BLE data length extention Thingy 52

RE: BLE data length extention Thingy 52

Rilleaa — Tue, 19 May 2020 09:03:56 GMT

Okey yea mabey that part is out of my control then.

Any way of knowing what MTU size the two devices? From the ble sniffer i see when i connect with my Iphone 6s that it uses MTU size 185 but with the raspberry pie i cant see any MTU size.

I have tried to send bigger packages bigger than 20 bytes from thingy 52 to both iphone and Raspberry pi it works on the iphone but not on the raspberry pi i just recive the first 20 bytes in the array of data that was sent to sd_ble_gatts_hvx().

I attatched my sniffer logs i case you have time to have a look at them :).

//Rilleaa

devzone.nordicsemi.com/.../ThingyToIphone6s.pcapng devzone.nordicsemi.com/.../ThingyToRBP.pcapng

RE: BLE data length extention Thingy 52

Kenneth — Tue, 19 May 2020 07:44:23 GMT

It is the master that control most of the parameters, so as a peripheral device you can only request for faster interval and longer length. So it could be limited by the rasperry pi yes.

Kenneth

RE: BLE data length extention Thingy 52

Rilleaa — Mon, 18 May 2020 21:29:28 GMT

The for the reply Kenneth.

I have implemented something similar by following this thread https://devzone.nordicsemi.com/f/nordic-q-a/553/dealing-large-data-packet-s-through-ble/2839#2839 it works fine and i get around 3kB/s of throughput. Is there any way to increase this even further? I looked at this link:
https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsds_s132%2FSDS%2Fs1xx%2Fble_data_throughput%2Fble_data_throughput.html&cp=3_4_2_0_16
and it indicates that i would be possible to increase the speed more. Or is it limitations in the central device (in my case a raspberry pi 4) that i cant change thats is limmitning the thorughput speed?

//Rilleaa

RE: BLE data length extention Thingy 52

Kenneth — Mon, 18 May 2020 15:43:54 GMT

First of all the connection interval should be as short as possible.

Then you should call sd_ble_gatts_hvx() as fast as possible until NRF_ERROR_RESOURCES. Then you need to wait for BLE_GATTS_EVT_HVN_TX_COMPLETE before you can repeat calling sd_ble_gatts_hvx() as fast as possible.

If you include gatt_init() in your application, then the callback provided in gatt_init() should provide you with the max length that is supported in the callback handler after the supported MTU exchange have completed. After that you can call sd_ble_gatts_hvx() with a length that equal the max supported length in the callback handler.