Draw me to the moon…

…Led me sweep among the stars

 

So, I have a long therm project that will require a display with some particular needs.

I want it to work with 3V3, retro-looking and curved.

Yup, nothing off the shelf is going to work for me (flexy o-led displays with a big aspect ratio are not going to be a thing in time, and they don’t exactly look the way I want the thing to look anyways.

We could say I want to inspire the display in these:

The gorgeous HDSP-2000’s wich are nigh impossible to obtain nowadays at good pricings (and besides, they are small for my application). But the amber dot matrix look is just too gorgeous to let it pass, so I started drawing my concept:

8×8 groups of leds, using a SN74LVC244 line driver as row selector, and 74HC595’s shift registers to select the columns using a clock signal (and a start pulse). The thing is, when I started this, I was not sure I could program a microcontroller well enough to actually use such a display (for some people it would be awalk in the park, but to me, programming is always a chore I don’t particularly like to do). Of course, since this post doesn’t have a doomed kind of tittle, and I’m actually writing this post, is fairly evident I succeeded.

Oh, sorry, spoiler alert. XD

 

 

Anyways, so I just put myself to Altium the shit out of this thing, one schematic at a time:

Then PCB it:


Damn altium. XD

For a moment, I was also afraid I would have to chase every individual led, however Altium was kind enough to group them in couples of 8 leds:

At first I just put them horizontally, altough I knew I was going to rearrange them to be as compact as possible (1206 led footprint):


90º rotation and compaction afterwards:

The other componentry:

It’s not like it’s a particularly difficult board, but I spent an insane amount of time compacting it for a 2 layer board. (remember, this is a prototype to test my programming skills (and secondarily. that the circuit worked).

8 row input lines, a clock input and traveling pulse input.

And, since I was at it…made it BLACK:


Nope, there was no way of avoiding those three jumpers without heavy board remodelling, and I was tired of it already. Two weeks later:

First, a bit of testing:

Once I was satisfied I assembled the rest, and lo and behold!

Consumption is moderate at 40-ishmA, as per design.

However, not everything was perfect in the land of the led. Previous tests where only lighting one led at a time sequentially, and that is innefficient both because I designed a parallel load, AND because reduced overall light intensity per led. Given that I was already working at very low levels (5/8mA per led) reducing it even more was not going to help with visibility. When I tried to start doing more, this happened:

 

That line was supposed to be one led thick, but somehow, the line was doubling horizontally.
Hummmm…
Quick check with the scope:


LMAOOOOOOOOO, no wonder the leds where doubling, I had made the software in such a way that it put the (blue) led activation, in between column pulses. XDDDD
Some softwareing later:


Nice and cozy!
Beautiful pulse-within-pulse (blue led activation, yellow, column selection).

After some more fiddling with the STM32F103:

BAHAHAHAHAH…Had to be done, sorry-not-sorry. XD

Some more poking:

The software side, in the next post, folks!

See ya!

Let there be light.

I can’t see shit…

 – Old german proverb

Well, new year, new challenges:

  • Starting fresh, no job, no big workshop and too much free time. I almost got a new character sheet, but the DM of this game didn’t allow it. XD

So, what did I do first? get equipment!
The microchip endeavor is not going to get done it by itself, and I decided that is my main goal for 2020.

A metallographic microscope for those beautiful die shots:

More about it later, as it deserves a post of it’s own.

A new hot plate:It was very cheap, and that way I don’t have to deal with my own homemade.

An ultrasonic screwdriver dental tool to try to build my own wirebonder. This one is going to be fun.

A bubble bath ultrasonic cleaner:

And a few other random bits and bobs for this.

Later I’ll do a post on each one, but for now, ya’ll know what is going on.

Oh, btw, I made a Patreon!

Who The Fuck Even Reads This.

Some background music, because I can:

So, what have I been up to?

Not much, really.

tl:dr
Got a good job, learned to survive in Arduino IDE on STM32, Opened a Discord chatroom about Semiconductors and bought a workshop bigger than my old home.

—— Work ——

So I got into a research and developement position on a trucking company of sorts. At first I was supposed to just repair messed up things from the monkeys they have as employees. However it quickly became a position where I have to basically supervise manual mechanical fabrication AND develop control circuitry and whatnot to drive it.

I can’t really show you what I’m doing because altough I haven’t actually signed an NDA, it would just tell the world what my boss wants to do, so better not to blow the whistle, right?

 —— Coding ——

Funnily enough, just before I got called from the job I do now, I had decided I wanted to give a try at coding again. However, I felt that the PIC16F873 I was using, was long past it’s prime time and better coding IDE’s and microcontrollers should be avaliable.

After inquiring on twitter, it was clear that STM32 was the new way to go. However, as my coding has always sucked, I asked if Arduino IDE (wich I had in mind it was some sort of block coding like LEGO mindstorms) and everyone told me it was a good approach with my limitations. I could always jump to something else more complex if I outgrew that.

So I am happy to say I do defend myself quite well on Arduino IDE. It makes for certain things to be soooooooooo damn easy (I’m looking at you, I2C! ¬¬ ) I feel very empowered. With the knowledge I carried from PIC and Microchip IDE, I found very easy to do the things that where just so damn complex before. Now I can reach serial comunication, wireless comunication, and quickly program things I only dreamt before (I’m still not a genius coder, do not expect that).

