Tag:

LM35

Arduino Due and LM35 temperature sensor

by shedboy71 3rd January 2018

written by shedboy71

In this example we will connect an LM35 temperature sensor to our Arduino Due</p><p>The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±1/4°C at room temperature and ±3/4°C over a full -55 to +150°C temperature range

Here is a picture of the pins, its important to get these correct or you can damage the sensor

Schematics

Very simple to connect

Vcc is 3v3
Gnd is any Gnd and out goes to Arduino A0, you can see this below

Code

[codesyntax lang=”cpp”]

const int analogIn = A0;

int RawValue= 0;
double Voltage = 0;
double tempC = 0;
double tempF = 0;

void setup(){ 
Serial.begin(9600);
}

void loop(){

RawValue = analogRead(analogIn);
Voltage = (RawValue / 1023.0) * 3300; // 5000 to get millivots.
tempC = Voltage * 0.1; 
tempF = (tempC * 1.8) + 32; // conver to F 
Serial.print("Raw Value = " ); // shows pre-scaled value 
Serial.print(RawValue); 
Serial.print("\t milli volts = "); // shows the voltage measured 
Serial.print(Voltage,0); //
Serial.print("\t Temperature in C = ");
Serial.print(tempC,1);
Serial.print("\t Temperature in F = ");
Serial.println(tempF,1);
delay(500); 
}

[/codesyntax]

Output

Open the serial monitor

Raw Value = 68 milli volts = 219 Temperature in C = 21.9 Temperature in F = 71.5
Raw Value = 70 milli volts = 226 Temperature in C = 22.6 Temperature in F = 72.6
Raw Value = 71 milli volts = 229 Temperature in C = 22.9 Temperature in F = 73.2
Raw Value = 72 milli volts = 232 Temperature in C = 23.2 Temperature in F = 73.8
Raw Value = 73 milli volts = 235 Temperature in C = 23.5 Temperature in F = 74.4
Raw Value = 74 milli volts = 239 Temperature in C = 23.9 Temperature in F = 75.0
Raw Value = 75 milli volts = 242 Temperature in C = 24.2 Temperature in F = 75.5
Raw Value = 76 milli volts = 245 Temperature in C = 24.5 Temperature in F = 76.1
Raw Value = 77 milli volts = 248 Temperature in C = 24.8 Temperature in F = 76.7

Links

LM35 datasheet
5PCS LM35D Temperature Sensor TO92 Packing

3rd January 2018 0 comment

MBed

STM32 Nucleo and LM35 temperature sensor

by shedboy71 3rd January 2018

written by shedboy71

In this example we will connect an LM35 temperature sensor to our Nucleo board and we will be using the MBed compiler

The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±1/4°C at room temperature and ±3/4°C over a full -55 to +150°C temperature range

Here is a picture of the pins, its important to get these correct or you can damage the sensor

Schematics and Connection

Very simple to connect

Vcc is 3v3
Gnd is any Gnd and output goes to Nucleo A0, you can see this below

nucleo and lm35

Code

This example is for the mbed online compiler – https://os.mbed.com/compiler/

[codesyntax lang=”cpp”]

#include "mbed.h"

AnalogIn LM35(PA_0); //Setting pin PA0 (A0) as Anlog Input
Serial pc(SERIAL_TX, SERIAL_RX); //Create an object of Serial Class

int main()
{
float tempC,tempF,a[10],avg;
int i;

while(1)
{

avg=0;
for(i=0;i<10;i++)
{
a[i]=LM35.read();
wait(.02);
}
for(i=0;i<10;i++)
{
avg=avg+(a[i]/10);
}


tempC=(avg*3.685503686*100);
tempF=(9.0*tempC)/5.0 + 32.0;
pc.printf("temperature = %.0f ^C\r\n", tempC);

wait(1); 
}
}

[/codesyntax]

Output

Using a terminal program you should see something like this

temperature = 21 ^C
temperature = 21 ^C
temperature = 21 ^C
temperature = 21 ^C
temperature = 23 ^C
temperature = 24 ^C
temperature = 25 ^C
temperature = 25 ^C
temperature = 26 ^C
temperature = 26 ^C
temperature = 26 ^C

Links

KEYES LM35 analog temperature sensor module

3rd January 2018 0 comment

Espruino

Espruino LM35 temperature sensor example

by shedboy71 14th October 2016

written by shedboy71

In this example we will connect an LM35 temperature sensor to our Espruino

Here is a picture of the pins, its important to get these correct or you can damage the sensor

lm35-temperature-sensor-pinout

I purchased a small module, which looks like this. This was clearly labelled and helps avoid any mistakes with wiring, I also prefer using cables to modules rather than breadboards

lm35-module

Schematics and Parts

You will need

Espruino
LM35 sensor or module
Hook up wire (dupont cables)

Very simple to connect Vcc is 3.3v, Gnd is any Gnd and out goes to Espruino A1, you can see this below

espruino-and-lm35_bb

Code

[codesyntax lang=”javascript”]

function getTemp() {
  var val = analogRead(A1); // read voltage
  var millivolts = val * 3300;
  var celsius = millivolts/10;
  return celsius; // and return the temperature
}

function checkTemp() {
 var temp = getTemp();
 console.log("Temperature: " + temp + " C");
}
setInterval(checkTemp, 1000);

[/codesyntax]

Results

Here are the results via the console window of the Espruino Web IDE

Temperature: 17.64431219958 C
Temperature: 17.72487983520 C
Temperature: 18.20828564888 C
Temperature: 20.22247653925 C
Temperature: 21.59212634470 C
Temperature: 22.55893797207 C
Temperature: 23.28404669260 C
Temperature: 24.08972304875 C
Temperature: 24.41199359121 C
Temperature: 24.73426413366 C

Links

LM35 datasheet
5PCS LM35D Temperature Sensor TO92 Packing

14th October 2016 0 comment