HP15C Calculator Emulator

Description

So I've always wanted an HP15c calculator and never got the chance to buy one.

So this is my take on building one. It is designed with only through hole parts. For easy soldering.

The brains of the calculator is the ATMEGA328. It takes care of everything (display, keypad scanning, sound, clock, etc).

I decided to use the ATMEGA328 since it is pretty common in the Arduino community and it is one of the few microcontrollers still produced as a through hole part. No other semiconductor is used.

Even though the ATMEGA328 is an 8 bit microcontroller and running at 8Mhz, it is still pretty fast. In the end, the emulation is about 4 to 5 times faster than the original.

I've added a speaker for audible Keyboard feedback. And a 32.768khz crystal for the real time clock.

The emulator can run any of the Voyager series calculator.

I've added a "Key Decoder", In programming mode, the names of the keys are display on the header of the display.

Details

Features:

All Through Hole parts. (easy to handle and solder)
Runs about 4 to 5 times faster than the original.
Memory registers 65 (Same memory as the original).
Continuous memory (Memory is not lost when calculator is turn off).
Auto power off
Runs on a single ATMEGA328 8 bit microcontroller running @ 8MHz (same as Arduino Uno)
Speaker for audible keypress feedback
192x64 lcd display
Display Backlight
Has a real time clock. (Uses a 32.768KHz crystal)
Uses a single CR2032 3V battery.
Power consumption: 1µA off, 350µA idle, 3mA working (this is with speaker and backlight off)

The 3D printed case is available at thingiverse.

And the keyboard overlay is available here:

The ATMEGA328 is located beneath the display:

Youtube video:

Discussions

Serhiy Striletsky wrote 01/09/2022 at 11:52

Very nice and all but it's a pity. You don't even give the name of an LCD controller, which makes provided firmware useless so I don't even mention a full source code. I don't think that anyone will try to steal and commercialize such a niche project, but a source to be able to adapt it to a different LCD could have been nice from your side.

So it's not hackable and not diyable, the whole post is just an advertisement of you or connected party selling kits.
Problem is I don't like the LCD provided with a kit that has an additional PCB and makes this thing too thick to my taste. Pity.

Would you make the source code available at least to those who bought a kit?

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Niels wrote 04/12/2022 at 16:54

I totally agree with you about this perspective.

The author is merely advertising his semi proprietary kit. :(

It's a shame and IMHO, being a product and not DIY, it doesn't belong here on hackaday.

I would have loved to make my own desktop version with large 4" backlit LCD. :P

Maybe one of the wizards on github and sourceforge have what we really need?

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CYUL wrote 05/16/2022 at 21:51

Alas, this seems to be the norm for retro computing projects. You should have seen (or read) the reaction when I suggested someone who was selling an extension for an Apple II to share the source code… These are the times we live in: “me, myself, and I”. People make you feel like a loser when you share stuff for free nowadays.

We all lose in the end. Where would we be if Woz had kept the Apple II design secret?

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alxgarza wrote 09/20/2021 at 21:10

Emulating a HP41C https://youtu.be/wpQaDlrgTQk

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bboyes wrote 09/04/2021 at 15:55

Is the code available? How has it been verified to be correct (if I were to use this at work there are consequences). I'm on the notification list for kits. This is a really cool project. I am a little surprised it all fits in an ATMEGA328.

Are you sure? yes | no

alxgarza wrote 09/04/2021 at 23:03

The firmware is available for download, this is an emulator not a simulator.

Are you sure? yes | no

jay wrote 09/16/2021 at 05:54

Love this. Is the firmware hackable? Can I change the functionality of the keys?

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erlles2140 wrote 09/01/2021 at 20:36

True craftsmanship

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[deleted]

[this comment has been deleted]

alxgarza wrote 08/23/2021 at 17:03

This is an HP15C emulator. The HP15C did not have graphics capability. There is a standard SPI header for uploading new firmware.

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Dan Miner wrote 08/22/2021 at 04:36

Excellent work. Where can I buy that display? Where can I get the emulator code and ROM image of the HP-16C? I'd like to build my own HP-16C emulator.

Edit: I just noticed you are selling these on Tindie. I will buy one if I can emulate the HP-16C.

Are you sure? yes | no

alxgarza wrote 09/07/2021 at 02:00

It can emulate any of the Voyager series. Tindie has the HP15c and HP16c versions.
For more info checkout https://paxer.net/voyager/

Are you sure? yes | no

alxgarza wrote 09/07/2021 at 17:05

You can download the hp16 firmware form: https://paxer.net/voyager/

Are you sure? yes | no

ziggurat29 wrote 08/21/2021 at 16:07

magnificent.

Are you sure? yes | no

HP15C Calculator Emulator

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