power consumption is too high on my nrf52 SoC

[Juliusc]

Hi, 

I am currently trying to decrease my power output, for this purpose I used a power profiler and found this pattern:

I am using a test firmware that just disables all unused gpio ports, start ble and then goes into while(1){ __WFE();}

power consumption is never below 400uA, the spikes seem fine (BLE advertising spikes I presume).

s there anything you can tell me about why this would happen?

Even if I turn of BLE I still got 200uA on average, so some of the problem is probably in my configuration (but. already increased the adv intervals) and part of it is the chip by itself. I am using a custom PCB but am pulling down all GPIO ports

Best, Julius

[Vidar Berg]

Hi Julius,

Unused pins can be left floating without affecting the sleep current as GPIO pins are configured as inputs with the input buffer disconnect after reset. 

Are you developing with the nRF Connect SDK or the nRF5 SDK? 

Best regards,

Vidar

[Juliusc]

nRF5 SDK

I see I noticed that the current is a bit higher when I dont set certain gpio pins to clear specifically. 

[Juliusc]

yes, its 450uA on average if I turn on BLE (as seen in the image provided)

without BLE its 220 on average but as I said I want to focus on the BLE problem first. 

[Vidar Berg]

You should be able to see the sleep/floor current between advertising events (assuming the spikes are BLE events and not some other noise). 

Do you start an advertiser after you enable BLE? In that case, what interval are you advertising at? 

[Juliusc]

yeah exactly thats why i made this thread I never see like near 0 current or 'real' sleeping intervals its just always like this, my advertising interval is around 300ms 

the event where my arrow is pointing is supposed to be the advertising I think:

[Vidar Berg]

Are you able to share your main() function here?

[Juliusc]

int main(void) {

  gpio_init();

  ble_init();

  flash_init();

  ble_advertise();

  while (1) {
     __WFE();
  }

}

gpio_init as I said just initializes (clears) some pins, ble_init() does the usual initialization of services etc, in flash init I just read from flash so no further interefering processes from there, I also have no scheduler enabled. I also tried sd_app_evt_wait() but no difference here

[Vidar Berg]

There wasn't much to see in that function. Do you have a DK you can try this on? Alternatively, could you share your whole project here or in a private ticket so I can try it here?

[Juliusc]

this is what I get running the exact same code on a PCA10056 DK

[Vidar Berg]

You still have a high idle current, although it's much less noisy. Either way, I need to know what your code is doing to understand what's causing this.

[Juliusc]

I could try to trim it down, its basically only the ble file then anyways, I could send you the params Im using without the services

how do I know if WFE() actually works? I got the feeling it doesnt really shut down the uC.

[Vidar Berg]

The idle current would not have dropped below the CPU run current if the system did not enter sleep. The CPU run current ranges from approximately 2.8 mA to 6.3 mA depending on the supply and regulator configuration. There might be something that is either requesting system resources, such as the 16 MHz clock in sleep mode, or causing leakage from the IOs.

Do you measure a different sleep current if you comment out everything except the main loop in your main() function while running on the DK?