You completely skipped over one important detail: Dimming! Your explanation only shows how to switch the colors on and off, but how did you dim them? Pulse length for every LED?
For a Charlie plexed cube you can only have basically one LED lit at any point in time, you just have to very quickly loop over all the LEDs that need to be lit and give each one a small windows to be visible. Then rely on persistence of vision to make it look like they are all active at once. To dim an LED you just need to turn it on for less time or skip it for some update cycles. You cannot use PWM for this, each pin needs to be controls many LEDs and it is toggled in a non regular period. Note that because of this all the LEDs are quite dim to start with as they are only ever on for a fraction of the time.
This question also came to my mind as it was one (of a few) issues that I also could not solve when I attempted to build a LED cube 10 years ago using a Raspi of the first gen. I also hit the activity flickering issue, but could solve it with OS priority settings (was about to switch to Realtime Linux at a later point for higher reliability). In the end I was unable to solve that dimming issue as with higher "framerate" to simulate PWM (or rather BAM) modulated dimming I got stuck with some sort of "phantom" issue, where the previous LED I had active was not turning off fast enough. Until today I could not solve that issue but I still have learned one bit or another over the years to undertake a new attempt, if I had the time nowadays 🙂 Great project and explanation!
So in the code, there's a bitmap where each LED is assigned a value between 0 and 255. Then I have a pwm_counter variable that goes from 0 to 255 and the back to 0. The actual function to light up the LEDs cycles through each LED/spot in the bitmap. If the value for the LED is greater than the current value of the pwm_counter, the LED gets lit. After all the LEDs have been cycled through, the pwm_counter increments by 1. Then of course if the pwm_counter is greater than 255 it loops back around to 0. In this way, I can control how many times any LED is lit in 255 refresh cycles of the LEDs. Hope that makes sense. I'm kinda fried at the moment😅
I have only ever idly thought of doing this, and trust me, I would probably have never done it, but the thought has helped me stay awake a night or two. This is freaking awesome, and I don't know how you don't have a ridiculous amount of views by now. You have scratched an itch by brain had but could not provide the spoons for. Thank you.
So fun to watch again! I remember when these first came out, just a few people over the world got one that they built in like a month or so.. I wanted to build one, I probably could have, but never got around to do it. But really great fun to watch one again, I love these! Great job and Great video! ❤
I made a 16 x 16 x 16 led cube. Thats over 4100 solder joints once the bottom plane is attached to the board, and the wires are run to each plane. So ya, thats alot of soldering. And a lot of set up for each, and then debugging was not alot of fun. But it did turn out very cool.
Yeah...but I had to do over 500 so like... we both had it equally bad. JK 😂. 4100 is insane! That must have been so satisfying to have all that work pay off.
3:16 You could have made it a 19*20 matrix and not use an extra multiplexed part, wiring would be a bit harder, but still doable, because you can just split the 20 to 15+5
Is this because it was 2020 and you could not get any parts at all to do this the right simple way? A simple ws2812 string requires one pin for all leds..Or the PL9823 leds that are not smd
Yeah some programmable LEDs would have been easier. At the time, I was trying to make it for as cheap as possible, which I think caused me to turn away from programmable LEDs.
For an American, you have quite an Italian body language ;-) Looks _really_ great, thank you very much. I think making this cube somewhat larger would make it look even better… I looks rather dense, these LEDs are so strong that they would optically still work fine with more space around them - and make soldering somewhat more ”pleasant“ (if you can say so for 500+ soldering spots ;-)
@@mal2ksc Yes, I already saw that ;-) I know that it is already an awful lot of work, but investing the additional time and material would be beneficial for the project. There are some guys here on TH-cam presenting this as a kind of “artistic light installation”… And to have a whole m3 of it in the middle of your living room makes it really stunning. I myself hate this kind of never-ending work and try to avoid it, but if somebody even goes this _extra_ mile… ;-)
😂😂😂 Can't say I've ever had anyone tell me I have Italian body language before. Thanks?😂 If I were to do a larger cube (like a 10x10x10), I'd have larger spacing for sure.
yeah guess every maker tried to do some real time computing on a raspberry at some point, for me it was a remote controlling a rc paramotor over wifi or bluetooth but as you found out too, constantly getting your code interrupted by an OS can be a real pain :D
this is the standard arduino setup...charlieplexed... ive still got my 4x4 cube sitting here i built in 2014...(i would have made more but..didnt have the leds on hand) you should really be using transistors on each row to power the leds otherwise you can burn out the mcu's gpio pin circuitry... ...you almost have a nice grid there to be able to make letters, numbers and symbols on the faces....
