透過I2C介面通信TI BQ32002 ，前置I2C LoopBack通信調試疑問 ?

void InitI2CGpio()
{

   EALLOW;

/* Enable internal pull-up for the selected pins */
// Pull-ups can be enabled or disabled disabled by the user.
// This will enable the pullups for the specified pins.
// Comment out other unwanted lines.

//	GpioCtrlRegs.GPAPUD.bit.GPIO28 = 0;    // Enable pull-up for GPIO28 (SDAA)
//	GpioCtrlRegs.GPAPUD.bit.GPIO29 = 0;	   // Enable pull-up for GPIO29 (SCLA)

	GpioCtrlRegs.GPBPUD.bit.GPIO32 = 0;    // Enable pull-up for GPIO32 (SDAA)
	GpioCtrlRegs.GPBPUD.bit.GPIO33 = 0;	   // Enable pull-up for GPIO33 (SCLA)

/* Set qualification for selected pins to asynch only */
// This will select asynch (no qualification) for the selected pins.
// Comment out other unwanted lines.

//    GpioCtrlRegs.GPAQSEL2.bit.GPIO28 = 3;  // Asynch input GPIO28 (SDAA)
//    GpioCtrlRegs.GPAQSEL2.bit.GPIO29 = 3;  // Asynch input GPIO29 (SCLA)

	GpioCtrlRegs.GPBQSEL1.bit.GPIO32 = 3;  // Asynch input GPIO32 (SDAA)
    GpioCtrlRegs.GPBQSEL1.bit.GPIO33 = 3;  // Asynch input GPIO33 (SCLA)

/* Configure I2C pins using GPIO regs*/
// This specifies which of the possible GPIO pins will be I2C functional pins.
// Comment out other unwanted lines.

//	GpioCtrlRegs.GPAMUX2.bit.GPIO28 = 2;   // Configure GPIO28 for SDAA operation
//	GpioCtrlRegs.GPAMUX2.bit.GPIO29 = 2;   // Configure GPIO29 for SCLA operation

	GpioCtrlRegs.GPBMUX1.bit.GPIO32 = 1;   // Configure GPIO32 for SDAA operation
	GpioCtrlRegs.GPBMUX1.bit.GPIO33 = 1;   // Configure GPIO33 for SCLA operation

    EDIS;
}


void i2c_init(void){

/************I2C LOOPBACK INIT****************/
    EALLOW;

    SysCtrlRegs.PCLKCR0.bit.I2CAENCLK = 1;

    I2caRegs.I2COAR=0x003F;  //7-bit addressing

    I2caRegs.I2CMDR.bit.IRS = 0;
    I2caRegs.I2CMDR.bit.DLB=1;

    I2caRegs.I2CPSC.all = 5;   //  7M <= 60M/(PSC+1)  <=12M
    I2caRegs.I2CCLKL = 7;
    I2caRegs.I2CCLKH = 8;
    I2caRegs.I2CMDR.bit.IRS = 1;

    EDIS;
/************I2C LOOPBACK INIT***************END*/

}


void I2C_WriteData(unsigned char data)
{
    I2caRegs.I2CSAR = 0x003F;
    I2caRegs.I2CMDR.bit.MST = 1;
    I2caRegs.I2CMDR.bit.TRX = 1;
    I2caRegs.I2CMDR.bit.STT = 1;
    I2caRegs.I2CMDR.bit.STP = 1;

    while(I2caRegs.I2CSTR.bit.BB!=1);
    I2caRegs.I2CDXR = data;
}

unsigned char I2C_ReadData()
{
    unsigned char data;
    I2caRegs.I2CMDR.bit.TRX = 0;
    I2caRegs.I2CMDR.bit.STT = 1;
    I2caRegs.I2CMDR.bit.STP = 1;
    while(I2caRegs.I2CSTR.bit.RRDY!=1);
    data = I2caRegs.I2CDRR&0x00ff;
    return data;
}

void main(void) {//�D�{��


	Hardware();		//�w���l��
	firmware();		//�����l��
	DELAY_US(20000);


	while(1){

    switch(TestCounter){
        case 1:   {
            I2C_WriteData('A');
            testdata=I2C_ReadData();
            TestCounter=0;
            break;
             }
        case 2: {
            I2C_WriteData('5');
            testdata=I2C_ReadData();
            TestCounter=0;
            break;
            }
        }
	}