Cannot upgrade from Graupner to Spektrum
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Hello,
In the field we found the Graupner RC on our m500 to have a range of 30-50m, which is much less than what we were expecting. So we upgraded to a Spektrum DSMX RX and DX8e TX which we've worked with at 150m on a Sentinel.
We were able to replace the RX and wire the RC cables per VOXL Flight Core instructions, and we were able to bind via controller and QGC (solid orange light on RX). However, QGC cannot calibrate ("Detected 0 radio channels. To operate PX4 you need at least 5 channels").
We restarted the drone, QGC, and the TX several times, no change.
In voxl-px4-shell I noticed rc_input status says the mode is in SBUS, could this be the issue? I also noticed there is no spektrum_rc command in the px4 shell.
What do you think? Thanks in advance.
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Has there really been no response to this post from April of 2023?
We have the exact same problem but in the other direction. We have a few drones that were shipped with Spektrum radios that were supposed to have Graupners. We received Graupner radio replacements and switched them out as per the ModalAI documentation. We are able to pair with the Graupner HoTT receivers, but the radios are not coming up in QGC.
I e-mailed the modalAI sales team to ask if this was the expected behavior, and they told me that their flight core is open source (which seemed irrelevant) and there was no way to lock it to one radio or another (which I guess implies that the swap should work).
Clearly, something else needs to happen in the configuration in order to get the radio switch to happen. But what is it?
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@mkwan FYI, when we were switching from Spektrum to Graupner, we discovered this setting in the PX4 (accessible via QGC):
RC_INPUT_PROTO
To go from Spektrum to Graupner HoTT, we had to set that to "SBUS". There is a Spektrum-specific setting.
Once we made that change, then QGC started acknowledging that we had a radio connected.
That said, all of our FCv2 boards (which were the ones mistakenly sent with Spektrum although we ordered Graupner) had some problem in the UART connection between the PX4 and the VOXL, and so voxl-mavlink-server reported that there was no UART connection. We are about to RMA the VOXL Flight's to modalAI for them to investigate this UART problem. However, assuming that your PX4-to-VOXL connection is good, I think that the RC_INPUT_PROTO setting above should fix the problem you're having getting the Spektrum radios connected to QGC.