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13-2修改主频&睡眠模式&停止模式&待机模式

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修改主频

system_stm32f10x.c

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1.  This file provides two functions and one global variable to be called from 
  *     user application:
  *      - SystemInit(): Setups the system clock (System clock source, PLL Multiplier
  *                      factors, AHB/APBx prescalers and Flash settings). 
  *                      This function is called at startup just after reset and 
  *                      before branch to main program. This call is made inside
  *                      the "startup_stm32f10x_xx.s" file.
  *
  *      - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
  *                                  by the user application to setup the SysTick 
  *                                  timer or configure other parameters.
  *                                     
  *      - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
  *                                 be called whenever the core clock is changed
  *                                 during program execution.
  *
  * 2. After each device reset the HSI (8 MHz) is used as system clock source.
  *    Then SystemInit() function is called, in "startup_stm32f10x_xx.s" file, to
  *    configure the system clock before to branch to main program.
  *
  * 3. If the system clock source selected by user fails to startup, the SystemInit()
  *    function will do nothing and HSI still used as system clock source. User can 
  *    add some code to deal with this issue inside the SetSysClock() function.
  *
  * 4. The default value of HSE crystal is set to 8 MHz (or 25 MHz, depedning on
  *    the product used), refer to "HSE_VALUE" define in "stm32f10x.h" file. 
  *    When HSE is used as system clock source, directly or through PLL, and you
  *    are using different crystal you have to adapt the HSE value to your own
  *    configuration.

SystemInit()这个函数用来配置时钟树，在main函数之前自动调用

SystemCoreClock表示主频频率的值，显示此变量，可以知道目前主频的值。

SystemCoreClockUpdate()更新SystemCoreClock，因为这个变量只要最开始的一次赋值，改变主频频率，该值不会跟着改变。

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#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
#endif

想要修改主频值，解除注释。默认的主频是72000000（72M）

main.c

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#include "stm32f10x.h"                  // Device header
#include "Delay.h"
#include "OLED.h"

int main(void)
{
	OLED_Init();
	OLED_ShowString(1,1,"SYSCLK:");
	OLED_ShowNum(1,8,SystemCoreClock,8);//显示当前的主频值，可以在system_stm32f10x.c中修改
	
	while(1)
	{
		//在默认的72M主频下，Running每500ms显示一次，修改主频，显示时间会变化，因为主频改变了。比如主频改成36M，Runing每1S显示一次。如果想要修改主频之后，Running仍500ms显示一次，需要修改Delay函数。可见不能随意修改主频。
		OLED_ShowString(2,1,"Running");
		Delay_ms(500);
		OLED_ShowString(2,1,"         ");
		Delay_ms(500);
	}
}

睡眠模式+串口发送+接收

因为主循环一直在运行，空闲时运行没有意义，还费电。
因此靠中断触发，没有中断就没作用的程序，可以加入低功耗模式。

由于程序需要使用串口USART硬件电路接收数据，只能使用睡眠模式，不能使用停止模式或待机模式，因为停止模式和待机模式下CPU和外设都不能运行，无法正常接收串口数据。

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#include "stm32f10x.h"                  // Device header
#include "Delay.h"
#include "OLED.h"
#include "Serial.h"
uint8_t RxData;
int main(void)
{
	//初始化，配置串口
	OLED_Init();
	OLED_ShowString(1,1,"RxData:");
	Serial_Init();
	while (1)
	{
		if(Serial_GetRxFlag() == 1)
		{
			RxData = Serial_GetRxData();
			Serial_SendByte(RxData);
			OLED_ShowHexNum(1,8,RxData,2);
		}
		OLED_ShowString(2,1,"Running");
		Delay_ms(100);
		OLED_ShowString(2,1,"       ");
		Delay_ms(100);
		
		__WFI();//中断唤醒
		
		//__WFE();//事件唤醒
	}
}

通过串口给单片机发送数据，每发送一次数据，进入中断，单片机会被唤醒，Running闪烁一次。

停止模式+对射式红外传感器计次

对射式红外传感器计次使用外部中断触发唤醒，可以进入更省电的停止模式。
在停止模式下，1.8V区域时钟关闭，CPU和外设都没有时钟，但是外部中断的工作不需要时钟。

常用函数

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void PWR_DeInit(void);

恢复PWR缺省配置

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void PWR_BackupAccessCmd(FunctionalState NewState);

使能后备区域访问

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void PWR_PVDCmd(FunctionalState NewState);

使能PVD功能

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void PWR_PVDLevelConfig(uint32_t PWR_PVDLevel);

配置PVD的阈值电压

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void PWR_WakeUpPinCmd(FunctionalState NewState);

使能位于PA0位置的WKUP引脚，配合待机模式使用

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void PWR_EnterSTOPMode(uint32_t PWR_Regulator, uint8_t PWR_STOPEntry);

进入停止模式

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void PWR_EnterSTANDBYMode(void);

进入待机模式

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FlagStatus PWR_GetFlagStatus(uint32_t PWR_FLAG);

获取标志位

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void PWR_ClearFlag(uint32_t PWR_FLAG);

清除标志位

main.c

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#include "stm32f10x.h"                  // Device header
#include "Delay.h"
#include "OLED.h"
#include "CountSensor.h"


int main(void)
{
	OLED_Init();
	CountSensor_Init();
	
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR,ENABLE);//开启PWR外设的时钟
	
	OLED_ShowString(1,1,"Count:");
	
	while(1)
	{
		OLED_ShowNum(1,7,CountSensor_Get(),5);
		
		OLED_ShowString(2,1,"Running");
		Delay_ms(100);
		OLED_ShowString(2,1,"       ");
		Delay_ms(100);
		
		PWR_EnterSTOPMode(PWR_Regulator_ON,PWR_STOPEntry_WFI);//进入停止模式
		SystemInit();//配置时钟
	}
}

待机模式 + 实时时钟

main.c

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#include "stm32f10x.h"                  // Device header
#include "Delay.h"
#include "OLED.h"
#include "MyRTC.h"

int main(void)
{
	OLED_Init();
	MyRTC_Init();
	
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR,ENABLE);//开启PWR时钟

	
	OLED_ShowString(1,1,"CNT:");
	OLED_ShowString(2,1,"ALR:");
	OLED_ShowString(3,1,"ALRF:");
	
	PWR_WakeUpPinCmd(ENABLE);//WKUP引脚唤醒
	
	uint32_t Alarm = RTC_GetCounter() + 10;
	RTC_SetAlarm(RTC_GetCounter() + 10);
	OLED_ShowNum(2,6,Alarm,10);
	
	while(1)
	{
		OLED_ShowNum(1,6,RTC_GetCounter(),10);
		OLED_ShowNum(3,6,RTC_GetFlagStatus(RTC_FLAG_ALR),1);
		
		OLED_ShowString(4,1,"Running");
		Delay_ms(100);
		OLED_ShowString(4,1,"       ");
		Delay_ms(100);
		
		PWR_EnterSTANDBYMode();//进入待机模式
	}
	
}

进入待机模式后，闹钟触发一次，程序从头开始执行。