Ben Heck’s DIY Calculator

Learn more about DreamBoard at - element14.com/dreamboard
element14.com/tbhs - In 1972 (when films were silent) three men invented the first scientific pocket calculator. In todays episode Ben and Felix build their own DIY graphing calculator using a Raspberry Pi. The build is also the first to feature the Formlabs Form 1 3D printer.
Like The Ben Heck Show at - / benheckshow

[@pacman10182]

"graphing calculator" I didn't see one graph.

[@jonathan__g]

tyler roberts I came for graphs. I was disappointed. :(

[@Skwisgar2322]

tyler roberts I think the software for a graphing calculator is a bit above their pay grade.

[@pacman10182]

***** then somebody lied. in the g+ post: "Ben & Felix hack a graphing calculator using a#RaspberryPi & @formlabs SLA 3D printer this week:" and in the description: "In todays episode Ben and Felix build their own DIY graphing calculator using a Raspberry Pi."

[@Skwisgar2322]

tyler roberts I suspect their intention was to make a graphing calc, and they had to scrap that when they realized how much more work went into that?

[@pacman10182]

NapoEz3 the code already exists, no need to do what has been done already.

[@NikolajLepka]

yess Felix uses OSH Park!! :D welcome to the club, man! Also, it's nice to see a Felix-centric episode, this guy deserves more screen-time

[@Mixbag]

Nikolaj Lepka too bad he messed up the Board... always ALWAY print and check before you order PCB boards. this is an expensive mistake. he should really know better

[@RetroSwim]

Nikolaj Lepka They're so expensive though!

[@NikolajLepka]

***** they're fairly inexpensive for small production runs, a few tens of dollars for three boards you made isn't so bad, many other board houses have cough up a few hundred dollars

[@RetroSwim]

They charge by square inch of board area, it's OK for very small boards, but there are Chinese fab shops that offer way better value once you go over 4-5 sq. in.

[@NikolajLepka]

***** Chinese fab shops don't always meet EU regulations, so they're mostly out of the question

[@93maverick]

Felix is way too hyper

[@Jeffball610]

Most of this is beyond my current understanding, but I love it. I'm also happy that you made a custom PCB even though it didn't quite work out. Can't wait to see more of this stuff.

[@richfiles]

I used to overclock TI graphing calculators, and made serial port accessories like flash memory expansion, speakers, etc. I had my TI-85 and 86 modded with a small port on the bottom that could accept small accessory cartridges.

[@o0julek0o]

16:45 - In the background, we see the elusive nerd-cocaine. It's what Felix takes to remain so calm, at literally all times.

[@hristaki99]

o0julek0o Cocaine doesn't help you remain calm, quite the opposite actually.

[@o0julek0o]

"ELUSIVE NERD-COCAINE". The word 'elusive' and 'nerd' are prefixed to cocaine to imply that it does the opposite to normal cocaine.

[@radioactivewaste4756]

o0julek0o lol xD someone needs to be rushed to the burn ward... *in the background 999 is rung*

[@o0julek0o]

Kiran de Silva Yeah, our little friend who can't read.

[@n_3719]

o0julek0o Ya crazy? That "elusive nerd-cocaine" is circuit-board etching salt

[@jonathanevans5835]

YES FELIX YOU ARE AN ABSOLUTE CHAMP! More vids with the great Felix please!

[@AppleKnowsBetter]

God, that T-Shirt at 23:25

[@DustinRodriguez1_0]

I'd set the calculator up to just boot into a Python interpreter. That's the best calculator I've ever encountered!

[@matthewferraro8020]

Dustin Rodriguez then do it!

[@SianaGearz]

I think it needs simpler hardware really, one that doesn't need a whole operating system to manage it. An STM32 can address external RAM and it should be able to run YACAS. Well, except YACAS probably won't quite fit into its Flash memory, i think it'll come down to about 300K, but you could have a MicroSD or an i2c serial flash, or parallel flash on the memory bus. Other possibilities are Erable and Xcas... Any further ideas? Other hardware suggestions?

[@gu4xinim]

Shame the pi module version didn't work out. It would be amazing to see non wires everywere felix/ben project.

[@StoneFlange]

Glad to see more of Felix! This show and its projects get better each time :-)

[@Bbogita]

I loved seeing the trial and error process in this project! It's nice to see that other people make mistakes too. This was one of my favorite episodes of all time!

