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

[Jared]

Hi there,

That looks indeed like current consumed from the Radio, is the sample unmodified?

Could it be that the interval starts at 50 ms and then increases to 100 ms later? Do you see the same if you measure current after some time has elapsed?

regards

Jared 

[James168]

Hi Jared,

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

[Jared]

Can you zoom into one of the "pulses"?

[James168]

1) connection interval is unmodified, the default values are

#define BT_GAP_INIT_CONN_INT_MIN 0x0018 /* 30 ms */
#define BT_GAP_INIT_CONN_INT_MAX 0x0028 /* 50 ms */

I think maybe the sniffer can't capture all packets for channel hopping condition, so the interval changed to 100ms in the wireshark.

I got empty PDU packets interval 50ms sometimes in the wireshark.

2) To send "hello\n" once waveform as the following, the sampling rate is 32k/s, maybe not the real waveform.

zoom in 

zoom in

It seems have 6 spikes matching the 6 bytes data, but why it continued many times in 10ms interval?