Attiny 85 Decade Counter

Get a reading from your decade counter with i2c!

John Spencer

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Description

Decade counters come with an 11 pin interface. One pin per value and a common ground. This seemed like a horrible waste and surely there is a way to make it easier and more useful to use.

Details

Replacing the circuit board with a custom one wasn't a hugely difficult process. 603 SMD components were mainly used to keep the size down to fit in such a limited space.

The position the dial is at is dictated by a resistance wheel. Each segment adds 220Ohms of resistance and checking this value using the internal voltage of the chip gives sufficient deviation to identify each position.

The WS2812b is included on the board and if the central dial is translucent the dial will glow.

Components

1 × http://www.adafruit.com/products/1082 Adafruit Mechanical Decade Counter
1 × Attiny 85
1 × WS2812b
9 × 220 Ohm 603 resistors
1 × 0.1uf 603 capacitor

Project Logs

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Wouldn't be one of my projects with something going wrong
John Spencer • 06/07/2014 at 05:46 • 0 comments

I had originally intended for the glow from the LED to reflect around the dial, unfortunately this was not the case.
3D printing a replacement dial shouldn't prove too much of a difficulty though.