SpeeDe V_03:
The aim of the third version of the SpeeDe is to improve the sensitivity to capture the speed of even smaller object. In this regard, I have done some modification in the program ( using the concept of interrupts in Arduino).
ARDUINO PROGRAM: // include the library code:
#include <LiquidCrystal.h>
// constants won’t change. They’re used here to
// set pin numbers:
// variables will change:
volatile int State = 0; // variable for reading the pushbutton status
// Start and stop times
volatile unsigned long start_time_us = 0;
volatile unsigned long stop_time_us = 0;
float delta_time;
float speed_var;
Reference: http://www.auraauro.com/uncategorized/speede-v-01-2/
http://arduino.cc/en/Reference/attachInterrupt