ADC Failure Modes

[Don_Kirby]

Don, I looked at the datasheets, as well as poking around the net, and I can't find any information regarding the failure modes of the ADC subsystem in the Mega32. I'm experiencing a lack of ADC dynamic range on all ADC channels today, and none of the external hardware has changed. It's acting as if I've lost 2 or 3 bits of resolution.

It's not impossible that the device suffered an ESD event, as it's just running on a breadboard. This unit is my long term test bed as well, so it's seen it's share of abuse.

I have yet to run any hardware tests except checking for correct voltages at the input. I've also ruled out software issues.

Have you seen this before?


-Don

[dkinzer]

I haven't seen the symptoms that you describe nor do I have specific information about ADC failure modes. If you've lost dynamic range that would suggest loss of high order bits. Losing low order bits would cause a loss of resolution.

Are you using GetADC() or are you manipulating the registers directly?

The quickest way to determine if there is a internal problem in the device is by substitution. I'd be happy to send you a new ZX-40/ZX-40a for you to try.

[Don_Kirby]

I'm using GetADC, but now that you mention it, I'll try setting the registers and see what the result is. If the chip is in fact faulty, the result should be exactly tje same I would imagine.

Thanks for the replacement offer. I'd like to hold on to this one, though I'll order a new one to replace it today.

-Don