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diff --git a/spaghetti-monster/fsm-pcint.c b/spaghetti-monster/fsm-pcint.c
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+++ b/spaghetti-monster/fsm-pcint.c
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+/*
+ * fsm-pcint.c: PCINT (Pin Change Interrupt) functions for SpaghettiMonster.
+ *
+ * Copyright (C) 2017 Selene ToyKeeper
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef FSM_PCINT_C
+#define FSM_PCINT_C
+
+#include <avr/interrupt.h>
+#include <util/delay_basic.h>
+
+uint8_t button_is_pressed() {
+    // remember the past 32 measurements
+    static uint32_t readings = 0;
+    // take at least one new measurement,
+    // and wait for measurements to settle to all zeroes or all ones
+    do {
+        // shift past readings and add current value
+        readings = (readings << 1) | ((PINB & (1<<SWITCH_PIN)) == 0);
+        // wait a moment
+        _delay_loop_2(BOGOMIPS/16);  // up to 2ms to stabilize
+    }
+    while ((readings != 0) && (readings != 0xFFFFFFFF));
+    button_last_state = readings;
+    return readings;
+}
+
+inline void PCINT_on() {
+    // enable pin change interrupt for pin N
+    GIMSK |= (1 << PCIE);
+    // only pay attention to the e-switch pin
+    //PCMSK = (1 << SWITCH_PCINT);
+    // set bits 1:0 to 0b01 (interrupt on rising *and* falling edge) (default)
+    // MCUCR &= 0b11111101;  MCUCR |= 0b00000001;
+}
+
+inline void PCINT_off() {
+    // disable all pin-change interrupts
+    GIMSK &= ~(1 << PCIE);
+}
+
+//void button_change_interrupt() {
+EMPTY_INTERRUPT(PCINT0_vect);
+/*
+ISR(PCINT0_vect) {
+
+    //DEBUG_FLASH;
+
+    // as it turns out, it's more reliable to detect pin changes from WDT
+    // because PCINT itself tends to double-tap when connected to a
+    // noisy / bouncy switch (so the content of this function has been
+    // moved to a separate function, called from WDT only)
+    // PCINT_inner(button_is_pressed());
+
+}
+*/
+
+// should only be called from PCINT and/or WDT
+// (is a separate function to reduce code duplication)
+void PCINT_inner(uint8_t pressed) {
+    uint8_t pushed;
+
+    if (pressed) {
+        pushed = push_event(A_PRESS);
+    } else {
+        pushed = push_event(A_RELEASE);
+    }
+
+    // check if sequence matches any defined sequences
+    // if so, send event to current state callback
+    if (pushed) {
+        button_last_state = pressed;
+        emit_current_event(0);
+    }
+}
+#endif