Navio AUX pin and Ch7/Ch8

Is the AUX pin mapped to the First Relay Pin parameter in MP and can it be controlled with the Ch7/Ch8 switches?

I’d like to use the AUX pin to control this physical RC Relay Switch

@Al_B GPIO pins in APM on Navio\Raspberry are mapped directly, so it should work if you specify its number - AUX pin GPIO number is 12.

@mikhailavkhimenia Specify its number where? MP or directly in the code?

Does anyone know how to specify the Navio AUX pin to Ch7?


Sorry, I may have misunderstood your question. I meant that if there’s a place where you can specify a GPIO and you want to use Navio AUX pin for that then you can specify number 12.

In Mission Planner’s standard params pin numbers are hard-coded and not suitable for Navio:

But in advanced parameters you can specify the pin number directly:


I manually set the pin to 12 as you suggested, but I’m still not able to trigger the relay. Here are the parameters, please let me know I missed something else.


Has the radio calibration been successful? Is Ch7’s bar moving when you move the sticks?

What is exactly wrong? The pin doesn’t toggle at all, does it?

Hi George,

Yes, the radio has been calibrated and the Ch7’s bar moves when I move the stick as shown here.

When I posted my previous message, it was not turning the relay ON at all. After I set CAM_TRIGG_TYPE back to 0:Servo and RELAY_DEFAULT back to 0, then I was able to turn the relay ON. However, I cannot trigger it consistently as show in the video. Any suggestions? TIA!


Thanks for the video! I’ll look into the issue more closely tomorrow and will try to reproduce the problem.

Hi George,

Have you had a chance to reproduce it?

Looking at the AP_Relay code, I don’t see a reason why it would not work consistently. Is AUX pin working for anyone with the Copter-3.3.2 release?