I am working with a Pixhawk 4 and a Spektrum AR620 receiver. The receiver has a 3x7 grid of pins labelled (-, +, S), and (Batt, 1-6). The reciever says it is a DSM2/DSMX receiver, and I want to connect it to the DSM port of my flight controller. However I am unsure what connections are supposed to be made. Where do I attach the DSM connector wire to the receiver? I tried attaching the dsm header to channel one of the reciever, but then QGroundControl (my mission planner) couldn't read anything from it. The receiver is bound to the transmitter (spektrum DX6i), even while connected to the pixhawk. It is definately reciever signals too (as measured by a voltmeter applied to the signal wire and checking the voltage changed with respect to transmitter movements.) However this was done before hand, and then I plugged it into the pixhawk. The spektrum bind button gives an error "vehicle did not respond to command: MAV_CMD_START_RX_PAIR", no matter what mode I attempt to start it in (I realize this isn't necessary because it is already bound, but I am trying everything). Most of the pixhawk settings are still default, except I set SYS_USE_IO to 0 so that I could use my main motors in the FMU out. The ACT light of both IO and FMU are constantly flashing blue. I am using a basic quad frame. I have tried many steps including holding switch, reflashing firmware, etc. I still recieve the same error, "0 channels detected. To operate pixhawk you need at least 5 channels"

Edit-- Pictures of Reciever and FC connections enter image description hereenter image description here

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    $\begingroup$ Could you describe how you tried physically hooked the RX to the FC? i.e. which pins were connected where? Also, did you remember to configure the PixHawk to communicate with the RX using DSM2/DSMX? $\endgroup$
    – ifconfig
    Apr 1, 2021 at 23:01
  • $\begingroup$ left to right on pixhawk. 2nd pin on dsm connected to signal of port 1 on reciever, 4th pin to + on reciever, and 5th pin to - on reciever. And how do you configure pixhawk to use DSM? Are there special parameters that need to be changed? Thanks $\endgroup$
    – figbar
    Apr 2, 2021 at 19:57
  • $\begingroup$ Could you edit your post with a photo of the connection? Also, have you made sure that the receiver has power? (It appears I was mistaken and the only configuration required on the PX4 is to connect the RX to the DSM port, no software required) $\endgroup$
    – ifconfig
    Apr 2, 2021 at 23:31
  • $\begingroup$ Edited. And yes, the reciever has power when the fc is powered $\endgroup$
    – figbar
    Apr 3, 2021 at 17:33
  • $\begingroup$ Hrm, this really stumps me! I'm not sure I can help anymore without being there in person to reason things out. :( I've tried looking through the PX4 docs (docs.px4.io/master/en/assembly/quick_start_pixhawk4.html) for info on possible software setup and the PX4 pinouts (holybro.com/manual/Pixhawk4-Pinouts.pdf) to see if there is any wiring mismatch, but I can't find anything that appears contradictory to your pictures. Sorry, man! I hope you can figure this out somehow. $\endgroup$
    – ifconfig
    Apr 4, 2021 at 5:56


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