ESP8266 TWI SH1106 and DS18B20 Temperature Sensor

The DS18B20 is a digital thermometer able to converts surrounding temperature between -55°C and +125°C. It operates between 3.0VDC to 5.5VDC which is suitable for hobbyist and industrial applications. It implements the One-Wire digital communication protocol, requires only one bi-directional I/O pin for data and command transmission or reception. Its ROM Search feature allow multiple DS18X20 sensors to connect on a single wire bus.

 

Temperature Reading via ESP8266 D0 Pin

Commanding and decoding data from this sensor is easy. The manufacturers offer a lot of example programs written in Assembly or C language. For Arduino users, there are a lot of libraries available, created by various authors.

Using Arduino IDE, we can use this sensor from scratch by installing some related libraries. I use the  OneWire and DallasTemperature library. Because its C++ function is easily readable and short. Go into the DallasTemprature and open the simple.ino file. To test this sensor and see the result over serial port.

 

Arduino simple.ino Sketch

 

However I modify this example to work with a 128x64 OLED display, SH1106. So it needs these libraries:

1. OneWire
2.  DallasTemperature
3.  Wire
4.  Adafruit_GFX
5.  Adafruit_SH110X

In this example, the ESP-12E read temperature data from a single DS18B20 connects to D0 pin. The result will show on the SH1106 OLED display.

DS18B20 Pin Configurations

 

There are many device packages for this sensor. For hobbyists, it's suitable to use a transistor-like TO-92 package. However, there are some Arduino modules for this sensor available at very low cost. That's below 1USD.

Its DQ or data pin is open-drain. So we need to add a weak pull up resistor between 4.7kΩ and 10kΩ depending on its range.
 

ESP8266 Arduino Source Code:

// Include the libraries we need
#include <OneWire.h>
#include <DallasTemperature.h>

/* Data wire is plugged into 
port 2 on the Arduino */
#define ONE_WIRE_BUS D0

/* Setup a oneWire instance to communicate 
with any OneWire devices 
(not just Maxim/Dallas temperature ICs) */
OneWire oneWire(ONE_WIRE_BUS);

/* Pass our oneWire reference 
to Dallas Temperature. */
DallasTemperature sensors(&oneWire);

// OLED Section
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SH110X.h>

/* Uncomment the initialize the I2C address , 
uncomment only one, If you get a totally blank 
screen try the other*/
#define i2c_Address 0x3c 
/*initialize with the I2C addr 0x3D 
Typically Adafruit OLED's */
//#define i2c_Address 0x3d 

#define SCREEN_WIDTH 128 
#define SCREEN_HEIGHT 64 
#define OLED_RESET -1   
Adafruit_SH1106G display = 
Adafruit_SH1106G(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
/*
 * The setup function. We only start the sensors here
 */
void setup(void)
{
  // start serial port
  Serial.begin(9600);
  Serial.println("Dallas Temperature IC Control Library Demo");

  // Start up the library
  sensors.begin();

  delay(250); // wait for the OLED to power up
  display.begin(i2c_Address, true); // Address 0x3C default
  // Clear the buffer.
  display.clearDisplay();
 
  display.setTextColor(SH110X_WHITE);
  display.setCursor(0, 8);
  display.setTextSize(3);
  display.println("ESP8266");
  display.println("NodeMCU");
  display.display();
  delay(5000);
  display.clearDisplay();
  
  display.setCursor(10, 8);
  display.setTextSize(3);
  display.println("SH1106");
  display.println("  OLED");
  display.display();
  delay(5000);
  display.clearDisplay();

  display.setCursor(10, 8);
  display.setTextSize(3);
  display.println("Temp");
  display.println("Sensor");
  display.display();
  delay(5000);
  display.clearDisplay();
}

/*
 * Main function, get and show the temperature
 */
void loop(void)
{
  
  Serial.print("Requesting temperatures...");
  sensors.requestTemperatures(); 
  Serial.println("DONE");
  delay(1500);
  
  float tempC = sensors.getTempCByIndex(0);

  // Check if reading was successful
  if (tempC != DEVICE_DISCONNECTED_C)
  {
    Serial.print("Temperature for the device 1 (index 0) is: ");
    Serial.println(tempC);
  }
  else
  {
    Serial.println("Error: Could not read temperature data");
  }
  display.setTextColor(SH110X_WHITE);
  display.setCursor(16, 0);
  display.setTextSize(2);
  display.println("Temp (C):");
  display.setCursor(16, 32);
  display.setTextSize(3);
  display.println(tempC);
  display.display();
  delay(900);
  // Clear the buffer.
  display.clearDisplay();
  
}

Pictures:

I use my own ESP8266 TWI Prototype Board to test this example.

 

ESP8266 TWI Prototype Board

 

ESP8266 TWI Prototype Board

 

ESP8266 TWI Prototype Board

 Video: