【GD32F350开发分享二】GD32F350时钟配置，非常重要

2万 · 2020-11-12 09:50

大家应该都知道，微控制器最重要的就是时钟频率，时钟频率会影响指令周期、定时器、RTC等等所有涉及时钟的总线。
GD32F350开发板的外部高速时钟8MHZ晶振和外部低速时钟32.768KHZ晶振没有焊接，大家有需要自行焊接。
我用的是内部时钟8MHZ，当然，如果需要用时钟频率进行定时器中断设置的，建议使用外部晶振，因为外部晶振精度高，偏移量小，但是缺点在于功耗就大了，内部时钟功耗低，但是精度会差一些；
以下是我的时钟配置

/* system frequency define */
#define __IRC8M          (IRC8M_VALUE)          /* internal 8 MHz RC oscillator frequency */
#define __HXTAL          (HXTAL_VALUE)          /* high speed crystal oscillator frequency */
#define __SYS_OSC_CLK    (__IRC8M)             /* main oscillator frequency */

/* select a system clock by uncommenting the following line */
#if defined (GD32F330)
//#define __SYSTEM_CLOCK_8M_HXTAL             (__HXTAL)
//#define __SYSTEM_CLOCK_8M_IRC8M             (__IRC8M)
//#define __SYSTEM_CLOCK_72M_PLL_HXTAL       (uint32_t)(72000000)
//#define __SYSTEM_CLOCK_72M_PLL_IRC8M_DIV2 (uint32_t)(72000000)
//#define __SYSTEM_CLOCK_72M_PLL_IRC48M_DIV2    (uint32_t)(72000000)
#define __SYSTEM_CLOCK_84M_PLL_HXTAL          (uint32_t)(84000000)
//#define __SYSTEM_CLOCK_84M_PLL_IRC8M_DIV2 (uint32_t)(84000000)
#endif /* GD32F330 */

#if defined (GD32F350)
//#define __SYSTEM_CLOCK_8M_HXTAL             (__HXTAL)
#define __SYSTEM_CLOCK_8M_IRC8M             (__IRC8M)
//#define __SYSTEM_CLOCK_72M_PLL_HXTAL       (uint32_t)(72000000)
//#define __SYSTEM_CLOCK_72M_PLL_IRC8M_DIV2 (uint32_t)(72000000)
//#define __SYSTEM_CLOCK_84M_PLL_HXTAL       (uint32_t)(84000000)
//#define __SYSTEM_CLOCK_84M_PLL_IRC8M_DIV2 (uint32_t)(84000000)
//#define __SYSTEM_CLOCK_96M_PLL_HXTAL       (uint32_t)(96000000)
//#define __SYSTEM_CLOCK_96M_PLL_IRC8M_DIV2    (uint32_t)(96000000)
//#define __SYSTEM_CLOCK_96M_PLL_IRC48M_DIV2    (uint32_t)(96000000)
//#define __SYSTEM_CLOCK_108M_PLL_HXTAL       (uint32_t)(108000000)
//#define __SYSTEM_CLOCK_108M_PLL_IRC8M_DIV2 (uint32_t)(108000000)
#endif /* GD32F350 */

#define SEL_IRC8M    0x00
#define SEL_HXTAL    0x01
#define SEL_PLL       0x02

/* set the system clock frequency and declare the system clock configuration function */
#ifdef __SYSTEM_CLOCK_8M_HXTAL
uint32_t SystemCoreClock = __SYSTEM_CLOCK_8M_HXTAL;
static void system_clock_8m_hxtal(void);

#elif defined (__SYSTEM_CLOCK_72M_PLL_HXTAL)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_72M_PLL_HXTAL;
static void system_clock_72m_hxtal(void);

#elif defined (__SYSTEM_CLOCK_72M_PLL_IRC8M_DIV2)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_72M_PLL_IRC8M_DIV2;
static void system_clock_72m_irc8m(void);

#elif defined (__SYSTEM_CLOCK_72M_PLL_IRC48M_DIV2)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_72M_PLL_IRC48M_DIV2;
static void system_clock_72m_irc48m(void);

#elif defined (__SYSTEM_CLOCK_84M_PLL_HXTAL)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_84M_PLL_HXTAL;
static void system_clock_84m_hxtal(void);

#elif defined (__SYSTEM_CLOCK_84M_PLL_IRC8M_DIV2)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_84M_PLL_IRC8M_DIV2;
static void system_clock_84m_irc8m(void);

#elif defined (__SYSTEM_CLOCK_96M_PLL_HXTAL)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_96M_PLL_HXTAL;
static void system_clock_96m_hxtal(void);

#elif defined (__SYSTEM_CLOCK_96M_PLL_IRC8M_DIV2)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_96M_PLL_IRC8M_DIV2;
static void system_clock_96m_irc8m(void);

