Hello,

Is it possible to not process the calibration each time I started the script ?

I would like to use it with munin. So I do only one calibration.

Thanks

Hi, may i know how you able to get this value data format:{ x, y, slope}; point1: (lg200, 0.21), point2: (lg10000, -0.59) . FYI, the -0.59 value cannot be found on the datasheet and does not form the curve with the LPG gas

Hello,

Is it the same program for MQ2 and MQ9 sensors ?

I am using both on my Rpi with MCP3008 and I change the channel (0 for MQ2 and 1 for MQ9).

Aborts immediately after run. Pulled "mq = MQ()" outside of the try statement to see what was going on. Got the following error. The GPIO pins are reading voltage, but whatever's going inside of MCP3008, it returns zero.

Traceback (most recent call last):
File "example2.py", line 4, in
mq = MQ()
File "/home/pi/Desktop/CO_sensor/Raspberry-Pi-Gas-Sensor-MQ/mq.py", line 48, in init
self.Ro = self.MQCalibration(self.MQ_PIN)
File "/home/pi/Desktop/CO_sensor/Raspberry-Pi-Gas-Sensor-MQ/mq.py", line 84, in MQCalibration
val += self.MQResistanceCalculation(self.adc.read(mq_pin))
File "/home/pi/Desktop/CO_sensor/Raspberry-Pi-Gas-Sensor-MQ/mq.py", line 69, in MQResistanceCalculation
return float(self.RL_VALUE*(1023.0-raw_adc)/float(raw_adc));
ZeroDivisionError: float division by zero

Hardware: Raspberry Pi Zero, MQ-2, MCP3008 (20307)

I'm trying to modify the mq.py settings for this sensor:
http://www.sensorica.ru/pdf/MQ-136.pdf
But I don't understand how to find this value:
RO_CLEAN_AIR_FACTOR.
I setted this value to 1.5
After I calculated this Curve:
self.H2SCurve = [1,0.176,-0.306]

But when I execute the example.py after calibrating it send me the Ro and exit with "Abort by user".

code gets abort after 1st print.

I try to change MQ-135 to MG-811 on board. When i used MQ-135, the data is appear. But when i change to MG-811, the data is gone. Can you explained it?

Hi,

I don't have the MCP3008 laying around and want to use the ads1115 ADC.

But I don't have any clue how to add this in the code?

Would this be possible to add this to the code (commented ofcourse)

Hi,
I realized that there is a little mistake on the code. In python math.log() takes log on base 2, not on base 10. math.log10() should be used for log based on 10.

    def MQGetPercentage(self, rs_ro_ratio, pcurve):
        return (math.pow(10,( ((math.log(rs_ro_ratio)-pcurve[1])/ pcurve[2]) + pcurve[0])))

Therefore the code above should be updated as like the below.

    def MQGetPercentage(self, rs_ro_ratio, pcurve):
        return (math.pow(10,( ((math.log10(rs_ro_ratio)-pcurve[1])/ pcurve[2]) + pcurve[0])))