Merge branch 'refactor/fixstartup' into develop

ampel-firmware/co2_sensor.cpp

@@ -3,10 +3,12 @@
 namespace config {
   // Values should be defined in config.h
   uint16_t measurement_timestep = MEASUREMENT_TIMESTEP; // [s] Value between 2 and 1800 (range for SCD30 sensor)
+  const uint16_t measurement_timestep_bootup = 2; // [s] Measurement timestep during acclimatization
   const uint16_t altitude_above_sea_level = ALTITUDE_ABOVE_SEA_LEVEL; // [m]
   uint16_t co2_calibration_level = ATMOSPHERIC_CO2_CONCENTRATION; // [ppm]
   int8_t max_deviation_during_calibration = 30; // [ppm]
   int8_t enough_stable_measurements = 60;
+  const uint8_t max_deviation_during_bootup = 20; // [%]
 #ifdef TEMPERATURE_OFFSET
   // Residual heat from CO2 sensor seems to be high enough to change the temperature reading. How much should it be offset?
   // NOTE: Sign isn't relevant. The returned temperature will always be shifted down.
@@ -28,31 +30,27 @@ namespace sensor {
 
   /**
    * Define sensor states
-   * INITIAL -> initial state
-   * BOOTUP -> state after initializing the sensor, i.e. after scd.begin()
+   * BOOTUP -> initial state, until first >0 ppm values are returned
    * READY -> sensor does output valid information (> 0 ppm) and no other condition takes place
    * NEEDS_CALIBRATION -> sensor measurements are too low (< 250 ppm)
-   * PREPARE_CALIBRATION -> forced calibration was initiated, waiting for stable measurements
-   * CALIBRATION -> the sensor does calibrate itself
+   * PREPARE_CALIBRATION_UNSTABLE -> forced calibration was initiated, last measurements were too far apart
+   * PREPARE_CALIBRATION_STABLE -> forced calibration was initiated, last measurements were close to each others
    */
   enum state {
-    INITIAL,
     BOOTUP,
     READY,
     NEEDS_CALIBRATION,
     PREPARE_CALIBRATION_UNSTABLE,
-    PREPARE_CALIBRATION_STABLE,
-    CALIBRATION
+    PREPARE_CALIBRATION_STABLE
   };
   const char *state_names[] = {
-      "INITIAL",
       "BOOTUP",
       "READY",
       "NEEDS_CALIBRATION",
       "PREPARE_CALIBRATION_UNSTABLE",
-      "PREPARE_CALIBRATION_STABLE",
-      "CALIBRATION" };
-  state current_state = INITIAL;
+      "PREPARE_CALIBRATION_STABLE" };
+
+  state current_state = BOOTUP;
   void switchState(state);
 
   void initialize() {
@@ -78,28 +76,33 @@ namespace sensor {
       ESP.restart();
     }
 
-    switchState(BOOTUP);
-
-    // SCD30 has its own timer.
-    //NOTE: The timer seems to be inaccurate, though, possibly depending on voltage. Should it be offset?
-    Serial.print(F("Setting SCD30 timestep to "));
-    Serial.print(config::measurement_timestep);
-    Serial.println(" s.");
-    scd30.setMeasurementInterval(config::measurement_timestep); // [s]
+    // Changes of the SCD30's measurement timestep do not come into effect
+    // before the next measurement takes place. That means that after a hard reset
+    // of the ESP the SCD30 sometimes needs a long time until switching back to 2 s
+    // for acclimatization. Resetting it after startup seems to fix this behaviour.
+    scd30.reset();
 
     Serial.print(F("Setting temperature offset to -"));
     Serial.print(abs(config::temperature_offset));
-    Serial.println(" K.");
+    Serial.println(F(" K."));
     scd30.setTemperatureOffset(abs(config::temperature_offset)); // setTemperatureOffset only accepts positive numbers, but shifts the temperature down.
     delay(100);
 
     Serial.print(F("Temperature offset is : -"));
     Serial.print(scd30.getTemperatureOffset());
-    Serial.println(" K");
+    Serial.println(F(" K"));
 
     Serial.print(F("Auto-calibration is "));
     Serial.println(config::auto_calibrate_sensor ? "ON." : "OFF.");
 
