SPI with SD card module in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to include the SD library needed for SPI communication with the SD card module.

Arduino

#include <[1]>

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

Drag options to blanks, or click blank then click option'

ASPI.h

BWire.h

CSD.h

DEEPROM.h

Attempts:

3 left

💡 Hint

Common Mistakes

Including SPI.h instead of SD.h

Including Wire.h which is for I2C communication

Forgetting to include any library

The SD library is required to communicate with the SD card module over SPI.

2fill in blank

medium

Complete the code to initialize the SD card on chip select pin 10.

Arduino

const int chipSelect = [1];

void setup() {
  Serial.begin(9600);
  if (!SD.begin(chipSelect)) {
    Serial.println("Initialization failed!");
    return;
  }
  Serial.println("Initialization done.");
}

Drag options to blanks, or click blank then click option'

A4

B7

C13

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using pin 13 which is the SPI clock pin

Using pin 4 which is sometimes used but not standard

Using pin 7 which is unrelated

Pin 10 is commonly used as the chip select pin for SD card modules on Arduino Uno.

3fill in blank

hard

Fix the error in the code to open a file named "test.txt" for writing.

Arduino

File dataFile = SD.[1]("test.txt", FILE_WRITE);

Drag options to blanks, or click blank then click option'

Aopen

BopenFile

CopenNextFile

Attempts:

3 left

💡 Hint

Common Mistakes

Using openFile which does not exist

Using openNextFile which is for directory iteration

Using open with wrong capitalization

The correct function to open a file on the SD card is SD.open().

4fill in blank

hard

Fill both blanks to write the string "Hello" to the file and then close it.

Arduino

File dataFile = SD.open("test.txt", FILE_WRITE);
if (dataFile) {
  dataFile.[1]("Hello");
  dataFile.[2]();
} else {
  Serial.println("Error opening file");
}

Drag options to blanks, or click blank then click option'

Aprint

Bwrite

Cclose

Dflush

Attempts:

3 left

💡 Hint

Common Mistakes

Using write() which writes bytes, not strings

Using flush() instead of close()

Forgetting to close the file

Use print() to write text and close() to close the file properly.

5fill in blank

hard

Fill all three blanks to read from "test.txt" and print each character to Serial until the file ends.

Arduino

File dataFile = SD.open("test.txt");
if (dataFile) {
  while (dataFile.[1]()) {
    char c = dataFile.[2]();
    Serial.[3](c);
  }
  dataFile.close();
} else {
  Serial.println("Error opening file");
}

Drag options to blanks, or click blank then click option'

Aavailable

Bread

Cprint

Dpeek

Attempts:

3 left

💡 Hint

Common Mistakes

Using peek() which only previews data

Using write() instead of print() for Serial output

Not checking if data is available before reading

Use available() to check if data remains, read() to get a character, and print() to output it.

Practice

1. What is the main purpose of using SPI when working with an SD card module on Arduino?

easy

A. To enable fast communication between Arduino and the SD card

B. To power the SD card module

C. To store data permanently on the Arduino board

D. To convert analog signals to digital

Solution

1. Step 1: Understand SPI role

   SPI is a communication protocol that allows fast data transfer between devices.

2. Step 2: Connect Arduino and SD card

   SPI connects Arduino to the SD card module to send and receive data quickly.

3. Final Answer:

   To enable fast communication between Arduino and the SD card -> Option A

4. Quick Check:

   SPI = fast communication [OK]

Hint: SPI is for fast data transfer, not power or storage [OK]

Common Mistakes:

• Confusing SPI with power supply
• Thinking SPI stores data on Arduino
• Mixing SPI with analog-to-digital conversion

2. Which of the following is the correct way to initialize the SD card module using SPI on Arduino if the chip select pin is 10?

easy

A. SD.start(10);

B. SD.begin(10);

C. SD.open(10);

D. SD.init(10);

Solution

1. Step 1: Recall SD library initialization

   The SD library uses SD.begin(chipSelectPin) to start communication.

2. Step 2: Match correct function and parameter

   SD.begin(10) correctly initializes the SD card with pin 10 as chip select.

3. Final Answer:

   SD.begin(10); -> Option B

4. Quick Check:

   SD.begin(pin) initializes SD card [OK]

Hint: Use SD.begin() with chip select pin to start SD card [OK]

Common Mistakes:

• Using SD.start() which does not exist
• Confusing SD.open() with initialization
• Using SD.init() which is not a valid method

3. What will be the output on the Serial Monitor after running this Arduino code snippet?

if (SD.begin(10)) {
  Serial.println("SD card initialized.");
} else {
  Serial.println("Initialization failed.");
}

medium

A. SD card initialized.

B. Initialization failed.

C. Compilation error

D. No output

Solution

1. Step 1: Understand SD.begin() return value

   SD.begin(10) returns true if the SD card initializes successfully.

2. Step 2: Check the if condition and output

   If true, it prints "SD card initialized." to Serial Monitor.

3. Final Answer:

   SD card initialized. -> Option A

4. Quick Check:

   SD.begin(10) true prints initialization message [OK]

Hint: SD.begin() returns true if SD card is ready [OK]

Common Mistakes:

• Assuming SD.begin() always fails
• Expecting no output without Serial.begin() (assumed present)
• Confusing SD.open() with SD.begin()

4. Identify the error in this Arduino code snippet for writing to an SD card:

SD.begin(10);
File dataFile = SD.open("log.txt", FILE_WRITE);
if (dataFile) {
  dataFile.println("Hello World");
}
// Missing dataFile.close();

medium

A. SD.open() is used incorrectly

B. Missing SD.begin() before opening file

C. println() cannot be used with File

D. File is not closed after writing

Solution

1. Step 1: Check file handling steps

   After writing to a file, it must be closed to save data properly.

2. Step 2: Identify missing close()

   The code writes but does not call dataFile.close(), risking data loss.

3. Final Answer:

   File is not closed after writing -> Option D

4. Quick Check:

   Always close files after writing [OK]

Hint: Always close the file after writing to save data [OK]

Common Mistakes:

• Forgetting to call SD.begin() before open
• Thinking println() is invalid for File
• Ignoring file close causes data loss

5. You want to write multiple sensor readings to an SD card file named "data.txt" every 5 seconds. Which approach correctly uses SPI with the SD card module to do this efficiently?

hard

A. Call SD.begin(10) once in setup(), open the file, write readings, close file each time in loop()

B. Call SD.begin(10) once in setup(), open file once in setup(), write readings and close file each time in loop()

C. Call SD.begin(10) once in setup(), open and close the file each time in loop() before writing readings

D. Call SD.begin(10) inside loop(), open file once in setup(), write readings without closing file

Solution

1. Step 1: Understand SD.begin() usage

   SD.begin() should be called once in setup() to initialize the card.

2. Step 2: Manage file open/close in loop()

   Opening and closing the file each time in loop() ensures data is saved and file is not locked.

3. Step 3: Avoid keeping file open across loops

   Keeping file open without closing risks data loss or corruption if power fails.

4. Final Answer:

   Call SD.begin(10) once in setup(), open and close the file each time in loop() before writing readings -> Option C

5. Quick Check:

   Initialize once, open/close file each write [OK]

Hint: Init SD once; open and close file each write cycle [OK]

Common Mistakes:

• Calling SD.begin() repeatedly wastes time
• Leaving file open across loop iterations
• Opening file only once and never closing