Power Consumption of BLE device during inactivity Period

[Brajesh]

Hi All,

I have a following setup :

The peripheral BLE device is supposed to send **(time critical )**data packets to Central device but the transfer is very rare (Can be a few times a day to once in a month). Apart from this, Peripheral device has power constraints as it is running on coin cell battery all which means BLE will have a large period of inactivity. Now my questions are as follows :

• Once connection is established between Peripheral and Central device and data transfer is all done, should Peripheral maintain the connection (SINCE data is time critical and connection may take time to setup next time before sending data) ?

-After data transfer, the device should lose the connection with central device and should set up the connection again when data transfer is needed (SINCE data transfer may not be very frequent some times) ?

• How much current consumption is estimated in ideal connection parameters for the above two scenarios ?

• And also which scenario do you recommend ?

Any inputs/suggestions would be appreciated ?

Thanks in advance.

Brajesh

[Stefan Birnir Sverrisson]

Hi

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?