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JDM programmer

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aruna1

Member
can someone explain me what is the theory behind JDM programmer? and how it differ from other programmers?
thank you
 

Triode

Active Member
Yes, I had one before I got one of Bills Pickit 2 style programmers. While I was using the JDM I thought pic programming was insanely complicated because programming seemed to fail or work for all kinds of reasons. Eventually I realized that it was figity and would sometimes fail for no real reason at all.
 

colin55

Well-Known Member
Sometimes the JDM programmer "locks up" a PIC chip such as 16F628 and it cannot be programmed again.
You need to re-program it on a different type of programmer to be able to re-program it.

That's the only major fault, I have found.
 

House0Fwax

Member
Sometimes the JDM programmer "locks up" a PIC chip such as 16F628 and it cannot be programmed again.
I had the same thing with a Velleman K8048 just yesterday. Though there are ways around it. I.e two bits of wire, a switch and some hot glue.
 

colin55

Well-Known Member
Let us know what you did (exactly, concisely and completely) so it can be posted for all those other JDM users.
 

House0Fwax

Member
Let us know what you did (exactly, concisely and completely) so it can be posted for all those other JDM users.
I don't know if the Velleman classes as a JDM programmer, but here goes;

I added a wire from both ends of D7 on the circuit board to a switch.
By shorting out 'D7' BEFORE putting the K8048 into program mode allows one to erase the 16F628 ( in my case ).

I learned this trick from reading about people whom had problems with the OSCAL value of the 16F675. ( Like me )

I supply the link for people who want to know where 'D7' is.
http://www.electro-tech-online.com/custompdfs/2009/09/illustrated_assembly_manual_k8048_rev4.pdf

I don't guarantee this for everyone, well, you know how skittish these waffy programmers are.
 

colin55

Well-Known Member
What software do you use with this programmer?

Vpp is not generated from the com port and so the programmer may not be
strictly called a JDM programmer. But it may use the same software as JDM.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Sometimes the JDM programmer "locks up" a PIC chip such as 16F628 and it cannot be programmed again.
You need to re-program it on a different type of programmer to be able to re-program it.
It's not 'locked up', it's a limitation of the JDM as it doesn't switch Vdd.

If you set the 16F628 to use it's internal oscilaltor you can't stop it running - and if the oscillator is running, you can't enter programming mode.

The technique is to stop the PIC running by turning Vdd OFF, then turn it back ON, and very rapidly set MCLR to Vpp.
 
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