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Software => Software => Topic started by: Trumpkin on August 22, 2008, 07:09:21 PM

Title: analogRead
Post by: Trumpkin on August 22, 2008, 07:09:21 PM

Hey people, when I try to compile this code I get this error "undefined reference to analogRead". Is there a library or something I'm supposed to include?

Code: [Select]

/* Blinker Demo */

/* Include useful pre-defined functions*/
#include <avr/interrupt.h>    // Defines pins, ports, etc to make programs easier to read
#define F_CPU 100000UL       // Sets up the default speed for delay.h
#include <util/delay.h>
int IR_pin = 5;
int val = 0;     //a variable to store IR value
int IR_thresh = 100;   

int main()
{
for ( ;; )
{
  val = analogRead(IR_pin);
  if (val < IR_thresh)
{
  DDRD = _BV(PD7); // enable output on port D, pin 7
 
    PORTD = _BV(PD7);
    _delay_ms(1000);

    PORTD &= ~_BV(PD7);
    _delay_ms(1000);
}
}
  return(0);
}


Title: Re: analogRead
Post by: Admin on August 22, 2008, 10:12:48 PM

Where did this line come from?
val = analogRead(IR_pin);

Anyway, the error is because you need to declare what analogRead() is before you use it.

For example:

Code: [Select]

int IR_thresh = 100;   

void analogRead(int pin);//declare here, then define it somewhere else

int main()
{


Title: Re: analogRead
Post by: pomprocker on August 22, 2008, 11:07:35 PM

you can either just declare, or declare and initialize.

<data_type> <variable>;

or

<data_type> <variable> = <number to initialize with>


ex:

int val;

or

int val = 0;

Title: Re: analogRead
Post by: Trumpkin on August 27, 2008, 10:02:50 AM

I got the code to compile and download on to my microcontroller but the LED just blinked randomly.  :-\ I wanted the LED to blink when my hand got close to the Sharp IR. I changed the code a bit, heres what I want it to do
 auto calibrate
 blink the LED to let you know that it has calibrated
 when an object gets within the calibrated range have the LED blink
I probably have a lot of things wrong since I'm not very good at programming yet.

Code: [Select]

/* Blinker Demo */

/* Include useful pre-defined functions*/
#include <avr/interrupt.h>    // Defines pins, ports, etc to make programs easier to read
#define F_CPU 100000UL       // Sets up the default speed for delay.h
#include <util/delay.h>
#include <SoR_Utils.h>
int IR_pin = 5; 
int val = 0;     
int main()
{
//automatically calculates threshold value before run
int IR_thresh=a2dConvert8bit(IR_pin);//sensor reading
PORT_ON(PORTD, 7);
_delay_ms(5000);
PORT_OFF(PORTD, 7);
_delay_ms(5000);

       for ( ;; ) //loops forever
    {
   
  val = a2dConvert8bit(IR_pin);
  if (val < IR_thresh)
{
  PORT_ON(PORTD, 7);
  _delay_ms(1000);

  PORT_OFF(PORTD, 7);
  _delay_ms(1000);
                    }

}
  return(0);
}




Title: Re: analogRead
Post by: airman00 on August 27, 2008, 10:55:15 AM

Heres the pseudo code

Code: [Select]

Read value of Sharp and store in variable "distance"
If distance is more than threshold Then  // I wrote more because the Sharp IR returns a higher value the closer you are
        Flash_LED
Else
         Turn_LED_Off
Endif
Loop

The actual C code is pretty simple , the most complicated part I could think of is getting the values of the Sharp IR sensor and see the values for close objects and the values for further. If I remember correctly the closer u are the higher the value - but I am not sure , the last time I used a Sharp IR sensor was in that electronics book combination lock.