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Topics - RIZ074

#1
Hi...

I've been programming some P89C51RD2HBA with Flash Magic 3.33 without problems. However have noticed that after a while, I can't get them to go into ISP mode anymore. When PSEN is set low & P89C51RD2HBA is RESET, it would just continue to execute the previously programmed code. This does not happen after 1 try, but is after a number of successful ISP programming.

Have verified the following :
P2.6 is HIGH on RESET
P2.7 is HIGH on RESET
EA is kept HIGH
PSEN is LOW
ALE is floating (not connected) - but goes HIGH on RESET.

Is there a way to overcome this problem ?