Behind the Scenes of Issue 76

Duplex matrix feedback, round-robin matrix research. New donors, April stats, upcoming KBD.NEWS scholarship(?).

Hey y'all,

Welcome back for another edition of Keyboard Builders' Digest (this time Issue #76), a weekly roundup of this DIY keyboard focused newsletter and blog from Tamas Dovenyi – that's me. If you are new to this, you can read how this started out and what this is all about nowadays. If you like what you see, you can subscribe to the newsletter (free) and donate some bucks to keep this otherwise free and ad-free project alive.

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Duplex matrix feedback

I got a lot of feedback on the duplex matrix write-up on various platforms. Reddit, Keebtalk, Deskthority, both public and PMs.

Even Ikeji contacted me, who btw has probably the best content on this topic (in Japanese) and whose posts I used as a reference for that "Japanese" duplex matrix write-up – or double matrix how he calls it.

This time he assisted me providing another lot of links pointing to his documentation of weird matrices.

Understandably, most people asked about ghosting last time, and knowledgeable users pointed out the voltage drop part of this method.

I tried to address this issue in more details in this week's Round-robin matrix write-up.

Truchet tile generator

I've wasted way too much time on the amazing Truchet patterns and cellular automata this week. :D

I'm more of a server-side guy so created everything in PHP but will try to rewrite my code into JavaScript for you.

New supporters

Thanks to Paul Kischlat who supported this project last week.

And as you can probably tell by looking at the sidebar, PCBWay donated a visible amount of money too, which put them right at the first place of the donor list.

I can't really recall how this cooperation started or by whom it was initiated at all because I'm in a constant (sometimes chaotic) correspondence with various vendors and manufacturers to secure some discount codes for you.

And sometimes, they simply find that beside supporting you (the general reader base) they would support my project too.

So from all the PCB manufacturers I reached out to, PCBWay is the first donor who supports KBD.NEWS. Newsletter fee is covered for some time now…

And of course they offered a coupon code for you too. So when ordering from them, feel free to use the KBDNEWS code to redeem $5.

April stats

About page updated with April stats.

I totally forget to check my Cloudflare interface (and their free plan doesn't allow to access historic data) so this time I'll only be able to share the chart from April 2 to May 2 – which is May 1 in practice I guess.

To sum up, there was a (usual) 10-13% increase in all the important indices (pageloads, sessions, unique visitors).

That means about 66,000 unique visitors last month.

Actually, there was a strange phenomenon too: Historically, and quite logically, Mondays are (were?) the days with the most visits since it's the day the newsletter is sent out and when I pollute all the keyboard communities with my posts.

Usually, it's a peak on Mondays on the chart and then on the following days this value goes back to normal.

However, since two weeks, pageloads have kept registering in these peak ranges for days, and the "normal" phase began on Thursday/Friday. In addition, the all-time visitor record is a Tuesday now.

I tried to find the cause of this but it seems to be generic: it isn't caused by a single post and the source of visits is quite diverse too.

KBD.NEWS Scholarship?!

So I got a limited number of discount codes from an undisclosed company.

Not the usual 5-10% discounts you see from most vendors but more generous ones.

Apparently, they want to break into the keyboard hobby/industry/community and promote their services so I thought I'd give these discounts to readers who, in return, could write a short post about their projects.

You could make your PCB project for free or for considerably cheaper, but have to write a short evaluation of the company's service which will be published here on kbd.news at the end of the usual post on your project.

I'm not sure about how intriguing and appealing this sounds. I'm not really familiar with the difference between the production quality and prices of various manufacturers either.

Anyway, let me know if you're interested.

To apply, you'll have at least a half-baked PCB, preferably an open-source one, because the discount codes will expire after some time.

I will disclose the company and the details next week. Just wanted to let you know this opportunity to start designing your PCBs. ;)

(I got five coupons as a test with the promise of more if this cooperation will turn out well.)

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That's all for today folks.

