MAVLink data displayed on OpenTX (9X/9XR/etc) radio screen via OpenLRS, plus telemetry pass-thru to PC

FYI, it is very easy to display convenient live MAVLink data on your (9X/9XR/etc) radio screen using OpenTx and OpenLRSng. You can also simultaneously pass the data to Mission Planner running on your PC via a USB FTDI cable (3v3).

I use a 9XR radio running OpenTX compiled with EXT=MAVLINK (or installed automatically using the Companion9X app by ticking MAVLINK extension), and the latest version of OpenLRSng (Gitsly branch). I use a cheap OrangeRX Tx module ($29) in the 9XR, and OrangeRx Rx module ($19) in the plane. This gives me 433MHz RC control over the plane, as well as a MAVLink-compatible serial link (57600 baud, 19200 datarate). No need for extra XBee/3DR/RFD radios.

With this cost-saving combination, I get MAVLink data displayed on my 9XR screen (mode, nav, link, batt, GPS, etc), and by plugging a FTDI cable between my Tx module and laptop, Mission Planner also gets live flight data - normal display of flight data, maps, etc.

The upside is low cost and only the 433MHz RF channel used (no extra modem transmitting other frequencies), which also gives power consumption, weight reduction, and possible range benefits (less RF near antennas as opposed to using a separate telemetry radio).

I just thought it was a setup worth mentioning for new and budget conscious DIY-ers, or those wanting a second, less hard-core setup, such as on a slope soarer.

The original setup discussions (parts out of date now) and procedure summary is here: http://www.rcgroups.com/forums/showthread.php?t=1913501

Devices are here:
- OrangeRX LRS UHF Tx module 100mW (~$15): http://www.hobbyking.com/hobbyking/s...095&aff=913237

- OrangeRX LRS UHF Tx module 1W (~$30): http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=...

- OrangeRX LRS UHF Rx (~$15): http://www.hobbyking.com/hobbyking/s...096&aff=913237
- Turnigy 9XR radio (~$50): http://www.hobbyking.com/hobbyking/s...544&aff=913237

NOTE: for 9X/9XR you will need to make a few small mods to the module connector pins on the 9XR/Tx to enable bi-directional serial I/O.

Special thanks to Kha (OpenLRSng), Martin (Gitsly/OpenLRSng) and Rienk (OpenTX/MAVLink) to get this operational.

Rienk's dev thread: http://diydrones.com/forum/topics/mavlink-ardupilot-opentx-extension

Companion9X for radio firmware: http://www.open-tx.org/downloads.html

Martin's Gitsly/OpenLRSng firmware for Rx/Tx modules: https://github.com/gitsly/openLRSng

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This is great work!

I've got some parts on order to try this out, but I'm also interested in controlling my quad via an android tablet without an RC tx (possibly via a bluetooth game controller for manual flight as well). Is there some cheap hardware I could use to connect up Droidplanner or Andropilot directly to the Orange LRS rx?

And as a bonus: The orange LRS hardware seems to be limited to a slower baud rate than the 3dr radios: is this a hardware limitation, or software?

Does anyone know someone in the Essex area that maybe able to do this mod for me (for a price :) ).

Update to this guide: 

It presently seems much better to use the Gitsly branch of OpenLRSng on your RX/Tx modules. Get the latest Arduino code here: https://github.com/gitsly/openLRSng . Thanks to Martin for maintaining that code. I get about double the telemetry bandwidth under same conditions as compared to Kha's main trunk code. Martin has incorporated all functionality of the trunk, but has more thorough MAVLink support.

In summary:

- Do the above hardware mods to 9XR and ORX OpenLRS modules.

- On OpenLRS Rx/Tx compile and run this firmware: https://github.com/gitsly/openLRSng

- On 9XR use OpenTX default binary firmware provided by the latest release Companion9x app (make sure to tick "MAVLINK" extension box when you click preferences, and it will auto download firmware and offer to flash it): http://www.open-tx.org/downloads.html 

There is currently a small issue with display of some parameters on the 9XR, but this should be sorted shortly.

There is no need to use Ctrl-T in Mission Planner to skip normal APM connection - normal connection works fine now!

I use Baud 57600 on APM telemetry port, OpenLRS Tx, and 9XR radio. Make sure to set baudrate in 9XR/OpenTX radio settings to 56700 also (long press left from main screen). However on OpenLRS,  "datarate" is set to 2 (19200) to leave sufficient RC bandwidth using old-fashioned CLI terminal method. I believe Kha's Chrome configurator can also be used to set that parameter. In any case, I use the CLI method to set the following params:

RF_POWER 7

CARRIER_FREQUENCY 435000000

CHANNEL_SPACING 5

HOPLIST 22,10,19,34,49,41

DATARATE 2

BAUDRATE 57600

SERIAL_DOWNLINK 29

It's really quite impressive how rapidly the data is updated on Mission Planner in this manner. Pretty much same experience as using XBees/etc radio modems. Saves power, weight, $, and reduces RF usage/interference. And you get to see the telemetry reports (eg current mode) displayed on the 9XR, not just Mission Planner :)

It must be possible to hookup another OpenTX receiver to a laptop over an FTDI cable in order to prevent needing to run a cable from the transmitter. Has anyone tried this? I imagine it should be pretty straightforward. I think this would give you the best of both worlds.

Yeah thats a good idea.

The RX modules are pretty cheap. You would just need to pair the RX with the other RX - i imagine this could be done in the openlrsng google chrome extension?? Anyone know if you can pair multiple RX's?

I was going to do the above mod to my 9XR then saw the intricate sodlering inside the 9XR - No Way!

I think i may need the extra RX. Whats the best way to get the serial data out of the orangerx RX in the 9XR into a ftdi usb adapter. I didn't see that mod in the thread - only the 9XR displaying telemetry?

Thanks

Another option people have tried is to attach a bluetooth serial tx inside/on the TX module, then you can connect via bluetooth to your tablet/computer to eliminate the cable.

IF you only want to connect your tablet to receive the mavlink just use a $6 bluetooth module connected to the LRS...

Yeah that would be perfect.

Do you know where there would be a guide on how to do that? I would need a usb Bluetooth adapter for my tablet as well i think, as i don't think its built in. Would i then just click the normal connect button in droidplanner?

Thanks

Why is the mod required on the 9xr?

It seems like the firmware could just use the signal coming in on the RF pin (that's completed in the OpenLRS TX module mod)

Thanks for the excellent post! What hardware modifications are you referring to, though? You say "the above hardware mods" but don't explicitly reference them anywhere.

This is really awesome!

They came out with a 1W version, so long range is possible! Unfortunately the RX only has a 100mw transmitter so upgraded antennas are a must :/

Hi, 

I've just finished with success this mod with hobbyking Orange OpenLRS 1W UHF with Orange OpenLRS RX 9 channel 100 mW- APM 2.5 and 9XR.

(http://www.hobbyking.com/hobbyking/store/__43852__OrangeRX_Open_LRS...

(it's the same mod as for the 100mW orange UHF TX - just remove R2 and add wire between RF and TX )  

It's works quite good but screen about telemetry need's to but improve.

Congrats for everybody in this great project !

I would like to help if I can. 

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