HI,
I have a simple code that receives and transmits string through UART. I use ATMEGA 168.
So according to my code I transmit a string using cool term and the controller receives it.The controller the compares the string .If the strings match then the controller sends back "K" , which will be displayed in the cool term.
If the strings don't match the controller sends back"AT" followed by carriage return and new line.
But when I execute the code and if the strings don't match it returns back "AT";but I do not get a new line.It prints "AT" continuously.
#include <avr/io.h>
#include <string.h>
#include <util/delay.h>
#define F_CPU 8000000UL
#define BAUD 9600
#define MYUBBR F_CPU/16/BAUD-1
void uart_init(unsigned int ubrr)
{
// Setting the baud rate to ubrr
UCSR0A = 0<<U2X0;
UBRR0H = (unsigned char)(ubrr >> 8);
UBRR0L = (unsigned char)ubrr;
//Setting the frame format to 8 data bit, no parity bit, 1 stop bit
UCSR0C = 3<<UCSZ00;
UCSR0B = (1<<TXEN0)|(1<<RXEN0);
}
void USART_Transmit( unsigned char data )
{
while (!(UCSR0A & (1<<UDRE0)));
UDR0 = data;
}
unsigned char USART_Receive()
{
while (!(UCSR0A & (1<<RXC0)));
return UDR0;
}
void transmit_string(char* data)
{
int i;
for (i=0;data[i] != '\0';i++)
{
USART_Transmit(data[i]);
}
}
void receive_string(char* dat)
{
char command[4];
command[0] = '\0';
command[1] = '\0';
command[2] = '\0';
command[3] = '\0';
int index = 0;
while ((command[2] != 0x0D) && (command[3] != 0x0A))
{
dat
= USART_Receive();
index += 1;
if (index > 3)
{
command[0] = dat[index - 4];
command[1] = dat[index - 3];
command[2] = dat[index - 2];
command[3] = dat[index - 1];
}
}
dat[index-2] = '\0';
}
int main(void)
{
// Setting system clock to 8MHz
CLKPR = (1 << CLKPCE);
CLKPR = 0;
uart_init(MYUBBR);
while(1==1)
{
char dat[10];
receive_string(dat);
if(strcmp(dat,"OK")==0)
{
UDR0='k';
}
else
{
char data[]="AT";
transmit_string(data);
UDR0='\r';
UDR0='\n';
_delay_ms(1000);
}
}
}
Kindly point out the mistake .
