> -----Original Message-----
>
> > was telling me there were 17 CPLDs on the JTAG bus, then the whole thing
> > quit and the 3.3v bus is shorted to ground now...)
>
> I encountered that exact same failure mode on one of my builds. Did you
> get your CPLDs from DigiKey? I wonder about their stock of CPLDs. I've
> had 2 that didn't work for me so far; the second one just won't
> enumerate on the JTAG bus.
I did get them from DigiKey - I am not 100% sure if the CPLD was bad from the
start or not, because after I first powered it up and tried to program it I
started examining the boards and found many of the pins of the flash chip were
inadequately soldered (I was too quick with the drag technique - after I found
a couple of pins not 'stuck' I pried gently under the chip to see if any pins
would visibly lift from the board and one whole end of the chip popped right
off the PCB)... the second time I tried to program the CPLD after mounting a
new flash chip I had similar results for a few minutes, followed by death,
after which I found a tiny solder bridge on the flash chip which I could only
make out with 10x magnification.
DigiKey's stock of this CPLD is all old, obviously, as is everybody's - I'm
given to understand that these parts are no longer made. It was nicely packed
with a dessicant pack and a humidity telltale card but of course that assumes
it was properly stored for years and/or recently baked, if that's the problem...
I guess the test would be to try making a batch out of freshly-baked CPLDs and
see if the failure rate changes. I'd need to get a toaster oven to try this
myself since my kitchen oven is gas (and I've already built all but one of them
anyway).
jim
