spi 选用如下io口，写数据的时候，通过示波器可以看出CLK正确，但是SI SO两个引脚保持高电平或者低电平不变。
GpioCtrlRegs.GPBPUD.bit.GPIO54 = 0; // Enable pull-up on GPIO16 (SPISIMOA)
GpioCtrlRegs.GPBPUD.bit.GPIO55 = 0; // Enable pull-up on GPIO17 (SPISOMIA)
GpioCtrlRegs.GPBPUD.bit.GPIO56 = 0; // Enable pull-up on GPIO18 (***)
//GpioCtrlRegs.GPBPUD.bit.GPIO57 = 0; // Enable pull-up on GPIO18 (***)
GpioCtrlRegs.GPBPUD.bit.GPIO61 = 0; // Enable pull-up on GPIO19 (SPISTEA)
