Joseph LamCharlton Buckler
Published © CC BY

Temperature Measurement & Real-Time Display

Two Particle Photons are used to power a temperature sensor and OLED display. The temp sensor records the ambient temp at 30 sec intervals.

IntermediateFull instructions provided6 hours213
Temperature Measurement & Real-Time Display

Things used in this project

Hardware components

Photon
Particle Photon
×2
Male/Male Jumper Wires
×10
Adafruit SSD1306 OLED Display
×1
Resistor 4.75k ohm
Resistor 4.75k ohm
×1
Solderless Breadboard Half Size
Solderless Breadboard Half Size
×2
Temperature Sensor
Temperature Sensor
×1
USB-A to Mini-USB Cable
USB-A to Mini-USB Cable
×2

Software apps and online services

Maker service
IFTTT Maker service
Google Sheets
Google Sheets

Story

Read more

Schematics

Temperature Sensor

This is the schematic for the photon and temperature circuit.

Temperature Sensor

Screen shot 2018 11 18 at 1 05 08 am pnyezlyznv

OLED Display

This is the schematic for the photon and Adafruit OLED display.

OLED Display

Screen shot 2018 11 18 at 1 04 12 am eyhoht2qvt

Transient Temperature Sensor Performance

Transient temperature performance whmo3gd2of

Code

Temperature Sensor

C/C++
This code controls the temperature sensor and the photon paired with it. Note that the code contains the libray "OneWire.h".
// This #include statement was automatically added by the Particle IDE.
#include <OneWire.h>

OneWire ds = OneWire(D4);  // 1-wire signal on pin D4

unsigned long lastUpdate = 0;

float lastTemp;

void setup() {
  Serial.begin(9600);
  // Set up 'power' pins, comment out if not used!
  pinMode(D3, OUTPUT);
  pinMode(D5, OUTPUT);
  digitalWrite(D3, LOW);
  digitalWrite(D5, HIGH);
  pinMode(D7,OUTPUT);
  Particle.subscribe("receivetemp", myHandler, "420043000851363136363935");
}

void myHandler(const char *event, const char *data){
    if (strcmp(data, "1")==0){
        digitalWrite(D7, HIGH);
        delay(1000);
        digitalWrite(D7, LOW);
    }
}
// up to here, it is the same as the address acanner
// we need a few more variables for this example

void loop(void) {
  byte i;
  byte present = 0;
  byte type_s;
  byte data[12];
  byte addr[8];
  float celsius, fahrenheit;

  if ( !ds.search(addr)) {
    Serial.println("No more addresses.");
    Serial.println();
    ds.reset_search();
    delay(250);
    return;
  }

  // The order is changed a bit in this example
  // first the returned address is printed

  Serial.print("ROM =");
  for( i = 0; i < 8; i++) {
    Serial.write(' ');
    Serial.print(addr[i], HEX);
  }

  // second the CRC is checked, on fail,
  // print error and just return to try again

  if (OneWire::crc8(addr, 7) != addr[7]) {
      Serial.println("CRC is not valid!");
      return;
  }
  Serial.println();

  // we have a good address at this point
  // what kind of chip do we have?
  // we will set a type_s value for known types or just return

  // the first ROM byte indicates which chip
  switch (addr[0]) {
    case 0x10:
      Serial.println("  Chip = DS1820/DS18S20");
      type_s = 1;
      break;
    case 0x28:
      Serial.println("  Chip = DS18B20");
      type_s = 0;
      break;
    case 0x22:
      Serial.println("  Chip = DS1822");
      type_s = 0;
      break;
    case 0x26:
      Serial.println("  Chip = DS2438");
      type_s = 2;
      break;
    default:
      Serial.println("Unknown device type.");
      return;
  }

  // this device has temp so let's read it

  ds.reset();               // first clear the 1-wire bus
  ds.select(addr);          // now select the device we just found
  // ds.write(0x44, 1);     // tell it to start a conversion, with parasite power on at the end
  ds.write(0x44, 0);        // or start conversion in powered mode (bus finishes low)

  // just wait a second while the conversion takes place
  // different chips have different conversion times, check the specs, 1 sec is worse case + 250ms
  // you could also communicate with other devices if you like but you would need
  // to already know their address to select them.

  delay(1000);     // maybe 750ms is enough, maybe not, wait 1 sec for conversion

  // we might do a ds.depower() (parasite) here, but the reset will take care of it.

