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Atmel AT89C51ID2 Data Sheet - Keil

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Boot Process<br />

Figure 49. Bootloader Process<br />

Hardware<br />

Software<br />

4289A–8051–09/03<br />

PC=0000h<br />

USER APPLICATION<br />

BLJB=1<br />

ENBOOT=0<br />

RESET<br />

Hardware<br />

condition?<br />

BLJB!= 0<br />

?<br />

FCON = 00h<br />

?<br />

<strong>AT89C51ID2</strong><br />

Yes (PSEN = 0, EA = 1, and ALE =1 or not connected)<br />

FCON = 00h<br />

FCON = F0h<br />

F800h<br />

BSB = 00h<br />

?<br />

SBV = FCh<br />

?<br />

BLJB=0<br />

ENBOOT=1<br />

USER BOOT LOADER<br />

PC= [SBV]00h<br />

If BLJB=0 then ENBOOT bit (AUXR1) is set<br />

else ENBOOT bit (AUXR1) is cleared<br />

yes = hardware boot conditions<br />

<strong>Atmel</strong> BOOT LOADER<br />

125

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