It should come as no surprise your optical mouse contains a very tiny, very low resolution camera. [Franci] decided to take apart one of his old mice and turn that tiny optical sensor into a webcam.
Inside [Franci]‘s Logitech RX 250 is an ADNS-5020 optical sensor. This three wire SPI device stuffed into an 8-pin package is a 15×15 pixel grayscale image sensor. [Franci] started this project by bringing out the Arduino and Ethernet shield. After soldering a pull-up resistor to the image sensor’s reset pin, connecting the rest of the circuit was as simple as soldering a few wires to the Arduino.
Video of the mousewebcam in action below.