merged irq-refactor branch, which fixes some small but long-standing issues:

- occasional missed button events while asleep
- occasional short/aborted frames in aux LED sleep animation
- rare case of bogus voltage and/or temperature values
- fixed issue where nice_delay_ms() didn't work in setup()
- fixed theoretical possibility of extra-noisy buttons causing a hang

Also does some other things:
- cleans up the ADC code significantly
- adds a voltage stabilizer/lowpass option (enabled on t1634 builds)
- greatly reduces time spent per interrupt,
  which might make a future PWM-DSM technique possible
- moves most interrupt-handling logic to a non-critical code path,
  deferring that code until timing doesn't matter as much
- sped up button state measurements
- turned off muggle mode on a couple builds which were too big

16 files changed, 353 insertions, 266 deletions

diff --git a/spaghetti-monster/anduril/anduril.c b/spaghetti-monster/anduril/anduril.c
index 48f4ac1..19d61b7 100644
--- a/spaghetti-monster/anduril/anduril.c
+++ b/spaghetti-monster/anduril/anduril.c
@@ -2356,7 +2356,7 @@ void rgb_led_update(uint8_t mode, uint8_t arg) {
 void factory_reset() {
     // display a warning for a few seconds before doing the actual reset,
     // so the user has time to abort if they want
-    #define SPLODEY_TIME 3000
+    #define SPLODEY_TIME 2500
     #define SPLODEY_STEPS 64
     #define SPLODEY_TIME_PER_STEP (SPLODEY_TIME/SPLODEY_STEPS)
     uint8_t bright;
@@ -2364,9 +2364,9 @@ void factory_reset() {
     // wind up to an explosion
     for (bright=0; bright<SPLODEY_STEPS; bright++) {
         set_level(bright);
-        delay_4ms(SPLODEY_TIME_PER_STEP/2/4);
+        nice_delay_ms(SPLODEY_TIME_PER_STEP/2);
         set_level(bright>>1);
-        delay_4ms(SPLODEY_TIME_PER_STEP/2/4);
+        nice_delay_ms(SPLODEY_TIME_PER_STEP/2);
         if (! button_is_pressed()) {
             reset = 0;
             break;
@@ -2387,14 +2387,14 @@ void factory_reset() {
         bright = MAX_LEVEL;
         for (; bright > 0; bright--) {
             set_level(bright);
-            delay_4ms(SPLODEY_TIME_PER_STEP/6/4);
+            nice_delay_ms(SPLODEY_TIME_PER_STEP/8);
         }
     }
     // explosion cancelled, fade away
     else {
         for (; bright > 0; bright--) {
             set_level(bright);
-            delay_4ms(SPLODEY_TIME_PER_STEP/3/4);
+            nice_delay_ms(SPLODEY_TIME_PER_STEP/3);
         }
     }
 }
diff --git a/spaghetti-monster/anduril/cfg-blf-q8.h b/spaghetti-monster/anduril/cfg-blf-q8.h
index 970fedb..166b10e 100644
--- a/spaghetti-monster/anduril/cfg-blf-q8.h
+++ b/spaghetti-monster/anduril/cfg-blf-q8.h
@@ -13,6 +13,11 @@
 // lockout: blinking (3)
 #define INDICATOR_LED_DEFAULT_MODE ((3<<2) + 2)
 
+// doesn't quite fit
+#ifdef USE_MUGGLE_MODE
+#undef USE_MUGGLE_MODE
+#endif
+
 // copied from Emisar D4 ramp
 // ../../bin/level_calc.py 1 65 7135 1 0.8 150
 // ... mixed with this:
diff --git a/spaghetti-monster/anduril/cfg-emisar-d4s.h b/spaghetti-monster/anduril/cfg-emisar-d4s.h
index 230ac7c..6fe95a6 100644
--- a/spaghetti-monster/anduril/cfg-emisar-d4s.h
+++ b/spaghetti-monster/anduril/cfg-emisar-d4s.h
@@ -46,3 +46,4 @@
 #define THERMAL_WARNING_SECONDS 3
 #define THERMAL_UPDATE_SPEED 2
 #define THERM_PREDICTION_STRENGTH 4
+
diff --git a/spaghetti-monster/anduril/cfg-emisar-d4sv2.h b/spaghetti-monster/anduril/cfg-emisar-d4sv2.h
index acc9101..c47e774 100644
--- a/spaghetti-monster/anduril/cfg-emisar-d4sv2.h
+++ b/spaghetti-monster/anduril/cfg-emisar-d4sv2.h
@@ -61,3 +61,7 @@
 
