Introduction: Arduino Temperature Led Bar
The leds show the temp between 16 to 40 c degrees.
enjoy!
Step 1: Shopping List
Step 2: Parts List
3 green led
2 yellow led
3 orange led
3 red led
11 330Ω resistors
1 breadboard
1 Arduino Uno
1 LM35 Temperature Sensor
15 jumper cables (male to male)
Step 3: Setup
5 Comments
2 years ago
I am having trouble using a DS18B20 sensor with this project, I can't get the LED to work.
Any help?
Question 4 years ago on Introduction
Could this be adapted to show 20-150 Celsius using a standard automotive oil temperature sensor (I think they’re NTC thermistors)?
7 years ago
Try this Code:
// Serial Temperature Sensor and visual output through LEDs
float temperature = 0; // store data in a variable with coma, temperature, whose value is initially "null"
//---------------------------------------------------
int analogPin = 0; // // initialize as input ANALOG read (the SENSOR's pin)
const int ledCount = 10; // the number of LEDs in the bar graph
int ledPins[] = { 1, 2, 3, 4, 5, 6, 7,}; // an array of pin numbers to which LEDs are attached
//--------------------------------------------------------------------------
//setup
void setup()
{
Serial.begin(9600); //open communication with the serial port
Serial.println("LM35 Thermometer "); //print a starting message
analogReference(INTERNAL); // THIS FUNCTION IS REALLY IMPORTANT WHEN USING
// analogRead() INPUPTS. USING THE ANALOG INPUT, THE
// FUNCTION WILL RETURN VALUES FROM 0 TO 1023.
// The options for this function are:
//DEFAULT: the default analog reference of 5 volts
//INTERNAL: an in-built reference, equal to 1.1 volts
//EXTERNAL: the voltage applied to the AREF pin is
//used as a reference
//SINCE THE MAXIMUM VALUE THE SENSOR
//CAN HANDLE IS 1VOLT, WE HAVE TO USE "INTERNAL"
//INTERNAL ? means voltages of 1.1v or higher from the
//temperature sensor will give an analog reading of
//1023. Anything lower will give a lower value, e.g. 0.55
//volts will give 512. The sensor range is from 0C to 100C
//therefore 0C will be calculated when the sensor records 0volts
}
//function
void printTenths(int value) {
//printTenths function is used to show the fraction of the temperature reading 18,2C
Serial.print(value / 10); // prints a value of 123 as 12.3
Serial.print(".");
Serial.println(value % 100); //print the value after the decimal point "write 100 for a 2nd digit precision 0,00[ch8243]
//---------------------------------------------------
// loop over the pin array and set them all to output:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
pinMode(ledPins[thisLed], OUTPUT);
//--------------------------------------------------------------------------
}
}
void loop() { //this loop allows to reduce the error reading from analogig sensors (like the LM35) introducing an
//averaged value of the temperature, using the variable SPAN value 20. It means that 20 readings of
//the temperature are taken and than the output is divided by 20
int span = 20; //set up the number of readings
int aRead = 0; //store an initial value of 0 for the anaologic read
for (int i = 0; i < span; i++) { //for 20 times do the following process
aRead = aRead+analogRead(analogPin); //read the analog from pin0 and sum it to 0(aRead)
}
aRead = aRead / 20; //average final value
//according to a simple mathematic proportion aRead : Temperature = 1023 : 100
//infact 1023 is the maximum analog value as well as 100 is the maximum analogic temperature
//The sensor is reading temperature according to Voltage variations (0 to 1Volts)
//therefore 0to1Volts corresponds to 0to1023 analogic values. But because we set up a function option
//calle "INTERNAL" (that assigs 1.1Volts to the maximum snalogic range 1024) it is required to
//write the following equation:
temperature = ((aRead*100*1.1)/1023)*10; // convert analog signal into temperature
//than we can print the temperature on the monitor together with the analogic value detected by the LM35
Serial.print("Analog in reading: ");
Serial.print(long(aRead));
// print temperature value on serial monitor
Serial.print(" - Calculated Temp: ");
printTenths(long(temperature));
delay(1000); //time lag before next printed temperature
//---------------------------------------------------
// read the SENSOR:
int sensorReading = long(aRead);
// map the result to a range from 0 to the number of LEDs:
int ledLevel = map(sensorReading, 170, 270, 0, ledCount);
// loop over the LED array:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
// if the array element's index is less than ledLevel,
// turn the pin for this element on:
if (thisLed < ledLevel) {
digitalWrite(ledPins[thisLed], HIGH);
}
// turn off all pins higher than the ledLevel:
else {
digitalWrite(ledPins[thisLed], LOW);
}
//--------------------------------------------------------------------------
}
}
Reply 7 years ago
THX.
7 years ago on Introduction
Nice arduino project.