AVR Freaks

/**
 * Program to toggle LED at 1 Hz or once every second for an input clock freq. of 16 MHz
 *
 * Timer resolution = Prescale/Input frequency
 * Input freq. = 16 MHz
 *
 * Target timer count = (((1/Target freq.)/Timer resolution) - 1)
 * 
 * Here target freq. = 1 Hz or once every second
 *
 */




#include 

int main(void) 
{
	DDRA |= _BV(PA4);
	TCCR1B |= _BV(CS12) | _BV(CS10);	//Use Prescaler of 1024

	while(1)
	{
		if(TCNT1 >= 15624)
		{
			PORTA ^= _BV(PA4);
			TCNT1 = 0;
		}
	}
}

#include 
//#include "pinsconfig.h"
#include "lcd.h"

#define F_CPU 16000000UL
#define serial_port PORTD
#define USART_BAUD_RATE 9600
#define BAUD_PRESCALE ((F_CPU / (USART_BAUD_RATE * 16UL)) - 1)

void usart_init(void);
void usart_putch(unsigned char send);
unsigned int usart_getch(void);

int main(void) {
	
	lcd_init(LCD_DISP_ON);	//initialize display, cursor off

	lcd_clrscr();
	PORTA = 0x00;
	DDRA |= _BV(PA4);
	DDRA |= _BV(PA5);
	unsigned char receivedByte;
	usart_init();
	while(1) {
		lcd_gotoxy(0,0);
		lcd_putc('X');

		PORTA |= _BV(PA5);

		receivedByte = usart_getch();	//get data from serial port

		usart_putch(receivedByte);	//send data back to PC

		lcd_gotoxy(0,0);
		lcd_putc(receivedByte);

		lcd_command(LCD_DISP_ON_CURSOR);	//turn on cursor

		lcd_command(LCD_DISP_ON);
	}
	return 0;
}

void usart_init(void) 
{
	UCSRB |= (1 << RXEN) | (1 << TXEN);	//Turn on transmission and reception

	UCSRC |= (1 << URSEL) | (1 << UCSZ0) | (1 << UCSZ1); //Use 8-bit character sizes

	//UBRR value = 103 which is 0x67 is hexadecimal

	UBRRH = (BAUD_PRESCALE >> 8);

	UBRRL = BAUD_PRESCALE;
}

void usart_putch(unsigned char send) {
	
	while(!(UCSRA & (1 << UDRE)));	//Do nothing until UDR is ready
										//for more data to be written to it
	UDR = send;	//send the byte
}

unsigned int usart_getch(void) {
	
	while(!(UCSRA & (1 << RXC)));	//Do nothing until data has been received and is ready to be read from UDR

	return UDR;	//return the byte
}