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外部扩展 RAM 访问方式

已有 445 次阅读2013-10-27 22:05

请问以下两种方式读取外部扩展RAM，有什么差别呢？为什么在我的程序返回的结果很怪呢？
方式一：
   j = 0x0016;
   k = 0x16;
   pToV = &pV->bTsAddr;//0x4016
   for( i = 0x16; i < RAM_LENGTH; i++ )
   {
      *pToV=k;

      abSndBuffer [bWriteSndPtr++] = 0x5A; bSndCounter++;\\
      abSndBuffer [bWriteSndPtr++] = (uint8_t)(i>>8); bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)i; bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = 0x5A; bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)k; bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = 0x5A; bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)*pToV; bSndCounter++;
      StartSerialCommunication();
      pToV++;
      j++;k++;
   }

串口接收如下结果：
5A 00 16 5A 16 5A 16
5A 00 17 5A 17 5A 17
5A 00 18 5A 18 5A 18
5A 00 19 5A 19 5A 19
5A 00 1A 5A 1A 5A 1A
5A 00 1B 5A 1B 5A 1B
5A 00 1C 5A 1C 5A 1C
5A 00 1D 5A 1D 5A 1D
5A 00 1E 5A 1E 5A 1E
5A 00 1F 5A 1F 5A 1F
5A 00 20 5A 20 5A 20
. . .

方式二：
   j = 0x0016;
   pToV = &pV->bTsAddr;
   for( i = 0x16; i < RAM_LENGTH; )
   {
      *pToV = (uint8_t)(j>>8);
      pToV++;
      *pToV = (uint8_t)j;
      pToV++;

      abSndBuffer [bWriteSndPtr++] = 0x5A; bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)(i>>8); bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)i; bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)(j>>8); bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)j; bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)(*(pToV-2)); bSndCounter++;
      abSndBuffer [bWriteSndPtr++] = (uint8_t)(*(pToV-1)); bSndCounter++;
      StartSerialCommunication();

      i+=2;
      j+=2;
   }

串口接收如下结果：
5A 00 16 00 16 16 17
5A 00 18 00 18 18 19
5A 00 1A 00 1A 1A 1B
5A 00 1C 00 1C 1C 1D
5A 00 1E 00 1E 1E 1F
5A 00 20 00 20 20 21
. . .

各位帮忙看看吧，实在找不出问题在哪里

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