WebCell Overview

You can skip the technical details and learn how to use the WebCell for home automation.

The WebCell embedded web server module

The WebCell is a full-feature yet low-cost web server module in just 3 square inches. The web server module includes an Ethernet jack for direct connection to the network and a microSD card socket for up to 32 GB of file storage. It has 21 I/O pins which can be used in various combinations for analog input and output; serial, SPI, and I2C communications; PWM; and general-purpose I/O.

Using a web interface on a control system allows it to have a sophisticated yet simple user interface. And wireless control with a handheld device comes virtually for free – there’s no need to develop an app for each platform (iPhone, Android, …) since smartphones and tablets support web browsing.

The WebCell can serve up static web content from the microSD card, but it can also generate dynamic web content through server-side script embedded in the web page. The scripting language is a subset of JavaScript called CellScript. CellScript provides full control over the I/O pins and access to the file system. It allows you to insert text or values into a web page or generate some or all of the web page programmatically. It also provides easy access to any data submitted back to the WebCell through a web form.

The WebCell is oriented toward home automation applications and includes a sophisticated scheduler. The scheduler supports single events or recurring schedules on a daily, weekly, monthly, or yearly basis. It allows multiple schedules for a device and schedules can be grouped to be easily changed together (such as switching to the “vacation” schedule group). A set of home automation web pages are available as a free download for the INSTEON home automation system. The web pages provide very easy-to-use control of thermostats, irrigation, power, and lighting.

You control, program, and update the WebCell with the CellScript Simulator, a free Windows application. The CellScript Simulator provides a full simulation of the WebCell, turning your PC into a web server. It allows you to debug CellScript code with breakpoints and single-stepping, giving a full view of program variables and complete access to simulated I/O. The CellScript Simulator also allows you to view the WebCell file system and synchronize files between the WebCell and your PC over the network.

The WebCell is also available mounted on the Cell Development Kit for easy experimentation. The development kit is powered by USB to provide the required 3.3V for the WebCell. It includes a host of I/O devices, including pushbuttons, analog input, SPI and I2C devices,and RS-232 serial as well as a prototyping area.