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Austin Spivey for Wia

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Setup an Espressif ESP8266 and Publish an Event to Wia

Connecting to the Board

Note:If your board has a micro USB port (as with the NodeMCU breakout boards), you can skip this step, and go to the "Setup Your Environment" section below.

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

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ESP8266 Pinout

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 (Integrated development environment). This is where you can download it for Mac OS X, Windows and Linux here.

Detailed instructions can be found below:

Note: New to the Arduino IDE?
If you are completely unfamiliar with the Arduino IDE, watch this video [here]( to give you a better understanding of how it works.

  • Start the Arduino application and open Preferences
  • Enter into the Additional Board Manager URLs. If you need more than one, they can be separated with commas

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Install the ESP8266 Arduino package

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

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  • Select your ESP8266 board type by going to Tools > Board, then choosing your type. For this example, you can use NodeMCU 1.0 (ESP-12E Module)
  • Check that Upload Speed is set to 115200
  • Select the correct port for the board

Note: When selecting a port

For the ESP 8266, the port names tend to have unusual names, e.g:
On Mac OS: /dev/tty.usb.modem8232 or /dev/cu.SLAB_USB_toUART
On Windows: Com4 or Com3
On Linux /dev/ttyUSB0 or /dev/ttyACM0

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USB to UART Drivers Required

If your port is not showing up, you need to install USB to UART Bridge VCP drivers. To do so, go here, then download and install the drivers for your operating system. After installing the drivers, restart the Arduino IDE.

Note for Mac users

You may need to install the driver twice for it to work, as the first install will just remove the existing driver.

Charge-only USB cables

Another cause of the port not showing up could be the USB cable - make sure that the cable you're using is not a charge-only cable, and that it isn't faulty.

Create the Sketch

Measuring soil moisture with the NodeMCU Amica

If you came from our 'measuring soil moisture' tutorial, continue with that tutorial here. Otherwise, please continue with the tutorial below.

  • Click on File > New to create a new Sketch
  • Copy and paste the publish event example code below. You can also view it on GitHub here. In that directly you will see how to publish both Events and Locations


 * PublishEvent.ino
 *  Created on: 09.01.2017

#include <Arduino.h>

#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>

#include <ESP8266HTTPClient.h>

#define USE_SERIAL Serial

ESP8266WiFiMulti WiFiMulti;

const char* ssid     = "your-ssid";
const char* password = "your-password";

// get this from the wia dashboard. it should start with `d_sk`
const char* device_secret_key = "your-device-secret-key";

void setup() {

    WiFiMulti.addAP(ssid, password);

void loop() {
    // wait for WiFi connection
    if(( == WL_CONNECTED)) {
        HTTPClient http;

        USE_SERIAL.print("[HTTP] begin...\n");

        // configure wia rest api

        USE_SERIAL.print("[HTTP] POST...\n");

        // set authorization token
        http.addHeader("Authorization", "Bearer " + String(device_secret_key));

        // set content-type to json
        http.addHeader("Content-Type", "application/json");

        // start connection and send HTTP headers. replace name and data values with your own.
        int httpCode = http.POST("{\"name\":\"temperature\",\"data\":21.5}");

        // httpCode will be negative on error
        if(httpCode > 0) {
            // HTTP header has been send and Server response header has been handled
            USE_SERIAL.printf("[HTTP] POST... code: %d\n", httpCode);

            // file found at server
            if(httpCode == HTTP_CODE_OK) {
                String payload = http.getString();
        } else {
            USE_SERIAL.printf("[HTTP] POST... failed, error: %s\n", http.errorToString(httpCode).c_str());


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Replace the values of the following variables:

  • ssid - with your WiFi network name.
  • password - with your WiFi network password.
  • device_secret_key with your device secret key from the Wia Dashboard (the one that begins with d_sk).
  • Go to Sketch > Upload to send it to your ESP8266. Now go to your device in the Wia dashboard and you should see the data appearing in the debugger.

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Wia Device Debugger

Common errors

If you encounter an error like the one denoted in the image below, check if your board and port are correctly set in the Tools menu.

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Board or Port Failure

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