/*

 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 <Wire.h> // Verificar libreria Wire

// the commands needed for the SRF sensors:

#define sensorAddress 0x70  //Constantes hexadecimales de memoria predefinida

#define readInches 0x50  //Constantes hexadecimales de memoria predefinidas

// use these as alternatives if you want centimeters or microseconds:

#define readCentimeters 0x51 //Constantes hexadecimales de memoria predefinidas

#define readMicroseconds 0x52 //Constantes hexadecimales de memoria predefinidas

// this is the memory register in the sensor that contains the result:

#define resultRegister 0x02 //Constantes hexadecimales de memoria predefinida

void setup()

{

 // start the I2C bus

 Wire.begin(); // inicia el programa por medio de la conexion

 // open the serial port:

 Serial.begin(9600); //Comunicacion para mostrar resultados en pantalla

}

void loop()

{

 // send the command to read the result in inches:
 // sendCommand(sensorAddress, 0x02, 0x1F);  //Configura rango de medicion
 //sendCommand(sensorAddress, 0x01, 0x10); //Establece una ganancia
 sendCommand(sensorAddress, 0x00, 0x51); //Enviar al sensor un comando lectura centimetros  //0x00, 0x51

 // 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("Distancia: ");

 Serial.print(sensorReading);

 Serial.println(" Microsegundos");

 // wait before next reading:

 delay(70);

}

/*

 SendCommand() sends commands in the format that the SRF sensors expect

*/

void sendCommand (int address, int Register, int command) { //int Register

 
 // start I2C transmission:

 Wire.beginTransmission(address);

 // send command:

 Wire.send(Register); //Register

 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;

}

Arduino SRF02 SFR08 SFR10 sensor reader

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