HC-SR04, Ultrasonic, Distance Sensor+SainSmart LCD Keypad Shieldbrand: SainSmart SKU: 20-011-C23
The SainSmart LCD Keypad Shield includes a 16x2 HD44780 White on Blue LCD module and a 5 push button keypad for menu selection and user interface programming. Fully assembled. On-line Arduino tutorial and example code. Compatible with Arduino Uno, Mega, Duemilanove. Uses digital pins 4 - 10, and analog pin 0.
The Ultrasonic Module HC-SR04 Distance Sensor are 4 pins out of the module: VCC, Trig, Echo, GND. So it's a very easy interface for controller to use it ranging.
The all process is : pull the Trig pin to high level for more than 10us impulse, the module start ranging; finish ranging, If you find an object in front, Echo pin will be high level, and based on the different distance,it will take the different duration of high level. So we can calculated the distance easily:
Distance = ((Duration of high level)*(Sonic :340m/s))/2
1 SainSmart LCD Keypad Shield
1 Ultrasonic Module HC-SR04 Distance Sensor