CC2640 SPI通讯的时候，这个片选端口需要设置吗？一设置程序就跑飞了。。v

/* SPI Board */
#define Board_SPI0_MISO IOID_8 //IOID_8 /* RF1.20 */ //IOID_8
#define Board_SPI0_MOSI IOID_7 //IOID_9 /* RF1.18 */ //IOID_7
#define Board_SPI0_CLK IOID_9 //IOID_10 /* RF1.16 */ //IOID_9
#define Board_SPI0_CSN PIN_UNASSIGNED //PIN_UNASSIGNED      -----------这个值是否需要设置-------------