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标题: ARM - STM32 使用11.0592MHz晶振（3） [打印本页]

作者: yuyang911220 时间: 2014-9-28 23:03 标题: ARM - STM32 使用11.0592MHz晶振（3）

#else
pllmull = pllmull >> 18;
if (pllmull != 0x0D)
{
pllmull += 2;
}
else
{ /* PLL multiplication factor = PLL input clock * 6.5 */
pllmull = 13 / 2;
}
if (pllsource == 0x00)
{/* HSI oscillator clock divided by 2 selected as PLL clock entry */
RCC_Clocks->SYSCLK_Frequency = (HSI_VALUE >> 1) * pllmull;
}
else
{/* PREDIV1 selected as PLL clock entry */
/* Get PREDIV1 clock source and division factor */
prediv1source = RCC->CFGR2 & CFGR2_PREDIV1SRC;
prediv1factor = (RCC->CFGR2 & CFGR2_PREDIV1) + 1;
if (prediv1source == 0)
{ /* HSE oscillator clock selected as PREDIV1 clock entry */
RCC_Clocks->SYSCLK_Frequency = (HSE_VALUE / prediv1factor) * pllmull;
}
else
{/* PLL2 clock selected as PREDIV1 clock entry */
/* Get PREDIV2 division factor and PLL2 multiplication factor */
prediv2factor = ((RCC->CFGR2 & CFGR2_PREDIV2) >> 4) + 1;
pll2mull = ((RCC->CFGR2 & CFGR2_PLL2MUL) >> 8 ) + 2;
RCC_Clocks->SYSCLK_Frequency = (((HSE_VALUE / prediv2factor) * pll2mull) / prediv1factor) * pllmull;
}
}
#endif /* STM32F10X_CL */
break;
default:
RCC_Clocks->SYSCLK_Frequency = HSI_VALUE;
break;
}
/* Compute HCLK, PCLK1, PCLK2 and ADCCLK clocks frequencies ----------------*/
/* Get HCLK prescaler */
tmp = RCC->CFGR & CFGR_HPRE_Set_Mask;
tmp = tmp >> 4;
presc = APBAHBPrescTable[tmp];
/* HCLK clock frequency */
RCC_Clocks->HCLK_Frequency = RCC_Clocks->SYSCLK_Frequency >> presc;
/* Get PCLK1 prescaler */
tmp = RCC->CFGR & CFGR_PPRE1_Set_Mask;
tmp = tmp >> 8;
presc = APBAHBPrescTable[tmp];
/* PCLK1 clock frequency */
RCC_Clocks->PCLK1_Frequency = RCC_Clocks->HCLK_Frequency >> presc;
/* Get PCLK2 prescaler */
tmp = RCC->CFGR & CFGR_PPRE2_Set_Mask;
tmp = tmp >> 11;
presc = APBAHBPrescTable[tmp];
/* PCLK2 clock frequency */
RCC_Clocks->PCLK2_Frequency = RCC_Clocks->HCLK_Frequency >> presc;
/* Get ADCCLK prescaler */
tmp = RCC->CFGR & CFGR_ADCPRE_Set_Mask;
tmp = tmp >> 14;
presc = ADCPrescTable[tmp];
/* ADCCLK clock frequency */
RCC_Clocks->ADCCLK_Frequency = RCC_Clocks->PCLK2_Frequency / presc;
}

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