M5Core2-Heart-Rate-Display VS NimBLE-Arduino

Here's an example I made using NimBLE-Arduino: https://github.com/koenvervloesem/M5Core2-Heart-Rate-Display

Have a look at my project https://github.com/koenvervloesem/M5Core2-Heart-Rate-Display. It's using NimBLE-Arduino, but if you prefer to use ESP-IDF instead of the Arduino framework there's also esp-nimble-cpp with almost exactly the same API.

The code will be built using the esp32-nimble crate. The esp32-nimble crate is a wrapper for the ESP32 NimBLE Bluetooth stack. The crate is inspired by the NimBLE-Arduino project. NimBLE is an open source BLE stack fully compliant with the Bluetooth specification providing both host and controller functionalities. NimBLE is also part of the Apache MyNewt project. The ESP-IDF supports only a port of the NimBLE host stack and provides a different controller implementation.

I originally tried using the ESP32 blue BLE library. I ran out of memory. Switched to NimBLE-Arduino, an Arduino fork of Apache NimBLE, a replacement open-source BLE library https://github.com/h2zero/NimBLE-Arduino https://www.arduino.cc/reference/en/libraries/nimble-arduino/ https://h2zero.github.io/esp-nimble-cpp/md__migration_guide.html#autotoc_md46

I like NimBLE-Arduino, and this has a BLE client example that you can adapt to your needs, including both regular reads and notifications. Note that this isn't pure C++, this is using Arduino. There's also a version for use with ESP-IDF: esp-nimble-cpp, with a corresponding BLE client example. The examples for both projects are heavily commented and quite easy to follow.

On the ESP32 side, I use this repo for Bluetooth connectivity: https://github.com/h2zero/NimBLE-Arduino

u/Marijn_fly's is the cleanest solution I can think of but if you're ready to get your hands dirty, there's another BLE library called NimBLE that's massively smaller that the one you're using. Plus I'm an incompetent noob and I find it being easier to work with :D

I recently also looked into this and the NimBLE GitHub and examples helped me a lot to implement this. Source: https://github.com/h2zero/NimBLE-Arduino

Try to implement a driver myself using the NimBLE stack. However, I don't know where to start working with a BLE gamepad.

You indeed need an advertisement packet scanner. Arduino version could be e.g. this: https://github.com/h2zero/NimBLE-Arduino/blob/master/examples/BLE_Beacon_Scanner/BLE_Beacon_Scanner.ino