OnAirDetection

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Direct Read From Serial Port

Arduino mega2560 Code:

void setup() {
  pinMode(0,INPUT_PULLUP); 
  pinMode(1,INPUT_PULLUP); 
}

void loop() {
}

This code will turn mega2560 into a USB-TTL transmitter, thus you could directly read from the serial port and display them in hex mode:

# cat /dev/ttyACM0 | xxd -p -c 9
ffff01270005020534
ffff01270005020534
ffff01270005020534
ffff01270005020534
....

According to the reference manual,

we know the air is 0.05 mg/m3.

Read From Arduino Mega2560

Code:

void setup() {
  // initialize both serial ports:
  Serial.begin(9600);
  Serial2.begin(9600,SERIAL_8N1);

    while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


    while (!Serial2) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  // prints title with ending line break
  Serial.println("ASCII Table ~ Character Map");
}

void loop() {


   for (int i=0; i<9; i++) {

    while(!Serial2.available()); // wait for a character
    int incomingByte = Serial2.read();
    Serial.print(incomingByte,HEX);
    Serial.print(' ');

   }
   Serial.println();
}

Result:

Problem

How to detect the result? Start from FF FF?

Should be

Fixed-Bug

Every time it will print starting with FF FF:

int incomingByte=0;
int vanishByte=0;

void setup() {
  // initialize both serial ports:
  Serial.begin(9600);
  Serial2.begin(9600,SERIAL_8N1);

    while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


    while (!Serial2) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  // prints title with ending line break
  Serial.println("ASCII Table ~ Character Map");
}

void loop() {

    //Serial.println();
   //for (int i=0; i<9; i++) {
    while(!Serial2.available()); // wait for a character
    vanishByte = incomingByte;
    incomingByte = Serial2.read();
    if((incomingByte == 0xFF) && (vanishByte != 0xFF))
    {
      Serial.println();
    }
    Serial.print(incomingByte,HEX);
    Serial.print(' ');
   //}
   //Serial.println();
}