On 11/01/2011 11:17, Isaac Marino Bavaresco wrote:
> By your description, the circuit is probably crying "LATCHUP".
>
> Put some more protection components between the MCU pins and the base of
> the transistors.

I agree Latchup looks like the most likely culprit, but how it's=20
happening is what I thought may be a little different.
I noted Joe said he tried an opto-isolator, which should provide pretty=20
good protection on the pin. If a "direct" path, I thought it more likely=20
the power supply may be getting corrupted (i.e. if the HV and PIC=20
circuits are sharing power+ground)
If this is the case a DC to DC could be used between the two sections=20
(looks like it's all powered by the battery from the circuit posted)
Certainly "interesting" in the sense there seem to be many=20
possibilities, and it looks like a hard one to diagnose (I say this=20
judging from the time Joe has spent debugging already seems to indicate=20
something a little less "obvious")  Something to monitor/react to the RF=20
would be handy, which can trigger a scope and debugger.


--=20
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