GD32主频108M，而STM32推荐工作频率为72M。所以使用STM32估计固件库开发得加入108M时钟的配置。采用如下步骤来完成，如果哪里有错误还请网友及时指出
1、添加几项宏定义：（system_stm32f10x.h）
//加入108MHz #if defined (STM32F10X_LD_VL) || (defined STM32F10X_MD_VL) || (defined STM32F10X_HD_VL) /* #define SYSCLK_FREQ_HSE HSE_VALUE */ #define SYSCLK_FREQ_24MHz 24000000 #else /* #define SYSCLK_FREQ_HSE HSE_VALUE */ /* #define SYSCLK_FREQ_24MHz 24000000 */ /* #define SYSCLK_FREQ_36MHz 36000000 */ /* #define SYSCLK_FREQ_48MHz 48000000 */ /* #define SYSCLK_FREQ_56MHz 56000000 */ /* #define SYSCLK_FREQ_72MHz 72000000 */ #define SYSCLK_FREQ_108MHz 108000000 #endif
#ifdef SYSCLK_FREQ_HSE uint32_t SystemCoreClock = SYSCLK_FREQ_HSE; /*!< System Clock Frequency (Core Clock) */ #elif defined SYSCLK_FREQ_24MHz uint32_t SystemCoreClock = SYSCLK_FREQ_24MHz; /*!< System Clock Frequency (Core Clock) */ #elif defined SYSCLK_FREQ_36MHz uint32_t SystemCoreClock = SYSCLK_FREQ_36MHz; /*!< System Clock Frequency (Core Clock) */ #elif defined SYSCLK_FREQ_48MHz uint32_t SystemCoreClock = SYSCLK_FREQ_48MHz; /*!< System Clock Frequency (Core Clock) */ #elif defined SYSCLK_FREQ_56MHz uint32_t SystemCoreClock = SYSCLK_FREQ_56MHz; /*!< System Clock Frequency (Core Clock) */ #elif defined SYSCLK_FREQ_72MHz uint32_t SystemCoreClock = SYSCLK_FREQ_72MHz; /*!< System Clock Frequency (Core Clock) */ #elif defined SYSCLK_FREQ_108MHz uint32_t SystemCoreClock = SYSCLK_FREQ_108MHz; #else /*!< HSI Selected as System Clock source */ uint32_t SystemCoreClock = HSI_VALUE; /*!< System Clock Frequency (Core Clock) */ #endif
#ifdef SYSCLK_FREQ_HSE static void SetSysClockToHSE(void); #elif defined SYSCLK_FREQ_24MHz static void SetSysClockTo24(void); #elif defined SYSCLK_FREQ_36MHz static void SetSysClockTo36(void); #elif defined SYSCLK_FREQ_48MHz static void SetSysClockTo48(void); #elif defined SYSCLK_FREQ_56MHz static void SetSysClockTo56(void); #elif defined SYSCLK_FREQ_72MHz static void SetSysClockTo72(void); #elif defined SYSCLK_FREQ_108MHz static void SetSysClockTo108(void); #endif
2、完成void SetSysClockTo108(void)函数，以SetSysClockTo72为参照，在其基础上修改。因为GD32中倍频系数由5个位组成。所以先在stm32f10x.h里添加几项东西：
/*!< PLLMUL configuration *///11 1100 #define RCC_CFGR_PLLMULL ((uint32_t)0x003C0000) /*!< PLLMUL[3:0] bits (PLL multiplication factor) */ #define RCC_CFGR_PLLMULL_0 ((uint32_t)0x00040000) /*!< Bit 0 */ #define RCC_CFGR_PLLMULL_1 ((uint32_t)0x00080000) /*!< Bit 1 */ #define RCC_CFGR_PLLMULL_2 ((uint32_t)0x00100000) /*!< Bit 2 */ #define RCC_CFGR_PLLMULL_3 ((uint32_t)0x00200000) /*!< Bit 3 */ #define RCC_CFGR_PLLMULL_4 ((uint32_t)0x08000000) /*!< Bit 4 GD32*/
是采用 8M / 2 * 27 = 108MHz 所以添加一个x27的宏
#define RCC_CFGR_PLLMULL4 ((uint32_t)0x00080000) /*!< PLL input clock * 4 */ #define RCC_CFGR_PLLMULL5 ((uint32_t)0x000C0000) /*!< PLL input clock * 5 */ #define RCC_CFGR_PLLMULL6 ((uint32_t)0x00100000) /*!< PLL input clock * 6 */ #define RCC_CFGR_PLLMULL7 ((uint32_t)0x00140000) /*!< PLL input clock * 7 */ #define RCC_CFGR_PLLMULL8 ((uint32_t)0x00180000) /*!< PLL input clock * 8 */ #define RCC_CFGR_PLLMULL9 ((uint32_t)0x001C0000) /*!< PLL input clock * 9 */ #define RCC_CFGR_PLLMULL6_5 ((uint32_t)0x00340000) /*!< PLL input clock * 6.5 */ #define RCC_CFGR_PLLMULL27 ((uint32_t)(RCC_CFGR_PLLMULL_4 | RCC_CFGR_PLLMULL_3 | RCC_CFGR_PLLMULL_1))
