Options for radios without built-in PARA wireless trainer

[ysoldak]

While the Head Tracker tested and works nicely with recent FrSky radios that have PARA wireless trainer built-in, there have been several cases recently people can't connect Head Tracker to their modified Radiomaster TX16S.
The modification involves installing a bluetooth module inside the radio.

Apparently, there are different bluetooth modules on the market that look almost the same and only one of them (most expensive, of course) shall actually work, w/o need for flashing any firmware on it.

I can not verify this claim myself, due to lack of hardware, but according to one gentleman in discussion of the issue in Cliff's Head Tracker, the module with "PARA" in name and price tag of ~$30 actually works. This is what he has to say:

BTW I can confirm not just T16 but also T16s works with "FrSky ACCESS PARA Wireless Module"

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Take a look at the WRONG module, that shall not work with this Head Tracker, so DO NOT buy it!

Worth to mention, Cliff's Head Tracker does work with $10 bluetooth module, so if you already soldered the wrong module to your radio, your best bet would be use that head tracker firmware.

I have no plans to implement support for $10 bluetooth module in this project, at least not myself.
But feel free to contributes code that works with that module, make a PR and we take it from there.

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The options you have with radios w/o built-in PARA wireless trainer:

• Use PPM, wired connection;
• Use Arduino Nano 33 BLE on the radio side as a helper module (from Cliff's project), HT will connect to it wirelessly (same protocol) and helper module will connect to your radio via SBUS or PPM;
• Use proper PARA module installed in your radio;
• Use an ESP32 board in your radio and flash BTWifiModule firmware on it.

[Wolle2602]

Hi ysoldak,
recently I have bought your Walksnail 3D print with the Seeed Studio XIAO BLE Sense board and flashed release v2.4.3 to it. In my Radio (TX16S) I have the diy ESP32 board installed (BTWifiModule).
It works, but I have periodical connection losses. On another goggle I have an Arduino Nano 33 BLE (Cliff's code) which works fine with the ESP32...
Do you know where the problem is?

[ysoldak]

Arduino Nano 33 BLE is a different board and may have antenna positioned better, etc.

If HT on XIAO BLE board reconnects instantly, it means the firmware does not reboot or hang, so must be something with Bluetooth connection.

Not familiar with Frsky BT module (not PARA), probably not relevant here...

Have you had a chance to try on the open, away from other devices?

[Wolle2602]

Hi ysoldak,
I tried somewhere without frequency noise, didn't change a thing.
I also bought a 2nd Xiao board to find out if it is damaged - it is not...
Next thing I can try is wiring a PARA module to my Radio (have one somewhere...).
(TX16S MKII mainboard is not made for that)

Want your Module to work, but still don't have a clue where the Problem might be.

[ysoldak]

Sorry can't help you here. Would need to reproduce first, but it works stable for me...

Some random idea: if you detach screen, button and all and just power XIAO BLE (with HT firmware flashed) via USB-C cable. Connect to it from your radio and see if link is stable? What I'm thinking is the battery, or display or something else around XIAO can disturb bluetooth waves / block antenna. Experiment with distance from your radio...

Anyway, good to have the information here, so others can see there may be a link issue between PARA module installed in TX16S and XIAO.

[Wolle2602]

Last reply, because it works now! I have installed the PARA BT module in my Radio now...

I tried all your ideas but at the end my only thought is that maybe BTWifiModule and your XIAO board/firmware are not compatible...

[ysoldak]

Great! Happy head tracking!
Yeah, I probably misunderstood you from start. It is known to work with PARA BT module and that ESP32 board is just an experiment (or at least it was not long time ago).