Graphing calculator feat. STM32F412VGT6

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

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..

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

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

Schematics:
https://www.numworks.com/resources/engi … chematics/

[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?

It looks like more high-level C++ with IEEE fp:
https://www.numworks.com/resources/engi … hitecture/
https://github.com/numworks/epsilon

The electronic design is rather simplistic:

• An STM32F412VGT6 MCU
• An ST7789V 320×240 LCD display
• An RT9078 300mA LDO
• An RT9526A linear LiPo charger
• An RGB LED

https://www.numworks.com/resources/engi … cal/parts/

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)..

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

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

The high cost of calculators is mostly limited to ti – hp is largely out of the game for educational calculators.

Ti was incredibly smart in it’s marketing of calculators as they encouraged text book authors to write their calculators into textbooks ..

The Japanese we’re too foolish to replicate that strategy. They thought they could win on high performance and low costs.

They couldn’t have been more wrong.

I find even the Japanese calculators seem to be somewhat overpriced for whats in them

e.g. Nearly $40 AUD (about $30 USD) for a Casio FX100 from a local office supplies warehouse.

https://www.officeworks.com.au/shop/off … -ca100aupl

Cost of production would probably be $5, and they have been churning them out for years, so there is no ongoing R&D budget

that’s probably a case of inefficient market place or inefficient vendor: a FX115ESPLUS goes for < $13, a FX300ESPLUS for < $10 at walmart.com, lower when on sale.

hardly unreasonable. No idea how they are comparable.

Yes. Only 20 million people in Australia, mean we pay an “Australia Tax” due to insufficient demand.

This can usually be overcome by buying direct from China (eBay or AliExpress) and waiting for it to arrive on the container ship

Another reason for poor calculator sales, is the fact that smartphones can emulate a very capable calculator, so why would you want to carry both around in your brief case.

RealCalc is one of my favourites

https://play.google.com/store/apps/deta … s.RealCalc

.. but there are plenty of others.

https://downloads.tomsguide.com/Algeo-g … 54035.html

http://www8.hp.com/us/en/campaigns/prim … r/app.html

.. having said all that, I am actually a bit of a calculator fan. As well as some classic Casios, like the FX-602P and FX-702P there is, somewhere in this house an ancient TI 30 and a Commodore LED 774D… and then of course there is this….

… no batteries required.

I have some old calculators too!
A (little) programmable TI 51 III bought when I was at school

an old mechanical Olivetti

an old Canon with nixie and an old Commodore plus some others.

I had one of those old TI’s with led display.

But my favorite are casios. a fx-39 from way back, and i still have a fx-82 that’s working nicely, aside from the power on switch, almost 40 years after I got it. back then people were expecting 10-yr life for the lcd.

but my favorite is the 12c. I have about 10 of them laying around between my house, backpacks and my offices. that’s a marvel of engineering.

I have one of those Friden calcultors.
It was working several years ago, but not anymore : I need to find which transistors had broken, but too lazy …

is the fact that smartphones can emulate a very capable calculator
There are almost all famous calculators available on android/ios (ie HP/TI).. My favorite is the HP-42S with 34digits precision (Free42)..

I took a quick look at Free42 and I must say, I’m quite impressed. I didn’t think there were any free Adroid RPN calculator emulators. Thanks.. yet another toy to distract me when I should be working

at school, we only had slide rules and log tables.
my dad found a couple of cylindrical slide rules and some 10 place (or more ??) log tables.
i’ve a ‘standard’ slide rule on my bookcase, i do wish i’d managed to snaffle one of the cylinders though.
stephen

I also learned how to use slide rules and log tables, long division and how to manually calculate square roots (though I’m not sure if my ancient grey matter could still manage that last task).

I guess I’m the crossover generation (also known as an old fart ).

Pocket calculators weren’t a thing, until I was in secondary school, and I still have a slide rule or two somewhere.

I also learned engineering drawing on proper draughtsman’s tables, with t-squares, propelling pencils and Rotring pens, just as CAD was starting to become more mainstream.

As a result, I’m actually pretty good at sketching and drawing by hand.

1st angle projection – look and put on other side.
3rd angle projection – look, bounce and put on same side.

one of the tutors, always have pencil and paper to hand, a sketch and words etc, etc.
similar for sketching, they usually end up as an isometric view, 30 or 45 degrees
i’m currently classing myself as a sad old git
‘O’ level grade 4 – same for metalwork. then in Uni 1st year, intersecting / crossing tubes. develop the cut outs.
and before you ask, no chance. actually maybe not. funny how memory works, just enough to recall the other bits.
had someone looking at my answer in the tech drawing exam.
i explained it to him afterwards.

stephen

I learned to manually calculate square roots too but not slide rules, I believe that where not in use in italian school. I too learned basic geometric drawings at school between 11 and 13, then artistic drawings and finally engineering drawing at university.
I still have Rotring and Staedler ink pen.
But then I started early using CAD, main reason was that it was very simple to duplicate a drawing.
I started drawing cave maps, I was a caver but I am still able to go in simple caves without very long pits.

my mother worked as a tracer before marrying.
somewhere i have one of her tracings, cross section of a jet engine, about 10ft by 6ft.
stephen

our stm32duino calculator does a different feat, it isn’t quite that beautiful but maybe it is possible to draw an fft chart on an ili9341
what our stm32duino calculator excel at is that it can crunch floating point numbers at 500 mflops – no other beautiful stm32 f4 calculators may come close, but that’s provided you use *single precision* math and hardware floating point and overclock the stm32f407
http://www.stm32duino.com/viewtopic.php … &start=160