Boot Process
Figure 39. Bootloader process
RESET
If BLJB = 0 then ENBOOT bit (AUXR1) is set
else ENBOOT bit (AUXR1) is cleared
Yes (PSEN = 0, EA = 1, and ALE = 1 or not connected)
FCON = 00h
Hardware
Condition?
FCON = F0h
BLJB = 1
BLJB!= 0
?
ENBOOT = 0
BLJB = 0
ENBOOT = 1
F800h
yes = hardware boot conditions
FCON = 00h
?
BSB = 00h
?
PC = 0000h
USER APPLICATION
SBV = FCh
?
USER BOOT LOADER
Atmel BOOT LOADER
PC= [SBV]00h
94
AT89C51RB2/RC2
4180C–8051–12/03