Strange behaviour while sending real time data

RE: Strange behaviour while sending real time data

Revo — Mon, 23 May 2016 10:29:27 GMT

thanks, i accept the answer!

RE: Strange behaviour while sending real time data

Petter Myhre — Mon, 23 May 2016 10:26:15 GMT

You can skip the connection parameters negotiation library, so that you don't send a connection parameter update request. You can make the central ignore the connection parameter update request.

RE: Strange behaviour while sending real time data

Revo — Fri, 20 May 2016 15:30:09 GMT

so what do you suggest to solve the problem? At this point i changed the minimum connection interval to 8 ms and the maximum to 10 ms, both on the peripheral and the central; this seems to solve the problem, but it is the best way? Why should i use a large range of possible connection interval instead of a very strict one to be sure to know the "frequency" of transmission?

RE: Strange behaviour while sending real time data

Petter Myhre — Fri, 20 May 2016 13:08:43 GMT

You are using the Connection Parameters Negotiation library. This will send a connection parameter update request after FIRST_CONN_PARAMS_UPDATE_DELAY, then the central device will increase the connection interval.

RE: Strange behaviour while sending real time data

Revo — Fri, 20 May 2016 07:28:57 GMT

Ok thanks, while i wait the answer of more expert people than me that want to take a look at the code i will also check by myself :) btw what are the connection parameters that should affect the frequency of this transmission?

RE: Strange behaviour while sending real time data

FI — Thu, 19 May 2016 22:14:39 GMT

I'd check on the connection interval. At a minimum of 7.5ms, I have seen the jitters bettween each send session was 30ms max on my bench, I was sending hundreds bytes each session pretty consistently. 100ms should not have problem, and the amount of data you are sending is minimal as well, but you should expect some uncertainty in delivery time due to use conditions. Best!

RE: Strange behaviour while sending real time data

Revo — Thu, 19 May 2016 17:08:21 GMT

First of all thanks both for your help. To help you understand i loaded a zip with my projects; one is for the beacon i mentioned (peripheral), the other is for the nrf51 DK that i use to receive the values as central device and send them via uart to the pc (so for Petter, yes i am sending them over uart via the board, and this should happen as soon as a value arrives via BLE from the beacon, as done in the example ble_app_uart_c!).

All the useful connection parameters should be in the files for the beacon since this problem happens not only with the DK but also with the phone as i said, so if you find something suspicious i will be very grateful to you!

RE: Strange behaviour while sending real time data

Petter Myhre — Thu, 19 May 2016 14:42:58 GMT

Could it have something to do with the connection interval? That the connection interval is increased after a while? When you say termite on your pc, are you printing over uart from the beacon kit? If you are, when are printing? Please include the code.

RE: Strange behaviour while sending real time data

David Edwin — Thu, 19 May 2016 14:42:52 GMT

Use the nRF Sniffer and see the ATT Handle Value Notifications on the air to understand your issue better. Post a copy of the trace file for better support.