PixRacer Power Module

PX4 Autopilot
1

Hello,

I’ve wanted to add current and voltage sense capability to my PixRacer, but I’m confused as to what voltage the sense pins expect. Most of the APM modules I’ve found output 0-5v ADC. However, the Pixracer board specs (https://pixhawk.org/modules/pixracer) list it’s current and sense pins as limited to 3.3v.

What power module should I use for the racer that will output its ADC in the correct 0-3.3v range? Is there a way to change the ADC output of power modules without using a voltage divider circuit? Like can I reflash the firmware or something?

Currently, I’m using this (Amazon.com) but without the current or voltage sense pins connected.

Thank you for any tips/guidance provided. This is my first drone I’ve built and would hate to accidentally fry the flight controller.

2

This is a good one
https://store.mrobotics.io/product-p/mro-acsp7v10-mr.htm

3

Thank you CarlOlsson, that is quite a nice one. Its a bit outside my budget though. :weary: Have you used it in the past? Since if it really does provide much better battery estimates then it could be worth it.

I have one additional question about the ADC output of the apm modules in general. Do they just output a dc value proportional to measured voltage and current? As in, would the module I already have still work as long as I don’t draw more than like 40 amps through it and don’t hook it up to a 6s battery?

Thank you!
~Achillean

4

Battery estimation is not only related to ADC accuracy, but also the battery gas gauge driver runs inside flight controller as well.

Ideally a dedicated gas gauge IC should be presented to do the thing, however as per current software implementation you can not expect too much about battery estimation accuracy anyway.