Heart Rate Monitor for FPV drones

Watch your heart rate on Betaflight OSD 💓

See how excited you are while:

• Diving the highest skyscraper 🏙
  
• Flying long-range over the mountains 🏔
  
• Racing in the championship finals 🏁

Get a realtime bio-feedback to improve your flight stability.
Practice to control your stress level 🧘‍♂

Demo flights video:

[](https://youtu.be/yA9xkAsMA1U) [](https://youtu.be/_b7GmlouoaM)

1. HR Monitor

Get any available chest strap heart rate monitor with Bluetooth (for example, Kalenji ZT26D, Magene H64).
Chest strap monitors are recommended.
They are widely used by athletes, because they provide higher precision, not affected by body movements. Although, you may use wrist-strap monitor.

2. ESP32 Firmware

1. Upload firmware to ESP32 board. (How to install ESP32 in Arduino IDE)

2. Find out MAC address of your HR-monitor:

Put on the HR-monitor.
Open "Tools -> Serial Monitor" in Arduino IDE.
Now you can see continuously refreshing list of all available Bluetooth devices around you:

...
BLE Advertised Device found: Name: MI_SCALE, Address: 13:a6:c8:0f:1b:d7, manufacturer data: 580f10ac61b701d7
BLE Advertised Device found: Name: , Address: 50:fe:76:ce:35:ea, manufacturer data: 4c0010054a1c7f72c3
BLE Advertised Device found: Name: Mi Smart Band 4, Address: c2:0d:36:02:8c:31, manufacturer data: 578c110102f3602
BLE Advertised Device found: Name: , Address: 72:89:7b:87:fe:dd, manufacturer data: 4c0010054a1c7f72c3
BLE Advertised Device found: Name: Decathlon Dual HR, Address: f6:de:70:c7:39:fd, appearance: 833, serviceUUID: 0000180d-0000-1000-8000-00805f9b34fb
...

Find the line corresponding to your device.
For example, there is my "Decathlon Dual HR" monitor with f6:de:70:c7:39:fd address in the list above.

3. Replace the address in .ino-file with the address of real device:

#define BLE_HRM_MAC_ADDRESS "01:23:45:67:89:ab"

4. Flash ESP32 again.
   Open "Serial Monitor".
   When ESP board establishes connection with HR-monitor you can see:

Forming a connection to f6:de:70:c7:39:fd
 - Created client
 - Connected to server
 - Found our service
 - Found our characteristic
We are now connected to the BLE Server.
 ...

Now ESP32 board is bound to HR-monitor.

3. Hardware

Wire up ESP32 module to your Radio transmitter as depicted below:

You can use external 5V source (such as power-bank) or connect it to available 5V transmitter outputs (e.g. pins in JR module bay, Radiomaster TX16S bottom connector, etc.).

Trainer port uses 3.5mm 3-pin jack connector.

For advanced enthusiasts:
You can wire it up directly to the main board of your radio. Pads are not labeled usually, so be very careful!!
Here is an example, how I did it for my Taranis Q X7 board:

4. OpenTX

1. Configure Trainer port as Master/Jack. Go to Trainer page to make sure if some variable signal is coming (bottom line).

2. Go to Mixer page. Set one of your channels source to TR1. Now you are redirecting heart rate to RX.

3. (Optional) Copy heart.lua and heart.bmp to SCRIPTS/TELEMETRY folder on SD card.
   Enable it on Display page.

Now you are able to watch current heart rate and the latest statistics plot on the radio display.

Switch between them with a scroll wheel.
Only 128x64 displays are supported so far.

5. Betaflight

1) Flash your FC with Betaflight 4.4.

2) Upload you favourite font with additional heart symbol in Font Manager on OSD tab.

3) Enable Aux value element on OSD tab in configurator.

4) Go to CLI and enter the following:

set osd_aux_symbol = 121
set osd_aux_channel = 8
save

Where 8 is the channel you configured in OpenTX mixer.

Done!

Future plans

• Tests with many different HRM models.
• Lua scripts for bigger screens (212x64, 480x272).

Feel free to contact me in Telegram: @AlexeyStn