Feel free to comment in this issue's r/mk thread, and as always: keep learning and building.

Cheers, Tamás

The btrfld

SolidusHal's btrfld is a quite unique foldable, low profile, tenting keyboard.

Pronounced "butter-fold", btrfld is the foldable, portable sibling of SolidusHal's btrfly keyboard introduced almost exactly a year ago.

This is a handwired prototype but the STLs are published.

Folding mechanism

The keyboard features a carefully crafted and pretty unique folding mechanism for better portability:

Features

• folds flat for portability
• ortho-ish layout
• 5-key dactyl-manuform-mini thumb cluster
• low-pro, flat, tented qwerty keys
• 6 extra mappable keys
• Bluetooth (optional)

GitHub repo with more photos: https://github.com/SolidHal/btrfld

Melodicade MX

The Melodicade MX is a portable 6+ octave MIDI keyboard by Michael from KOOP Instruments showcasing the Wicki-Hayden layout.

KOOP Instruments' Michael released the files of his Melodicade MX, a 6+ octave MIDI keyboard built around a Teensy 4.1 and sporting Cherry compatible keyswitches beneath the 3D-printed caps arranged according to the Wicki-Hayden layout.

I've already featured some musical keyboard projects here on kbd.news, e.g. xpercipio's XP64, the Plinky PCB-synth or mpark's Gadgetina which uses the Wicki-Hayden layout as well. (And more.)

However, the Melodicade is simply too well-documented to leave it out. And as a surprising turn of events, its final form was inspired by the mechanical keyboard of the author's son (earlier prototypes sported the bulky arcade buttons):

So when my son built a mechanical keyboard in late 2020 I purchased a couple hundred additional switches to see if cheap switches with 3D-printed keycaps could work as a viable alternative – KOOP.

To sum it up real quickly, the Wicki-Hayden layout is a brilliant idea which ensures you can play all the chords by using the same pattern, regardless of the key. This may sound not that extraordinary for guitar players but it definitely is for pianists.

Patented by Kaspar Wicki in 1896, and independently rediscovered by Brian Hayden in 1986, the W/H layout is a compact musical keyboard layout which actually makes sense. If you play any musical instrument, just spend some time thinking about how much easier this layout could make learning all the scales and chords.

As a DIY keyboard project, the Melodicade excels with its great documentation.

To tease the project, here is a quite comprehensive video demonstration – as already told, the layout was not entirely new to me so this time I was especially flattered by the transposing part and the insane "stretching" possibilities:

Project page with detailed build guide: https://www.koopinstruments.com/instrument-projects/melodicade-mx

Thingiverse repo: https://www.thingiverse.com/thing:5237193

Sparrow62

Atsushi Morimoto's Sparrow62 is a split keyboard sporting a single Pi Pico with KMK.

First things first: the latest iteration of Sparrow62 (v2.0.5) has actually 63 keys while the silk screen on the PCB reads "Sparrow64". This is an error of the legend.

Unfortunately, just like many other Japanese models, the Sparrow62 is closed-source and is distributed as a kit on booth.pm. However, I thought it's worth sharing anyway.

Designed by Atsushi Morimoto aka @74th, the Sparrow62 is a split initially inspired by the Lily58.

Features

• Driven by a single Pi Pico (and an MCP23017 IO expander).
• The layout is columnarly staggered, but the stagger is so slight I'd consider it an ortho.
• It's hotswap and can be used with MX, and Choc v1/v2 switches.
• Compatible with 60% keycap sets.
• USB Type-C

It comes with a detailed build guide, and a "height guide" suggesting setups for different keyboard heights (from 15mm to 23mm).

Toast keyboard

Toast keyboard is an open-source split design by vpz for those with index fingers shorter than ring.

Fellow redditor u/vpz published his Toast, an ergo split for people with shorter index fingers.

According to my readings, those are mostly men, but the relation of the index/ring finger lengths (2D:4D ratio) depends on the balance of different hormones during a specific stage of pregnancy.

