Current measurements in low power modes

[sara]

Hello, I am working on a project that uses nrf52832 and I need to put that device and in the system on mode. For that, I want to measure the current in the system on and system off mode which is 1-2 uA and 0.2 uA respectively, but I do not get these values. Can you provide me with the code for which I can measure the current in system on and system off mode to get the above values? I had used ble_app-pwr-profiling example to get the values but I did not get the desired values.

[sara]

I tried with the ble_app_pwr_profiling example , and changed APP_CFG_NON_CONN_ADV_TIMEOUT macro to 5 , but the values I got are not as per the specifications. 

- When I short SB9 and cut SB12 then I recieved 195.372 uA 

-when I cut SB9 and short SB12 then I get 905.705 uA average current

 I want the current measurements for system on mode also

[Edvin]

Can you try to power it via the USB cable instead of the external power input? And then follow the setup exactly as described here:

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_ppk%2FUG%2Fppk%2FPPK_user_guide_Quick_start.html&cp=6_6_3

Does that show reasonable numbers?

[sara]

I tried for the ble_app_pwr_profiling example and got the current between the peaks as 2.695 uA average current which I think is the system on mode current now next is how to get the system off mode? As even if I am not connecting the device I think it is entering the system on mode i.e idle state and not system off mode.

If I am wrong then which current is it that I got as 2.695 uA between the advertising peaks? system sleep mode on or system sleep mode off current? Because if it was system off then current should be much lower than the measured current.

And when I checked for the pwr_mgmnt example I got the system off current as 0.731 uA and system on current as 2.801 uA.

Thank you Edvin for your time and support. I have got these readings because of your guidance. Waiting for your response for the question I have regarding ble_app_pwr_profiling example.

[Edvin]

sara said:

I tried for the ble_app_pwr_profiling example and got the current between the peaks as 2.695 uA average current which I think is the system on mode

 Yes. That is system on mode (as long as you call sd_app_evt_wait() in your main-loop).

If you are using the softdevice, you can't be in system off mode, hence my conclusion that you are in system on mode. If you are in system off mode, you need a physical interrupt in order to wake up the device, so you can't do this in between advertisements or if you are connected.

System off mode is not entered until you call sd_power_system_off(), which typically happens in:

on_adv_evt() -> case BLE_ADV_EVT_IDLE: -> sd_power_system_off();

In the ble_app_pwr_profiling example, the advertising timeout has a different name. It is the one called APP_ADV_DURATION, which is originally set to 30000*10ms. If you change the define to 500, it will time out after 5 seconds.

[sara]

Thank you -for the clarification regarding the system off mode. I was a bit confused because of the condition given in ble_app_pwr_profiling example as below:

if (!m_is_notification_mode && !m_is_non_connectable_mode)
{
// The startup was not because of button presses. This is the first start.
// Go into System-Off mode. Button presses will wake the chip up.
        nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF);
}

I had changed APP_ADV_DURATION to 500 but still continues advertising. 

Because even if I am not connecting via nrfConnect application then also it remains in the system on mode I mean advertising and not in system off mode.