Random BLE disconnect/re-connect

RE: Random BLE disconnect/re-connect

chrismy — Thu, 29 Oct 2020 00:13:48 GMT

Thanks,

Chris.

RE: Random BLE disconnect/re-connect

Einar Thorsrud — Wed, 28 Oct 2020 12:58:04 GMT

Hi Chris,

[quote user="chrismy"]Thanks for that. My "central" device had its min/max connection intervals set to 7.5ms/30ms, while the slave was 100ms/200ms. By setting the peripheral to 7.5ms/30ms (as per the central device) it is now working very well.[/quote]

Good to hear.

[quote user="chrismy"]Is it correct to say that what is meant by MIN_CONNECTION_INTERVAL and MAX_CONNECTION_INTERVAL is the time the radio is asleep[/quote]

The connection interval itself is the time between the start of two consecutive connection events. The radio will be turned off between the end of a connection event and the start of the next. This min and max connection interval configuration are used to determine the connection interval used for the link. Specifically, the central first dictates the connection interval, but this can subsequently be updated based on suggestions from the peripheral and decision by the central (this is done in a connection parameter update procedure).

[quote user="chrismy"]What is meant by the SUPERVISION_TIMEOUT? Is that essentially the time it needs to have lost packets for before it gives up and disconnects?[/quote]

Yes. The supervision timeout specifies a duration of which a packet needs to be successfully transferred (i.e. sent and acknowledged). If no packet is successfully transmitted during this time, the link will be disconnected due to supervision timeout.

[quote user="chrismy"]Just trying to gain a better understanding of how to configure the system for next time.[/quote]

That makes sense. This post gives a good overview of the connection parameters.

Einar

RE: Random BLE disconnect/re-connect

chrismy — Wed, 28 Oct 2020 00:20:01 GMT

Hi Einar,

Thanks for that. My "central" device had its min/max connection intervals set to 7.5ms/30ms, while the slave was 100ms/200ms. By setting the peripheral to 7.5ms/30ms (as per the central device) it is now working very well.

Is it correct to say that what is meant by MIN_CONNECTION_INTERVAL and MAX_CONNECTION_INTERVAL is the time the radio is asleep? I.e. in my case the radio will now wake up and be active every 7.5 to 30ms? I only ask as previously I seemed to always have between 100 and 200ms of latency between the central device sending data and the peripheral device receiving the data (and this corresponded to the max/min conn interval).

What is meant by the SUPERVISION_TIMEOUT? Is that essentially the time it needs to have lost packets for before it gives up and disconnects?

Just trying to gain a better understanding of how to configure the system for next time.

Thanks,

Chris.

RE: Random BLE disconnect/re-connect

Einar Thorsrud — Tue, 27 Oct 2020 18:03:29 GMT

Hi Chris,

[quote user=""]Are there any timing parameters, etc that I can alter to make the system more "robust"? [/quote]

Yes. Assuming the disconnection reason is timeout due to packet loss, this can probably be improved by looking at the connection parameters. The combination of connection interval and supervision timeout (and paritally slave latency) dictates how many packets can be lost before the link is disconnected due to supervision timeout. Generally, reducing the connection interval and/or increasing the supervision timeout will make the link more robust.

Einar