Petr Listerman

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10 years, 6 months ago.

SD Card on FRDM KL25Z

How use SD Card on FRDM KL25Z

Question relating to:

Last updated: 30 Apr 2020
Freedom, Freescale, KL25z

2 Answers

jesus Patiño
10 years, 1 month ago.

Does this library has read methods too?

Yes, you can read from files on the SD card using standard functions. Example:

Reading from a file on the SD card

     printf("Reading from SD card...");
     fp = fopen("/sd/mydir/test.txt", "r");
     if (fp != NULL) {
         char c = fgetc(fp);
         if (c == 'H')
             printf("success!\n");
         else
             printf("incorrect char (%c)!\n", c);
         fclose(fp);
     } else {
         printf("failed!\n");
     }
posted by Frank Agius 12 Oct 2015
Frank Agius
10 years, 4 months ago.

First you attach an SD breakout board, such as this one from sparkfun: https://www.sparkfun.com/products/544 Or if you have a spare SD card adapter and are handy with a soldering iron, you can make your own: http://www.bot-thoughts.com/2010/02/logging-data-to-sd-cards.html

Here's the code that should be able to write to a FAT formatted SD card. I used the SD FileSystem library from here: https://developer.mbed.org/users/neilt6/code/SDFileSystem/

kl25z example interfacing to an SD card. Include the SDFileSystem library with this code


include "mbed.h"
#include "SDFileSystem.h"

 // sd card breakout board: https://www.sparkfun.com/products/544
 //
 // frdm-kl25z sd card connections spi0
 // ------------------------------------------------
 // Header -- kl25z -- SPI          
 // J2-8   -- PTD2  -- MOSI
 // J2-6   -- PTD0  -- CS
 // J9-12  -- GND   -- Vss (GND) 
 // J9-4   -- P3V3  -- Vdd (+3.3v)
 // J2-12  -- PTD1  -- SCK
 // J9-14  -- GND   -- Vss (GND)
 // J2-10  -- PTD3  -- MISO
  
SDFileSystem sd(PTD2, PTD3, PTD1, PTD0, "sd"); //  mosi, miso, sck, cs
Serial pc(USBTX,USBRX);

int main() {

    printf("start sd card test!\r\n");
    mkdir("/sd/mydir", 0777);
    FILE *fp = fopen("/sd/mydir/test.txt", "w");
    if(fp == NULL) {
        error("Could not open file for write\r\n");
    }
    else
        printf("file opened for writing\r\n");
        
    fprintf(fp, "Hello fun SD Card World!");
    fclose(fp); 
    printf("completed sd card test!\r\n");
}