co2_sensor: Reset SCD30 after startup

Sometimes after a hard reset of the ESP the SCD30
needs a long time until returning the first measurement.
Resetting it after startup seems to fix this behaviour.

ampel-firmware/co2_sensor.cpp

@@ -83,6 +83,10 @@ namespace sensor {
       ESP.restart();
     }
 
+    // Sometimes after a hard reset of the ESP the SCD30 needs
+    // a long time until returning the first measurement. Resetting it
+    // after startup seems to fix this behaviour.
+    scd30.reset();
     switchState(BOOTUP);
 
     Serial.print(F("Setting temperature offset to -"));

[Eric Duminil]

Interesting. Is the behaviour documented somewhere? I think that the old measurement interval is kept after a restart. So if it was 60s, it might take almost a minute before the interval is set to 2s.

I also would like to know if it has any influence on the auto-calibration feature, which should run for 7 days without interruption.

Once again, the scd30 is a black box, and I don't understand its behaviour. :-/

[Käppler]

I don't really know. I must admit that I did not read the SCD30 documentation yet, apart from the datasheet. Your explanation (that the old measurement interval is kept until the next measurement) makes sense. Regarding auto-calibration, if you reset the ESP that would not count as "running without interruption" either, even without explicitly resetting the SCD30, too?