB):
- These bytes are reserved for customer use.
- To read or modify these bytes, the APIs are used.
Figure 17. Hardware Boot Process Algorithm
RESET
BLJB == 0
?
Ha
rd
wa
re
So
ft
wa
re
Boot Loader
in FM1
Application
in FM0
bit ENBOOT in AUXR1 register
is initialized with BLJB.
ENBOOT = 0
PC = 0000h
ENBOOT = 1
PC = F800h