AVR Freaks

/* io.h contains the defines for USART registers */
#include 
#include "delay_x.h"


/* Defines to calculate the UBBR value based on 12Mhz clock speed
** and 250 000 baud. */
#define F_CPU 12000000L
#define FOSC 12000000L
#define BAUD 250000
#define MYUBRR FOSC/16/BAUD-1
#define dmx_ch 192

#define LED_PORT	PORTD
#define LED_IO		PD6		// indicates program initialisation status
#define LED_USART	PD5		// Indicates USART initialieds
#define LED_TRIG	PD4		// Really for testing purposes only.  toogles with start frame
#define LED_DATA	PD3		// 
#define IO_TRIG	PD2		// Really for testing purposes only.  toogles with start frame
#define IO_TX		PD1		// Tx Pin of USART 

void USART_init(unsigned int ubrr);
void USART_tx(unsigned char data);

int main()
{
   unsigned char count;
   unsigned char x;
	DDRD = 0b01111001;  
	LED_PORT &= 0x00;

	LED_PORT |= (1<<LED_IO);		// set bit 7

	USART_init( MYUBRR );
	LED_PORT |= (1<<LED_USART);		// set bit 6

   while(1)
   {
		LED_PORT  &=~(1<<IO_TX);	// 'start' frame is low for 88 to 100 us
		LED_PORT |=(1<<IO_TRIG);	// Set trigger high for testing only
		LED_PORT |=(1<<LED_TRIG);	// turn Trigger LED on

		_delay_us(94);				// this delay is twicked  
		LED_PORT |=(1<<IO_TX);		// MAB is high for atleast 8 us
		LED_PORT  &=~(1<<IO_TRIG);	// Set the trigger pulse low  
		_delay_us(10);
		
		UCSRA = (1<<TXC);			// Clear out any 	
	   	UCSRB = (1<<TXEN);			// Enable tx portion of the USART
		LED_PORT  &=~(1<<LED_TRIG);	// Turn Trigger LED off  
		x = 0x00;
		for (count=1; count <= dmx_ch; count++)	
		{								// the first word has all 0s indication start co
			USART_tx(x);
			x=x+0x01;
		}
		while (!(UCSRA&(1<<TXC)));	// wait here until the last data bit is TXd		
		UCSRB &=~(1<<TXEN);			// disable the TX portion of the Usart

   }
   return(0);
}

/*********** USART_tx ******************************************/

void USART_tx(unsigned char data)
{
   while( !( UCSRA & (1<<UDRE)) )
      ;
   UDR = data;
}

/*********** USART_init ******************************************/
void USART_init(unsigned int ubrr)
{
   	/* set baud rate, UBRRH is not used for this example */
   	UBRRH = (unsigned char)(ubrr>>8);
   	UBRRL = (unsigned char)ubrr;

   	/* Don't enable rx and tx YET*/
//   	UCSRB = (1<<RXEN) | (1<<TXEN);
		UCSRB &= ~(1 << RXEN) ;
		UCSRB &= ~(1 << TXEN) ;


   	/* set frame settings to 8 data, 2 stop bit */
	UCSRC = (1<<USBS) | (3<<UCSZ0);
}