Read one sample from ADC without timers.

RE: Read one sample from ADC without timers.

Rafael Barrero — Tue, 14 Jan 2020 14:04:05 GMT

Ok I retried and it works. My problem after your answer was that I defined an init function but I didn't call it. Thanks for all.

Best regards

RE: Read one sample from ADC without timers.

Jørgen Holmefjord — Tue, 14 Jan 2020 13:30:30 GMT

It is not possible to initialize the SAADC driver itself in blocking mode, hence a callback is required to handle the events when event-driven sampling is used. As you can see, the callback is blank and will not be called in this sample application. You could pass 'NULL' to the init function, but the driver will assert in debug mode if no callback is provided.

The change you proposed for using AIN4 is correct. I tested that this works with the code for P0.28.

RE: Read one sample from ADC without timers.

Rafael Barrero — Tue, 14 Jan 2020 13:05:32 GMT

Okay thanks, I'm trying to adapt to my code and see if works. I'm tryimg to understand your example and my biggest doubt is about "saadc_callback". Could you explain what purpose that function has?

As a complementary question, I want to use ADC throught P0.28(supposed to be Analog Input 4).. How result the code? I tried changing

nrf_saadc_channel_config_t channel_config = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);

nrf_saadc_channel_config_t channel_config =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN4);

but not work.

Thank you, best regards

RE: Read one sample from ADC without timers.

Jørgen Holmefjord — Tue, 14 Jan 2020 12:10:13 GMT

Hi,

The thread you linked is for the ADC in nRF51 series. It differs quite a bit from the SAADC in nRF52 series.

I have created a minimal blocking SAADC example in SDK 16.0.0 that you can use for reference:

devzone.nordicsemi.com/.../saadc_5F00_simple_5F00_blocking_5F00_sdk_5F00_16.0.0.zip

Note that the SAADC will always work in an event-driven way. The difference with blocking mode is that the function will busy loop inside the function until the sampling is done.

Best regards,
Jørgen