Input impedance Type C pins

[MCRider]

Hello,

I would like to convert a trim servo signal to an analog signal using an Arduino board and feed it into a type C EMS input pin. The analog signal is generated by PWM. To select reasonable values for the filter I would like to know the input impedance of the EMS inputs. I couldn't find anything in the manual or in the forum.

Any help is welcome.

Thanks

MCRider

 

[MCRider]

No one with any idea? 

 

[dynonsupport]

Sorry for missing this while we were at Oshkosh.

When configured as a input with no pull-up, the GP pin has no specific impedance to ground. It's going through a mux and into an ADC. So it's meghoms but probably different on every unit.

The stock configuration for a position input is not no pull-up however, it is a 10K pull up to 5V. You will need to edit the sensor file to turn off this pull up if you are using this method.

 

[MCRider]

No problem. Thanks for the answer.

So I have to change "low_resistance=PULL_UP_10K" to "low_resistance=NONE" and "high_resistance=PULL_UP_10K" to "high_resistance=NONE" in the "sensor={  id=POSITION" section?

This will probably mean that the elevator trim input (which uses a potentiometer) also loses the internal pull-up? This should be easy to fix with an external pull-up...

Or is it better to create a second sensor definition with deactivated pull-up? Something like "POS (VOLTAGE)" (and limited to type C pins)?

 

[MCRider]

I just wanted to let you know that everything is working fine.

The aileron trim servo is the same thing used in RC airplanes. The signal (sort of PWM with a pulse width between 1ms and 2ms and the pulse width directly controlling the position of the servo).

To get the position into the SkyView EMS I used an Arduino Pro Mini board with a small program (around 50 lines of code). It decodes the signal and converts it into a "real" PWM signal that is filtered to output an analog voltage between 0 and 5 Volts. I created a new sensor type "POS (VOLTAGE)" without pull-up.

If someone is interested in more details just let me know.

MCRider