Handle switch input

The `input` enum is extended with `click` and `hold` values and all
dependencies are adapted to that. In order to handle the `click` input
an interrupt is used. Further, for handling held button input with the
switch the Timer/Counter1 compare match interrupt with OCR1A is used.

firmware/src/main.c

@@ -58,7 +58,7 @@ static const struct symbol sym_9 = { 5, { 0xF8, 0xFC, 0x8C, 0xFC, 0xF8,
 static const struct symbol sym_setup = { 19, { 0xF8, 0x98, 0xB8, 0x00, 0xF8, 0x98, 0x18, 0x00, 0x18, 0xF8, 0x18, 0x00, 0xF8, 0x00, 0xF8, 0x00, 0xF8, 0x98, 0xF8,
                                                0x1D, 0x19, 0x1F, 0x00, 0x1F, 0x19, 0x18, 0x00, 0x00, 0x1F, 0x00, 0x00, 0x1F, 0x18, 0x1F, 0x00, 0x1F, 0x01, 0x01 } };
 
-enum input {cw, ccw};
+enum input {cw, ccw, click, hold};
 
 static enum state {home} current_state = home;
 static enum home_state {ch1, ch2, ch3, setup} current_home_state = ch1;
@@ -253,6 +253,10 @@ static void update_home(enum input event) {
             current_home_state = setup;
         lcd_home();
         break;
+    case click:
+        break;
+    case hold:
+        break;
     }
 }
 
@@ -310,12 +314,45 @@ ISR(PCINT0_vect) {
         break;
     }
 
-    // TODO: proper debounce and dechattering
+    // TODO: proper dechattering
     _delay_us(100);
 
     sei();
 }
 
+// encoder button interrupt
+ISR(PCINT1_vect) {
+    cli();
+
+    if (PINC & (1 << PC0)) { // release
+        TCCR1B &= (0 << CS11) & (0 << CS10); // Disable Timer/Counter1
+        if (TCNT1 != 0) {
+            update_state(click); // Switch to selected state
+            TCNT1 = 0;
+        }
+    } else { // press
+        if (!(TCCR1B & (1 << CS10))) {
+            TCCR1B |= (1 << CS11) | (1 << CS10); // Enable Timer/Counter1
+        }
+    }
+
+    // TODO: proper debouncing
+    _delay_us(70);
+
+    sei();
+}
+
+// Timer/Counter1 compare match A
+ISR(TIMER1_COMPA_vect) {
+    cli();
+
+    TCCR1B &= (0 << CS11) & (0 << CS10); // Disable Timer/Counter1
+    TCNT1 = 0;
+    update_state(hold);
+
+    sei();
+}
+
 int main(void) {
     // FastPWM: 1.25kHz
     // TODO: Try to get the backlit even more dim
@@ -334,6 +371,15 @@ int main(void) {
     PCICR |= (1 << PCIE0);
     PCMSK0 |= (1 << PCINT6) | (1 << PCINT7);
 
+    // Encoder switch setup
+    PORTC |= (1 << PC0);
+    PCICR |= (1 << PCIE1);
+    PCMSK1 |= (1 << PCINT8);
+
+    // Timer1 setup to recognize held button
+    OCR1A = 8192;
+    TIMSK1 |= (1 << OCIE1A); // Enable match compare A
+
     // Show splash screen and load the menu
     lcd_splash();
     _delay_ms(250);