How can I control an ESP32 with a TikTok Bluetooth controller?

PlatformIO IDE
1

I have a Bluetooth LE device, a „scroll ring“ from Amazon

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Technically, it is an HID device that sends equivalents of shutter button presses and swipe up gestures to a connected device.

I have been searching for weeks but have not found a way to get the ESP32 to connect/pair with it and detect the key presses.

I suspect this might be because the device appears as a keyboard/HID on a regular computer. Conceptually, I understand how to detect the services of the controller and start the bonding process.

However, I am unsure how to perform the simplified BLE connection process (without PIN exchange, Just Works pairing) and how to use the device as an input device.

I just need to detect the different key presses! Any guidance or examples would be greatly appreciated. Is there a recommended library to use?

Thank you very much.

2

Does a simple BLE scan even see the device? If the Amazon screenshot it is right and a regular phone can see a “ATG-SJL” device, then so should an ESP32.

https://github.com/espressif/arduino-esp32/blob/master/libraries/BLE/examples/Scan/Scan.ino

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You might need to at first unpair the device from your phone to free it up.

ESP-IDF does have an example in which the ESP32 acts as a BLE HID host:

https://github.com/espressif/esp-idf/tree/master/examples/bluetooth/esp_hid_host

3

Yes, the device is visible and has been disconnected from other devices.

The ESP-IDF example looks promising. Thank you for pointing it out.

I am currently away from compiler, but I wonder in general how to convert / adapt the example to something that lives in the „Arduino world“ in platformio.

4

Update: Got the example to work on a random ESP after I installed ESP-IDF in Visual Studio Code on my M2 Mac. Very satisfying.

Learnings so far:

  • Had to set the Crystal Frequency from 40 to 26
  • The BLE device sends a bunch of weird input reports for click, double-click and long press respectively. I’ll see where this will lead me.
5

1. Single Click Input Report

  • Report ID: 2 (GENERIC INPUT REPORT)
  • Length: 7 bytes per report

Input Report Sequence:

07 06 70 07 80 0c 01 00
07 06 70 07 28 0a 01 00
07 06 70 07 fc 08 01 00
07 06 70 07 d0 07 01 00
07 06 70 07 a4 06 01 00
07 06 70 07 78 05 01 00
07 06 70 07 4c 04 01 00
07 06 70 07 20 03 01 00
07 06 70 07 f4 01 01 00
00 06 70 07 c8 00 00 00
  • Description: This sequence represents a single click gesture.

2. Double-Click Input Report

  • Report ID: 2 (GENERIC INPUT REPORT)
  • Length: 7 bytes per report

Input Report Sequence:

07 07 70 07 70 07 01 00
00 07 70 07 70 07 00 00
07 07 70 07 70 07 01 00
00 07 70 07 70 07 00 00
  • Description: This sequence represents a double-click gesture. The alternating pattern of reports corresponds to two quick presses and releases of the button.

3. Long Press Input Report

  • Report ID: 3 (CCONTROL INPUT REPORT)
  • Length: 3 bytes per report

Input Report Sequence:

01 00 00
00 00 00
  • Description: This sequence represents a long press gesture.