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    douma rahma

    @douma rahma

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    Best posts made by douma rahma

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    Latest posts made by douma rahma

    • RE: MH-Z19 with Arduino R3 0 outputValue

      @Ed1500 I am connecting the Arduino via USB port

      posted in Development
      douma rahma
      douma rahma
    • RE: MH-Z19 with Arduino R3 0 outputValue

      @Ed1500 Thank you for your response I will try it. Are you using PWM or not?

      posted in Development
      douma rahma
      douma rahma
    • MH-Z19 with Arduino R3 0 outputValue

      Hi,
      I am using this code to get C02 value. But always I get this result (CRC 0/0) even after waiting more than 3 min for the healing process.

      #include <SoftwareSerial.h>;
      
      SoftwareSerial mySerial(A0, A1); // A0 - к TX сенсора, A1 - к RX
      
      byte cmd[9] = {0xFF,0x01,0x86,0x00,0x00,0x00,0x00,0x00,0x79}; 
      unsigned char response[9];
      
      void setup() {
        Serial.begin(9600);
        mySerial.begin(9600);
      }
      
      void loop() 
      {
        mySerial.write(cmd, 9);
        memset(response, 0, 9);
        mySerial.readBytes(response, 9);
        int i;
        byte crc = 0;
        for (i = 1; i < 8; i++) crc+=response[i];
        crc = 255 - crc;
        crc++;
      
        if ( !(response[0] == 0xFF && response[1] == 0x86 && response[8] == crc) ) {
          Serial.println("CRC error: " + String(crc) + " / "+ String(response[8]));
        } else {
          unsigned int responseHigh = (unsigned int) response[2];
          unsigned int responseLow = (unsigned int) response[3];
          unsigned int ppm = (256*responseHigh) + responseLow;
          Serial.println(ppm);
        }
        delay(10000);
      }
      

      I used the sensor directly without any calibration. Another note, why I can only use 3.3V, the 5v make my Arduino card shutdown

      posted in Development
      douma rahma
      douma rahma