How to check SAADC is enabled?

RE: How to check SAADC is enabled?

Jørgen Holmefjord — Fri, 27 Oct 2017 07:52:09 GMT

Yes, if you do not have a very high sample rate, you can save power by disabling the SAADC peripheral between samples. The end of the SAADC handler would then be the logical place to uninit the SAADC.

RE: How to check SAADC is enabled?

ndarkness — Thu, 26 Oct 2017 12:53:28 GMT

Ok, then I am using the right function since I am using the softdevice. Regarding to disabling the SAADC on the SAADC handler is that a good approach?

RE: How to check SAADC is enabled?

Jørgen Holmefjord — Thu, 26 Oct 2017 12:50:11 GMT

If you are using the softdevice, you need to use the softdevice API to enter sleep mode. WFE/SEV can only be used when the softdevice is disabled.

RE: How to check SAADC is enabled?

ndarkness — Thu, 26 Oct 2017 12:49:56 GMT

Another question, I am uninitialize my saadc at the end of the saadc handler function, is that correct?

RE: How to check SAADC is enabled?

ndarkness — Thu, 26 Oct 2017 12:46:37 GMT

@Jorgen thanks again, I have implemented so. I was wondering, in the power_manager function, I see that you set everything to go to sleep. I have taken that function from the heart rate example and there the calls to WFE,SEV are not present, should I set them too?

RE: How to check SAADC is enabled?

Jørgen Holmefjord — Thu, 26 Oct 2017 12:01:26 GMT

That depends on if you have uninited the SAADC. I suggest you use a flag to know when you have inited/uninited the SAADC, like this:

static uint8_t saadc_is_initialized = false;

uint32_t initialize_saadc()
{
	uint32_t err_code;
	err_code = nrf_drv_saadc_init();
	if(err_code != NRF_SUCCESS)
	{
		return err_code;
	}
	err_code = nrf_drv_saadc_buffer_convert();
	if(err_code != NRF_SUCCESS)
	{
		return err_code;
	}
	saadc_is_initialized = true;
	return err_code;
}

void uninitialize_saadc()
{
	nrf_drv_saadc_uninit();
	saadc_is_initialized = false;
}

void battery_timer_handler()
{
	uint32_t err_code;
	
	if(!saadc_is_initialized)
	{
		err_code = initialize_saadc();
		APP_ERROR_CHECK(err_code);
	}
	
	err_code = nrf_drv_saadc_sample();
	APP_ERROR_CHECK(err_code);
}

void power_manager()
{
	if(saadc_is_initialized)
	{
		uninitialize_saadc();
	}
	
	// Go to sleep
	__WFE();
	__SEV();
	__WFE();
}

RE: How to check SAADC is enabled?

ndarkness — Thu, 26 Oct 2017 11:47:41 GMT

so if I have a handler for updating my battery level, should it contain an initalization of the Saadc? If the power_manager has put it to sleep?

RE: How to check SAADC is enabled?

Jørgen Holmefjord — Thu, 26 Oct 2017 11:22:15 GMT

The driver should handle this for you. You just need to keep track of when you have called nrf_drv_saadc_init and nrf_drv_saadc_buffer_convert, and when you have called nrf_drv_saadc_uninit. When the two first functions have been called, the SAADC is ready to sample. The IRQ handler in the driver will check and clear the event registers, and you might not be able to reliably read these registers from your application.

RE: How to check SAADC is enabled?

ndarkness — Thu, 26 Oct 2017 10:40:14 GMT

I want to check whether the SAADC is started or not, just that. My device goes to sleep and i need to sample the battery after its timout expires, so before sampling I want to check that the SAADC is up, othwerwise I will start it up.

RE: How to check SAADC is enabled?

Jørgen Holmefjord — Thu, 26 Oct 2017 10:34:40 GMT

Why are you trying to use nrf_saadc_event_check?

RE: How to check SAADC is enabled?

ndarkness — Thu, 26 Oct 2017 10:26:36 GMT

@Jorgen, if I do as told, I get an error too few arguments to function 'nrf_saadc_event_check' looking into nrf_saadc.h it expects an event as the proto states __STATIC_INLINE bool nrf_saadc_event_check(nrf_saadc_event_t saadc_event)

RE: How to check SAADC is enabled?

Jørgen Holmefjord — Tue, 24 Oct 2017 12:38:53 GMT

No, nrf_saadc_event_check() will do that. nrf_saadc_enable_check() will return the value of the ENABLE register.

RE: How to check SAADC is enabled?

ndarkness — Tue, 24 Oct 2017 10:55:23 GMT

But with this function I will pass an saadc event type which will be filled if the saadc is enabled right?

RE: How to check SAADC is enabled?

Jørgen Holmefjord — Mon, 23 Oct 2017 09:02:57 GMT

Hi,

You can check if the SAADC peripheral is enabled by calling the HAL function nrf_saadc_enable_check(), but from your question I'm not sure this is what you want.

If you call nrf_drv_saadc_uninit(), the SAADC driver will be uninitialized, and the peripheral will be disabled. If you try to sample after this, without calling nrf_drv_saadc_init(), you will get an error code.

Best regards,

Jørgen