I'll document here progress on my POV project. The aim is to show some text on a bank of LEDs connected to Bifferboard, with the bifferboard spinning round, battery operated and controlled over either wifi or bluetooth.
First off I needed some LEDs. I created a module to connect to J1, the maximum number of LEDs I can get this way without external silicon being 6 (4 JTAG + serial TX and RX).
The cathode of each LED is connected to a GPIO pin which pulls it low to switch on. The anode goes via 330 Ohm current-limiting resistor to +3.3v. The precise resistor required will depend on your LEDs. The ones below were stolen from a faulty ethernet hub, so there are two banks but the top LED isn't used!
For now, the simplest way to control the LEDs is to use TCC (Tiny C Compiler), TCC has a very handy 'C-script' mode where you can use it as a script parser for C programs. Since inline assembler instructions are also supported, we can even output to GPIO ports in the script. The attachments below show a travelling light demo (source code and video) which is fairly pointless, but indicates how I might control the LEDs.
How to setup the software