Cannot detect target chip

[physiks]

I am now using a PIC18F8620 and not the low voltage type(LF). The ICD is not able to detect my target chip or it returns a message stating "unknown PIC12/16". Has anyone experienced this?
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Eric

[physiks]

OK. Here we go again. For some reason, when I lower the voltage from 5V to something less than 4.7V it will work fine. I'm not sure I understand this. Any ideas? Anyone?
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Eric

[wulffert]

All

I have had the same headache with the U40 , but I found a solution . It may not work for all, but it is the only one for me that worked. I have 2 platforms, one is a 18F252, the other a 18F442. The U40 wouldn't see the target chip, even though I had followed CCS's rules to the letter (dedicated B6, B7, only 47K on MCLR, short wires). Keep in mind I have had good results with the old ICD-S and ICD-U (I would have kept the ICD-U but I fried that, thats another story LOL ) on the same designs. What worked was this, open up the case and put the jumper in, this will get 5V from the target to power the ICD. I put 2.2K term resistors on B6 and B7 and tied them to VDD (5V). Now the ICD-U40 works perfect . Won't work for 3V systems (you can make your own interface), so your mileage may vary. So why does this work? Probably noise on the 5V from the USB getting onto the ICD, and some additional noise on B6, B7. The U40 is a lot faster than its predecessors, maybe they could allow for a wait state when toggling the B6, B7 so it runs a bit slower.... just an idea.

Good luck

Mark

[Saratoga]

Put the internal jumper of ICD unit
this work fine.
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To Pic Or No To Pic

[physiks]

Thanks for your suggestions. I will try all of them. I just would like to understand the behavior.
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Eric