// I2C SRF10 or SRF08 Devantech Ultrasonic Ranger Finder 
// by Nicholas Zambetti <http://www.zambetti.com> 
// and James Tichenor <http://www.jamestichenor.net> 

#include <TwoWire.h> 
 
void setup() 
{ 
  Wire.begin();                // join i2c bus (address optional for master) 
  Serial.begin(9600);          // start serial communication at 9600bps 
} 
 
int reading = 0; 
 
void loop() 
{ 
  // step 1: instruct sensor to read echoes 
  Wire.beginTransmission(112); // transmit to device #112 (0x70) 
                               // the address specified in the datasheet is 224 (0xE0) 
                               // but i2c adressing uses the high 7 bits so it's 112 
  Wire.send(0x00);             // sets register pointer to the command register (0x00)  
  Wire.send(0x50);             // command sensor to measure in "inches" (0x50) 
                               // use 0x51 for centimeters 
                               // use 0x52 for ping microseconds 
  Wire.endTransmission();      // stop transmitting 
 
  // step 2: wait for readings to happen 
  delay(70);                   // datasheet suggests at least 65 milliseconds 
 
  // step 3: instruct sensor to return a particular echo reading 
  Wire.beginTransmission(112); // transmit to device #112 
  Wire.send(0x02);             // sets register pointer to echo #1 register (0x02) 
  Wire.endTransmission();      // stop transmitting 
 
  // step 4: request reading from sensor 
  Wire.requestFrom(112, 2);    // request 2 bytes from slave device #112 
 
  // step 5: receive reading from sensor 
  if(2 <= Wire.available())    // if two bytes were received 
  { 
    reading = Wire.receive();  // receive high byte (overwrites previous reading) 
    reading = reading << 8;    // shift high byte to be high 8 bits 
    reading |= Wire.receive(); // receive low byte as lower 8 bits 
    Serial.println(reading);   // print the reading 
  } 
 
  delay(250);                  // wait a bit since people have to read the output :) 
} 
 
 
/* 
 
// The following code changes the address of a Devantech Ultrasonic Range Finder (SRF10 or SRF08) 
// usage: changeAddress(0x70, 0xE6); 
 
void changeAddress(byte oldAddress, byte newAddress) 
{ 
  Wire.beginTransmission(oldAddress); 
  Wire.send(0x00); 
  Wire.send(0xA0); 
  Wire.endTransmission(); 
 
  Wire.beginTransmission(oldAddress); 
  Wire.send(0x00); 
  Wire.send(0xAA); 
  Wire.endTransmission(); 
 
  Wire.beginTransmission(oldAddress); 
  Wire.send(0x00); 
  Wire.send(0xA5); 
  Wire.endTransmission(); 
 
  Wire.beginTransmission(oldAddress); 
  Wire.send(0x00); 
  Wire.send(newAddress); 
  Wire.endTransmission(); 
} 
 
*/