 // seems relevant on attiny1634
 #define THERM_CAL_OFFSET 5
+
+// attiny1634 has enough space to smooth out voltage readings
+#define USE_VOLTAGE_LOWPASS
+
diff --git a/spaghetti-monster/anduril/cfg-emisar-d4v2.h b/spaghetti-monster/anduril/cfg-emisar-d4v2.h
index b83c65c..0db1062 100644
--- a/spaghetti-monster/anduril/cfg-emisar-d4v2.h
+++ b/spaghetti-monster/anduril/cfg-emisar-d4v2.h
@@ -49,3 +49,6 @@
 #define USE_TENCLICK_THERMAL_CONFIG
 
 #define THERM_CAL_OFFSET 5
+
+// attiny1634 has enough space to smooth out voltage readings
+#define USE_VOLTAGE_LOWPASS
diff --git a/spaghetti-monster/anduril/cfg-mateminco-mf01s.h b/spaghetti-monster/anduril/cfg-mateminco-mf01s.h
index 0585b38..2af1305 100644
--- a/spaghetti-monster/anduril/cfg-mateminco-mf01s.h
+++ b/spaghetti-monster/anduril/cfg-mateminco-mf01s.h
@@ -14,6 +14,12 @@
 #define INDICATOR_LED_DEFAULT_MODE ((3<<2) + 1)
 
 
+// doesn't quite fit
+#ifdef USE_MUGGLE_MODE
+#undef USE_MUGGLE_MODE
+#endif
+
+
 // don't blink during ramp, it's irrelevant and annoying on this light
 #define BLINK_AT_RAMP_CEILING
 #undef BLINK_AT_RAMP_MIDDLE
diff --git a/spaghetti-monster/fsm-adc.c b/spaghetti-monster/fsm-adc.c
index 6832e32..c859539 100644
--- a/spaghetti-monster/fsm-adc.c
+++ b/spaghetti-monster/fsm-adc.c
@@ -30,6 +30,7 @@ inline void set_admux_therm() {
     #else
         #error Unrecognized MCU type
     #endif
+    adc_channel = 1;
 }
 
 inline void set_admux_voltage() {
@@ -52,6 +53,7 @@ inline void set_admux_voltage() {
     #else
         #error Unrecognized MCU type
     #endif
+    adc_channel = 0;
 }
 
 inline void ADC_start_measurement() {
@@ -113,36 +115,158 @@ static inline uint8_t calc_voltage_divider(uint16_t value) {
 #else
 #define ADC_CYCLES_PER_SECOND 8
 #endif
-// TODO: is this better done in main() or WDT()?
+
+#ifdef USE_THERMAL_REGULATION
+#define ADC_STEPS 2
+#else
+#define ADC_STEPS 1
+#endif
+
+// happens every time the ADC sampler finishes a measurement
 ISR(ADC_vect) {
-    // For some reason, the ADC interrupt is getting called a *lot*
-    // more often than it should be, like it's auto-triggering after each
-    // measurement, but I don't know why, or how to turn that off...
-    // So, skip every call except when explicitly requested.
+    #ifdef USE_PSEUDO_RAND
+    // real-world entropy makes this a true random, not pseudo
+    pseudo_rand_seed += ADCL;
+    #endif
+
+    if (irq_adc_stable) {  // skip first result; it's junk
+        adc_values[adc_channel] = ADC;  // save this for later use
+        irq_adc = 1;  // a value was saved, so trigger deferred logic
+    }
+    irq_adc_stable = 1;
+
+    // start another measurement
+    // (is explicit because it otherwise doesn't seem to happen during standby mode)
+    ADC_start_measurement();
+}
+
+void ADC_inner() {
+    irq_adc = 0;  // event handled
+
+    // the ADC triggers repeatedly when it's on, but we only want one value
+    // (so ignore everything after the first value, until it's manually reset)
     if (! adcint_enable) return;
+
+    // disable after one iteration
     adcint_enable = 0;
 
+    #ifdef TICK_DURING_STANDBY
+        // in sleep mode, turn off after just one measurement
+        // (having the ADC on raises standby power by about 250 uA)
+        // (and the usual standby level is only ~20 uA)
+        if (go_to_standby) ADC_off();
+    #endif
+
+    // what is being measured? 0 = battery voltage, 1 = temperature
     static uint8_t adc_step = 0;
 
