#include <SoftwareSerial.h>

#define SDS_RX 2  // SDS011 TX pin connected to Arduino RX pin
#define SDS_TX 3  // SDS011 RX pin connected to Arduino TX pin

SoftwareSerial sds(SDS_RX, SDS_TX);

void setup() {
  Serial.begin(9600);
  sds.begin(9600);
}

void loop() {
  if (sds.available() > 0) {
    if (sds.read() == 0xAA) {  // Start byte of data packet
      byte buf[10];
      uint8_t sum = 0;

      // Read the rest of the data packet
      if (sds.readBytes(buf, 10) == 10) {
        for (int i = 2; i < 8; i++) {
          sum += buf[i];
        }

        // Check if the checksum is correct
        if (sum == buf[8]) {
          int pm25 = (buf[3] * 256 + buf[2]);
          int pm10 = (buf[5] * 256 + buf[4]);
          
          // Print PM2.5 and PM10 values
          Serial.print("PM2.5: ");
          Serial.print(pm25);
          Serial.print(" ug/m3\t");
          Serial.print("PM10: ");
          Serial.print(pm10);
          Serial.println(" ug/m3");
        }
      }
    }
  }
}
/*In this code:

We use the SoftwareSerial library to create a software serial port for communication with the SDS011 sensor.
We define the RX and TX pins for the SDS011 (SDS_RX and SDS_TX).
In the setup function, we initialize both the hardware serial port (for communication with the computer) and the software serial port (for communication with the SDS011).
In the loop function, we check if there is data available on the software serial port. If so, we check if the start byte of the data packet is received (0xAA). If yes, we read the rest of the data packet and calculate the checksum to verify the data integrity. If the checksum is correct, we extract the PM2.5 and PM10 values from the data packet and print them to the Serial Monitor.
Make sure you have connected the SDS011 TX pin to Arduino RX pin (SDS_RX) and SDS011 RX pin to Arduino TX pin (SDS_TX). Also, remember to power the SDS011 properly according to its specifications.*/