ble-connection power consumption=1mA

[Daniel.Chiu]

Hallo everyone!

I need very low consumption when BLE working. according to S110 SDS, BLE power profile section, when BLE in idle-connect, there is Ion+Irtc+Ix32k, same with advertising idle, about 3.7uA.

My custom board has nrf5188,external 16M crystal, 3v battary, config ble_stack_init with RC32k(8000ms CALIBRATION), used peripheral power contral to disable all unneed peripheral, just maintain softdevice needed(RADIO,RTC0,TIMER0,CCM,AAR), and use code"sd_app_event_wait()" in main function.

The advertising interval=1s, timeout=60s minimum connect interval=1.5s, maximum connect interval=2s, slave latency=0, connection supervisory timeout=6s

The results is,when advertising, idle consumption is about 10uA, but when connect, consumption is 1mA.

Why connect consumption so high? where can I config?

[Daniel.Chiu]

No~how can I verify it? I use PCA10000 dongle&MCP to connect. I also try to run on EK board, got the same results....

[kaku]

Dear Daniel It is strange..., how did you measure power consumption on your board or EK ? For example, ble_app_hrs is blinking LED during advertising, then connected with peer device, LED is always lighting. So LED consumes much more current... If so, how about disables LED port on your board ? Thanks.

[Daniel.Chiu]

I already disable all unneeded peripheral, no led, no uart, no i2c...etc, just maintain BLE needed.
and I also use same code to config "ble_app_hrs",disable button event, they all got same results, adv consumption is uA, connecting consumption=1mA, I notice when I change connect interval value(min=7.5ms to max=4s), the consumption does not change, I guess it's a issue.

[kaku]

According to S110 Softdevice Specification, power profile diagram both advertising and connecting is almost same during idle, but when advertising is about 10uA, the other hand connecting is 1mA. So I think, nRF51 hardware-wise is probably no problem... How about you raising your isisue on Nordic support case ?

[Stefan Birnir Sverrisson]

Hi Daniel

I suspect from your discussion with Kaku that the connection parameters have not been updated yet. If you change the connection interval and do not see a change in current consumpiton, then that must be the case. The central device will however set the connection interval when initially connected. If you connect with MCP from a windows PC, then the default connection interval is 20ms which will give you high current consumption. To understand the connection parameter update process, look at this thread. Also, to know the actual connection interval, look at this thread.

This thread will tell you more about 32kHz RC settings for lowest current consumption.

I also aggree with Kaku that you should have a development/evaluation kit to measure the current consumption of your firmware. If you get the same current consumption on your development/evaluation kit, then you know it is not an hardware issue on your custom board, then it is a firmware issue.