AHT20 with ESP32-C3-DevKitM-1

Wiring for the AHT20 temperature + humidity on the ESP32-C3-DevKitM-1 (ESP32-C3, 3.3 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

Check before you power it on

• Supply: 3.3 V from the 3V3 pin.
• I2C can use almost any pins on the ESP32-C3-DevKitM-1; 8 (SDA) and 9 (SCL) are the defaults. If the part is not found, the wires may be crossed: try Wire.begin with the two exchanged.

Test code (Arduino)

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  Wire.begin(8, 9);  // SDA = 8, SCL = 9
  Wire.beginTransmission(0x38);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "AHT20 temperature + humidity found at 0x38" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Arduino board: esp32:esp32:esp32c3. If uploading does not start, hold BOOT, press and release RST, then release BOOT.

Questions

Which ESP32-C3-DevKitM-1 pins do I use for the AHT20?

VIN → 3V3, GND → GND, SCL → 9, SDA → 8.

Does the AHT20 work with the ESP32-C3-DevKitM-1 at 3.3 V?

Yes: the AHT20 runs at 3.3-5 V and the ESP32-C3-DevKitM-1 uses 3.3 V signals, so no level shifting is needed.

What is the I2C address of the AHT20?

0x38. An I2C scan (BoardPilot does it for you) shows which one your module uses.

Full ESP32-C3-DevKitM-1 pinout · AHT20 temperature + humidity: all pins and data

The AHT20 on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Nano Arduino Uno R3 WeAct Black Pill STM32F411CE ESP32-S3-DevKitC-1 Nordic nRF52840 DK NUCLEO-F401RE Raspberry Pi Pico 2 Raspberry Pi Pico W Raspberry Pi Pico Teensy 4.1

Other parts on the ESP32-C3-DevKitM-1

BME280 BMP280 DHT22 DHT11 HC-SR04 SSD1306 OLED MPU6050 DS18B20 WS2812B LED strip SG90 servo Relay module HC-SR501 PIR LCD 1602 I2C INA219 VL53L0X BH1750 MAX30102 RC522 RFID NEO-6M GPS Capacitive soil moisture sensor ADS1115 TM1637 28BYJ-48 stepper L298N Potentiometer Push button LED Joystick module SD card module