sensor fluxo

   //code by Crenn from http://thebestcasescenario.com
    //project by Charles Gantt from http://themakersworkbench.com
    //To disable interrupts: cli(); disable global interrupts and
    //to enable them: sei(); enable interrupts

    //Varibles used for calculations
    int NbTopsFan; int Calc;

    //The pin location of the sensor
    int hallsensor = 2; typedef struct{

    //Defines the structure for multiple fans and
    //their dividers
    char fantype;
    unsigned int fandiv; }fanspec;

    //Definitions of the fans
    //This is the varible used to select the fan and it's divider,
    //set 1 for unipole hall effect sensor
    //and 2 for bipole hall effect sensor
    fanspec fanspace[3]={{0,1},{1,2},{2,8}}; char fan = 1;

    void rpm ()
    //This is the function that the interupt calls
    { NbTopsFan++; }

    //This is the setup function where the serial port is initialised,
    //and the interrupt is attached
    void setup()
    { pinMode(hallsensor, INPUT);
    Serial.begin(9600);
    attachInterrupt(0, rpm, RISING); }

    void loop ()
    //Set NbTops to 0 ready for calculations
    { NbTopsFan = 0;

    //Enables interrupts
    sei();

    //Wait 1 second
    delay (1000);

    //Disable interrupts
    cli();

    //Times NbTopsFan (which is apprioxiamately the fequency the fan
    //is spinning at) by 60 seconds before dividing by the fan's divider
    Calc = ((NbTopsFan * 60)/fanspace[fan].fandiv);

    //Prints the number calculated above
    Serial.print (Calc, DEC);

    //Prints " rpm" and a new line
    Serial.print (" rpm\r\n");
    }