1.4 FAT File System Using SDSPI Media

This application shows an example of using the MPLAB Harmony File System to access and modify the contents of a SD card using the SDSPI driver and the SPI PLIB.

Description

File System Operations on the SD Card

  • Application opens a file named FILE_TOO_LONG_NAME_EXAMPLE_123.JPG in the root directory of the SD card and reads its content into memory:
    • The image file could be any arbitrary JPEG (image) file chosen by the user and then renamed to FILE_TOO_LONG_NAME_EXAMPLE_123.JPG
  • Application creates directory named Dir1 in the root directory
  • Application creates a new file named FILE_TOO_LONG_NAME_EXAMPLE_123.JPG inside Dir1
  • Application copies the content from step 1 into this newly created file

The reason for choosing a JPEG file for test purposes is that the duplicate file, Dir1/FILE_TOO_LONG_NAME_EXAMPLE_123.JPG created by the demonstration could be easily verified for correctness. If the new file inside Dir1 opens for viewing on the computer and matches to original image, the test is deemed to have passed. Otherwise, if the file does not open (i.e., is corrupted), the test will be considered to have failed.

Note: Since the application creates a directory named Dir1, it is important that a folder with the same name does not exist on the SD card. If a directory named Dir1 is already present on the SD card, the application will fail.

File System Layer Uses

  • SDSPI Driver to communicate to SD card over SPI interface

Downloading and Building the Application

To clone or download this application from GitHub, go to the main page of this repository and then click Clone button to clone this repository or download as zip file. This content can also be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/fs/sdspi_fat/firmware.

To build the application, refer to the following table and open the project using its IDE.

Project NameDescription
pic32mm_usb_curiosity.XMPLAB X project for PIC32MM USB Curiosity Development Board

Setting Up the Hardware

The following table shows the target hardware for the application projects.

Project NameDescription
pic32mm_usb_curiosity.XPIC32MM USB Curiosity Development Board

Setting Up PIC32MM USB Curiosity Development Board

  • To run the demo, the following additional hardware is required:
    • microSD Click board
    • One microSD card
    • Create a new JPEG file in the SD card with name FILE_TOO_LONG_NAME_EXAMPLE_123.JPG
    • Insert the microSD card in the microSD card slot of the microSD Click board
  • Connect micro USB cable to the USB1 connector on the board to the computer
  • Install the microSD Click board onto the mikroBUS socket J12 of PIC32MM USB Curiosity Development Board
    Note: Ensure that the series resistors on the mikroBUS headers are of value 0Ω.

Running the Application

  1. Build and program the application using its IDE.
  2. Press Switch to start the file operations.
  3. The LED is turned ON if there was no error during creating the directory and copying the file into it.
    Refer to the following table for Switch and LED names:
    BoardSwitch NameLED Name
    PIC32MM USB Curiosity Development BoardS1LED1
  4. If LED is ON, insert the SD card into the host PC.
  5. SD card should have the file Dir1/FILE_TOO_LONG_NAME_EXAMPLE_123.JPG and should match the original image.