利用fatfs文件系统实现了SD卡追加…

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原帖地址:http://www.amobbs.com/thread-5537678-1-1.html
在fatfs文件系统下,实现SD卡的读取追加内容,实现方法是:读取文件、偏移指针、填写内容。追加内容时需要利用f_sleek函数将指针移到文本尾部,再写问容,具体实现main函数的功能是两个按键来控制添加不同的内容,按键1按下时添加 BYTE sample_buffer[] ="2710,2712,2711,2715,1234,2134,4567,7890 \r\n";按键2按下时添加 BYTEsample_buffer1[] = "1,2,3,4,5,6,7,8,9,0 \r\n";
printf 调试用,
问题是:保存到txt文件中的数据不规则,应该是每一行数据都是靠左边对齐才对,实际是如附件图片所示。


程序:

while (1)
   
      if( Key_Scan(GPIOE,GPIO_Pin_5) ==KEY_ON)//按键1按下时添加sample_buffer中内容
      {
          printf("\r\n KEY1 PE5  \n");//串口输出调试信息
          
          res =f_open(&fdst,"0:/Demo.TXT", FA_WRITE);//打开文本,while之前已经      f_mount(0,&fs);

         if( res ==FR_OK)
         {
          printf("\r\n SD has opened  \n" );
          
               res =f_lseek(&fdst, f_size(&fdst));  
              res = f_write(&fdst,sample_buffer, sizeof(sample_buffer), &bw);
              f_close(&fdst);
           printf("\r\n sample_buffer \n" );
         }
      }
         if(Key_Scan(GPIOE,GPIO_Pin_6) == KEY_ON) //按键2按下时添加 sample_buffer1中内容
      {
          printf("\r\n KEY2 PE6  \n" );
           
          res =f_open(&fdst,"0:/Demo.TXT", FA_WRITE);

         if( res ==FR_OK)
         {
           printf("\r\n SD has opened  \n" );
          
               res =f_lseek(&fdst, f_size(&fdst));  
              res = f_write(&fdst,sample_buffer1, sizeof(sample_buffer), &bw);
              f_close(&fdst);
           printf("\r\n sample_buffer1 \n" );
         }
      }       
  }

试验结果:txt文本内容
实际显示内容对齐方式是:

感谢您选用 野火STM32开发板 !^_^
1,2,3,4,5,6,7,8,9,0
               1,2,3,4,5,6,7,8,9,0
               1,2,3,4,5,6,7,8,9,0
               1,2,3,4,5,6,7,8,9,0
               1,2,3,4,5,6,7,8,9,0
               2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
1,2,3,4,5,6,7,8,9,0
               1,2,3,4,5,6,7,8,9,0
               1,2,3,4,5,6,7,8,9,0

理论或是理想中的显示内容对齐方式是:

感谢您选用 野火STM32开发板 !^_^
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
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