The ratio of two digits in particular –- the palmar 2nd (index finger) and 4th (ring finger) – is supposedly affected by fetal exposure to hormones, in particular to testosterone, and other androgens; this 2D:4D ratio could therefore be considered a crude measure for prenatal androgen exposure, with lower 2D:4D ratios pointing to higher prenatal androgen exposure (source).

However, 2D:4D ratios vary greatly between different ethnic groups and this variation is far larger than the differences between sexes.

In the end, vpz designed a keyboard for Berbers, Uygurs, and Jamaicans. :)

Features

• Aggressive column stagger
• Very aggressive index finger stagger for people with index fingers shorter than ring
• 5 degree splay angle on pinky and ring columns for natural outer finger angle
• No splay on index finger column since the board is for shorter index fingers
• 11 degree angle on middle column from board edge for neutral wrist angle
• Home thumb key centered on inner index row and second thumb key on toward-the-palm motion

Additionally, the boxy design and mounting holes provide stability and give options for accessories like cases, tenting, etc.

The build above includes Elite-C controllers for USB-C connectivity, gChoc 25g switches, and MBK profile key caps.

Files

The project is open-source: https://github.com/vpzed/keyboards/tree/main/toast

Reviung_ish

Frederik's keyboard dubbed the Reviung_ish extends the distinctive Reviung layout with a number row.

In addition to the number row, fredbabe increased the number of thumb keys and adjusted the spacing too:

It’s built on top of the Reviung with a number row and choc space – fredbabe.

Preliminary GitHub repo (to be cleaned up soon):

https://github.com/fredbabe/reviung_ish

Square or round-robin matrix

Let me introduce the square or round-robin matrix (aka Charlieplexing for keyboards) – a very tricky one promising 380 keys with a single Pro Micro.

After the (Japanese) duplex matrix, let's cover another one utilizing the voltage drop across diodes to avoid ghosting: the square or round-robin matrix with the promise of 380 switches handled by a single Pro Micro.

Attention! To avoid ghosting, electronic components have to be chosen very carefully!

Apparently, if this would work flawlessly in all situations, bidirectional scan would be already part of QMK and all the other keyboard firmware I guess.

The fact that this isn't the case (except PRK) means you have to keep in mind some limitations when using this matrix.

Regardless, even if you can't avoid ghosting entirely in your project, this matrix approach is absolutely fine for e.g. macropads – when you want to minimize the number of pins used.

Caveats

Let's start right with the caveats since I got plenty of questions and suggestions after posting the previous duplex matrix write-up.

• The threshold voltage for LOW state should be reached with only two diodes this time (unlike with the duplex/double matrix where three diodes had enough cumulative voltage drop to prevent false positives).
• So you have to carefully select electronic parts.
• You may use two diodes with each key in certain scenarios (e.g. Atmega32u4 at 5V).
• Fully eliminating ghosting isn't possible with some controller vs logic level combinations (e.g. RP2040 at 2.5V).
• And you probably shouldn't use this for wireless builds either: As ZMK's petejohanson points out, these matrices may force a constant scan, which has a significant impact on battery life.

Other than that, feel free to experiment with this matrix. :D

Basic concept

In the Round-robin matrix, we place two switches between each pair of pins (in all combinations).

There are no dedicated column and row pins either, which may be confusing if you're used to basic keyboard matrices. Each pin behaves both as col and row pin at some point during the matrix scan.

Don't panic if this doesn't make much sense at this point, we are going to explain all the details.

Naming conventions

Charlieplexing? Square matrix? Round-robin matrix? Yet again, naming of this kind of matrix may be confusing.

Apparently, this is an adaptation of Charlieplexing for keyboard matrices (which itself has alternative names like tristate multiplexing, reduced pin-count LED multiplexing or complementary LED drive) – however, I've never really heard any of these expressions with regards to keyboards.

