Phillip Coiner wrote:
> CH1=VPP
> CH2=PGD
> CH3=PGC
> CH4=VDD

The rise and fall times look to be within range.  Everything looks OK for 3V
operation.  The edges all look fast enough and the data line is well settled
by the falling edge of the clock line.

>> The command was pic_prog -VDD 3 -HEX t
>> (If I use -VDD 5 the device won't talk at all.)

So that means it can communicate at 3V, but of course won't program
correctly since it can't do a bulk erase.

This is smelling more and more like a crosstalk problem.  Have you tried
putting 47pF or so caps on PGC and PGD on your board as I suggested several
messages ago?

> What should I try/measure next?

Try the things I suggested to address a crosstalk problem and see what that
does.  If that doesn't fix it I'm out of ideas.  All I can suggest then is
to send the unit back for a refund, or send me one of your boards and let me
look into it on my bench.


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