Jens Schmidt / MicrobitIAQ

uses BBC micro:bit to measure and display indoor air quality using Bosch BME680 and/or Sensirion SGP30

Dependencies:   microbit

uses Bosch BME680 and/or Sensirion SGP30 sensors to measure indor air quality

sensors should be connected to BBC micro:bit using i2c

commands are received and data is being sent using uBit / nordic radio protocol

display ---

last line always indicates: - first dot: bme680 detected - second dot: sgp30 detected - third dot: sgp 30 setting humidity/temperature - fourth dor: sgp30 measuring - fith dot: bme680 measuring

the detect dots should be in a stable state (not blinking) the measuring dots should be blinking (constant light means: measurement failed)

if only one bme680 is present: - first 3 lines indicate gas resistence (air quality / more dots == worse quality) - fourth line indicates humidity level

if only sgp30 is present: - first two lines indicate SGP30 VOC level - third and fourth line indicate sgp30 CO2 level

if both sensors are present: - first line indicates SGP30 VOC level - second line line indicates sgp30 CO2 level - third line indicates bme680 gas resistence (air quality) - fourth line indicates bme 680 humidity level

buttons - B display state, switches betweeen - full bright - low light - display off

AB reset sgp30 baseline in non volatile storage

data logging -- during measurements the minimum and mximum values for each measured value (temperature, air pressure, humidity,gas resistance, VOC, CO2) are being stored in non volatile storage those (and the last measurement results) are being shown when btn A has been pressed

Physics/physics.cpp@60:6b21ca38ee7c, 2022-06-03 (annotated)

Committer:
jsa1969
Date:
Fri Jun 03 17:05:56 2022 +0000
Revision:
60:6b21ca38ee7c
Parent:
15:8bb5c580d453 
cleanup

Who changed what in which revision?

UserRevisionLine numberNew contents of line
jsa1969 1:f9245fb53737 1 #include "physics.h"
jsa1969 1:f9245fb53737 2
jsa1969 15:8bb5c580d453 3 int Physics::absHumidity(const int relHumidity, const int temperature){
jsa1969 1:f9245fb53737 4 const float tmpFloat = (float)temperature;
jsa1969 2:544117df8c65 5 return (int)((relHumidity * saettigung(tmpFloat))/1000000);
jsa1969 1:f9245fb53737 6 }
jsa1969 1:f9245fb53737 7
jsa1969 15:8bb5c580d453 8 float Physics::saettigung(const float tmpFloat) {
jsa1969 1:f9245fb53737 9 float dd = saettigungsdampfdruck(tmpFloat);
jsa1969 1:f9245fb53737 10 return dd/(4.6152*(273.15+tmpFloat));
jsa1969 1:f9245fb53737 11 }
jsa1969 1:f9245fb53737 12
jsa1969 15:8bb5c580d453 13 float Physics::saettigungsdampfdruck(const float tmpFloat){
jsa1969 1:f9245fb53737 14 const float t1 = 16.62 * tmpFloat;
jsa1969 1:f9245fb53737 15 const float t2 = 243.12 + tmpFloat;
jsa1969 1:f9245fb53737 16 const float factor1 = expf(t1 / t2);
jsa1969 2:544117df8c65 17 return 6112 * factor1;
jsa1969 1:f9245fb53737 18 }