Device does not sleep after disconnection.

[Chitra]

Hi,

 

I’m trying to measure the current on NRF52840, SDK 17.0.2.

I have modified the HeartRate Measurement example’s advertising parameters as PLper my requirement.

I observe that while my device is advertising, the current is around 40 Micro Amps and the sleep current is 3.2 Micro Amps.

Once I connect and disconnect to the device using NrfConnect, the current is 30 Micro Amps and does not drop back to 3.2 Micro Amps.

Why is my device not going to sleep after disconnection?

 

 

Thanks,

Chitra

[Chitra]

Thanks for your reply, Vidar.

I’m not using the ble_advertising_init(), I have modified the advertising_init(), to use sd_ble_gap_adv_set_configure() as followed in the ble_app_blinky example.

Also, I have modified the application to transmit the beacon once every minute.

With my changes, the device sleep current is around 3.2 Micro Amps(with logging turned off)  which seems reasonable.

But, why does my device fail to go to sleep after a Connect and Disconnect?

Kind Regards,

Chitra

[Chitra]

Thanks,

 

I tried disabling the ‘BLE_ADVERTISING_ENABLED’ configuration setting in the sdk_config.h, it did not fix the issue.

Regards,

Chitra

[Vidar Berg]

You would be measuring ~6mA if the CPU did not go to sleep. You may try the project I uploaded in my previous post if you want to try replicate my results.

[Chitra]

My application has to be power optimized, 30-60 Micro Amps during advertising is fine. But I need to get back to 3.3 Micro Amps during sleep.

The sleep current is 3.3 Micro Amps until I Connect and Disconnect. But why does it not go down to 3.3 Micro Amps even after disconnection?

Any idea which part of the code I need to check?

Regards,

Chitra

[Vidar Berg]

Maybe you could you upload the full project here (i.e. a zip of the project folder)? That way will know we are testing with the exact same configuration.

Also, the idle current with the UARTE peripheral enabled is around 30 uA on the nRF52840, so it may be worth double-checking if it is disabled.

[Chitra]

Hi Vidar,

Please find the attachment of the project for your reference.

Thanks,

Chitrable_app_hrs_pwr.rar

[Vidar Berg]

Hi Chitra,

Thanks, but I'm still not able to replicate the problem. The sleep current remains ~3 uA after disconnections. I even tried the .hex file from your build "\ble_app_hrs_pwr\pca10056e\s112\ses\Output\Release\Exe\ble_app_hrs_pca10056e_s112.hex"

[Chitra]

Thanks Vidar,

I replaced the battery on my dev board and I too see that the sleep current drops to ~3 uA after disconnection.

Thank You very much for your support.

Regards,

Chitra

[Vidar Berg]

Thanks for the update. Glad to hear that it works now. I'm not sure why or why the battery level impacted the measurement like this to be honest.