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sensors: aht20: Add AHT20 temperature humidity sensor
Add support of AHT20 Temperature and Humidity Sensor Signed-off-by: Rafael Lee <[email protected]>
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‎drivers/sensor/CMakeLists.txt

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@@ -4,6 +4,7 @@ add_subdirectory_ifdef(CONFIG_ADT7420 adt7420)
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add_subdirectory_ifdef(CONFIG_ADXL345 adxl345)
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add_subdirectory_ifdef(CONFIG_ADXL362 adxl362)
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add_subdirectory_ifdef(CONFIG_ADXL372 adxl372)
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add_subdirectory_ifdef(CONFIG_AHT20 aht20)
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add_subdirectory_ifdef(CONFIG_AK8975 ak8975)
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add_subdirectory_ifdef(CONFIG_AMG88XX amg88xx)
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add_subdirectory_ifdef(CONFIG_AMS_IAQ_CORE ams_iAQcore)

‎drivers/sensor/Kconfig

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@@ -49,6 +49,8 @@ source "drivers/sensor/adxl362/Kconfig"
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source "drivers/sensor/adxl372/Kconfig"
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source "drivers/sensor/aht20/Kconfig"
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source "drivers/sensor/ak8975/Kconfig"
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source "drivers/sensor/amg88xx/Kconfig"

‎drivers/sensor/aht20/CMakeLists.txt

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# SPDX-License-Identifier: Apache-2.0
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zephyr_library()
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zephyr_library_sources(aht20.c)

‎drivers/sensor/aht20/Kconfig

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# Copyright (c) 2022 Rafael Lee
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# SPDX-License-Identifier: Apache-2.0
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config AHT20
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bool "AHT20 Temperature and Humidity Sensor"
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default y
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depends on DT_HAS_ASAIR_AHT20_ENABLED
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select I2C
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help
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Enable driver for the AHT20 temperature and humidity sensor.

