原理图

解析程序

逻辑是：
1、初始化串口和定时器10ms中断
2、循环读取一帧数据到rev_CH2O_bufferdata
3、在主函数解析数据rev_CH2O_bufferdata
4、最终的pm2.5数值就是CH2O_value

使用CH2O_value的数据即可。

PPB单位，除以1000就是ppm，再乘以1.34那么单位就是mg/m3。

#include "sys.h"
#include "delay.h"
#include "usart.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "led.h"
#include "timer.h"



char rev_CH2O_bufferdata[15];
char rev_CH2O_data_cnt = 0;
char rev_CH2O_flag = 0;
char rev_CH2O_timercnt = 0;
char rev_CH2O_sucess = 0;
uint32_t CH2O_value = 0; //PPB单位
uint8_t CH2O_verify = 0;
unsigned char CH2O_verify_cnt = 0;

int main(void) {

    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    delay_init();
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
    GPIO_PinRemapConfig(GPIO_Remap_SWJ_JTAGDisable, ENABLE);

    delay_ms(500);
    uart_init(9600);

    TIM4_Int_Init(99, 7199);                                     /* 10Khz的计数频率，计数到50为10ms */
    TIM_Cmd(TIM4, ENABLE);                                        /* 使能TIMx  开始计时 */


    while (1) {

        delay_ms(5);

         if (rev_CH2O_sucess == 1) {
                rev_CH2O_sucess = 0;
                if ((rev_CH2O_bufferdata[0] == 0xff) && (rev_CH2O_bufferdata[1] == 0x17)) {
                    CH2O_verify = 0;
                    for (CH2O_verify_cnt = 1; CH2O_verify_cnt < 8; CH2O_verify_cnt++) {
                        CH2O_verify += rev_CH2O_bufferdata[CH2O_verify_cnt];
                    }
                    CH2O_verify = ~CH2O_verify;
                    CH2O_verify += 1;
                    if (CH2O_verify == rev_CH2O_bufferdata[8]) {
                        CH2O_value = rev_CH2O_bufferdata[4] * 256 + rev_CH2O_bufferdata[5];
                    }
                }
            }
    }
}


// 10ms
void TIM4_IRQHandler(void)                                    /* TIM4中断 */
{
    if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET)  /* 检查TIM4更新中断发生与否 */
    {
        TIM_ClearITPendingBit(TIM4, TIM_IT_Update);   /* 清除TIM4更新中断标志 */
        //10ms一帧
            if (rev_CH2O_flag == 1) {
                rev_CH2O_timercnt++;
            }
            if (rev_CH2O_timercnt >= 4) {
                rev_CH2O_timercnt = 0;
                rev_CH2O_flag = 0;
                //数据处理标志
                rev_CH2O_sucess = 1;
            }

    }
}


//A9模块
void USART1_IRQHandler(void)                                                                  /* 串口1中断服务程序 */
{
    u8 receiveData;
    if (USART_GetITStatus(USART1, USART_IT_RXNE) !=
        RESET)                              /* 接收中断(接收到的数据必须是0x0d 0x0a结尾) */
    {
        receiveData = USART_ReceiveData(USART1);                                      /* 读取接收到的数据 */

        if (rev_pm25_flag == 0) {
            rev_pm25_data_cnt = 0;
            rev_pm25_bufferdata[rev_pm25_data_cnt++] = receiveData;
            rev_pm25_flag = 1;
        } else if (rev_pm25_flag == 1) {
            rev_pm25_bufferdata[rev_pm25_data_cnt++] = receiveData;
            if (rev_pm25_data_cnt >= 50) {
                rev_pm25_data_cnt = 0;
            }
        }
    }
}

帮助、问询

https://docs.qq.com/sheet/DUEdqZ2lmbmR6UVdU?tab=BB08J2