STM32库开发实战指南关于用I2C操作24C02的bug

只看该作者 · 2020-4-25 13:54

函数I2C_EE_BufferWrite中，对于需要写入的起始地址与整数页数是否对齐进行了判断，并且对写入的数据总数是否满足整数页数进行了判断。在处理写入地址非对齐模式的时候有bug。见如下代码：void I2C_EE_BufferWrite(u8* pBuffer, u8 WriteAddr, u16 NumByteToWrite)
{
  u8 NumOfPage = 0, NumOfSingle = 0, Addr = 0, count = 0;

  Addr = WriteAddr % I2C_PageSize;
  count = I2C_PageSize - Addr;
  NumOfPage =  NumByteToWrite / I2C_PageSize;
  NumOfSingle = NumByteToWrite % I2C_PageSize;

  /* If WriteAddr is I2C_PageSize aligned  */
  if(Addr == 0)
  {
/* If NumByteToWrite < I2C_PageSize */
if(NumOfPage == 0)
{
   I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
   I2C_EE_WaitEepromStandbyState();
}
/* If NumByteToWrite > I2C_PageSize */
else
{
   while(NumOfPage--)
   {
      I2C_EE_PageWrite(pBuffer, WriteAddr, I2C_PageSize);
                              I2C_EE_WaitEepromStandbyState();
      WriteAddr +=  I2C_PageSize;
      pBuffer += I2C_PageSize;
   }

   if(NumOfSingle!=0)
   {
      I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
      I2C_EE_WaitEepromStandbyState();
   }
}
  }
  /* If WriteAddr is not I2C_PageSize aligned  */
  else
  {
/* If NumByteToWrite < I2C_PageSize */
if(NumOfPage== 0) //这里没有考虑到写入的地址不是跟I2C_PageSize对齐，并且写入的数量超过一页的情况。
{
   I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
   I2C_EE_WaitEepromStandbyState();
}
/* If NumByteToWrite > I2C_PageSize */
else
{
   NumByteToWrite -= count;
   NumOfPage =  NumByteToWrite / I2C_PageSize;
   NumOfSingle = NumByteToWrite % I2C_PageSize;

   if(count != 0)
   {
      I2C_EE_PageWrite(pBuffer, WriteAddr, count);
      I2C_EE_WaitEepromStandbyState();
      WriteAddr += count;
      pBuffer += count;
   }

   while(NumOfPage--)
   {
      I2C_EE_PageWrite(pBuffer, WriteAddr, I2C_PageSize);
      I2C_EE_WaitEepromStandbyState();
      WriteAddr +=  I2C_PageSize;
      pBuffer += I2C_PageSize;
   }
   if(NumOfSingle != 0)
   {
      I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
      I2C_EE_WaitEepromStandbyState();
   }
}
  }
}

上述代码中没有考虑到不对齐的时候，如果写入的数据超过当前页剩余的部分，就会出现这小部分覆盖了前面的数据的情况。比如从0x03开始写入7个字节，当前分页剩余只有5个字节，写入7个会依次写入到0x03,0x04,0x05,0x06,0x07,0x00,0x01覆盖0x00,0x01这两个字节。此处应该对当前页剩余的字节数进行一个判断。

STM32库开发实战指南关于用I2C操作24C02的bug

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