From 8d2f442317fd3678213a14307f95d2f5b54c5623 Mon Sep 17 00:00:00 2001
From: Selene ToyKeeper
Date: Sat, 19 Aug 2017 12:17:58 -0600
Subject: Renamed from RoundTable to SpaghettiMonster (FSM).

---
 spaghetti-monster/fsm-ramping.h       |  26 ++
 spaghetti-monster/momentary.c         |  85 ++++
 spaghetti-monster/spaghetti-monster.h | 737 ++++++++++++++++++++++++++++++++++
 3 files changed, 848 insertions(+)
 create mode 100644 spaghetti-monster/fsm-ramping.h
 create mode 100644 spaghetti-monster/momentary.c
 create mode 100644 spaghetti-monster/spaghetti-monster.h

(limited to 'spaghetti-monster')

diff --git a/spaghetti-monster/fsm-ramping.h b/spaghetti-monster/fsm-ramping.h
new file mode 100644
index 0000000..fd4d40b
--- /dev/null
+++ b/spaghetti-monster/fsm-ramping.h
@@ -0,0 +1,26 @@
+/*
+ * fsm-ramping.h: Ramping functions for SpaghettiMonster.
+ * Handles 1- to 4-channel smooth ramping on a single LED.
+ *
+ * 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/>.
+ */
+
+// TODO: ramp tables
+// TODO: RAMP_SIZE / MAX_LVL
+// TODO: actual_lvl
+// TODO: target_lvl
+// TODO: set_lvl
+// TODO: set_lvl_smooth
diff --git a/spaghetti-monster/momentary.c b/spaghetti-monster/momentary.c
new file mode 100644
index 0000000..bb74795
--- /dev/null
+++ b/spaghetti-monster/momentary.c
@@ -0,0 +1,85 @@
+/*
+ * Momentary: Very simple example UI for SpaghettiMonster.
+ * Is intended to be the simplest possible FSM e-switch UI.
+ * The light is on while the button is held; off otherwise.
+ *
+ * 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/>.
+ */
+
+#define FSM_EMISAR_D4_LAYOUT
+#define USE_LVP
+#define USE_DEBUG_BLINK
+#include "spaghetti-monster.h"
+
+volatile uint8_t brightness;
+volatile uint8_t on_now;
+
+void light_on() {
+    on_now = 1;
+    PWM1_LVL = brightness;
+    PWM2_LVL = 0;
+}
+
+void light_off() {
+    on_now = 0;
+    PWM1_LVL = 0;
+    PWM2_LVL = 0;
+}
+
+uint8_t momentary_state(EventPtr event, uint16_t arg) {
+
+    if (event == EV_click1_press) {
+        brightness = 255;
+        light_on();
+        // don't attempt to parse multiple clicks
+        empty_event_sequence();
+        return 0;
+    }
+
+    else if (event == EV_release) {
+        light_off();
+        // don't attempt to parse multiple clicks
+        empty_event_sequence();
+        return 0;
+    }
+
+    else if (event == EV_debug) {
+        //PWM1_LVL = arg&0xff;
+        DEBUG_FLASH;
+        return 0;
+    }
+
+    // event not handled
+    return 1;
+}
+
+// LVP / low-voltage protection
+void low_voltage() {
+    debug_blink(3);
+    if (brightness > 0) {
+        brightness >>= 1;
+        if (on_now) light_on();
+    } else {
+        light_off();
+        standby_mode();
+    }
+}
+
+void setup() {
+    debug_blink(2);
+
+    push_state(momentary_state);
+}
diff --git a/spaghetti-monster/spaghetti-monster.h b/spaghetti-monster/spaghetti-monster.h
new file mode 100644
index 0000000..af6d828
--- /dev/null
+++ b/spaghetti-monster/spaghetti-monster.h
@@ -0,0 +1,737 @@
+/*
+ * SpaghettiMonster: Generic foundation code for e-switch flashlights.
+ * Other possible names:
+ * - FSM
+ * - RoundTable
+ * - Mostly Harmless
+ * - ...
+ *
+ * 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/>.
