Controlling Mechanical 7-Segment Displays?! How RS-485 and UART works! || EB#43

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In this video I will be having a closer look at commercial mechanical 7-segment displays and find out how they work. Afterwards I will be creating a KZbin subscriber counter with them and an ESP8266 by not only finding out how the control PCB for the display works, but also by learning about the RS-485 and UART interface. Let's get started!
Thanks to Alfazeta (flipdots.com) for sponsoring this video!
Music:
2011 Lookalike by Bartlebeats

[@pauljackson2126]

That sound of listening to mechanical clicks of these displays and even hearing the clicks of relay array is always a pleasure to hear🙌

[@sarmadrafique4472]

More like a therapy.

[@joinedupjon]

Yep I'd be looking for excuses to add needless extra segment flips just to make it click - non numeric spinning wheel effects etc.

[@reggiep75]

Poly-rhythmic relay click patterns are enjoyable to hear.

[@bexpi7100]

if you want to see some mechanical display + relay awesomeness, proto g engineering made a cool thing: kzbin.info/www/bejne/qZyQkK2wpNuAfbs

[@MrQuanticox]

here is more: kzbin.info/www/bejne/qZyQkK2wpNuAfbs

[@sikkepossu]

He's getting more and more insane with that "I will see you next time" thing. :D

[@ArnaudMEURET]

Those punchlines gimmicks are usually the last straw that pushes me to unsubscribe when a channel’s content gets repeatedly disappointing... Not that it has been the case yet with GreatScott but I still would love if he got rid of that annoyance ! 🤯

[@PassiveDissimulation]

Arnaud MEURET I think it’s funny! At least it isn’t the same every time. It’s his catch phrase.

[@josephhacker6508]

This video isn't sponsored by JLC-PCB

[@Rainbow__cookie]

Reality is often disappointing

[@labiadh_chokri]

This video is sponsored by ALFAZETA

[@josephhacker6508]

@@labiadh_chokri It doesn't have the same ring to it.

[@hardikmonga]

Boring without JLCPCB commercial 😂

[@anonymouspuppy]

Hardik Monga I know

[@ZevHoover]

I can’t be the only one who starts twitching slightly every time he runs the highlighter over the black pen enough times that the black ink starts to run. Love your videos though man.

[@glennlawrie-smith8570]

Zev Hoover Yup.

[@glennlawrie-smith8570]

Zev Hoover Yup.

[@DarkThanosGr]

I scream NOOOO every time!

[@TheInCaver]

True!

[@gglovato]

ajjaja me too

[@izzieb]

These kind of displays always remind me of the old clocks and departure boards in Britain, under British Rail.

[@CTCTraining1]

Yes, I wonder which rail enthusiasts managed to nab them. They used to make very solid clonking noises indeed.

[@izzieb]

@@CTCTraining1 I'm sure many did. I have fond memories of the old boards at places like London Bridge, making the distinct sound as the boards updated.

[@SheeplessNW6]

@@izzieb those departure boards are called 'split-flap' or 'Solari' displays, and there are at least a couple of companies who will sell you a new one. Well, I'm not sure whether Vestaboard ever stopped being vapourware, but Oat Foundry are certainly shipping. If you google for 'split-flap display' you'll find various hobbyists who have made their own!

[@samuell.foxton4177]

The station clocks in the UK were these, not split flaps

[@lemonglataitor2123]

How to stress out children taking a timed exam.

[@greatscottlab]

Haha true :-)

[@AnthonyGoodley]

Lol that's funny.

[@girishradhakrishnan2699]

Lol

[@Glasshopper]

Very funny 😂

[@rich1051414]

Gradually increase the volume, but slow enough to make the kids think they are going insane :) This is why I am not a teacher... the kids would need professional help after my class.

[@hackerman7835]

PRICING FOR OCTOBER 2019: 7 seg modules: 9 EUR apiece for 1-99 pcs controllers: 21 EUR for 1-99 pcs 190 EUR for a bundle of 1x10 digits with controllers

[@marcinpkrysinski]

hackerman 7 Seg is 6.50 EUR for any qty...

[@marcinpkrysinski]

Solitary Midnight for limited time they sell any qty for 1000+ price which is 6.50 EUR

[@dwild92]

@@marcinpkrysinski any quantity 1000+.... Yeah that's not any quantity if it's over a quantity.....

