jensmalmgren
Published © GPL3+

Jens Temperature Sensor Coaster

This coaster detects the temperature of a cup. You get a signal when it is ready to drink.

IntermediateFull instructions provided5,761
Jens Temperature Sensor Coaster

Things used in this project

Hardware components

Arduino Nano R3
Arduino Nano R3
×1
Blue LED 455nm 3.8v 20mA
×1
Red LED 625nm 1.8v 2..5mA
×1
Green LED 565nm 2.2v 2...5mA
×1
Resistor 560 ohm 0.4w
×1
Resistor 68 ohm 0.4w
×1
Resistor 680 ohm 0.4w
×1
Shrink Tube
×1
Rubber feets sticker 10 mm diameter 2 mm high
×4
Temperature Sensor
Temperature Sensor
×1

Software apps and online services

Visual Studio 2015
Microsoft Visual Studio 2015
Fusion 360
Autodesk Fusion 360

Hand tools and fabrication machines

3D Printer, ABS Filament
Soldering iron (generic)
Soldering iron (generic)
Sidecutter

Story

Read more

Custom parts and enclosures

STL of the bottom of the coaster

Run this file through your slicer to produce gcode to be printed with your 3d printer

Error uploading file to Sketchfab.

STL of top of the coaster

Run this file through your slicer to produce gcode to be printed with your 3d printer

Error uploading file to Sketchfab.

STL of the holder of the thermometer

Run this file through your slicer to produce gcode to be printed with your 3d printer

Error uploading file to Sketchfab.

Schematics

Circuit Diagram

Diagram of the circuit
Coaster schem rpxfpkwn3n

Bread Board Layout

Before putting together you can try on a breadboard
Coaster bb oodmtzuvuc

Code

The sketch for the coaster

Arduino
This program is loded into the coaster it is reading the temperature sensor and lighting the LEDs based on the given ranges.
#include <EEPROM.h>

#define AREF 3.3         // we tie 3.3V to ARef and measure it with a multimeter!

//Vout TMP36 > A1
//3.3V > V+ TMP36 > AREF
//GND TMP36 > GND
//D6 > Piezo > GND
//D7 > Blue Led (+), Blue Led (-) > 60 Ohm > GND
//D8 > Green Led (+), Green Led (-) > 560 Ohm > GND
//D9 > Red Led (+), Red Led (-) > 640 Ohm > GND

int iPinTemperature = 1;
int iTemperatureReading;
int iPinLedRed = 9;
int iPinLedGreen = 8;
int iPinLedBlue = 7;
int iPinBuzzer = 6;
String strSerialInput = "";
bool bSerialInputComplete = false;
float fTopTemperature = 100;
float fBottomTemperature = 0;
int iEEPROMTopTemperature = 0;
int iEEPROMBottomTemperature = 4;
int iEEPROMDisplayCelcius = 8;
int iEEPROMPlayTopTemperatureSound = 9;
int iEEPROMPlayBottomTemperatureSound = 10;
bool bPlayTopTemperatureSound = false;
bool bPlayBottomTemperatureSound = false;
bool bTempDisplaysCelcius = true;
float fPreviousTemperature = 0;
// Number of average temperatures in celcius
#define AVGC 13
#define POSCOUNT 10
float fArrTemps[AVGC]; // Array used to calculate the average temperature
float fArrTempsD[AVGC]; // Array used to calculate the average delta temperature
int iLEDConfigCurrent = 0; // 1 = Red, 0 = Green, -1 = Blue
int iLEDConfigPrevious = 0; // 1 = Red, 0 = Green, -1 = Blue
bool bLEDsActive = false;
bool bLEDsBlink = false;
float fAverageTemp;
float fAverageTempD;
int iDeltaPositiveCount;
bool bInitAverage = true;
int iAvgIndex;
long lMilliSecondsSinceBeep = -1;
long iMilliSecondsSinceBeepCount = 50000;
long iMilliSecondsSinceLastSwitchCount = 900000;
long lMilliSecondsSinceLastSwitch = iMilliSecondsSinceLastSwitchCount;
   
void setup(void)
{
  // We'll send debugging information via the Serial monitor
  Serial.begin(9600);
  Serial.println("Setup");  
 