-    // LVP declarations
     #ifdef USE_LVP
-    #ifdef USE_LVP_AVG
-    #define NUM_VOLTAGE_VALUES 4
-    static int16_t voltage_values[NUM_VOLTAGE_VALUES];
+    if (0 == adc_step) {  // voltage
+        ADC_voltage_handler();
+    }
+    #endif
+
+    #ifdef USE_THERMAL_REGULATION
+    else if (1 == adc_step) {  // temperature
+        ADC_temperature_handler();
+    }
+    #endif
+
+    #if defined(TICK_DURING_STANDBY) && defined(USE_SLEEP_LVP)
+    // only measure battery voltage while asleep
+    if (go_to_standby) adc_step = 0;
+    else
+    #endif
+
+    adc_step = (adc_step + 1) & (ADC_STEPS-1);
+
+    // set the correct type of measurement for next time
+    #ifdef USE_THERMAL_REGULATION
+        #ifdef USE_LVP
+        if (0 == adc_step) set_admux_voltage();
+        else set_admux_therm();
+        #else
+        //set_admux_therm();
+        #error "USE_THERMAL_REGULATION set without USE_LVP"
+        #endif
+    #else
+        #ifdef USE_LVP
+        set_admux_voltage();
+        #endif
     #endif
+
+    irq_adc_stable = 0;  // first result is unstable
+}
+
+
+#ifdef USE_LVP
+static inline void ADC_voltage_handler() {
     static uint8_t lvp_timer = 0;
     static uint8_t lvp_lowpass = 0;
     #define LVP_TIMER_START (VOLTAGE_WARNING_SECONDS*ADC_CYCLES_PER_SECOND)  // N seconds between LVP warnings
     #define LVP_LOWPASS_STRENGTH ADC_CYCLES_PER_SECOND  // lowpass for one second
+
+    uint16_t measurement = adc_values[0];  // latest 10-bit ADC reading
+
+    #ifdef USE_VOLTAGE_LOWPASS
+        static uint16_t prev_measurement = 0;
+
+        // prime on first execution, or while asleep
+        if (go_to_standby || (! prev_measurement)) prev_measurement = measurement;
+
+        // only allow raw value to go up or down by 1 per iteration
+        if (measurement > prev_measurement) measurement = prev_measurement + 1;
+        else if (measurement < prev_measurement) measurement = prev_measurement - 1;
+
+        // remember for later
+        prev_measurement = measurement;
+    #endif  // no USE_VOLTAGE_LOWPASS
+
+    #ifdef USE_VOLTAGE_DIVIDER
+    voltage = calc_voltage_divider(measurement);
+    #else
+    // 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;
+    voltage = ((uint16_t)(2*1.1*1024*10)/measurement + VOLTAGE_FUDGE_FACTOR) >> 1;
     #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_THERMAL_REGULATION
+static inline void ADC_temperature_handler() {
     // thermal declarations
-    #ifdef USE_THERMAL_REGULATION
     #ifndef THERMAL_UPDATE_SPEED
     #define THERMAL_UPDATE_SPEED 2
     #endif
     #define NUM_THERMAL_VALUES_HISTORY 8
-    #define ADC_STEPS 4
     static uint8_t history_step = 0;  // don't update history as often
     static int16_t temperature_history[NUM_THERMAL_VALUES_HISTORY];
     static uint8_t temperature_timer = 0;
@@ -151,236 +275,132 @@ ISR(ADC_vect) {
     #define TEMPERATURE_TIMER_START ((THERMAL_WARNING_SECONDS-2)*ADC_CYCLES_PER_SECOND)  // N seconds between thermal regulation events
     #define OVERHEAT_LOWPASS_STRENGTH (ADC_CYCLES_PER_SECOND*2)  // lowpass for 2 seconds
     #define UNDERHEAT_LOWPASS_STRENGTH (ADC_CYCLES_PER_SECOND*2)  // lowpass for 2 seconds
-    #else
-    #define ADC_STEPS 2
-    #endif
-
-    uint16_t measurement = ADC;  // latest 10-bit ADC reading
-
-    #ifdef USE_PSEUDO_RAND
-    // real-world entropy makes this a true random, not pseudo
-    pseudo_rand_seed += measurement;
-    #endif
-
-    #if defined(TICK_DURING_STANDBY) && defined(USE_SLEEP_LVP)
-    // only measure battery voltage while asleep
-    if (go_to_standby) adc_step = 1;
-    else
-    #endif
 
