/**
* see http://arduino.cc/en/Reference/PortManipulation#.Uyrot9wh6IF
*
* You can read what state a pin has by using bitRead and PORTD or PORTB or PORTC
*
* PORTD are pins 0 to 7
* PORTB are pins 8 to 13 (bits (6 & 7) map to the crystal pins and are not usable)
* PORTC are analog pins 0 to 5 (Pins 6 & 7 are only accessible on the Arduino Mini)
*
* so to get the current state of e.g. pin 13 you do a bitRead(PORTB,5)
*
* to get the state of pin 3 do bitRead(PORTD, 3) and so on
*/
int pin = 13;
void setup(){
pinMode(pin, OUTPUT);
Serial.begin(9600);
}
void loop(){
delay(1000);
digitalWrite(pin, HIGH);
Serial.println(bitRead(PORTB,5)); //Reads bit 5 of register PORTD which contains the current state (high/low) of pin 13.
delay(1000);
digitalWrite(pin, LOW);
Serial.println(bitRead(PORTB,5)); //Reads bit 5 of register PORTD which contains the current state (high/low) of pin 13.
}