An error with NRF_SAADC_CHANNEL_COUNT define

[MStampe]

Hi

I am using the SDK 15.2.0 and developing for a NRF52832 using Segger.

I have a problem with the define NRF_SAADC_CHANNEL_COUNT in "nrf_saadc.h". It is set to 8.

The enum defining the channels e.g "NRF_SAADC_INPUT_AIN7" is defined as value 8. The "NRF_SAADC_INPUT_VDD" is defined with value 9.

The problem is that the asserts in nrfx_saadc.c is written as "channel < NRF_SAADC_CHANNEL_COUNT".

Am I looking wrong at this or is this a mistake in the driver?

Hope you can help

Best regards
Mikkel

[Edvin]

Hello,

The NRF_SAADC_CHANNEL_COUNT is not compared to the pin number in the channel config. It is compared to the channel, so this shouldn't be a problem.

Check out how it is set up in the examples\peripheral\saadc example:

    nrf_saadc_channel_config_t channel_config =
    NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);
    // this does:
    // channel_config.pin_p = NRF_SAADC_INPUT_AIN0;
        
    err_code = nrf_drv_saadc_init(NULL, saadc_callback);
    APP_ERROR_CHECK(err_code);

    // Init channel 0:
    err_code = nrf_drv_saadc_channel_init(0, &channel_config);
    APP_ERROR_CHECK(err_code);
    
    // nrf_drv_saadc_channel_init(ch, config)
    //it is "ch" that is compared with NRF_SAADC_CHANNEL_COUNT. ch should not contain your pin number.
    

So the channels you have to keep track of yourself. If you want to use NRF_SAADC_INPUT_VDD:

channel_config = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_VDD);

nrf_drv_saadc_channel_init(ch_num, &channel_config);

Now the pin number is stored in channel_config, but the channel number has to be a number between 0 and 7, since this is how many physical channels the ADC has.

Best regards,

Edvin

[MStampe]

Hi Edvin

Thank you for the answer. Ahh I do now understand.
So that the ch_num should just be any number between 0-7 that I keep track of myself.

I though that the AINx was the channel number, and that exceeded the 8 channels. So that was confusing.