# Learn Embedded Programming [Step by Step]

## Gas Sensor (MQ-9) :

MQ-9 Gas Sensor is one kind of semiconductor which has very lower conductivity in open air. But in Carbon Monoxide, Methane and LPG gas it has good conductivity. By using ADC of pic microcontroller we can measure it. Let's take a look on MQ-9 sensor .

## Basic Concepts :

The MQ-9 sensor will be connected with a pic microcntroller and a buzzer will also be connected with microcontroller. When LPG gas will be detected in sensor, it will provide voltage into microcontroller's RA1 pin(ADC). It will provide reading more than 590. At this situation microcontroller will turn on the buzzer and LED. That's the basic concept.

## ADC(Analog to Digital Converter ) :

We need a basic knowledge about ADC. Let's  take a look at here :

Basically ADC works like as a voltage divider. According to voltage It produce output.

bit 5 : VCFG0: Voltage Reference Configuration bit (VREF- source)
1 = VREF- (AN2)
0 = VSS or 0 volt

bit 4 :VCFG0: Voltage Reference Configuration bit (VREF+ source)
1 = VREF+ (AN3)
0 = VDD or 5volt

We will set  VCFG0[bit 5]=0and VCFG0[bit4]=0. So we will get highest value 5volt[1023] and lowest value 0volt[0].The ADCON1 is a 10 bit register that means  2 to the power 10  is it's highest counting capacity and result is 1024. So this register can count from 0 to 1023. When 0 volt, we get reading at RA1 pin  0. When 5 volt, we get reading at RA1 pin 1023. It means 5volt equivalent to 1023 .

If  5 volt    equal    reading 1023 .

So 1  volt   equal    reading 1023/5
[When LPG Gas detect MQ-9 Sensor provide more than 2.93 volt at AO Pin]
So 3 volt equal  reading  (1023/5)*2.93 =599 When we get reading 599 at ADC channel, we understand  that sensor detects LPG. So it makes PORTB.F6 pin high and Buzzer turns on .

## MikroC Source Code :

double source=0;
char txt[15];
void main() {
ADCON1=0x0D;         // Configure RA1 pin as input
CMCON=7;
TRISB.F6=0;

while(1){
PORTB.F6=0;
if(source>600){
delay_ms(500);
PORTB.F6=1;
}
}
}

## Thank You!

1. Thank you sir. My comment option hasn't been working for a long time. Suddenly I've found it working and I'm making reply, sir.

1. Can you plz mail me the programme used in this programme?
My mail id is stephenzion96@gmail.com

1. I have uploaded all I have got. Thank you.

2. Sir i use pic16f877a and it has a lot unusual errors...Do pic18 family has same issue ?

1. Although It's a late reply. But you know I have to response. If your aim is to make project for university exam then use same MCU same circuit as I had done. Thank you.

3. I tried to simulate the circuit with the given program in software with mq-9 sensor(I added the sensor in the library) but its not working... I made the hex file burned it in the chip but its not simulating. Any idea where i go wrong?

1. it was supposed to work. While I tried It took some times to work as far as I remember.

4. what is mean double source=0;

1. I initialized a variable double type that's it.

5. This comment has been removed by a blog administrator.

6. can i get the whole code ?

Mail: keremarcaa@gmail.com

8. That's very good try, reach the best gas company which is located near you to buy quality gas leak detector.

1. Ha ha. Yeah Thank you!

9. There is no other completing that will hold up to the higher temperatures of a gas stove as effectively as the porcelain will. Best auto ignition gas stove

1. Actually I have not that much idea. Thank you.

10. Around the 1930's, the gas stoves the coal and wood stoves two to one. 3 burner gas stove with glass top

12. The two dining establishments beneath the bridge are Snoopy’s and Doc’s. Snoopy’s seems to be the much more remarkably regarded, but we do not comprehend why. Snoopys is just a fried fish-shack. You order at the counter and select up your unique meals served on paper plates. It is money only, and it has no bar just beer. Doc’s has waiters, real plates, and a complete bar. They each have terrific sunset views about the lagoon, but neither appeared to have air-conditioning. Flow Meter LC

13. I got what you mean , a debt of gratitude is in order for posting .Woh I am cheerful to discover this site through google.
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