TMS320F2812无法进入串口接收中断的问题

我的问题是这样的：

在串口中断服务程序中函数A，能正常进接收中断。但调用函数B则不能进接收中断。

我的上位机系统中共开启了三个中断：一个10ms定时器中断CPU TIMER0，一个250us定时器中断CPU TIMER2以及SCIB接收中断。

CPU TIMER0中断通过SCIB发送请求命令道下位机，下位机返回数据。通过示波器测量上位机SCIB的RX引脚能观测到数据(无论是调用函数A，还是调用函数B)。

SCIBRx ISR：

	  // Insert ISR Code here
		char i = 0;
		unsigned short tmp = 0;
	

		if(ScibRegs.SCIRXST.bit.RXERROR)
		{
			ScibRegs.SCICTL1.bit.SWRESET = 0;

			asm(" NOP");
			asm(" NOP");
			asm(" NOP");

			ScibRegs.SCICTL1.bit.SWRESET = 1;
		}
		else
		{
			g_SCIBRxBuf.m_timeCnt = 0;

			i = ScibRegs.SCIFFRX.bit.RXFIFST;
			for(;i > 0;i--)
			{
                           ReceivMsgA();
                             
			}
			ScibRegs.SCIFFRX.bit.RXFFINTCLR = 1;  // Clear flag.
                        PieCtrlRegs.PIEACK.all = PIEACK_GROUP9;
		}

串口初始化函数

void initSCI(volatile struct SCI_REGS *sci,unsigned long baud)
{
	unsigned short brr;

	sci->SCICCR.all = 0x07;//One stop bit,No parity check,8 bits in every charactor.
	sci->SCICTL1.all = 0x43;//Enable TX,RX;Enable Rx error interruption.
	sci->SCICTL2.all = 0x02;//Enable Rx interruption and disable Tx interruption

	brr = ((SCI_IN_CLK + (baud << 2))/ (baud << 3)) - 1;//brr = LSPCLK / (baud * 8) - 1;
	sci->SCILBAUD = (unsigned char)brr;
	sci->SCIHBAUD = (unsigned char)(brr >> 8);
	sci->SCIFFTX.all = 0x401F; //Reset SCI,Reset Tx FIFO
	sci->SCIFFRX.all = 0x0000;
	sci->SCIFFCT.all = 0;
	sci->SCIPRI.all = 0x10;

	sci->SCIFFTX.all = 0xE01F;
	sci->SCIFFRX.all = 0x2021;//Resume RX FIFO,Enable Rx FIFO interruption,Whenever there is more than 1 bytes,
	                                  //a interruption is generated.
	sci->SCICTL1.all = 0x63;  //Enable

	if(sci == &SciaRegs)
	{
		EALLOW;
		GpioMuxRegs.GPFMUX.bit.SCIRXDA_GPIOF5 = 1;
		GpioMuxRegs.GPFMUX.bit.SCITXDA_GPIOF4 = 1;
		EDIS;

		PieCtrlRegs.PIEIER9.bit.INTx1 = 1;
	}
	else if(sci == &ScibRegs)
	{
		EALLOW;
		GpioMuxRegs.GPGMUX.bit.SCIRXDB_GPIOG5 = 1;
		GpioMuxRegs.GPGMUX.bit.SCITXDB_GPIOG4 = 1;
		EDIS;

		PieCtrlRegs.PIEIER9.bit.INTx3 = 1;
	}
	IER |= M_INT9;
}

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