-    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;  // the answer to life, the universe, and the voltage of a full li-ion cell
-        } 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;
-
-            #ifdef USE_VOLTAGE_DIVIDER
-            voltage = calc_voltage_divider(total);
-            #else
-            voltage = (uint16_t)(1.1*1024*10)/total + VOLTAGE_FUDGE_FACTOR;
-            #endif
-        }
-        #else  // no USE_LVP_AVG
-            #ifdef USE_VOLTAGE_DIVIDER
-            voltage = calc_voltage_divider(measurement);
-            #else
-            // 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;
-            voltage = ((uint16_t)(2*1.1*1024*10)/measurement + VOLTAGE_FUDGE_FACTOR) >> 1;
-            #endif
-        #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;
-            }
+    uint16_t measurement = adc_values[1];  // latest 10-bit ADC reading
+
+    // Convert ADC units to Celsius (ish)
+    int16_t temp = measurement - 275 + THERM_CAL_OFFSET + (int16_t)therm_cal_offset;
+
+    // prime on first execution
+    if (reset_thermal_history) {
+        reset_thermal_history = 0;
+        temperature = temp;
+        for(uint8_t i=0; i<NUM_THERMAL_VALUES_HISTORY; i++)
+            temperature_history[i] = temp;
+    } else {  // update our current temperature estimate
+        // crude lowpass filter
+        // (limit rate of change to 1 degree per measurement)
+        if (temp > temperature) {
+            temperature ++;
+        } else if (temp < temperature) {
+            temperature --;
         }
     }
-    #endif  // ifdef USE_LVP
 
+    // guess what the temperature will be in a few seconds
+    int16_t pt;
+    {
+        int16_t diff;
+        int16_t t = temperature;
 
-    #ifdef USE_THERMAL_REGULATION
-    // temperature
-    else if (adc_step == 3) {
-        // Convert ADC units to Celsius (ish)
-        int16_t temp = measurement - 275 + THERM_CAL_OFFSET + (int16_t)therm_cal_offset;
-
-        // prime on first execution
-        if (reset_thermal_history) {
-            reset_thermal_history = 0;
-            temperature = temp;
-            for(uint8_t i=0; i<NUM_THERMAL_VALUES_HISTORY; i++)
-                temperature_history[i] = temp;
-        } else {  // update our current temperature estimate
-            // crude lowpass filter
-            // (limit rate of change to 1 degree per measurement)
-            if (temp > temperature) {
-                temperature ++;
-            } else if (temp < temperature) {
-                temperature --;
+        // algorithm tweaking; not really intended to be modified
+        // how far ahead should we predict?
+        #ifndef THERM_PREDICTION_STRENGTH
+        #define THERM_PREDICTION_STRENGTH 4
+        #endif
+        // how proportional should the adjustments be?  (not used yet)
+        #ifndef THERM_RESPONSE_MAGNITUDE
+        #define THERM_RESPONSE_MAGNITUDE 128
+        #endif
+        // acceptable temperature window size in C
+        #define THERM_WINDOW_SIZE 5
+        // highest temperature allowed
+        #define THERM_CEIL ((int16_t)therm_ceil)
+        // bottom of target temperature window
+        #define THERM_FLOOR (THERM_CEIL - THERM_WINDOW_SIZE)
+
+        // if it's time to rotate the thermal history, do it
+        history_step ++;
+        #if (THERMAL_UPDATE_SPEED == 4)  // new value every 4s
+        #define THERM_HISTORY_STEP_MAX 15
+        #elif (THERMAL_UPDATE_SPEED == 2)  // new value every 2s
+        #define THERM_HISTORY_STEP_MAX 7
+        #elif (THERMAL_UPDATE_SPEED == 1)  // new value every 1s
+        #define THERM_HISTORY_STEP_MAX 3
+        #elif (THERMAL_UPDATE_SPEED == 0)  // new value every 0.5s
+        #define THERM_HISTORY_STEP_MAX 1
+        #endif
+        if (0 == (history_step & THERM_HISTORY_STEP_MAX)) {
+            // rotate measurements and add a new one
+            for (uint8_t i=0; i<NUM_THERMAL_VALUES_HISTORY-1; i++) {
+                temperature_history[i] = temperature_history[i+1];
             }
+            temperature_history[NUM_THERMAL_VALUES_HISTORY-1] = t;
         }
 
