Android notify sensor data (25FPS)

[Gabriel Gabor]

Hi,

I'm trying to notify some sensor data at a constant 25 data packets per second.

If I set the `MIN_CONN_INTERVAL` to `10 and `MAX_CONN_INTERVAL` to `30` it all works well, I get data at 25 packets/second. This config does work on Android but the `conn_params_negotiation` fails as Android tablet that I use requires a `MAX_CONN_INTERVAL` of at least `40`. As soon as I update the attribute I get 5-6 `NRF_ERROR_RESOURCES`  errors per second lowering the data packets sent per second to 17-18.

I've been trying different configs but I'm not able to make it work at 25fps when the max connection interval is <= 40.

- tried to increase the min_conn_interval to 30 and set the max_conn_interval to 40 (I get `NRF_ERROR_RESOURCES`)

- tried to increase the stack size of the task in which the advertising happens (no effect)

- tried to increase the `SLAVE_LATENCY` to 4 (no effect)

I'm running a bit out of ideas and start to feel that I'm missing something.

P.S. I'm using the NRF52832, SDK v14.2 with FreeRTOS enabled.

Gabriel

[MartinBL]

Unfortunately you can't just assume that all devices are capable of the same throughput. Different BLE chip sets and stack implementations support different connection parameters, different numbers of packets per connection intervals, different packet lengths, etc. So maybe your tablet simply isn't capable of the data rate you want? Here are a couple of informative blog posts on the subject: 
https://punchthrough.com/blog/posts/maximizing-ble-throughput-on-ios-and-android
https://www.novelbits.io/bluetooth-5-speed-maximum-throughput/