Marc's Public Blog - Electronics Hacking

flexible 16x32 RGBpanel

found a hat big enough that it mostly fits on it

of course, it needed a few LEDs :)

what it looked inside and it worked with a small 1S 700mAh lipo (although not long enough)

bigger battery upgrade, and BTW those batteries lie, they are only 1600mAh

testing battery draw, a bit over 0.5A which is a bit too much

So, why 3-4V lipos instead of USB battery packs with 5V that is expected by both the panels and neopixels/WS2812? Well, space is limited, USB battery packs are kind of big, and carry extra hardware to recharge that isn't needed inside the hat. There is also a side byproduct that powering both the panels and the LEDs with a lower voltage, limits their brightness and the amount of power (watts) they need, which means that a 16Wh lipo inside a USB battery pack stepped up to 5V, makes everyting brighter, but only lasts about half as long as powering directly from the lipo at lower voltage.

bigger 4Ah 1S lipo worked for 8H at full power and LEDs worked all the way down to 2.8V!

panel worked all the way down to 3.4A before colors went wrong, 16H on a 1.6Ah battery

of course now I had to find a buy a faster 1S lipo charger with the right connectors (had to get JST adapters)

quick test that a smaller 700mAh battery would last around 5H before things got dim

After testing, I was able to confirm that both the $7 amazon controller (SP002E from https://www.amazon.com/gp/product/B09Y8SWJ77 ) and the RGBpanels, work fine with lower voltages (which is not a given since both run a microcontroller that was originally meant to be powered from 5V).
The RGBPanel controller is a bit more picky about voltage and reboots around 3.5V, while the neopixels tend to drag the battery voltage down, causing the RGBPanel to crash and reboot when a single battery runs both, so I gave it its own lipo.

Pixels still take 0.3 to 0.5A (I use a potentiometer to dial them down as the cheap controller I put has no dimming control) and the RGBPanel takes less than 0.1A, so that's nice (it actually goes all the way down to 0.05A or just 50mA) when the voltage drops.
The combined tricks should give around 18H of runtime with the 2 batteries (4Ah and 1.5Ah 1S lipos), which is enough for 17 hours of dreamstate (they are not screwing around this time, 17H !!!)

About the neopixel controller, I used a cheap $7 amazon controller that only had 3 physical buttons but sadly no dimming control, mostly because I wanted something very small, and while pixelblaze micro is also small, it doesn't have the pattern I want, and I didn't see the point of programming a pattern I already had on the other controller, so I just put a potentiometer to lower the voltage. It's obviously the wrong way to do it, but it works :)

Here is the end result:

1) Oh, I need to finish writing code to get the SAO badge holder to do something fun

2) Mmmh, why does this python global variable thing doessn't work in the function

3) Goes to re-learn python, with help from gemini and how python forks global variables by default in functions so what you write to them isn't saved at local scope (oh my, why did they do that?)

4) after more hacking, get a proper demo working:

5) publish code https://github.com/marcmerlin/2024-Supercon-8-Add-On-Badge/blob/main/README.md (actual code is here: https://github.com/marcmerlin/2024-Supercon-8-Add-On-Badge/blob/main/software/software/main.py )

6) Oh, I need to make a video demo of the SAO, but...

7) oh yeah, there was that hat on my desk I needed to add LEDs on for an upcoming party, start hacking on that

8) mmmh, the hat won't work long enough with a USB battery, start hacking on a lipo solution

9) ah, lipos work, but the front LED panels rated for 5V start failing around 3.5V, so I need to make a dual lipo solution, one for the neopixels and one for the RGB panels

10) test and measure the dual lipo solution and figure out it will last close to 12H, that's good. Ok, hat works mostly, post that https://www.instagram.com/p/DCYEl1jJd_-
11) Ah yes, the SAO video I was supposed to work on: https://www.youtube.com/watch?v=z7MSywf7js4

12) During that time, I get interesting distracting packages on my doorstep, like lovely flexible LED panels that will hopefully power my future outfit: https://rpi-rgb-led-matrix.discourse.group/t/rpi0-2w-speed-compared-to-rpi3a/913/2

13) While I'm testing them, also try some new rPi0 2w chips and microcontrollers to see if they can power my LED outfit with a smaller form factor (and yes they can): https://rpi-rgb-led-matrix.discourse.group/t/rpi0-2w-speed-compared-to-rpi3a/913 . In the interest of briefty, I'm going to skip the part that included migrating from raspbian to a new dietpi linux distro and port back all my custom changes on it :)

14) That said, I had a long-ish discussion and planning with the electrodragon folks in China on how to make a new 3 channel daughter board that is much smaller and would decrease the over footprint of all new picture frames like the one I built, and of course my LED outfit.

15) but wait, now I also find out there is a new beaglebone solution that does 6 channels output instead of 3? Ok, make a post about it: https://rpi-rgb-led-matrix.discourse.group/t/interesting-6-port-board-beaglebone-pocketcroller-v2/918/2

16) and file a couple of RFE bugs to look into it: https://github.com/hzeller/rpi-rgb-led-matrix/issues/1733 + https://github.com/FalconChristmas/fpp/issues/2054

17) Oh, I just found this old video on my laptop, why did I never post it? Ok, fix that: https://marc.merlins.org/perso/linux/post_2021-01-23_Linux_conf_au-2021-LED-Talk.html

18) Mmmh, so when I quickly posted those pictures from Neil deGrasse Tyson who just gave a talk, I got a reminder it was annoying for my blog system not to be able to link to videos directly without having to upload them to youtube.

