A simple example of building a HTML based UI for a ESP8266 powered device. This is based on programming the ESP8266 with the Arduino IDE.

The Arduino sketch lets you control a LED attached to your ESP8266 board via WiFi and a HTML user interface.

These files are meant to be used with the Arduino IDE and the ESP8266 core. At the time of writing Arduino 1.6.7 was used with the most recent git checkout of the ESP8266 core due to some problems regarding the stable version. This might change soon as things stabilize.

Open htmlled.ino in the Arduino IDE. Select the ESP8266 board you're using and flash the sketch.

index.html (and any other files) must be compiled into a SPIFFS filesystem and uploaded to the board. There's good documentation on the subject. For small projects it makes sense to choose the 1M SPIFFS size (or smaller if available) to avoid unnecessarily long upload times.

When the sketch is up and running on the board, you should be able to connect to the access point using any WiFi enabled device. Navigate to 192.168.4.1 and you should see the control UI.

The sketch was tested on a WeMos Mini D1.

I've been toying with the idea of a standalone ESP8266-based robot which would be controlled via a mobile phone browser over WiFi. In the Arduino world it seems that Bluetooth is a more traditional means of controlling such appliances. However, in principle, one needs to write a specialised mobile app to have a nice control interface. It also means the app won't be cross-platform.

I don't know mobile app development well. What I know better is JavaScript and HTML. So I set out to have the ESP8266 act as a WiFi access point (and hence not depend on any existing WiFi network) and serve its own control UI to the phone browser. Neat, isn't it?

While there's a wealth of ESP8266 examples around, I didn't find an application exactly like mine by a quick glance. This wasn't hard to implement, but there are some pitfalls. Hence I've shared this example with you.

My requirements for this system were:

• Be standalone. The device mustn't depend on any existing network.
• No unnecessary page loads -- implement user interaction with AJAX calls.
• HTML and JS files stored in the SPIFFS for scalability and convenient development. In most of the examples the HTML files were "baked in" the source code which is cumbersome to maintain.
• Two-way communication between client and the device.

While this is meant to be a simplistic example, there's always room for improvement. Pull requests are appreciated.

There are some items I intend to tackle soon:

• Diagnostic information over serial
• Seamless support for serving multiple files (such as CSS, JS and images)
• Utilize captive portal to open the UI immediately upon connecting?