Current Consumption of nRF52832

RE: Current Consumption of nRF52832

haakonsh — Tue, 10 Apr 2018 09:37:37 GMT

Oh! Then yes that is nominal.

RE: Current Consumption of nRF52832

arish — Tue, 10 Apr 2018 09:23:29 GMT

I never had trouble putting the chip to sleep. Just wanted to confirm that the idle current value I am observing is nominal.

RE: Current Consumption of nRF52832

haakonsh — Tue, 10 Apr 2018 09:13:29 GMT

Idle is not the same as sleep. 2.95mA for a cortex M4-F running at 64MHz is actually really low. The HFCLK clock tree and the power management system is contributing to the current consumption.

Have you manage to put the CPU to sleep yet?

RE: Current Consumption of nRF52832

arish — Mon, 09 Apr 2018 13:33:40 GMT

Are you saying it's quite normal to have 2.95 mA as the CPU idle current? What could be the clock source for the CPU when I am not enabling the HFCLK explicitly? Are there any other peripherals contributing to this current?

RE: Current Consumption of nRF52832

haakonsh — Mon, 09 Apr 2018 13:15:02 GMT

You should see 1.2µA after WFE-SEV-WFE (System ON). This case you referred to was an issue where the FPU unit did not turn off automatically when entering SystemON/OFF, the fix is to manually turn off the FPU before entering sleep. This is not the issue in your case.

2.95 mA is the CPU idling (infinite loop), this means that your device does not enter sleep.

RE: Current Consumption of nRF52832

arish — Mon, 09 Apr 2018 12:42:54 GMT

Hi Håkon,

Thank you for your prompt response. I am aware of the 'System ON' sleep mode you suggested and have been using it successfully :) I have also used the DCDC mode previously and have further reduced the CPU idling current to 2.95 mA. What I am interested in is the current consumed when the chip comes out of the sleep mode. I feel that even with DCDC enabled, 2.95 mA (idle current) is on the higher side with no softdevice programmed. I haven't worked with ARM Core M4 device before but saw an idle current of ~200 uA in one of the posts on this forum.

Just curious, shouldn't the System ON sleep code be the below:

#include "nrf.h"
#include <stdint.h>
#include <stdbool.h>
int main(void)
{
    NRF_POWER->DCDCEN = 1;  // Enable DCDC
    while(1)
    {
        __SEV();
        __WFE();
        __WFE();    // Puts the CPU to sleep
    }
}

Arish

RE: Current Consumption of nRF52832

haakonsh — Mon, 09 Apr 2018 11:47:22 GMT

Hey arish,

What you are measuring is the CPU idling and powered by LDO (see CPU performance). You can write the following to put the CPU to sleep and turn on the DCDC regulator (DCDC components must be available).

#include "nrf.h"
#include <stdint.h>
#include <stdbool.h>
int main(void)
{
    NRF_POWER->DCDCEN = 1;  // Enable DCDC
    while(1)
    {
        __WFE();
        __SEV();
        __WFE();    // Puts the CPU to sleep
    }
}

Cheers,

Håkon.