Code (C++)

//Red Green Indicator
const byte IndicatorLedRed = PIN_B0;
const byte IndicatorLedRedRegPos = PINB0;
const byte IndicatorLedGreen = PIN_B1;
const byte IndicatorLedGreenRegPos = PINB1;

byte MainLoopCount;

void setup()
{
	DDRB = DDRB |  (1 << IndicatorLedRedRegPos) | (1 << IndicatorLedGreenRegPos);// initialize the indicator pins
	USART0_Init(25);// Set the baudrate to 2400 bps using a 1 MHz
}

void loop(void)
{
	MainLoopCount = 1;
	while (MainLoopCount)	//flash indicator green/red 5 times to show startup
	{
		digitalWrite(IndicatorLedGreen, HIGH);
		delay(2000);
		digitalWrite(IndicatorLedGreen, LOW);
		delay(200);
		digitalWrite(IndicatorLedRed, HIGH);
		delay(2000);
		digitalWrite(IndicatorLedRed, LOW);
		delay(200);
		--MainLoopCount;
	}
	USART0_Transmit(char('5'));//send unsigned character
}

void USART0_Init(unsigned int baud)// Initialize UART
{ 
	UBRR0H = (unsigned char)(baud >> 8);// Set baud rate
	UBRR0L = (unsigned char)baud;
	//UCSR0B = (1 << RXEN0) | (1 << TXEN0);//Enable receiver and transmitter
	UCSR0B = (1 << TXEN0);//Enable transmitter
	UCSR0C = (1 << USBS0) | (3 << UCSZ00);// Set frame format: 8data, 2stop bit
}

void USART0_Transmit(unsigned char data)//send serial
{
	while (!(UCSR0A & (1 << UDRE0)));// Wait for empty transmit buffer
	UDR0 = (data);// send a single byte
}