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Project Patchouli: Open-source electromagnetic drawing tablet hardware

461 points| ffin | 1 month ago |patchouli.readthedocs.io

49 comments

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hipaa_eng|1 month ago

As a software engineer, seeing hardware projects like this makes me want to go back to school and pick up a few electrical engineering courses. The hardware space just seems to unlock so much (honestly blown away with the LCD retrofit at the end of the video: https://www.youtube.com/watch?v=igVscvWAR1s )

I've played with simple electronics on the arduino and raspberry pi platforms but this is a whole new level. Anyone gone down this path? Something you would recommend?

Aromasin|1 month ago

Honestly, just pick up the Art of Electronics - Horowitz and Hill. Spend some time working through that book. By the end of it, you'll have a better grasp of electronics than 90% of the engineers I've worked with, all who are EE bachelors/majors. It's a 3 month job at most, less if you do a dedicated hour a night. Then pick up some breadboard and parts, and build to your hearts content.

Making a working circuit is honestly very easy once you know the basics. Look inside a Made in China knockoff appliance, and you'll see that most things can be made from a couple of conponents and a microcontroller. Pull apart an old TV remote or bluetooth device, and look up the part numbers and what they do. There's not much to it. You have to remember that most of the stuff getting designed and built in South East Asia is done by people with zero qualifications. Electronics being "the thing that smart university people do" in the West is mostly a mental block, culturally constructed because people don't want their kids getting electrocuted so bombard them with constant threat of death if playing with electricity (which mostly isn't a worry anymore unless you're working with mains power).

The true discipline of Electronic Engineering is designing something that works for every eventuality and environment, with close to 100% reliability, at the very cutting edge of what is possible with the components we can afford while balancing physical and financial constraints. That's something which takes years of both academic study and industrial experience.

utopiah|1 month ago

Before you dive too deep, check what's already available and let your tinker TODAY without having to solder anything. You can still do so, even design PCB and get them mailed to you (like I did, it's fun) but honestly spend a bit of time (and money) on CrowdSupply to see the plethora of fun and useful OSHW out there. IMHO only after having considered what's beyond the usual consumer electronics it is worth learning to build, not before.

CheeseFromLidl|1 month ago

I’m going to go against the standard advice of this book or that course.

Pick up (broken) equipment and start disassembling it to figure out how they turn A into B [1]. Go down the rabbit hole of hunting down the service manual of the thing or one of its siblings. Look at how the pcbs follow the same pattern in competing design. Look at how all the yamaha, sony, medion, … amplifier/tuners are made in the same way and learn from it. Notice that one that is costlier and has those few quircks in its design. Notice how different variations of a theme achieve the same result, but died out because the tech doesn’t scale or simply proved to be suboptimal. Try to repair your broken equipment by understanding the path that the signals and power lines follow.

Rinse and repeat a few years and you’ll get a grasp on what the innards of an unknown electronic thing looks like without opening it. Then open it and be amazed that there was a different, cheaper, simpler way to turn A into B.

All along the way you’ll experience that most educational resources aren’t actually that good at explaining, or that they follow a different school of mathematical notation, or that they’re really good at explaining this detail but the rest is missing.

Design your own pcbs. Remember that - like software - hardware design is iterative. Remember that - unlike software - hardware iterations cost money.

Hope this helps.

[1] the ways to turn A into B are rather limited and it relies heavily on electromagnetism and conservation of energy.

drob518|1 month ago

Forty years ago, I was on my way to college to get a computer engineering degree. I had already been programming in 6502 assembly language and was frustrated that I didn’t understand the hardware side of things as much as I understood the software side of things. Best decision I made. It allowed me to view computation as something more abstract. The barrier between hardware and software processing is artificial and can be moved one way or the other. What is CPU microcode, for instance, hardware or software? It’s really low level software that is typically burned into a ROM but is also sometimes downloaded. Even if you decide to stay with software as your primary day to day job, you’ll be comfortable talking to engineers on the other side of the line and that will help inform your understanding of what’s possible, how much it will cost to design and ship it, how long it will take, and how it will perform.

estimator7292|1 month ago

I found that programming concepts map really well to digital electronics. The objects in your object oriented language are real objects with their own internal physical state. A large fraction of what embedded engineers do is just APIs and protocols.

