Are any of the analog inputs on the Swan 5vdc tolerant?

Hey-yo! I have a hardware question about the Swan and I couldn’t find an answer on the datasheet.

Q: Is the Swan 5v tolerant on ADC inputs?

More context:

The STM32 datasheet says that inputs can be 5v tolerant and gives a formula for determining max voltage, but I’m not sure what features are getting used on the board to know what values to plug in. When I make a guess at what features are getting used, it seems like I could do up to 5.22v on the inputs. :person_shrugging:

I’m wanting to do some gas sensing with a few of the MQ-family of sensors. I have a bunch on hand and would like to use what I’ve got vs. buying something new*.

The MQs use 5v to power the heater and runs that through internal resistor. In practice, it’s probably quite a bit lower then 5v. I just don’t want to burn out a pin, or worse, the entire MCU. I’d also like to avoid doing a bunch of dividers to save prototyping space. I’m planning on using 4 of the sensors and comparing them for various gasses. I’m also not sure about the impedances, so I’m not 100% sure a voltage divider will even work well.

Anyway, before I get more off into the weeds I figured I’d just ask. :slight_smile:

* I saw the Sparkfun Indoor Air Quality Sensor was used in the Air quality accelerator. That sensor uses I2C and 3.3v, so electrically it works. I’m just wanting to use the MQs.

Hi JT!

It’s on our list to update the datasheet with 5v tolerance information. These pins are 5v tolerant, and both support ADC:

  • D11 - PA7 - 5v tolerant
  • D12 - PA6 - 5v tolerant

I hope that helps.



it definitely does. Thanks!