Build a Sunburn Alarm

Step 7 Make it: UI and Sensor

Add the buttons, as shown on the schematic.  You'll need 4 buttons;

1. Left
2. Right
3. Enter
4. Begin Exposure

If you edit the code, you can get away with less, although it's nice to have the additional inputs.  I've breadboarded 2 buttons below.

Also add the LED and cap.  This is your UV sensor portion of the circuit.  The longer lead on the LED goes to the negative rail, the shorter lead connects to P7.