[@Nathan0A]

I don't know why, but the highlighter smearing your ink really bothers me on some fundamental level. Great video though!

[@martincerny3294]

He does this on every video, it's triggering lol!

[@PabloAymerich]

And to get a price you have to ask for a quote. :( why couldn't they put at least an MSRP or estimated price per digit? It would be good for them to offer a DEV kit for $XX dollars with 4 digits and uart board?

[@sarkybugger5009]

_If you have to ask, you can't afford it_ is the usual approach of companies like that. Screw them! They must be out of patent, so I'm sure there's a factory in China churning them out by the thousand, for a dollar or two a piece.

[@PabloAymerich]

SarkyBugger I felt that way exactly

[@StephenHoldaway]

Search for "ebay Ferranti Packard" on Google - I found it slightly cheaper to buy new-old-stock or used original displays. Alfa Zeta is manufacturing new stock of an existing design which is great for industrial customers, but for hobbyists the supply chain aspect doesn't matter. When I got a quote from Alfa Zeta in 2018, it was cheaper per unit to buy a dozen on ebay including shipping than to buy 500 new units.

[@hackerman7835]

to quote another comment: The pricelist i got when ive asked was 9 Euro for a 7 Segment without controller (as shown in the beginning) 24 Euro for a single digit controller (didnt ask for code to controlle it, wanted to use it as a base for my own design). And the Simple flipdots were from 4-12 Euro available. Just mail them, the reply was fast and informative when i asked some questions reguarding shipping and price. Hope this helps. Their page also shows some cool Projects they did with artists.

[@beware_the_moose]

@@hackerman7835 at those prices why don't they just put a PayPal button on or something! I'd buy!

[@lptf5441]

I really want to commend you on a particular detail of your videos... the time and effort you take, as a non-native English speaker, to slowly and clearly pronounce each and every word in your video. So many videos from people who are non-native speakers of languages are almost unwatchable because of how difficult it is to understand what they are saying. They have poor pronunciation, they mumble, and they speak way too quickly. It can be hard enough for some native English speakers to understand other native English speakers from different countries, but non-native speakers are other level of difficulty. However your efforts are absolutely wonderful. All your videos are very easy to understand. Thank you for making the effort.

[@jagadishk4513]

Hi Scott, I am debugging an RS485 design-driven by raspberry pi, before coming to this video I was tired upset because it was not working and it was 3AM in the morning. In your video you mentioned that the baud rate must to matched, then it dawned upon me that I must modify it and it worked. I guess when your frustrated you mess up even the most trivial things. Your video gave my cluttered mind a hint. Thanks a Ton, Scott, never stop making these videos.

[@davidadams421]

Absolutely brilliant - glued to the screen! Your patience and commitment is inspiring.

[@StreuPfeffer]

Ive found the company a while ago through another YT vid. got myself a couple 7 Segments and some flipdots. Also got a single RS485 segement, didn't get to them unfortunatly yet. Thanks for makeing it more clear how they are driven though.

[@MrKugelkopf]

How much did you pay for it? And is there a shop?

[@felixwurm1467]

i think you have to contact them

[@StreuPfeffer]

@@MrKugelkopf Just contect their [e-mail] email address. The pricelist i got when ive asked was 9 Euro for a 7 Segment without controller (as shown in the beginning) 24 Euro for a single digit controller (didnt ask for code to controlle it, wanted to use it as a base for my own design). And the Simple flipdots were from 4-12 Euro available. Just mail them, the reply was fast and informative when i asked some questions reguarding shipping and price. Hope this helps. Their page also shows some cool Projects they did with artists.

[@MrKugelkopf]

@@StreuPfeffer thank you!

[@amirreza6526gd]

thanks a lot for talking about the RS-485, I wanted a simple with example video about RS-485 and your explanations were the best.

[@stevenmorisset4307]

10 digits will never be enough for you GreatScott !

[@graphenepixel8231]

Billions of subscribers

[@GRBtutorials]

Yeah, when the human population reaches 10 000 million, he will need an extra digit. Until then, it’ll be good enough.