Indeed a weird way to make an led cube. You sure are original by making a 5 high instead of a 4 high cube, the 4 high makes for very elegant charlieplex wireing. The teensy 4 is way to powerful and expensive for this. A couple of transistors/mosfets and multiplexing combined with chalieplexing on the esp32 to reduce pins would have made more sense maybe?
I don't think I considered using a multiplexer. I've never used one before. Would you be able to set the outputs to high, low, and high impedance? Yeah the Teensy 4.0 has more power than needed, but it had enough pins and was only a couple dollars more than the only other board I knew of at the time that had enough pins-- the Arduino Mega. It does bother me a bit to use a microcontroller that has more power than is needed for the task. It's one thing that annoys me about the raspberry pi pico. The pico is so cheap that from a money perspective, it's the ideal choice for many projects. But many projects wouldn't take full use of its power. It hurts my soul to subject such a powerful processor to a lifetime of a simple task.
You save a lot of pins, but you can only light up a single LED at a time rather than an entire row, reducing brightness significantly. Additionally, it makes the wiring and code more complicated, and unintuitive. Generally, I don't think the tradeoff is worth it, when both microcontrollers with a higher pin count and shift registers are cheaply available. Soldering a LED matrix is already annoying enough with conventional multiplexing. An Arduino Mega, for example, has more than enough pins for this purpose, and the clones are cheap.
Thought the same, its unneccessary complex design bringing unneccesary drawbacks. Just shift reisters for the colums and you can live with using 8 pins for a 5x5x5 matrix
@@flipschwipp6572 It is just a proverbial "thought experiment", the world gets pretty boring when everyone always converges on what, at the time, is optimal. No different than the guy who calculates pi with relays.
Nice project, but where was the complex part? Turning the leds on by put them into a matrix is the most simplest way I know 😅 Why not using a adressable leds and set the color via spi dma which can run in the background of the mcu? Sounds way more complicated than a led matrix . And you can do other stuff with the mcu 🙂
It may sound more complicated, but if you do something like that, you’re probably going to use libraries for the software, right? This in theory can be done without all of that. Also, using ws2812b only requires one wire going through all leds, so the wiring is a lot more simple
@@fritzlb that is the complex part, not using existing Libaries some one already did. You have to read the datasheets, set the registers right. Especially if you have to read the reference datasheet, the device datasheet and multiple application notes to get all informations you need.
Only setting the registers isn't that hard or complex, also there are enough tutorials online for common architectures Completely bitbanging the ptotocol in asm might be a challenge tho
You completely skipped over one important detail: Dimming! Your explanation only shows how to switch the colors on and off, but how did you dim them? Pulse length for every LED?
just PWM, why not
For a Charlie plexed cube you can only have basically one LED lit at any point in time, you just have to very quickly loop over all the LEDs that need to be lit and give each one a small windows to be visible. Then rely on persistence of vision to make it look like they are all active at once. To dim an LED you just need to turn it on for less time or skip it for some update cycles. You cannot use PWM for this, each pin needs to be controls many LEDs and it is toggled in a non regular period. Note that because of this all the LEDs are quite dim to start with as they are only ever on for a fraction of the time.
This question also came to my mind as it was one (of a few) issues that I also could not solve when I attempted to build a LED cube 10 years ago using a Raspi of the first gen.
I also hit the activity flickering issue, but could solve it with OS priority settings (was about to switch to Realtime Linux at a later point for higher reliability).
