SD card module wiring in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output when reading a file from SD card?

Consider this Arduino code snippet that reads from a file on an SD card. What will be printed on the Serial Monitor?

Arduino

#include <SD.h>
const int chipSelect = 10;
void setup() {
  Serial.begin(9600);
  if (!SD.begin(chipSelect)) {
    Serial.println("Initialization failed!");
    return;
  }
  File dataFile = SD.open("test.txt");
  if (dataFile) {
    while (dataFile.available()) {
      Serial.write(dataFile.read());
    }
    dataFile.close();
  } else {
    Serial.println("Error opening test.txt");
  }
}
void loop() {}

A Initialization failed!

B Hello World!

C Error opening test.txt

D No output

💡 Hint

Check if the SD card is properly initialized and the file exists.

If the SD card is wired correctly and the file 'test.txt' contains 'Hello World!', the program prints it. Otherwise, it prints error messages.

🧠 Conceptual

intermediate

Which Arduino pin is commonly used for CS (Chip Select) in SD card wiring?

When wiring an SD card module to an Arduino Uno, which pin is most commonly used for the CS (Chip Select) signal?

A Pin A0

B Pin 13

C Pin 10

D Pin 7

💡 Hint

Look for the default CS pin used in Arduino SD examples.

Pin 10 is the default Chip Select pin for SPI devices on Arduino Uno, including SD card modules.

🔧 Debug

advanced

Why does this SD card initialization code fail?

Look at this Arduino code snippet. It fails to initialize the SD card. What is the most likely cause?

Arduino

#include <SD.h>
const int chipSelect = 4;
void setup() {
  Serial.begin(9600);
  if (!SD.begin(chipSelect)) {
    Serial.println("Initialization failed!");
    return;
  }
  Serial.println("Initialization done.");
}
void loop() {}

A The loop function is empty

B The Serial baud rate is too low

C The SD library is not included properly

D Pin 4 is not the correct CS pin for the SD card wiring

💡 Hint

Check if the chipSelect pin matches the wiring.

If the SD card module's CS pin is wired to pin 10 but the code uses pin 4, initialization will fail.

📝 Syntax

advanced

What error does this SD card wiring code produce?

What error will this Arduino code produce when compiled?

Arduino

#include <SD.h>
const int chipSelect = 10;
void setup() {
  Serial.begin(9600);
  if (!SD.begin(chipSelect)) {
    Serial.println("Failed");
  }
}
void loop() {}

A SyntaxError: missing semicolon after 'const int chipSelect = 10'

B TypeError: SD.begin expects a boolean argument

C RuntimeError: SD card not found

D No error, code compiles and runs

💡 Hint

Look carefully at the line declaring chipSelect.

Missing semicolon after variable declaration causes a syntax error in Arduino C++.

🚀 Application

expert

How many SPI pins are used to wire an SD card module to Arduino Uno?

When wiring an SD card module to an Arduino Uno, how many SPI pins are connected (excluding power and ground)?

A 4 pins: MOSI, MISO, SCK, CS

B 3 pins: MOSI, MISO, SCK

C 2 pins: MOSI and MISO only

D 5 pins: MOSI, MISO, SCK, CS, and RESET

💡 Hint

Remember the SPI bus plus the chip select pin.

SPI communication uses MOSI, MISO, and SCK pins plus a CS pin to select the device.