MQ135 sensor Attribute Error
Posted: Sat Apr 02, 2022 2:51 am
I'm trying to connect a mq135 gas/c02 sensor to my project and found the drivers link in Awsome MicroPython to GitHub HERE and I just cant get this thing to work. I'm using the DHT22 temp and hum sensor (I know it works) instead of the DHT11 so I had to change a few things for that. Anyways I'm getting the error:
DRIVER:
and I have no idea why? line 12 in the example is rzero = MQ135.get_rzero(adc3) and below I posted the example and driver. Sugestions?Traceback (most recent call last):
File "<stdin>", line 12, in <module>
File "mq135.py", line 78, in get_rzero
AttributeError: 'ADC' object has no attribute 'get_resistance'
Code: Select all
import machine, time
from dht22 import DHT22
from mq135 import MQ135
adc3 = machine.ADC(machine.Pin(29))
dht22 = DHT22(machine.Pin(2,machine.Pin.IN,machine.Pin.PULL_UP))
while True:
T, H = dht22.read() # Gets Temp & Hum from dht22.py library
rzero = MQ135.get_rzero(adc3)
corrected_rzero = MQ135.get_corrected_rzero(adc3,T, H)
resistance = MQ135.get_resistance(adc3)
ppm = MQ135.get_ppm(adc3)
corrected_ppm = MQ135.get_corrected_ppm(adc3,T, H)
print("DHT22 Temperature: " + str(T) +"\t Humidity: "+ str(H))
print("MQ135 RZero: " + str(rzero) +"\t Corrected RZero: "+ str(corrected_rzero)+
"\t Resistance: "+ str(resistance) +"\t PPM: "+str(ppm)+
"\t Corrected PPM: "+str(corrected_ppm)+"ppm")
time.sleep(1)Code: Select all
"""Micropython library for dealing with MQ135 gas sensor
Based on Arduino Library developed by G.Krocker (Mad Frog Labs)
and the corrections from balk77 and ViliusKraujutis
More info:
https://hackaday.io/project/3475-sniffing-trinket/log/12363-mq135-arduino-library
https://github.com/ViliusKraujutis/MQ135
https://github.com/balk77/MQ135
"""
import math
import time
from machine import ADC
class MQ135(object):
""" Class for dealing with MQ13 Gas Sensors """
# The load resistance on the board
RLOAD = 10.0
# Calibration resistance at atmospheric CO2 level
RZERO = 76.63
# Parameters for calculating ppm of CO2 from sensor resistance
PARA = 116.6020682
PARB = 2.769034857
# Parameters to model temperature and humidity dependence
CORA = 0.00035
CORB = 0.02718
CORC = 1.39538
CORD = 0.0018
CORE = -0.003333333
CORF = -0.001923077
CORG = 1.130128205
# Atmospheric CO2 level for calibration purposes
ATMOCO2 = 397.13
def __init__(self, pin):
self.pin = pin
def get_correction_factor(self, temperature, humidity):
"""Calculates the correction factor for ambient air temperature and relative humidity
Based on the linearization of the temperature dependency curve
under and above 20 degrees Celsius, asuming a linear dependency on humidity,
provided by Balk77 https://github.com/GeorgK/MQ135/pull/6/files
"""
if temperature < 20:
return self.CORA * temperature * temperature - self.CORB * temperature + self.CORC - (humidity - 33.) * self.CORD
return self.CORE * temperature + self.CORF * humidity + self.CORG
def get_resistance(self):
"""Returns the resistance of the sensor in kOhms // -1 if not value got in pin"""
adc = ADC(self.pin)
value = adc.read_u16()
if value == 0:
return -1
return (1023./value - 1.) * self.RLOAD
def get_corrected_resistance(self, temperature, humidity):
"""Gets the resistance of the sensor corrected for temperature/humidity"""
return self.get_resistance()/ self.get_correction_factor(temperature, humidity)
def get_ppm(self):
"""Returns the ppm of CO2 sensed (assuming only CO2 in the air)"""
return self.PARA * math.pow((self.get_resistance()/ self.RZERO), -self.PARB)
def get_corrected_ppm(self, temperature, humidity):
"""Returns the ppm of CO2 sensed (assuming only CO2 in the air)
corrected for temperature/humidity"""
return self.PARA * math.pow((self.get_corrected_resistance(temperature, humidity)/ self.RZERO), -self.PARB)
def get_rzero(self):
"""Returns the resistance RZero of the sensor (in kOhms) for calibratioin purposes"""
return self.get_resistance() * math.pow((self.ATMOCO2/self.PARA), (1./self.PARB))
def get_corrected_rzero(self, temperature, humidity):
"""Returns the resistance RZero of the sensor (in kOhms) for calibration purposes
corrected for temperature/humidity"""
return self.get_corrected_resistance(temperature, humidity) * math.pow((self.ATMOCO2/self.PARA), (1./self.PARB))