  // first make sure current values are in the scratch pad

  present = ds.reset();
  ds.select(addr);
  ds.write(0xB8,0);         // Recall Memory 0
  ds.write(0x00,0);         // Recall Memory 0

  // now read the scratch pad

  present = ds.reset();
  ds.select(addr);
  ds.write(0xBE,0);         // Read Scratchpad
  if (type_s == 2) {
    ds.write(0x00,0);       // The DS2438 needs a page# to read
  }

  // transfer and print the values

  Serial.print("  Data = ");
  Serial.print(present, HEX);
  Serial.print(" ");
  for ( i = 0; i < 9; i++) {           // we need 9 bytes
    data[i] = ds.read();
    Serial.print(data[i], HEX);
    Serial.print(" ");
  }
  Serial.print(" CRC=");
  Serial.print(OneWire::crc8(data, 8), HEX);
  Serial.println();

  // Convert the data to actual temperature
  // because the result is a 16 bit signed integer, it should
  // be stored to an "int16_t" type, which is always 16 bits
  // even when compiled on a 32 bit processor.
  int16_t raw = (data[1] << 8) | data[0];
  if (type_s == 2) raw = (data[2] << 8) | data[1];
  byte cfg = (data[4] & 0x60);

  switch (type_s) {
    case 1:
      raw = raw << 3; // 9 bit resolution default
      if (data[7] == 0x10) {
        // "count remain" gives full 12 bit resolution
        raw = (raw & 0xFFF0) + 12 - data[6];
      }
      celsius = (float)raw * 0.0625;
      break;
    case 0:
      // at lower res, the low bits are undefined, so let's zero them
      if (cfg == 0x00) raw = raw & ~7;  // 9 bit resolution, 93.75 ms
      if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
      if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
      // default is 12 bit resolution, 750 ms conversion time
      celsius = (float)raw * 0.0625;
      break;

    case 2:
      data[1] = (data[1] >> 3) & 0x1f;
      if (data[2] > 127) {
        celsius = (float)data[2] - ((float)data[1] * .03125);
      }else{
        celsius = (float)data[2] + ((float)data[1] * .03125);
      }
  }

  // remove random errors
  if((((celsius <= 0 && celsius > -1) && lastTemp > 5)) || celsius > 125) {
      celsius = lastTemp;
  }

  fahrenheit = celsius * 1.8 + 32.0;
  lastTemp = celsius;
  Serial.print("  Temperature = ");
  Serial.print(celsius);
  Serial.print(" Celsius, ");
  Serial.print(fahrenheit);
  Serial.println(" Fahrenheit");

  // now that we have the readings, we can publish them to the cloud
  String temperature = String(fahrenheit); // store temp in "temperature" string
  Particle.publish("Xtemperature/3171_MEGR", temperature); // publish to cloud
  delay(30000); // 30 second delay //every 1 second is "1000"
}

OLED Display Code

C/C++
This code powers the Adafruit SSD1306 OLED display and the accompanying photon. Note that the code contains the library "Adafruit_SSD1306.h".
// This #include statement was automatically added by the Particle IDE.
#include <Adafruit_SSD1306.h>

//OLED Screen code:

//#include "Adafruit_SSD1306/Adafruit_SSD1306.h"

#define OLED_DC     D3
#define OLED_CS     D4
#define OLED_RESET  D5

char temp[9];
String tempO;

Adafruit_SSD1306 display(OLED_DC, OLED_RESET, OLED_CS);

int ledon = 1;
int flashd7 = 0;
void setup()  
{
   
    Particle.subscribe("Xtemperature/3171_MEGR", myHandler);
    
    display.begin(SSD1306_SWITCHCAPVCC);
    display.clearDisplay();
    display.display();

}


void loop() 
{
   
    display.clearDisplay();
    display.setTextColor(WHITE);
    display.setTextSize(1);
    display.setCursor(0,0); 
    Time.zone(-4);
    display.print(Time.timeStr().c_str());
    display.setCursor(0,20); 
    display.printf("Inside Temp:  %0.4s F", temp);
    display.display();
    delay(5000);
    if(flashd7 == 1) {
        Particle.publish("receivetemp", "1");
        flashd7 = 0;
    }
}


void myHandler(const char *event, const char *data)
{
flashd7 = 1;
    strcpy(temp,data);


}

Credits

Joseph Lam

Joseph Lam

1 project • 0 followers
Charlton Buckler

Charlton Buckler

1 project • 0 followers

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