NodeMCU, Mengirim Data Sensor LDR ke Thingspek

Mari kita belajar lagi, kali ini membahas sensor LDR. Dimana sensor ini nilainya akan berubah menyesuaikan cahaya yang diterima oleh sensor. Semakin banyak cahaya yang diterima, semakin bertambah nilai resistansinya dan sebaliknya. Nah data yang didapat akan kita kirim ke thingspeak. Berikut ini cara lengkapnya.

Alat dan bahan :

Nodemcu CH340/amica, BELI
Sensor LDR, BELI
Kabel Jumper, BELI
Projectbord, BELI
Resistor 10K ohm, BELI

Rangkaian

Keterangan :

Pemasangan kaki sensor ldr boleh terbalik
Kaki 1 dihubungkan ke 3.3v
kaki 2 ke pin A0 dan resistor 10K dan GND

Untuk terhubung ke thingspeak, silahkan login terlebih dahulu ke thingspeak.com.

Buat Channel baru > nama field harus sama dengan nama field di sketch program arduino.
Masuk ke menu API Keys copy write api ke sketch program
pada program berikut :
```
String apiKey = "9ME1X3TME6O1EDRI";
```

Sketch Program

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>

const char *ssid = "xxxxxxx";  //nama wifi
const char *password = "xxxxxxxx"; //password wifi

const char *host = "api.thingspeak.com";
String apiKey = "9ME1X389jkDRI";  //ENTER YOUR API KEY <<<<<<<<<<<

void setup() {
  delay(1000);
  Serial.begin(115200);

  WiFi.mode(WIFI_STA);        //This line hides the viewing of ESP as wifi hotspot

  WiFi.begin(ssid, password);     //Connect to your WiFi router
  Serial.println("");

  Serial.print("Connecting");
  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());  //IP address assigned to your ESP
}

void loop() {
  WiFiClient client;
  const int httpPort = 80; //Port 80 is commonly used for www

  if (!client.connect(host, httpPort)) {
    Serial.println("Connection Failed");
    delay(300);
    return; //Keep retrying until we get connected
  }

  String ldr;
  int adcvalue = analogRead(A0); //Read Analog value of LDR
  ldr = String(adcvalue);   //String to interger conversion
  String Link = "GET /update?api_key=" + apiKey + "&field1="; //Requeste webpage
  Link = Link + ldr;
  Link = Link + " HTTP/1.1\r\n" + "Host: " + host + "\r\n" + "Connection: close\r\n\r\n";
  client.print(Link);
  delay(100);

  int timeout = 0;
  while ((!client.available()) && (timeout < 1000)) {
    delay(10);  //Use this with time out
    timeout++;
  }

  if (timeout < 500) {
    while (client.available()) {
      Serial.println(client.readString()); //Response from ThingSpeak
    }
  }
  else {
    Serial.println("Request timeout..");
  }

  delay(5000);  //Read Web Page every 5 seconds
}

Upload sketch program di atas
Board : NodeMCU 1.0
Port : terceklis

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