SparkFun gator:UV Hookup Guide
Power and Connections
Check that your power and data connections are correct and that the power
VOUT switch is in the
ON position on the gator:bit (v2).
Make sure that if you are using a transparent cover over the sensor that it still passes UV light. More modern clear plastics and glass covers (especially for photo or documents) usually have a special UV coating to prevent pigment deterioration and yellowing of paper.