7 LED’s, 2 Pins – beat that, Charlieplexing

[Tim]’s Cube10 is an train in minimalism. Constructing an digital cube utilizing an ATtiny10 with code that matches inside 1kB isn’t too troublesome. Charlieplexing the LED’s would have used three of the 4 out there GPIO pins. [Tim] upped the sport by utilizing simply two GPIO pins to drive the seven LED’s for the cube. A 3rd GPIO is used as a contact button enter. In addition to the ATtiny and the LED’s, the one different element used is a capacitor throughout the provision inputs.

2 GPIO for 7 LED's  7 LED’s, 2 Pins – beat that, Charlieplexing dice10 01
2 GPIO for 7 LED’s

The LED’s are grouped in three pairs of two LED’s and a single centre LED. Often, Charlieplexed LED’s are related throughout pairs of GPIO pins. However his scheme contains connections to the 5V and GND terminals, apart from the 2 GPIO pins. Constructing a fact desk makes it simple to determine what’s occurring.

1     Z   Z   --
2     L   Z   LED half
three     H   Z   LED three/four
four     Z   L   LED 5/6
5     Z   H   --
6     H   L   LED9
7     L   H   --
eight     H   H   --
9     L   L   --

Solely the logic states used are listed within the desk. It’s potential so as to add two extra LED’s between PB0 and GND and another anti-parallel with LED9, making a complete of 10 LED’s pushed by two pins. That’s fairly a hack. The essential factor right here is to have two LED’s in sequence within the arms that connect with both 5V or GND.

[Tim] has posted  the code and supply recordsdata on his Github repo, and his weblog publish has some extra particulars on how he solved the issue.

If you happen to’re on the lookout for extra inspirations on minimal cube designs, examine this “PIC powered pair of digital cube” which makes use of a PIC 12F629 with 5 outputs driving a pair of seven pips to make a twin cube.

1kb-thumb  7 LED’s, 2 Pins – beat that, Charlieplexing 1kb thumb

In case you have a cool undertaking in thoughts, there may be nonetheless loads of time to enter the 1 kB Problem! Deadline is January 5, so test it out and fireplace up your assemblers!

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