stm32f103zet6连接mq2传感器串口打印采样值

以下是使用STM32F103ZET6连接MQ2传感器并通过串口打印采样值的示例代码：

#include "stm32f10x.h"

#define MQ2_PIN GPIO_Pin_0
#define MQ2_PORT GPIOA

void init_GPIO(void);
void init_USART1(void);
void USART_puts(USART_TypeDef* USARTx, volatile char *s);

int main(void)
{
    volatile uint16_t mq2_value;

    init_GPIO();
    init_USART1();

    while (1)
    {
        mq2_value = ADC_GetConversionValue(ADC1);

        char str[10];
        sprintf(str, "%d\n", mq2_value);
        USART_puts(USART1, str);

        delay_ms(1000);
    }
}

void init_GPIO(void)
{
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitTypeDef GPIO_InitStructure;

    GPIO_InitStructure.GPIO_Pin = MQ2_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(MQ2_PORT, &GPIO_InitStructure);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
    RCC_ADCCLKConfig(RCC_PCLK2_Div6);

    ADC_InitTypeDef ADC_InitStructure;

    ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
    ADC_InitStructure.ADC_ScanConvMode = DISABLE;
    ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
    ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
    ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
    ADC_InitStructure.ADC_NbrOfChannel = 1;
    ADC_Init(ADC1, &ADC_InitStructure);

    ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_239Cycles5);

    ADC_Cmd(ADC1, ENABLE);
    ADC_ResetCalibration(ADC1);

    while(ADC_GetResetCalibrationStatus(ADC1));
    ADC_StartCalibration(ADC1);

    while(ADC_GetCalibrationStatus(ADC1));
}

void init_USART1(void)
{
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, 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_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    USART_InitTypeDef USART_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_Tx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

void USART_puts(USART_TypeDef* USARTx, volatile char *s)
{
    while(*s)
    {
        while(USART_GetFlagStatus(USARTx, USART_FLAG_TXE) == RESET);
        USART_SendData(USARTx, *s);
        *s++;
    }
}

void delay_ms(uint16_t ms)
{
    volatile uint32_t count = ms * 1000;
    while(count--);
}

该代码使用ADC采集MQ2传感器的模拟输出值，并通过串口将采样值打印出来。在初始化函数中，使用GPIO初始化MQ2传感器的输入引脚，使用ADC初始化ADC1并配置其采样通道为PA0。在主函数中，通过ADC_GetConversionValue函数获取ADC转换后的值，并使用sprintf将其转换为字符串格式，最后通过USART_puts函数将字符串发送到串口。由于MQ2传感器的响应速度较慢，为避免多次读取同一采样值，使用delay_ms函数添加延时。