nRF 52832 power consumption SAADC/PPI/TIMER

[NORDIC_SUR]

Hi everybody

I have a couple of questions regarding power consumption for the 'nRF5_SDK_11.0.0_89a8197' (nRF52832).

I currently have an application which use 12-bit SAADC,The ADC model is timer+ppi+ADC.

I use a DC analyzer to measure the power.

1.when I not init SAADC,the power only 30 uA.(timer,ppi,saadc all not init)

2.when I init SAADC,the power is 2.3mA.(init timer,ppi,saadc)

3.when I stop SAADC,the power is 2.1mA.(stop timer,ppi,saadc)

question:

I can't find the differentce current between phase1 and phase3 (0.3mA and 2.1mA).What could be the reason for the difference in current of 1.8mA?

the ADC init code

void ADC_init(void)
{
		saadc_sampling_event_init();
		saadc_init();	
		saadc_sampling_event_enable();
}

the ADC uinit code

void ADC_uinit(void)
{
	nrf_drv_timer_disable(&m_timer);
	nrf_drv_timer_uninit(&m_timer);
	nrf_drv_ppi_uninit();
	
	nrf_saadc_task_trigger(NRF_SAADC_TASK_STOP);
	nrf_saadc_event_clear(NRF_SAADC_EVENT_STARTED);
	nrf_saadc_event_clear(NRF_SAADC_EVENT_END);
	nrf_saadc_disable();
}

[Øyvind]

Hello, 

I've replicated your issue, and can't find any solution. The problem seems to be that the SAADC does not completely disable.

If there is no reason for why you are using SDK 11, can you please try with e.g. SDKv15.3 instead? Go here to download: https://www.nordicsemi.com/Software-and-Tools/Software/nRF5-SDK/Download#infotabs

With newer SDK there is a low power setting which should turn the SAADC completely off.

Kind regards,
Oeyvind

[NORDIC_SUR]

thank you ,for you answer.I know the reson now.

ADC_init at first,and then must delay 1ms before ADC_uinit.

[Øyvind]

I tried that solution as well but was not successful. Can you show me how you solved this?

Thanks!

Kind regards,
Oeyvind

[NORDIC_SUR]

now I use the code like this:

void ADC_PWM_INIT(void)
{
	saadc_init();  //init adc
	nrf_saadc_enable();//enable adc
	saadc_sampling_event_init();
	saadc_sampling_event_enable();
}

init ADC at first.and then use start and stop funtion to control ADC.

void ADC_PWM_STOP(void)
{
	nrf_drv_timer_disable(&m_timer);
	nrf_saadc_task_trigger(NRF_SAADC_TASK_STOP);
	nrf_saadc_event_clear(NRF_SAADC_EVENT_STARTED);
	nrf_saadc_event_clear(NRF_SAADC_EVENT_END);
	nrf_saadc_disable();
}

void ADC_PWM_START(void)
{
	nrf_saadc_enable();
	nrf_saadc_task_trigger(NRF_SAADC_TASK_START);
	nrf_drv_timer_enable(&m_timer);
}

I found that  when stop ADC,it will have more 500uA if you don't disable the timer.

[Øyvind]

Good to hear you found the solution!
-Oeyvind