ADC readings problem

I’m having the same problem.

I have tested with this Pixhawk power module and standard 60A APM power module. Both didn’t give any current reading (A3). I’ve tested the load at 10Amp.

Is it the same with APM? Are there current readings in Mission Planner or it also stays zero?

I don’t have apm fc to test. No current readings in the mission planner even though i put the load to 10amps and 20amps.

Do you have a voltmeter/multimeter? Can you measure the real voltage on the pin?

Yes, I have. Which pin to test?

Pin 3 in the Power port (counting from the red wire side).

Here are the results:

  1. APM Power Module 5.214V
  2. Pixhawk PDB with UBEC 5.307V

I meant power port on the Navio, to measure the real value on the ADC channel for current.

I’m sorry. It is 5.229V on pin 3.

So, pin 3 (marked red on the picture) is 5.229V with the power module plugged in, right?
Could you please also measure pin 4 (marked blue on the picture)?

What was the current at the moment of the measurement?
What battery do you have?

Yes.i measured the pin as picture while the power module is on. Pin 4 is 3.8v. I’m using multistar 8ah 4s.

Current while measuring is around 1.2A.

1.2A when gimbal attached. Without gimbal around 0.7A.

Could you please also measure voltage on these pins without power module connected?

Which pins, 3 and 4? Without power module is it by using usb to power the raspi + navio?

Yes, both 3 and 4 with RPi+Navio powered over USB.

pin 3 - 0V
pin 4 - 0V

Okay, could you please do the following now with the same configuration (no PM connected, powered over USB):

  1. Run ADC example
  2. Carefully short-circuit pins 2 and 3 (using tweezers or using a df13-to-jumper-wire cable if you have one) - do you see the value of A3 changing?
  3. Repeat the the previous step for pins 2 and 4 - do you see value of A2 changing?

short circuit pin 2-3 - 0v
short circuit pin 2-4 - 0.02 - 0.04V

Oh, sorry, my bad, that wouldn’t work as there is no 5V in power port without the power module.
Please do the last test: when powered over USB consequently short-circuit pins 3 and 4 in power port to pin 1 (5V) in ADC port and check if the values change in ADC example.