Ikejima, whose great matrix classification is actually the main source and reference for this write-up, calls this the Square matrix – simply because we can scan N-square keys with this method. (Well, almost: N*(N-1) or N2-N.)

Another name is round-robin matrix, used e.g. in the PRK wiki. The term round-robin is quite apt since two switches (with opposing diodes) are placed between each pair of pins – just like contestants meet each other in a round-robin tournament.

3-pin example

To provide a relatively easy-to-understand example, let's start with only 3 pins, putting our switches between them in every possible combination:

This doesn't even resemble a proper keyboard matrix so let's look at a 4-pin one arranged into a grid:

Ghosting issue & feasibility

Unlike the duplex matrix, where three diodes ensure false positives won't occur, the round robin matrix may require very careful planning.

With the round-robin we have only two diodes so we may easily experience ghosting:

In the example above, while holding down SW1 and SW5, SW3 is registered as pressed too.

Let's see if we can eliminate this by utilizing the voltage drop across diodes.

There are all kinds of diodes with different voltage drops: the 1N4148, probably the most generic diode in this hobby, has a forward voltage drop of around 0.7-1.0V (0.72V according to some datasheets). However, this voltage depends on multiple factors like the current, temperature, etc. Other diodes have different voltage drops, e.g. a 1N4001 is characterized by 1.1V.

In hindsight, the duplex matrix was easy: by the time the signal makes its way through 3 diodes it's low enough that the GPIO registers it as off (in most scenarios).

However, we have only two diodes here in the round-robin. Let's investigate two popular controllers with some common logic levels to figure out which one work. Firstly, let's do some math with RP2040 as w0lfwood suggested last week.

RP2040

The RP2040's digital IO voltage (IOVDD) can be configured to be 1.8V, 2.5 V, or 3.3 V (table 5.2.3.4). But things are not black or white here. HIGH is not just 3.3V but a range. Similarly, LOW is not 0V but a range too. The RP2040's GPIO pin will sense 0 reliably with a maximum voltage of 0.63 V, 0.7 V and 0.8 V, respectively.

So our goal is to bring e.g. the initial 3.3V into the V_IL range of 0-0.8V.

The question is: is there any chance to reach those low voltages with only two diodes (AND staying in the HIGH range at the same time with one diode)?

1.8V -> (1.8-0.63)/2=0.59. Looks good at first sight. We need at least 0.59V drop per diode, and we have 0.7-1V with the most common 1N4148 diode. One box checked. However, at 1.8V logic level, the lower threshold for HIGH is 1.17V and we are below that (in the undefined zone) with a single 1N4148 (1.8-0.7)…

So for this setup to work we need diodes with above 0.59 but below 0.63V drop… I'm not an electrical engineer, just a keyboard hobbyist, so don't ask me if this is possible in a reliable way.

2.5V -> (2.5-0.7)/2=0.9. This is the only clearly impossible combination in the studied cases. Two diodes with at least 0.9V drop are needed to get to LOW, but the minimum voltage to stay in the HIGH zone (1.7V) would allow only a drop of 0.8V…

3.3V -> (3.3-0.8)/2=1.25. We need a diode with a voltage drop between 1.25 and 1.3 (to stay above the 2V lower limit of HIGH at the same time). Hm.

Atmega32u4 (2.7-5.5V)

From the Atmega32u4 datasheet (29.2 table):

5V->V_IL=0.9V, V_IH=1.9V. 3.3V->V_IL=0.56V, V_IH=1.56V.

3.3V -> (3.3-0.56)/2=1.37. We need a diode with a voltage drop between 1.37 and 1.74 (to stay above the 1.56V lower limit of HIGH at the same time).

5V -> (5-0.9)/2=2.05. We need a diode with a voltage drop between 2.05 and 3.10 (to stay above the 1.9V lower limit of HIGH at the same time).

