Share this project


Share this project

A 15cm Interactive Binary Ruler with Seven Logic Gates, Four Flip Flops and a Four Bit Binary Counter.
A 15cm Interactive Binary Ruler with Seven Logic Gates, Four Flip Flops and a Four Bit Binary Counter.
1,124 backers pledged AU$ 38,163 to help bring this project to life.
Aaron, Abdelatif Elaissate, and 7 more people like this update.


Only backers can post comments. Log In
    1. Missing avatar

      Volker on

      I received mine last weekend (Germany).
      It works well but I have the button bounce problem on nearly all buttons.

    2. Carsten on

      Got mine on Dec 3rd (south west Germany)

      So, if i see it right, we should update the Digirule to not bounce. Bradley, will you include Bachers Code to fix the reset problem?

      so long, Carsten

    3. Missing avatar

      A Martin on

      Bradley, received mine a couple days ago (Northern California), got a battery last night. There was one cold solder joint (one of the legs of the flop's "S" input) that I had to touch with a soldering iron. Some of the screen printing on the back isn't very sharp-- it's hard to see the CLK inputs, for instance.

      Other than that, I'm pretty pleased with this. (The button bounce doesn't bother me that much.)

    4. Marco Van Den Hout on

      Received my 2 DigiRules, bought batteries online from a big music instrument store here in the Netherlands, and tested one. I do have button bounce problems, and will think about getting a PIC programmer although those are new to me (I do have Arduinos but I program those through USB). It's too bad but not deal breaker for me, happy to have them anyway!

    5. Missing avatar

      J. Bacher on

      Hi, received mine, (South Germany) thanks. As expected the buttons bounce a little.

      By the way as reported by Jaap Scherphuis the FF code is buggy. The SR error code is not reset when another type is selected and toggling results in both outputs to toggle. This is the fastest way to fix it:

      Sub DoFlipFlops()
      ' check the change flip flop button
      If FlipFlopSelect = 1 And FlipFlopSelectPressed = false And ButtonsEnabled = true Then
      ButtonDebounce = BtnDebounceTime
      ButtonsEnabled = false
      FlipFlopSelectPressed = true
      FlipFlopSJTDLED = 0
      FlipFlopRKLED = 0
      'reset to fix FF code
      FlipFlopQLED = 0
      FlipFlopNOTQLED = 1

      If WhichFlipFlop > 3 Then
      WhichFlipFlop = 0

      This resets it each time you change the type.


    6. Rene Flemming on

      Received, Dippoldiswalde, Germany, no problems, but the cr1220 is a unusale type of battery in germany, i had to drive 25km for a dealer. :)

    7. Missing avatar

      Robert Ralston on

      Button debounce feedback.

      One DigiRule (have not yet tried my other 4). Running on Energizer 1220 battery. Tried in several different locations: on my desk about 2 feet away from an iMac; in a waiting room where I don't see any other nearby electronic equipment; people do have cell phones, turned mine off.

      Put DigiRule on flat non-conductive surface. Activated buttons with a non-conductive plastic "coil tuner tool" so I'm not touching the DigiRule with my skin at all.

      Results for 4 bit counter (going up always started out from 0000; going down always started out from 1111)

      direction presses readout
      up 12 1111
      down 14 0000
      up 13 1111
      down 15 0000
      up 12 1111
      down 13 0000
      up 13 1111
      down 14 0000

      Conclusion: except for one time going down, there were always too few switch presses required. These results were immediate upon turing the DigiRule on.

      In a couple of days I will attach my PICKIT2 using its standalone application and see if I can at least "see" the 18F43K20.

      If that works, I will try uploading the hex file posted.

      If you want a field test with any new hex files, I'll be glad to try them.

      I will also try the other 4 DigiRules I have.

      Would you please verify for me the ICSP connections:

      My PICKIT2 connects, starting from the triangle on it: Vpp/MCLR; Vdd; Vss; DAT/PGD; CLK.
      Do the ICSP connections on the DigiRule, starting from its triangle marker, correspond to those on the PICKIT2?

      It's been a couple of years since I worked with my PICKIT2 so I need to refresh and make sure that I don't supply too high a voltage from the PICKIT2 to the ruler, as I remember that the PICKIT2 can supply something like 100mA.

