MP-29 Tactile Touchscreen Calculator

I built a touchscreen with tactile feedback (it feels like pressing a key), then I built a programmable scientific calculator around it, and then I gave a presentation at the HPCC (Handheld and Portable Computer Club) 2020 virtual conference. The calculator uses two P1 chips.

Here's my half-hour talk on youtube: https://youtube.com/watch?v=VCKk9GyXi3Q

Comments

  • mpark,

    This is a great accomplishment. Being a former HP employee and a HP calculator lover, my hats off to you in creating a HP-like calculator utilizing a pair of propeller 1 chips.

    Great idea/design in creating some tactile feedback using touchscreens

    With the new P2 essentially now available are you looking into migrating your design to the P2?

    I would love to take a look at some of your propeller code at some point, when/if you are willing to share...

    In reference to the power usage of your design, did you explore putting the propellers into their lower power modes (i.e. CLKSET) or stopping cog(s) when not needed?

    Keep up the good work and congratulations on your creation :smiley:
  • Thank you, @Francis Bauer! Was HP the magical place I always imagined? (Don't tell me if not.)

    I haven't kept up enough with the P2 to think about migrating, though I'm sure the P2 could replace both P1s without breaking a sweat.

    Re low power: when the calculator goes to sleep, I do switch both Props to RCSLOW. I'm pretty sure I stop unneeded cogs. I actually suspect the battery isn't living up to its 2000mAh rating, but disassembling the calculator is enough of a pain that I'm just leaving it as-is.

  • First thought was WOW! Nice job especially being an HP. Wish my old HP41 had this sort of interface. Yes it could have the keys all sorts of custom mapped to programs etc, but this sort of interface would have eliminated having to carry all the keyboard overlays created for all the key maps.
  • @frank freedman Ah, another man of culture, I see.

    Any more HP fans coming out of the woodwork? RPN represent!
  • Hi

    Oh man that is such a good example of lateral thinking.
    I HATE touch screens so its nice to find a good use for them!
    I would think this type of implementation of a programmable keypad must have application elsewhere, where multiple choices/scenarios need to be made from a hand device where fixed label buttons just won't do.
    Love the scissor action solution to tactile feedback.
    Thanks for sharing

    Dave
  • I am an HP fan.

    Several years ago I discovered SwissMicros.com and bought a couple of their credit card sized HP clones. Interesting implementation!

    (I also have owned many actual HP calculators through the years.)
  • TubularTubular Posts: 4,086
    edited 2020-10-12 - 21:17:10
    I found that talk delightful, Michael. Hardware innovation, history, bit of math and the propeller. What else could one need?

    I know its not your current priority but check out the 'propeller limbo' thread for some details of getting the propeller current down to around 1uA while still being somewhat 'alive'.

    Also the techniques you have implemented could also apply to low power graphic lcds just as well

    My calc is an HP 20S that I really like, purchased in a US trip back in 1988 or 91. I have to press the keys a lot harder than i used to, in order to make reliable contact.
  • Touch keypads of any kind have just about dried up, most were made in China. Two keypads that I was thinking about using, went end of life on me. Using the P2 would be a great option.
  • Thanks, @Tubular! Is this the thread you meant: https://forums.parallax.com/discussion/129731/prop-limbo-how-low-power-voltage-can-it-go? Looks a bit beyond me at first glance but I'll try digging in. Thanks for the pointer.
  • mpark wrote: »
    @frank freedman Ah, another man of culture, I see.

    Any more HP fans coming out of the woodwork? RPN represent!

    Okay, okay I'm in! In college i could work out problems faster on my HP than the TI students! And it helped me with understanding how Forth works (tachyon).
    RPN!!! lol
  • mpark wrote: »
    Thank you, @Francis Bauer! Was HP the magical place I always imagined? (Don't tell me if not.)

    I haven't kept up enough with the P2 to think about migrating, though I'm sure the P2 could replace both P1s without breaking a sweat.

    Re low power: when the calculator goes to sleep, I do switch both Props to RCSLOW. I'm pretty sure I stop unneeded cogs. I actually suspect the battery isn't living up to its 2000mAh rating, but disassembling the calculator is enough of a pain that I'm just leaving it as-is.
    I worked at HP from 1980 - 1999 (Agilent Technologies through 2010).

    While Bill and Dave were still alive, HP was a magical place, it essentially was a family atmosphere. You still worked hard, but you were treated as a human being, not just a number on some spreadsheet. The "HP Way" was more than just a collection of words, it was practiced. Management-By-Walking-Around (MBWA) was alive and well and done by all levels of management, including Bill and Dave themselves. Dave was fair, but he would still let you clearly know when you strayed from the "HP Way".

    One of the key points of the "HP Way" was to innovate new products/ideas as more important than directly shooting for market-share. If you actually created an innovated product/idea you would automatically get market-share...

    As Bill and Dave stepped back from the day-to-day of HP, things did start changing to the whims of the MBA's and the bean-counters.

    I suspect that there are still some pockets of the old HP around in (HP,Agilent , Keysight), but they are getting few and far between...

    Keep up the good work...
  • Thanks for the reminiscences! Dang. Those really were the days.

    Ooh, maybe Parallax is the new HP :)
  • I was having trouble in a chemical engineering course. I couldn't figure out how the other students managed to get through tests as fast as they did.

    I hoped a new calculator would help. I purchased a HP28S. I practiced using Newton's method on it a bit and when it came test time I was thrilled with how fast I was flying through the test. I didn't finish last but I also didn't finish first. It was then I realized all the other students were already using HP calculator.

    The HP didn't give an edge over other students but I was no longer being hindered by my old calculator.
    I was amazed something like a calculator could make such a big difference in a class.
  • Duane Degn wrote: »
    I was having trouble in a chemical engineering course. I couldn't figure out how the other students managed to get through tests as fast as they did.

    I hoped a new calculator would help. I purchased a HP28S. I practiced using Newton's method on it a bit and when it came test time I was thrilled with how fast I was flying through the test. I didn't finish last but I also didn't finish first. It was then I realized all the other students were already using HP calculator.

    The HP didn't give an edge over other students but I was no longer being hindered by my old calculator.
    I was amazed something like a calculator could make such a big difference in a class.

    I agree. Once you understand the stack manipulation aspect, man can you fly through calculations! Lol
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