However, this is when you can try two diodes. E.g. many diodes have a nominal voltage drop of 1.1V, but Ikeji used 2x1N4148 with success.

Firmware

For the software part, e.g. in QMK without a custom matrix.c (or elfmimi's pull request), we can set the same pins in the MATRIX_ROW_PINS and MATRIX_COL_PINS arrays (but in different order to trick bootmagic – explained here), and utilize a matrix mask.

Check Ikeji's full example here.

Hey, you babbled about 380 keys…

Yeah. So with 18 pins of the Pro Micro we handled 81 (9x9) keys with the basic matrix, doubled that (162) with the Japanese duplex, and with the round-robin matrix we can increase that to 18x17=306.

However, by utilizing the two LED pins of the Pro Micro you get 20 GPIO pins or 10x10=100 keys (basic matrix), twice as much with the Japanese duplex (200), and 20x19=380 with Charlieplexing.

At this point I should probably include a nice photo of a kick-ass 380-key macropad but I'm not gonna try to build anything like this, sorry. :D

Outro

Wow, you made it to the very end! Congratulations and thanks for reading. I hope this wasn't entirely useless.

Your reward is a dad joke:

"What did the fish say when he hit the wall? Dam."

Credits & Resources

Many thanks to Ikeji for all the awesome resources and his assistance.

• (Japanese) duplex matrix or double matrix
• Petejohanson's comment on duplax vs wireless builds
• Charlieplexing
• Ikejima's keyboard matrix classification
• PRK firmware – Keyscan matrix
• Round-robin tournament
• RP2040 datasheet
• ATmega32U4 datasheet
• elfmimi's QMK pull request
• QMK setup with custom matrices by Ikejima
• QMK code example by Ikeji

Truchet tiles

Random Truchet tiles on your PCB's silk screen.

I love stumbling upon topics which lead me to a chain reaction of unexpected discoveries – and ButteredBread5255's post on his Sweep-based split was exactly this kind of submission.

I put some squiggles on the silkscreen to make it look cool – ButteredBread5255.

As it turns out, the author wanted a pattern that felt organic and that you couldn’t tell if it was random or not.

He ended up with (quote) "Truchet tiling of the Rule 30 cellular automata".

This überfancy expression paralyzed my brain for a few seconds but then I turned to Wikipedia as the perpetrator suggested.

Truchet tiles

So Truchet tiles, first described by Sébastien Truchet in 1704, are various square tiles decorated with "patterns that are not rotationally symmetric".

Still too fancy of an explanation? That means simply by rotating them you have a new tile and by arranging them on a plane, they create cool patterns.

The original Truchet tile is simply this one divided into two parts along the diagonal. Rotating this results in four different tiles/orientations:

The quarter-cirlce one on ButteredBread's PCB (below) was popularized by Cyril Stanley Smith (1987). It has only two "states" but can create spectacular patterns.

So filling an area with these tiles, oriented randomly, results in cool patters. But ButteredBread took it to the next level by applying the rules of #30 cellular automaton to make his Truchet tiles more organic.

Cellular automata

A cellular automaton is an iterative array, a set of cells (e.g. pixels or tiles) with on/off states (or orientations), their neighborhood, and a ruleset to generate the next iteration.

A new generation is created (advancing t by 1), according to some fixed rule (generally, a mathematical function) that determines the new state of each cell in terms of the current state of the cell and the states of the cells in its neighborhood.

A good example is Conway's Game of Life.

Cellular automata can work in any dimensions, but one-dimensional cellular automata are especially great because they can easily be represented visually as an image: e.g. each line is a consecutive generation of a cellular automaton (source). And Stephen Wolfram, British-American computer scientist, has researched exactly this field for decades: one-dimensional cellular automata.

The color of a cell is defined by the color of that cell and its immediate neighbors. There turn out to be a total of 256 possible sets of rules and these choices are numbered from 0 to 255.

Rule 30 cellular automaton

Many of the rules generate meh images, but even though all the rules are very simple, some of them show remarkably complex behavior.

