High current consumption System OFF mode

RE: High current consumption System OFF mode

TOCGRE — Mon, 10 Feb 2020 15:04:59 GMT

Hi,

At last I managed to measure 300nA (and a bit less I must say !) on the BLE651 module with your code

int main(void){
  NRF_POWER->SYSTEMOFF = 1;
  for(;;){}
}

I first tried to measure current consumption on the eval board PCA10040 to be sure that my measuring setup allowed me to measure a current as low as 300nA. It worked.

After that on my module I just dropped the breadboard as you suggested and soldered all the GND pins together.

Thank you for helping me !

RE: High current consumption System OFF mode

Simonr — Fri, 07 Feb 2020 12:36:29 GMT

Indeed, I don't think your equipment is the issue either by the description in your main post, but I wanted to include it just in case. Are you at all able to drop the breadboard when measuring, to see if the current draw drops at all, or do you have more than one of the BL651 modules, so you can check if the module you're using is faulty or not? There shouldn't be anything on the module itself drawing the extra current as far as I know, so it's either leaking through the breadboard or you've got a faulty chip (at least that's my bet).

Best regards,

Simon

RE: High current consumption System OFF mode

TOCGRE — Fri, 07 Feb 2020 09:12:17 GMT

Hi,

I tried your code:

#include <stdbool.h>
#include <stdint.h>
#include "nrf_soc.h"

int main(void)
{
  NRF_POWER->SYSTEMOFF = 1;
  for(;;){}
}

But I am still measuring 4.6uA or 4.7uA.

I managed to reach 3.8uA by defining NRF_LOG_ENABLED to 0 in the sdk_config.h

Do you think of some modules I should disable in the sdk_config.h to lower consumption ?

I am shure that my measurement equipment is accurate enough because it has a resolution of 10nA and I have already measured lower currents (~1uA) on other device.

There is no external something on the circuit. Only the BL651 module from Laird. Maybe the cause could come from inside the module on the components next to the nrf52810 but I doubt it since Laird Connectivity announces the same 0.3nA current consumption on SYSTEM OFF mode.

I think that maybe the fact that I am using a bread board and wires soldered to the module leads to increasing consumption. I cannot be sure that the weld quality is perfect or that contacts are really good in the breadboard. But I do not know if it could decrease the current of a value as big as 3uA.

Best regards,

RE: High current consumption System OFF mode

Simonr — Thu, 06 Feb 2020 10:28:14 GMT

Can you try running the following code? This should, per definition consume 0.3µA. If you're still measuring more than that in that case, then the chip is either faulty, or the current measurement is incorrect (either the measuring equipment is not accurate enough, or something external is drawing power).

int main(void){
  NRF_POWER->SYSTEMOFF = 1;
  for(;;){}
}

Best regards,

Simon

RE: High current consumption System OFF mode

TOCGRE — Wed, 05 Feb 2020 14:12:18 GMT

Hi,

Thank you for the fast reply !

So you mean that the device starts executing __WFE(); before it has time to enter SYSTEM OFF on the previous line ?

I tried to empty the while(1) block after the NRF_POWER->SYSTEMOFF = 1; line but I got the same consumption.

What I see in ble_app_hrs example is that the sleep_mode_enter() function is called in interrupt handlers. Can't I call it in the main() function ?

Best regards

RE: High current consumption System OFF mode

Simonr — Wed, 05 Feb 2020 11:56:46 GMT

In your code, it seems like you tell the device to go to system OFF mode, then immediately turn on to wait for an event. When using WFE(); the device will stay in system ON, waiting for an event to trigger it. You won't be able to wake the device from system OFF with an event, as the chip won't be on to detect one.

I suggest you take a look at, for example, the ble_app_hrs example which uses the sleep_mode_enter() function in order to go to system OFF mode.

Best regards,

Simon