+ */
+
+#include "tk-attiny.h"
+
+#include <avr/pgmspace.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/wdt.h>
+#include <avr/eeprom.h>
+#include <avr/sleep.h>
+#include <util/delay_basic.h>
+
+// typedefs
+typedef PROGMEM const uint8_t Event;
+typedef Event * EventPtr;
+typedef uint8_t (*EventCallbackPtr)(EventPtr event, uint16_t arg);
+typedef uint8_t EventCallback(EventPtr event, uint16_t arg);
+typedef uint8_t State(EventPtr event, uint16_t arg);
+typedef State * StatePtr;
+typedef struct Emission {
+    EventPtr event;
+    uint16_t arg;
+} Emission;
+
+volatile StatePtr current_state;
+#define EV_MAX_LEN 16
+uint8_t current_event[EV_MAX_LEN];
+// at 0.016 ms per tick, 255 ticks = 4.08 s
+// TODO: 16 bits?
+static volatile uint8_t ticks_since_last_event = 0;
+
+#ifdef USE_LVP
+// volts * 10
+#define VOLTAGE_LOW 30
+// MCU sees voltage 0.X volts lower than actual, add X to readings
+#define VOLTAGE_FUDGE_FACTOR 2
+volatile uint8_t voltage;
+void low_voltage();
+#endif
+#ifdef USE_THERMAL_REGULATION
+volatile int16_t temperature;
+void low_temperature();
+void high_temperature();
+#endif
+
+#ifdef USE_DEBUG_BLINK
+#define OWN_DELAY
+#define USE_DELAY_4MS
+#include "tk-delay.h"
+#define DEBUG_FLASH PWM1_LVL = 64; delay_4ms(2); PWM1_LVL = 0;
+void debug_blink(uint8_t num) {
+    for(; num>0; num--) {
+        PWM1_LVL = 32;
+        delay_4ms(100/4);
+        PWM1_LVL = 0;
+        delay_4ms(100/4);
+    }
+}
+#endif
+
+#define A_ENTER_STATE     1
+#define A_LEAVE_STATE     2
+#define A_TICK            3
+#define A_PRESS           4
+#define A_HOLD_START      5
+#define A_HOLD_TICK       6
+#define A_RELEASE         7
+#define A_RELEASE_TIMEOUT 8
+// TODO: add events for over/under-heat conditions (with parameter for severity)
+#define A_OVERHEATING     9
+#define A_UNDERHEATING    10
+// TODO: add events for low voltage conditions
+#define A_VOLTAGE_LOW     11
+//#define A_VOLTAGE_CRITICAL 12
+#define A_DEBUG           255  // test event for debugging
+
+// TODO: maybe compare events by number instead of pointer?
+//       (number = index in event types array)
+//       (comparison would use full event content, but send off index to callbacks)
+//       (saves space by using uint8_t instead of a pointer)
+//       (also eliminates the need to duplicate single-entry events like for voltage or timer tick)
+
+// Event types
+Event EV_debug[] = {
+    A_DEBUG,
+    0 } ;
+Event EV_enter_state[] = {
+    A_ENTER_STATE,
+    0 } ;
+Event EV_leave_state[] = {
+    A_LEAVE_STATE,
+    0 } ;
+Event EV_tick[] = {
+    A_TICK,
+    0 } ;
+#ifdef USE_LVP
+Event EV_voltage_low[] = {
+    A_VOLTAGE_LOW,
+    0 } ;
+#endif
+#ifdef USE_THERMAL_REGULATION
+Event EV_temperature_high[] = {
+    A_OVERHEATING,
+    0 } ;
+Event EV_temperature_low[] = {
+    A_UNDERHEATING,
+    0 } ;
+#endif
+Event EV_click1_press[] = {
+    A_PRESS,
+    0 };
+// shouldn't normally happen, but UI might reset event while button is down
+// so a release with no recorded prior hold could be possible
+Event EV_release[] = {
+    A_RELEASE,
+    0 };
+Event EV_click1_release[] = {
+    A_PRESS,
+    A_RELEASE,
+    0 };
+#define EV_1click EV_click1_complete
+Event EV_click1_complete[] = {
+    A_PRESS,
+    A_RELEASE,
+    A_RELEASE_TIMEOUT,
+    0 };
+#define EV_hold EV_click1_hold
+// FIXME: Should holds use "start+tick" or just "tick" with a tick number?
+//        Or "start+tick" with a tick number?