[@vectorchan5647]

Hopefully china starts making these. I'm not buying from a company that won't tell you the price without "getting in touch with a representative"

[@g00st62]

Thats basicly just another way to say "way to expensive for you and dont even try to buy them if you dont need at least 5000"

[@hackerman7835]

someone ITT commented the following: Just contect their [e-mail] email address. The pricelist i got when ive asked was 9 Euro for a 7 Segment without controller (as shown in the beginning) 24 Euro for a single digit controller (didnt ask for code to controlle it, wanted to use it as a base for my own design). And the Simple flipdots were from 4-12 Euro available. Just mail them, the reply was fast and informative when i asked some questions reguarding shipping and price. Hope this helps. Their page also shows some cool Projects they did with artists.

[@doublebulbing]

@@hackerman7835 they are cool but too pricey just to buy to play with

[@geomagpsz]

I'm afraid that most of the times it works this way with industrial products :/ every time I have to do research to purchase components for a project is the same, I have to send s thousand emails asking for quotes (Usually they answer back with a huge price xD)

[@andrewkieran8942]

Another great topic, but I missed something. In one of the the diagrams, one end of all of the magnets in a digit are connected to a common source, and the individual segments are grounded by a darlington transistor pair. How do you switch between the two states; segment displayed or segment not displayed? Removing the power retains the existing state so don't you need to apply the power for state 0 and reverse the polarity to select state 1? How do reverse the polarity in this case without an h-bridge?

[@raykent3211]

Me too. I guess he used Darlington pairs to drive leds that needed more current than an ordinary logic chip can provide and he guessed that this was done here. But, as you imply, current can only be passed in one direction through a darlington pair and the muxing won't work. Most likely there's a number of mosfet H-bridges involved. There's a lot of chips on that driver board!

[@valshaped]

You might be able to get away with pulling the common line high and pulling only the electromagnet you want to load low? I'm not sure.

[@danielvalle3789]

Pondered the same thing! Figured I missed something (which, I obviously did but still happy I'm not the only one lolol.)

[@otm646]

We use a large 3 inch set of mechanical displays on our racing sailboat for important data. It's excellent, low power and most importantly doesn't have the visibility issues like LCDs with polarized sunglasses. Old tech but still the best in some applications.

[@alanm.17]

This could’ve made a really bad ass 80s dashboard speedometer

[@anycatdessai]

Liked the new fusion way of project and electronics basics video in one. Makes it quite interesting.

[@greatscottlab]

Thanks for the feedback :-)

[@sjm4306]

Alpha zeta is great, they sent me some displays to make a sub counter with as well. I designed my own controller as I wanted a challenge and ended up open sourcing the design.

[@Miata822]

OK, that's pretty cool. It just seems to me these displays call out for an analog driver. Thinking about how to do that.

[@Gideon_Judges6]

This is some heavy artillery compared to just a 4511 or similar 7 segment decoder, but then again you would need multiple (10x) plus some kind of transistor as I suspect those coils draw more current than the typical LED seven segment.

[@graphenepixel8231]

I thought the same thing.

[@engineer0239]

Funny. I worked with Modbus Commands sent from a PC that got converted to RS-485 in my holyday job. I was controlling an Axis that moved a camera for Image recognition. I was coding an UI for it and now you´re making a video about it. Nice.

[@MikeysLab]

Love this display, but the companies site does not have pricing or a way to order :( would love to use these in a project on my channel.

[@dj_paultuk7052]

RS485 used to be really handy in the pre-wifi days as you can run it really long distances with no loss of signal with a data speed of 115k. A company called Lantronix also sell a Ethernet to RS45 server device (UDS10), so you can drive RS485 on a ethernet based network.

[@resneptacle]

Still being used in the show and theater industry for the DMX lighting protocol

[@alpagutsencer]

The soul of the Marco Reps is in us.

[@Clark-Mills]

First saw the display and thought... I could optimise that code by storing (buffering) the state of every segment and then just flipping the segments that have changed. Then I look at 4:06 and realise that the code is already optimised. Nice.

[@romandirscherl151]

Please Upload a Video in Twitter where i can hear the clicking sound It sounds so awesome

[@greatscottlab]

There already is one on twitter.

[@paulturner5769]

That doesn't explain how the drivers supply reverse voltage / current to the segments you want to turn from ON to OFF though.

