GD32外接16Mhz晶振，计算后倍频是小数，如何解决？

只看该作者 · 2021-10-5 17:29

#if (defined(GD32F10X_MD) || defined(GD32F10X_HD) || defined(GD32F10X_XD))
/* select HXTAL/2 as clock source */
RCU_CFG0 &= ~(RCU_CFG0_PLLSEL | RCU_CFG0_PREDV0);
RCU_CFG0 |= (RCU_PLLSRC_HXTAL | RCU_CFG0_PREDV0);

/* CK_PLL = (CK_HXTAL/2) * 27 = 108 MHz */
RCU_CFG0 &= ~(RCU_CFG0_PLLMF | RCU_CFG0_PLLMF_4);
//RCU_CFG0 |= RCU_PLL_MUL27;
//这里CK_HXTAL为16MHz,所以计算倍频得13.5，那么应该选RCU_PLL_MUL13还是RCU_PLL_MUL14呢？
RCU_CFG0 |= RCU_PLL_MUL13;//？？RCU_PLL_MUL14？？