nimBLE-dat
NimBLE (often written as NimBLE, sometimes people shorten it to "NIM BLE") is an open-source Bluetooth Low Energy (BLE) stack originally developed by Apache Mynewt project.
On ESP32, it’s provided as an alternative BLE library to the default bluedroid stack from Espressif.
Why NimBLE is used on ESP32
- Lower RAM & flash usage than Bluedroid (important if you’re doing Wi-Fi + BLE + other heavy tasks).
- More stable and lightweight for applications that only need BLE (not full Bluetooth Classic).
- Provides GATT server/client, advertising, scanning with a smaller footprint.
- Integrated in ESP-IDF as NimBLE host, so you can choose either Bluedroid or NimBLE.
- In Arduino-ESP32, there’s a library called NimBLE-Arduino (a wrapper around ESP-IDF NimBLE).
Example differences
Bluedroid stack (default ESP32 BLE):
- Feature-rich, supports more profiles.
- Uses more memory (often ~100kB+ RAM).
- Heavier API.
NimBLE stack:
- Lightweight (~50% less RAM/flash).
- Faster connection / lower latency.
- Still supports most BLE use cases (advertising, GATT server/client).