pyupm_mg811 module¶
-
class
pyupm_mg811.MG811(pin, dpin, aref=5.0)[source]¶ Bases:
objectAPI for the DFRobot CO2 Sensor.
ID: mg811
Name: CO2 Sensor
Other Names: MG811
Category: gaseous
Manufacturer: dfrobot
Link:http://www.dfrobot.com/index.php?route=product/product&product_id=1023
Connection: analog This sensor returns an an analog voltage that falls as the concentration of CO2 increases. It contains a heater that must be allowed to ‘warm’ up the sensor before measurements are stable (hours to days is the recommendation). It requires that the MCU be powered from an external power supply (not USB) at 5v, since the heater will consume significant current.
The sensor should be allowed to ‘heat’ up for some time before beginning use, typically a couple of hours minimum. It also needs fairly precise calibration at 400ppm and 1000ppm to return meaningful results.
The sensor also incorporates a potentiometer that can be adjusted to specific threshold. Once that threshold is reached, an LED on the sensor will light, and the digital pin will be driven high.
C++ includes: mg811.hpp
-
getReferenceVoltage()[source]¶ float getReferenceVoltage()
Return a cumputed reference voltage to be used in calibration. Computed reference voltage
-
ppm()[source]¶ float ppm()
Returns the computed CO2 concentration in ppm (Parts Per Million). This method will return 0.0 if the reference voltage is greater than the ppm400 value. Essentially, ppm values below 400 will be reported as 0.
The computed CO2 concentration in ppm
-
setCalibration(ppm400, ppm1000)[source]¶ void setCalibration(float ppm400, float ppm1000)
Set calibration parameters. You should measure the reference voltage you get when at CO2 concentrations of 400ppm (ambient) and 1000ppm using the getReferenceVoltage() method. Then specify those voltages here for more accurate results.
ppm400: The measured reference voltage at 400 ppm
ppm1000: The measured reference voltage at 1000 ppm
-