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yamanoorsai
05-25-2008, 07:20 AM
Hi,
I am using a JDM PIC Programmer which I made for myself using the resources from the internet. It was working well for quite a long time. Now am facing problems with programming it. Selected memory locations inside the microcontroller are not getting programmed. I could notice this since the verification of the hex code isnt correct at all locations and it is being indicated with red letters. The locations where errors are created are usually not the same and different locations aren't getting programmed on different occasions.
Can you tell me whether the problem is with the serial port of the PC or the cable or my programmer?
I have two such programmers available with me and bot are showing the same errors some way or the other.

debu
05-25-2008, 08:14 AM
@yamanoorsai: Well, this could be a problem with your microcontroller. Have you tried using a different PIC?

If the answer to that question is 'Yes', then the problem is with your JDM. Not exacty the same, but a similar problem happened with me. I had to replace the BC547s and all the zeners, for it to work correctly again.

Regards,

Debu :)

yamanoorsai
05-25-2008, 08:49 AM
I tried replacing two micro controllers. Thanks for the suggestion. I shall try replacing the components.

allbits
05-25-2008, 12:40 PM
Yes, one of the problem i have faced with JDM based ones. JDM is not very stable always, if you have the option, use an externally powered programmer.

In your case, mostly, its not because of the PIC, it has to be something to do with your programmer.

1) Check your RS232 levels.
2) Change the transistors, as debu said.
3) I assume you are using winpic (the red letter thing), there is an option for slow mode, to check timing errors - try and see if it is a timing error.

Once, it happened to me with feng 3 - the programmer would never work. everything was fine, so i made another one, this time i used a smaller LED (the other one was a 5mm red) , and there it worked. !! By this, I am NOT asking you to change the LED and see, I am just telling you the point that JDM based ones need good RS232 levels, and a good and a neat board and assembly. I have used FENG for quite some time, without much of problems, but it could be irritating sometimes, when it simply wouldn't work for no reason whatsoever.

good luck!

yamanoorsai
05-25-2008, 12:45 PM
Before replacing the components, I decided to test it on another system and I tried using it in my friend's PC after reading debu's reply. The programmer has no problems. It is working perfect. What could be the problem with my serial port?

Can you help me check the RS 232 levels? How am I supposed to do that?

docel
05-26-2008, 02:01 AM
JDMs have a Ghost that periodically appear and stay put...!
You have some capacitors on the board. Change them, especially the electrolytics.
And...never use a multimeter with the JDM ON and connected to the Port :!:

BTW, forget the Homebrew JDMs and buy a decent programmer.

a7400
05-26-2008, 10:16 AM
newer PCs have serial ports which work on -5 to +5V... they dont provide the necessay high voltage level to erase the PIC or put it in programming mode...
so u may want to chk the voltage levels...

yamanoorsai
05-26-2008, 03:28 PM
But the same system programmed the controller previously. Now, the programmer is working good with another system. As of now, I have decided to check up with what docel and debu have suggested. Thanks a lot. I shall come back as soon as I rectify the problem.