如何设定STC15系列单片机内部时钟频率？

#define ISP_EN (1<<7) #define ISP_SWBS (1<<6) #define ISP_SWRST (1<<5) #define ISP_CMD_FAIL (1<<4) #define ISP_WAIT_1MHZ 7 #define ISP_WAIT_2MHZ 6 #define ISP_WAIT_3MHZ 5 #define ISP_WAIT_6MHZ 4 #define ISP_WAIT_12MHZ 3 #define ISP_WAIT_20MHZ 2 #define ISP_WAIT_24MHZ 1 #define ISP_WAIT_30MHZ 0 #if (MAIN_Fosc >= 24000000L) #define ISP_WAIT_FREQUENCY ISP_WAIT_30MHZ #elif (MAIN_Fosc >= 20000000L) #define ISP_WAIT_FREQUENCY ISP_WAIT_24MHZ #elif (MAIN_Fosc >= 12000000L) #define ISP_WAIT_FREQUENCY ISP_WAIT_20MHZ #elif (MAIN_Fosc >= 6000000L) #define ISP_WAIT_FREQUENCY ISP_WAIT_12MHZ #elif (MAIN_Fosc >= 3000000L) #define ISP_WAIT_FREQUENCY ISP_WAIT_6MHZ #elif (MAIN_Fosc >= 2000000L) #define ISP_WAIT_FREQUENCY ISP_WAIT_3MHZ #elif (MAIN_Fosc >= 1000000L) #define ISP_WAIT_FREQUENCY ISP_WAIT_2MHZ #else #define ISP_WAIT_FREQUENCY ISP_WAIT_1MHZ #endif

需要这么多吗