tests: drivers: dac: Add loopback test with ADC

# SPDX-License-Identifier: Apache-2.0

cmake_minimum_required(VERSION 3.13.1)

find_package(Zephyr HINTS $ENV{ZEPHYR_BASE})

project(dac_loopback)

FILE(GLOB app_sources src/*.c)

target_sources(app PRIVATE ${app_sources})

CONFIG_ZTEST=y

CONFIG_DAC=y

CONFIG_ADC=y

/*

 * Copyright (c) 2020 Libre Solar Technologies GmbH

 *

 * SPDX-License-Identifier: Apache-2.0

 */

/**

 * @addtogroup t_driver_dac

 * @{

 * @defgroup t_dac_loopback test_dac_loopback

 * @}

 */

#include <zephyr.h>

#include <ztest.h>

extern void test_dac_loopback(void);

void test_main(void)

{

	ztest_test_suite(dac_loopback_test,

			 ztest_unit_test(test_dac_loopback));

	ztest_run_test_suite(dac_loopback_test);

}

/*

 * Copyright (c) 2020 Libre Solar Technologies GmbH

 *

 * SPDX-License-Identifier: Apache-2.0

 */

/*

 * @addtogroup test_dac_loopback

 * @{

 * @defgroup t_dac_basic_loopback test_dac_loopback

 * @brief TestPurpose: read back DAC driver output with ADC

 * @}

 */

#include <drivers/dac.h>

#include <drivers/adc.h>

#include <zephyr.h>

#include <ztest.h>

/*

 * We need to define an ADC channel to read back the output generated by the

 * ADC. The two pins need to be connected with a jumper in order to pass the

 * test in actual hardware.

 *

 * ADC and DAC need to use the same reference voltage, as the test sampling

 * point is at half of the full scale voltage.

 */

#if defined(CONFIG_BOARD_NUCLEO_L073RZ)

/*

 * DAC output on PA4 (Arduino A2 pin of Nucleo board)

 * ADC input read from PA1 (Arduino A1 pin of Nucleo board)

 */

#define DAC_DEVICE_NAME		DT_LABEL(DT_ALIAS(dac1))

#define DAC_CHANNEL_ID		1

#define DAC_RESOLUTION		12

#define ADC_DEVICE_NAME		DT_LABEL(DT_ALIAS(adc1))

#define ADC_CHANNEL_ID		1

#define ADC_RESOLUTION		12

#define ADC_GAIN		ADC_GAIN_1

#define ADC_REFERENCE		ADC_REF_INTERNAL

#define ADC_ACQUISITION_TIME	ADC_ACQ_TIME_DEFAULT

#else

#error "Unsupported board."

#endif

static const struct dac_channel_cfg dac_ch_cfg = {

	.channel_id = DAC_CHANNEL_ID,

	.resolution = DAC_RESOLUTION

};

static const struct adc_channel_cfg adc_ch_cfg = {

	.gain             = ADC_GAIN,

	.reference        = ADC_REFERENCE,

	.acquisition_time = ADC_ACQUISITION_TIME,

	.channel_id       = ADC_CHANNEL_ID,

};

static struct device *init_dac(void)

{

	int ret;

	struct device *dac_dev = device_get_binding(DAC_DEVICE_NAME);

	zassert_not_null(dac_dev, "Cannot get DAC device");

	ret = dac_channel_setup(dac_dev, &dac_ch_cfg);

	zassert_equal(ret, 0,

		"Setting up of the first channel failed with code %d", ret);

	return dac_dev;

}

/* ADC necessary to read back the value from DAC */

static struct device *init_adc(void)

{

	int ret;

	struct device *adc_dev = device_get_binding(ADC_DEVICE_NAME);

	zassert_not_null(adc_dev, "Cannot get ADC device");

	ret = adc_channel_setup(adc_dev, &adc_ch_cfg);

	zassert_equal(ret, 0,

		"Setting up of the ADC channel failed with code %d", ret);

	return adc_dev;

}

/*

 * test_dac_loopback

 */

static int test_task_loopback(void)

{

	int ret;

	struct device *dac_dev = init_dac();

	struct device *adc_dev = init_adc();

	if (!dac_dev || !adc_dev) {

		return TC_FAIL;

	}

	/* write a value of half the full scale resolution */

	ret = dac_write_value(dac_dev, DAC_CHANNEL_ID,

		(1U << DAC_RESOLUTION) / 2);

	zassert_equal(ret, 0, "dac_write_value() failed with code %d", ret);

	/* wait to let DAC output settle */

	k_sleep(K_MSEC(10));

	static s16_t m_sample_buffer[1];

	static const struct adc_sequence sequence = {

		.channels    = BIT(ADC_CHANNEL_ID),

		.buffer      = m_sample_buffer,

		.buffer_size = sizeof(m_sample_buffer),

		.resolution  = ADC_RESOLUTION,

	};

	ret = adc_read(adc_dev, &sequence);

	zassert_equal(ret, 0, "adc_read() failed with code %d", ret);

	zassert_within(m_sample_buffer[0],

		(1U << ADC_RESOLUTION) / 2, 32,

		"Value %d read from ADC does not match expected range.",

		m_sample_buffer[0]);

	return TC_PASS;

}

void test_dac_loopback(void)

{

	zassert_true(test_task_loopback() == TC_PASS, NULL);

}

common:

  tags: dac drivers userspace

tests:

  drivers.dac:

    platform_whitelist: nucleo_l073rz

    depends_on: dac