函数如下：
#elif defined SYSCLK_FREQ_108MHz
static void SetSysClockTo108(void)
{
__IO uint32_t StartUpCounter = 0, HSEStatus = 0;
/* SYSCLK, HCLK, PCLK2 and PCLK1 configuration ---------------------------*/
/* Enable HSE */
RCC->CR |= ((uint32_t)RCC_CR_HSEON);
/* Wait till HSE is ready and if Time out is reached exit */
do
{
HSEStatus = RCC->CR & RCC_CR_HSERDY;
StartUpCounter++;
} while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));
if ((RCC->CR & RCC_CR_HSERDY) != RESET)
{
HSEStatus = (uint32_t)0x01;
}
else
{
HSEStatus = (uint32_t)0x00;
}
if (HSEStatus == (uint32_t)0x01)
{
/* Enable Prefetch Buffer */
FLASH->ACR |= FLASH_ACR_PRFTBE;
/* Flash 2 wait state */
FLASH->ACR &= (uint32_t)((uint32_t)~FLASH_ACR_LATENCY);
FLASH->ACR |= (uint32_t)FLASH_ACR_LATENCY_2;
/* HCLK = SYSCLK */
RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;
/* PCLK2 = HCLK */
RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE2_DIV1;
/* PCLK1 = HCLK */
RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV2;
#ifdef STM32F10X_CL
/* Configure PLLs ------------------------------------------------------*/
/* PLL2 configuration: PLL2CLK = (HSE / 5) * 8 = 40 MHz */
/* PREDIV1 configuration: PREDIV1CLK = PLL2 / 5 = 8 MHz */
RCC->CFGR2 &= (uint32_t)~(RCC_CFGR2_PREDIV2 | RCC_CFGR2_PLL2MUL |
RCC_CFGR2_PREDIV1 | RCC_CFGR2_PREDIV1SRC);
RCC->CFGR2 |= (uint32_t)(RCC_CFGR2_PREDIV2_DIV5 | RCC_CFGR2_PLL2MUL8 |
RCC_CFGR2_PREDIV1SRC_PLL2 | RCC_CFGR2_PREDIV1_DIV5);
/* Enable PLL2 */
RCC->CR |= RCC_CR_PLL2ON;
/* Wait till PLL2 is ready */
while((RCC->CR & RCC_CR_PLL2RDY) == 0)
{
}
/* PLL configuration: PLLCLK = PREDIV1 / 2 * 27 = 108 MHz */
RCC->CFGR &= (uint32_t)~(RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLSRC | RCC_CFGR_PLLMULL | RCC_CFGR_PLLMULL_4);
RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLXTPRE_PREDIV1_Div2 | RCC_CFGR_PLLSRC_PREDIV1 |
RCC_CFGR_PLLMULL27);
#else
/* PLL configuration: PLLCLK = PREDIV1 / 2 * 27 = 108 MHz */
RCC->CFGR &= (uint32_t)~(RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLSRC | RCC_CFGR_PLLMULL | RCC_CFGR_PLLMULL_4);
RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLXTPRE_PREDIV1_Div2 | RCC_CFGR_PLLSRC_PREDIV1 |
RCC_CFGR_PLLMULL27);
#endif /* STM32F10X_CL */
/* Enable PLL */
RCC->CR |= RCC_CR_PLLON;
/* Wait till PLL is ready */
while((RCC->CR & RCC_CR_PLLRDY) == 0)
{
}
/* Select PLL as system clock source */
RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;
/* Wait till PLL is used as system clock source */
while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)0x08)
{
}
}
else
{ /* If HSE fails to start-up, the application will have wrong clock
configuration. User can add here some code to deal with this error */
}
}
#endif
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