从SD卡读出一个字符，他怎么也算是一个字节？？？

hpdell 提问时间：2010-7-12 09:27 /

sd卡读出数据后，如何送入ILI9325的屏进行显示

                                 请教高手：我现在可以从SD卡中读出数据（抄袭的），但是从SD中读出一个字符他也会认为是一个字节的数据，请问这个要怎么改啊？不知道是不是这个读出一个字节的函数有问题还是？？？望高人指点！！
         我的QQ:519212866

         unsigned char bdata _dat;
         sbit _dat7 = _dat^7;
         sbit _dat6 = _dat^6;
         sbit _dat5 = _dat^5;
         sbit _dat4 = _dat^4;
         sbit _dat3 = _dat^3;
         sbit _dat2 = _dat^2;
         sbit _dat1 = _dat^1;
         sbit _dat0 = _dat^0;


         unsigned char SD_spi_read() //SPI读一个字节
         {
           SD_SO=1;
           SD_SCL=1;
           SD_SCL=0;
           _dat7=SD_SO;
           SD_SCL=1;
           SD_SCL=0;
           _dat6=SD_SO;
           SD_SCL=1;
           SD_SCL=0;
           _dat5=SD_SO;
           SD_SCL=1;
           SD_SCL=0;
           _dat4=SD_SO;
           SD_SCL=1;
           SD_SCL=0;
           _dat3=SD_SO;
           SD_SCL=1;
           SD_SCL=0;
           _dat2=SD_SO;
           SD_SCL=1;
           SD_SCL=0;
           _dat1=SD_SO;
           SD_SCL=1;
           SD_SCL=0;
           _dat0=SD_SO;

           return (_dat);
         }

         unsigned char SD_Read_Sector(unsigned long addr,unsigned char *buffer)//从SD卡的指定扇区中读出512个字节，使用CMD17（17号命令）
         {
           unsigned int j;
           unsigned char time,temp;
           unsigned char pcmd[]={0x51,0x00,0x00,0x00,0x00,0xff}; //CMD17的字节序列

           addr16)>>8);   //12T 0.13835ms
           pcmd[2] = (unsigned char)((unsigned int)(addr>>16));      //10T 0.00271ms
           pcmd[3] = (unsigned char)(((unsigned int)addr)>>8);       //7T 0.0038ms
           //pcmd[4] = (unsigned char)((unsigned int)addr);            //5T 0.00271ms

           SD_CS=0;//打开片选
           time=0;
           do
           {
            temp=SD_Write_Cmd(pcmd); //写入CMD17
            time++;
            if(time==TRY_TIME)
            {
             return(READ_BLOCK_ERROR); //读块失败
            }
           }while(temp!=0);

           while (SD_spi_read()!= 0xfe); //一直读，当读到0xfe时，说明后面的是512字节的数据了
           for(j=0;jpfi->FileSize) len=pfi->FileSize-offset;
            znFAT_Seek_File(pfi,offset);

            znFAT_ReadSector(pfi->FileCurSector,znFAT_Buffer);
            for(i=pfi->FileCurPos;iBytesPerSector;i++)
            {
             if(counter>=len)
             {
               return len;
             }
             (*pfun)(znFAT_Buffer);
             counter++;
             pfi->FileCurPos++;
             pfi->FileCurOffset++;
            }
            if(pfi->FileCurSector-(SOC(pfi->FileCurCluster))!=(pArg->SectorsPerClust-1))
            {
             for(j=pfi->FileCurSector+1;jFileCurCluster))+pArg->SectorsPerClust;j++)
             {
              znFAT_ReadSector(j,znFAT_Buffer);
              pfi->FileCurSector=j;
              for(i=0;iBytesPerSector;i++)
              {
               if(counter>=len)
               {
                 return len;
               }
               (*pfun)(znFAT_Buffer);
               counter++;
               pfi->FileCurPos++;
               pfi->FileCurOffset++;
              }
             }
            }
            temp=(len-counter)/(pArg->BytesPerSector*pArg->SectorsPerClust);
            for(k=0;kFileCurCluster=znFAT_GetNextCluster(pfi->FileCurCluster);
             for(j=(SOC(pfi->FileCurCluster));jFileCurCluster))+pArg->SectorsPerClust;j++)
             {
              znFAT_ReadSector(j,znFAT_Buffer);
              pfi->FileCurSector=j;
              for(i=0;iBytesPerSector;i++)
              {
               if(counter>=len)
             {
                 return len;
               }
               (*pfun)(znFAT_Buffer);
               counter++;
               pfi->FileCurOffset++;
            pfi->FileCurPos++;
            pfi->FileCurPos%=pArg->BytesPerSector;
              }
             }
            }
            pfi->FileCurCluster=znFAT_GetNextCluster(pfi->FileCurCluster);
            temp=(SOC(pfi->FileCurCluster))+((len-counter)/pArg->BytesPerSector);
            pfi->FileCurSector=(SOC(pfi->FileCurCluster));
            for(j=(SOC(pfi->FileCurCluster));jFileCurSector=j;
             for(i=0;iBytesPerSector;i++)
             {
              if(counter>=len)
              {
                return len;
              }
              (*pfun)(znFAT_Buffer);
              counter++;
              pfi->FileCurPos++;
              pfi->FileCurPos%=pArg->BytesPerSector;
              pfi->FileCurOffset++;
             }
            }
            pfi->FileCurSector=j;
            znFAT_ReadSector(pfi->FileCurSector,znFAT_Buffer);
            temp=len-counter;
            for(i=0;i=len)
             {
               return len;
             }
             (*pfun)(znFAT_Buffer);
             counter++;
             pfi->FileCurPos++;
             pfi->FileCurPos%=pArg->BytesPerSector;
             pfi->FileCurOffset++;
            }
           }
           else
           {
            len=0;
           }
           return len;
         }