外部是8M无源晶振,采用PLL,倍频到48MHz的,
system_gd32f30x.c中这样定义的:
/* use HXTAL(XD series CK_HXTAL = 8M, CL series CK_HXTAL = 25M) */
//#define __SYSTEM_CLOCK_HXTAL (uint32_t)(__HXTAL)
#define __SYSTEM_CLOCK_48M_PLL_HXTAL (uint32_t)(48000000)
//#define __SYSTEM_CLOCK_72M_PLL_HXTAL (uint32_t)(72000000)
//#define __SYSTEM_CLOCK_108M_PLL_HXTAL (uint32_t)(108000000)
//#define __SYSTEM_CLOCK_120M_PLL_HXTAL (uint32_t)(120000000)
系统初始化的时候,也是调用这个函数static void system_clock_48m_hxtal(void)
这都是GD官网上下载的库例程中
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