Re: Serial communication of ATMega128

On Jan 31, 7:49 am, "sindhu" <scinthia_...@xxxxxxxxxxxxxx> wrote:
Hi all,
Iam working on Atmega128 and STK500.Iam new to this.
I need to transmit a character from controller.I have given the code
below.

#include"iom128v.h"
#include "io.h"

unsigned char data;
unsigned int baud;
unsigned int i;
int transmit(unsigned char);

void USART0_Init( unsigned int baud)
{
UBRR0H=0x96;
UBRR0L=0x00;
UCSR0B=0x08;
UCSR0C=0x06;}

int transmit(unsigned char data)
{
PORTA=0x41;
DDRA=0xFF;
loop_until_bit_is_set(UCSR0A,UDRE);
UDR0=data;
return 0;}

int main(void)
{
SREG=0x80;
SPL=0x61;
SPH=0x00;
USART0_Init(9600);
transmit('A');
return 0;}

This code is working.PORTA outputs 41.Hyperterminal is not showing
character A.
Can anyone point out the mistake?

Bye.


Looks like your baud rate is programmed to the wrong value. UBBR0H
should be the most significant byte of the divisor, and UBRR0L the
least significant byte.

For example, if your CPU clock is 4 MHz, and your baudrate 9600, the
divisor should be 4000000 / 16 / 9600 = 26.04, subtract one and round
to get 25. Program 0 (MSB) into UBRR0H, and 25 (LSB) into UBRR0L.

I always use something like this (with FCLK defined to be CPU clock):

int ubrr = (FCLK / baud + 8) / 16 - 1;

UBRR0H = (ubrr > 8);
UBRR0L = ubrr;

.

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