AHT20

Connects over

I²C

Address

0x38

Made by

Aosong

Datasheet

cdn-shop.adafruit.com

Use it

hardware {
    device aht20: AHT20
}

every 1s {
    let value: float = aht20.temperature()
    log("aht20", "temperature={value}")
}

On its own, the declaration puts the AHT20 on the first I²C bus (SDA 21, SCL 22 on the ESP32) at 0x38. To choose the pins or the address, declare the bus and attach the device: device aht20: AHT20 on i2c0 at 0x38 with i2c i2c0(sda: 21, scl: 22).

Methods

• aht20.temperature() -> float

  Temperature in °C

• aht20.humidity() -> float

  Relative humidity %

Wiring

Specifications

Voltage

2.2V – 5.5V

Current

23 μA measure, 0.25 μA sleep

Temp range

−40°C to +85°C ±0.3°C

Humidity range

0–100% RH ±2%

Interface speed

I²C up to 400 kHz

Tips

• Address is fixed at 0x38 — only one AHT20 per I²C bus without a multiplexer.
• Needs 40 ms after power-on before the first measurement.
• Replacement for the older AHT10 with better humidity accuracy.

Alternatives worth knowing:

• SHT31: Sensirion equivalent, slightly more accurate, costlier.
• BME280: Adds pressure on top of T/H if you need altitude.