avr/usart/main.c

   1 #include <avr/io.h>
   2 #define F_CPU 1000000UL //1MHz default internal RC oscillator setting
   3 //util/delay.h and util/setbaud.h
   4
   5 #define USART_BAUDRATE 9600
   6 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)
   7
   8 int main (void)
   9 {
  10    char ReceivedByte;
  11
  12    UCSRB |= (1 << RXEN) | (1 << TXEN);   // Turn on the transmission and reception circuitry
  13    //UCSRC |= (1 << URSEL) | (1 << UCSZ0) | (1 << UCSZ1); // Use 8-bit character sizes (not in attiny2313?)
  14
  15    UBRRH = (BAUD_PRESCALE >> 8); // Load upper 8-bits of the baud rate value into the high byte of the UBRR register
  16    UBRRL = BAUD_PRESCALE; // Load lower 8-bits of the baud rate value into the low byte of the UBRR register
  17
  18    for (;;) // Loop forever
  19    {
  20       while ((UCSRA & (1 << RXC)) == 0) {}; // Do nothing until data have been received and is ready to be read from UDR
  21       ReceivedByte = UDR; // Fetch the received byte value into the variable "ByteReceived"
  22
  23       while ((UCSRA & (1 << UDRE)) == 0) {}; // Do nothing until UDR is ready for more data to be written to it
  24       UDR = ReceivedByte; // Echo back the received byte back to the computer
  25    }
  26 }
  27