ADC Config Invalid Value nRF Connect

[EthanDP]

Hello, I am using the nRF connect SDK and am currently running into some issues with using the on board ADC. My issue relates to the adc_channel_setup function which returns an error 22 (Invalid Argument). Despite this I can't find the source of this error. My config struct can be seen below as well as how I am getting the device:

#include <zephyr.h>
#include <device.h>
#include <drivers/gpio.h>
#include <drivers/adc.h>

#define ADC_DEVICE_NAME DT_LABEL(DT_ALIAS(adcctrl))
#define DEFAULT_ACQ_TIME ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 30)

static const struct device *adc_device;

static int16_t buffer[8];

const static struct adc_channel_cfg adc_config = {
	.gain = ADC_GAIN_1_6,
	.reference = ADC_REF_INTERNAL,
	.acquisition_time = DEFAULT_ACQ_TIME,
	.channel_id = 0,
	.differential = 0,
#if CONFIG_ADC_CONFIGURABLE_INPUTS
	.input_positive = 1, 
#endif
};

uint8_t adc_setup() {
    adc_device = device_get_binding(ADC_DEVICE_NAME);
    if (!adc_device) {
		printk("Failed to get ADC Device\n\r");
	}
    int8_t error_code = adc_channel_setup(adc_device, &adc_config);
    
    ...
}

For reference I am using an nRF52810 DK with the following config file:

CONFIG_I2C=y
CONFIG_ADC=y
CONFIG_ADC_ASYNC=y
CONFIG_SPI=y

Does anything stand out as to what may be going wrong/what I have entered that is incorrect?

[EthanDP]

I also forgot to include my device tree:

/ {
    aliases {
    	led0 = &led0;
    	bus-int = &bus_int;
    	i2c0 = &i2c0;
    	bootloader-led0 = &led0;
    	adcctrl = &adc;
    };
}

&adc {
	status = "okay";
};

[Håkon Alseth]

Hi,

 

Do you have "CONFIG_ADC_CONFIGURABLE_INPUTS" Y-selected at your end?

 

Kind regards,

Håkon

[EthanDP]

Hi Håkon,

It is enabled by default with the nRF52810 DK but I added that to my config as well and the issue still persists

[Håkon Alseth]

Hi,

 

You're ending up in the default switch case here:

https://github.com/nrfconnect/sdk-zephyr/blob/main/drivers/adc/adc_nrfx_saadc.c#L123-L126

 

This is because 30 is not a valid acquisition time. You should choose one of the defined ones in the TACQ field:

https://infocenter.nordicsemi.com/topic/ps_nrf52810/saadc.html?cp=4_5_0_5_16_10_19#register.CH-0-7.CONFIG

 

Kind regards,

Håkon