Controversial opinion but you do not need to learn electronics to have a good time. One can have plenty of fun simply writing software and plugging prebuilt modules together on a breadboard. Ohm and Maxwell need not apply.

JuniperMesos|1 month ago

https://en.touhouwiki.net/wiki/Patchouli_Knowledge

And then yeah he's playing a Touhou rearrangement in the project intro video. "Original: ZUN".

I wholeheartedly support weebs who create useful open-source electronics and share them with the world.

packetlost|1 month ago

I'm always happy when I see Touhou mentioned on HN. It's reasonably popular with a certain subset of hacker types that grew up in in the 2000s

amelius|1 month ago

Isn't this technique encumbered by patents? Or have they expired?

Anyway I'd be interested in the implementation of a 3D mouse also.

jsheard|1 month ago

Wacoms key patents did expire which is why there's such strong competition in the tablet space now, and why prices have fallen through the floor.

I wonder why Apple still uses active pens on the iPad when passive EMR has become such a commodity. Maybe it's just rent-seeking, a passive pen would probably be much easier to clone without paying Apples MFi fees.

abdullahkhalids|1 month ago

Some of Wacom's tablets can be used with both the pen or with your finger (acting like a touchpad).

Anyone have any idea whether the touchpad part could be made open-source? Or even some closed sourced off-the-shelf solution that could be integrated with the above?

EDIT: There is a Canadian company that has recently released an open source trackpad called the Ploopy Trackpad [1].

[1] https://github.com/ploopyco/trackpad https://ploopy.co/trackpad/

coffeeaddict1|1 month ago

As an aside, anyone here uses drawing tablets for work? I got a cheap Wacom tablets and found it super useful, for sketching ideas or understanding something before starting to implement new code.

adrian_b|1 month ago

For the last few years, I have been using small Wacom Intuos S tablets as a replacement for mice, trackballs or touchpads.

I configure the tablets in the "Relative" mode, in which they behave exactly like a mouse, unlike in their default "Absolute" mode. I configure left click to be done by touching the tablet with the stylus and the 2 buttons that are on the stylus to generate right click and double left click.

The advantage over a mouse or trackball is the much more comfortable position of the hand and also the much higher speed and accuracy of positioning. Moving the pointer to any location on the screen is instantaneous and without any effort, due the lightness of the stylus and to the lack of contact with the tablet.

Because the stylus is extremely light, I can touch type on the keyboard while still keeping the stylus between my fingers. This allows faster transitions between keyboard and graphic pointer than with a standard mouse (because the time needed to grip the mouse is eliminated). Only when I type longer texts, I drop the stylus on the tablet.

The tablet is no bigger than a traditional mouse pad, so it does not need a bigger space on the desk.

After switching to use exclusively a graphic tablet, I would never want to use again a mouse, trackball, trackpoint or touchpad. I only regret that I have never thought earlier to try this.

Besides being a better mouse than a mouse, a tablet obviously allows to do things for which a mouse is inappropriate, e.g. drawing or handwriting (e.g. for signing a document).

I should mention that I have always used the Wacom tablets with Linux. I have never tried them on Windows, so I do not know if there they work as well.

Bapannarama|1 month ago

Possibly not the use-case you're thinking of, but I've been using a Wacom Intuos tablet as a mouse replacement for a few years now on MacOS and on Linux. I use it in pen mode (where the area of the tablet maps to the screen) - you can also configure it in mouse mode (like a touchpad, where the movement is relative to where the cursor is on the screen) which should work better with multi-display setups, though it's not to my preference. I have my pen/stylus setup so that tapping it onto the tablet acts as a left/primary click, the larger button on the pen is right click, and holding the smaller button and dragging on the tablet is scroll/pan).

MacOS is well-supported once the drivers are installed, though sometimes the driver doesn't seem to pick up tablet (either after the laptop or tablet goes to sleep). Restarting the driver fixes this, though this bug seems to have been fixed in the latest driver release. Linux works out of the box (at least on KDE/Arch), though sadly customization support on Wayland isn't quite there yet compared with what you could do on X11 (with the xsetwacom utility). For drawing support though it should work perfectly but as far as I know you can't the the button functionality, which is a bummer when using it as a pointing device.

