Wire Wrap Introduction Video

This post is to provide a link to my new video on YouTube and a bit more accompanying explanation.

First off, here is the video:


For those who are curious about some further explanation of the process and purchasing wire wrap supplies, I see that Jameco has a great online article and carries the supplies.(Check it out here). Wikipedia also has a great article on wire wrapping here.

I recall working for a company in the 1990s that was still using it extensively for building aircraft maintenance simulators because it is reliable, quick and easy and well suited to very small production run products. Early computers used the technique extensively. Check out this picture of a Z80 backplane from 1977:

The main challenge is obviously keeping track of the many point-to-point connections when you are looking at the back of the board! I seem to recall the firm I worked for had some sort of system of tables for keeping track of what went from where to where. Generally, I find that if I am going to have problems with a wire wrap assembly, it will be an error I have made in losing track of which pin is which when I flip the board over!

That's it for now! Soon I will do a longer post on my first work with the nRF24L01 radios and my DigiX board. I have something almost working and when it's done I will provide more details.

RFID Facebook Updater

I have an RFID reader I bought from www.sparkfun.com and 5 credit card style RFID cards. The reader is hooked up to my Gumstix small PC via serial.

I have two PHP scripts running on the Gumstix. One continuously monitors the RFID reader to see if there has been a card read and it writes that value to a file. The other script is the actual Facebook application that picks up the RFID tag value and lines it up with statuses I have assigned the different cards.

Anyway, very cool to learn how to use RFID and write a very simple Facebook application. In a broader application, this does show that you can "hardware-enable" Facebook so that you could have statuses, new stories, messages generated by a variety of different "real-world" events. This could be a home alarm system or just your plants saying they need to be watered.

While it is possible to generate these kinds of messages through other means (email, SMS etc), Facebook offers a reasonably comprehensive framework for authentication & messaging and a more-or-less documented API.

Here is a shot of the updater & my Gumstix:


And here is a diagram:


I have pretty much stopped work on this as my Arduino-based stuff has come back to the fore front. Some of the things I would like to do with this are:

• Have the status messages stored in a SQL database so they can be updated more easily (currently they are hardcoded into the PHP script for the FB application).
• Have a "remote reader" with an Arduino & an Xbee radio so your status can be updated anywhere in the house.
• Think about how to scale this up so multiple people could use the application. How would it be hosted, how to architect the reader (Arduino with Xport Ethernet, maybe?). Would there be a demand for a Facebook "hardware add-on"?