- This is a project for ESP32 with SSD1306 OLED modules(Heltec WIFI_KIT_32).
- MH-Z19B(CO2 sensor) is required to build this whole project. (get it from ebay or amazon. it's approximately US$20.)
- MH-Z19B can be connected to micro controller in two ways, "PWM" or "Serial". I chose "Serial".
| IO pin | Selected feature |
|---|---|
| IO16 | U2_RXD (* OLED reset pin is overridden with U2_RXD) |
| IO17 | U2_TXD |
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Add esp32 tool chain to your Arduino IDE. github.com/espressif/arduino-esp32
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Add "Adafruit-GFX-Library" to your libraries folder. github.com/adafruit/Adafruit-GFX-Library
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Add "Adafruit_SSD1306" to your libraries folder. github.com/adafruit/Adafruit_SSD1306
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Due to the nature of Adafruit library, you need to do the following:
- change the value of "SSD1306_LCDHEIGHT" to 64 so that it fits the display dimensions. To do this, simply uncomment "#define SSD1306_128_64" in stead of "#define SSD1306_128_32" in Adafruit_SSD1306.h:Line74-75
- change "Wire.begin()" to "Wire.begin(4,15)" in Adafruit_SSD1306.cpp:Line206
- The ESP32 board has a cheap/low-quality Chinese chip(CH341). This chip cannot go beyond 115200bps.
- IO pins for Serial1 is not available. Serial2 is the only available option to communicate with MH-19B for this board.