#elif defined (__SYSTEM_CLOCK_96M_PLL_IRC48M_DIV2)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_96M_PLL_IRC48M_DIV2;
static void system_clock_96m_irc48m(void);

#elif defined (__SYSTEM_CLOCK_108M_PLL_HXTAL)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_108M_PLL_HXTAL;
static void system_clock_108m_hxtal(void);

#elif defined (__SYSTEM_CLOCK_108M_PLL_IRC8M_DIV2)
uint32_t SystemCoreClock = __SYSTEM_CLOCK_108M_PLL_IRC8M_DIV2;
static void system_clock_108m_irc8m(void);

#else
uint32_t SystemCoreClock = __SYSTEM_CLOCK_8M_IRC8M;
static void system_clock_8m_irc8m(void);
#endif /* __SYSTEM_CLOCK_8M_HXTAL */

/* configure the system clock */
static void system_clock_config(void);

/*!
\brief    setup the microcontroller system, initialize the system
\param[in]  none
\param[out] none
\retval    none
*/
void SystemInit (void)
{
/* enable IRC8M */
RCU_CTL0 |= RCU_CTL0_IRC8MEN;
while(0U == (RCU_CTL0 & RCU_CTL0_IRC8MSTB)){
}
/* reset RCU */
RCU_CFG0 &= ~(RCU_CFG0_SCS | RCU_CFG0_AHBPSC | RCU_CFG0_APB1PSC | RCU_CFG0_APB2PSC |\
               RCU_CFG0_ADCPSC | RCU_CFG0_CKOUTSEL | RCU_CFG0_CKOUTDIV | RCU_CFG0_PLLDV);
RCU_CFG0 &= ~(RCU_CFG0_PLLSEL | RCU_CFG0_PLLMF | RCU_CFG0_PLLMF4 | RCU_CFG0_PLLDV);
#if (defined(GD32F350))
RCU_CFG0 &= ~(RCU_CFG0_USBFSPSC);
RCU_CFG2 &= ~(RCU_CFG2_CECSEL | RCU_CFG2_USBFSPSC2);
#endif /* GD32F350 */
RCU_CTL0 &= ~(RCU_CTL0_HXTALEN | RCU_CTL0_CKMEN | RCU_CTL0_PLLEN | RCU_CTL0_HXTALBPS);
RCU_CFG1 &= ~(RCU_CFG1_PREDV | RCU_CFG1_PLLMF5 | RCU_CFG1_PLLPRESEL);
RCU_CFG2 &= ~(RCU_CFG2_USART0SEL | RCU_CFG2_ADCSEL);
RCU_CFG2 &= ~RCU_CFG2_IRC28MDIV;
RCU_CFG2 &= ~RCU_CFG2_ADCPSC2;
RCU_CTL1 &= ~RCU_CTL1_IRC28MEN;
RCU_ADDCTL &= ~RCU_ADDCTL_IRC48MEN;
RCU_INT = 0x00000000U;
RCU_ADDINT = 0x00000000U;
/* configure system clock */
system_clock_config();
}

/*!
\brief    configure the system clock
\param[in]  none
\param[out] none
\retval    none
*/
static void system_clock_config(void)
{
#ifdef __SYSTEM_CLOCK_8M_HXTAL
system_clock_8m_hxtal();
#elif defined (__SYSTEM_CLOCK_72M_PLL_HXTAL)
system_clock_72m_hxtal();
#elif defined (__SYSTEM_CLOCK_72M_PLL_IRC8M_DIV2)
system_clock_72m_irc8m();
#elif defined (__SYSTEM_CLOCK_72M_PLL_IRC48M_DIV2)
system_clock_72m_irc48m();
#elif defined (__SYSTEM_CLOCK_84M_PLL_HXTAL)
system_clock_84m_hxtal();
#elif defined (__SYSTEM_CLOCK_84M_PLL_IRC8M_DIV2)
system_clock_84m_irc8m();
#elif defined (__SYSTEM_CLOCK_96M_PLL_HXTAL)
system_clock_96m_hxtal();
#elif defined (__SYSTEM_CLOCK_96M_PLL_IRC8M_DIV2)
system_clock_96m_irc8m();
#elif defined (__SYSTEM_CLOCK_96M_PLL_IRC48M_DIV2)
system_clock_96m_irc48m();
#elif defined (__SYSTEM_CLOCK_108M_PLL_HXTAL)
system_clock_108m_hxtal();
#elif defined (__SYSTEM_CLOCK_108M_PLL_IRC8M_DIV2)
system_clock_108m_irc8m();
#else
system_clock_8m_irc8m();
#endif /* __SYSTEM_CLOCK_8M_HXTAL */
}
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