III Gallery

Outcome

Intention

My roommate, Meilin, cares a lot about how to live a healthier life. If possible, she would definitely drink warm water which is better for stomach. We have a water boiler in the kitchen, but the problem is she tended to forget to come back to kitchen and get water on time. For so many times, when she finally realized that the boiled water was available, after one or two hours, the water has already cooled off.

Move up Delete Move down

Context

I want create an IoT product which can let me know when the water has been boiled and the temperature is suitable for us to drink (the temperature world still be too hot right after being boiled).

Move up Delete Move down

Process

To sense the water temperature, I would need a temperature sensor, and since the alarm sound would be noising I decided to use LED light and SMS message (through IFTT) to notice Meilin that the water in the boiler is ready to drink.

Move up Delete Move down

Product

The IoT particle is built up with:

Breadboard x1
Low voltage temperature sensor TMP37 x1
103 Resistor x1
LED lights x4
Resistor (brown/black/red) x1
Jumper wire x14
Connect wire x3

Move up Delete Move down

Outcome

The IoT particle is built up with:

Breadboard x1
Low voltage temperature sensor TMP37 x1
103 Resistor x1
LED lights x4
Resistor (brown/black/red) x1
Jumper wire x14
Connect wire x3

Video is available here:

https://drive.google.com/open?id=0B5mItdEDyTHUZ2xrbmZTaFZYYlU

Move up Delete Move down

Show Advanced Options

Move up Delete Move down

int sensorPin = A0;
int sensorVal = 0;
int baselineTemp = 10;
int number = 4;
int LedPin [4] = {D0, D1, D2, D3};
float temperature = 0;

void setup(){
  Serial.begin(9600);
  for (int x=0; x<5; x++){
    pinMode(x, OUTPUT);
    digitalWrite(x, LOW);

  }
  Particle.variable ("sensorValue",&sensorVal,INT);
}

void loop(){
  sensorVal = analogRead(sensorPin);
  Serial.print (sensorVal);
  Serial.print ("ADC");
  float Voltage = (sensorVal/1024.0)*5.0;
  Serial.print (Voltage);
  Serial.print ("Volts,");
  temperature = (Voltage * 4) + 7;
  Serial.print (temperature);
  Serial.print ("degrees C");
  if (temperature < baselineTemp){
    digitalWrite(LedPin[0], LOW);
    digitalWrite(LedPin[1], LOW);
    digitalWrite(LedPin[2], LOW);
    digitalWrite(LedPin[3], LOW);
    Particle.publish ("TempCold", "cold");
  }
   else if (temperature >= baselineTemp && temperature < baselineTemp+10){
     digitalWrite(LedPin[0], HIGH);
     digitalWrite(LedPin[1], LOW);
     digitalWrite(LedPin[2], LOW);
     digitalWrite(LedPin[3], LOW);
     Particle.publish ("TempCool", "cool");
   }
   else if (temperature >= baselineTemp+10 && temperature < baselineTemp+20){
     digitalWrite(LedPin[0], HIGH);
     digitalWrite(LedPin[1], HIGH);
     digitalWrite(LedPin[2], LOW);
     digitalWrite(LedPin[3], LOW);
     Particle.publish ("TempWarm", "warm");
   }
   else if (temperature >= baselineTemp+20 && temperature < baselineTemp+30){
     digitalWrite(LedPin[0], HIGH);
     digitalWrite(LedPin[1], HIGH);
     digitalWrite(LedPin[2], HIGH);
     digitalWrite(LedPin[3], LOW);
     Particle.publish ("TempPerfect", "perfect");
   }
   else if (temperature >= baselineTemp+30 && temperature < baselineTemp+40){
     digitalWrite(LedPin[0], HIGH);
     digitalWrite(LedPin[1], HIGH);
     digitalWrite(LedPin[2], HIGH);
     digitalWrite(LedPin[3], HIGH);
     Particle.publish ("TempHot", "hot");
   }
   delay(1000);
  }

Show Advanced Options

Move up Delete Move down

Reflection

Different sensors need different code — even TMP36 is different from TMP37

The tutorial I studied online is using TMP36 as an example to build up a temperature sensitive product. The sensor I picked up from IDeAte lad is TMP37. Though there is only a tiny difference in their names, it greatly changed the equation part in the code in which I need to transfer the number sensor reads to voltage and finally to temperature in Celsius. The fact is that TMP36 have an output scale factor of 10 mV/°C and TMP37 provides an output scale factor of 20 mV/°C.

Detailed difference can be found here:

http://www.analog.com/media/en/technical-documentation/data-sheets/TMP35_36_37.pdf

2. Understand how temperature sensor works

The sensor's working base is the voltage that's read across the diode. The temperature rises when the voltage increases.