i2c EEPROM STP

我在进行完写操作后，STP置1了后，为何不能自动清零，还保持为1啊

I2caRegs.I2CMDR.all = 0x6E20;-//----当运行完这一步后，I2caRegs.I2CMDR.bit.STP应该是自动清零，我在程序中为何没有自动清零啊，            2caRegs.I2CMDR.bit.STP 保持为1

Uint16 I2CA_WriteData(struct I2CMSG *msg)
{
   Uint16 i;

   // Wait until the STP bit is cleared from any previous master communication.
   // Clearing of this bit by the module is delayed until after the SCD bit is
   // set. If this bit is not checked prior to initiating a new message, the
   // I2C could get confused.
   if (I2caRegs.I2CMDR.bit.STP == 1)
   {
      return I2C_STP_NOT_READY_ERROR;
   }

   // Setup slave address
   I2caRegs.I2CSAR = msg->SlaveAddress;

   // Check if bus busy
   if (I2caRegs.I2CSTR.bit.BB == 1)
   {
      return I2C_BUS_BUSY_ERROR;
   }

   // Setup number of bytes to send
   // MsgBuffer + Address
   I2caRegs.I2CCNT = msg->NumOfBytes+2;

   // Setup data to send
   I2caRegs.I2CDXR = msg->MemoryHighAddr;
   I2caRegs.I2CDXR = msg->MemoryLowAddr;
// for (i=0; i<msg->NumOfBytes-2; i++)
   for (i=0; i<msg->NumOfBytes; i++)

   {
      I2caRegs.I2CDXR = *(msg->MsgBuffer+i);
   }

   // Send start as master transmitter
   I2caRegs.I2CMDR.all = 0x6E20;-//----当运行完这一步后，I2caRegs.I2CMDR.bit.STP应该是自动清零，我在程序中为何没有自动清零啊，                //////////I2caRegs.I2CMDR.bit.STP == 1

   return I2C_SUCCESS;
}