Let's begin by exploring the DHT22 sensor module. This module can sense temperature and humidity. In general, the DHT22 has four pins. You can see the sensor pinout in Figure 2-3:
Figure 2-3: A general pinout for a DHT22 sensor module
For our demo, we need to wire the hardware as follows:
- Connect DHT22 pin 1 to the ESP32 board 3.3V.
- Connect DHT22 pin 2 to the ESP32 board GPIO 26 (IO26). You can add a pull resistor 4K7 (optional).
- Connect DHT22 pin 4 to the ESP32 board GND. You can add a pull resistor 4K7 (optional).
You can see my hardware wiring with the ESP-WROVER-KIT board and DHT22 in Figure 2-4:
Figure 2-4: A wiring sample from my hardware
Now that we have covered hardware wiring, let's move on to writing the program.