Interface old telephonedial to the Badge at HackadayBerlin2023

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My entry for the small badge-hack of the Supercon Badge at the Hackaday Berlin 2023 event. ( I had - for totally other reasons - an old telephone dial with me, so I decided to attach it, and write software so it would display the number dialled.
"For extra credit" - I hadn't seen the badge before, I hadn't read any of the documentation, I did therefore not have any assembler or serial upload. Handcoded and binary edited. Old School.
The hardware was also based on finding a bit of cardboard, my pocket knife and some masking tape. (Well, I borrowed a solderiron to attach the wires.)

The badge is a slightly updated version of and was the namebadge of the conference.

The telephone dial is pure mechanical - two switches with a common ground. One switch closes if the dial is not at its rest point, the other switch pulses when the dial returns with one pulse per digit.

Electronically thus the 3 wires were soldered to the IO connector such as the common wire was grounded by an output port bit 3 and the two switched wires were to input ports bit 0 and 1, just adjacent.

The real hardware challenge was the "case". Solved by finding a cardboard piece and a roll of masking tape. I had a sharp knife to cut holes and pieces, including stiffernes and covere it all in tape.

The rest is software. See files.

As noted in the first log, I have done something similar with an Arduino.


Something completly different - just a display that is slightly reminiscent of the Matrix display - lines that drop down. Pardon the ugly start, after a while it looks better.

plain - 2.41 kB - 04/16/2023 at 12:13


Badge Dial.txt

Final code.

plain - 5.53 kB - 03/31/2023 at 14:20


Badge Dial 0.5.txt

(Coded after the event) Displays the digit dialled in register 7

plain - 2.64 kB - 03/28/2023 at 20:13



Video showing starting the program, dialling "5" and seeing R7 on the display reach 5.

Audio Video Interleave (AVI) - 2.20 MB - 03/27/2023 at 20:37


Badge Dial WIP.txt

The code as it was during the presentation. This is "hand assembly" - entered the codes directly on the board

plain - 900.00 bytes - 03/25/2023 at 23:51


  • Final

    Michael Möller03/31/2023 at 14:20 0 comments

    Added code to display readable digits.

    See the BadgeDial.TXT for final software. Remember it's only a txt file that looks like assembly. Could not be bothered to code all digits, but principle is shown. It sort of was "complete" at the competition, but working software makes it more complete.

    The video is via YouTube, too large to upload as a file here 

  • Finishing a few days later

    Michael Möller03/27/2023 at 20:24 0 comments

    For the competition I only barely got the software to recognize that I had dialled a number, but not which number.

    Version 0.5 can reliably detect the number, but it only runs for one digit.

    Textfile of the code uploaded, and a brief video, too.

  • Live

    Michael Möller03/25/2023 at 21:54 0 comments

    This is live editing during the Hackaday Berlin 2023 conference.

    I got as far as being able to detect that I started dialling but not yet count the "ticks" when the dial returns. Challenge is the contact debounce.

    The dial has been temporarily taken from my MasterDial ( which I had brought along just so I had something to show what I meddle with.

    Broken donor of rotary dial

    Best Maskingtape Engineering(tm) used in construction :-) (Look at the large pictures on project page for details)

    Code development was impeeded by no assembler - only the buttons on the badge were used. The textfile is my code in "handassembly".


    Stop press: It won best in the Hardware Category ! (There were only two entries, but nevertheless)


    I am busy, even after having won the award to "Finish" it - at least to display the digit dialled  - I'll settle when it is visible as a register value in the default page-display

    Now it is time to go home here (3AM, in new Summer time) - next log entry will be a video of it working .

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Lutetium wrote 03/28/2023 at 14:32 point

Congratulations!  Staying up until 3AM is part of the game, but sleep never hurts.  :)

Thanks for writing it up.  

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