[@PrinceXTC86]

The T-Shirt at the end was TENSE!

[@PoLoMoTo2]

I feel so bad for Felix, he did great in this episode if anything he just seemed a bit nervous, and I really wanted to see that compute module actually used in a project.

[@raffitz]

The function you're describing is that of a Decoder, not that of a Multiplexer. And you could have used just two GPIO pins rather than three, by using an Encoder instead: The common pin of the pad goes to either VCC or GND, depending on whether the Encoder inputs are negated. Then, the four directional pins go to the Encoder inputs and the two Encoder outputs go to GPIO inputs. If the encoder is 8 to 3, which are the most common discrete components, both in the 7400 TTL series and in the 4000 CMOS series, then just short the 4 most significant bits to either GND or VCC (depending on whether inputs are negated). While your solution is nice if you have a Decoder but no Encoders lying around, I think it lacks grace and is needlessly complicated.

[@raffitz]

raffitz Follow-up: You could use a proper multiplexer as well, but you'd still use that third pin. You'd connect the common pin to either VCC or GND, just like with the encoder, and the directional pins of the pad to the inputs of the multiplexer, and the two output GPIO pins to the selection inputs of the multiplexer. Then you connect the single output of the multiplexer to the GPIO input.

[@OneComputerGuyWorking]

The best intro that I've ever seen in the series. Love the show :3

[@JamesSkemp]

The beginning of this episode made me realize how much Felix has changed in front of the camera; he seems more confident in front of it, which is awesome to see.

[@ryanamberger]

Glad to see more Felix. Theres a lot of knowledge between those two. Feel smarter after every video.

[@laynesamba]

Excellent episode!

[@dudesky1325]

I like this style of video, stuff like this happens to us DIYers (or maybe just me) somewhat often. Good to see some solutions and ideas on how to work around problems from guys that do this kinda thing all the time.

[@flybywire5866]

Good to see more of Felix!

[@xxlaze44]

Felix is such a cool guy, I hope we can see him and Ben working together more often.

[@brucewayne-px4lv]

that formlabs printer is a very cool machine.. Ben is going to make some really cool stuff with that. I can't wait.

[@Kadjius]

I haven't seen the whole video yet, but look at how happy Felix looks in the intro! :)

[@willofdodge1]

Can anyone tell me what programming languge Ben is using @10:19 It looks like C but I cant really tell

[@bsb0011]

Second time they have eluded to a charge controller for the Li-Po batteries, but where do we find the actual schematic for it? I've been looking for a charge controller to use in my own projects, but I have only found chips that use some almost BGA type surface mount connections. What hobbyist has time for that junk?

[@TheMBB99]

So nice Intro. Thanks again for this wunderful episode :)

[@r0neko]

Hi Ben.Can you build a Raspberry Pi Carkit that can do the following: Receive calls,Send Calls,speak caller id info,Send SMS,Recive SMS and speak SMS info.Thanks.

[@jastervoid]

Would have liked some footage of the new printer printing.

[@izzykogan]

great video as always Ben

[@IceBlokee]

would it have been possible to use a tilt sensor for the orientation

[@zaneyoumans2923]

I love it when Felix gets his own little segment

[@jerviservi]

Felix deserves more love. LOVE YOU FELIX!!! I WANT TO BE ABLE TO PROGRAM LIKE YOU!

[@GryffDavid]

Kinda glossed over that 2S LiPo charging circuit. Looking for that exact thing, any chance of getting a schematic?

[@Felipera_]

I remember watching a ted talk about that 3d printer technique a while ago. I'm glad it's catching on.

[@jet_flyer]

15:19 The Ben Heck Show do you have the schematics for that circuit? planning for a solar plane project that might be useful

[@Fordi]

I know this is old, but did you ever finish a CM variant? I'd love to take your Eagle files and finish this off myself; I've got a CM3 I'd like to put to good use. [Edit: found them on Element 14; I just want to know if the files have the errors with respect to the masking fixed, or I'll need to fix 'em myself. If it's the latter, how can I send them back to you to update?]

[@Felipedotcom]

This is so cool man. I would love to have a fully customizable calculator (customizing even the OS).

[@JamesSato]

Love Felix! More episodes with Felix's work please!

[@aidansciortino982]

Any odds that the PCB will get released to the public? If so where would I find it?

[@alecblumenfeld]

felix why did you need to enter the qty of operations, why not use a stack?

