Hi,
I have 2 questions:
the api for L2CAP is only for BLE or can also work for BR/EDR? (currently didn't manage to connect with BR/EDR)
I use https://github.com/bluekitchen/CBL2CAPChannel-Demo on iPhone with le_credit_based_flow_control_mode from blue kitchen and the throughput was very low. I also tried to use L2TEST from Bluez (which uses L2CAP BASIC MODE) but it failed to connect
Can anybody help how to increase throughput? The best result I received was 18 kilobyte/second.
Thank you
The CoreBluetooth L2CAP API refers to BLE, not classic BT. With Apple device as central, you will not get good performance, since the channel parameters (L2CAP COC SDU + MPS) and connection parameters can't be set. There's just no API for that (opened FB13742028 for that). I was able to get 36KB/sec for that scenario.
With Apple device as peripheral, you should be able to get up to 100 KB/sec. I have been able to achieve that using an ESP32S3. Note that you make sure to use BLE4.2 DLE (which might not be enabled as default on your system) and a sufficiently high SDU. Apple devices seem to support up to 2048 as SDU.
FWIW, I recently managed to get a 15ms connection interval negotiated (initiated by the peripheral), so 60KB/sec is now possible with an Apple device as the central.