at89c5131 ATMEL Corporation, at89c5131 Datasheet - Page 44

• Manufacturer Part Number: at89c5131
• Description: 8-bit Flash Microcontroller With Full Speed Usb Device At89c5131
• Manufacturer: ATMEL Corporation

Boot Process
Software Boot Process
Example
Figure 21. Hardware Boot Process Algorithm
4136C–USB–04/05
Application
in FM0
ENBOOT = 0
PC = 0000h
Many algorithms can be used for the software boot process. Below are descriptions of
the different flags and Bytes.
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 @F400h on FM1.
- BLJB = 0 (i.e. bootloader FM1 executed after a reset) is the default Atmel factory pro-
gramming.
-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.
Bootloader
in FM1
BLJB == 0
RESET
?
ENBOOT = 1
PC = F400h
bit ENBOOT in AUXR1 Register
Is Initialized with BLJB Inverted.
Example, if BLJB=0, ENBOOT
is set (=1) during reset, thus the
bootloader is executed after the
reset.
AT89C5131
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