-        // guess what the temperature will be in a few seconds
-        int16_t pt;
-        {
-            int16_t diff;
-            int16_t t = temperature;
-
-            // algorithm tweaking; not really intended to be modified
-            // how far ahead should we predict?
-            #ifndef THERM_PREDICTION_STRENGTH
-            #define THERM_PREDICTION_STRENGTH 4
-            #endif
-            // how proportional should the adjustments be?  (not used yet)
-            #ifndef THERM_RESPONSE_MAGNITUDE
-            #define THERM_RESPONSE_MAGNITUDE 128
-            #endif
-            // acceptable temperature window size in C
-            #define THERM_WINDOW_SIZE 5
-            // highest temperature allowed
-            #define THERM_CEIL ((int16_t)therm_ceil)
-            // bottom of target temperature window
-            #define THERM_FLOOR (THERM_CEIL - THERM_WINDOW_SIZE)
-
-            // if it's time to rotate the thermal history, do it
-            history_step ++;
-            #if (THERMAL_UPDATE_SPEED == 4)  // new value every 4s
-            #define THERM_HISTORY_STEP_MAX 15
-            #elif (THERMAL_UPDATE_SPEED == 2)  // new value every 2s
-            #define THERM_HISTORY_STEP_MAX 7
-            #elif (THERMAL_UPDATE_SPEED == 1)  // new value every 1s
-            #define THERM_HISTORY_STEP_MAX 3
-            #elif (THERMAL_UPDATE_SPEED == 0)  // new value every 0.5s
-            #define THERM_HISTORY_STEP_MAX 1
-            #endif
-            if (0 == (history_step & THERM_HISTORY_STEP_MAX)) {
-                // rotate measurements and add a new one
-                for (uint8_t i=0; i<NUM_THERMAL_VALUES_HISTORY-1; i++) {
-                    temperature_history[i] = temperature_history[i+1];
-                }
-                temperature_history[NUM_THERMAL_VALUES_HISTORY-1] = t;
-            }
-
-            // guess what the temp will be several seconds in the future
-            // diff = rate of temperature change
-            //diff = temperature_history[NUM_THERMAL_VALUES_HISTORY-1] - temperature_history[0];
-            diff = t - temperature_history[0];
-            // slight bias toward zero; ignore very small changes (noise)
-            for (uint8_t z=0; z<3; z++) {
-                if (diff < 0) diff ++;
-                if (diff > 0) diff --;
-            }
-            // projected_temperature = current temp extended forward by amplified rate of change
-            //projected_temperature = temperature_history[NUM_THERMAL_VALUES_HISTORY-1] + (diff<<THERM_PREDICTION_STRENGTH);
-            pt = projected_temperature = t + (diff<<THERM_PREDICTION_STRENGTH);
+        // guess what the temp will be several seconds in the future
+        // diff = rate of temperature change
+        //diff = temperature_history[NUM_THERMAL_VALUES_HISTORY-1] - temperature_history[0];
+        diff = t - temperature_history[0];
+        // slight bias toward zero; ignore very small changes (noise)
+        for (uint8_t z=0; z<3; z++) {
+            if (diff < 0) diff ++;
+            if (diff > 0) diff --;
         }
+        // projected_temperature = current temp extended forward by amplified rate of change
+        //projected_temperature = temperature_history[NUM_THERMAL_VALUES_HISTORY-1] + (diff<<THERM_PREDICTION_STRENGTH);
+        pt = projected_temperature = t + (diff<<THERM_PREDICTION_STRENGTH);
+    }
 
-        // cancel counters if appropriate
-        if (pt > THERM_FLOOR) {
-            underheat_lowpass = 0;  // we're probably not too cold
-        }
-        if (pt < THERM_CEIL) {
-            overheat_lowpass = 0;  // we're probably not too hot
-        }
+    // cancel counters if appropriate
+    if (pt > THERM_FLOOR) {
+        underheat_lowpass = 0;  // we're probably not too cold
+    }
+    if (pt < THERM_CEIL) {
+        overheat_lowpass = 0;  // we're probably not too hot
+    }
 
-        if (temperature_timer) {
-            temperature_timer --;
-        } else {  // it has been long enough since the last warning
-
-            // Too hot?
-            if (pt > THERM_CEIL) {
-                if (overheat_lowpass < OVERHEAT_LOWPASS_STRENGTH) {
-                    overheat_lowpass ++;
-                } else {
-                    // reset counters
-                    overheat_lowpass = 0;
-                    temperature_timer = TEMPERATURE_TIMER_START;
-                    // how far above the ceiling?
-                    //int16_t howmuch = (pt - THERM_CEIL) * THERM_RESPONSE_MAGNITUDE / 128;
-                    int16_t howmuch = pt - THERM_CEIL;
-                    // try to send out a warning
-                    emit(EV_temperature_high, howmuch);
-                }
+    if (temperature_timer) {
+        temperature_timer --;
+    } else {  // it has been long enough since the last warning
+
+        // Too hot?
+        if (pt > THERM_CEIL) {
+            if (overheat_lowpass < OVERHEAT_LOWPASS_STRENGTH) {
+                overheat_lowpass ++;
+            } else {
+                // reset counters
+                overheat_lowpass = 0;
+                temperature_timer = TEMPERATURE_TIMER_START;
+                // how far above the ceiling?
+                //int16_t howmuch = (pt - THERM_CEIL) * THERM_RESPONSE_MAGNITUDE / 128;
+                int16_t howmuch = pt - THERM_CEIL;
+                // try to send out a warning
+                emit(EV_temperature_high, howmuch);
             }
+        }
 
