Jump to content

Digital number display using doors and logic gates


Recommended Posts

Why you might ask? Well... why not? 

This contraption takes a 4 bit binary input and outputs digits 0-9 and A-F. Technically it is a BCD (binary coded decimal) to 7 Segment Display Decoder.

It took about 3 hours to lay out and 1 hour to debug an issue with one of the outputs.

Video of it in action: 

https://www.youtube.com/watch?v=Uh1YJqF51D4

 

 

hex-display.png

Link to comment
Share on other sites

I was in the process of making one myself before you posting the video. This one is entirely error checked though so no missing bits. I also shrank it quite a lot (I think) as miniaturizing is something I enjoy.

Inputs are top left in the natural MSB first order.

Outputs are top right in a to g descending order.

The display can be made of ceiling lights too if speed is problem as doors are quite slow.

Save file included.

7segment display.sav

2017-11-04 (2).png

2017-11-04 (1).png

Link to comment
Share on other sites

5 minutes ago, GrindThisGame said:

Super compact ! I love it. I was worried I would run out of space with the jumble of wires so I left some room. How does the error checking part work? It's like sending data over a noisy channel :p

Nah. I mean I error checked it. So every number is displayed correctly. Note though that I use small letters so it 1-9 then a, b, c, d, e, f instead of a mix of capital letters and small letters.

Link to comment
Share on other sites

7 minutes ago, GrindThisGame said:

Had you built one of these before? Did you find this design or just derive it? When looking I'm seeing much more compact designs out there.

Have you seen the video of a video player made inside factorio? Some crazy stuff out there.

I started doing it by memory and note paper but it took too long so I used logism which is a free educational tool for testing and designing logic circuits. So yeah, I made it from scratch.

http://www.cburch.com/logisim/

Link to comment
Share on other sites

3 minutes ago, GrindThisGame said:

This one looks very compact (but only 1-9):

https://quickgrid.wordpress.com/2015/03/22/7-segment-decoder-implementation-truth-table-logisim-diagram/

Yeah I didn't want to spend my weekend with k-maps. It's been 20 years since I did some comp sci.

Problem is that a hexadecimal display logic table is about 3 times more complicated than a decimal one so there's no way to make it smaller than what I did. Except for a few tiles. 

Link to comment
Share on other sites

17 hours ago, GrindThisGame said:

This one looks very compact (but only 1-9):

https://quickgrid.wordpress.com/2015/03/22/7-segment-decoder-implementation-truth-table-logisim-diagram/

Yeah I didn't want to spend my weekend with k-maps. It's been 20 years since I did some comp sci.

 

In the page you linked, the logic function for the 0 segment is given and can be simplified a tiny bit while using a nxor. The screens showing the results of Logism doesn't seem to use xor gates, so it's probably possible to win something there. Also the not are put at the leaf but could sometimes be moved a bit deeper in the tree to reduce the number of not gates.

Link to comment
Share on other sites

I've compacted it a bit more and as @Cilya mentioned I probably could have used XOR to simplify a few functions but I'm not going to spend more time on chasing single digit tile improvements,

Here is my latest effort. In case you're wondering, it's 33x46 tiles. It was 43x47 tiles before so a 33% area reduction. And remember, it can be hidden behind regualr tiles or in a water tank. (Save file included).

EDIT: Discovered an error. Make the connection indicated by the blue line in the blue circle.

compact 7seg.sav

2017-11-05 (1).png

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Please be aware that the content of this thread may be outdated and no longer applicable.

×
  • Create New...