[@milky1234123]

What is the name of the song you used at the beginining of the video i must know

[@adamjezek98]

What IDE is Felix using in 10:39?

[@89packman]

hello is it possible to use just a touch screen instead of the key pad ?

[@themaconeau]

Does anyone know what PCB package Felix uses on linux?

[@Valentino_Mrtz]

Is it possible to get the circuitboard for the keys?

[@jasonteknut]

Adding a multiplexer and a polling software loop seems needlessly complex and possibly introduces poor response time. Why not wire the "down" button to trigger "left" and "right" at the same time and tell the system that left and right at the same time is a down? They are mutually exclusive by nature of a joystick.

[@orektez]

I have a vtech laser 50 I love pulling out when someone asks me for a calculator, always fun to see their faces.

[@orinokonx01]

This is awesome. I want to build this!!! Felix, is this code going to be put up somewhere for us to look at??

[@WashashoreProd]

Now... it occurs to me that you could have solved your input problem by using an Arduino Leonardo as a keyboard input. Can any of the smaller Arduinos do the same thing so the entire package doesn't become insanely bulky?

[@jacklewis6392]

Can I buy a set of plans for the fixed PCB?

[@charlesharrison8422]

Ben can you make a Nes clone system using the RaspberryPi, that actually loads carts rather than roms?? (similar to the retron 5)

[@SharifSourour]

I noticed you programmed in Java! That's awesome, and what I've been using.

[@allluckyseven]

Which camera is Max holding at, for instance, 8:00? The image gets blurry and it looks like "something" is trying to remove the shaky-ness. Is it an iPhone? A GoPro? Please stop using that, if possible. EDIT: Typo on the Tech Timeout: multiply -> multiple. Ben could try to make that kind of printer using a projector, huh? Like one of those people has been posting on Instructables!

[@chad7615]

allluckyseven That was annoying the hell out of me.

[@AlainHubert]

allluckyseven This has been "corrected" using KZbin's video stabilizing algorithm (optional post processing after uploading) which results in a supposedly more stable subject, whilst inducing nausea to the viewer and causing blurriness.

[@allluckyseven]

AlainHubert It does look like it, but why none of the other footage has this effect? My guess is they're using image stabilization software outside of KZbin and only for those shots.

[@AlainHubert]

allluckyseven You're probably right. But it looks like the same nausea inducing algorithm was used... lol !

[@maxximumb]

Can we get to see the new 3D printer in action. It would be nice to see how it works and the size limits for printing and so on.

[@StanislavJochman]

Can i get schematic of Felix`s charging circit

[@chrismurray9401]

That intro was just the best.

[@dsmandras]

Just out of curiosity, what OS does Felix use on his laptop?

[@TechByMattB]

To me this show how outdated graphing calculators are, usually when ben makes a DIY its huge in size compared to a similar item thats made with traditional manufacturing. Yet this is the same size if not smaller than the TI 83's of the world.

[@b4ux1t3-tech]

Does anyone know what Gedit plugin Felix is using to get the SublimeText-like code overview on the right @ 11:04?

[@b4ux1t3-tech]

Technicus Spiriticus ah, thanks!

[@jasonzacharias2150]

I like how Ben goes from disappointed for like two seconds before his brain completely reworked the design. If that would've been me I would've thrown the board at the wall and cried... Thanks for posting guys, God bless and keep you during the ultimate convergence in the matrix....

[@OriruBastard]

Ahh... It's nice to see Felix enthusiastic as ever. :)

[@frollard]

That's a pretty cool graphing adding machine.

[@StarDustSid]

I find this channel really informative and its inspired me to get back into electronics. I recently got a Raspberry Pi 2 and an Arduino Uno and I've been doing some simple projects. I believe it's possible to damage the Raspberry Pi by shorting the GPIO pins. Would it be possible for you to mention in a future video how to best protect from doing this, (other that checking your work.) Is there a simple diode and/or resistor solution to this problem? Thanks.

[@stephenjames2951]

Did they have to invent 3d printing first?

[@VoidMoth]

Stephen James no silly it was already invented, everyone has those, they are like the next technological step from the nail and hammer

[@Adryyy]

r/whoooosh

[@jarrettquincel2287]

What kind of Linux OS are they using on the laptops. All I know is its Linux based but its not Ubuntu.

[@jgj4430]

The Ben Heck Show is it possible to build a graphing calculator that can use the Texas Instruments OS?