The first in the list that does that is rule 30 – Wolfram's favorite example:

(Wikipedia page)

Others may be fascinated by it too because there are even buildings decorated with the rule 30 pattern.

How to reconstruct the pattern

Unfortunately, I wasn't able to contact ButteredBread, but here is his workflow according to the original post:

I wrote a program in JavaScript to make the pattern, imported it into Inkscape to rotate and position it, then exported it from Inkscape and imported it into Kicad – ButteredBread5255.

Well, there are plenty of Truchet tile generators out there. They won't generate the tiles according to cellular automata but spicing it up with pretty much any randomization method may result in similarly cool patterns.

I made a quick and dirty Truchet generator for myself but it has to be cleaned up before publishing.

Finally, a similar concept with a one-liner: “10 PRINT CHR$(205.5+RND(1)); : GOTO 10” – and this is arguably one of the nerdiest book titles ever.

1970s Cortron keyboard

A gorgeous Cortron keyboard with ITW magnetic valve switches made for Sperry Univac systems. Posted by catsontuesday.

So this gorgeous 1970s Cortron keyboard (assembled by Nifco Inc.) with ITW magnetic valve switches made for Sperry Univac systems was posted by catsontuesday.

Beautiful compact 55% layout with two "ISO Enter"-shaped caps. More photos of the interior on Deskthority.

This keyboard was used with the Sperry UNIVAC Universal Distributed System 2000 (UDS-2000) which was a data entry system introduced in 1978.

Here is a Univac brochure from those days with some cool photos, e.g. this one:

The basic UDS 2000 consisted of a master workstation with 32K bytes of memory, a 9-inch dot matrix display CRT with a 512-character display, a keyboard and a floppy disk drive. Optional attachments included the Univac 0786 character printer and the Univac 0781 line printer.

Two optional I/O devices announced with the system were the Model 0875 9-track tape drive (available in 800 bit./in NRZI or 1,600 bit/in. phase-encoded versions), and the Model 8421 "free-standing diskette drive".

ITW switches

This keyboard uses ITW magnetic valve switches, a type of electromagnetic switch patented by ITW (Illinois Tool Works Inc.) in 1974 and manufactured by ITW and Devlin.

The switches are contactless and rely on magnets to enable/disable electromagnetic induction across two contacts. The patent in question is probably this one if you want to delve into the details.

Let me shamelessly include a full passage from the Deskthority wiki:

ITW filed a patent for their magnetic valve switch in 1974. The tooling was later sold to Devlin; these Devlin-made switches are reported to have been very popular in the newspaper editing industry, with most European and North American newspapers specifying them across their operations. Devlin ended production of them in 2005, choosing to use only Cherry MX switches. Devlin referred to these switches as "Cortron" switches. No further details are known, as all documentation was disposed of (along with the tooling) at the termination of production.

UDS-2000

From the UDS-2000 brochure:

The SPERRY UNIVAC Universal Distributed System 2000 provides the cost-effective advantages and benefits of a computer-assisted, distributed data-capture in a system of up to four workstations.

Wanna see how cool that four-workstation setup looked like in 1978? Here you go:

(Are those slots in the desk 8" floppy disk drives?)

By the way, the purchase price for an entry-level UDS 2000 system, with 32Kb memory and a single "keystation", was $9,798. A version with three stations and a 200 char/sec printer cost $25,262 from the company (source).

Just imagine the magnificent cacophony with all the tape/floppy drives, huge printers, and of course the magnetic switches. Like this one:

IBM CANPOS

Sharktastica posted an IBM CANPOS (Compact Alphanumeric Point Of Sale) keyboard with a pointing stick.

The IBM CANPOS (Compact Alphanumeric Point Of Sale) keyboard, a compacted full-size buckling sleeve "Model M-e" keyboard with a pointing stick was posted by Sharktastica.

