NUS Quiescent Power

[benmack]

I'm using the ble_nus_c NUS client code for a custom 1:1 data link between two embedded nodes, just pinging a few bytes of data back and forth every 3 seconds. Bonded connection. Using nrf_pwr_mgmt_run() in main(). Works a treat but the chip draws about 200uA while asleep, I would like to reduce that as client node is battery powered.

I guess this is because it is constantly listening for a value notification from the peer/periph. However in this application I only need it to listen for a specific timeslot. The client sends data once every 3 seconds, and the peer (mains powered) replies immediately, so client only needs to listen for say 10mS after it sends data. Without dropping the bonded connection.

Can anyone suggest how I would modify the NUS client code to do this?

I'm using nRF52840 (PAN1780 module), SDK 17.0.2, Nordic SES 5.34a

[Vidar Berg]

Hello,

Have you tried to increase the BLE connection interval? The average consumption may come closer to  around 5 uA if you for instance extend the connection interval to 3 seconds rather than the default interval which is between 25 ms to 75 ms.

Note that you can use our online power profiler to play around with different the configuration paramaters such as conenction interval, regulator setting, output power, etc.

https://devzone.nordicsemi.com/nordic/power/w/opp/2/online-power-profiler-for-ble

[benmack]

That's great, many thanks, works very nicely.

I still don't fully understand how the connection interval affects how each end of the NUS link decides when to send data. I don't suppose there is a tutorial on this, or any suggested reading?