The USB Thermal Monitor is a very simple circuit combining a Arduino Pro Micro, AM2302 temperature and humidity sensor and a 0.91 Inch I2C SSD1306 OLED Display. It uses the built in USB serial connection on the Pro Micro to communicate with a host computer to allow logging of temperature and humidity data.

Serial Data Format

Every 2 seconds the current humidity and temperature is output on the serial port at 9600 baud. It is output as a string with the following format:

<fw ver>,<humidity %>,<temperature in Celsius>\n

Example Output:

1.0,43,22.5

Physical Display

I wanted to be able to view the temperature as well as log it so the circuit supports a simple i2c display. The display is updated every 2 seconds with the latest readings.

By default the firmware uses Fahrenheit for the display but that would be easily changed.