-            // Too cold?
-            else if (pt < THERM_FLOOR) {
-                if (underheat_lowpass < UNDERHEAT_LOWPASS_STRENGTH) {
-                    underheat_lowpass ++;
-                } else {
-                    // reset counters
-                    underheat_lowpass = 0;
-                    temperature_timer = TEMPERATURE_TIMER_START;
-                    // how far below the floor?
-                    //int16_t howmuch = (THERM_FLOOR - pt) * THERM_RESPONSE_MAGNITUDE / 128;
-                    int16_t howmuch = THERM_FLOOR - pt;
-                    // try to send out a warning (unless voltage is low)
-                    // (LVP and underheat warnings fight each other)
-                    if (voltage > VOLTAGE_LOW)
-                        emit(EV_temperature_low, howmuch);
-                }
+        // Too cold?
+        else if (pt < THERM_FLOOR) {
+            if (underheat_lowpass < UNDERHEAT_LOWPASS_STRENGTH) {
+                underheat_lowpass ++;
+            } else {
+                // reset counters
+                underheat_lowpass = 0;
+                temperature_timer = TEMPERATURE_TIMER_START;
+                // how far below the floor?
+                //int16_t howmuch = (THERM_FLOOR - pt) * THERM_RESPONSE_MAGNITUDE / 128;
+                int16_t howmuch = THERM_FLOOR - pt;
+                // try to send out a warning (unless voltage is low)
+                // (LVP and underheat warnings fight each other)
+                if (voltage > VOLTAGE_LOW)
+                    emit(EV_temperature_low, howmuch);
             }
         }
     }
-    #endif  // ifdef USE_THERMAL_REGULATION
-
-
-    // set the correct type of measurement for next time
-    #ifdef USE_THERMAL_REGULATION
-        #ifdef USE_LVP
-        if (adc_step < 2) set_admux_voltage();
-        else set_admux_therm();
-        #else
-        set_admux_therm();
-        #endif
-    #else
-        #ifdef USE_LVP
-        set_admux_voltage();
-        #endif
-    #endif
-
-    #ifdef TICK_DURING_STANDBY
-        // if we were asleep, go back to sleep
-        if (go_to_standby) ADC_off();
-    #endif
 }
+#endif
+
 
 #ifdef USE_BATTCHECK
 #ifdef BATTCHECK_4bars
diff --git a/spaghetti-monster/fsm-adc.h b/spaghetti-monster/fsm-adc.h
index 274fb4d..6e39750 100644
--- a/spaghetti-monster/fsm-adc.h
+++ b/spaghetti-monster/fsm-adc.h
@@ -38,9 +38,18 @@
 #define VOLTAGE_FUDGE_FACTOR 5
 #endif
 #endif
+
+volatile uint8_t irq_adc = 0;  // ADC interrupt happened?
+volatile uint8_t irq_adc_stable = 0;  // have we passed the 1st junk value yet?
+uint8_t adc_channel = 0;  // 0=voltage, 1=temperature
+uint16_t adc_values[2];  // last ADC measurements (0=voltage, 1=temperature)
+uint8_t adcint_enable = 0;  // is the current ADC result needed?
+void ADC_inner();  // do the actual ADC-related calculations
+
+static inline void ADC_voltage_handler();
 volatile uint8_t voltage = 0;
-volatile uint8_t adcint_enable;  // kludge, because adc auto-retrigger won't turn off
 void low_voltage();
+
 #ifdef USE_BATTCHECK
 void battcheck();
 #ifdef BATTCHECK_VpT
@@ -50,7 +59,7 @@ void battcheck();
 #define USE_BLINK_DIGIT
 #endif
 #endif
-#endif
+#endif  // ifdef USE_LVP
 
 
 #ifdef USE_THERMAL_REGULATION
@@ -79,7 +88,8 @@ int8_t therm_cal_offset = 0;
 //void low_temperature();
 //void high_temperature();
 volatile uint8_t reset_thermal_history = 1;
-#endif
+static inline void ADC_temperature_handler();
+#endif  // ifdef USE_THERMAL_REGULATION
 
