AHT20 temperature and humidity sensor

Defines

AHT_I2C_ADDRESS_GND

Device address when ADDR pin connected to GND.

AHT_I2C_ADDRESS_VCC

Device address when ADDR pin connected to VCC.

Enums

enum aht_type_t

Device types.

Values:

enumerator AHT_TYPE_AHT1x

AHT10, AHT15.

enumerator AHT_TYPE_AHT20

AHT20.

enum aht_mode_t

Device modes.

Deprecated:

The sensor modes are not supported by the driver: it always triggers a measurement in the command mode. The field is kept for the source compatibility only.

Values:

enumerator AHT_MODE_NORMAL

Normal mode.

enumerator AHT_MODE_CYCLE

Continuous measurements mode, not supported by the driver.

Functions

esp_err_t aht_init_desc(aht_t *dev, uint8_t addr, i2c_port_t port, gpio_num_t sda_gpio, gpio_num_t scl_gpio)

Initialize device descriptor.

Parameters:

dev – Device descriptor

addr – Device I2C address

port – I2C port

sda_gpio – SDA GPIO

scl_gpio – SCL GPIO

Returns:

ESP_OK on success

esp_err_t aht_free_desc(aht_t *dev)

Free device descriptor.

Parameters:

dev – Device descriptor

Returns:

ESP_OK on success

esp_err_t aht_init(aht_t *dev)

Init device.

Waits for the sensor to power up, sends the calibration command and checks the calibration bit. The command differs between the device types: 0xE1 for AHT10/AHT15 and 0xBE for AHT20.

Parameters:

dev – Device descriptor

Returns:

ESP_OK on success

ESP_ERR_INVALID_STATE if the sensor has not been calibrated

ESP_ERR_TIMEOUT if the sensor has not become idle

esp_err_t aht_reset(aht_t *dev)

Soft reset device.

Resets the sensor and initializes it again.

Parameters:

dev – Device descriptor

Returns:

ESP_OK on success

ESP_ERR_TIMEOUT if the sensor has not become idle

esp_err_t aht_get_status(aht_t *dev, bool *busy, bool *calibrated)

Get device status.

Parameters:

dev – Device descriptor

busy – [out] Busy flag

true: device currently measuring

false: device is idle

calibrated – [out] Calibration success flag

true: sensor calibrated

false: sensor not calibrated

Returns:

ESP_OK on success

esp_err_t aht_get_data(aht_t *dev, float *temperature, float *humidity)

Get temperature and relative humidity.

Triggers a measurement, waits for the sensor to finish it and reads the result. The output values are set only when ESP_OK is returned. For the AHT20 the frame contains a CRC-8 checksum, and a corrupted frame is rejected.

Parameters:

dev – Device descriptor

temperature – [out] Temperature, degrees Celsius

humidity – [out] Relative humidity, percents

Returns:

ESP_OK on success

ESP_ERR_TIMEOUT if the sensor has not finished the measurement

ESP_ERR_INVALID_STATE if the sensor is not calibrated

ESP_ERR_INVALID_RESPONSE if the AHT20 frame has a wrong CRC

struct aht_t

#include <aht.h>

Device descriptor.

Public Members

i2c_dev_t i2c_dev

aht_type_t type

aht_mode_t mode

Not used, see aht_mode_t.