In the end I was unable to solve that dimming issue as with higher "framerate" to simulate PWM (or rather BAM) modulated dimming I got stuck with some sort of "phantom" issue, where the previous LED I had active was not turning off fast enough. Until today I could not solve that issue but I still have learned one bit or another over the years to undertake a new attempt, if I had the time nowadays 🙂
Great project and explanation!
So in the code, there's a bitmap where each LED is assigned a value between 0 and 255. Then I have a pwm_counter variable that goes from 0 to 255 and the back to 0. The actual function to light up the LEDs cycles through each LED/spot in the bitmap. If the value for the LED is greater than the current value of the pwm_counter, the LED gets lit. After all the LEDs have been cycled through, the pwm_counter increments by 1. Then of course if the pwm_counter is greater than 255 it loops back around to 0. In this way, I can control how many times any LED is lit in 255 refresh cycles of the LEDs. Hope that makes sense. I'm kinda fried at the moment😅
I have only ever idly thought of doing this, and trust me, I would probably have never done it, but the thought has helped me stay awake a night or two. This is freaking awesome, and I don't know how you don't have a ridiculous amount of views by now. You have scratched an itch by brain had but could not provide the spoons for. Thank you.
Thanks! Love the expression " You have scratched an itch by brain had but could not provide the spoons for."😂
Awesome work!
The lightshow was mesmerizing to watch!
So fun to watch again! I remember when these first came out, just a few people over the world got one that they built in like a month or so.. I wanted to build one, I probably could have, but never got around to do it. But really great fun to watch one again, I love these! Great job and Great video! ❤
I never did a led cube but i feel the pain you went trough...
Write it bare metal in forth. There would be no flickering and the processor would have plenty of cycles available.
Wow, this is a really cool project. I cant imagine having to do that soldering job, good work :)
I made a 16 x 16 x 16 led cube. Thats over 4100 solder joints once the bottom plane is attached to the board, and the wires are run to each plane. So ya, thats alot of soldering. And a lot of set up for each, and then debugging was not alot of fun. But it did turn out very cool.
Yeah...but I had to do over 500 so like... we both had it equally bad. JK 😂. 4100 is insane! That must have been so satisfying to have all that work pay off.
3:16 You could have made it a 19*20 matrix and not use an extra multiplexed part, wiring would be a bit harder, but still doable, because you can just split the 20 to 15+5
Amazing work dude! Looks so pretty! Keep it up!
What you and most people today call "more difficult" was the standard on how the first cubes was made :P
I forgot I have epilepsy and woke up on the porch naked. My house doesn't have a porch. My name is Charlie so I guess I got Charlieplexed.
This is really dope
I would love to see you build something in a VIDEO- like set up a camera and build it!
Yeah 😂. That's definitely the plan moving forward, but for these first few videos, the projects were already done when I decided to do a video.
Excellent, David!
Is this because it was 2020 and you could not get any parts at all to do this the right simple way?
A simple ws2812 string requires one pin for all leds..Or the PL9823 leds that are not smd
Yeah some programmable LEDs would have been easier. At the time, I was trying to make it for as cheap as possible, which I think caused me to turn away from programmable LEDs.
For an American, you have quite an Italian body language ;-)
Looks _really_ great, thank you very much. I think making this cube somewhat larger would make it look even better… I looks rather dense, these LEDs are so strong that they would optically still work fine with more space around them - and make soldering somewhat more ”pleasant“ (if you can say so for 500+ soldering spots ;-)
@@mal2ksc Yes, I already saw that ;-)
I know that it is already an awful lot of work, but investing the additional time and material would be beneficial for the project.
There are some guys here on TH-cam presenting this as a kind of “artistic light installation”… And to have a whole m3 of it in the middle of your living room makes it really stunning.
I myself hate this kind of never-ending work and try to avoid it, but if somebody even goes this _extra_ mile… ;-)
😂😂😂 Can't say I've ever had anyone tell me I have Italian body language before. Thanks?😂
If I were to do a larger cube (like a 10x10x10), I'd have larger spacing for sure.
@@frickes_projects Don't worry, I like Italy - especially their excellent food ;-)
Have a nice day!
yeah guess every maker tried to do some real time computing on a raspberry at some point, for me it was a remote controlling a rc paramotor over wifi or bluetooth but as you found out too, constantly getting your code interrupted by an OS can be a real pain :D
The cube looks awesome. What's the intro music?
