Thingspeak: Ethernet

/*
  WriteMultipleFields
  
  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. !!!
  
  Note:
 - Requires the Ethernet library
  
  ThingSpeak ( https://www.thingspeak.com ) is an analytic IoT platform service
  that allows you to  aggregate, visualize, and 
  analyze live data streams in the cloud.
  Visit https://www.thingspeak.com to sign up for a free account and create a channel.  
 
  Documentation for the ThingSpeak Communication Library for Arduino
  is in the README.md folder where the library was installed.
  See https://www.mathworks.com/help/thingspeak/index.html 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 ");
    Serial.println(Ethernet.localIP());
  }
  // give the Ethernet shield a second to initialize:
  delay(1000);

  dht.begin();  
  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!");
     return;
  }
  
  // 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.");
  }
  else{
    Serial.println("Problem updating channel. HTTP error code " + String(x));
  }
     
  delay(20000); // Wait 20 seconds to update the channel again
}

secret.h

/ 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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• Arduino