Added thermal regulation to SpaghettiMonster / Baton.

Made some LVP values configurable.
Removed high_temperature() / low_temperature() shortcuts for now.

1 files changed, 132 insertions, 4 deletions

diff --git a/spaghetti-monster/fsm-adc.c b/spaghetti-monster/fsm-adc.c
index 11468b9..8af3487 100644
--- a/spaghetti-monster/fsm-adc.c
+++ b/spaghetti-monster/fsm-adc.c
@@ -35,9 +35,18 @@ inline void ADC_off() {
     ADCSRA &= ~(1<<ADEN); //ADC off
 }
 
+// Each full cycle runs 7.8X per second with just voltage enabled,
+// or 3.9X per second with voltage and temperature.
+#if defined(USE_LVP) && defined(USE_THERMAL_REGULATION)
+#define ADC_CYCLES_PER_SECOND 4
+#else
+#define ADC_CYCLES_PER_SECOND 8
+#endif
 // TODO: is this better done in main() or WDT()?
 ISR(ADC_vect) {
     static uint8_t adc_step = 0;
+
+    // LVP declarations
     #ifdef USE_LVP
     #ifdef USE_LVP_AVG
     #define NUM_VOLTAGE_VALUES 4
@@ -45,14 +54,24 @@ ISR(ADC_vect) {
     #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
+    #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
     #endif
 
+    // thermal declarations
     #ifdef USE_THERMAL_REGULATION
     #define NUM_THERMAL_VALUES 4
+    #define NUM_THERMAL_VALUES_HISTORY 16
     #define ADC_STEPS 4
-    static int16_t temperature_values[NUM_THERMAL_VALUES];
+    static uint8_t first_temp_reading = 1;
+    static int16_t temperature_values[NUM_THERMAL_VALUES];  // last few readings in C
+    static int16_t temperature_history[NUM_THERMAL_VALUES_HISTORY];  // 13.2 fixed-point
+    static uint8_t temperature_timer = 0;
+    static uint8_t overheat_lowpass = 0;
+    static uint8_t underheat_lowpass = 0;
+    #define TEMPERATURE_TIMER_START (THERMAL_WARNING_SECONDS*ADC_CYCLES_PER_SECOND)  // N seconds between thermal regulation events
+    #define OVERHEAT_LOWPASS_STRENGTH ADC_CYCLES_PER_SECOND  // lowpass for one second
+    #define UNDERHEAT_LOWPASS_STRENGTH ADC_CYCLES_PER_SECOND  // lowpass for one second
     #else
     #define ADC_STEPS 2
     #endif
@@ -116,7 +135,116 @@ ISR(ADC_vect) {
     }
     #endif  // ifdef USE_LVP
 
-    // TODO: 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;
+
+        // prime on first execution
+        if (first_temp_reading) {
+            first_temp_reading = 0;
+            for(uint8_t i=0; i<NUM_THERMAL_VALUES; i++)
+                temperature_values[i] = temp;
+            for(uint8_t i=0; i<NUM_THERMAL_VALUES_HISTORY; i++)
+                temperature_history[i] = temp;
+            temperature = temp;
+        } else {  // update our current temperature estimate
+            uint8_t i;
+            int16_t total=0;
+
+            // rotate array
+            for(i=0; i<NUM_THERMAL_VALUES-1; i++) {
+                temperature_values[i] = temperature_values[i+1];
+                total += temperature_values[i];
+            }
+            temperature_values[i] = temp;
+            total += temp;
+
+            // Divide back to original range:
+            //temperature = total >> 2;
+            // More precise method: use noise as extra precision
+            // (values are now basically fixed-point, signed 13.2)
+            temperature = total;
+        }
+
+        // guess what the temperature will be in a few seconds
+        {
+            uint8_t i;
+            int16_t diff;
+
+            // algorithm tweaking; not really intended to be modified
+            // how far ahead should we predict?
+            #define THERM_PREDICTION_STRENGTH 4
+            // how proportional should the adjustments be?
+            #define THERM_DIFF_ATTENUATION 4
+            // acceptable temperature window size in C
+            #define THERM_WINDOW_SIZE 8
+            // highest temperature allowed
+            // (convert configured value to 13.2 fixed-point)
+            #define THERM_CEIL (therm_ceil<<2)
+            // bottom of target temperature window (13.2 fixed-point)
+            #define THERM_FLOOR (THERM_CEIL - (THERM_WINDOW_SIZE<<2))
+
+            // rotate measurements and add a new one
+            for (i=0; i<NUM_THERMAL_VALUES_HISTORY-1; i++) {
+                temperature_history[i] = temperature_history[i+1];
+            }
+            temperature_history[NUM_THERMAL_VALUES_HISTORY-1] = temperature;
+
+            // guess what the temp will be several seconds in the future
+            diff = temperature_history[NUM_THERMAL_VALUES_HISTORY-1] - temperature_history[0];
+            projected_temperature = temperature_history[NUM_THERMAL_VALUES_HISTORY-1] + (diff<<THERM_PREDICTION_STRENGTH);
+
+        }
+
+        // cancel counters if necessary
+        if (projected_temperature > THERM_FLOOR) {
+            underheat_lowpass = 0;  // we're definitely not too cold
+        } else if (projected_temperature < THERM_CEIL) {
+            overheat_lowpass = 0;  // we're definitely not too hot
+        }
+
+        if (temperature_timer) {
+            temperature_timer --;
+        } else {  // it has been long enough since the last warning
+
+            // Too hot?
+            if (projected_temperature > THERM_CEIL) {
+                if (overheat_lowpass < OVERHEAT_LOWPASS_STRENGTH) {
+                    overheat_lowpass ++;
+                } else {
+                    // how far above the ceiling?
+                    int16_t howmuch = (projected_temperature - THERM_CEIL) >> THERM_DIFF_ATTENUATION;
+                    if (howmuch < 1) howmuch = 1;
+                    // try to send out a warning
+                    emit(EV_temperature_high, howmuch);
+                    // reset counters
+                    temperature_timer = TEMPERATURE_TIMER_START;
+                    overheat_lowpass = 0;
+                }
+            }
+
+            // Too cold?
+            else if (projected_temperature < THERM_FLOOR) {
+                if (underheat_lowpass < UNDERHEAT_LOWPASS_STRENGTH) {
+                    underheat_lowpass ++;
+                } else {
+                    // how far below the floor?
+                    int16_t howmuch = (THERM_FLOOR - projected_temperature) >> THERM_DIFF_ATTENUATION;
+                    if (howmuch < 1) howmuch = 1;
+                    // try to send out a warning
+                    emit(EV_temperature_low, howmuch);
+                    // reset counters
+                    temperature_timer = TEMPERATURE_TIMER_START;
+                    underheat_lowpass = 0;
+                }
+            }
+        }
+    }
+    #endif  // ifdef USE_THERMAL_REGULATION
+
 
     // start another measurement for next time
     #ifdef USE_THERMAL_REGULATION