Arduino temperature logger

In this example we will expand the SD card example we did previously and we will add a DS18B20 temperature sensor. We will log the results of the sensor to a file on the SD Card called temp.txt.

Layout

arduino and sdcard and ds18b20

Code

You need to download 2 libraries and copy them into your Arduino libraries folder, this makes life a lot easier.

“DallasTemperature” Library
“1-Wire” Library

#include <SD.h>
#include <OneWire.h>
#include <DallasTemperature.h>

#define DS18B20 7

const int chipSelect = 4;
OneWire ourWire(DS18B20);
DallasTemperature sensors(&ourWire);

void setup()
{

Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect.
}
Serial.print(“Initializing SD card…”);
pinMode(10, OUTPUT);

//init SD card
if (!SD.begin(chipSelect))
{
Serial.println(“Card failed, or not present”);
return;
}
Serial.println(“card initialized.”);
sensors.begin();
}

void loop()
{

sensors.requestTemperatures();
// open the file.
File dataFile = SD.open(“temp.txt”, FILE_WRITE);

// if the file is available, write to it:
if (dataFile)
{
dataFile.println(sensors.getTempCByIndex(0));
dataFile.close();
}
// if the file isn’t open
else
{
Serial.println(“error opening temp.txt”);
}
}

Results

Run the example, then remove the SD Card from your SD Card breakout, connect it to your PC and open the temp.txt and look at the contents

Here is some of the entries in my file

28.19
28.44
28.44
28.44
28.44
28.69
28.69
28.69
28.69
28.87
28.87
28.87
28.87
29.12
29.12
29.12
29.12
29.25

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