F2812mcbsp用作SPI和ADS1271通信怎么设置？

请教各位专家、大侠：
        我用F2812mcbsp用作SPI和ADS1271通信，只用到CLKX和DR管脚，但初始化后，在读取数据时，CLKX无时钟产生，一直保持高电平，初始化设置如下：
void InitMcbsp(void)
[
EALLOW;
GpioMuxRegs.GPFMUX.bit.MCLKXA_GPIOF8=1;
GpioMuxRegs.GPFMUX.bit.MDRA_GPIOF13=1;
GpioMuxRegs.GPFMUX.bit.MDXA_GPIOF12=1;
GpioMuxRegs.GPFMUX.bit.MFSXA_GPIOF10=1;
EDIS;
  
McbspRegs.SPCR2.bit.XRST = 0;
McbspRegs.SPCR1.bit.RRST = 0;
  McbspRegs.SPCR2.bit.GRST = 0;
  
  //Mcbsp配置成SPI主设备
  
McbspRegs.SPCR1.bit.CLKSTP = 1;
McbspRegs.PCR1.bit.CLKXP = 1;
// McbspRegs.PCR1.bit.CLKRP = 1;
McbspRegs.PCR1.bit.CLKXM = 1;
McbspRegs.PCR1.bit.SCLKME = 0;
McbspRegs.SRGR2.bit.CLKSM= 1;
McbspRegs.SRGR1.bit.CLKGDV = 0xaa;

McbspRegs.PCR1.bit.FSXM = 1;
McbspRegs.SRGR2.bit.FSGM = 0;
McbspRegs.PCR1.bit.FSXP=1;
McbspRegs.XCR2.bit.XDATDLY = 1;
McbspRegs.RCR2.bit.RDATDLY = 1;

McbspRegs.SPCR1.bit.DXENA=1;


McbspRegs.RCR1.bit.RWDLEN1 = 1;
McbspRegs.XCR1.bit.XWDLEN1 = 1;
  
McbspRegs.PCR1.bit.FSRM = 1;
   //使能
NOP;
NOP;

McbspRegs.SPCR2.bit.GRST = 1;
NOP;
NOP;
  McbspRegs.SPCR2.bit.XRST = 1;
  McbspRegs.SPCR1.bit.RRST = 1;
NOP;
NOP;
// PieCtrl.PIEIER6.bit.INTx5 = 1;
// PieCtrl.PIEIER6.bit.INTx6 = 1;
]
在读程序中，我已经写了，先发数据，产生时钟，再读数据， SysCtrlRegs.PCLKCR.bit.MCBSPENCLK =1也已经设置。
请帮忙指教，设置有什么问题？谢谢了！