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NerdKits has put together a video that describes how a LED row/column matrix is wired. This comes in handy when you have limited pins and need to control lots of items. Another popular method is to use a serial to parallel latch.
"This project makes use of row-column addressing, which lets us control lots of LEDs without having one wire going to each one. We also use one more trick — the fact that diodes only conduct in one direction — to double the number of LEDs you can handle with the ATmega168 microcontroller. " |
January 23rd, 2009
[...] Fuente - Hackedgadgets [...]
January 23rd, 2009
Always informative! LED is the future of lighting.
January 23rd, 2009
By switching the polarity and driving the led with a backward current you will destroy them in the near future.
better way is to adress the rows and colums by multiplexer ics.
January 23rd, 2009
It is actually safe Chris LEDs have a reverse voltage range, as long as the reverse biased voltage is within that range you will be fine. It is usually in the 5 or 6 volt range. There are actually 2 lead LEDs that have two internal LEDs and depending on which one is forward biased it will light and the other will not conduct and stay dark.
http://www.scienceprog.com/bi-color-led-indication/
January 26th, 2009
Not to be mean but invented? AFAIK this is known as charlieplexing and is nothing new!
I don’t mean to be rude, but misinformation is something I dislike =)
November 10th, 2009
[...] are lots of Nerd Kits project examples available. Josh Davis used the LED Array Sign project and added a cool option for the sign to display voice messages left with the help of a Google voice [...]