This code reads a Devantech SRF02 ultrasonic ranger (and probably an SRF08 and SRF10 as well) It uses the Wire library for Wiring and Arduino.
/*
SRF02 sensor reader
language: Wiring/Arduino Reads data from a Devantech SRF02 ultrasonic sensor.
Should also work for the SRF08 and SRF10 sensors as well.
Sensor connections:
SDA - Analog pin 4
SCL - Analog pin 5
created 5 Mar. 2007
by Tom Igoe
*/
// include Wire library to read and write I2C commands:
#include
// the commands needed for the SRF sensors:
#define sensorAddress 0x70
#define readInches 0x50
// use these as alternatives if you want centimeters or microseconds:
#define readCentimeters 0x51
#define readMicroseconds 0x52
// this is the memory register in the sensor that contains the result:
#define resultRegister 0x02
void setup()
{
// start the I2C bus
Wire.begin();
// open the serial port:
Serial.begin(9600);
}
void loop()
{
// send the command to read the result in inches:
sendCommand(sensorAddress, readInches);
// wait at least 70 milliseconds for a result:
delay(70);
// set the register that you want to reas the result from:
setRegister(sensorAddress, resultRegister);
// read the result:
int sensorReading = readData(sensorAddress, 2);
// print it:
Serial.print("distance: ");
Serial.print(sensorReading);
Serial.println(" inches");
// wait before next reading:
delay(70);
}
/*
SendCommand() sends commands in the format that the SRF sensors expect
*/
void sendCommand (int address, int command) {
// start I2C transmission:
Wire.beginTransmission(address);
// send command:
Wire.send(0x00);
Wire.send(command);
// end I2C transmission:
Wire.endTransmission();
}
/*
setRegister() tells the SRF sensor to change the address pointer position
*/
void setRegister(int address, int thisRegister) {
// start I2C transmission:
Wire.beginTransmission(address);
// send address to read from:
Wire.send(thisRegister);
// end I2C transmission:
Wire.endTransmission();
}
/*
readData() returns a result from the SRF sensor
*/
int readData(int address, int numBytes) {
int result = 0; // the result is two bytes long
// send I2C request for data:
Wire.requestFrom(address, numBytes);
// wait for two bytes to return:
while (Wire.available() < 2 ) {
// wait for result
}
// read the two bytes, and combine them into one int:
result = Wire.receive() * 256;
result = result + Wire.receive();
// return the result:
return result;
}