The main benefit for me is that it feels much more ergonomic compared with a regular mouse or even a vertical mouse or trackball and I don't get anywhere near as much wrist or shoulder pain - especially in the cold temps in the middle of winter where I am. There is a bit of an adjustment period and I find for interacting with small UI elements such as buttons it can be a bit tricky, but for me the benefits outweigh the downsides. The only other downside I can think of is that when using the tablet over bluetooth (wired is also an option and tracks a little more smoothly) the battery only lasts 1½ days compared with the weeks/months a wireless mouse would go for.

egypturnash|1 month ago

I'm an artist and haven't used a mouse since somewhere in the 00's when I developed some RSI in my index finger while working in the Flash animation mines.

Annoyances: games that require you to push the cursor against the edge of the screen to move the view, app/website developers who force tiny scrollbars that constantly hide themselves despite me setting the OS to never hide scrollbars, having to restart the tablet drivers most of the time when I move between having the laptop docked with the big screen and big tablet on the desk, and taking it out to a cafe or the park and using the smaller tablet that lives in my laptop bag.

WillAdams|1 month ago

Yes.

I've dreamed of using a stylus and tablet since reading _The Mote in God's Eye_ when I was young, and have preferred to use them since using a "Koalapad" attached to a Commodore 64 in the school computer lab when I was young.

The NCR-3125 I had was donated to The Smithsonian by the guy I sold it to, along w/ a lot of other materials on pen computing --- PenPoint was my favourite OS alongside NeXTstep, and the high-watermark of my computing experience was using the NCR running PenPoint as a portable, then cabling it up to my NeXT Cube to transfer data --- had a Wacom ArtZ attached to the Cube, so still had a stylus, just it wasn't a screen.

Futurewave Smartsketch is still my favourite drawing program, and I was very glad that its drawing system made its way through Flash and into Freehand/MX (which I still use by preference and despair of replacing). If you have a graphics tablet, be sure to try out:

https://www.wickeditor.com/#/

Hopefully the folks making Graphite will figure out that it's a core functionality for a drawing program to work w/ a graphics tablet --- haven't been able to do anything when I've tried.

I sketch (either on a Samsung Galaxy Note 10+ or Kindle Scribe or Wacom One or Samsung Galaxy Book 3 Pro 360), take notes (mostly on the Scribe), do block-programming (Wacom One or Book 3), or draw (on the Book 3).

hypertexthero|1 month ago

Yes, but Wacom recently discontinued macOS driver support for older versions of the Intuos, and I had to downgrade to an older driver to make it work.

When it doesn’t anymore I’ll need to get something else, probably an iPad so I can also use it as a 2nd screen.

Aherontas|1 month ago

I am doing exactly the same, also writing down some raw ideas I have in it to not forget them.

quijoteuniv|1 month ago

Beautiful! Added to list of projects! Retrofit into screen of old 27» 2009 imac that is run by a raspberry and drived by a screen driver.

TechniKris|1 month ago

This seems very similar to another open-source tablet effort, which went a step further and designed a Hall effect sensor-based tablet: https://github.com/pompyboard/pompyboard

The creator of it has showcased the prototype at an osu!* streamer's channel (since low-latency absolute positioning devices are highly desired for playing osu!): https://www.youtube.com/watch?v=v1afJ7OpacU

* that is osu! (sic) rhythm game, not to be confused with OSU universities

Karliss|1 month ago

Has it actually reached properly functional state?

The showcase video didn't look very convincing and neither website nor the discord channel contained a lot more information. Although I didn't dig through discord history too carefully.

It's one thing to hook up 200 hall effect sensors to a MCU, and read few of them or send data over HID at 8000Hz. It's different thing to read all 200 at 8000Hz and figure out the position with reasonable resolution and accuracy.

Can it also detect the exact moment pen touches tablet or additional button clicks? Or does it require taping keyboard with other hand? Which is probably fine for OSU, but less so for drawing.

random_duck|1 month ago

I love the cute diagrams in the `Scan Rate Optimization` section.

ZiiS|1 month ago

Very well written reverse engineering documents.

random_duck|1 month ago

This is such a great project! I want one!

cbeach|1 month ago

Someone donate to this guy so he can upgrade his 20 y/o Thinkpad!

Guestmodinfo|1 month ago

Awesome

Guestmodinfo|1 month ago

Why negative points. Can I not say I'm happy he or she made this project. It's not for the internet. It's for the content poster only I wrote that I liked it. At that time I was the only poster. I didn't write first! I wrote awesome. Because I liked it. Don't assume that everything is for you the reader to read and not the poster to read