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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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?

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.

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

Yes, I tried BEC on out #1 too. Right connected I think, receiver gets powered and yes, it has an status LED which lights up. Cables are connected as you mentioned, as you can see in image attached.


Yes, RX is bounded to TX. I tested it again as you mentioned, see the image attached. RX has power, when I move channel 2 on TX the servo moves correctly. So there is no problem with that I think. Tried APM again with test -> pwm, nothing. It always puts out "1200" on each and every input, see image 2 attached.


might want to check your soldering on all of the pin headers as well

Doug, is there a way to identify, if there is a problem with the firmware? I did it all again:

1. Gets latest APM Mission Planner 1.066
2. Firmware -> ArduPilot Mega, it downloads 2.23, uploads it to APM, checks it, done

3. Firmware -> APM Setup to Flush EEPROM, Reset

4. Doing some testing in terminal, version is correctly shown as 2.23, magnetometer and gyros etc. work perfectly

But still no rx input ...

Done, I did the following: take a multimeter and check that all +/- of all inputs and outputs are connected with each other, all fine. To check the signal pins I powered off the APM, plugged in the BEC power on out #1 and one input from the receiver. APM starts up, PPM-LED begins to flicker - that should be a good sign. After that I removed the single input and plugged it in the next input, restart APM, PPM-LED flickers again, all fine. So I checked all 8 inputs and I think its nice.


So am I wrong if I think, that all the cable stuff seems to be right but that the PPM-encoder eats all inputs?

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

Same issue here:

All sensors providing data, XBee and GPS both work, all signals from my RX are being relayed to the servos through the APM, but Mission Planner does not register the signals. Also stabilize mode does not result in any servo movement.

Until you setup the radio in the Mission Planner APM won't output servo commands in stabilize mode. 


What radio are you using? There are special instructions in the manual for Spektrums, which have given some people problems. 

That is actually good news, it is this stage that stage then where things are going wrong.  When I try to setup the radio in the Planner I get 1200 min/max on every input channel and no response from the software to the instructions coming from the Rx. All the servos are moving, but no joy on Mission Planner registering anything (switches like the AP control on channel 8, control surface movements and throttle on 1-4). I don't know if it is relevant but I also tried joystick control, no joy their also. Thinking possible software issue, I tried HK ground control and again no joy.

Equipment: Aurora 9 (w/ optima 9 Rx)

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