[@popcorny007]

Presumably that is handled by the controller board. He is just programming to get a serial output.

[@paulturner5769]

​@@popcorny007 I was referring to the explanation of turning segments ON at 2:58 to 4:03, It is NOT like multiplexing LEDS which turn OFF when there is no power, these segments retain their state until power is applied in reverse.

[@labiadh_chokri]

Yes every segment must have a H bridge or be connected between tow Logic output that can source and sink the appropriate current .

[@cabasse_music]

your vids are the best, man. can't believe i hadn't found your channel sooner

[@Gamezone-sd3er]

Well I can use it as notification for great Scott video upload

[@greatscottlab]

Correct :-)

[@theteenageengineer]

The control board seems a lot like a DMX controller for entertainment industry lighting, big Clive has some great videos explaining it. But DMX uses RS-485 to be able to control up to 512 lights and the 2 RJ-11 ports on the controller board is where I got this connection from because for DMX there is always 2 ports on each light so you can connect multiple in a chain.

[@Enigma758]

With source driver common to all electromagnets, and sink driver to each segment, it's not clear how the coil polarity reverses in order to reset (darken) the segment.

[@geomagpsz]

I've just unsubscribed and subscribed again just so you could hear the noise of it. Now it's time to do a cool enclosure for it with neopixels ;) Keep up the good work and smooth editing. Your channel is really fun to watch and inspiring! Greetings from an electrical engineer in Munich :)

[@GRBtutorials]

Unfortunately that won’t work, as it takes a while for KZbin to process it.

[@sasodoma]

@@GRBtutorials Also, it seems to grab the public data, which is rounded to two decimals. In his case that's rounded to the nearest 10 000.

[@honzapat]

KZbin changed, you now need to be authed as the creator(some app in gcloud console probably) to get it precise.

[@pileofstuff]

@@GRBtutorials It also won't work because youtube now rounds off the subscriber number...

[@pileofstuff]

@@honzapat Even with your own API key, you can't get accurate sub numbers via the API. Only from the creator studio, which can't be pulled into a device like this.

[@ats89117]

It's a good thing they sent you a 10 digit display so that it can count up to ten billion subscribers. You never know!

[@MrJuuustin28532]

You are THE BEST at this out right now. Thanks for all your work. Awesome! 👍

[@AnthonyGoodley]

When them new fangled 7 segment LED displays are too high tech so let's take it back old school.

[@AnthonyGoodley]

Like I think these are very cool and all but it seems like a lot more work to get working as compared to 7 segment LED's. Reminds of those Airport displays that click to show arrival and departure times, gates etc.

[@rafaswierczynski]

So cool those displays :) As always - nice video! And sound of switching.... lovly...

[@kirbymia6209]

This is pretty interesting especially since we just started messing with USART for our microprocessors course. I might make one of these some time.

[@crazyivan030983]

And now you have red "black" highlighter... :) super video :) greetings from Poland :)

[@unperrier5998]

The three digits on the right hand side (lsb) mechanically switch more often and hence will wear before the most significant digits. They must have thought of that and allo you to replace them or swap the 3-digit module with the msb one.

[@brane3698]

segments have no mechanical linkage, they are controlled with electromagnets, so there is nothing to wear out, at least not that soon...the manufacturer states segments are rated for over 250 million operations

[@unperrier5998]

@@brane3698 250 million operations, that's plenty but it's probably less due to dust and dirt.

[@unperrier5998]

@oH well,lord! if you prefer.

[@arthurbondar4881]

no need for multiplexing, a simple shift register and a couple of latching ICs will allow you to connect any number of those displays...

[@Loundre3]

What about the drivers for the electromagnets?

[@arthurbondar4881]

those too ofc

[@agarceran]

I personally preffer the look and sound of the Split-Flap displays, but this looks interesting and are quite a lot simple.

[@StickySli]

I'm currently learning how the USART works in the Atmega328p in my ICT Engineering degree. The catch is we're learning to program the microcontroller in Assembly. We've yet to learn C and other languages. Assembly is pure masochistic.

[@bharathr2871]

More than college education your channel gives me more information.

[@IvegaEletrônica]

Muito legal esses displays.

[@derekchristenson5711]

Neato! Thanks for showing this in action.

