stm3按键循环，另一个按键切换并执行另一个循环代码，用标准库写

以下是一个基于标准库的示例代码，实现了STM32的按键循环和切换功能。在此示例代码中，我们使用了两个按键，一个用于切换循环代码，另一个用于执行循环代码。当按下第一个按键时，我们会切换到第二个循环代码，并在串口中输出一条提示消息。当按下第二个按键时，我们会回到第一个循环代码，并再次在串口中输出一条提示消息。

#include "stm32f10x.h"
#include "stm32f10x_gpio.h"
#include "stm32f10x_rcc.h"
#include "stm32f10x_usart.h"
#include "stm32f10x_exti.h"
#include "misc.h"

#define LED_GPIO GPIOC
#define LED_PIN GPIO_Pin_13
#define BUTTON_GPIO GPIOA
#define BUTTON1_PIN GPIO_Pin_0
#define BUTTON2_PIN GPIO_Pin_1

volatile uint8_t loop1_flag = 0;
volatile uint8_t loop2_flag = 0;

void init_gpio(void);
void init_usart(void);
void init_exti(void);
void loop1(void);
void loop2(void);

int main(void)
{
    init_gpio();
    init_usart();
    init_exti();

    while(1)
    {
        if(loop1_flag)
        {
            loop1();
        }
        else if(loop2_flag)
        {
            loop2();
        }
    }
}

void init_gpio(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Pin = LED_PIN;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(LED_GPIO, &GPIO_InitStructure);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
    GPIO_InitStructure.GPIO_Pin = BUTTON1_PIN | BUTTON2_PIN;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(BUTTON_GPIO, &GPIO_InitStructure);
}

void init_usart(void)
{
    USART_InitTypeDef USART_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);

    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    USART_InitStructure.USART_BaudRate = 9600;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

void init_exti(void)
{
    EXTI_InitTypeDef EXTI_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);
    EXTI_InitStructure.EXTI_Line = EXTI_Line0;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource1);
    EXTI_InitStructure.EXTI_Line = EXTI_Line1;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);

    NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    NVIC_InitStructure.NVIC_IRQChannel = EXTI1_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void loop1(void)
{
    static uint8_t led_state = 0;

    GPIO_WriteBit(LED_GPIO, LED_PIN, led_state ? Bit_SET : Bit_RESET);
    led_state = !led_state;

    USART_SendData(USART1, 'L');
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
}

void loop2(void)
{
    static uint8_t led_state = 0;

    GPIO_WriteBit(LED_GPIO, LED_PIN, led_state ? Bit_SET : Bit_RESET);
    led_state = !led_state;

    USART_SendData(USART1, 'H');
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
}

void EXTI0_IRQHandler(void)
{
    if (EXTI_GetITStatus(EXTI_Line0) != RESET)
    {
        EXTI_ClearITPendingBit(EXTI_Line0);

        loop2_flag = !loop2_flag;
        loop1_flag = !loop2_flag;

        if(loop2_flag)
        {
            USART_SendData(USART1, 'S');
            while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
        }
        else
        {
            USART_SendData(USART1, 'R');
            while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
        }
    }
}

void EXTI1_IRQHandler(void)
{
    if (EXTI_GetITStatus(EXTI_Line1) != RESET)
    {
        EXTI_ClearITPendingBit(EXTI_Line1);

        if(loop1_flag)
        {
            loop1();
        }
        else if(loop2_flag)
        {
            loop2();
        }
    }
}

在以上示例代码中，我们使用了一个循环标志位 `loop1_flag` 和 `loop2_flag` 来切换循环代码。当 `loop1_flag` 为 1 时，我们执行 `loop1` 函数；当 `loop2_flag` 为 1 时，我们执行 `loop2` 函数。在 `EXTI0_IRQHandler` 函数中，我们检测到第一个按键按下时，会切换循环标志位，并在串口中输出提示消息。在 `EXTI1_IRQHandler` 函数中，我们检测到第二个按键按下时，会执行当前循环代码。