+Event EV_click1_hold[] = {
+    A_PRESS,
+    A_HOLD_START,
+    0 };
+Event EV_click1_hold_release[] = {
+    A_PRESS,
+    A_HOLD_START,
+    A_RELEASE,
+    0 };
+Event EV_click2_press[] = {
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    0 };
+Event EV_click2_release[] = {
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    A_RELEASE,
+    0 };
+#define EV_2clicks EV_click2_complete
+Event EV_click2_complete[] = {
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    A_RELEASE,
+    A_RELEASE_TIMEOUT,
+    0 };
+Event EV_click3_press[] = {
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    0 };
+Event EV_click3_release[] = {
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    A_RELEASE,
+    0 };
+#define EV_3clicks EV_click3_complete
+Event EV_click3_complete[] = {
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    A_RELEASE,
+    A_PRESS,
+    A_RELEASE,
+    A_RELEASE_TIMEOUT,
+    0 };
+// ... and so on
+
+// A list of event types for easy iteration
+EventPtr event_sequences[] = {
+    EV_click1_press,
+    EV_release,
+    EV_click1_release,
+    EV_click1_complete,
+    EV_click1_hold,
+    EV_click1_hold_release,
+    EV_click2_press,
+    EV_click2_release,
+    EV_click2_complete,
+    EV_click3_press,
+    EV_click3_release,
+    EV_click3_complete,
+    // ...
+};
+
+#define events_match(a,b) compare_event_sequences(a,b)
+// return 1 if (a == b), 0 otherwise
+uint8_t compare_event_sequences(uint8_t *a, const uint8_t *b) {
+    for(uint8_t i=0; (i<EV_MAX_LEN) && (a[i] == pgm_read_byte(b+i)); i++) {
+        // end of zero-terminated sequence
+        if (a[i] == 0) return 1;
+    }
+    // if we ever fall out, that means something was different
+    // (or the sequence is too long)
+    return 0;
+}
+
+void empty_event_sequence() {
+    for(uint8_t i=0; i<EV_MAX_LEN; i++) current_event[i] = 0;
+}
+
+void push_event(uint8_t ev_type) {
+    ticks_since_last_event = 0;  // something happened
+    uint8_t i;
+    for(i=0; current_event[i] && (i<EV_MAX_LEN); i++);
+    if (i < EV_MAX_LEN) {
+        current_event[i] = ev_type;
+    } else {
+        // TODO: ... something?
+    }
+}
+
+#define EMISSION_QUEUE_LEN 8
+// no comment about "volatile emissions"
+volatile Emission emissions[EMISSION_QUEUE_LEN];
+
+void append_emission(EventPtr event, uint16_t arg) {
+    uint8_t i;
+    // find last entry
+    for(i=0;
+        (i<EMISSION_QUEUE_LEN) && (emissions[i].event != NULL);
+        i++) { }
+    // add new entry
+    if (i < EMISSION_QUEUE_LEN) {
+        emissions[i].event = event;
+        emissions[i].arg = arg;
+    } else {
+        // TODO: if queue full, what should we do?
+    }
+}
+
+void delete_first_emission() {
+    uint8_t i;
+    for(i=0; i<EMISSION_QUEUE_LEN-1; i++) {
+        emissions[i].event = emissions[i+1].event;
+        emissions[i].arg = emissions[i+1].arg;
+    }
+    emissions[i].event = NULL;
+    emissions[i].arg = 0;
+}
+
+// TODO: stack for states, to allow shared utility states like "input a number"
+//       and such, which return to the previous state after finishing
+#define STATE_STACK_SIZE 8
+StatePtr state_stack[STATE_STACK_SIZE];
+uint8_t state_stack_len = 0;
+// TODO: if callback doesn't handle current event,
+//       pass event to next state on stack?
+//       Callback return values:
+//       0: event handled normally
+//       1: event not handled
+//       255: error (not sure what this would even mean though, or what difference it would make)
+// TODO: function to call stacked callbacks until one returns "handled"
+// Call stacked callbacks for the given event until one handles it.
+//#define emit_now emit
+uint8_t emit_now(EventPtr event, uint16_t arg) {
+    for(int8_t i=state_stack_len-1; i>=0; i--) {
+        uint8_t err = state_stack[i](event, arg);
+        if (! err) return 0;
+    }
+    return 1;  // event not handled
+}
+
+void emit(EventPtr event, uint16_t arg) {
+    // add this event to the queue for later,
+    // so we won't use too much time during an interrupt
+    append_emission(event, arg);
+}
+
+// Search the pre-defined event list for one matching what the user just did,
+// and emit it if one was found.
