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Sudden problem with pic16f628a

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fs789

New Member
hellow
i am using jdm programmer for pic16f628a and was working good until yesterday.
now when trying to program the pic16f628 with ICPROG , it gives ERROR MESSAGE. but when trying to program the pic16f84a no ERRORS OCCUR!!!!!!!
HOW CAN I KNOW IF PIC16F628A IS DAMAGED OR NOT???
PLEASE HELP ME
 

Pommie

Well-Known Member
Most Helpful Member
If you have programmed it to use the internal oscillator and MCLR off then you will need a better programmer to blank it. There can also be problems if you turn on the Timer1 oscillator as this uses the programming pins.

Mike.
 

colin55

Well-Known Member
I have had problems with JDM and ICPROG and '628A.
It seems to be a timing problem.
Take pin 10 to 0v via 10k
Increase Vpp via an extra signal diode in series with 8v2 zener.
 

fs789

New Member
I have had problems with JDM and ICPROG and '628A.
It seems to be a timing problem.
Take pin 10 to 0v via 10k
Increase Vpp via an extra signal diode in series with 8v2 zener.
please explain this sentence::Increase Vpp via an extra signal diode in series with 8v2 zener??? i dont understand this!!!
iI WAS USING THIS PROGRAMMER CIRCUIT FOR PIC16F628A AND WAS SUCCESSFUL
BUT SUDDENLY GAVE ERRORS AND DIDNOT PROGRAM!!!!!!!!!
http://img196.imageshack.us/img196/1046/partscp7.jpg
 
Last edited:

colin55

Well-Known Member
Check Vpp it must be above 13.5v Increase it by adding a diode in series with the zener that determines Vpp.
 

fs789

New Member
check vpp it must be above 13.5v increase it by adding a diode in series with the zener that determines vpp.
in order to measure vpp, on which pin of the pic i must put the voltmeter???
Also,
the pic was programmable successfully , but suddenly had problems.
Do you think the pic is now damaged???
In addition,i tryed to program pic16f84a, and was successful, but pic16f628a didnot!!!!!!!!!!!!!!!!!!!!!
Please help me
 

Nigel Goodwin

Super Moderator
Most Helpful Member
As already suggested, the JDM is a crappy programer, and if you've accidently set the PIC to use the internal oscillator then you're unable to access it any more with a JDM.
 

colin55

Well-Known Member
The PIC '628A is very temperamental with JDM programmer. Sometimes, just putting your fingers on the programming voltages during programming will get the chip programmed again.
Out of a batch of chips, some will play up and others will program perfectly.
Try a 22n between pins 5 and 18 and make sure Vpp is above 13.5v
 
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