  // If you want to set the aref to something other than 5v
  analogReference(EXTERNAL);
  pinMode(iPinLedRed, OUTPUT);
  pinMode(iPinLedGreen, OUTPUT);
  pinMode(iPinLedBlue, OUTPUT);

  strSerialInput.reserve(20);

  long lTop = EEPROMReadlong(iEEPROMTopTemperature);
  if (lTop < 0 || lTop > 10000)
  {
    lTop = 4500;
  }
  long lBottom = EEPROMReadlong(iEEPROMBottomTemperature);
  if (lBottom < 0 || lBottom > 10000)
  {
    lBottom = 3900;
  }

  if (lTop < lBottom)
  {
    lTop = 4500;
    lBottom = 3900;
  }
  fTopTemperature = (float)lTop / (float)100;
  fBottomTemperature = (float)lBottom / (float)100;
  bTempDisplaysCelcius = EEPROM.read(iEEPROMDisplayCelcius) == 1;
  
  bPlayTopTemperatureSound = EEPROM.read(iEEPROMPlayTopTemperatureSound) == 1;
  bPlayBottomTemperatureSound = EEPROM.read(iEEPROMPlayBottomTemperatureSound) == 1;
}
 
 
void loop(void)
{
  if (bSerialInputComplete)
  {
    Serial.println(strSerialInput);
    strSerialInput = "";
    bSerialInputComplete = false;
  }
  
  iTemperatureReading = analogRead(iPinTemperature);  
  // Converting temperature voltage to temperature using AREF
  float fTemperatureVoltage = iTemperatureReading * AREF;
  fTemperatureVoltage /= 1024.0;
  float fTemperatureC = (fTemperatureVoltage - 0.5) * 100 ;  //converting from 10 mv per degree with 500 mV offset to degrees ((fTemperatureVoltage - 500mV) times 100

  // Initialize average arrays etc
  if (bInitAverage)
  {
    for (int j = 0; j < AVGC; j++)
    {
      fArrTemps[j] = fTemperatureC;
      fArrTempsD[j] = (float)-0.01;
    }
    bInitAverage = false;
    iAvgIndex = 0;
    fAverageTemp = fTemperatureC;
    fPreviousTemperature = fTemperatureC;
    bLEDsActive = true;
    lMilliSecondsSinceBeep = millis();
    iLEDConfigPrevious = -1;
  }

  // Point to next average in the arrays
  iAvgIndex++;
  if (iAvgIndex > AVGC - 1)
  {
    iAvgIndex = 0;
  }

  fArrTemps[iAvgIndex] = fTemperatureC;

  // Calculate averages
  fAverageTemp = 0;
  int iPosCount = 0;
  for (int j = 0; j < AVGC; j++)
  {
    if (fArrTempsD[j] > (float)0.0)
    {
      iPosCount++;
    }
    fAverageTemp += fArrTemps[j];
    fAverageTempD += fArrTempsD[j];
  }

  fAverageTemp = fAverageTemp / (float)AVGC;
  fAverageTempD = fAverageTempD / (float)AVGC;
 
  Serial.print("[it:"); Serial.print(fTemperatureC);Serial.print(",tt:");
  Serial.print(fTopTemperature);Serial.print(",bt:");
  Serial.print(fBottomTemperature);Serial.print(",dc:");
  Serial.print(bTempDisplaysCelcius);
  Serial.print(",at:");Serial.print(fAverageTemp);
  Serial.print(",pt:");Serial.print(bPlayTopTemperatureSound);
  Serial.print(",pb:");Serial.print(bPlayBottomTemperatureSound);
  Serial.println("]");

  if (fAverageTemp >= fTopTemperature)
  {
    iLEDConfigCurrent = 1; // Red
  }
  if (fAverageTemp <= fBottomTemperature)
  {
    iLEDConfigCurrent = -1; // Blue
  }
  if (fAverageTemp > fBottomTemperature && fAverageTemp < fTopTemperature)
  {
    iLEDConfigCurrent = 0; // Green
  }

  if (iLEDConfigCurrent >= 0 || (iLEDConfigCurrent == -1 && fAverageTempD > 0 && iPosCount >= POSCOUNT))
  {
    lMilliSecondsSinceLastSwitch = millis();
  }
  
  bLEDsActive = ((millis() - lMilliSecondsSinceLastSwitch) < iMilliSecondsSinceLastSwitchCount);

  if (iLEDConfigPrevious == 1 && iLEDConfigCurrent == 0)
  {
      PlayUp();
  }

  if (iLEDConfigPrevious == 0 && iLEDConfigCurrent == -1)
  {
      PlayDown();
  }

