High current consumption during bluetooth connection

RE: High current consumption during bluetooth connection

Turbo J — Tue, 06 Jun 2017 09:46:31 GMT

Sounds a lot like a lit LED. Is there a "connected" LED indicator active?

RE: High current consumption during bluetooth connection

CBD — Tue, 06 Jun 2017 07:03:16 GMT

Agreed on all counts. BLE is really only low power due to the nature of the protocol i.e. not requiring a constant RF link, relying instead on very short bursts of data with large time periods between them. To reduce power usage though requires the device sleeping between those bursts.

RE: High current consumption during bluetooth connection

Francesca — Mon, 05 Jun 2017 12:09:45 GMT

Thank you!

RE: High current consumption during bluetooth connection

endnode — Mon, 05 Jun 2017 12:05:26 GMT

Then it's question of Tx power settings, connection interval and how many PDUs are exchanged during each. If you see chip specification and read blog posts about typical power profile of the BLE chip - e.g. here and here and here - you can see that 4mA are not completely unusual. If you want to have it lower then you need to check several things such as what are your typical Tx and Rx power consumption values (and if you can lower them by SW settings or HW redesign) and what is your "sleep" current in between these, if you can run only with certain connection intervals (which might cause some better sleep/Tx-Rx activity ratio) etc.

RE: High current consumption during bluetooth connection

Francesca — Mon, 05 Jun 2017 11:54:34 GMT

I use nrf51822 and softdevice s130. My system count from 10 to 0 second with a timer. After 10 second, the system enters power manage mode. If a bluetooth connection is detected before entering power manage mode, all timers stop. After disconnection all timer reloads. I measure current with a multimeter connected between power supply and groud. During power manage I measure 3.6 uA, during disconnection 10 uA and during bluetooth connection 4 mA.

RE: High current consumption during bluetooth connection

endnode — Mon, 05 Jun 2017 11:44:57 GMT

Hm, very comprehensive description of your system, very easy to answer. But anyway could you give us some more information? Like how your HW looks like, what your FW is doing, on what code is it based on (if applicable), how you measure power consumption over time so you can see what is your base "idle" (= MCU sleep?) power consumption and what are your peeks etc.