/*
 
 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;
 
}