AHT20 + BMP280 sensor board
AHT20 (temperature ±0.3 °C, humidity ±2 %) at 0x38 and BMP280 (pressure ±1 hPa, temperature ±1 °C) at 0x77 on one I²C bus · VDD 3.3–5 V · pull-ups on the board · now 29 °C, 62 %, 1009 hPa
Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Pins
- VDD
- SDA
- GND
- SCL
What it is
This purple board has two sensors on one I²C bus: an AHT20 for temperature and humidity at address 0x38, and a BMP280 for air pressure (and temperature) at address 0x77. An I²C scan shows both addresses. Pressure also gives altitude and the weather trend.
What to check before you buy or wire it
- Wiring: VDD, GND, SDA and SCL. The pull-ups are on the board.
- The BMP280 on this board is at 0x77, so use bmp.begin(0x77) or just bmp.begin(). Many tutorials use 0x76, which is for other BMP280 boards.
- Libraries: Adafruit_BMP280 for the pressure. For the AHT20, Adafruit_AHTX0 on an Uno; on the ESP32 in the lab, AHT20.h or AHTxx.h.
Common mistakes
- Calling bmp.begin(0x76) and getting "sensor not found".
- Mistaking the BMP280 for a BME280: the BMP280 has no humidity sensor. On this board the humidity comes from the AHT20.
Where it is used
Weather stations, altitude loggers, and indoor climate monitors that need temperature, humidity and pressure from one small board.