NUS example, when connected, see current pulse 50ms interval

[James168]

ncs v2.9.0

nRF52832 DK (NUS central)

nRF52840 DK (NUS peripheral)

1) When connected, see the empty PDU from peripheral to central about 100ms interval.

2) To use the power monitor to watch the current consumption, the current pulse is about 50ms interval, why it's different?

  

[James168]

I send "Hello\n" 6 bytes from peripheral to central to test peripheral TX current consumption, and I see many pulses more than 6 in the power monitor. It continued about 420ms, how to explain it and how to improve it?

I expect to see the current like the "Online Power Profiler for Bluetooth LE".

The following is the power monitor screen captured,

zoom in

[James168]

Hi Jared,

I have another question to send "Hello\n" 6 bytes about current consumption, can you reply also?

[Jared]

Hi,

1. Have you set the development kit to nrf Only on switch 6? 
2. I think the Bluetooth power profiler sample is better for power profiling. 

Jared 

[James168]

1) I am using nrf52840 dongle for test, but using nrf52840 DK and sw6 to "nRF only" almost the same current value.

2) Can power profiler sample packet be captured by wireshark? I see nothing when advertising. 

[Jared]

ok, on a second thought, the power profiler sample does not support the dongle as it requires you to press button 1 to wakeup the device from sleep and start advertising. 

Maybe you can share the modified code that you use here, and I'll check if I can give you any suggestions to decrease the current. 

James168 said:

I used button to trigger send the packet before, and today I change to use timer interval to send packet when timer is expired and the current pulse happened just once. It seems normal now. But the power consumption is large than the "Online Power Profiler for Bluetooth LE" about 30uA.

regards

Jared

[James168]

1) I attach the code, and most of the modified codes are between line 587 to line 692, the other modifications are used to disable the LED and UART.

To use send_data() to send the packet 10s interval, the connection interval is 100ms.

4188.peripheral_uart_v290_low_power_250221_connected_send_data_10s_interval.7z

2) About run the power profile sample, I did press the button 1 or button 2, and I can see entering the system off mode from the log.

I doubt the sample use 

bt_le_ext_adv_start(adv_set, &connectable_start_param);

to send the advertising, does the wireshark can capture the extended advertising packet?

[Jared]

Hi.

James168 said:

Yes, using the latter peripheral_uart sample to send packet to central_uart, the current consumption is higher than online power profiler. I disable the UART in prj.conf and use timer expire to send packet from peripheral to central.

2) I send 13 bytes from nRF52840 dongle (peripheral_uart) to nRF52832 DK (central_uart), and change connection interval to 100ms, so the measured current consumption is about 102 µA, and the online power profiler is about 79 µA as the following.

Online power profiler application does only estimate the current consumption of the BLE stack. Anything extra in the application such as timers will consume additional current that is not taken into consideration by the estimation. I think what you measure is within what is acceptable.

regards

Jared