DIY Low‑Cost Portable Thermometer with Android Integration

Necessary tools and machines

	Soldering iron (generic)
	Solder Wire, Lead Free

Apps and online services

About this project

Measuring body temperature with non-contact / contactless like a thermo gun. I created this project because Thermo Gun now is very expensive, so I must get alternative to make DIY. And the purpose is make with low budget version.

Wiring Connection (Hardware)

MLX 90614 have I2C communication, so in Arduino Nano use pin A4 & A5

Prepare Programming (Software)

For library MLX90614 I use adafruit library, you can Open Arduino IDE and menu Tools -> Manage Libraries -> search MLX90614. and click Adafruit MLX90614 Library then click install in Library Manager

Test Example From Library

To make sure that mlx90614 sensor can work, open Arduino IDE, Click File -> Examples -> Adafruit MLX90614 Library -> mlxtest.

Upload then see serial Monitor, you can see Ambient temperature and object temperature.

Prepare Circuit, OTG, and 3D Print Cover

After sample MLX90614 code work, prepare circuit between arduino nano and mlx90614 sensor like a picture. For OTG you can make DIY with Male Microusb and Male Miniusb.

Cover Portable Thermometer can download file 3D in https://grabcad.com/library/portable-thermometer-box-1 and print with your 3Dprint Machine

Install App Portable Thermometer From Playstore

You can search in playstore "portable Thermometer" or you can click this link Portable Thermometer or you can scan this qr-code

Running Portable Thermometer

How to running Portable thermometer

• Connect device in your smartphone with OTG.
• Active OTG Connection in your smartphone
• Run application
• Click check now to check body temperature

Video Project Portable Thermometer

Code

• Portable Thermometer Arduino Code

Portable Thermometer Arduino CodeArduino

/*
 * MLX90614 Send to OTG
 * sekolahrobot@gmail.com
 */

#define LED 13
#include <Wire.h>
#include <Adafruit_MLX90614.h>

Adafruit_MLX90614 mlx = Adafruit_MLX90614();

unsigned long previousMillis;
int interval = 50;
char i;
int data = 0;
void setup() {
    Serial.begin(9600);
    mlx.begin(); 
    pinMode(LED, OUTPUT);
}

void loop() {
    if (Serial.available() > 0) {
        i = Serial.read();
        switch (i) {
            case '0':
                digitalWrite(LED, LOW);
                data = 0;
                break;
            case '1':
                digitalWrite(LED, HIGH);
                data = 1;
                break;
        }
    }
if (data==1)
  {
      if (millis() - previousMillis >= interval) {
          previousMillis = millis();
          Serial.print(mlx.readAmbientTempC()); 
          Serial.print(";");
          Serial.println(mlx.readObjectTempC());
      }
  }

}

Custom parts and enclosures

Schematics