      RRalston (KJ6HFR)

    8. Missing avatar


      Oh, and might there be another run of these? Or multiple, lower production runs so that these are available long term? I can imagine giving these as gifts, or other people wanting them over the long run.

    9. Missing avatar


      Got mine! LA, CA, USA. Unfortunately I didn't think to get a battery in advance, so I'm stuck at work waiting to get out before I can go buy one.

    10. Missing avatar

      Alex Limonov on

      Received Dec 4 in Cupertino, California.

    11. Missing avatar

      SidB on

      Received mine today in Bristol, UK. Sorry to report that I have the bounce issue too - particularly noticeable on counter-up. Regarding @creator's query about power source, I'm using a cheap CR1220 from eBay.

    12. TIBORGAM on

      I have not recived yet but as i can been informed the bouncing can be easily solved with some software configurations instead of changing hadware ( it would mean all the work for the backers). So the main solutions is software? In case of affirmative what is the solution?:
      + We have to get a pickit 2 or 3?
      + We will upgrade the software tested by you on a bouncing ruler?
      + You will give us a link to donwload the new software?
      + You will explain how to use pickit and a tutorial to fix it? ( Cause not all people are progrmmers and know about electronic)

      Thanks, we wait your answers creator.

    13. Missing avatar

      Robert Ralston on

      California US, received Dec. 3rd.

    14. Lafazar

      Received 10 a while ago but only now got around to buyng batteris and trying them out. The debounce is pretty bad IMHO. I definitely need an upgraded software before I can give these to students.

      Off to look where to to get a programmer...

    15. Missing avatar

      Schallrich on

      Near Berlin.
      Works fine :D
      I love it!!

    16. Missing avatar

      Peter Schoenknecht on

      Bielefeld received 10 rulers...yesterday...
      hope a****n is quick delivering.
      Will have a nerd Weekend ;-)

    17. Missing avatar

      kuei tung on

      Taiwan, New Taipei City, received, thanks
      And so buy the battery after the test

    18. Missing avatar

      Aaron on

      After some experimentation, I have found that by placing the DigiRule in an anti static bag and using it while it is in there, the button bounce is significantly reduced.

    19. Missing avatar

      Aaron on

      Mine's arrived. I have the button bounce issue as well.

    20. Paul Court on

      London, UK here. Mine was waiting for me when I got back from work tonight.. Works great although if I were being super critical I would say the switches need a bit of programmed debounce. Still great fun though - now can I remember all the modes of a flip flop...

    21. Missing avatar

      Bitfogav on

      @terry - You will need a 3v CR1220 battery.

    22. terry on

      Received - looks good but can't try it as it never come with a battery, what does it take ?

    23. Rob Bezouwen

      Also NL, received today here

    24. Henry Paulissen on

      NL here, received it as well today.


    25. Missing avatar

      Dimitrios Bogiatzoules

      I live in Germany an got my pack of five today! Great gadgets!

    26. Amir Soltani on

      Thanks Bradley, it's a nice tool and fast as your other projects.

    27. Jaap Scherphuis on

      They arrived today, and yes, there is a bounce problem. It doesn't really matter much I think, as it is always easy to correct the input.

      On a different note, a minor bug in the flip-flop code:
      On the SR flip-flop, the invalid state shows as both state lights off. If you then go to the toggle or JK flip-flop in its toggle setting, then both the state leds switch on and off at the same time.

    28. NialP

      As Asbjørn Mikkelsen say's below, with the source code and a PIC programmer then you could manually change de-bounce in the code to get it how you best find it working. I Don't know how many people here have said programmer (I do but rarely use Microchip MCU's so it doesn't get alot of use any more) or are willing to buy one just to access one device, better to put up with it and save the money and buy a good ARM based dev kit instead...

      I have just found another wierd little bug in that the counter seems to lag/stall for a few seconds between 2 and 3 when counting up at about a 1 click a sec rate. It lights up LED #2 but then freezes for between 2 and 5 seconds after the next up button press before lighting up LED #1 along side #2. I have replicated it a couple of times on my device but it took alot of presses and it always happened when slowly counting. Very odd.

