Lesson 15--Microduino "Make sense of warm cup circuit"

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Last lesson introduced how to use LM35D, this lesson will show you how to make a analog thermal cup combined with Microduino.


  • Microduino-Core
  • Microduino-FT232R
  • Other hardware equipment
    • Breadboard Jumper one box
    • Breadboard one piece
    • LM35D temperature sensor one
    • RGB LED one
    • 450Ω resistor one

Experimental schematic


LM35's connection doesn't change, just add a common anode RGB LED.


void setup() {
  Serial.begin(115200);         //Set hte baud rate as 115200
  for(int i=2;i<5;i++)          //Set LED output
    pinMode(i, OUTPUT);  

void loop() {

  int n = analogRead(A0);    //Read voltage value from A0 port

  float temp = n * (5.0 / 1023.0*100);   //Use a float variable to save temperature value which was calculated from voltage.

  if (temp<21)  //Low temperature setting, and led display
    digitalWrite(4, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(2, LOW);
  else if (temp>=21 && temp<=23)  //Middle temperature setting, && means "and" operation
    digitalWrite(4, HIGH);
    digitalWrite(3, LOW);
    digitalWrite(2, HIGH);
  else if (temp>23)   //High temperature setting
    digitalWrite(4, LOW);
    digitalWrite(3, HIGH);
    digitalWrite(2, HIGH);
  Serial.println(temp); //Output the temperature from serial port
  delay(1000);         //Wait for 1s and refresh the data


The temperature is set to low temperature, middle temperature and high temperature three range. When the temperature in the low temperature zone, RGB display a green light, blue light display in the middle temperature zone,and high temperature red light. Simulates a temperature sensing cup.