AVR, UART

Hello,

I have got AVR ATmega16.
I attached 11059000 Hz oscilator
to XTAL1 and XTAL2 (+capacitors).

I can send data to the processor (UART) but
got wrong characters.
Probably, I haven`t set frequency
parameters correctly.

Do I have to set some extra things
in the code to use external oscilator
for UART?

What to do to make AVR's UART
working with 11,059MHz oscilator?


Piece of the code:

UART.h:
----------

#ifndef _UART_H_
#define _UART_H_

enum {
    RECVBUF_MAX = 16,
    FCPU = 11059000,
    VUART = 57600,
    VUBRR = FCPU / (VUART * 16) - 1
};

void initUART(void);

#endif



UART.c:
----------

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/signal.h>
#include <string.h>
#include "uart.h"

void initUART(void)
{
    UBRRH = (unsigned char)(VUBRR >> 8);
    UBRRL = (unsigned char)VUBRR;

     UCSRB = (1 << RXCIE) | (1 << TXCIE) | (1 << RXEN);

    /* 8, 1 stop */
    UCSRC = (1 << UCSZ1) || (1 << UCSZ0);

    sei();
}


char recvBuf[RECVBUF_USER_MAX] = "\0";
volatile char *recvBufPtr = recvBuf;
volatile int flagaaa = 0;

SIGNAL (SIG_UART_RECV)
{
    if (recvBufPtr - recvBuf < RECVBUF_MAX)
        *recvBufPtr++ = UDR;
}

"Umpa" <&#4294967295;&#4294967295;&#4294967295;&#4294967295;@umpaumpalala.com> wrote in news:c7tot0$nf7$1
@atlantis.news.tpi.pl:

> Hello,
> 
> I have got AVR ATmega16.
> I attached 11059000 Hz oscilator
> to XTAL1 and XTAL2 (+capacitors).
> 
> I can send data to the processor (UART) but
> got wrong characters.
> Probably, I haven`t set frequency
> parameters correctly.
> 
> Do I have to set some extra things
> in the code to use external oscilator
> for UART?
> 
> What to do to make AVR's UART
> working with 11,059MHz oscilator?

Have you set the fuses to use an external XTAL ? if you have not you will 
still be using the internal 1MHz RC-oscilator (as that's how Mega16's 
come out of the factory :) ).

Note when setting the fuses be carefull to set them for external XTAL and 
*NOT* external oscilator.

Hope that helps.

Phill.

> Have you set the fuses to use an external XTAL ? if you have not you will
> still be using the internal 1MHz RC-oscilator (as that's how Mega16's
> come out of the factory :) ).
>
In the aplication I use to program my processors there are a few
fuses for XTAL: XTAL<0.4MHz,  XTAL 0.4-0.9 MHz,
XTAL 0.9-3 MHz, XTAL 3-8 MHz.
I have got about 11 MHz oscilator which is faster than the fasters
fuse XTAL 3-8 MHz. I don`t know what to set.

Umpa.

"Umpa" <&#4294967295;&#4294967295;&#4294967295;&#4294967295;@umpaumpalala.com> wrote in message
news:c7vap2$n7e$1@atlantis.news.tpi.pl...
> > Have you set the fuses to use an external XTAL ? if you have not you
will
> > still be using the internal 1MHz RC-oscilator (as that's how Mega16's
> > come out of the factory :) ).
> >
> In the aplication I use to program my processors there are a few
> fuses for XTAL: XTAL<0.4MHz,  XTAL 0.4-0.9 MHz,
> XTAL 0.9-3 MHz, XTAL 3-8 MHz.
> I have got about 11 MHz oscilator which is faster than the fasters
> fuse XTAL 3-8 MHz. I don`t know what to set.

Do yourself a favour and download the most recent version of AVRStudio at
www.atmel.com

Meindert