When I suggested you try "simpler" I never for a second meant that you should dive off into using interrupts. I suggested that you simply try your software in a mode where you setup each A/D in a simple single conversion on request mode instead of the repeated auto conversion mode. This mode is always simpler with respect to the internal A/D hardware and if used and seen working can point to some issue with using the auto repeat mode(s).

I just mentioned that I often (almost always) have used the on-board A/D converters in a single conversion mode. It offers a bit more flexibility at maybe some expense in terms of MCU bandwidth consumed. When I have instances where I need to support chains of conversions from multiple channels I setup an interrupt on conversion complete to grab the current result and then software trigger the next conversion.

I have not had any applications where I ever had to use synchronized channel conversions or timer hardware triggered conversions. Kind of surprising, actually, considering the number of things I have used MCU A/D converters for.

Michael Karas