How to Use SD Memory Card HW-125: Examples, Pinouts, and Specs

The SD Memory Card HW-125 is a secure digital (SD) memory card module designed for use in electronic devices requiring compact, high-capacity data storage. It is commonly used in applications such as data logging, multimedia storage, and file transfer. The HW-125 module provides an interface for connecting an SD card to microcontrollers or other host devices, making it ideal for projects involving Arduino, Raspberry Pi, or other embedded systems.

• Data logging in IoT devices (e.g., temperature, humidity, or GPS data)
• Multimedia storage for photos, videos, and audio files
• File transfer between microcontrollers and computers
• Storing configuration files or firmware updates
• Projects requiring removable storage solutions

The SD Memory Card HW-125 module is designed to interface with standard SD cards and microcontrollers. Below are the key technical details:

• Operating Voltage: 3.3V (logic level) or 5V (via onboard voltage regulator)
• Communication Protocol: SPI (Serial Peripheral Interface)
• Supported SD Card Types: Standard SD and microSD (with adapter)
• Maximum Storage Capacity: Dependent on the SD card used (up to 32GB for FAT32)
• Dimensions: 42mm x 24mm x 12mm (approx.)

The HW-125 module has a 6-pin interface for connecting to a microcontroller. The table below describes each pin:

1. Power the Module: Connect the VCC pin to a 3.3V or 5V power source and the GND pin to ground.
2. Connect SPI Pins: Connect the MISO, MOSI, SCK, and CS pins to the corresponding SPI pins on your microcontroller.
3. Insert an SD Card: Ensure the SD card is formatted to FAT16 or FAT32 before inserting it into the module.
4. Initialize the SD Card: Use an appropriate library (e.g., the Arduino SD library) to initialize and communicate with the SD card.

• Voltage Compatibility: The HW-125 module includes a voltage regulator, allowing it to work with 5V systems. However, ensure your microcontroller's SPI pins are compatible with 3.3V logic levels.
• SD Card Formatting: Format the SD card to FAT16 or FAT32 for compatibility with most libraries.
• Pull-Up Resistors: Some microcontrollers may require pull-up resistors on the SPI lines for stable communication.
• Avoid Hot-Swapping: Do not insert or remove the SD card while the module is powered to prevent data corruption.

Below is an example of how to use the HW-125 module with an Arduino UNO to read and write data to an SD card:

#include <SPI.h>
#include <SD.h>

// Define the Chip Select (CS) pin for the SD card module
const int chipSelect = 10;

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);
  while (!Serial) {
    ; // Wait for the serial port to connect (for native USB boards)
  }

  Serial.println("Initializing SD card...");

  // Initialize the SD card
  if (!SD.begin(chipSelect)) {
    Serial.println("SD card initialization failed!");
    return; // Stop the program if initialization fails
  }
  Serial.println("SD card initialized successfully.");

  // Create or open a file on the SD card
  File dataFile = SD.open("example.txt", FILE_WRITE);

  // Check if the file opened successfully
  if (dataFile) {
    dataFile.println("Hello, SD card!"); // Write data to the file
    dataFile.close(); // Close the file
    Serial.println("Data written to example.txt.");
  } else {
    Serial.println("Error opening example.txt for writing.");
  }
}

void loop() {
  // Nothing to do here
}

1. SD Card Initialization Fails

   • Cause: Incorrect wiring or incompatible SD card format.
   • Solution: Double-check the wiring and ensure the SD card is formatted to FAT16 or FAT32.

2. Data Corruption

   • Cause: Removing the SD card while the module is powered.
   • Solution: Always power down the module before removing the SD card.

3. File Not Found or Cannot Open

   • Cause: Incorrect file path or file permissions.
   • Solution: Verify the file path and ensure the file exists on the SD card.

4. Unstable Communication

   • Cause: Missing pull-up resistors or noisy power supply.
   • Solution: Add pull-up resistors to the SPI lines and use a stable power source.

• Q: Can I use a microSD card with the HW-125 module?
  A: Yes, you can use a microSD card with an appropriate adapter.

• Q: What is the maximum storage capacity supported?
  A: The module supports SD cards up to 32GB formatted in FAT32.

• Q: Can I use the HW-125 with a 3.3V microcontroller?
  A: Yes, the module is compatible with 3.3V logic levels.

• Q: Do I need additional libraries to use the module with Arduino?
  A: The Arduino SD library is sufficient for most applications. Install it via the Arduino IDE Library Manager if not already available.