+void emit_current_event(uint16_t arg) {
+    //uint8_t err = 1;
+    for (uint8_t i=0; i<(sizeof(event_sequences)/sizeof(EventPtr)); i++) {
+        if (events_match(current_event, event_sequences[i])) {
+            //DEBUG_FLASH;
+            //err = emit(event_sequences[i], arg);
+            //return err;
+            emit(event_sequences[i], arg);
+            return;
+        }
+    }
+    //return err;
+}
+
+void _set_state(StatePtr new_state) {
+    // call old state-exit hook (don't use stack)
+    if (current_state != NULL) current_state(EV_leave_state, 0);
+    // set new state
+    current_state = new_state;
+    // call new state-enter hook (don't use stack)
+    if (new_state != NULL) current_state(EV_enter_state, 0);
+}
+
+int8_t push_state(StatePtr new_state) {
+    if (state_stack_len < STATE_STACK_SIZE) {
+        // TODO: call old state's exit hook?
+        //       new hook for non-exit recursion into child?
+        state_stack[state_stack_len] = new_state;
+        state_stack_len ++;
+        _set_state(new_state);
+        return state_stack_len;
+    } else {
+        // TODO: um...  how is a flashlight supposed to handle a recursion depth error?
+        return -1;
+    }
+}
+
+StatePtr pop_state() {
+    // TODO: how to handle pop from empty stack?
+    StatePtr old_state = NULL;
+    StatePtr new_state = NULL;
+    if (state_stack_len > 0) {
+        state_stack_len --;
+        old_state = state_stack[state_stack_len];
+    }
+    if (state_stack_len > 0) {
+        new_state = state_stack[state_stack_len-1];
+    }
+    _set_state(new_state);
+    return old_state;
+}
+
+uint8_t set_state(StatePtr new_state) {
+    // FIXME: this calls exit/enter hooks it shouldn't
+    pop_state();
+    return push_state(new_state);
+}
+
+// TODO? add events to a queue when inside an interrupt
+//       instead of calling the event functions directly?
+//       (then empty the queue in main loop?)
+
+// TODO? new delay() functions which handle queue consumption?
+// TODO? new interruptible delay() functions?
+
+
+//static volatile uint8_t button_was_pressed;
+#define BP_SAMPLES 16
+uint8_t button_is_pressed() {
+    // debounce a little
+    uint8_t highcount = 0;
+    // measure for 16/64ths of a ms
+    for(uint8_t i=0; i<BP_SAMPLES; i++) {
+        // check current value
+        uint8_t bit = ((PINB & (1<<SWITCH_PIN)) == 0);
+        highcount += bit;
+        // wait a moment
+        _delay_loop_2(BOGOMIPS/64);
+    }
+    // use most common value
+    uint8_t result = (highcount > (BP_SAMPLES/2));
+    //button_was_pressed = result;
+    return result;
+}
+
+//void button_change_interrupt() {
+ISR(PCINT0_vect) {
+
+    //DEBUG_FLASH;
+
+    // something happened
+    //ticks_since_last_event = 0;
+
+    // add event to current sequence
+    if (button_is_pressed()) {
+        push_event(A_PRESS);
+    } else {
+        push_event(A_RELEASE);
+    }
+
+    // check if sequence matches any defined sequences
+    // if so, send event to current state callback
+    emit_current_event(0);
+}
+
+// TODO: implement
+ISR(WDT_vect) {
+    /*
+    // TODO? safety net for PCINT, in case it misses a press or release
+    uint8_t bp = button_is_pressed();
+    if (bp != button_was_pressed) {
+        // TODO: handle missed button event
+        if (bp) {
+            push_event(A_PRESS);
+        } else {
+            push_event(A_RELEASE);
+        }
+        emit_current_event(0);
+    }
+    */
+
+    //timer ++;  // Is this needed at all?
+
+    /*
+    if (ticks_since_last_event & 0b00000111 ) {
+        DEBUG_FLASH;
+    }
+    */
+
+    //if (ticks_since_last_event < 0xff) ticks_since_last_event ++;
+    // increment, but loop from 255 back to 128
+    ticks_since_last_event = (ticks_since_last_event + 1) \
+                             | (ticks_since_last_event & 0x80);
+
+    //static uint8_t hold_ticks = 0;  // TODO: 16 bits?
+
+    // callback on each timer tick
+    emit(EV_tick, ticks_since_last_event);
+
+    // if time since last event exceeds timeout,
+    // append timeout to current event sequence, then
+    // send event to current state callback
+    // //hold_event(ticks)
+    // //emit(EV_press_hold, hold_ticks);
+    // emit_current_event(hold_ticks);
+    // or
+    // //release_timeout()
+    // //emit(EV_press_release_timeout, 0);
+    // emit_current_event(0);
+
+    #if defined(USE_LVP) || defined(USE_THERMAL_REGULATION)
+    // start a new ADC measurement every 4 ticks
+    static uint8_t adc_trigger = 0;
+    adc_trigger ++;
+    if (adc_trigger > 3) {
+        adc_trigger = 0;
+        ADCSRA |= (1 << ADSC) | (1 << ADIE);
+    }
+    #endif
+}
+
+// TODO: implement?  (or is it better done in main()?)
