Color sensing (as well as detecting empty spaces) settled on IR-based sensors commonly used in line-following robots. You can watch the clock in action in the video embedded below just under the ...

However, the Arduino remains the recommended platform ... you're specifically working with analog components, such as IR ...

But [romain] doesn’t have to watch and wait for the info they want. Thanks to an IR proximity sensor, [romain] can interrupt the cycle and get the date, time, temperature, or even a smiley ...