/*
 * Setting up I/O pins for
 * - Switch 1 (normally closed/on)
 * - Switch 2 (normally open/off)
 *
 * There is only a limited set of I/O pins for each type of
 * Arduino that can be attached to an external interrupt.
 * Most (if not all) ATMega-based Arduino boards support
 * external interrupts on I/O pins 2 and 3.
 */

#define PIN_SWITCH1 2
#define PIN_SWITCH2 3

/*
 * Optimal debouncing times may vary be tween different dials.
 * The below values work best with _MY_ dial.
 *
 * -> Change SWITCH1 debouncing time if the number detected is
 *    not correct
 * -> Change SWITCH2 debouncing time if turning/reaching
 *    initial resting position is not detected properly
 */

#define SWITCH1_DEBOUNCING_MILLIS 65
#define SWITCH2_DEBOUNCING_MILLIS 100

/*
 * Global variables for exchanging values between interrupt calls, namely:
 * - debouncing buffers, storing when an interrupt routine was last called
 * - pulse count, incremented while the dial is turned
 */

volatile unsigned long switch1_debouncing_millis_last = 0;
volatile unsigned long switch2_debouncing_millis_last = 0;
volatile byte switch1_num_pulses = 0;

/*
 * Setup routine - putting everything into order
 */

void setup() {
	// Initialize serial and wait for port to open:
    Serial.begin(115200);
    while (!Serial) {/* just wait */}
    Serial.println("Serial ready.");
    Serial.print("Setting up pins...");
    pinMode(PIN_SWITCH1, INPUT);
    pinMode(PIN_SWITCH2, INPUT);
    Serial.println("done");
    Serial.print("Attaching interrupt...");
    //wait for closing of Switch 2 before doing anything else
    attachInterrupt(digitalPinToInterrupt(PIN_SWITCH2), isr_switch2_rising, RISING);
    Serial.println("done");
}

/*
 * Here goes the main program code... just in case you
 * want to do anything besides just detecting numbers
 */
void loop() {
}

/*
 * Interrupt routine, called when Switch 2 is closed.
 * It marks the beginning of dialling and replaces itself with the 
 * interrupt routine waiting for Switch 2 to open again and
 * attaches the interrupt to Switch 1 in order to count the pulses
 */

void isr_switch2_rising() {
	long diff = millis() - switch2_debouncing_millis_last;
	diff = abs(diff);
	if (diff >= SWITCH2_DEBOUNCING_MILLIS) {
		Serial.print("turn of dial detected - counting pulses: [");
		switch1_num_pulses = 0;
		attachInterrupt(digitalPinToInterrupt(PIN_SWITCH1), isr_switch1_falling, FALLING);
		attachInterrupt(digitalPinToInterrupt(PIN_SWITCH2), isr_switch2_falling, FALLING);
		switch2_debouncing_millis_last = millis();
		switch1_debouncing_millis_last = millis();
}

/*
 * Interrupt routine, called when Switch 1 is opened
 * (marking a pulse). It is only active while
 * Switch 2 is closed and increments the global
 * variable "switch1_num_pulses"
 */

void isr_switch1_falling() {
	long diff = millis() - switch1_debouncing_millis_last;
	diff = abs(diff);
	if (diff >= SWITCH1_DEBOUNCING_MILLIS) {
		Serial.print(".");
		switch1_num_pulses++;
		switch1_debouncing_millis_last = millis();
    }
}

/*
 * Interrupt routine, called when Switch1 is opened.
 * It marks the end of dialling and:
 * - prints the detected number of pulses to the serial console
 * - detaches the interrupt routine from Switch1
 * - replaces itself with the interrupt routine waiting for Switch 2
 *   to close again and could be your starting point if you intend to do
 *   anything beyond simple numeral detection and output to the serial 
 *   console.
 */

void isr_switch2_falling() {
	long diff = millis() - switch2_debouncing_millis_last;
	diff = abs(diff);
	if (diff >= SWITCH2_DEBOUNCING_MILLIS) {
		// do something with the detected number...
		Serial.print("]");
	for (byte b = 0; b < (11-switch1_num_pulses); b++) 
		Serial.print(" ");
		Serial.print(" detected");
		Serial.print(switch1_num_pulses);
	 	Serial.print(" pulse");
		Serial.println((switch1_num_pulses != 1 ? "s" : ""));
		switch2_debouncing_millis_last = millis();
		detachInterrupt(digitalPinToInterrupt(PIN_SWITCH1));
		attachInterrupt(digitalPinToInterrupt(PIN_ SWITCH2), isr_switch2_rising, RISING);
		switch2_debouncing_millis_last = millis();
	}
}