Datasheet

101
4235K–8051–05/08
AT89C51RD2/ED2
24.6.5 Boot Process
Figure 24-5. Bootloader Process
RESET
Hardware
Condition?
BLJB!= 0
?
User Application
Hardware
Software
Atmel BOOT LOADERUSER BOOT LOADER
BLJB = 1
BSB = 00h
?
SBV = FCh
?
PC = 0000h
PC= [SBV]00h
BLJB = 0
If BLJB = 0 then ENBOOT Bit (AUXR1) is Set
else ENBOOT Bit (AUXR1) is Cleared
ENBOOT = 1
ENBOOT = 0
Yes (PSEN = 0, EA = 1, and ALE =1 or Not Connected)