 
 inline void ADC_on();
diff --git a/spaghetti-monster/fsm-events.c b/spaghetti-monster/fsm-events.c
index 3e9a12d..a1b013a 100644
--- a/spaghetti-monster/fsm-events.c
+++ b/spaghetti-monster/fsm-events.c
@@ -110,7 +110,7 @@ uint8_t nice_delay_ms(uint16_t ms) {
     /*  // delay_zero() implementation
     if (ms == 0) {
         CLKPR = 1<<CLKPCE; CLKPR = 0;  // full speed
-        _delay_loop_2(BOGOMIPS*98/100/3);
+        _delay_loop_2(BOGOMIPS*95/100/3);
         return 1;
     }
     */
@@ -120,15 +120,15 @@ uint8_t nice_delay_ms(uint16_t ms) {
         uint8_t level = actual_level;  // volatile, avoid repeat access
         if (level < QUARTERSPEED_LEVEL) {
             clock_prescale_set(clock_div_4);
-            _delay_loop_2(BOGOMIPS*98/100/4);
+            _delay_loop_2(BOGOMIPS*95/100/4);
         }
         //else if (level < HALFSPEED_LEVEL) {
         //    clock_prescale_set(clock_div_2);
-        //    _delay_loop_2(BOGOMIPS*98/100/2);
+        //    _delay_loop_2(BOGOMIPS*95/100/2);
         //}
         else {
             clock_prescale_set(clock_div_1);
-            _delay_loop_2(BOGOMIPS*98/100);
+            _delay_loop_2(BOGOMIPS*95/100);
         }
         // restore regular clock speed
         clock_prescale_set(clock_div_1);
@@ -136,15 +136,18 @@ uint8_t nice_delay_ms(uint16_t ms) {
         // underclock MCU to save power
         clock_prescale_set(clock_div_4);
         // wait
-        _delay_loop_2(BOGOMIPS*98/100/4);
+        _delay_loop_2(BOGOMIPS*95/100/4);
         // restore regular clock speed
         clock_prescale_set(clock_div_1);
         #endif  // ifdef USE_RAMPING
         #else
         // wait
-        _delay_loop_2(BOGOMIPS*98/100);
+        _delay_loop_2(BOGOMIPS*95/100);
         #endif  // ifdef USE_DYNAMIC_UNDERCLOCKING
 
+        // run pending system processes while we wait
+        handle_deferred_interrupts();
+
         if ((nice_delay_interrupt) || (old_state != current_state)) {
             return 0;  // state changed; abort
         }
diff --git a/spaghetti-monster/fsm-main.c b/spaghetti-monster/fsm-main.c
index e537a9e..c9ab69b 100644
--- a/spaghetti-monster/fsm-main.c
+++ b/spaghetti-monster/fsm-main.c
@@ -123,7 +123,6 @@ int main() {
     #else
     delay_4ms(1);
     #endif
-    empty_event_sequence();
 
     // fallback for handling a few things
     #ifndef DONT_USE_DEFAULT_STATE
@@ -160,6 +159,9 @@ int main() {
             standby_mode();
         }
 
+        // catch up on interrupts
+        handle_deferred_interrupts();
+
         // give the recipe some time slices
         loop();
 
@@ -168,4 +170,22 @@ int main() {
     }
 }
 
+
+void handle_deferred_interrupts() {
+    /*
+    if (irq_pcint) {  // button pressed or released
+        // nothing to do here
+        // (PCINT only matters during standby)
+    }
+    */
+    if (irq_adc) {  // ADC done measuring
+        ADC_inner();
+        // irq_adc = 0;  // takes care of itself
+    }
+    if (irq_wdt) {  // the clock ticked
+        WDT_inner();
+        // irq_wdt = 0;  // takes care of itself
+    }
+}
+
 #endif
diff --git a/spaghetti-monster/fsm-main.h b/spaghetti-monster/fsm-main.h
index cc469d7..55ae2ff 100644
--- a/spaghetti-monster/fsm-main.h
+++ b/spaghetti-monster/fsm-main.h
@@ -21,5 +21,7 @@
 #define FSM_MAIN_H
 
 int main();
+// needs to run frequently to execute the logic for WDT and ADC and stuff
+void handle_deferred_interrupts();
 
 #endif
diff --git a/spaghetti-monster/fsm-pcint.c b/spaghetti-monster/fsm-pcint.c
index 4928980..a4a496a 100644
--- a/spaghetti-monster/fsm-pcint.c
+++ b/spaghetti-monster/fsm-pcint.c
@@ -24,19 +24,9 @@
 #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) | ((SWITCH_PORT & (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;
+    uint8_t value = ((SWITCH_PORT & (1<<SWITCH_PIN)) == 0);
+    button_last_state = value;
+    return value;
 }
 
 inline void PCINT_on() {
@@ -75,7 +65,10 @@ inline void PCINT_off() {
 
 //void button_change_interrupt() {
 #if (ATTINY == 25) || (ATTINY == 45) || (ATTINY == 85) || (ATTINY == 1634)
-EMPTY_INTERRUPT(PCINT0_vect);
+//EMPTY_INTERRUPT(PCINT0_vect);
+ISR(PCINT0_vect) {
+    irq_pcint = 1;
+}
 #else
     #error Unrecognized MCU type
 #endif
diff --git a/spaghetti-monster/fsm-pcint.h b/spaghetti-monster/fsm-pcint.h
index ec3ae4b..a7f3733 100644
--- a/spaghetti-monster/fsm-pcint.h
+++ b/spaghetti-monster/fsm-pcint.h
@@ -20,6 +20,7 @@
 #ifndef FSM_PCINT_H
 #define FSM_PCINT_H
 
