Hardware
Current hardware setup, includes support for (total cost about 22€):
- Wemos Lolin32 OLED Board and clones (ESP-WROOM-32).
- MH-Z19B CO2 Sensor (0-5000ppm +/-50ppm range).
- KY-012 Buzzer module (needs an additional 2N7000 N-MOSFET or similar to activate).
As the ESP module is able to run supplied from standard USB Smartphone charger, it is only need to wire 4 cables between ESP module and MH-Z19B Sensor:
| ESP module | MH-Z19B Sensor |
|---|---|
| 5V | Vin |
| GND | GND |
| PIN 25 | Tx |
| PIN 26 | Rx |
Buzzer is connected through a 2N7000 N-Channel MOSFET (or similar) in order to provide +5V voltage for activation.
| ESP module | KY-012 + N-MOSFET |
|---|---|
| 5V | S |
| GND | GND - SOURCE |
| PIN 16 | Buzzer Control - GATE |
Note that this is an optional feature that can be disabled removing -DBUZZER_MODULE=1 on build_flags section from platformio.ini file.
- Aliexpress searching for ESP32 ESP-WROOM-32 OLED.
- Aliexpress searching for MH-Z19B
- Aliexpress searching for KY-012
MIT License.
