SMAKN Ultrasonic Module Hc-sr04 Distance Sensor for Arduino UNO Mega R3 Mega2560 Duemilanove Nano Robot Xbee Zigbee
Using IO trigger for at least 10us high level signalThe Module automatically sends eight 40 kHz and detect whether there is a pulse signal backIF the signal back, through high level ,time of high output IO duration is the time from sending ultrasonic to returning.Test distance = (high level time?velocity of sound (340M/S) /2Power supply :5V DC, quiescent current : <2mA,effectualangle: <15??ranging distance : 2cm~500 cm?resolution : 0.3 cm><BR>There 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))/2NOTE: The link is the documents about Ultrasonic Module HC-SR04 Distance Sensor.