srf08.ino

#include <Wire.h>

#define DEVICE 112

unsigned long range = 0;

void setup() {
  Wire.begin();                // join i2c bus (address optional for master)
  Serial.begin(115200);          // start serial communication at 9600bps
  for (int i = 1; i <= 15; i++) {
    changeAddress(112 + i, byte(0xE0));
  }
  Serial.println("Address: " + String(DEVICE));
  range = setRange(6000);
  Serial.println("Range: " + String(range) + "mm " + String(range*65/11008) + "ms");
}

int reading = 0;

void loop() {
  // step 1: instruct sensor to read echoes
  Wire.beginTransmission(DEVICE); // 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.write(byte(0x00));      // sets register pointer to the command register (0x00)
  Wire.write(byte(0x51));      // 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(DEVICE); // transmit to device #112
  Wire.write(byte(0x02));      // sets register pointer to echo #1 register (0x02)
  Wire.endTransmission();      // stop transmitting

  // step 4: request reading from sensor
  Wire.requestFrom(DEVICE, 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.read();  // receive high byte (overwrites previous reading)
    reading = reading << 8;    // shift high byte to be high 8 bits
    reading |= Wire.read(); // 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.write(byte(0x00));
  Wire.write(byte(0xA0));
  Wire.endTransmission();

  Wire.beginTransmission(oldAddress);
  Wire.write(byte(0x00));
  Wire.write(byte(0xAA));
  Wire.endTransmission();

  Wire.beginTransmission(oldAddress);
  Wire.write(byte(0x00));
  Wire.write(byte(0xA5));
  Wire.endTransmission();

  Wire.beginTransmission(oldAddress);
  Wire.write(byte(0x00));
  Wire.write(newAddress);
  Wire.endTransmission();
}

unsigned long setRange(int millimeter) {
  byte range;
  range = ceil(1.0 * constrain(millimeter, 43, 11008) / 43) - 1;
  Wire.beginTransmission(DEVICE);
  Wire.write(byte(0x02));
  Wire.write(range);
  Wire.endTransmission();
  return (range+1)*43;
}