LibrePilot Forum

General Category => General Discussion => Topic started by: balbs on March 27, 2016, 07:09:53 am

Title: Revo with Pixhawk Power module - need voltage\current factor
Post by: balbs on March 27, 2016, 07:09:53 am

Hello,

My first post here. I'm setting up a Revo and hooked up a standard Pixhawk power module so that I can get the Voltage and Current values to the Librepilot GCS. Can you tell me what voltage and current factor values should I put in?

Thanks!

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: f5soh on March 27, 2016, 11:20:28 am

Hi,

Factor values should be around:
10 for Voltage
16 for Current

To be adjusted to match measurement, also consider adjusting the "ZeroCurrent" value when idle.

https://librepilot.atlassian.net/wiki/display/LPDOC/Configure+a+Current-Voltage+sensor

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: balbs on March 28, 2016, 10:21:30 pm

Thank you!

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: carpy on March 31, 2016, 09:33:05 pm

The Pixhawk power module is 5 volts, correct?  If so, be careful as the Revo is expecting 3.3v I believe.

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: balbs on March 31, 2016, 11:45:46 pm

I'm not using the power module to power the Revo. I'm just using it to get battery voltage and current readings.

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: carpy on April 01, 2016, 04:17:22 am

I figured that.  I'm just trying to make sure you saw the following warning:

"Any sensor can be used as long as the input voltage to Revo's Sensor Port pins does not exceed 3.3V. Higher values can damage board's CPU!"

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: f5soh on April 01, 2016, 07:28:12 am

That the input voltage for ADC input pins, should be 3.3V max.

Revo can be powered up to 10V, also used for all accessories: GPS, receiver... so usually +5V

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: Mateusz on April 01, 2016, 03:16:51 pm

Here it says it provides 5.3+ V power measurements http://ardupilot.org/copter/docs/common-3dr-power-module.html#connecting-the-pm-to-a-flight-controller-board
If that is what it says, then the voltage gets scaled not to max 3.3V but to max 5.3V. That's what some voltage sensors do. Revolution ADC can accept max 3.3V levels.
So you need sensor that scales voltage to below 3.3V like AttoPilot one (I am using that one, but requires soldering).

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: f5soh on April 01, 2016, 06:40:00 pm

The APM page say only the powermodule provides +5.3V, nothing more.

APM power module / sensor fit perfectly what revo need if you check the PixHawk specs:
https://pixhawk.org/modules/pixhawk

(https://forum.librepilot.org/index.php?action=dlattach;topic=1206.0;attach=2314)

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: balbs on April 01, 2016, 06:50:06 pm

Quote from: f5soh on April 01, 2016, 06:40:00 pm

The APM page say only the powermodule provides +5.3V, nothing more.

APM power module / sensor fit perfectly what revo need if you check the PixHawk specs:
https://pixhawk.org/modules/pixhawk

(https://forum.librepilot.org/index.php?action=dlattach;topic=1206.0;attach=2314)

The only thing I have connected from the power module to the Revo are pins 6 for ground, 3 for current, and 4 for battery voltage. Am I safe? I entered the values you provided earlier and it seems to work fine. BTW, I have a separate 5V to power the Revo using one of the motor output plugs.

Title: Re: Revo with Pixhawk Power module - need voltage\current factor
Post by: f5soh on April 01, 2016, 07:27:24 pm

That fine.