Arduino Breathalyzer

Forum 2005-2010 (read only) General Exhibition
1

using the basic code from [Arduino]Tutorial Alcohol Gas Sensor MQ-3 + Arduino and Building a Breathalyzer with MQ-3 and Arduino - Daniel Andrade i have got the beginning stages of the breathalyzer prototyped.

obvious changes, moved leds to 3-11 to get away from the 2 pin (tx) otherwise the final led stays lit up when using serial monitor.

switched to a 10k resistor for easier calibration.

todo list....

add a "tare" function to allow for easier, more sensitive BAC readings.

add 4 seven segment displays to allow for portability.

"grid" the leds so that they use less pins.

board it and box it.

i am a noob so any help would be greatly appreciated.

code to come in next post.

2 
const int analogPin = 0; // the pin that the potentiometer is attached to
const int ledCount = 10; // the number of LEDs in the bar graph
unsigned int val = 0;
unsigned char PIN = 0;

int ledPins[] = {
11,10,9,8,7,6,5,4,3,2 // Here we have the number of LEDs to use in the BarGraph
}; 

void setup() {
{
  Serial.begin(9600);
  pinMode(PIN,INPUT);
}
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
pinMode(ledPins[thisLed], OUTPUT);
}}

void loop() {

  {
  val = analogRead(PIN);
  Serial.println(val);
  delay(2000);
} 
  
  
  //This is the code to light up LED's
int sensorReading = analogRead(analogPin);

int ledLevel = map(sensorReading, 500, 1023, 0, ledCount);

for (int thisLed = 0; thisLed < ledCount; thisLed++) {

if (thisLed < ledLevel) {
digitalWrite(ledPins[thisLed], HIGH);
}

else {
digitalWrite(ledPins[thisLed], LOW);
} }}
3

subscribed, this is relevant to my interests

4

I think a lot of people are interested in calibrating the MQ-3 alcohol sensor to make a workable breathalyzer. I spent a lot of time on this and did a big writeup on the project here:

http://nootropicdesign.com/projectlab/2010/09/17/arduino-breathalyzer/

Bottom line is that it's really hard to do! Any ideas are very welcome.