UART with PC : Reciving absurd characters in PC

Question

I am working on a project using Atmega16 micro-controller of AVR family. I am using UART for my project. I need to send data to my PC AT 9600 baud rate via an USB-TTL converter and view the data using 'putty'.

I am getting absurd data in putty. I am not an electronics guy but a computer science guy so need a little bit of help.

I guess I might be writing the wrong fuse bits or something else. Please specify the fuse bits if possible

The program for the micro-controller is below

#include<avr/io.h>
#include<util/delay.h>

#define UBRR_VALUE 51

//function to initialize UART
void uart_init(void)
{
    UBRRH=(UBRR_VALUE>>8);//shift the register right by 8 bits
    UBRRL=UBRR_VALUE;//set baud rate
    UCSRB|=(1<<TXEN)|(1<<RXEN);//enable receiver and transmitter
    UCSRC|=(1<<URSEL)|(1<<UCSZ0)|(1<<UCSZ1);//8 bit data format
}

//function to transmit data
void uart_transmit(unsigned char data)
{
    while(!(UCSRA & (1<<UDRE)));
    UDR=data;
}

void transmit_string(char *str_data)
{
    while(*str_data)
    {
        uart_transmit(*str_data);
        str_data++;
    }
}

int main(void)
{
    uart_init();
    while(1)
    {
        //transmit_string("hello");
        uart_transmit('h');
    }
    return 0;
}

The fuse bits specifications are given below

Thanks in advance for any type of help

Answer 1

Your baud rate divisor seems to select a baud rate of 19200 instead of 9600:

baud = (clock speed) / ( 16 * (UBRR + 1) )

Try to set UBRR_VALUE to 103 and see if your communication gets better.

A proper way would be to define F_CPU and BAUD, and let the macros from setbaud.h do the calculation:

#include <avr/io.h>

#define F_CPU 16000000

static void
uart_9600(void)
{
#define BAUD 9600
#include <util/setbaud.h>
    UBRRH = UBRRH_VALUE;
    UBRRL = UBRRL_VALUE;
#if USE_2X
    UCSRA |= (1 << U2X);
#else
    UCSRA &= ~(1 << U2X);
#endif
}