so does 37164 represents the scaling factor and -3.178 the exponent?
Vir
@Vir said:

What does 37143 represents, Rs? and -3.178 is a second value from your regression method, but what about the first value?
Can you elaborate on ppm line, please
Vir

here the formula is a simplification of this:

float Vrl = val * ( 5.00 / 1024.0 ); // V
float Rs = 20000 * ( 5.00 - Vrl) / Vrl ; // Ohm
int ratio = Rs/Ro;
ppm = 37143 * pow (ratio, -3.178);

@bhavika said:

I am confused with MiCS 4514 sensor. What I had done is :

using MiCS quick start evaluation board, measured ADC value
calculated Vout and from that calculated R0.
Rs/R0 concentration gives me high value, which is not possible, My data is as follows
clean air file is used for the purpose of R0 value
https://drive.google.com/file/d/0B8sF8a6FHoseWjhWOHRoYzIxakk/view?usp=sharing
and Polluted file is used to calculate the actual pollution
https://drive.google.com/file/d/0B8sF8a6FHoseR1BnclhCUHdibEU/view?usp=sharing

I am confused. Please help me

I am confused by the formula you are using, could you please explain?
Pollution NO2 = (POWER((RS/R0)*(1/POWER(10,0.8068)),(1/1.01)))

Pollution CO = POWER((RS/R0)*(1/POWER(10 , 0.5476)),(1/-0.8497)))

is the actual formula like this?:

pollution = POWER((ratio *(1/POWER(10, curve[0])),(1/[curve[1])))

This is different than any other formulas discussed in this thread...
Vir

What does 37143 represents, Rs? and -3.178 is a second value from your regression method, but what about the first value?
Can you elaborate on ppm line, please
Vir

here the formula is a simplification of this:

float Vrl = val * ( 5.00 / 1024.0 ); // V
float Rs = 20000 * ( 5.00 - Vrl) / Vrl ; // Ohm
int ratio = Rs/Ro;
ppm = 37143 * pow (ratio, -3.178);

Hi, It all make sense, I am just confused that in your code once your multiply and once you divide...

case CO:
{
if(ratio1 < 0.01) ratio1 = 0.01;
if(ratio1 > 3) ratio1 = 3;
//c = pow(10, 0.6) / pow(ratio1, 1.2);
** c = pow(ratio1, -1.179)4.385; //mod by jack*
break;
}
case NO2:
{
if(ratio2 < 0.07) ratio2 = 0.07;
if(ratio2 > 40) ratio2 = 40;
//c = ratio2 / pow(10, 0.8);
** c = pow(ratio2, 1.007)/6.855; //mod by jack**
break;
}
SO, what is the actual formula?

Vir

@epierre said:

I'm now testing the MICS-6814 (3 sensors in one) given for :
Carbon monoxide CO 1 -1000ppm
**Nitrogen dioxide NO2 0.05 –10ppm **
Ethanol C2H5OH 10 –500ppm
Hydrogen H2 1 –1000ppm
Ammonia NH3 1 –500ppm
Methane CH4 >1000ppm
Propane C3H8 >1000ppm
Iso-butane C4H10 >1000ppm

Datasheet maionly speaks on CO, NO2 and NH3:
http://www.seeedstudio.com/wiki/images/1/10/MiCS-6814_Datasheet.pdf

Here is are scripts:
http://www.seeedstudio.com/wiki/Grove_-_Multichannel_Gas_Sensor

http://www.seeedstudio.com/wiki/images/1/10/MiCS-6814_Datasheet.pdf

Some readings:

The concentration of NH3 is 0.99 ppm
The concentration of CO is 1.20 ppm
The concentration of NO2 is 0.15 ppm
The concentration of C3H8 is 1000.04 ppm
The concentration of C4H10 is 999.98 ppm
The concentration of CH4 is 2991.14 ppm
The concentration of H2 is 1.09 ppm
The concentration of C2H5OH is 1.40 ppm

I guess I'll make a script soon...