No RX input at all ...

Hi guys,

am I stupid or what's wrong? Building up the APM was easy, all sensors and outputs work fine. But why I cannot read a single input from the receiver? Tried >10 different firmwares and tested 3 different receivers with the APM -> test -> pwm, no valid input on all 8 input channels. APM is V1.4, it is connected with USB and has a BEC on Output 3. MUX-LED is always yellow and PPM-LED pulses all the time. The readings are always 1200 in each and every case.

Anyone could help? I cannot believe that the board is defect when all other things are perfect. Readed dozens of threads and wasted hours for debugging. :(

Best regards, Thomas

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  • Yes Chris, right on both counts; power is through ESC on channel 3 and the lack of input resulted from the calibration (but also checked through calibrating in terminal and checking the input feed in terminal also). I sent a mail to Udrones and we'll see what they say. Just unfortunate that I will have to send the board from Italy to Mexico and get a new one back again, I really can't wait to get my bird in the air and Italian customs tends to takes it's time.

  • This almost sounds like a bad hair day:-). If all your hardware is good then there is only the programming to educate.

    There is no Firmware as many do not have a business here yet.

    If your problem is a receiver channel to the APM there are those that can help.


  • Anyone another idea? Is there a way to proof that the 328 firmware needs a reflash before I buy the hardware for that?

  • Is your Rx bound to your Tx?  This seems like one of the first steps of troubleshooting that you didn't mention if you did.  Make sure first that with BEC connected to Rx and a servo connected that the Rx works.  You can keep the BEC connected to Rx if you want, the power rails on the APM are shared, same as how Rx power rails work (wired in parallel basically... all connected)  So powering the Rx with the BEC will power the APM as well.  Make sure your Rx works then try again on the APM

  • Developer

    Are your servo leads on upside down - seriously.  Sounds like the most likely explanation.  Next most likely is that the 328 firmware is corrupt and needs reflashed.

  • Moderator

    Try providing BEC/+5v on the lower two pins of output#1? Standard servo order, with control channel on the top, ground on the bottom? See if your rx is getting power [does your model have an LED power indicator?] rx is not powered from USB, and I know you mentioned a BEC on Output#3, but I have never used power on #3, so I cannot help there... I doubt this is the problem, but its worth checking, very easy?

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