[@arduinohub5957]

I will use some multiplexers and transistors to drive this (without understand the whole mess) :D

[@sligovolts]

It's a lot harder than it sounds. Look up on KZbin, there's some videos of EE driving similar dot matrix displays

[@260830107]

to flip a segment it needs a >200mA pulse in 1 direction and un-flipping needs a current pulse in the opposite direction, you'll probably need something that has a push pull output

[@ash0787]

Your videos have been very useful for me GS so i'm gonna tell you about a problem / project i've been working on... since I started studying electronics a year ago i've wanted to reverse engineer a mobility scooter / electric vehicle ESC, its a DC brush motor which is controlled by a single potentiometer which controls reverse, forward and braking, the trigger seems to act as a desired % of maximum speed, and the vehicle automatically accelerates or brakes to meet that % target. The boards seem to utilize a microcontroller, I would like to implement a similar system without. Firstly I am trying to make it so there are 2 pedals, brake and accel which will each give a 0 to 5v signal lets say, this is then compared to see which one is higher, which activates either braking or accel mode.... there will be two 555 timers creating the duty cycle for power or regen braking seperately depending on the pedal signal intensity. The issue im struggling with right now is trying to control the PWM duty cycle of 555 timer using just a single 0 to 5v voltage ( not a potentiometer ). My idea is to use MOSFETs to control the resistance of the charge / discharge portions of the 555 timer operation, but im having trouble fine tuning it so that the mosfet works properly as a variable resister, I have to compress the voltage into a confined range of about 2v to 3.6v it seems.

[@andymouse]

I must say, those displays are quite charming.

[@aisaya-ana]

Very Nice. Also your explanation lead me to understanding another things as well. Thanks.

[@jamest.5001]

Kinda cool retro style tech, reminds me of the old alarm clocks!!

[@dieterdodel5265]

Machst Sehr gute Videos. Einfach erklärt. Gefällt mir sehr💪🏽

[@Uko_]

I think you forgot to explain the ground reference problems of RS-485 or UART. For example, the maximum common mode voltage of A and B inputs, when to use isolator, and so on. Basically, the ground connection in differential signals .

[@andrejwalilko634]

Scott is now limited to less than 10 *billion subs

[@SlykeThePhoxenix]

Well obviously he's gonna drop the LSB when he hits 10 mil.

[@tomf3150]

More like 1.999999 billion.

[@reggiep75]

6:55 - This is like the XLR standard in the music industry for professional balanced audio facilitating levels of noise removal. People think 'Hmmmm' to begin with and then 'Aaaahh' when they understand the process of the inverted signal to isolate the noise and then remove it from the final signal.

[@JDanielGamerXD]

And don't forget that stage lights use XLR too

[@reggiep75]

JDanielDroiidXD - Depends on your pinout (anything from 3-7) but the good thing about XLR is it's scalability lending itself to a shit load of functions :-)

[@galier2]

The twisting of the cable was not really necessary. We used it always on flat cables with 15 Pin D-SUB connectors with speeds up to 38400 without ever having any issues even in hostile industrial environments. The only important thing is that the differential data lines are not too far appart so that induced noise is the same on both lines.

[@graphenepixel8231]

I love that sound.

[@mathiasbackof4993]

Oh man finally a real thumbnail

[@keithking1985]

I have to say it is satisfying to look at.

[@jansaljaj3042]

They are probably not driven that way because of coil resistances which would activate other digits. Watch Marco Reps's video about his clock, he had this problems.

[@pjshots]

I need those things in my life! So functional and direct.

[@moclan582]

Hey, wich Multimeter do you currently use? Would you recommend it? And do you maybe have a recommendation for a meter for around 100€?

[@danielvalle3789]

Orrrr, ....just tell the man!!! Somebody need a snickers perhaps???

[@danielvalle3789]

(

[@moclan582]

@@danielvalle3789 ikr I can't find the video

[@diyexplorer8728]

I want to use this as a clock on a school library. Great video!

[@sentien13]

I use RS485 basically daily, the moment I saw you writing code for the Nano I was instantly going 'nope, nope, nope, nope!' in my head. Whilst I fully understand the difference it would have been useful to explain WHY the Nano does not support the 485 standard.

Vince Osborn I am also curious about this.

