Power Consumption of BLE device during inactivity Period

RE: Power Consumption of BLE device during inactivity Period

Stefan Birnir Sverrisson — Fri, 06 Feb 2015 15:19:17 GMT

As Kaku suggests, broadcasting your data without connecting could be a valid option for you if the central does not have any current consumption requirement. But then every device in the area can pick up the advertising data. The nRF51 could stay in System off mode (~0.6uA) with this method but you will have to wake the device up with a button press, otherwise you will have to stay in System On mode (~3uA).

Another option would be to stay in a connection with high slave latency. Then the peripheral (the nRF51 device) would need to send very infrequently, but still could give a good response when you need to send your data. When in a connection, power budget can be held relatively low on the central device too, and your data will only go to the connected device. You could maintain the connection with ~4uA peripheral current consumption.

The third option would be to disconnect and then reconnect when data transmission is needed. How long time connecting will take can vary, but if you have connected before with the central device and do not have any current consumption requirement on the central side, then you can do a direct advertising where the peripheral device will connect very quickly with the central device. The device will consume a lot of current when direct advertising but you could stay in System Off mode with ~0.6uA instead when inactive.

So, the best scenario depends on your requirements. Perhaps you can share more about your requirements?

RE: Power Consumption of BLE device during inactivity Period

kaku — Fri, 06 Feb 2015 01:45:34 GMT

Hi, In my scenario it has no requirement to connect peer device, which is just to send adv packet. I'm not sure what your system will go to work or have design. But, if a chip is supposed to be putting system off, then will wakeup from any event like GPIO or reset, I think it would take some time in order of a hundreds ms, but if the chip is supposed to be always putting system on, the time until starts adv signal would be shorten. Anyway, I think you need to check this interval until starts adv signal on your board. Thanks.

RE: Power Consumption of BLE device during inactivity Period

Brajesh — Thu, 05 Feb 2015 11:32:47 GMT

okay , That makes sense but how much time connection setup is gonna take every time since data is time critical ?

RE: Power Consumption of BLE device during inactivity Period

kaku — Thu, 05 Feb 2015 10:19:28 GMT

Hi, In your scenario, I think it doesn't always need to connect between central & peripheral device. If your central(scanner device) has huge battery power, it keeps scanning a broadcasting device(that has coin cell battery), then broadcaster just to send short data as advertising packet once a day or month. How is this ?