A coaster with LED light indictors that notifies waiters when you need service.
I used an FRS censor to create three thresholds that identify when a class in full, half drank or empty. Within the arduino code I used several “if else” statements that distinguish between the weight of the glass.
The FRS censors are calibrated to recognize three thresholds or weights. When the glass is full a red LED indicator turns red. When the glass is half full the LED indicator turns tell. This tells a waiter that you are ok and don’t need help. The final LED state turns green when the glass is near empty, indicating that you need a refill.