‎drivers/sensor/aht20/aht20.c

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/*
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* Copyright (c) 2022 Rafael Lee <[email protected]>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define DT_DRV_COMPAT asair_aht20
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#include <zephyr/device.h>
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#include <zephyr/drivers/i2c.h>
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#include <zephyr/drivers/sensor.h>
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#include <zephyr/kernel.h>
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#include <zephyr/logging/log.h>
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#include <zephyr/sys/byteorder.h>
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#include <zephyr/sys/crc.h>
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#define AHT20_STATUS_LENGTH 1
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#define AHT20_TOTAL_READ_LENGTH 7
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#define AHT20_CRC_POLY 0x31 /* polynomial 1 + x^4 + x^5 + x^8 */
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#define AHT20_CRC_INIT 0xff
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#define AHT20_CMD_RESET 0xBA
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#define AHT20_CMD_TRIGGER_MEASURE 0xAC
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#define AHT20_TRIGGER_MEASURE_BYTE_0 0x33
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#define AHT20_TRIGGER_MEASURE_BYTE_1 0x00
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#define AHT20_CMD_GET_STATUS 0x71
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#define AHT20_CMD_INITIALIZE 0xBE
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#define AHT20_FULL_RANGE_BITS 20
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#define AHT20_TEMPERATURE_RANGE 200
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#define AHT20_TEMPERATURE_OFFSET 50.0
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typedef union {
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struct {
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uint8_t: 3; /* bit [0:2] reserved */
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uint8_t calibrated: 1; /* bit [3] calibrated */
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uint8_t: 1; /* bit [4] reserved */
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uint8_t: 2; /* bit [5:6], AHT20 datasheet v1.1 removed 2 mode bits */
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uint8_t busy: 1; /* bit [7] reserved */
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};
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uint8_t all;
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} __attribute__((__packed__)) aht20_status;
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struct aht20_data {
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struct i2c_dt_spec bus;
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uint32_t humidity;
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uint32_t temperature;
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};
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LOG_MODULE_REGISTER(AHT20, CONFIG_SENSOR_LOG_LEVEL);
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static int aht20_channel_get(const struct device *dev, enum sensor_channel chan,
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struct sensor_value *val)
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{
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struct aht20_data *drv_data = dev->data;
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float temperature;
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switch (chan) {
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case SENSOR_CHAN_HUMIDITY:
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val->val1 = 0;
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val->val2 = (drv_data->humidity) * 1000000LL / (1 << AHT20_FULL_RANGE_BITS);
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break;
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case SENSOR_CHAN_AMBIENT_TEMP:
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temperature = (float)drv_data->temperature / (1 << AHT20_FULL_RANGE_BITS) *
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AHT20_TEMPERATURE_RANGE -
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AHT20_TEMPERATURE_OFFSET;
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val->val1 = (int32_t)temperature;
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val->val2 = (temperature - val->val1) * 1000000LL;
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break;
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default:
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return -ENOTSUP;
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}
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return 0;
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}
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static int aht20_init(const struct device *dev)
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{
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struct aht20_data *drv_data = dev->data;
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aht20_status sensor_status = {0};
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uint8_t const inquire_status_seq[] = {AHT20_CMD_GET_STATUS};
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uint8_t const initialize_seq[] = {AHT20_CMD_INITIALIZE};
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int ret = 0;
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k_sleep(K_MSEC(40)); /* wait for 40ms */
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ret = i2c_write_read_dt(&drv_data->bus, inquire_status_seq, sizeof(inquire_status_seq),
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&sensor_status.all, AHT20_STATUS_LENGTH);
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if (ret) {
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LOG_ERR("Inquire status failed");
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} else {
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LOG_INF("Inquire status successfully");
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}
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if (!sensor_status.calibrated) {
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LOG_INF("Calibrated bit is 0, need initialization");
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ret = i2c_write_dt(&drv_data->bus, initialize_seq, sizeof(initialize_seq));
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if (ret) {
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LOG_ERR("Initialization filaed");
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} else {
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LOG_INF("Initialization successful");
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}
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k_sleep(K_MSEC(10));
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}
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return ret;
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}
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static int aht20_sample_fetch(const struct device *dev, enum sensor_channel chan)
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{
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uint8_t tx_buf[] = {AHT20_CMD_TRIGGER_MEASURE, AHT20_TRIGGER_MEASURE_BYTE_0,
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AHT20_TRIGGER_MEASURE_BYTE_1};
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uint8_t rx_buf[AHT20_TOTAL_READ_LENGTH] = {0};
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aht20_status sensor_status = {0};
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struct aht20_data *drv_data = dev->data;
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int rc = 0;
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__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL || chan == SENSOR_CHAN_AMBIENT_TEMP ||
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chan == SENSOR_CHAN_HUMIDITY);
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rc = i2c_write_dt(&drv_data->bus, tx_buf, sizeof(tx_buf));
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if (rc < 0) {
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LOG_ERR("I2C write failed");
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return -EIO;
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}
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/* tested with AHT20, 40ms is enough for measuring, datasheet said wait 80ms */
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k_sleep(K_MSEC(40));
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while (1) {
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rc = i2c_read_dt(&drv_data->bus, rx_buf, AHT20_TOTAL_READ_LENGTH);
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if (rc < 0) {
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LOG_ERR("I2C read failed");
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return -EIO;
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}
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sensor_status.all = rx_buf[0];
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if (sensor_status.busy) {
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k_sleep(K_MSEC(5));
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} else {
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break;
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}
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}
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/* the read 7 bytes contains the following data: */
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/* status: 8 bits */
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/* humidity: 20 bits */
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/* temperature: 20 bits */
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/* crc8: 8 bits */
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drv_data->humidity = sys_get_be24(rx_buf + 1);
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drv_data->humidity >>= 24 - AHT20_FULL_RANGE_BITS;
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drv_data->temperature = sys_get_be24(rx_buf + 3);
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drv_data->temperature &= (1L << AHT20_FULL_RANGE_BITS) - 1;
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uint8_t crc =
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crc8(rx_buf, AHT20_TOTAL_READ_LENGTH - 1, AHT20_CRC_POLY, AHT20_CRC_INIT, false);
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if (crc != rx_buf[AHT20_TOTAL_READ_LENGTH - 1]) {
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LOG_ERR("CRC error");
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return -EIO;
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}
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return 0;
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}
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static const struct sensor_driver_api aht20_driver_api = {
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.sample_fetch = aht20_sample_fetch,
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.channel_get = aht20_channel_get,
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};
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#define AHT20_INIT(n) \
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static struct aht20_data aht20_data_##n = { \
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.bus = I2C_DT_SPEC_INST_GET(n), \
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}; \
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SENSOR_DEVICE_DT_INST_DEFINE(n, &aht20_init, NULL, &aht20_data_##n, NULL, POST_KERNEL, \
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CONFIG_SENSOR_INIT_PRIORITY, &aht20_driver_api);
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DT_INST_FOREACH_STATUS_OKAY(AHT20_INIT)

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