A noob question about battery

[donne1226]

I wanna make it without the screen.
What is the hourly power consumption？ I wanna use it about 6 - 10 hours. Can you recommend what the battery capacity should be?

[ysoldak]

The head tracker was never optimised for long work from a battery, it constantly communicates over bluetooth with radio (every 20ms) and also does computations -- means never "hibernates" or goes low power to optimise consumption.

Since this was never an expected use case, no tests were made ready to share.

If you have a multimeter, simply measure current draw during operation and calculate battery capacity from there.
I can make such measurement and post here later, but you don't need to wait for me.

---

Example computation (purely theoretical, values are random).

• Measured current draw = 100mA
• Battery capacity = 2200mAh

We don't want discharge the battery to 0%, so usable is around 1200mA.
This gives us ~12 hours operation from fully charged battery.

---

Out of curiosity, what is your use case?

[donne1226]

I just received the XIAO ble sense and flashed your firmware. I did some tests.

But I discovered that the module is not functioning as expected.

First of all, let me clarify that previously I was using an Arduino Nano 33 BLE with the DLKTDR’s firmware. The remote controller is a RadioMaster TX16S with a Bluetooth module installed, and this system was working correctly.

During today's tests, it was observed that the Bluetooth connection was successful, but there was no data output on the trainer page. It only worked correctly once or twice.

Without a Bluetooth connection, I measured a maximum current is 7mA@3.3V with adjustable power supply and multimeter.

Unable to do further tests, don’t know what went wrong.

I use it as a fpv head tracker, I like XIAO board cause it’s much smaller than arduino

[dlktdr]

This sounds very familiar to an issue I had with the our firmware in the past if the module you have in your radio isn't the PARA module. If you have the older non-para module it will connect but no data is sent. The older module required encryption to be enabled.

Yuri, here is all the info we found on that issue headtracker/HeadTracker#22 including some Bluetooth scans.

Although if this is the case then it probably never would have worked even once. Just a thought :)

[donne1226]

Yes Cliff, I am using the Frsky non-PARA module.

I am sure it worked a few times because I can see value changes on the trainer page. When I did the range test, the radio played 'trainer signal lost' and 'trainer signal recovered'. by the way, I found that the connection range is very short and disconnects at less than one meter.

[ysoldak]

Thanks, @dlktdr ! I did not know about this problem at all. That sounds sad. :(
I'll try and look and and see what can be done there to make it work. For experiments, I may need to buy another radio (Tx16s?) and the module.

Thank you, @donne1226 for the tests and the energy consumption measurement!
That's really odd how you describe it was working a bit and then stopped. But let me read through that ticket Cliff mentioned to understand the situation...

[ysoldak]

by the way, I found that the connection range is very short and disconnects at less than one meter.

I’d assume the board has real tiny antenna and not designed for longer distances.
In my experience the range was more like two meters or so. But then, I don’t see that as a problem, why would your goggles be more than a meter away from your radio :)

[ysoldak]

Alright, so apparently there are more than one type of bluetooth module that can be installed in radios.

The correct one (works with this head tracker and equal to installed in recent FrSky radios) is called PARA Wireless Module.

And this is WRONG module, do NOT buy and install it, will not work, at least not with this head tracker.

[donne1226]

Alright then. Thanks anyway. Using such a small board for the head tracker is a great idea！

[ysoldak]

You can still use XIAO with your radio, two options:

• 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.

[dlktdr]

@donne1226 You could also replace the module in your radio with an ESP board (Wroom32, pico32 or c3mini). You can flash some code that emulates the PARA module that should work with this Head Tracker too.

I was looking for a way to remove the dependency of using Frsky modules 😉 It's not super easy to remove the module after it's soldered in, so @ysoldak options are probably the better choice if your not up for a bit of a challenge. Code is here https://github.com/dlktdr/BTWifiModule

[ysoldak]

Nice, @dlktdr !
As a XIAO fanboy, I want to hint on XIAO ESP32C3 board: https://www.seeedstudio.com/Seeed-XIAO-ESP32C3-p-5431.html

[dlktdr]

👍 Should (... hopefully) just have to change these pin numbers to make it work :) https://github.com/dlktdr/BTWifiModule/blob/245e0557da3e2e1c900752333933942caf901a6d/src/defines.h#L26C1-L27

I don't have one of these yet. Also like the size of the XIAO boards, only have the NRF versions currently. I might have to pick one up. I don't want to get too far off topic here, let me know if you ever give it a try 😉

[donne1226]

I'm willing to tinker with the XIAO module to make it functional, but I don't think it's suitable for widespread promotion. First, it's a bit too expensive. Second, there are some technical difficulties.

In the past, I made a tutorial video based on Cliff’s project. Lots of people made their own head tracker modules, which was great!

I found this project a few days ago, and the XIAO board is smaller and cheaper than an Arduino. It's perfect for a standalone module with a built-in battery, so we can get rid of all wires. If you can make it work, I believe that more people will use it.

[ysoldak]

let me know if you ever give it a try

Yes, I can try, have couple of such boards here and can test it by plugging in to PPM on my radio.