Svenska ElektronikForumet

Kod: Markera allt

void main( void)
{
   char i;
   unsigned long T1, t1, t2;
   unsigned long  k;
   TRISB.3 = 1;                      /* CCP1-pin is input            */
   initserial();
   delay10(10);                      /* 1 sek delay                  */

    T1CON = 0b00.11.0.0.0.1 ;        /*  prescal 1:8  */
    CCP1CON = 0b00.00.0101 ;  
    OPTION.7 =0;  
                      
while(1)
  {
       
/* Väntar på signal, sen mäter värdet */

    
    CCP1IF = 0 ;                     /* reset flag            */
    while (CCP1IF == 0 );            /* wait for capture      */
    t1  = CCPR1H*256;
    t1 += CCPR1L;
    CCP1IF = 0 ;                     /* reset flag            */
    while (CCP1IF == 0 );            /* wait for next capture */
    t2  = CCPR1H*256;
    t2 += CCPR1L;
                    

   delay10(50); 

/* Calculations  */
   
    T1 = t2 - t1;                    /* calculate period                 */
    k = 37520000/T1;                 /* calculate frequency              */
    
   
/* print variable           */
    unslongtoa(k);
    string_out1();
    putchar('\n'); 
        
  }
}

void initserial( void )            /* initialise serialcom port */
{
   SPEN = 1;
   BRGH = 1;                        /* Async high speed   */
   TXEN = 1;                        /* transmit enable    */
   SPBRG = 130 -1;                  /* 9600 Baud @ 20 MHz-clockfrequency */
   CREN = 1;                        /* Continuous receive */
   RX9  = 0;                        /* 8 bit reception    */
   TRISB.2 = 0;                     /* serial_out is output */  
   TRISB.1 = 1;                     /* serial_in is input   */  
}


bit putchar( char d_out )           /* sends one char */
{
   if(d_out == '\0') return 0;     /* refuse to send 0 "end of string" */
   while (!TXIF) ;                 /* wait until previus character transmitted   */
   TXREG = d_out;
   return 1;                       /* done */
}

/* If two (or more) char's are recieved, but not read, the reciever will be locked! */
/* To unlock the reciever, run function OverrunRecover()                            */

void OverrunRecover(void)
{  
   char trash;
   trash = RCREG;                 /* the two char's that locked the reciever  */
   trash = RCREG;                 /* are read and ignored                     */
   CREN = 0;                      /* the unlock procedure ...                 */
   CREN = 1;
}

void unslongtoa(unsigned long u16)
{
   char i,temp;
   RPM[4] = '\0';
   for (i = 3; ;i--)
      {
       temp = u16 % 10;
       temp += '0';
       RPM[i]=temp;
       if (i==0) break;
       u16 /= 10;
      }
}

void string_out1( void ) 
{
   char i;  
   for( i = 0; putchar( RPM[i] ); i++); 
 }
 
void delay10( char n)
/*
  Delays a multiple of 10 milliseconds using the TMR0 timer
  Clock : 4 MHz   => period T = 0.25 microseconds
  1 IS = 1 Instruction Cycle = 1 microsecond
  error: 0.16 percent. B Knudsen.
*/
{
    char i;

    OPTION = 7;
    do  {
        i = TMR0 + 39;              /* 256 microsec * 39 = 10 ms */
        while ( i != TMR0)
            ;
    } while ( --n > 0);  
}