    29. NialP

      The "Double Press" issue was easy to replicate on my board and is common with these particular buttons due to them being designed to be under a more solid pad and/or button cover inside a product (like a calculator or kid's toy etc...) rather than being used as stand alone buttons.
      To get around alot of the "double presses" is easy... use the end of your thumb nail and make sure you are hitting the brass color central circle dead on and that should stop "button bounce" 9 times out of 10 at least. If it really annoys you that much then I guess you could de-solder them and buy some SMD Buttons with black plastic inserts, just like the through hole versions you get in any Arduino/Dev Board or mixed Component Kit.... A lot of work for something just mildly annoying to a few peeps tho.

    30. Asbjørn Mikkelsen

      I got mine today, Norway.
      I tested one of them, and yes, I have some bounce, not much, just some times, mostly noticable on the clock, but also the s/j/t/d input. You don't have any hardware debouncing, so I guess you need to adjust the software debouncer just a tad?

    31. Ivan Saponenko on

      Ruler is awesome, this double press bug doesn't really made it worse, but I encountered this problem too. My guess is that little current traveling through a finger could cause something to go wrong! Thank you for the ruler, hope you'll find the bug!

    32. Missing avatar

      BuildTheRobots on

      1) realised I can't edit comments.
      2) realised other people had already replied (I should have scrolled down)
      3) seems to be relatively endemic, the two of my 5 I've unpacked exhibit same symptoms
      4) after 20-something years of failing, 10minutes sat with the ruler and I finally _understand_ xor -thank you =D

    33. Missing avatar

      BuildTheRobots on

      I've been having similar issues where I'm either missing or getting double-button presses. Especially with the left-most A+B buttons but also noticeable with the counter (it'll sometimes jump up two or three).
      I was actually going to send an email today asking if the de-bounce code could possibly be reviewed as that's how the problem seems to manifest itself to me; when toggling inputs for the logic gates sometimes the act of taking your thumb off A is enough to toggle a state change (so it'll only stay lit when you're holding it down, etc).
      After a quick bit of testing and re-watching your videos, this is far less of a problem when the ruler is sat on a desk. If i'm holding it in my hand (I'm guessing due to flex in the board) it becomes really noticeable.

    34. Missing avatar

      Andy on

      Sorry, you're comment seem to have overlapped with mine... I'm using a standard CR1220 battery. Using a pen to press doesn't make a difference for me. It's maybe one out of ten (without doing any statistical engineering)!?

    35. Missing avatar

      Andy on

      Hi Brad, I can confirm the behaviour that sometimes there is some keybouncing. I've only unpacked one of the five I have, but noticed this also. I'd say for me it is irritating, not annoying. For example on the counter, sometimes you can see quickly two counts, when you only pressed once. I tried it away from other electronics, but it doesn't make a difference.

    36. Bradley Slattery 7-time creator on

      Thanks for the comments everyone. Unfortunately I don't have one of the final production DigiRules to check myself as I wanted to get them sent out to you all ASAP. It seems that I should have got them to send me some so that I could test them myself. I just can not understand how this contact bounce is occurring because I have done extensive testing and have simply not had that problem.

      For those who have had the contact bounce issue could you please post a comment letting me know exactly what you are using to power it up? are you using a PICKIT2, a CR1220 battery or some other power supply etc...?

      I am currently waiting for my own set of DigiRules to arrive and again, I can't do my own testing until they get here. For those who are having the issues, how annoying is it? How often has it been happening, does it do the same thing if you press a button with a pen or something similar?

      Any feedback here would be very much appreciated. thank you guys!

    37. Missing avatar

      Jens Leilich on

      Each of my five shows this behaviour. Sometimes the switches bounce, so the counter is clocked twice or an input is set from 0 to 1 to 0 again.

    38. Deepra Smith

      Maybe need software update to filter quick succession of press.

    39. John H

      I've noticed this happen occasionally. I put it down to big fingers on small buttons.

    40. Missing avatar

      N. Short on

      I haven't had any issues yet, will let you know if anything crops up.

    41. Missing avatar

      Andrew Mayes on

      I received mine today and I have noticed that there seems to be an issue with button bouncing. It's not a major problem but it would be nice to get a software update some time in the future to correct this.