Published October 28, 2016 © GPL3+

IoT Breathalyzer with Cayenne, ESP8266, and MQ3 Sensor

Scientifically prove your intoxication in style with this internet connected breathalyzer!

IntermediateWork in progress5 hours3,107

IoT Breathalyzer with Cayenne, ESP8266, and MQ3 Sensor

Things used in this project

Hardware components

Espressif ESP8266 ESP-12E

MQ3 Alcohol Gas Sensor

Linear Regulator (7805)

3.3v Voltage Regulator

SparkFun FTDI Basic Breakout - 3.3V

Software apps and online services

myDevices Cayenne

Arduino IDE

Story

About This Project

The idea for this project came when I found a cheap sensor online that claimed to measure alcohol concentration in the air. Who hasn't at some point wanted to use a breathalyzer, to see to a scientific degree just how intoxicated they were?

Police around the world use breathalyzers to obtain suspected drunk drivers' BAC. These breathalyzers give accurate and reproducible readings, but cost hundreds of dollars.

The MQ3 sensor only costs a couple bucks, but it does not give accurate, nor reproducible BAC readings. In other words, don't use this sensor to decide if you can drive or not. However, we can still have fun comparing relative values between friends.

The Cayenne platform and an ESP8266 are used to connect the MQ-3 sensor to the internet so data can be viewed and gathered over time.

Hardware

The device needs to be portable and durable if it should be used while under the influence. The 11.1 Wh/hr lipo battery provides about 8 hours of continuous use. All the components are stuck to the battery pack with thick double sided tape. I hope this provides some shock absorption in case of drops. The enclosure is made of two 3mm aluminum plates bolted together. Aluminum is a great material to work with because it cuts and drills easily, but that also means that it is easily scratched as seen by the pictures. Regardless, it will protect the battery and electronics in most situations and I think it gives the device a rugged feel.

Arduino Sketch

The arduino sketch is pretty straightforward. The template provided in the cayenne dashboard provides a very good starting point. The first virtual input sends current readings from the sensor to the dashboard. I added a second channel/input to keep track of the highest reading obtained, aka the "high score". If the cayenne devs are reading this, I wish there were more input types other than luminosity, voltage, etc. I don't see why the data has to be tied to a unit at all. Lastly, there's an http server running so that the board firmware can be updated over the air.

Sketch is available at https://github.com/dpeters1/IoT-Breathalyzer

Cayenne Integration

The Cayenne dashboard provides current alcohol concentration, highest reading, and a graph of readings with respect to time.

Photos

1 / 9

Code

Arduino Sketch

#define CAYENNE_DEBUG         // Uncomment to show debug messages
#define CAYENNE_PRINT Serial  // Comment this out to disable prints and save space

#include <CayenneDefines.h>
#include <BlynkSimpleEsp8266.h>
#include <CayenneWiFiClient.h>
#include <CayenneClient.h>
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <ESP8266HTTPUpdateServer.h>

// Cayenne authentication token. This is obtained from the Cayenne Dashboard.
const char* token = "rtibpy87tp";
const char* ssid = "Wu-Tang LAN";
const char* password = "allstream11";
const char* host = "esp8266-webupdate";

int reading = 0;
int highScore = 0;
int lastState = 0;

ESP8266WebServer httpServer(80);
ESP8266HTTPUpdateServer httpUpdater;

void setup()
{
  Serial.begin(115200);
  Serial.println("Booting Sketch...");
  pinMode(A0, INPUT);

  /* // Cayenne.begin takes care of this
  WiFi.mode(WIFI_AP_STA);
  WiFi.begin(ssid, password);
  while(WiFi.waitForConnectResult() != WL_CONNECTED){
    WiFi.begin(ssid, password);
    Serial.println("WiFi failed, retrying.");
  }
 */
  Cayenne.begin(token, ssid, password);

  MDNS.begin(host);
  httpUpdater.setup(&httpServer);
  httpServer.begin();

  MDNS.addService("http", "tcp", 80);
  Serial.printf("HTTPUpdateServer ready! Open http://%s.local/update in your browser\n", host);
}

void loop()
{
  httpServer.handleClient();
  Cayenne.run();
}

  CAYENNE_OUT(V0)
{
  reading = analogRead(A0);
  if(reading > highScore){
    highScore = reading;
  }
  Cayenne.virtualWrite(V0, reading, DISTANCE, MILLIMETERS);
}

 CAYENNE_OUT(V1)
{
  Cayenne.virtualWrite(V1, highScore, DISTANCE, MILLIMETERS);
}

CAYENNE_OUT(V2)
{
  Cayenne.virtualWrite(V2, reading, DISTANCE, MILLIMETERS);
}
CAYENNE_IN(V3)
{
  int state = getValue.asInt();
  if(state != lastState){
    highScore = 0;
    lastState = state;
  }
  
}

Credits

Dominic Peters

2 projects • 2 followers

IoT Breathalyzer with Cayenne, ESP8266, and MQ3 Sensor

Things used in this project

Hardware components

Software apps and online services

Story

About This Project

Hardware

Arduino Sketch

Cayenne Integration

Photos

Schematics

Schematic

Code

Arduino Sketch

Credits

Dominic Peters

Comments

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IoT Breathalyzer with Cayenne, ESP8266, and MQ3 Sensor

IoT Breathalyzer with Cayenne, ESP8266, and MQ3 Sensor

Things used in this project

Hardware components

Software apps and online services

Story

About This Project

Hardware

Arduino Sketch

Cayenne Integration

Photos

Schematics

Schematic

Code

Arduino Sketch

Credits

Dominic Peters

Comments

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