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Arduino - Display Temperature from LM35 Sensor on OLED
In this tutorial, we are going to learn how to read the temperature from LM35 sensor and display it on an OLED.
Hardware Required
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some links direct to products from our own brand, DIYables.
Additionally, some links direct to products from our own brand, DIYables.
About OLED and LM35 Temperature Sensor
If you do not know about OLED and LM35 Temperature Sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:
- Arduino - OLED tutorial
- Arduino - LM35 Temperature Sensor tutorial
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
Arduino Code - LM35 Temperature Sensor - OLED
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-display-temperature-from-lm35-sensor-on-oled
*/
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define ADC_VREF_mV 5000.0 // in millivolt
#define ADC_RESOLUTION 1024.0
#define PIN_LM35 A0 // pin connected to LM35 temperature sensor
Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C
String tempString;
void setup() {
Serial.begin(9600);
// initialize OLED display with address 0x3C for 128x64
if (!oled.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
Serial.println(F("SSD1306 allocation failed"));
while (true);
}
delay(2000); // wait for initializing
oled.clearDisplay(); // clear display
oled.setTextSize(2); // text size
oled.setTextColor(WHITE); // text color
oled.setCursor(0, 10); // position to display
tempString.reserve(10); // to avoid fragmenting memory when using String
}
void loop() {
// get the ADC value from the LM35 temperature sensor
int adcVal = analogRead(PIN_LM35);
// convert the ADC value to voltage in millivolt
float milliVolt = adcVal * (ADC_VREF_mV / ADC_RESOLUTION);
// convert the voltage to the temperature in Celsius
float tempC = milliVolt / 10;
tempString = String(tempC, 2); // two decimal places
tempString += char(247) + String("C");
Serial.println(tempString); // print the temperature in Celsius to Serial Monitor
oledDisplayCenter(tempString); // display temperature on OLED
}
void oledDisplayCenter(String text) {
int16_t x1;
int16_t y1;
uint16_t width;
uint16_t height;
oled.getTextBounds(text, 0, 0, &x1, &y1, &width, &height);
// display on horizontal and vertical center
oled.clearDisplay(); // clear display
oled.setCursor((SCREEN_WIDTH - width) / 2, (SCREEN_HEIGHT - height) / 2);
oled.println(text); // text to display
oled.display();
}
Quick Steps
- Open Arduino IDE on your PC.
- Navigate to the Libraries icon on the left bar of the Arduino IDE.
- Search “SSD1306”, then find the SSD1306 library by Adafruit
- Click Install button to install the library.
- You will be asked for intalling some other library dependencies
- Click Install All button to install all library dependencies.
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Put the sensor on hot and cold water, or grasp the sensor by your hand
- See the result on OLED and Serial Monitor
※ NOTE THAT:
The about code automatically horizontal and vertical center aligns the text on OLED display
Video Tutorial
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