Arduino - Input capture programming

[Fe(II)man]

Howsit Guys,

my post today is with regard to monitoring the time between two events such as:

The time between a rising edge and a falling edge of a square wave that is connected to the input capture pin of the Arduino uno atmega328.

I wish to set up the micro to trigger upon a falling edge and thereafter save the value stored in the ICR and thereafter restart the timer on the next rising edge.

I can do this in assembly easily, just having a small problem using C in the arduino environment. Newbie in the arduino field.

Any help will be appreciated.

I would like some help in setting up the registers to monitor the ICP pin for the falling edge.

thanks

Atmega 328 datasheet:

http://www.atmel.com/Images/8271s.pdf

 

[Fe(II)man]

code I have so far:

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Code C - [expand]
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#include <avr/io.h> 
#include <avr/interrupt.h> 
 
// Set up input capture mode
// Set up timers
// Set up port for output
 
unsigned int Period;
 
void setup(void) 
{ 
  Serial.begin(9600); 
  DDRB |= 0x01; 
  
  Init(); 
  
  Serial.println("Init finished"); 
} 
 void loop(void)
 {
   while(1)
   {
     Serial.print(" ");
   }
 } 
 
void Init(void) 
{ 
    //init Port B0 
    DDRB &= ~0x01;   // make ICP1 pin i/p 
    //init timer registers
    TCCR1A = 0x00;   // Normal Mode
    TCCR1B = 0x05; // prescalar 1024
    TIMSK1 = 0x21;  //-Interrupt enable 
                     // Timer overflow enable 
    TCNT1 = 0; 
    //Clear flags in Timer flag reg 1
    TIFR1  = 0x21;              //0x21; 
} 
 
// ISR for falling edge
ISR(TIMER1_CAPT_vect) 
{ 
  if((PINB & (1<<PORTB0)) == 0)       // capture falling edge 
  { 
    Period = ICR1; 
    TCNT1 = 0;               //Reset timer 1
    TCCR1A = 0x00;
    PORTB = PORTB^0x20;       // toggle PB5 pin 
  } 
}

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