Re: [avr-chat] Problem with USART on AVR

[jack]

Thankx for the reply Hugo.

The issue is resolved for now. I was using USB to serial cable on my 
laptop and that was causing the issue (not sure how).
I tried connecting directly to the serial port on my PC and everything 
works fine.

I have also pasted my USART code below:


#define    F_OSC      ((unsigned long) (12*1000000))
#define    BAUD_RATE  ((unsigned long) (19200))
#define    MYUBRR     ((unsigned long)(F_OSC/(unsigned 
long)(16*BAUD_RATE) - 1))

void
usart_init(void) {
   UBRRL = (unsigned char) (MYUBRR);
   UBRRH = (unsigned char) (MYUBRR >> 8);
   UCSRA &= !(1<<U2X);                  // Set U2X = 0
   UCSRB = (1<<RXEN) | (1<<TXEN);       // polling mode.
   UCSRC = (1<<USBS) | (3<<UCSZ0);      // No parity, 8 Databit, 1 stop 
bit.
}

void
usart_trx(char c) {
   while (!(UCSRA & (1<<UDRE)));
   UDR = c;
}

char
usart_rcx(void) {
   while (!(UCSRA & (1<<UDRE)));
   return UDR;
}

void
usart_trx_flash(const prog_char* str) {
   const prog_char *p=str;
   while (*p) {
       usart_trx(*p);
       p++;
   }
}

int
main(char **argv, char argc) {
   while(1) {
       usart_trx_flash("Hello, World!!\n");
   }
}

Thankx,
Jack

Hugo González Monteverde wrote:
> What baudrate are you using? What is the code you use for initializing 
> UBRRH and UBRRL?
>
> Looks like maybe you are using a high error baudrate with your clock....
>
> Hugo
>
> jack wrote:
> > Hi All,
> >
> > I am trying to run USART on ATTiny2313 at 12MHz but am seeing junk 
> > values in between at random. Sometimes some chars in the buffer are 
> > also skipped.
> > It's seen more often when i am transmitting anything from SRAM rather 
> > than FLASH.
>
>
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