—— Discord ——

So, after Twitter showed it’s limitations as chatroom, I was shown The Discworld Discord. I quickly grew fond of it, but my semiconductors interest was limited by the control others had of their chats, and with that, I decided to have my own playground to share that:
https://discord.gg/a7kkUUr

You are welcome to join, but remember, it’s extremely semiconductor specific. There are other Discords for more general chat. (not that that is forbidden, just that the topic is very particular)

—— Workshop ——

001 (2)

TOP: From the middle to the entrance.

BOTTOM: From the center to the back:

002 (2)

Long workshop is long.
Measuring about 25m in lenght (yes, that’s fucking long) by about 3m wide. (with width variations along the rigth lenght, but one flat-ish wall to the left. That gives 78sqm of my own personal space, but the best part is that it has installed a mezzanine of about 40sqm more.

AND I always have wanted a workshop with a mezzanine.

I do have literally TONS of work to do. The whole floor has to be removed in it’s entirety, because it’s crooked and just bad quality. One non-main wall has to be toroughly repaired (brought back to vertical and clamped) and a few repairs here and there, wich will make a lenghty process before I can populate the space with tools.

BUT…

It’s my own real workshop. Bigger than many makerspaces, and it only has to hold a single person, wich is a plus. XD

And that’s pretty much it. The workshop renovation will be thoroughly documented, so expect updates on that from time to time.

Nixie out!

Helm-ets Deep.

So, one day I thought I felt that my helmet had become noisier. Weird, because I have a deflector on my windsheld AND I’m quite short. When I stopped to refuel I realized that the butt bluetooth plug had fallen off:

I thought that replacements might be avaliable, but having a 3D printer and skills, it was just easier to take some measurements and make a new one.

That turned into a downward spiral of creativity I hadn’t planned at all… :033:

The thing is, I have an internal bluetooth (Just Speak) because I hate the bulkyness of the external ones. The only drawback is that for charging I have to fully open the helmet and remove a foam flap to access the microUSB port, wich is slightly annoying.

As you can guess, while working on the plug I wondered…”Can I add a microUSB port to the plug and connect it to the inside of the helmet?”
Well…it seems I can.

So I proceeded to design a flexible PCB to connect it to the inside.

 

 

A few weeks later:

This was my first flexy pcb, so I messed slightly. Especially by not optimizing the connector position (vertical instead of horizontal) so the pcb was more expensive that needed. It also looked a bit weird, with a forced bend and such.

In any case, the thing worked, but then I realized that I would not be able to check the status light/charging, so a wild idea came to my mind…What if I put some fiber optics in there?

So I modified the design to include a 1mm PMMA fiber in there. Interestingly enough, I already had to add a spacer in the inside connector anyways, because the male part was 2mm longer than the socket.

And the spacer:

And also, redesigned the pcb:

HOWEVER…

Meanwhile I waited for the pieces, I realized that the endcap didn’t had any form of retention, and altough that wasn’t a problem per se, I knew it would be lost at some point. So…

Yeah this had to be done. And with that, when all the pieces arrived:

Fucken awesome!

Open:

Closed:

Damn it looks cool. Also, the insides are prety clean now:

Yay!

Btw…I opened a Tindie shop, and this is for sale (this is only for CABERG DUKE SMART helmet  + CABERG JustSpeak bluetooth:

https://www.tindie.com/products/ElectronicMercenary/caberg-bluetooth-helmet-exterior-charging-port/

 

 

I ATENT’T DED!

Hello!

Yup, I’m still here, just got lost into sideprojects and jobfinding. Long and amusing posts await.
Teaser…

Semiconductor building will resume soon too. Pieces and kit tools have been gathered and should be arriving at some point by mail.

Vidicon tubes have been gathered to start electron-beam tests:

A curve tracer kit has been bought, because I’m a lazy bastard and I didn’t want to botch one in the workshop. :P

More news soon!

DONEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!!

FUCKING DONE…

The Project is finished! A sort-of-proof has been made:

(Diode-ish behaviour in a home doped silicon shard)

The documentation is done. Two books have been written. (well, more like one book and a phamphlet):

Semiconductors @ Home – Compendium!

(a knowledge gathering on all the machines and accesories built for the project)

And

Semiconductors @ Home – Cookbook!

(a step by step guide to use said machines, or similar, to make the semiconductors. A work in progress, updated often.

A video resume for the project has also been made:

I will be attending the Hackaday Superconference in November 2-5, and will be at the Poster sessions (think of a grown-up science fair) on Friday 2nd, in some obscure corner I pressume.

I will sit beside this poster and bore people to death about all the tooling.

And that’s it for now. Once I come back from the Superconference, posts should resume as “normal”.
See ya!

The wafer in the PMMA mask.

So, while waiting for the turbopump to arrive, my mind was left meandering around, and thinking about the PMMA masking, and the difficulty to obtain very low molecular weight masking liquid…

And I thought…If Silicon is sort of transparent to 10600nm laser light…but PMMA is not…can’t I just use laser etching to patern low resolution features on my test wafers?

With that thought, I prepared a test vector file with lines separated 100µm – 200µm – 300µm – etc… for the laser cutter:

Then proceeded to engrave some acrylic I had around, and McGyvered the shitty microscope we had at home:

That is nice!

That looks very consistent to me! Also, linewidth seems pretty constant (no micro power fluctuations in the laser supply)

For scale, a 110µm copper wire was placed in one trench:

The process idea is as follows:

First etch the PMMA with the laser, but not trying to go all the way, just to the top of the silicon wafer. Then, using PMMA solvant, you eat away some thickness from the leftover PMMA, revealing the silicon on the bottom of the trenches.
After that, an anneal step and you can etch the wafer. This should enable 100µm features, with 100µm spacing.