improved calibration

fablab-ka · Nov 28, 2020 · e7e5b3a · e7e5b3a
1 parent 8de0ba8
commit e7e5b3a
Show file tree

Hide file tree

Showing 3 changed files with 63 additions and 15 deletions.
diff --git a/Software/co2ampel/co2ampel.ino b/Software/co2ampel/co2ampel.ino
@@ -69,19 +69,22 @@ void selftest()
   delay(5000);
   bool ok=true;
   sensors_event_t pressure_event;
-  uint16_t co2;
+  uint16_t co2=0;
 
   if((!bmpReady&&BMP_ENABLED) || !scd30Ready) ok=false;
   else {
-    while (!digitalRead(GPIO_SCD30_RDY) || ! airSensor.dataAvailable()) {
-      delay(500);
+    uint8_t i=0;
+    while (co2<SCD30_MIN_PPM && i++<10) { 
+      while (!digitalRead(GPIO_SCD30_RDY) || ! airSensor.dataAvailable()) {
+        delay(500);
+      }
+      co2 = airSensor.getCO2();
     }
-    co2 = airSensor.getCO2();
-    if (co2 < 300) {
+    if (co2 < SCD30_MIN_PPM) {
       Serial.print("co2 too low: ");
-      Serial.println(co2);
       ok=false;
-    }  
+    } else Serial.print("co2 ok: ");
+    Serial.println(co2);
     if (bmpReady) {
       bmp_pressure->getEvent(&pressure_event);  
       if (pressure_event.pressure < 700) {
@@ -101,7 +104,7 @@ void selftest()
     if(beepEnabled) beepFailure(configManager);
     if(!bmpReady) ledBlink(BLUE,RED,5000);
     else if(pressure_event.pressure < 700) ledBlink(BLUE,DARK,5000);
-    else if (co2 < 350) ledBlink(YELLOW,DARK,5000);
+    else if (co2 < SCD30_MIN_PPM) ledBlink(YELLOW,DARK,5000);
   }
 }
 
@@ -127,9 +130,52 @@ void setConfig(String& jsonString) {
 void startCalibration() {
   ledSetColor(YELLOW2);
   delay(600000); // wait 10min
-  bool ok = airSensor.setForcedRecalibrationFactor(410);
-  Serial.print("calibration status: ");
-  Serial.println(ok);
+  bool ok = false;
+  uint8_t calCount=0;
+  while (!ok && calCount<5) {
+    ok = airSensor.setForcedRecalibrationFactor(SCD30_CALIBRATION_PPM);
+    Serial.print("calibration status from sensor: ");
+    Serial.println(ok);
+    ledSetColor(BLUE);
+    uint8_t okcount=0;
+    uint16_t co2=0;
+    uint16_t co2last=0;
+    while (okcount<10) {  
+      while (!digitalRead(GPIO_SCD30_RDY) || ! airSensor.dataAvailable()) {
+        delay(500);
+      }
+      co2 = airSensor.getCO2();
+      uint16_t delta=abs(co2last-co2);
+      Serial.print("co2: ");
+      Serial.print(co2);
+      Serial.print(" delta: ");
+      Serial.println(delta);
+      if(delta<=10) okcount++;
+      else okcount=0;
+      co2last=co2;
+    }
+    ledSetColor(YELLOW2);
+    delay(60000);
+
+    // check the next 20 values whether they are within the specification: +-(30ppm+3%MV)
+    uint16_t co2min=SCD30_CALIBRATION_PPM-(30+0.03*SCD30_CALIBRATION_PPM);
+    uint16_t co2max=SCD30_CALIBRATION_PPM+(30+0.03*SCD30_CALIBRATION_PPM);
+    for (uint8_t i=0; i < 20; i++) {
+      while (!digitalRead(GPIO_SCD30_RDY) || ! airSensor.dataAvailable()) {
+        delay(500);
+      }
+      co2 = airSensor.getCO2();
+      if(co2<co2min || co2>co2max) {
+        Serial.print("measured value outside specification: ");
+        Serial.println(co2);
+        ok=false;
+        break;
+      } else {
+        Serial.print("measured value ok: ");
+        Serial.println(co2);
+      }
+    }
+  }
   if (ok) {
     ledBlink(GREEN,DARK,2000);
     ledSetColor(GREEN2);
@@ -245,7 +291,7 @@ void loop()
 
 #ifdef GPIO_SWITCH
   // check recalibration switch
-  if(millis() < 30000 && abs(millis()-lastSwitchChange) > 500) {
+  if(millis() < 60000 && abs(millis()-lastSwitchChange) > 500) {
     int switchState = digitalRead(GPIO_SWITCH);
     if(switchState==1 && recalibrateSwitch==0) {
       recalibrateSwitch++;

diff --git a/Software/co2ampel/config.h b/Software/co2ampel/config.h
@@ -10,7 +10,7 @@
 #define CONFIG_H
 
 /******************************* Version **************************************/
-#define VERSION 2
+#define VERSION 3
 
 /******************************* MQTT **************************************/
 
@@ -37,6 +37,8 @@ enum Color {GREEN, YELLOW, RED, BLUE, DARK, WHITE, GREEN2, YELLOW2, RED2};
 #define SCD30_AUTOCALIBRATION 0
 #define SCD30_CALIBRATION_MIN_RUNTIME 180 //seconds
 #define SCD30_MEASUREMENT_INTERVAL 2 // seconds (recalibrate, if you change this value)
+#define SCD30_MIN_PPM 350
+#define SCD30_CALIBRATION_PPM 410
 
 /******************************* thresholds **************************************/
 #define TH_GREEN 800 //overriden by th_green from config.json

diff --git a/Software/co2ampel/led.cpp b/Software/co2ampel/led.cpp
@@ -71,8 +71,8 @@ void ledSetColor(Color color) {
       fill_solid(led2,NUMPIXELS2,CRGB::Black); 
       break;
     case BLUE:
-      fill_solid(led1,NUMPIXELS1,CRGB::Blue);
-      fill_solid(led2,NUMPIXELS2,CRGB::Red);
+      fill_solid(led1,NUMPIXELS1,CRGB::Black);
+      fill_solid(led2,NUMPIXELS2,CRGB::Blue);
       break;
     case WHITE: 
       fill_solid(led1,NUMPIXELS1,CRGB::White);