Lesson 24--Microduino Digital Tube Thermometer

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Objective

This tutorial will teach you how to use the DS18B20 temperature sensor get the temperature value and display on digital tube.

Equipment

Speaker

第二十四课-DS18B20温度传感器.jpg

DS18B20 is a commonly used temperature sensor, it has the the advantages of small volume, low hardware overhead, strong anti-jamming capability and high precision. Correct connection: Facing the flat side, left is the negative and right is positive. Once the connection is wrong, it will heat up immediately, may burn! At the same time, this is also the cause of the sensor always displays 85℃.

Schematic

第二十四课-Microduino数码管温度计原理图.jpg

Pin Table

Microduino Pin Digital Tube
D2 10(A)
D3 9(B)
D4 1(C)
D5 4(D)
D6 3(E)
D7 6(F)
D8 5(G)
9 2(DP)
D10 8(LED1)
D11 7(LED2)

Program

byte digit0 = 10;	//Ten digits bit 
byte digit1 = 11;	//Single digits bit
byte dotPin = 2;	//Decimal point of digital tube

byte sevenSegmentPins[] = {
  2,3,4,5,6,7,8};	//A,B,C,D,E,F,G's Microduino pin
byte sevenSegment[10][7] =
{
  //a b c d e f g
  { 
    0,0,0,0,0,0,1   }
  ,  // = 0
  { 
    1,0,0,1,1,1,1   }
  ,  // = 1
  { 
    0,0,1,0,0,1,0   }
  ,  // = 2
  { 
    0,0,0,0,1,1,0   }
  ,  // = 3
  { 
    1,0,0,1,1,0,0   }
  ,  // = 4
  { 
    0,1,0,0,1,0,0   }
  ,  // = 5
  { 
    0,1,0,0,0,0,0   }
  ,  // = 6
  { 
    0,0,0,1,1,1,1   }
  ,  // = 7
  { 
    0,0,0,0,0,0,0   }
  ,  // = 8
  { 
    0,0,0,1,1,0,0   }   // = 9
};

void setup() {


  //Initialize all lights up
  pinMode(dotPin, OUTPUT); //pin 2
  pinMode(digit0, OUTPUT); //pin 10
  pinMode(digit1, OUTPUT); //pin 11

  for(int i=0; i<7; i++)
  {
    pinMode(sevenSegmentPins[i], OUTPUT);
  }
  digitalWrite(dotPin, HIGH);
  digitalWrite(digit0, HIGH);
  digitalWrite(digit1, HIGH);

}

//Display number
void segmentWrite(byte digit)
{
  byte pin = 2;
  for (byte i=0; i<7; ++i)
  {
    digitalWrite(pin, sevenSegment[digit][i]);
    ++pin;
  }
}

void loop() {

  int n = analogRead(A0);    //Read the voltage from AO
  int vol = n * (5.0 / 1023.0*100);   //Use a float type variable to store temperature value which was converted from voltage value

  //Get the single digits number
  int sd=vol%10;
  //Get the ten digits number
  int td=vol/10;

  digitalWrite(digit0, LOW);   //Turn off ten digits bit digital tube
  segmentWrite(sd);             //Display single digits bit
  delay(10);                  //Delay 10ms 
  digitalWrite(digit0, HIGH);  //Turn on ten digits bit digital tube
  digitalWrite(digit1, LOW);   //Turn off single digits bit digital tube
  segmentWrite(td);             //Diplay ten digits bit
  delay(10);                  //Dealy 10ms
  digitalWrite(digit1, HIGH);  //Turn on single digital tube

}

Debug

Step 1: Copy the code to IDE and compile it

Step 2: Set up circuit, as follows:

第二十四课-Microduino数码管温度计连接图.jpg

Step 3: Run program

Step 4: Observe the digital tube, find a hot object close to the temperature sensor, the value on digital tube will change.


Result

The temperature sensor closes to the hot object, the value will increase.

Video

http://v.youku.com/v_show/id_XNjgyMzE4ODg4.html