Velleman K8000 - [K8000 Standalone Usage] - [K8000 Wireless Server]

K8000 Server

Introduction to the K8000 server

Sometimes people are asking me if it is possible to control the K8000 over a wireless connection. Sure this is possible. In fact there are several possibilities to do this.

The K8000 card is using the I2C protocol to receive commands from a master. The I2C protocol is a 2-wire protocol that was originally designed to communicate between chips on an electronic circuit. You could create a wireless communication by making a transmitter to send/receive I2C commands. But it would be hard to implement and I2C was not designed for such purposes anyway.

Instead it is better to add a controller to the K8000: This controller will handle all the I2C communications with the K8000. The controller will also handle the wireless communications. This wireless communication doesn't have to use the I2C protocol: the controller will act as a translater between I2C and any other protocol.

diagram of the wireless controller

The easy solution: FEZ Panda II and (Wi-Fi) Ethernet

This kind of project can be made with a regular microcontroller, like a PIC. But I have chosen to use the FEZ Panda II board as the controller. The reasons are obvious: I already have a lot of experience with the combination Fez Panda II / K8000 card and the FEZ is very flexible.

The Fez Panda II doesn't have a wireless module but it has something even better: a wired Ethernet connection. It can be easily turned into a wireless device (Wi-Fi) by plugging this ethernet connection into a wireless brige (Wi-Fi to Ethernet).

There are many advantages in doing so. First of all Wi-Fi is reliable and it provides encrypted communications (by using a WEP or WPA key).

The following image gives you an idea of the complete system I worked out. At the left you see a computer that is connected to a wireless Wi-Fi network. Then there is the FEZ which is connected to a wireless access point (ethernet-to-wifi bridge). The FEZ is also connected to the K8000.

setup for the wireless transmission

Building a wireless application: the requirements

So we just decided to proceed on with the K8000 / Fez Panda II / WiFI solution. You might wonder: what do I need to make? It all depends on the type of solution you want to make. I have chosen to write a TCP/IP server that runs on the FEZ Panda II. This server will accept incoming TCP/IP connections from a remote client. We need to to the following things before we can make it work:

First of all we need to design a communication protocol. I already indicated I wanted to use a TCP/IP server. So the network protocol is TCP/IP. This protocol will transmit packets with data/text. This data/text should also follow a certain protocol: it is this protocol we need to design.
Secondly we need to write a server application that runs on the FEZ Panda II. The server application will listen for connection requests on a certain TCP/IP port. It should accept any connection requests and then start a text-based communication: this means the server has to accept text commands containing instructions. Then these instructions will be translated to K8000 commands. These are executed on the K8000 card, trough the I2C bus.
Thirdly we need to write a client application. This application will run on our computer. It must be capable to establish a TCP/IP connection with the remote TCP/IP server. Once the connection is made it can start to send/receive commands to the K8000 card.

All this might sound complicated but we need to split the project into pieces. Then we need to work out piece by piece: we have a client part, a server part, and a protocol for the communications between them.

diagram of the client/server model

Project contents: the pieces

Here you can find the different pages for all parts of the project: