TCS3200カラーセンサー

This sensor works. Don't expect it to be a super-accurate sensor. You select one color (R, G, or B) or white and it gives you back a value corresponding to the amount of that light hitting the sensor. You can cycle through the different colors fairly quickly if you want to read R, G, and B separately. Some other sensors have a bezel around the sensor to block side light, and on this sensor it's notably missing.