Thingspeak: Ethernet

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  Description: Writes values to fields 1,2,3 and 4  in a single ThingSpeak update every 20 seconds.
  Hardware: Arduino Ethernet
  !!! IMPORTANT - Modify the secrets.h file for this project with your network connection and ThingSpeak channel details. !!!
 - Requires the Ethernet library
  ThingSpeak ( ) is an analytic IoT platform service
  that allows you to  aggregate, visualize, and 
  analyze live data streams in the cloud.
  Visit to sign up for a free account and create a channel.  
  Documentation for the ThingSpeak Communication Library for Arduino
  is in the folder where the library was installed.
  See for the full ThingSpeak documentation.
  For licensing information, see the accompanying license file.
  Copyright 2018, The MathWorks, Inc.
#include "ThingSpeak.h"
#include <Ethernet.h>
#include "secrets.h"
#include "DHT.h"
#define DHTPIN 2 // what digital pin we're connected to
// Uncomment whatever type you're using!
//#define DHTTYPE DHT11 // DHT 11
#define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321

byte mac[] = SECRET_MAC;

// Set the static IP address to use if the DHCP fails to assign
IPAddress ip(192, 168, 0, 177);
IPAddress myDns(192, 168, 0, 1);

EthernetClient client; 

unsigned long myChannelNumber = SECRET_CH_ID;
const char * myWriteAPIKey = SECRET_WRITE_APIKEY; 

// Initialize our values
int number1 = 0;
int number2 = random(0,100);
int number3 = random(0,100);
int number4 = random(0,100);

void setup() {
  Ethernet.init(10);  // Most Arduino Ethernet hardware
  Serial.begin(115200);  //Initialize serial
  // start the Ethernet connection:
  Serial.println("Initialize Ethernet with DHCP:");
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // Check for Ethernet hardware present
    if (Ethernet.hardwareStatus() == EthernetNoHardware) {
      Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
      while (true) {
        delay(1); // do nothing, no point running without Ethernet hardware
    if (Ethernet.linkStatus() == LinkOFF) {
      Serial.println("Ethernet cable is not connected.");
    // try to congifure using IP address instead of DHCP:
    Ethernet.begin(mac, ip, myDns);
  } else {
    Serial.print("  DHCP assigned IP ");
  // give the Ethernet shield a second to initialize:

  ThingSpeak.begin(client);  // Initialize ThingSpeak

void loop() {
  float h = dht.readHumidity();
  // Reading temperature or humidity takes about 250 milliseconds!
  float t = dht.readTemperature();
  // Read temperature as Celsius (the default)
  if (isnan(h) || isnan(t) ) {
     Serial.println("Failed to read from DHT sensor!");
  // set the fields with the values
  ThingSpeak.setField(1, t);
  ThingSpeak.setField(2, h);

  // write to the ThingSpeak channel 
  int x = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);
  if(x == 200){
    Serial.println("Channel update successful.");
    Serial.println("Problem updating channel. HTTP error code " + String(x));
  delay(20000); // Wait 20 seconds to update the channel again


/ Use this file to store all of the private credentials 
// and connection details 

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
#define SECRET_MAC {0x02, 0xCA, 0xFF, 0xEE, 0xBA, 0xBE}

#define SECRET_CH_ID 000000	   // replace 0000000 with your channel number
#define SECRET_WRITE_APIKEY "XYZ" // replace XYZ with your channel write API Key

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