Not able to send large number of samples over BLE

RE: Not able to send large number of samples over BLE

Kenneth — Tue, 24 Sep 2019 07:37:46 GMT

29samples * 9bytes = 261bytes which is actually a decent large packet.

[quote user="shr217"]but am not able to get it to send greater than 25samples at a time[/quote]

This sentence doesn't make sense, there must be some kind of error code somewhere (you may be ignoring it if you are not checking return err_codes).

RE: Not able to send large number of samples over BLE

shr217 — Tue, 24 Sep 2019 07:15:30 GMT

My particular application requires a process where it is interfaced with the ADC. I have a constraint that I cannot send the data simultaneously while sensing, which requires me to store it and then send.

So overall, it works such that I sense the data, then send and again sense. This process repeats. I need to send a burst of data.

I am using ble_nus_data_send to send the data array

I tried to change the BLE_GATT_ATT_MTU_DEFAULT, but am not able to get it to send greater than 25samples at a time

RE: Not able to send large number of samples over BLE

Kenneth — Tue, 24 Sep 2019 07:02:51 GMT

There is information missing here, for instance you are not writing how you are sending data (write command or notification), and if the softdevice api call to send data is returning any error code.

You write you want to send data in 100bytes "chunks" but how do you know that is the most efficient data size. Typically you want to include nrf_ble_gatt_init() if you want to send data that is longer than default 20byte, this can be handled by adding gatt_init() to your project.

I suggest to check out:
https://devzone.nordicsemi.com/f/nordic-q-a/41629/what-is-the-difference-between-data-length-and-mtu

Also you may find this useful:
https://www.novelbits.io/bluetooth-5-speed-maximum-throughput/