  if (!bLEDsActive || (fAverageTempD > 0 && iPosCount >= POSCOUNT && !bLEDsBlink))
  {
    digitalWrite(iPinLedRed, LOW);
    digitalWrite(iPinLedGreen, LOW);
    digitalWrite(iPinLedBlue, LOW);
  }
  else
  {
    if (iLEDConfigCurrent == 1)
    {
      digitalWrite(iPinLedRed, HIGH);
      digitalWrite(iPinLedGreen, LOW);
      digitalWrite(iPinLedBlue, LOW);
    }
    if (iLEDConfigCurrent == 0)
    {
      digitalWrite(iPinLedRed, LOW);
      digitalWrite(iPinLedGreen, HIGH);
      digitalWrite(iPinLedBlue, LOW);
    }
    if (iLEDConfigCurrent == -1)
    {
      digitalWrite(iPinLedRed, LOW);
      digitalWrite(iPinLedGreen, LOW);
      digitalWrite(iPinLedBlue, HIGH);
    }
  }

  fArrTempsD[iAvgIndex] = fAverageTemp - fPreviousTemperature;
  fPreviousTemperature = fAverageTemp;
  iLEDConfigPrevious = iLEDConfigCurrent;
  bLEDsBlink = !bLEDsBlink;
  delay(450);
}

void serialEvent()
{
  while (Serial.available())
  {
    // get the new byte:
    char inChar = (char)Serial.read();
    // add it to the strSerialInput:
    strSerialInput += inChar;
    // if the incoming character is a newline, set a flag so the main loop can
    // do something about it:
    if (inChar == '\n')
    {
      bSerialInputComplete = true;

      if (strSerialInput.startsWith("tt:"))
      {
          strSerialInput = strSerialInput.substring(3);
          fTopTemperature = strSerialInput.toFloat();
          EEPROMWritelong(iEEPROMTopTemperature, (long)(fTopTemperature * (float)100));
      }

      if (strSerialInput.startsWith("bt:"))
      {
          strSerialInput = strSerialInput.substring(3);
          fBottomTemperature = strSerialInput.toFloat();
          EEPROMWritelong(iEEPROMBottomTemperature, (long)(fBottomTemperature * (float)100));
      }

      bTempDisplaysCelcius = ParseSerialOfBoolIfMatchSetEEPROMAndReturnBool("dc:", bTempDisplaysCelcius, iEEPROMDisplayCelcius);
      bPlayTopTemperatureSound = ParseSerialOfBoolIfMatchSetEEPROMAndReturnBool("pt:", bPlayTopTemperatureSound, iEEPROMPlayTopTemperatureSound);
      bPlayBottomTemperatureSound = ParseSerialOfBoolIfMatchSetEEPROMAndReturnBool("pb:", bPlayBottomTemperatureSound, iEEPROMPlayBottomTemperatureSound);
    }
  }
}

bool ParseSerialOfBoolIfMatchSetEEPROMAndReturnBool(String ip_strCommand, bool ip_bOriginalValue, int ip_iEEPROM_Location)
{
  bool _bResult = ip_bOriginalValue;
  if (strSerialInput.startsWith(ip_strCommand))
  {
    strSerialInput = strSerialInput.substring(3);
    _bResult = (strSerialInput == "1\n");
    EEPROM.write(ip_iEEPROM_Location, _bResult);
  }
  return _bResult;
}

void EEPROMWritelong(int address, long value)
{
  byte by;
  for(int i=0;i< 4;i++) {
    by = (value >> ((3-i)*8)) & 0x000000ff; 
    EEPROM.write(address+i, by);
  }
}


long EEPROMReadlong(long address)
{
  long lo=0;

  for(int i=0;i< 3;i++){
    lo += EEPROM.read(address+i);
    lo = lo << 8;
  }
  lo += EEPROM.read(address+3);
  return lo;
}

void PlayUp()
{
  if (bPlayTopTemperatureSound && (millis() - lMilliSecondsSinceBeep > iMilliSecondsSinceBeepCount))
  { 
    tone(iPinBuzzer, 440, 100);
    delay(100);
    tone(iPinBuzzer, 880, 100);
    delay(100);
    tone(iPinBuzzer, 1760, 100);
    lMilliSecondsSinceBeep = millis();
  }
}

void PlayDown()
{
  if (bPlayBottomTemperatureSound && (millis() - lMilliSecondsSinceBeep > iMilliSecondsSinceBeepCount))
  { 
    tone(iPinBuzzer, 1760, 100);
    delay(100);
    tone(iPinBuzzer, 880, 100);
    delay(100);
    tone(iPinBuzzer, 440, 100);
    lMilliSecondsSinceBeep = millis();
  }
}

The configuration program made with c# and Visual Studio 2017 community edition

C#
This program displays the settings of the coaster and makes it possible to change the settings. Here is an archive with the solution and the icons, c# etc
No preview (download only).

Credits

jensmalmgren

jensmalmgren

0 projects • 2 followers

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