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你写的语句是没有错，但是在文档TMS320x2833x, 2823x System Control and Interrupts Reference Guide中有这样的说明：
When using the GPxDAT register to change the level of an output pin, you should be cautious not to accidentally change the level of another pin. For example, if you mean to change the output latch level of GPIOA0 by writing to the GPADAT register bit 0, using a read-modify-write instruction. The problem can occur if another I/O port A signal changes level between the read and the write stage of the instruction. You can also change the state of that output latch. You can avoid this scenario by using the GPxSET, GPxCLEAR, and GPxTOGGLE registers to load the output latch instead.
即直接写GPADAT寄存器可能引起其他引脚电平的变化，建议使用GPxSET, GPxCLEAR, and GPxTOGGLE