[@wtf6892]

Thank you for making this kind of videos it's priceless!

[@BlackXeno]

Time is gone when I could see 10 minutes of GreatScott without additional 2 Ads in the middle...

[@popcorny007]

At least be happy he can find such extremely relevant sponsors. Imagine him being supported by Blue Apron...

[@tushar673353]

you did really lots of work on this project

[@yeahitworks]

Love these mechanical display... I'm working on a project that needs a bigger display, 10" - 12" height. Any recommendations?

[@shrikantnikam2426]

Next video plz ....Explain HID microchip device communication with application with practical example

[@stjepansavic4485]

That sound for mi is beautiful

[@ZeroMass]

Another interesting video. I look forward to your uploads 😋🍺

[@greatscottlab]

Thanks :-)

[@dr_stoned_4207]

Finally a new sponsore!!!!!!!!!

[@rif6876]

Curious, how many attempts did it take before working properly. And do you remember the mechanical display that flips through the numbers? Also a very satisfying sound

[@thexpto51]

Very good! Really Nice Work! Congratulations!

[@AmeshaSpentaArmaiti]

They look really nice

[@anyfinity]

1:48 - 1:52 that's a great idea!

[@andrewhamop6665]

Are we going to see the subscriber counter in videos from now on? I think that would be an awesome idea!

[@giotinez5996]

I learn a lot with ur videos even many of them are for avanced dudes. Thanks brother

[@cquiles386]

I hope you make a video of you making a custom enclosure for this!

[@bobsort]

RS-485 is similar to RS-232 which is a communication protocol. en.wikipedia.org/wiki/RS-232 and those segments are controlled the same way memory of early computers like IBM-370 worked. en.wikipedia.org/wiki/Magnetic-core_memory

[@sumantacm1]

Nice video Scott but I was more interested in large size led seven segments... I am miopic and was planning to build a large size digital clock so even in the middle of the night I can see time without searching for my glasses first... Can you please suggest me where I can get those...

[@KJ7BZC]

That is an awesome display, I think that there are even dot matrix displays like that. Just curious, is it possible to use a regular arduino with an Ethernet shield to monitor subscribers? Instead of using an esp8266 that is.

[@zaprodk]

Yes and Yes.

[@KJ7BZC]

@@zaprodk cool

[@sarfarazsheikh5448]

Thank you for useful information My next project And I facing some problems with my project DIY stair case light using pir sensor and arduino

[@EasyElectronics2412]

one of the awesome videos i have ever seen!!! :)

[@srinivasraor770]

That was amazing project you took scoot i just loved it.

[@horashia495]

Oh my god I couldn't understand anything I'm so confused and I feel stupid I wanna cry right now ..but fantastic video as always

[@IvanStamenkovicSeemsIndie]

It's not you, the video is way to messed up...

[@someguy4915]

@@IvanStamenkovicSeemsIndie It's pretty easy to follow, he explains what you need to know, nothing more to confuse etc...

[@horashia495]

Some Guy You probably already have an advanced knowledge in electronics thats why you and greatScott find it easy ... but for us the majority who are just interested but still in a beginner or intermediate level in electronics its very difficult to follow

[@Raismans]

Now we just need Nixie tube display control video :)

[@Jacobsonro]

Very nice video, do you know if these could be used with a openEvse?

[@haroonsyedmohammed8430]

Your videos will be exciting!

[@abhishekjoshi9274]

Great video ......try modbus using rs485

[@lukaszpodgorski]

Great Video Great Scott

[@sebrassino]

I really have to follow a study of these electronics. Don't know i2c. The way to code it. Just those things would make projects a 1000 times easier.

[@d23rfd3gfjhjhgfdze]

This channel should have more Subs.

[@DIYPINOY]

Great project. Great scott

[@richardlighthouse5328]

RS-485 is an electrical standard. In your case RS-485 electrical standard is combined with UART protocol.

[@sinfulf4i]

ohhh that was soo cool need a clock made like that with the secs displace clicking away

[@jcgo16]

The sound that it makes so.........gooooooodddd

[@s.sradon9782]

Can you cover VFD dot matrix displays please? They look cool and are a very strange type of electron valve.

[@greatscottlab]

I can put it on my to do list

[@s.sradon9782]

@@greatscottlab Thank You!