serial.c

#include <avr/io.h>
#include <util/delay.h>
#define F_CPU 16000000UL

void mySerialBegin(int baudRate) {
   UCSR0B |= (1 << RXEN0) | (1 << TXEN0);   // Turn on the transmission and reception circuitry 
   UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); // Use 8-bit character sizes 

   UBRR0H = (baudRate >> 8); // Load upper 8-bits of the baud rate value into the high byte of the UBRR register 
   UBRR0L = (((F_CPU / (baudRate * 16UL))) - 1); // Load lower 8-bits of the baud rate value into the low byte of the UBRR register 
}

char mySerialRead() {
   char ReceivedByte;
   while ((UCSR0A & (1 << RXC0)) == 0) {}; // Do nothing until data have been received and is ready to be read from UDR 
   ReceivedByte = UDR0; // Fetch the received byte value into the variable "ByteReceived" 
   return ReceivedByte;
}

void mySerialPrint(char data) {
   while ((UCSR0A & (1 << UDRE0)) == 0) {}; // Do nothing until UDR is ready for more data to be written to it 
   UDR0 = data; // Echo back the byte back to the computer   
}

void mySerialPrintln(char data) {
  mySerialPrint(data);
  mySerialPrint('\n');
}

int main(void) 
{ 
   char ReceivedByte; 
   mySerialBegin(9600);
   for (;;) // Loop forever 
   {  
      ReceivedByte = mySerialRead(); 
      mySerialPrintln(ReceivedByte);
   }    
}

#include <avr/io.h>
#include <util/delay.h>
#define BAUD_RATE 9600
#define BAUD_PRESCALE (((F_CPU / (BAUD_RATE * 16UL))) - 1)

void mySerialBegin(int baudRate) {
UCSR0B |= (1 << RXEN0) | (1 << TXEN0); // Turn on the transmission and reception circuitry
UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); // Use 8-bit character sizes

UBRR0H = (BAUD_PRESCALE >> 8); // Load upper 8-bits of the baud rate value into the high byte of the UBRR register
UBRR0L = BAUD_PRESCALE; // Load lower 8-bits of the baud rate value into the low byte of the UBRR register
}

char* mySerialRead() {
loop_until_bit_is_set(UCSR0A, RXC0); /* Wait until data exists. */
return UDR0;
}

void mySerialPrint(char* data) {
for (int i = 0; i < strlen(data); i++){
UDR0 = data[i];
loop_until_bit_is_set(UCSR0A, TXC0); /* Wait until transmission ready. */
}
}

void mySerialPrintln(char data) {
mySerialPrint(data);
mySerialPrint('\n');
}

int main(void)
{
char* ReceivedByte;
mySerialBegin(9600);
for (;;) // Loop forever
{
ReceivedByte = mySerialRead();
mySerialPrint(ReceivedByte);
}
}