[@kennytheamazing]

Man, I really need something like this.

[@Minwater5]

I'm new to electronics and programming. What program did you use to program and what language was it?

[@Minwater5]

***** thanks

[@tmacedo29]

Maybe I didn't understand well, but the code inside the for ( columnCount = 0; columnCount

[@mirabilis]

Actually 6 0 1 2 3 4 5

[@RJiiFin]

Thiago Macedo Beat me to it! :D

[@EpicFandi]

Damn the pre-intro was hilarious! :'D

[@BrentBlueAllen]

I wish we could've seen the Form 1 in action in this episode.

[@vanwaestel]

You should not be connecting lipo in series and charge then this way. I would make charging board charging each battery separately. Same as every RC battery pack!

[@bartz0rt928]

more capable and possibly cheaper than a real graphing calculator! Any plans to make a kit out of this?

[@PDRIFT86]

Overall i think it's awesome but that power jack on the back though.. Why put it there?

[@HighFlyActionGuy]

You guys should use AP Circuits for 2 layer boards with silk screen and solder mask. Delivery time is 4 days, and they help you catch mistakes like the solder mask issue mentioned in the video.

[@sknt]

The placement of the charge jack is... creative... :)

[@ihsaanyasin7132]

Could you please make a video of a new 3ds xl and Ps vita combined thanks! :)

[@hanro50]

I wonder if you could make a calculator, a portable com device(hidden in the calculator ) in one build, say you switch it to com mode bay hitting = 3 times and then it works like one of those old cell-phones keypads

[@Pancreaticdefect]

What the hell is going on with the camera during the GPIO joystick whiteboard part of the episode? It's a good thing I dont have epilepsy.

[@CallumWK]

all you have to do is run a notepad on it, and write down all of the exam answers, then take it in the test with you. mwahaha

[@joseyanez2342]

Is it allowed in test?

[@LinkTheKiller13]

To bad couldnt use the custom circuit board ot looked great but the project atill looked really cool and good. Maybe use a lower profile switch for the power switch? But over all it looks great

[@linuxgnuru]

Is the source code available?

[@AM-cd3kn]

Felix is the reason the other side of your pillow is cool

[@doriphor]

I wonder how many people other than me suggested a graphing calculator :) Nice, and thank you!

[@pac85]

The stick with four buttons was really easy to fix : you use one input which is low when down is pressed and high when is not, you do the same for left and right and finally a third button which is low when none are pressed.

[@gbraadnl]

22:18 Floating point exception It runs Linux on the Pi, so you could run any graphical environment to have a full graphing calculator app running. Many can run from xfce or fvwm.

[@gaming-zombie1392]

An other Great video thanks Ben...

[@robotwo]

Using integers for a calculator seems pretty weird. Wouldn't you want decimal point precision? And while not optimal for memory management it would've probably been more user friendly to have a dynamically scaling array for the numbers and opperators, as it's not always certain how many elements you'll need to enter beforehand. All in all it's a really neat project. I think I'll keep my Ti-84+ though :)

[@Paranoidhaze]

We want an episode with a 3D printing project on the new printer!! :O

[@burkantorun]

You could use 1 analog input (if its avaible on the remaining gpio's) and 5 resistors for the joystick instead of mux. but this version is equally educating for newbies.

[@Papperlapappmaul]

Your "multiplexer" is actually a decoder. A multiplexer has n² data inputs, n select inputs and one output. The binary value on the select lines will determine wich input is send to the output.

[@krinistof]

"Hey! Linux runs on my calculator, and if I want I could make a file server on it :DDD" Soooo badass !! Good job.

[@iiizzak]

Hi ben can you plz do a project useing chip?

[@wclifton968gameplaystutorials]

isnt it easier to just use a USB Numpad wired to the SBC with a touch screen with the num lock key on the numpad wired to be an equals key instead?

[@TriponMihai]

I guess you could replace that power on/off button with a tach switch that runs a program for powering off the system and another tach switch for power on the system. If you power-off the system through " shutdown" command and then you short the reset pins, near the display port the system will power on :) I use that on some expansion boards at my job ;)

[@Gamewwx]

that would be so cool build

[@Mr.ShyGuy96]

Can you make a how to video on making a Nintendo 3ds/2ds Gamecube controller adapter? It would be the first on youtube and it woukd be so awesome!!!

[@johanndirry]

I would put a big touchsrceen on that basically how the HP Prime does it.