+    // SCD30 has its own timer.
+    //NOTE: The timer seems to be inaccurate, though, possibly depending on voltage. Should it be offset?
+    Serial.println();
+    Serial.print(F("Setting SCD30 timestep to "));
+    Serial.print(config::measurement_timestep_bootup);
+    Serial.println(F(" s during acclimatization."));
+    scd30.setMeasurementInterval(config::measurement_timestep_bootup); // [s]
+
     sensor_console::defineIntCommand("co2", setCO2forDebugging, F(" 1500 (Sets co2 level, for debugging purposes)"));
     sensor_console::defineIntCommand("timer", setTimer, F(" 30 (Sets measurement interval, in s)"));
     sensor_console::defineCommand("calibrate", startCalibrationProcess, F(" (Starts calibration process)"));
@@ -117,10 +120,20 @@ namespace sensor {
     int32_t now = millis();
     Serial.print(F("Measurement time offset : "));
     Serial.print(now - previous_measurement_at - config::measurement_timestep * 1000);
-    Serial.println(" ms.");
+    Serial.println(F(" ms."));
     previous_measurement_at = now;
   }
 
+  bool hasSensorSettled() {
+    static uint16_t last_co2 = 0;
+    uint16_t delta;
+    delta = abs(co2 - last_co2);
+    last_co2 = co2;
+    // We assume the sensor has acclimated to the environment if measurements
+    // change less than a specified percentage of the current value.
+    return (co2 > 0 && delta < ((uint32_t) co2 * config::max_deviation_during_bootup / 100));
+  }
+
   bool countStableMeasurements() {
     // Returns true, if a sufficient number of stable measurements has been observed.
     static int16_t previous_co2 = 0;
@@ -151,7 +164,6 @@ namespace sensor {
   }
 
   void calibrateAndRestart() {
-    switchState(CALIBRATION);
     Serial.print(F("Calibrating SCD30 now..."));
     scd30.setAltitudeCompensation(config::altitude_above_sea_level);
     scd30.setForcedRecalibrationFactor(config::co2_calibration_level);
@@ -177,19 +189,25 @@ namespace sensor {
     if (config::debug_sensor_states) {
       Serial.print(F("Changing sensor state: "));
       Serial.print(state_names[current_state]);
-      Serial.print(" -> ");
+      Serial.print(F(" -> "));
       Serial.println(state_names[new_state]);
     }
     current_state = new_state;
   }
 
   void switchStateForCurrentPPM() {
-    if (co2 == 0) {
-      // NOTE: Data is available, but it's sometimes erroneous: the sensor outputs
-      // zero ppm but non-zero temperature and non-zero humidity.
-      Serial.println(F("Invalid sensor data - CO2 concentration supposedly 0 ppm"));
-      switchState(BOOTUP);
-    } else if ((current_state == PREPARE_CALIBRATION_UNSTABLE) || (current_state == PREPARE_CALIBRATION_STABLE)) {
+    if (current_state == BOOTUP) {
+      if (!hasSensorSettled()) {
+        return;
+      }
+      switchState(READY);
+      Serial.println(F("Sensor acclimatization finished."));
+      Serial.print(F("Setting SCD30 timestep to "));
+      Serial.print(config::measurement_timestep);
+      Serial.println(F(" s."));
+      scd30.setMeasurementInterval(config::measurement_timestep); // [s]
+    }
+    if ((current_state == PREPARE_CALIBRATION_UNSTABLE) || (current_state == PREPARE_CALIBRATION_STABLE)) {
       // Check for pre-calibration states first, because we do not want to
       // leave them before calibration is done.
       bool ready_for_calibration = countStableMeasurements();
@@ -236,8 +254,6 @@ namespace sensor {
     case PREPARE_CALIBRATION_STABLE:
       led_effects::showWaitingLED(color::green);
       break;
-    case CALIBRATION: // Nothing to do, will restart soon.
-      break;
     default:
       Serial.println(F("Encountered unknown sensor state")); // This should not happen.
     }
@@ -264,7 +280,9 @@ namespace sensor {
 
     showState();
 
-    return freshData;
+    // Report data for further processing only if the data is reliable
+    // (state 'READY') or manual calibration is necessary (state 'NEEDS_CALIBRATION').
+    return freshData && (current_state == READY || current_state == NEEDS_CALIBRATION);
   }
 
   /*****************************************************************
@@ -288,7 +306,7 @@ namespace sensor {
     if (timestep >= 2 && timestep <= 1800) {
       Serial.print(F("Setting Measurement Interval to : "));
       Serial.print(timestep);
-      Serial.println("s.");
+      Serial.println(F("s."));
       sensor::scd30.setMeasurementInterval(timestep);
       config::measurement_timestep = timestep;
       led_effects::showKITTWheel(color::green, 1);
@@ -300,7 +318,7 @@ namespace sensor {
       Serial.print(F("Force calibration, at "));
       config::co2_calibration_level = calibrationLevel;
       Serial.print(config::co2_calibration_level);
-      Serial.println(" ppm.");
+      Serial.println(F(" ppm."));
       sensor::startCalibrationProcess();
     }
   }