USART interrupt ATMega168

thebignoob · Aug 21, 2014

Hello,
I was using USART interrupts to handle data transfer from PC to uC so that I could send that data to another remote PC using nRF24L01. Everything worked just fine with ATMega88, but on one side i had to switch to ATMega168 and then...

everything stop working ...
So I tried to debug it... one thing at the time...

USART communication is working when I send some data from PC to uC and back... But when i try to do that using USART interrupt problem occurs... When I enter any character from terminal it goes crazy .... starts printing some symbols and blinking dash goes left to right all the time (pretty fast)... I go back again to ATMega88 and everything works...

Usart init and 2 functions that i used for communication ....

Code:

void usart_init(void)
{
        unsigned int USART_BAUDRATE = 9600;		
	unsigned int ubrr = (((F_CPU / (USART_BAUDRATE * 16UL))) - 1);	

	UBRR0H = (unsigned char)(ubrr&gt;&gt;8);
	UBRR0L = (unsigned char)ubrr;

	UCSR0B = (1&lt;&lt;RXEN0)|(1&lt;&lt;TXEN0);

	UCSR0C = (1&lt;&lt;USBS0)|(3&lt;&lt;UCSZ00);
}

void usart_transmit(uint8_t data)
{
	while ( !( UCSR0A &amp; (1&lt;&lt;UDRE0)) );
	UDR0 = data;
}

uint8_t usart_receive( void )
{
	return UDR0; 
}

Enable usart interrupt

Code:

UCSR0B |= (1&lt;&lt;RXCIE0);

ISR

Code:

ISR(USART_RX_vect)
{
	uint8_t W_buffer[8];

	int i;
	for (i=0;i&lt;8;i++)
	{
		W_buffer[i]=usart_receive();	
		usart_transmit(W_buffer[i]);			
	}	

	usart_transmit('#');	
 }

I tried printing something at the beginning of the ISR to see if it goes inside but that never happens.
Anyone have a idea what could be the issue here ? I feel i just go round and round in circles....

liquibyte · Aug 21, 2014

Have you tried an AVR forum? I suspect the difference from working to not will be in the differences between the chips themselves.

USART interrupt ATMega168

USART interrupt ATMega168

thebignoob

liquibyte

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