In this tutorial, we'll go through setting up an ESP8266 board, and publish an event to Wia via our CoAP API.

Connecting the board

Note: If your board has a micro USB port, you can probably skip this step.

Connect your board to laptop/desktop via a USB to TTL cable/adapter. Here's a pinout showing the different connections.

Connections between the ESP and USB TTL are the following:

• ESP8266 <-> USB TTL
• GND <-> GND
• TX <-> RX
• VCC <-> 3.3V(+)
• CH_PD <-> 3.3V(+)
• GPIO0 <-> GND (Only while flashing the board)

Setup Your Environment

• Install the Arduino IDE. You can download it for Mac OS X, Windows and Linux here
• Start the Arduino application and open Preferences
• Enter http://arduino.esp8266.com/stable/package_esp8266com_index.json into the Additional Board Manager URLs. If you need more than one, they can be separated with commas

• Go to Tools > Board > Boards Manager
• Search for esp8266. When found, click Install

Select your ESP8266 board type by going to Tools > Board, then choosing your type. For this example I am using NodeMCU 1.0 (ESP-12E Module).

You can get the name of your device's port using one of the following steps:

Linux and Mac OS X

• Download and install the FTDI drivers from here. Select the appropriate version for your operating system and architecture
• Open a terminal window and run the command ls /dev/tty*
• Look for a device with the name that begins with /dev/tty e.g. /dev/tty.usbmodemPy343431 on MAC or /dev/ttyUSB0/dev/ttyACM0 on Linux

Note:
For Linux, you may need to run the two commands below. Once you've completed that, reboot your computer. This will add permissions that will allow you to upload a sketch to the board.

sudo usermod -a -G tty ${USER}
sudo usermod -a -G dialout ${USER}

Windows

• Download and install the FTDI drivers from here. Select the appropriate version for your operating system and architecture
• Open the Windows start menu and search for Device Manager
• The COM port for the ESP8266 device will be listed as USB Serial Device or something similar
  • Keep note of the COM port (e.g. COM4)

Install the required libraries

In the Arduino IDE, Go to Sketch > Include Libraries > Manage Libraries. Install each of the following libraries by searching for their name in the search bar within the modal. A button will appear in the bottom right of the box that will allow you to install the library.

• ESP8266WiFi
• ArduinoJson

ADDING COAP LIBRARY

To add the CoAP client library, you must manually add it to the libraries folder in your Arduino root folder.

• Download the zip file here
• Find the location of the Arduino folder on your operating system
• In the Arduino folder, click into libraries sub folder
• Extract the zip file
• Restart the Arduino IDE

Add a Device in Wia

If you haven't already, you'll need create a Device in your Wia account. Tutorials can be found here.

Create the Sketch

In the Arduino IDE:

• Click on File > New to create a new Sketch
• Copy and paste the example code below publishes an Event via CoAP
• The callback contains a placeholder section to write code to do something useful when a Command has been triggered ```

include

include

include "coap_client.h"

//instance for coapclient
coapClient coap;

//WiFi connection info
const char* ssid = "your-wifi-ssid";
const char* password = "your-wifi-password";
String DEVICE_SECRET_KEY = "your-device_secret_key";

//ip address and default port of coap server in which your interested in
IPAddress ip(52, 17, 209, 228);
int port = 5683;
char* path = "events";

StaticJsonBuffer<200> jsonBuffer;
JsonObject& root = jsonBuffer.createObject();

// coap client response callback
void callback_response(coapPacket &packet, IPAddress ip, int port) {
char p[packet.payloadlen + 1];
memcpy(p, packet.payload, packet.payloadlen);
p[packet.payloadlen] = NULL;

//response from coap server
if (packet.type == 3 && packet.code == 0) {
Serial.println("ping ok");
}

Serial.println(p);
}

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

WiFi.begin(ssid, password);
Serial.println(" ");

// Connection info to WiFi network
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
yield();
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
// Print the IP address of client
Serial.println(WiFi.localIP());

// client response callback.
// this endpoint is single callback.
coap.response(callback_response);

// start coap client
coap.start();
}

void loop() {
root["name"] = "temperature";
root["data"] = 21.5;
root["accessToken"] = DEVICE_SECRET_KEY;

String data;
root.printTo(data);
char dataChar[data.length() + 1];
data.toCharArray(dataChar, data.length() + 1);
bool state;

//post request
//arguments server ip address,default port,resource name, payload,payloadlength
int msgid = coap.post(ip, port, path, dataChar, data.length());

state = coap.loop();

delay(5000);
}

Replace the following values of the following variables:
* `your-wifi-ssid` - with your WiFi network name
* `your-wifi-password` - with your WiFi network password
* `your-device_secret_key` with your Device secret key from the Wia Dashboard (the one that begins with d_sk)
* Go to `Sketch > Upload` in the Arduino IDE menu to send it to your ESP8266
* Open your Serial Monitor to view the output from your ESP8266 by going to `Tools > Serial Monitor`

Now go to your device in the Wia dashboard and you should see the data appearing in the debugger. 

![alt text](https://files.readme.io/4fed030-Debugger_Wia.png)