19) Ok, learn about html5 video tag, hack my blog system to support videos, and push a new blog with my first video tag: https://marc.merlins.org/perso/outings/post_2024-11-14_Neil-deGrasse-Tyson-back-at-San-Jose-Center-for-Performing-Arts_-An-Astrophysicist-Goes-To-The-Movies_-the-Sequel.html

20) ok, but why did I have to rescue my video from my phone because the H265 recompressed version did not work in the blog? Ah, because of royalties on H265 being too high, most browsers refuse to add support for it: http://marc.merlins.org/perso/linux/post_2024-11-17_Vidrename-Script_-Clean-up-Normalize-Video-Filenames-and-Add-Codec-And-Container-Format-With-Mplayer.html

21) Ok, sure, but now I need to upgrade my vidcomp script to support VP9 and AV1: http://marc.merlins.org/perso/linux/post_2024-11-17_Vidcomp-Script_-recompress-videos-on-linux-with-mencoder-or-ffmpeg-to-div3_-div4_-div5_-xvid_-mpeg4_-h264_-h265_-VP9_-and-AV1.html

22) then I find an Email from a chinese engineer who is willing to talk to me about making better LED shoes. That's exciting, let me reply to him first

23) ok, now I can recompress my videos to VP9, which I benchmarked to somehow be faster to compress and still smaller file size than AV1 (not supposed to be the case, but that's what I'm getting). On the plus side, VP9 works with more browsers than AV1.

24) what as I doing again? (now days have passed). Oh yes, I was supposed to write a blog on hackaday supercon: http://marc.merlins.org/perso/electronics/post_2024-11-01_Pasadena-Hackaday-Supercon-2024.html

25) of course the ridiculous amount of time spent to allow these 2 videos in that post, is a bit hard to justify, but it's really solving a problem I've had for over 10 years, and never got to the top of the pile, because, well, you see what happens when I try to put something on top of the pile :)

26) and I was good, I didn't even play with the micropython rpi micro I received in the mail this week, or the electromage pixelblaze and I/O board, or more LED panels that somehow showed up at my doorstep :)

27) mmmh, and there are all those webcams I ordered and need to configure, but now it's clear I'm going to have to re-install my camera controller, shinobi, from scratch, and that's yet another rabithole...

28) in the meantime I have to finish my LED hat, and design my new shirt and pants for Dreamstate in 4 days... Wish me luck :)

It was very cool that I got to wear my LCA SAO badges for the first time:

This post, because of its 2 video inserts, a new addition to my blogging software, was also an interesting exercise in non linear time and tasks, more on this page: Getting Things Done in an ADHD World

Day 1, Friday

Thanks to Anthony for letting me know about it, and I was able to attend. Went there early on friday for the pre-conf to work on the badges:

the conference badge was this 6 port micropython rPi micro with a couple of SAOs.

they nicely provided food all 3 days

essential geek survival food :)

They gave us a quick primer on how the badge worked, although it would have been better on a webpage with links and info for total beginners who had never used micropython and thorny or knew what thorny was (that included me):

I'm glad I took pictures of these slides, they only made sense many hours later. They should have been online

finding fellow LED geeks :)

learning blinkies for beginners, scan this

While I was there, I 9ound out they had a wonderful 4 bit computer some years back. I actually really regret not having been there that year, programming that in hand crafted assembly would have been epic:

someone hacked a basic I2C on it

people now hard at work

I used the opportunity to bring previous LCA toys and show them off (and fix a few)

People came with plenty of SAOs:

some came more ready than me :)

SAO extenders, cool!

SOA badge holder bag, sweet!

I found Tom Verbeure, the person who had been hacking on RGB Panels with open source FPGAs (colorlight). Cool project for sure. See: https://github.com/q3k/chubby75?tab=readme-ov-file#colorlight-5a-75b and https://github.com/lucysrausch/colorlight-led-cube/tree/master

Also, finally got to meet Henner Zeller, the rpi-rgb-panels author I've been working online with for years:

epic watch!

Also got to meet Daryll Strauss from precision insight, later acquired by VA Linux some 25+ years ago:

People still hacking at night:

I was lit up enough not to get lost :)

Day 2-3, Saturday & Sunday

went to attend a few talks

hacking radio sound and B&W video from a chip, super cool!

learned about an online microcontroller emulator, wokwi, very nice

I got to see a pick and place machine, nice to see them work:

this is what the machine was 'printing'

I tried the SMD challenge, that was hard as hell:

we got old and fat irons, making things harder :)

I couldn't get the last 2 LEDs working, they were so stupidly small

I had someone help me fix mine :)

and they all worked, thank you to the master solderer!

added the result on my badge :)

Random fun shots :)

people hard at work

During the weekend, the SAO wall got populated:

Original from Burning Man

more and more

and more :)

Saturday evening party had a nice real time AI image generator:

some were far out :)

The conf ended with a presentation of best SAOs:

This guy won the contest of biggest SAO, he had a printer working off USB, run by his SAO

Sunday ended with a party at a bar, thankfully I had my battery soldering iron :)

This was loads of fun, and I definitely learned some good stuff. Sad I didn't go earlier but glad I went this year. Thanks bunch to all the organizers and attendeers who contributed!

More pictures: https://photos.app.goo.gl/2hYRaaB5dF5mvv4N8

In 2021 I got my first SAO Conference Badge from Linux.conf.au (clickme for more) That LCA board had 4 SAO ports and came with 2 little cute penguins that I hacked a bit:

one of them was then in charge of running a neopixel necklace

I got a few spare SAOs to attach to my heavily hacked LCA badge :)

Anyway, back to Pasadena Hackaday Supercon 2024, they gave us a 6 SAO badge also running a micropython chip:

attendees nicely donated a few extra SAOs to me, which I wrote code for

even got an SAO extender :)

I had to solder it from parts at the after party in the pub

Back to the conf SAO and code I wrote, here is the result:

Micropython Code:

Main repo:

This was loads of fun, thanks to the organizers!