Serial.c

/* ************************************************************************* */ /* */ /* Description  : UART communication routines */ /* Based on AppNote AVR109 - Self-programming */ /* */ /* FileName  : serial.c */ /* */ /* ************************************************************************* */

1. include <avr\io.h>

// Following calculation assumes that F_CPU is assigned in 'Project/Options'

1. define BAUDRATE 4800
2. define BAUD_PRESCALE (((F_CPU / (BAUDRATE * 16UL))) - 1)

/* definitions for UART control */

                                       // Valid for ATmega328

1. define BAUD_RATE_REG UBRR0 //
2. define UART_STATUS_REG UCSR0A // OK, checked (but also control reg.)
3. define UART_CONTROL_REG_B UCSR0B // OK, checked
4. define UART_CONTROL_REG_C UCSR0C // Added for mode setting
5. define ENABLE_TRANSMITTER_BIT TXEN0 // OK, checked
6. define ENABLE_RECEIVER_BIT RXEN0 // OK, checked
7. define DATA_REGISTER_EMPTY_BIT UDRE0 // Added, for possible speed-up
8. define TRANSMIT_COMPLETE_BIT TXC0 // OK, checked
9. define RECEIVE_COMPLETE_BIT RXC0 // OK, checked
10. define UART_DATA_REG UDR0 // OK, checked

void inituart(void) {

BAUD_RATE_REG = (unsigned char)BAUD_PRESCALE;    // Set baud rate: Load the UBRR register

UART_CONTROL_REG_B = (1 << ENABLE_RECEIVER_BIT)|
                   (1 << ENABLE_TRANSMITTER_BIT); // Enable receive + transmit 

UART_CONTROL_REG_C = (3<<UCSZ00);                 // Added: Async. UART, None 
                                                  // Parity, 8-data, 1 stopbit
                                                  

}

void sendchar(unsigned char c) {

 UART_DATA_REG = c;                                   // prepare transmission
 while (!(UART_STATUS_REG & (1 << TRANSMIT_COMPLETE_BIT)));// wait until byte sendt
 UART_STATUS_REG |= (1 << TRANSMIT_COMPLETE_BIT);          // delete TXCflag

}

unsigned char recchar(void) {

 while( !(UART_STATUS_REG & (1 << RECEIVE_COMPLETE_BIT)) );  // wait for data
 return UART_DATA_REG;

}