Arduino กับ Nodejs

#include <DHT.h> //เรียกใช้ library DHT.h
#define DHTPIN 14 // เลือกขา GPIO14
#define DHTTYPE DHT22 // DHT 22 (AM2302)
DHT dht(DHTPIN, DHTTYPE, 15);

void setup() {
 Serial.begin(9600);
 dht.begin(); //เริ่มเรียกการใช้งาน dht จาก library
}

void sendJsonString(float temperature, float humidity, String dataStatus, String reason){
  /*
  {
    "data" : {
      "temperature" : 0.0, // 0,NaN
      "humidity" : 0.0 
    }, 
    "status" : "OK", //OK, Error
    "reason" : ""
  }
  */
  String s = "";
  s += String("{");
  s += String("\"data\" : {"); 
  s += String("\"temperature\" : " + String(temperature) + "," );
  s += String("\"humidity\" : " + String(humidity) );
  s += String("} ," ); 
  s += String("\"status\" : \"" + dataStatus + "\"" + "," );
  s += String("\"reason\" : \"" + error + "\"");
  s += String("}");
  Serial.println(s); 
}

void loop() {
  // Reading temperature or humidity takes about 250 milliseconds!
  delayMicroseconds(250);
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  delay(2000);
  // Set up data
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  // check if returns are valid, if they are NaN (not a number) then something went wrong! 
  float temperature = t;
  float humidity = h; 
  String dataStatus = "OK";
  String reason = "";
  if (isnan(t) || isnan(h)) {
    temperature = 0;
    humidity = 0; 
    dataStatus = "Error";
    reason = "Failed to read from DHT";
  }
  // Send data
  sendJsonString(temperature, humidity, dataStatus, reason);