MOD54415 ADC and DAC

[dciliske]

Actually, now that you explain it that way I see the issue, and unfortunately I believe you are correct. Looking at the schematic, AGND is tied to GND, but ADVREF is left floating, so if you don't manually tie it to Vcc, you're not going to get anything. I was mistaken because I had not realized that the supply for the ADC was separate from the rest of the module (in retrospect I understand what's going on); I guess this is another step on my learning curve of hardware design.

Well, I guess you'll have to decide to either rework it and have another spin or live without :/

[khoney]

Dan,

Since that is the case, I would really recommend modifying the NANO54415 datasheet so that pin 7 is described as "ADC and DAC Power Supply and Reference Voltage - Required to Use ADC/DAC", and pin 8 is described as "ADC and DAC Power Supply and Reference Ground - Required to Use ADC/DAC". Just saying it is a voltage reference is very misleading, and the Coldfire datasheet can easily make one believe that an internal reference is available, which is not the case.

[dciliske]

I will pass that along. I agree there should be a more explicit text to that regard (especially given the fact I was convinced it wasn't for a few days).

[jediengineer]

It might help to know you have to tie it in since the factory demo uses the ADC to detect switch changes.