One pin shift register interface

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#1
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This technique might be useful in some situations where you run out of pins:

romanblack.com/shift1.htm

It should work with an AVR.

Leon

Leon Heller G1HSM

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Thats kind of cool!

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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I've seen it taken even more extreme.

The one wire signal was not logic level, but regulated positive supply, coming from a LM317 regulator output, which can be controlled with GPIO pin (ADJ pin).

So the whole thing got it's power, clock, data and latch signals from single wiggling pin.

Of course the thing needed diode, reservoir cap and regulator in the other end too.

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An EDN Design Idea posting using similar method for receiving parallel data from a shift register.

Microcontroller inputs parallel data using one pin - Alternate non-pdf link

Stan

Last Edited: Wed. Oct 27, 2010 - 10:32 PM
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I can do this using no pins. The method is fairly limited, however. There are certain data sequences that can't be sent.

Four legs good, two legs bad, three legs stable.