+volatile uint8_t irq_pcint = 0;  // pin change interrupt happened?
 //static volatile uint8_t button_was_pressed;
 #define BP_SAMPLES 32
 volatile uint8_t button_last_state;
diff --git a/spaghetti-monster/fsm-standby.c b/spaghetti-monster/fsm-standby.c
index 44b047a..4124d92 100644
--- a/spaghetti-monster/fsm-standby.c
+++ b/spaghetti-monster/fsm-standby.c
@@ -42,13 +42,15 @@ void sleep_until_eswitch_pressed()
     // make sure switch isn't currently pressed
     while (button_is_pressed()) {}
     empty_event_sequence();  // cancel pending input on suspend
-    //PCINT_since_WDT = 0;  // ensure PCINT won't ignore itself
 
     PCINT_on();  // wake on e-switch event
 
     #ifdef TICK_DURING_STANDBY
+    // detect which type of event caused a wake-up
+    irq_adc = 0;
+    irq_wdt = 0;
+    irq_pcint = 0;
     while (go_to_standby) {
-        f_wdt = 0;  // detect if WDT was what caused a wake-up
     #else
         go_to_standby = 0;
     #endif
@@ -65,10 +67,19 @@ void sleep_until_eswitch_pressed()
         sleep_disable();
 
     #ifdef TICK_DURING_STANDBY
-        // determine what woke us up... WDT or PCINT
-        if (! f_wdt) {  // PCINT went off; wake up
+        // determine what woke us up...
+        if (irq_pcint) {  // button pressed; wake up
             go_to_standby = 0;
         }
+        if (irq_adc) {  // ADC done measuring
+            adcint_enable = 1;
+            ADC_inner();
+            //ADC_off();  // takes care of itself
+            //irq_adc = 0;  // takes care of itself
+        }
+        if (irq_wdt) {  // generate a sleep tick
+            WDT_inner();
+        }
     }
     #endif
 
diff --git a/spaghetti-monster/fsm-wdt.c b/spaghetti-monster/fsm-wdt.c
index 6e61e87..beab1a2 100644
--- a/spaghetti-monster/fsm-wdt.c
+++ b/spaghetti-monster/fsm-wdt.c
@@ -82,11 +82,23 @@ inline void WDT_off()
 
 // clock tick -- this runs every 16ms (62.5 fps)
 ISR(WDT_vect) {
+    irq_wdt = 1;  // WDT event happened
+}
+
+void WDT_inner() {
+    irq_wdt = 0;  // WDT event handled; reset flag
+
     static uint8_t adc_trigger = 0;
 
-    #ifdef TICK_DURING_STANDBY
-    f_wdt = 1;  // WDT event happened
+    // detect and emit button change events (even during standby)
+    uint8_t was_pressed = button_last_state;
+    uint8_t pressed = button_is_pressed();
+    if (was_pressed != pressed) {
+        go_to_standby = 0;
+        PCINT_inner(pressed);
+    }
 
+    #ifdef TICK_DURING_STANDBY
     static uint16_t sleep_counter = 0;
     // handle standby mode specially
     if (go_to_standby) {
@@ -107,11 +119,6 @@ ISR(WDT_vect) {
     else { sleep_counter = 0; }
     #endif
 
-    // detect and emit button change events
-    uint8_t was_pressed = button_last_state;
-    uint8_t pressed = button_is_pressed();
-    if (was_pressed != pressed) PCINT_inner(pressed);
-
     // cache this here to reduce ROM size, because it's volatile
     uint16_t ticks_since_last = ticks_since_last_event;
  
@@ -178,6 +185,7 @@ ISR(WDT_vect) {
         if (go_to_standby) ADC_on();
         #endif
         ADC_start_measurement();
+        irq_adc_stable = 0;
         adcint_enable = 1;
     }
     #endif
diff --git a/spaghetti-monster/fsm-wdt.h b/spaghetti-monster/fsm-wdt.h
index 78fe791..d127551 100644
--- a/spaghetti-monster/fsm-wdt.h
+++ b/spaghetti-monster/fsm-wdt.h
@@ -25,9 +25,9 @@
 void WDT_on();
 inline void WDT_off();
 
-#ifdef TICK_DURING_STANDBY
-volatile uint8_t f_wdt = 0;
+volatile uint8_t irq_wdt = 0;  // WDT interrupt happened?
 
+#ifdef TICK_DURING_STANDBY
   #if defined(USE_INDICATOR_LED) || defined(USE_AUX_RGB_LEDS)
   // measure battery charge while asleep
   #define USE_SLEEP_LVP