+ISR(ADC_vect) {
+    static uint8_t adc_step = 0;
+    #ifdef USE_LVP
+    #ifdef USE_LVP_AVG
+    #define NUM_VOLTAGE_VALUES 4
+    static int16_t voltage_values[NUM_VOLTAGE_VALUES];
+    #endif
+    static uint8_t lvp_timer = 0;
+    static uint8_t lvp_lowpass = 0;
+    #define LVP_TIMER_START 50  // ticks between LVP warnings
+    #define LVP_LOWPASS_STRENGTH 4
+    #endif
+
+    #ifdef USE_THERMAL_REGULATION
+    #define NUM_THERMAL_VALUES 4
+    #define ADC_STEPS 4
+    static int16_t temperature_values[NUM_THERMAL_VALUES];
+    #else
+    #define ADC_STEPS 2
+    #endif
+
+    uint16_t measurement = ADC;  // latest 10-bit ADC reading
+
+    adc_step = (adc_step + 1) & (ADC_STEPS-1);
+
+    #ifdef USE_LVP
+    // voltage
+    if (adc_step == 1) {
+        #ifdef USE_LVP_AVG
+        // prime on first execution
+        if (voltage == 0) {
+            for(uint8_t i=0; i<NUM_VOLTAGE_VALUES; i++)
+                voltage_values[i] = measurement;
+            voltage = 42;  // Life, the Universe, and Everything (*)
+        } else {
+            uint16_t total = 0;
+            uint8_t i;
+            for(i=0; i<NUM_VOLTAGE_VALUES-1; i++) {
+                voltage_values[i] = voltage_values[i+1];
+                total += voltage_values[i];
+            }
+            voltage_values[i] = measurement;
+            total += measurement;
+            total = total >> 2;
+
+            voltage = (uint16_t)(1.1*1024*10)/total + VOLTAGE_FUDGE_FACTOR;
+        }
+        #else  // no USE_LVP_AVG
+        // calculate actual voltage: volts * 10
+        // ADC = 1.1 * 1024 / volts
+        // volts = 1.1 * 1024 / ADC
+        voltage = (uint16_t)(1.1*1024*10)/measurement + VOLTAGE_FUDGE_FACTOR;
+        #endif
+        // if low, callback EV_voltage_low / EV_voltage_critical
+        //         (but only if it has been more than N ticks since last call)
+        if (lvp_timer) {
+            lvp_timer --;
+        } else {  // it has been long enough since the last warning
+            if (voltage < VOLTAGE_LOW) {
+                if (lvp_lowpass < LVP_LOWPASS_STRENGTH) {
+                    lvp_lowpass ++;
+                } else {
+                    // try to send out a warning
+                    //uint8_t err = emit(EV_voltage_low, 0);
+                    //uint8_t err = emit_now(EV_voltage_low, 0);
+                    emit(EV_voltage_low, 0);
+                    //if (!err) {
+                        // on successful warning, reset counters
+                        lvp_timer = LVP_TIMER_START;
+                        lvp_lowpass = 0;
+                    //}
+                }
+            } else {
+                // voltage not low?  reset count
+                lvp_lowpass = 0;
+            }
+        }
+    }
+    #endif  // ifdef USE_LVP
+
+    // TODO: temperature
+
+    // start another measurement for next time
+    #ifdef USE_THERMAL_REGULATION
+        #ifdef USE_LVP
+        if (adc_step < 2) ADMUX = ADMUX_VCC;
+        else ADMUX = ADMUX_THERM;
+        #else
+        ADMUX = ADMUX_THERM;
+        #endif
+    #else
+        #ifdef USE_LVP
+        ADMUX = ADMUX_VCC;
+        #endif
+    #endif
+}
+
+inline void ADC_on()
+{
+    // read voltage on VCC by default
+    // disable digital input on VCC pin to reduce power consumption
+    //DIDR0 |= (1 << ADC_DIDR);  // FIXME: unsure how to handle for VCC pin
+    // VCC / 1.1V reference
+    ADMUX = ADMUX_VCC;
+    // enable, start, prescale
+    ADCSRA = (1 << ADEN) | (1 << ADSC) | ADC_PRSCL;
+}
+
+inline void ADC_off() {
+    ADCSRA &= ~(1<<ADEN); //ADC off
+}
+
+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 WDT_on()
+{
+    // interrupt every 16ms