Blue Ribbons by TrackTribe
this is the standard arduino setup...charlieplexed... ive still got my 4x4 cube sitting here i built in 2014...(i would have made more but..didnt have the leds on hand)
you should really be using transistors on each row to power the leds otherwise you can burn out the mcu's gpio pin circuitry...
...you almost have a nice grid there to be able to make letters, numbers and symbols on the faces....
Indeed a weird way to make an led cube. You sure are original by making a 5 high instead of a 4 high cube, the 4 high makes for very elegant charlieplex wireing. The teensy 4 is way to powerful and expensive for this. A couple of transistors/mosfets and multiplexing combined with chalieplexing on the esp32 to reduce pins would have made more sense maybe?
I don't think I considered using a multiplexer. I've never used one before. Would you be able to set the outputs to high, low, and high impedance? Yeah the Teensy 4.0 has more power than needed, but it had enough pins and was only a couple dollars more than the only other board I knew of at the time that had enough pins-- the Arduino Mega.
It does bother me a bit to use a microcontroller that has more power than is needed for the task. It's one thing that annoys me about the raspberry pi pico. The pico is so cheap that from a money perspective, it's the ideal choice for many projects. But many projects wouldn't take full use of its power. It hurts my soul to subject such a powerful processor to a lifetime of a simple task.
rotate the cube in the results or at least pan back and forth
Oooh I like that. I could've had the cube on a little rotating display table. Thanks for the suggestion
You really put your teeth in this project. Nice result!
Nice video, thank you :)
You save a lot of pins, but you can only light up a single LED at a time rather than an entire row, reducing brightness significantly. Additionally, it makes the wiring and code more complicated, and unintuitive. Generally, I don't think the tradeoff is worth it, when both microcontrollers with a higher pin count and shift registers are cheaply available. Soldering a LED matrix is already annoying enough with conventional multiplexing. An Arduino Mega, for example, has more than enough pins for this purpose, and the clones are cheap.
Thought the same, its unneccessary complex design bringing unneccesary drawbacks. Just shift reisters for the colums and you can live with using 8 pins for a 5x5x5 matrix
@@flipschwipp6572 It is just a proverbial "thought experiment", the world gets pretty boring when everyone always converges on what, at the time, is optimal. No different than the guy who calculates pi with relays.
That's Frickin Awesome!😅
nice job david keep it up
Dude your head bobbles like Ron Desantis'
I wonder how one could make a 50x50 led cube :o
Very cool
frickin cool!
❤
th-cam.com/video/aBqBwDwHwUc/w-d-xo.html mouse? would the Pi Zero W have been able to do the job if not running a GUI?
I tried running the code on the full GUI OS but headless, and it was still flickering. Would a headless, GUI OS be as fast as a command line only OS?
Nice!
if you now put it inside a milky glass case. Imma subscribe
I did consider making a clear, acrylic case for it. I didn't think of like a frosted case. That could definitely look cool.
An LED Cube
You're right. Thanks! I didn't know that.
very cute :D
Nice project, but where was the complex part?
Turning the leds on by put them into a matrix is the most simplest way I know 😅
Why not using a adressable leds and set the color via spi dma which can run in the background of the mcu? Sounds way more complicated than a led matrix . And you can do other stuff with the mcu 🙂
So, it was easy for you at the first time? Or for anyone who is starting out with this?
I see your comment more as loathing than kind and helpful.
It may sound more complicated, but if you do something like that, you’re probably going to use libraries for the software, right? This in theory can be done without all of that. Also, using ws2812b only requires one wire going through all leds, so the wiring is a lot more simple
@@fritzlb that is the complex part, not using existing Libaries some one already did. You have to read the datasheets, set the registers right.
Especially if you have to read the reference datasheet, the device datasheet and multiple application notes to get all informations you need.
Only setting the registers isn't that hard or complex, also there are enough tutorials online for common architectures
Completely bitbanging the ptotocol in asm might be a challenge tho
adhd cube.stop moving you are making me sick man
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