Category Archives: Electronics

Hacking La Fonera – part 1

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FoneraI bought a small La Fonera router for €7,5 a couple of weeks ago, just for the fun of replacing the firmware and tinker with a personalised Linux kernel and filesystem. I also installed a brand new web interface on it.

In the attached file you can find the details on how I replaced the bootloaders configuration, the Linux kernel and the filesystem:
Hacking La Fonera (Open Office document, download Open Office here)

I’m still working on building an RS232 level converter module for the internal serial interface on the router, and I’m trying to figure out the iptables firewall configuration so I can do NAT translation of the LAN side when I set the router as a wireless client.

Just trying to get a feel for it, really. Afterwards I’m thinking of installing a build environment on my PC and I’ll try to build the OpenWRT kernel and filesystem myself. I’m not sure whether there is a cross-toolchain for this I can just download or whether I need to create one myself? Creating a cross-toolchain from scratch is a bit of a challenge, I’ve done it once before, but it does take a couple of days until you get all the versions right and get the thing to compile properly.

POV rotating LEDs not dead?

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The rotating LED idea is now 2 years old, and I haven’t got any further. A while ago I was sorting out the closet in my cubicle which I inherited when a colleague left. And I came across various boards and prototype devices from previous discontinued projects, like satellite locators with a large LCD display, 2-way satellite devices for Interactive TV, and stuff like that. All the way at the bottom of the junk pile, I found two development and evaluation boards. One for a PIC controller we still use in today’s products, and one for an ARM controller.

SMDK40100
The ARM board is an SMDK40100 development board from Aiji Systems used in the evaluation of the controller and the initial development done for the interactive TV modules. The entire product line has been discontinued for as far as I know, and that 40MHz microcontroller is in my closet gathering dust. Now I think that’s a real shame. There are even JTAG debuggers for that ARM processor in my closet, and no one in the company is developing for ARM any more. A real pity.

PICDEM 2 PLUS
The PIC board is a PICDEM 2 PLUS demo board from Microchip. It is fitted with a P18PTST and a small LCD screen.

So I’m gathering my courage to step over to my boss and ask him if I can liberate those boards and give them a new life as light show.

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Materials needed

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I know that the POV (persistance of vision) LED display has been on hold for quite a while, due to lack of interests of the friends who promised to help in the first place. I have still been thinking about doing this project all by myself instead, but I still need to have a few tools before I’ll be ready to start. One of those most crucial tools would be a multimeter. My previous one was stolen. Ok, I know that’s not a good ecxuse because it got stolen about 6 years ago, but well… :-)

One other tool I needed was an osciloscope. I was thinking that this tool would be quite hard to obtain for a reasonable price, but against all odds it was easier than the multimeter. Now I’m in possession of a dual channel, 100MHZ Philips scope. The device is really good, but I don’t understand all the options of the trigger circuit. One turn down: there were no test probes included with the second hand scope, so I still need to buy those.

Further I need to find a electronic engineering program that would allow me to design and simulate the schematic, without spending thousands of euros, I need test print boards to make the prototypes, I need the chips and components (plus reserve components to replace those that fizz or bang)… Lot’s of things before I can start making a mechanical design, and have a stable rotating LED display.

So you see, the project isn’t cancelled, only delayed :-)

POV rotating leds – Part 1

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A few friends and I have come up with the bold idea of doing something fun with the electronics skills we picked up at school, and we decided to make a rotating led display. This would be an array of leds, mounted perpendicoulous on a spinning rod, switching on and off very fast in a predefined pattern. Because of the slowness of the eye, the pattern of leds should remain clearly visible when it moves across the plane of sight, this phenomenon is know as persistence of vision (POV). This pattern can be anything from letters, words and sentences to entire pictures, depending on the size and complexity of the electronics.
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