[AVR] UART with atmega128 question

[Justin Wenger]

guys, I want to make a UART code that prints '........' permanently and when I Interrupt(with INT0), it prints 'ppppp' instead, and when I interrupt again(with INT1), it prints '.....'again.

But the interrupt part isn't working.. The code works well printing '....' but even if I press INT0, nothing changes and it keeps printing '...'

if someone knows what the problem with this code is, please share your wisdom

#define F_CPU 16000000
#include <avr/io.h>
#include <avr/interrupt.h>

void uart0_init(void);
int Putchar(char message);
int x=0;
int main(void)
{
uart0_init();
while(1)
{
if(x==0)
{
Putchar('.');
}
if(x==1)
{
Putchar('p');
}
}
}


int interrupt(void)
{
EICRA = 0x0F; // Rising Edge detection
EIMSK = 0x03; // Set INT0 & INT1
SREG |= 0x80; // Global Interrupt Enable
while(1)
{

}
}

ISR(INT0_vect)
{
x++;
}

ISR(INT1_vect)
{
x--;
}


void uart0_init(void) {
UCSR0B = 0x00; //disable while setting baud rate
UCSR0A = 0x00;
UCSR0C = 0x06;
UBRR0L = 0x67; //set baud rate lo
UBRR0H = 0x00; //set baud rate hi
UCSR0B = 0x18;
}


int Putchar(char message) {// Putchar "P" cVde
while (((UCSR0A>>UDRE0)&0x01) == 0) ; // UDRE, data register empty
UDR0 = message;
return 0;
}

---

 

[FenTrac]

In the code posted, the function interrupt() is never called. It looks like this function defines and enables the interrupts. The function has a while(1) statement that would prevent it from returning if it was called.

 

[KlausST]

Hi,

Didn't go through the whole code...

But variables that are modified in the interrupt and used in the main loop need to be declared as "volatile".

What happens when "x < 0" or "x > 1" ?


Klaus

 

[danadakk]

I do not see where you executed attachInterrupt() ?

Arduino - Interrupts

Arduino - Interrupts - Interrupts stop the current work of Arduino such that some other work can be done.

www.tutorialspoint.com

Regards, Dana.

 

[Justin Wenger]

In the code posted, the function interrupt() is never called. It looks like this function defines and enables the interrupts. The function has a while(1) statement that would prevent it from returning if it was called.

I do not see where you executed attachInterrupt() ?

Arduino - Interrupts

Arduino - Interrupts - Interrupts stop the current work of Arduino such that some other work can be done.

www.tutorialspoint.com

Regards, Dana.

Thank you so much guys!! It works!!