OSD on a Spektrum transmitter

Banaari · July 24, 2026, 8:07am

Last night I upgraded the firmware in my Spektrum NX6 transmitter - it’s now at 4.02.

This evening while footling about, to my utter delight I suddenly starting to see “PreArm” and/or “low heater temperature” messages appear on the transmitter screen - which must be coming from the flight controller. It seems to be intermittent - as if only displayed when the controller decides to send the message.

I wasn’t aware this was even possible and can’t seem to find any documentation on the subject.

Can anybody shed any light?

andyp1per · July 26, 2026, 7:38am

We send the telemetry that we can over SRXL2 if you are using that. Some limited support on DSMX as well.

Banaari · July 26, 2026, 9:06am

Brilliant!! Indeed yes, SRXL2 from a CubeOrange+.

Are you able to elaborate on “that we can” (no problem if not) and/or whereabouts would I go looking in the source for the nitty-gritty?

andyp1per · July 26, 2026, 6:59pm

github.com/ArduPilot/ardupilot

libraries/AP_RCTelemetry/AP_Spektrum_Telem.cpp

master

/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
   Spektrum Telemetry library, based on AP_Frsky_Telem.cpp
   See https://www.spektrumrc.com/ProdInfo/Files/SPM_Telemetry_Developers_Specs.pdf
*/

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Banaari · July 26, 2026, 10:29pm

Thank you sir!!

Looking at that code - would I be correct in thinking that the receiver’s own sensor values (the AR6610T I’m using has a built-in barometer and battery voltage port) would be overridden by controller / ArduPilot supplied values?

andyp1per · July 27, 2026, 8:46am

No idea, sorry - depends whether they are injecting those values on the wire. You might get both. On TBS we advise people to turn off the RX voltage monitoring.

Banaari · July 27, 2026, 8:02pm

I feel a custom build coming on The way the a/c wiring evolved I’m monitoring battery voltage on the second port which I believe would be instance 1 not the default instance 0. But overall this means I can solve the issue with software rather than running a second wire… and omit the on-board display I was going to have to wire in. What a fantastic piece of code!!!