Manual

56
AT89C5131
4136A–USB–03/03
Figure 23. Low Pin-count Boot Process Algorithm
High Pin-Count Boot
Process
At the falling edge of RESET, the bit ENBOOT in AUXR1 register is initialized with the
value of Bootloader Jump Bit (BLJB).
Further at the falling edge of RESET if the following conditions (called Hardware condi-
tion) are detected:
• PSEN low
• EA high
BLJB = 1?
SBV < 3Fh?
ATMEL BOOTLOADER
APPLICATION PROGRAM
CUSTOMER BOOTLOADER
PC = [SBV]00h
Yes
No
RESET
F400h address
0000h address
Hardware
Software
P3_CF = FFh?
P1_CF = FFh?
P4_CF = FFh?
bit = = 0?
No
No
No
BSB = = 00h?
No
Yes
Yes
Yes
APPLICATION PROGRAM
No
YesYes