A Pixel Purse LED Cube Controlled by a Cisco 3G Modem | Hacker News Reader

A Pixel Purse LED Cube Controlled by a Cisco 3G Modem

tomverbeure.github.io

118 pointspicture18 comments

Cool writeup! Also, this is painfully recognizable...:

> Even with the most important components in hand, I didn’t actually started building anything: my attention had shifted to other projects.

First they recruit 5 co-workers to order 12 panels given Amazon's 2 panels-per-customer limit... only to have attention wander for a few months, haha.

3 months between purchasing the goods and starting to work on it is really not bad and definitely below average compared to some of the other stuff on my shelves.

One of the best parts of a hobby is the freedom to not do something when you don’t feel like it.

> One of the best parts of a hobby is the freedom to not do something when you don’t feel like it.

This is a much more compassionate view to take, you're absolutely right. I shouldn't be so hard on myself for not immediately following through, its a hobby after all..!

Indeed. I’ve got a mill in the basement for 5 years waiting on a CNC conversion. (I’ve used it manually in the meantime, but that’s the most physically obvious long-delayed hobby project.)

Cool project! Quick question: Is this https://imgur.com/a/V3iRPKf an artifact of ghosting effect or refresh rate? How many FPS is the video running at?

IIRC (I did this in 2018-19), the image updates at ~58 frames per second.

There were numerous difficulties in making video of these. The LEDs' duty cycles are actually very short. HUB75 lights at most one row in 32 at any given instant.

I shot all my video on an iPhone. The iPhone does who-knows-what processing to its video. It apparently does not scan top-to-bottom, but in bands, and it dynamically changes exposure times based on unknown heuristics.

Here are some fails for your amusement. https://imgur.com/a/csSytw2

Recent gateware changes have increased the LED refresh rate to ~280 Hz, and that has changed and generally reduced video artifacts, but has not eliminated them.

I can't tell you exactly what happened on the still you posted.

I think it’s an artifact of desynchronized refresh rates between camera and cube.

This is a video of Kbob’s cube, not mine, BTW.

I've seen the same effect on actual LED screens in-front of me running synchronous content. So, a camera was not involved. This is why I ask becuase I've always wondered what might be causing this.

In that case, it’s probably due to a lack of double buffering.

Please animate a self-solving Rubik's Cube.

Not what you're requesting, but:

Floating Self-Solving Rubik's Cube

https://www.youtube.com/watch?v=2vG-YtRmBSw

That’s the kind of great idea that may motivate me enough to spend some more time on this!

Yeah, that was one of the first projects ever.

I still have my 2 mc^2 purses. Well just the parts. I also convinced my coworkers to order additional purses for a future project. They liked them so much they decided to keep them. And they were $8 so it’s not like I couldn’t order more. Than the price shot up to $40-$50 the following week!

Yeah the real hack was getting those purses at $8

You can get the same panels off AliExpress for around that price.

What is the true value of these panels? Strange how they are on sale for 90% off for a day.

The purses were on sale for on and off between August and November 2019. On AliExpress, they’ve always been around $15.

This was probably a sale to reduce inventory? I’ve been told that this kid’s show has been discontinued, so I wonder who’s still be buying this merchandise…

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