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problem with programming 89c2051 !

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New Member
hello ;
i made TAFE programmer ( www.ic-prog.com ) , but it doesn't work !
and also i don't know which software i should use ( 104 a , 105 , 104c ?? )
my problem is this :
when i open a hex file and program 89c2051 , after programming when it verifys the divice , it says verify faild at 000h !
and one more question , if i program both 2 lock bits , can i reprogram 89c2051 later ?
i will be happy if you help me ,
thank you .


Active Member
I had constructed TAFE programmer long back, but I never used it because after construction was complete, I figured out one major design fault which could blow up your parallel port. :shock:
The problem lies at PNP transistor Q2 whose biasing network is connected to PIN 14 of parallel port. After construction, I measured around 12V at pin 14 of parallel port which is sufficient to blow its input buffer IC. Actually, if you want to use NPN transistor as high voltage swicth operated with digital logic, a PNP transistor should be usedbetween its base and ground so that the base current of PNP transistor will be directly grounded instead of sinking into the port pin. This way, high voltage side(12V) is isolated from digital logic side.

Regarding your second question: Yes you can reprogram 89C2051 even after lock bits have been set. But you need to erase the device in order to clear the bits.
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