Timer/counter operating Mode

/*  

*

*Frequency measurement

*Speed measurement

*/

#include "compiler.h"

#include "tc.h"

#include "gpio.h"

#include "TimerCont.h"

//Initialization of the function exact_geschwindigkeit

void exact_geschwindigkeit_init() 

{   //brief Configuration functionality on a pin.

    //Parameters when initializing a counter in capture mode.

    tc_capture_opt_t capture_opt=

    {

       .channel = TIMER_CONTR_TC_CHANNEL,  // channel selection

       .ldra =1,                           // rising edge of TIOA

       .ldrb =2,                           // falling edge of TIOA

       .etrgedg =0,                         // external Trigger Edge Selection none

       .cpctrg =1,                         // RC Compare has no effect on the counter and its clock

       .tcclks =1,                         // clock Selection Timer_clok 1

       .abetrg =1,                         // TIOA is used as an external trigger

       .ldbdis =false,                     // Counter clock disable with RB loading

       .ldbstop = false,                   // Counter clock stopped with RB loading

    }  ;

    //Sets options for counter capture initialization.

    tc_init_capture(TIMER_CONTR_TC, &capture_opt);

    //Starts a counter.

    volatile avr32_tc_t *tc=TIMER_CONTR_TC;

    tc_start(TIMER_CONTR_TC, TIMER_CONTR_TC_CHANNEL);  

    //configuration input PIN

    static const gpio_map_t TC_GPIO_MAP =

    {

      {PIN_FOR_SPEED,AVR32_TC0_A2_3_FUNCTION }

    };

    gpio_enable_module(TC_GPIO_MAP, sizeof(TC_GPIO_MAP) / sizeof(TC_GPIO_MAP[0]));

}

//Function exact_geschwindigkeit

exact_geschwindigkeit (float *x,float *ges)

{   volatile avr32_tc_t *tc=TIMER_CONTR_TC;

    //initializing an array

    int tab[3]={0,0,0};

    //Writing in Register A and Register B

    tc_read_tc(TIMER_CONTR_TC,TIMER_CONTR_TC_CHANNEL);

    tc_write_ra(TIMER_CONTR_TC, TIMER_CONTR_TC_CHANNEL, tc_read_tc(TIMER_CONTR_TC,TIMER_CONTR_TC_CHANNEL));

    tc_write_rb(TIMER_CONTR_TC, TIMER_CONTR_TC_CHANNEL, tc_read_tc(TIMER_CONTR_TC,TIMER_CONTR_TC_CHANNEL));

    //filling the array

    tab[0]=tc_read_ra(TIMER_CONTR_TC,TIMER_CONTR_TC_CHANNEL);

    tab[1]=tc_read_rb(TIMER_CONTR_TC,TIMER_CONTR_TC_CHANNEL);

    float Ku=3.0f,Ui=10.0f;

    //restart the counter  

    //Speed calculation

    *ges=Ku*Ui*(tab[1]-tab[0])/(tab[2]-tab[0]);

    //reinitialization of the array 

    tab[2]=tab[0];

    *x=tc_read_tc(TIMER_CONTR_TC,TIMER_CONTR_TC_CHANNEL);

}

/*

 *

 *TimerContr.h

 *

*/

#ifndef _TIMERCONTR_H_

#define _TIMERCONTR_H_

#define PIN_FOR_SPEED               AVR32_TC0_A2_3_PIN  

#define TIMER_CONTR_TC             (&AVR32_TC0)              //defines the counter

#define TIMER_CONTR_TC_CHANNEL     2                        //Defines the channel

extern void exact_geschwindigkeit_init(void) ;              //initialization of the function

extern void exact_geschwindigkeit (float *x,float *ges);    //speed calculation

#endif