nrf52832 - BLE UART performance with Android mobile clients

RE: nrf52832 - BLE UART performance with Android mobile clients

Bragma — Mon, 06 May 2019 14:34:46 GMT

I feel stupid since the problem was caused by me setting min connection time to 300ms. I could not imagine things could be so different because of this settings, since everything went so well with iOS and some old Android tablets. Setting the min to 7.5ms made other clients clients go faster.

I still have some hard time understanding why things went so well with iOS or why the problems appeared after a few seconds with some phones (and not with others...). Probably iOS can send more packets between connection events.

In any case, thanks for forcing me to recheck some stuff I took for good.

RE: nrf52832 - BLE UART performance with Android mobile clients

Bragma — Mon, 06 May 2019 13:33:39 GMT

Hi Kenneth,

your comments made me wonder if it may be related to slave latency (or generically connection parameter updates), because it makes sense. Sadly I've not found anything in my code that may change them. I don't have a sniffer but I have enabled HCI logs in Android and again found an update sent from my firmware, but it contains exactly the parameters I've set and slave latency is 0.

RE: nrf52832 - BLE UART performance with Android mobile clients

Kenneth — Mon, 06 May 2019 11:58:25 GMT

[quote user=""]What's strange is that on some phones, it begins to become slow some time after connection: if the transmission starts right after connection, there are 3-4 seconds where performance is good, then it becomes slow. If instead transmission start 3-4 seconds after connection, it is slow from start.[/quote]

This is leading my to think it may be related to some connection parameter update, where you are going from a fast connection interval with no slave latency, to a slow connection interval (possible with slave latency) enabled. If you have access to an on-air nRF sniffer log or similar we may take a look who is initiating this.

You may in your code check if you have included conn_params_init() in your project and if it by accident is reducing your connection interval.

You may also check out:
https://devzone.nordicsemi.com/b/blog/posts/what-to-keep-in-mind-when-developing-your-ble-andr