Pixhawk mini relay output

Sorry if I’m reinventing the wheel but most posts are on the full Pixhawk and not the mini, the mini does not have dedicated aux ports. I have a relay board isolated by mosfets on the input. I need to allocate a channel, 7 , on\off provide a +5v on the signal wire to activate the relay
Please help, I’m using a jumper R8 .

Can this be achieved using a rx output or Pixhawk mini ?

Many thanks

Chaps any news please? Some guru must be able to alleviate my madness at trying to make this work ??

You could use a PWM switch.

Dave I’ve ordered one but I was really wanting to make life a bit easier and instead of adding even more weight?

Hey Jim-So the mini should be like the Pixracer and all the outputs are “Aux outputs” as it doesn’t have an IOMCU. Set BRD_PWM_COUNT to 4 and pins 55 and 56 would be available as GPIO for relays. Not sure about Vout though, think it’s at 3.3V.

Dave I don’t think they pins are available on the mini. Photo attached . I’m using a hex and a gimbal so all ports (8), pwm, are used


I think you are out of luck then for an output on the FC then. Rx output as you suggested.

Dave can I use a pwm channel on the RX such as 3 if I’m using S-Bus channel 3 for throttle on the Pixhawk ?


No. What Rx do you have? For example on a Frsky X8R you can assign the 8 PWM output pins as channels 9-16 and use them as such while using 1-8 on Sbus.

I have a jumper R8 which is 8ch pwm and 16 ch S-Bus


If you can configure the 8 PWM outputs as 9-16 like you can on Frsky Rc then it would work.

Purchased one of these but when I connect to a pwm output on my receiver it does not work ,
Any idea

MOS Trigger Switch Driver Module FET PWM Regulator High Power

No, not familiar with that unit. The one I have used simply closes a contact with a PWM input >1800us. Found this on Amazon:


That’s the one I have but the pwm signal input does nothing. All I need is the one you have, close or open a contact above a certain us level


I think I got it from Hobbyking but see they are backordered. I see the same one on eBay “Turnigy PWM switch” but the price is double what HK charges.

Can you put a small servo on your receiver and make sure your setup is working?


I don’t have a servo but I’ve tried a a flytron led and it switches on and off fine . Looking at the pdb of the so called switch there is no detector CircuitsElectronics to ‘listen’ for the pwm pulses but I may be mistaken

well at least you know the rx output is working. i am really good at releasing magic smoke so could be a bad idea… but it just appears to be using PWM at a high enough duty cycle to trigger relay. so it’s really just looking for a dc voltage from 3.3 to 20v to trigger relay. they just happen to add PWM to the feature list since you can technically get, what ~4v at 80% duty cycle if it’s starting at 5v. again, a guess.

first i would see if you can take whatever channel you are using and take the mix up to 2000, or as high as it will go when high, to see if that makes it trigger.


I will try that , it works at 5v trigger, it’s a shame there is no way to get the pix or the rx to output 5v on a switch . Seems a logical trigger not to be available when you consider the servoX functions available