This technique might be useful in some situations where you run out of pins:
It should work with an AVR.
Leon Heller G1HSM
Thats kind of cool!
Until Black Lives Matter, we do not have "All Lives Matter"!
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.
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
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.
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