请问VC5502 MCBSP配置为SPI接口后发送数据的最后2位只要是以二进制10结尾（2，6，a, e）的数据均会变成11是为什么？

问题如标题所述，我需要和CH374U通讯，ch374u读写时序是每次3个字节分别是ADDRESS + READ_CMD + xxxx，ADRESS + WRITE_CMD + WRITE_DATA，我配置mcbsp为spi， 单相，单帧，每帧24位。
一下是我的mcbsp的配置：
#define CFG_MCBSP_AS_SPI
[
MCBSP_SPCR1_RMK(
MCBSP_SPCR1_DLB_OFF,
MCBSP_SPCR1_RJUST_RZF,
MCBSP_SPCR1_CLKSTP_NODELAY,
MCBSP_SPCR1_DXENA_OFF,
MCBSP_SPCR1_ABIS_DISABLE,
MCBSP_SPCR1_RINTM_RRDY,
MCBSP_SPCR1_RSYNCERR_NO,
MCBSP_SPCR1_RRST_DISABLE
),
MCBSP_SPCR2_RMK(
MCBSP_SPCR2_FREE_YES,
MCBSP_SPCR2_SOFT_YES,
MCBSP_SPCR2_FRST_RESET,
MCBSP_SPCR2_GRST_RESET,
MCBSP_SPCR2_XINTM_XRDY,
MCBSP_SPCR2_XSYNCERR_NO,
MCBSP_SPCR2_XRST_DISABLE
),
MCBSP_RCR1_RMK(
MCBSP_RCR1_RFRLEN1_OF(0),
MCBSP_RCR1_RWDLEN1_24BIT
),
MCBSP_RCR2_RMK(
MCBSP_RCR2_RPHASE_SINGLE,
MCBSP_RCR2_RFRLEN2_OF(0),
MCBSP_RCR2_RWDLEN2_8BIT,
MCBSP_RCR2_RCOMPAND_MSB,
MCBSP_RCR2_RFIG_YES,
MCBSP_RCR2_RDATDLY_1BIT
),
MCBSP_XCR1_RMK(
MCBSP_XCR1_XFRLEN1_OF(0),
MCBSP_XCR1_XWDLEN1_24BIT
),
MCBSP_XCR2_RMK(
MCBSP_XCR2_XPHASE_SINGLE,
MCBSP_XCR2_XFRLEN2_OF(0),
MCBSP_XCR2_XWDLEN2_8BIT,
MCBSP_XCR2_XCOMPAND_MSB,
MCBSP_XCR2_XFIG_YES,
MCBSP_XCR2_XDATDLY_1BIT
),
MCBSP_SRGR1_RMK(
MCBSP_SRGR1_FWID_OF(2),
MCBSP_SRGR1_CLKGDV_OF(9)
),
MCBSP_SRGR2_RMK(
MCBSP_SRGR2_GSYNC_FREE,
MCBSP_SRGR2_CLKSP_RISING,
MCBSP_SRGR2_CLKSM_INTERNAL,
MCBSP_SRGR2_FSGM_DXR2XSR,
MCBSP_SRGR2_FPER_OF(26)
),
MCBSP_MCR1_DEFAULT,
MCBSP_MCR2_DEFAULT,
MCBSP_PCR_RMK(
MCBSP_PCR_XIOEN_SP,
MCBSP_PCR_RIOEN_SP,
MCBSP_PCR_FSXM_INTERNAL,
MCBSP_PCR_FSRM_INTERNAL,
MCBSP_PCR_CLKXM_OUTPUT,
MCBSP_PCR_CLKRM_OUTPUT,
MCBSP_PCR_SCLKME_NO,
MCBSP_PCR_DXSTAT_0,
MCBSP_PCR_FSXP_ACtiVELOW,
MCBSP_PCR_FSRP_ACTIVELOW,
MCBSP_PCR_CLKXP_RISING,
MCBSP_PCR_CLKRP_FALLING
),
MCBSP_RCERA_DEFAULT,
MCBSP_RCERB_DEFAULT,
MCBSP_RCERC_DEFAULT,
MCBSP_RCERD_DEFAULT,
MCBSP_RCERE_DEFAULT,
MCBSP_RCERF_DEFAULT,
MCBSP_RCERG_DEFAULT,
MCBSP_RCERH_DEFAULT,
MCBSP_XCERA_DEFAULT,
MCBSP_XCERB_DEFAULT,
MCBSP_XCERC_DEFAULT,
MCBSP_XCERD_DEFAULT,
MCBSP_XCERE_DEFAULT,
MCBSP_XCERF_DEFAULT,
MCBSP_XCERG_DEFAULT,
MCBSP_XCERH_DEFAULT
]
以下是我的读写函数：
UINT32 spi_read(void)
[
while(!MCBSP_rrdy(mcbsp_handle))
;
return MCBSP_read32(mcbsp_handle);
]
void spi_write(const UINT32 data)
[
while(!MCBSP_xrdy(mcbsp_handle))
;
MCBSP_write32(mcbsp_handle, data);
]
调试图如下：