Graphing calculator feat. STM32F412VGT6

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Squonk42
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Graphing calculator feat. STM32F412VGT6

Post by Squonk42 » Tue Sep 05, 2017 8:30 am

Just found this one.

Schematics, 3D STL files and software available under a Creative Commons license on Github:
https://www.numworks.com/
https://github.com/numworks

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Pito
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Re: Graphing calculator feat. STM32F412VGT6

Post by Pito » Tue Sep 05, 2017 9:06 am

Nice!! I love this topic!
As an user of WP-34s (built it myself from HP-30b), the most powerful scientific (non-graphing) calculator on the market.. people say
http://commerce.hpcalc.org/34s.php
I've been thinking to port it to STM32 since ever (it is open source) as the original mcu there is a rather obsolete stuff (atmel arm, 6kB ram, 128kB flash).. Always hit the case/keyboard issue - quite difficult unless you plan to produce 1mil units of it..
Last edited by Pito on Tue Sep 05, 2017 1:37 pm, edited 1 time in total.
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RogerClark
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Re: Beautiful graphing calculator feat. STM32F412VGT6

Post by RogerClark » Tue Sep 05, 2017 10:56 am

I can't see the files for the schematic or PCB.

I can only for the 3D files for the case and for the firmware source code

dannyf
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Re: Graphing calculator feat. STM32F412VGT6

Post by dannyf » Tue Sep 05, 2017 11:11 am

This looks interesting. I wonder how those little things parse the input and perform the calculation. Bcd?

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Pito
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Re: Beautiful graphing calculator feat. STM32F412VGT6

Post by Pito » Tue Sep 05, 2017 1:39 pm

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Squonk42
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Re: Beautiful graphing calculator feat. STM32F412VGT6

Post by Squonk42 » Tue Sep 05, 2017 2:11 pm

dannyf wrote:
Tue Sep 05, 2017 11:11 am
This looks interesting. I wonder how those little things parse the input and perform the calculation. Bcd?
It looks like more high-level C++ with IEEE fp:
https://www.numworks.com/resources/engi ... hitecture/
https://github.com/numworks/epsilon

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Squonk42
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Re: Graphing calculator feat. STM32F412VGT6

Post by Squonk42 » Tue Sep 05, 2017 2:18 pm

The electronic design is rather simplistic:
  • An STM32F412VGT6 MCU
  • An ST7789V 320x240 LCD display
  • An RT9078 300mA LDO
  • An RT9526A linear LiPo charger
  • An RGB LED
https://www.numworks.com/resources/engi ... cal/parts/

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Pito
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Re: Beautiful graphing calculator feat. STM32F412VGT6

Post by Pito » Tue Sep 05, 2017 2:48 pm

Double (or single) IEEE precision is not enough for a calculator. Most cheapo calculators use up to 25 BCD digits math, and the better one use ie. decNumber lib and do up to 50 digits. From the sources there they use simple float/double - that will not work (as they will soon recognize).. :)
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Squonk42
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Re: Graphing calculator feat. STM32F412VGT6

Post by Squonk42 » Tue Sep 05, 2017 3:46 pm

I agree, I was kinda shocked when I saw that...

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Re: Graphing calculator feat. STM32F412VGT6

Post by RogerClark » Tue Sep 05, 2017 9:33 pm

With the schematics only being available as PDF, and no PCB files etc, they obviously don't want anyone to actually build one themselves.

One thing I have noticed about calculators is their high cost in comparison with the cost of the hardware.
i can buy a Android phone with far more computing power, for less than the cost of a graphing calculator.

Some of this seems to be because schools only allow students to use recognised brands and even specific models of calculators, so there is no market for a decent calculator unless its "approved", and education authorities have nothing to gain by reviewing and approving cheaper alternatives, as its the students who normally have to buy the calculators

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