AHT20 Temperature and Humidity Sensor

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2c.h"

#define I2C_MASTER_NUM I2C_NUM_0         // I2C port number
#define I2C_MASTER_SDA_IO 21            // GPIO for SDA
#define I2C_MASTER_SCL_IO 22            // GPIO for SCL
#define I2C_MASTER_FREQ_HZ 100000       // I2C clock frequency
#define AHT20_ADDR 0x38                 // I2C address of the AHT20 sensor
#define AHT20_CMD_TRIGGER 0xAC          // Command to trigger measurement
#define AHT20_CMD_SOFTRESET 0xBA        // Command to reset the sensor
#define AHT20_CMD_INIT 0xBE             // Command to initialize the sensor

// Function to initialize I2C
void i2c_master_init() {
    i2c_config_t conf = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = I2C_MASTER_SDA_IO,
        .scl_io_num = I2C_MASTER_SCL_IO,
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
        .master.clk_speed = I2C_MASTER_FREQ_HZ,
    };
    i2c_param_config(I2C_MASTER_NUM, &conf);
    i2c_driver_install(I2C_MASTER_NUM, conf.mode, 0, 0, 0);
}

// Function to write a command (with parameter bytes) to the AHT20
esp_err_t aht20_write_command(uint8_t cmd, uint8_t p1, uint8_t p2, bool with_params) {
    i2c_cmd_handle_t handle = i2c_cmd_link_create();
    i2c_master_start(handle);
    i2c_master_write_byte(handle, (AHT20_ADDR << 1) | I2C_MASTER_WRITE, true);
    i2c_master_write_byte(handle, cmd, true);
    if (with_params) {
        i2c_master_write_byte(handle, p1, true);
        i2c_master_write_byte(handle, p2, true);
    }
    i2c_master_stop(handle);
    esp_err_t ret = i2c_master_cmd_begin(I2C_MASTER_NUM, handle, pdMS_TO_TICKS(1000));
    i2c_cmd_link_delete(handle);
    return ret;
}

// Function to read data from the AHT20
esp_err_t aht20_read_data(uint8_t *data, size_t length) {
    i2c_cmd_handle_t handle = i2c_cmd_link_create();
    i2c_master_start(handle);
    i2c_master_write_byte(handle, (AHT20_ADDR << 1) | I2C_MASTER_READ, true);
    i2c_master_read(handle, data, length, I2C_MASTER_LAST_NACK);
    i2c_master_stop(handle);
    esp_err_t ret = i2c_master_cmd_begin(I2C_MASTER_NUM, handle, pdMS_TO_TICKS(1000));
    i2c_cmd_link_delete(handle);
    return ret;
}

// Function to reset and initialize the AHT20
void aht20_init() {
    aht20_write_command(AHT20_CMD_SOFTRESET, 0, 0, false);
    vTaskDelay(pdMS_TO_TICKS(20)); // Wait after reset
    aht20_write_command(AHT20_CMD_INIT, 0x08, 0x00, true); // Init requires parameters 0x08 0x00
    vTaskDelay(pdMS_TO_TICKS(20)); // Wait for initialization
}

// Function to get temperature and humidity
void aht20_get_temp_humidity(float *temperature, float *humidity) {
    uint8_t data[6];
    aht20_write_command(AHT20_CMD_TRIGGER, 0x33, 0x00, true); // Trigger requires parameters 0x33 0x00
    vTaskDelay(pdMS_TO_TICKS(80)); // Wait for the measurement

    if (aht20_read_data(data, 6) == ESP_OK) {
        uint32_t raw_humidity = ((data[1] << 16) | (data[2] << 8) | data[3]) >> 4;
        uint32_t raw_temperature = ((data[3] & 0x0F) << 16) | (data[4] << 8) | data[5];

        *humidity = ((float)raw_humidity / 1048576.0) * 100.0;
        *temperature = ((float)raw_temperature / 1048576.0) * 200.0 - 50.0;
    } else {
        *humidity = -1.0;
        *temperature = -1.0;
    }
}

// Main application
void app_main() {
    float temperature = 0.0, humidity = 0.0;

    i2c_master_init();
    aht20_init();

    while (1) {
        aht20_get_temp_humidity(&temperature, &humidity);
        printf("Temperature: %.2f C, Humidity: %.2f %%\n", temperature, humidity);
        vTaskDelay(pdMS_TO_TICKS(2000));
    }
}

i2c:
  sda: GPIO21
  scl: GPIO22

sensor:
  - platform: aht10
    variant: AHT20
    temperature:
      name: "Living Room Temperature"
    humidity:
      name: "Living Room Humidity"
    update_interval: 60s

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
lib_deps =
    adafruit/Adafruit AHTX0 @ ^2.0.5

#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_AHTX0.h>  // Correct library for AHT20

// Create an instance of the AHT20 sensor
Adafruit_AHTX0 aht;  // Use AHTX0 instead of AHT10

void setup() {
  // Initialize Serial Monitor
  Serial.begin(115200);
  Serial.println("AHT20 Sensor Example");

  // Initialize I2C communication
  if (!aht.begin()) {  // No parameter needed
    Serial.println("Failed to find AHT20 sensor! Check wiring.");
    while (1);
  }
  Serial.println("AHT20 sensor initialized.");
}

void loop() {
  // Get sensor data
  sensors_event_t humidity, temp;
  aht.getEvent(&humidity, &temp); // Retrieve sensor readings

  // Print temperature and humidity
  Serial.print("Temperature: ");
  Serial.print(temp.temperature);
  Serial.println(" °C");

  Serial.print("Humidity: ");
  Serial.print(humidity.relative_humidity);
  Serial.println(" %");

  // Delay between readings
  delay(2000);
}

# Requires driver: ahtx0.py from https://github.com/targetblank/micropython_ahtx0
# Copy it to the board: mpremote cp ahtx0.py :
import machine
import time
from ahtx0 import AHT20

# Initialize I2C
i2c = machine.I2C(0, scl=machine.Pin(22), sda=machine.Pin(21))

# Initialize AHT20 sensor
sensor = AHT20(i2c)

# Main loop
while True:
    try:
        # Read temperature and humidity
        temperature = sensor.temperature
        humidity = sensor.relative_humidity

        # Print readings
        print("Temperature: {:.2f} °C".format(temperature))
        print("Humidity: {:.2f} %".format(humidity))

        # Wait for 2 seconds
        time.sleep(2)
    except Exception as e:
        print("Error reading sensor:", e)
        time.sleep(2)