Hacked Gadgets Forum

October 18, 2007

LED Hat

at 5:11 am. Filed under Complex Hacks, Cool Gadgets, DIY Hacks, Electronic Hacks

You might not have enough time to build this LED Hat in time for Halloween this year but if you start now you should be finished by next year! It is hard to understand the complexity of this project without thinking about how it works for a few moments…

“Okay, so I bought an AVR STK500 programmer board for about £80 from http://uk.farnell.com, which comes with an ATmega16 and an ATmega8515-8PC microcontroller (not an AT90S8515-8PC as stated in the manual, but I only figured this out later). Just to be extravagant, I also bought an ATmega128, which has 64 pins so I had to buy an STK501, which costs more than the STK500 (about £95). This was from http://rswww.com; it hasn’t arrived yet, however.

It needs a serial RS232 port (AKA a COM port on PCs) to program it. These are a bit rare these days, so I thought I was going to have to buy a USB to RS232 adapter, which cost about £30, and seem hard to find in shops. If I did buy one, I’d want it also to work on Linux, and operate at the required 11280+ baud. Luckily however, I discovered that I do have a COM port on a windows box I have.

My friend (Martin) suggested that I might use a chain of shift-registers to shift out a given pattern to the LEDs quickly, pause for a while, then repeat. If this is done quickly enough, the shifting should be invisible. Presumably some sort of arrangement with latches could keep the LEDs isolated whilst the shifting happens if this proves to be a problem.”