Simple termometer / hygrometer using a 8x8 led matrix as display

Most termometers / hygrometers use some kind of LCD to display information, this one only uses a 8x8 led matrix.

There is nothing special on the hardware part. The sensor is a BME280 in a I2C breakout board and the led matrix is monted on a MAX7219 control board.

All is controled by a Arduino Nano but I'm sure that it's overkill, something much less powerfull could be used.

The only part of the project that might have some value (I'm rather proud of it) is the routine to display 2 chars + decimals on the matrix.