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Clockless serial to parallel interface options???......

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I have a widget with a single data output line that I need to use as the input to a serial to parallel converter.  This would be trivial with a simple shift register, but I don't have any extra data lines to use for clock and OE.

I need to "upgrade" this existing design that I cannot change so I'm stuck with that single data line.

Other requirements:
1) I only actually need 4bits parallel output.
2) Data rate on the serial input does not need to be crazy fast.  No need for Mbps here.  If I could change the parallel output at about 1kHz or faster, that would be fine.
3) Normal 3.3V - 5V supply ranges.
4) Not a microcontroller.  Besides the digital design purist aspect of a micro here should not be necessary, it's also a production step I don't want.
5) Pretty much any serial data format is acceptable.  I can tweak the firmware on the widget to output what I need.  I just can't change the hardware interface from the single data line.

It's hard to search for this since most serial to parallel shift registers are clocked and that's never used as a parameter in the parametric search. 

I've so far found the SN74LV8153, which looks like it will work fine.  But it's a little expensive, and I don't need 8 bits of parallel output so having to send it two packets for a total of 16bits is unnecessary.  The addressing is also unnecessary since I'll only be using one of these.

Are there any other clockless serial to parallel interfaces that you guys can think of?  Preferably 4 bits?

Standard since decades.
You can choose between 7- and 8-bit transfers.


--- Quote from: Benta on June 14, 2024, 09:59:55 pm ---RS-232.
Standard since decades.
You can choose between 7- and 8-bit transfers.

--- End quote ---

Part numbers?
I looked at "uart to parallel" and "RS232 to parallel" and didn't see anything reasonable in IC form.

You're right. The old standard UARTs don't seem to exist any more.

Another option is Manchester coding, which is self-clocking. However, you'll need to think about some kind of start/stop frame timing, which needs additional logic. A small 14-pin, 50-cent MCU would really be the best solution. I know of no off-the-shelf parts.

I'm pretty sure SN74LV8153 does the job here.  If that's all that there is, I can live with the down sides I mentioned above. 

Hell, even a tiny 8 pin micro with minimal memory should do what I'm looking to do here.  But not having a firmware programming/testing step in production is a big enough deal that I'm going to explore the pure hardware first.


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