Power Profile Example Connection Interval Problem

[garypty]

I am testing the SDK (v12) Power Profile Example with the DK51 and the nRF51 dongle. My purpose is test if I can lower the power consumption as mush as possible. The default value of the connection interval in the source code is 20ms. I can use the dongle and Master Control Panel to receive the notification in this case. Then I tried to extend the connection interval to the longest period - 4s, but then I cannot discover the services successfully.

1. I would like to ask is it correct that I extend the connection interval to lower the power consumption?
2. When I extend the connection interval, I found that the discover services time is also extended, this makes the whole process very slow. My final purpose is actually to develop an client application that would send a notification to the master (for example a mobile app) in a low rate periodically, but sleep most of the time. That is why I try to extend the connection interval.

Thank you.

[Petter Myhre]

1. Yes, but it is not that black & white, see this for more information.

2. Yes. That is a drawback of increaseing it. What you can do is to start off with a short interval, and then try to increase it by sending a CPU request to the central, after service discovery has completed.

[Petter Myhre]

If the connection interval is 2s (and slave latency is 0) the central will send a packet to the peripheral every 2s, and the peripheral will reply to all of these packets (the reply can be empty packet). If you use a timer to send a notification every 5 second, and the connection interval is still 2s, the time since the central received the previos notification would be 4 or 6 seconds.

Most of our examples use the Connection Parameters Negotiation module, but you can also implement something yourself by following MSC I linked to in my answer.