Serial output

If you want to read the value of a variable inside your MCU, the easiest option is to just print it on the serial port.

TX-pin is PIN_PA1.

Calibrate your MCU-clock

1. Set the fuse to enable clock output on PIN_PB2.
2. Use a frequency counter (or an oscilloscope) to measure the frequency.
3. When it's not correct you can adjust the frequency using the OSCCAL-register:

   void setup()
   {
       OSCCAL-=4;
   }
   

Disabling RX

void setup()
{
    OSCCAL-=5;//999.178kHz
    Serial.begin(4800);
    //Disable Serial RX
    ACSR &=~(1<<ACIE);
    ACSR |=~(1<<ACD);
}

void loop()
{
    Serial.print("Hello");
    delay(1000);
}