{"id":42299,"date":"2017-09-08T12:05:35","date_gmt":"2017-09-08T12:05:35","guid":{"rendered":"http:\/\/randomnerdtutorials.com\/?p=42299"},"modified":"2022-09-20T15:16:34","modified_gmt":"2022-09-20T15:16:34","slug":"guide-to-sd-card-module-with-arduino","status":"publish","type":"post","link":"https:\/\/randomnerdtutorials.com\/guide-to-sd-card-module-with-arduino\/","title":{"rendered":"Guide to SD Card Module with Arduino"},"content":{"rendered":"\n

In this post we\u2019re going to show you how to use an SD card module with Arduino to read and write files on an SD card.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

For an Arduino project with the SD card module read our blog post: Arduino temperature data logger with SD card<\/a>.<\/p>\n\n\n\n

Introducing the SD Card module<\/h2>\n\n\n\n

The SD card module is specially useful for projects that require data logging.<\/p>\n\n\n\n

The Arduino can create a file in an SD card to write and save data using the SD<\/strong> library.<\/p>\n\n\n\n

There are different models from different suppliers, but they all work in a similar way, using the SPI communication protocol. The module used in this tutorial is the one shown in figure below (front and back view).<\/p>\n\n\n\n

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This module works with micro SD card.<\/p>\n\n\n\n

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Where to buy?<\/h3>\n\n\n\n

The SD card module is a very cheap and you can find one for approximately $1 – check prices on Maker Advisor<\/a>.<\/p>\n\n\n\n

Pin wiring<\/h3>\n\n\n\n

The table below shows how you should wire the SD card module to your Arduino<\/p>\n\n\n\n

SD card module <\/strong><\/td>Wiring to Arduino Uno<\/strong><\/td>Wiring to Arduino Mega<\/strong><\/td><\/tr>
VCC<\/td>3.3V or 5V (check module\u2019s datasheet)<\/td>3.3V or 5V (check module\u2019s datasheet)<\/td><\/tr>
CS<\/td>4<\/td>53<\/td><\/tr>
MOSI<\/td>11<\/td>51<\/td><\/tr>
CLK<\/td>13<\/td>52<\/td><\/tr>
MISO<\/td>12<\/td>50<\/td><\/tr>
GND<\/td>GND<\/td>GND<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Note<\/strong>: different Arduino boards have different SPI pins. If you\u2019re using another Arduino board, check the Arduino official documentation<\/a>.<\/p>\n\n\n\n

Preparing the SD card<\/h2>\n\n\n\n

The first step when using the SD card module with Arduino is formatting the SD card as FAT16 or FAT32. Follow the instructions below.<\/p>\n\n\n\n

1)<\/strong> To format the SD card, insert it in your computer. Go to My Computer<\/strong> and right click on the SD card<\/strong>. Select Format<\/strong> as shown in figure below.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

2)<\/strong> A new window pops up. Select FAT32<\/strong>, press Start<\/strong> to initialize the formatting process and follow the onscreen instructions.<\/p>\n\n\n\n

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Testing the SD card module<\/h2>\n\n\n\n

Insert the formatted SD card in the SD card module.<\/p>\n\n\n\n

Connect the SD card module to the Arduino as shown in the circuit schematics below or check Pin Wiring<\/strong> in previous section.<\/p>\n\n\n\n

\"\"<\/a><\/figure><\/div>\n\n\n\n

Note:<\/strong> depending on the module you\u2019re using, the pins may be in a different order.<\/p>\n\n\n\n

Code – CardInfo<\/h3>\n\n\n\n

To make sure everything is wired correctly and the SD card is working properly, in the Arduino IDE window go to File<\/strong>> Examples<\/strong> > SD<\/strong> > CardInfo<\/strong>.<\/p>\n\n\n\n

Upload the code to your Arduino board. Make sure you have the right board and COM port selected.<\/p>\n\n\n\n

Open the Serial Monitor at a baud rate of 9600 and you should see your SD card information.<\/p>\n\n\n\n

If everything is working properly you’ll see a similar message on the serial monitor.<\/p>\n\n\n\n

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Read and write to the SD card<\/h2>\n\n\n\n

The SD<\/span> library provides useful functions for easily write in and read from the SD card.<\/p>\n\n\n\n

To write and read from the SD card, first you need to include the SPI<\/span> and SD<\/span> libraries:<\/p>\n\n\n\n

#include <SPI.h>\n#include <SD.h><\/code><\/pre>\n\n\n\n
You also have to initialize the SD card module at the Chip Select (CS) pin – in our case, pin 4.<\/p>\n\n\n\n
SD.begin(4);<\/code><\/pre>\n\n\n\n
To open a new file in the SD card, you need to create a file<\/span> object that refers to your data file. For example:<\/p>\n\n\n\n
dataFile = SD.open(\"data.txt\", FILE_WRITE);<\/code><\/pre>\n\n\n\n
The first parameter of this function is the name of the file, data.txt<\/span>, and the FILE_WRITE<\/span> ;argument enables you to read and write into the file.<\/p>\n\n\n\n
This line of code creates a file called data.txt<\/strong> on your SD card. If the data.txt<\/strong> file already exists,  Arduino will open the file instead of creating another one.<\/p>\n\n\n\n
To write data to the currently open file, you use:<\/p>\n\n\n\n
dataFile.write(data);<\/code><\/pre>\n\n\n\n
In which the dataFile<\/span> is the file object created previously and the data<\/span> is what you want to write in the file.<\/p>\n\n\n\n
You can also use the print()<\/span> or println()<\/span> functions to print data into the file:<\/p>\n\n\n\n
dataFile.print(data);\ndataFile.println(data); \/\/ followed by a new line<\/code><\/pre>\n\n\n\n
To read the data saved on your file:<\/p>\n\n\n\n
dataFile.read();<\/code><\/pre>\n\n\n\n
You can only write within a file at once, so you need to close a file before proceeding to the next one. To close the data.txt<\/strong> file we’ve just created:<\/p>\n\n\n\n
SD.close(\"data.txt\");<\/code><\/pre>\n\n\n\n
The argument of this function is the file you want to close, in this case data.txt<\/strong>.<\/p>\n\n\n\n
For a complete sketch on how to read and write, in your Arduino IDE go to File<\/strong>> Examples<\/strong> > SD<\/strong> > ReadWrite.<\/strong><\/p>\n\n\n\n
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Wrapping Up<\/h2>\n\n\n\n
This was just a quick introduction to the SD card module with the Arduino.<\/p>\n\n\n\n
Make sure you check the following blog post for a data logging project example using the SD card module with Arduino: <\/p>\n\n\n\n