+    //cli();                          // Disable interrupts
+    wdt_reset();                    // Reset the WDT
+    WDTCR |= (1<<WDCE) | (1<<WDE);  // Start timed sequence
+    WDTCR = (1<<WDIE);              // Enable interrupt every 16ms
+    //sei();                          // Enable interrupts
+}
+
+inline void WDT_off()
+{
+    //cli();                          // Disable interrupts
+    wdt_reset();                    // Reset the WDT
+    MCUSR &= ~(1<<WDRF);            // Clear Watchdog reset flag
+    WDTCR |= (1<<WDCE) | (1<<WDE);  // Start timed sequence
+    WDTCR = 0x00;                   // Disable WDT
+    //sei();                          // Enable interrupts
+}
+
+// low-power standby mode used while off but power still connected
+#define standby_mode sleep_until_eswitch_pressed
+void sleep_until_eswitch_pressed()
+{
+    WDT_off();
+    ADC_off();
+
+    // make sure switch isn't currently pressed
+    while (button_is_pressed()) {}
+
+    PCINT_on();  // wake on e-switch event
+
+    sleep_enable();
+    sleep_bod_disable();
+    sleep_cpu();  // wait here
+
+    // something happened; wake up
+    sleep_disable();
+    PCINT_on();
+    ADC_on();
+    WDT_on();
+}
+
+// last-called state on stack
+// handles default actions for LVP, thermal regulation, etc
+uint8_t default_state(EventPtr event, uint16_t arg) {
+    if (0) {}
+
+    #ifdef USE_LVP
+    else if (event == EV_voltage_low) {
+        low_voltage();
+        return 0;
+    }
+    #endif
+
+    #ifdef USE_THERMAL_REGULATION
+    else if (event == EV_temperature_high) {
+        high_temperature();
+        return 0;
+    }
+
+    else if (event == EV_temperature_low) {
+        low_temperature();
+        return 0;
+    }
+    #endif
+
+    // event not handled
+    return 1;
+}
+
+// boot-time tasks
+// Define this in your RoundTable recipe
+void setup();
+
+int main() {
+    // Don't allow interrupts while booting
+    cli();
+    //WDT_off();
+    //PCINT_off();
+
+    // configure PWM channels
+    #if PWM_CHANNELS >= 1
+    DDRB |= (1 << PWM1_PIN);
+    TCCR0B = 0x01; // pre-scaler for timer (1 => 1, 2 => 8, 3 => 64...)
+    TCCR0A = PHASE;
+    #elif PWM_CHANNELS >= 2
+    DDRB |= (1 << PWM2_PIN);
+    #elif PWM_CHANNELS >= 3
+    DDRB |= (1 << PWM3_PIN);
+    // Second PWM counter is ... weird
+    TCCR1 = _BV (CS10);
+    GTCCR = _BV (COM1B1) | _BV (PWM1B);
+    OCR1C = 255;  // Set ceiling value to maximum
+    #elif PWM_CHANNELS == 4
+    // FIXME: How exactly do we do PWM on channel 4?
+    DDRB |= (1 << PWM4_PIN);
+    #endif
+
+    // TODO: turn on ADC?
+    // configure e-switch
+    PORTB = (1 << SWITCH_PIN);  // e-switch is the only input
+    PCMSK = (1 << SWITCH_PIN);  // pin change interrupt uses this pin
+
+    // TODO: configure sleep mode
+    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+
+    // Read config values and saved state
+    // restore_state();  // TODO
+
+    // TODO: handle long press vs short press (or even medium press)?
+
+    #ifdef USE_DEBUG_BLINK
+    //debug_blink(1);
+    #endif
+
+    // all booted -- turn interrupts back on
+    PCINT_on();
+    WDT_on();
+    ADC_on();
+    sei();
+
+    // fallback for handling a few things
+    push_state(default_state);
+
+    // call recipe's setup
+    setup();
+
+    // main loop
+    while (1) {
+        // TODO: update e-switch press state?
+        // TODO: check voltage?
+        // TODO: check temperature?
+        // if event queue not empty, process and pop first item in queue?
+        if (emissions[0].event != NULL) {
+            emit_now(emissions[0].event, emissions[0].arg);
+            delete_first_emission();
+        }
+    }
+}
-- 
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