File content as of revision 0:09c855ba2df2:

// SDFileSystem---1. https://developer.mbed.org/users/mbed_official/code/SDFileSystem/
//                2. https://developer.mbed.org/users/simon/code/SDCardTest/
// VCC:3.3v
#include "mbed.h"
#include "SDFileSystem.h"
 
//SDFileSystem sd(PA_7, PA_6, PA_5, PB_6, "sd"); //  mosi, miso, sclk, cs
//SPI spi(SPI_MOSI, SPI_MISO, SPI_SCK);
//SPI_MOSI = PA_7, SPI_MISO = PA_6, SPI_SCK = PA_5, SPI_CS = PB_6,
SDFileSystem sd( D4, D5, D3, D6, "sd"); //  mosi, miso, sclk, cs

int main() 
{
    printf("Hello World!\n");   
    
    mkdir("/sd/Amber", 0777);  //SD裡面的資料夾叫Amber,在此做宣告
    FILE *fp = fopen("/sd/Amber/Amber77.txt", "w");       //將檔案存進SD的資料夾Amber裡面,並取名為Amber77.txt
 
    /*mkdir("/sd/mydir", 0777);  //SD裡面的資料夾叫mydir,在此做宣告
    FILE *fp = fopen("/sd/mydir/Amber77.txt", "w");*/       //將檔案存進SD的資料夾mydir裡面,並取名為sdtest.txt
    
    /*
    mkdir("/sd/Amber20170222", 0777);  //SD裡面的資料夾叫Amber77,在此做宣告
    FILE *fp = fopen("/sd/Amber20170222/AngVel_PWM20170222a.csv", "a");     
    //將檔案存進SD的資料夾Amber77裡面,並取名為PWM_AngVel_PWM.xls/.xlsx/.csv
    fprintf(fp,"RunTime,Now_angularVelocity,control_PWM_Value\n");
    
    if(fp == NULL) 
            {
                    error("Could not open file for write\n");
            }
            fprintf(fp,"%.3f,%.3f,%.3f\n", RunTime,Now_angularVelocity,control_PWM_Value);  
            
    if(!mybutton)
        {
            StopRun.write(1);
            CW_CCW.write(1);                   // clockwise:0    counterclockwise:1
            PWM.write(0);
            break;
        }
    }
    fclose(fp);
    
    */
    
    
    if(fp == NULL) 
    {
        error("Could not open file for write\n");
    }
    fprintf(fp, "Go to the file ");             //檔案如sdtest.txt裡面的資料內容
    fclose(fp); 
 
    printf("Goodbye World!\n");
}