Whilst not TrackPoint, it's at least Synaptic TouchStyk (so, same tech as SK-8835, 8840 and 8845 series).

Admiral Shark has some photos of the TouchStyk module here:

Photos of its TouchStyk module! Anyone who has taken apart an SK-8835/8840/8845 will be familiar with these. pic.twitter.com/P74fO2nbrT

— Admiral Shark's Keyboards (@AdmSharksKeebs) April 30, 2022

This 133-key board was introduced in 2003.

In addition, in the process of revamping his Model F & Model M buyer's guide, Shark published the first major accomplishment: Model F versus Model M!

This is aimed towards first-time buyers not pros, hence only the bare minimum technical stuff is actually said.

Datadesk LittleFingers

After buying a Datadesk LittleFingers LF-2100 keyboard, FansForFlorida posted an informative gallery.

FansForFlorida bought a Datadesk LittleFingers LF-2100 keyboard on eBay, compared it to a Ducky One 2 TKL for scale, and posted lots of photos and info on Imgur.

This way: https://imgur.com/gallery/FHVbvxR

But why am I reposting a rubberdome keyboard?

Because Datadesk designed the LittleFingers specifically for children's smaller hands and fingers.

Look at FansForFlorida's comparison:

From the product page:

Now your K-6 students can master the computer without having to master a "wrong-sized" keyboard! We've reduced a fully functioning keyboard to enhance your students' ability to learn proper computing and keyboarding skills. The result? LittleFingers® — the first and only keyboard designed especially for kids' hands (source).

While there are USB versions, the original Littlefingers was available with either a built-in trackball (LF-2000) or number pad (LF-2100) and was compatible with PC and Mac via PS/2 and ADB connectors. (A switch on the back selected between PC and Mac modes.)

Apart from the strange arrow cluster, which is plain cruel, the concept is pretty reasonable. A lot of musical instruments with reduced sizes are manufactured for kids so why not make a smaller keyboard?

The Alps mount keycaps are 14.5mm wide so the "littlefinger-spacing" could be about 15mm.

Much smaller than the 19.05mm standard or the 18x17mm (17.5x16.5mm caps) Choc – or better said MBK – spacing.

PD_DECK

PD_DECK is a hot macropad by Monksoffunk primarily to control Lightroom.

PD_DECK by @monksoffunkJP is a controller prototyle, similar to Loupedeck, with QMK support.

With the settings for Lightroom Classic, that are included by default, you can adjust exposure and black or highlight with the knobs at the same time.

When adjusting the HSL (color) values, each color component is displayed on the LED next to the knob (in addition to the OLED).

Since signals from any MIDI controller can be sent to Lightroom to control an image's parameters, i.e. Lightroom Classic is operated via MIDI, the PD_DECK can actually be used for other things that can be tampered with MIDI as well, such as mixers and sound sources.

(By default, Lightroom is on layer 1, and layers 2-4 are free.)

The OLED font you can see in the picture above is also one designed specifically for the PD_DECK project.

Features

• Plateless design with PCB sandwich structure
• Middle layer is 3D printed (photo) or acrylic
• Onboard MCU (ATMega32u4), SMD parts mounted
• SK6812mini-e LEDs
• The switch is Kailh Choc v1 (v2 can be used too)

KEEB_PD

Btw, the "PD" part in the name refers to "photo duel".

It makes sense for a dedicated macropad or controller for a photo editing software but in fact it has a double meaning this time.

Every Sunday, from 19:00-21:00 JST, KEEB_PD is an event where people just post cool keyboard photos on Twitter.

Check out all the posts with this hashtag: https://twitter.com/hashtag/KEEB_PD

I wanted a controller for Lightroom that would be useful for this event, so I made one. This project was also an experiment to see if I could get the 9 encoders to read correctly – @monksoffunkJP.

MIDI in QMK: https://docs.qmk.fm/#/feature_midi

PD_DECK Discord channel: https://discord.gg/FeDYmYYRsw