This is a tiny project, that took about 2 days. It uses the “Bluepill” MCU board with small OLED display for info texts and has few buttons to toggle LED lights and relays for audio outputs.
✍️Motivation
For many years (seems about 20) I was using just old logic chips. And it felt ancient, so I finally decided to do it with bluepill. Having a small display is nice and informative. With many inputs and outputs left, there is still room for later changes. This “console” is very useful and has a place just left of my keyboard. Has no case yet, and I’m not sure if it will, I’m just covering it with a black cloth.
📂Sources
Sources are here. Actually just using that Arduino .ino since it’s a small project. I was editing code in VSCodium, then building and uploading using the worst Arduino IDE 1.8.19.
This is a nice gadget I made recently for controlling speed / power of my PC fans (all are 12cm, 12V, 3 pin, with RPM output). It has way more features than my old & basic 3 knob regulator which I used for over 15 years. And since this is open source (and I wrote it), it surely has and can have any feature (commercially unavailable, not even thought of, or way too expensive). Obviously it isn’t badly needed, that’s why I made it after so long.
I do not recommend Teensy 3 at all. All Teensy boards are quite expensive and aren’t that needed for a fan controller. I think a bluepill or blackpill would suffice and be much cheaper. More info and detail in my MCU tutorial. I simply used Teensy 3 since I had it available, doing nothing and I had code for it from my older keyboard firmware, so it was faster to adapt it.
✍️Motivation
For many years I was using just the simplest LM317T voltage regulators with 3 knobs (for 3 fan sets).
Obviously a basic analog fan controller is very simple and extremely useful. I had 3 knobs (5k logarithmic potentiometers) with LM317T (even with no capacitors or radiators), mounted in the 3½” floppy disk bay. It was working very well for years and I could still use it.
I did try once a Gelid Speedtouch 6, wasn’t very cheap, and it was hopeless. Even worse, when I realized that I can make a better one myself, like usually. Additionally, after being rather finished with my keyboard features, I had some Teensy 3.2 boards left, lying around, doing nothing, simply asking to be used for something. Even better, I could use my older keyboard firmware for Teensy 3.2 and adapt it fast for this controller.
So I finally got to creating it. I called it “Fancy” from Fan C(ontroller). There was something new to learn too. I even used a cool circuit simulator to find out resistors around transistor, wasn’t exactly the real value later though.
And of course not everything went as planned.
For example: I wanted to use thermocouples for temperature which I had few of already. I tried an op-amp with differential amplifier for them and used ADC to read voltage which seemed working on breadboard. But after doing that for real (and using bigger resistor values) something didn’t work and I saw noise. So after few days trying I dropped it and just used DS18B20. They are bigger (3pin package) but have more precise measurement (at higher cost too).
Unfortunately I also killed one Teensy 3.2 board by accident. I’m not even sure how. I’m guessing some 12V was still left on capacitors and I could touch 3.3V pins with it.
📊Features
A shorter, bulleted list of all features can be seen in sources readme with more detail on electronic parts and schematic (image here).
GUI
It has a 3×3 keyboard and a LCD color display (diagonal is 1.8″, 4.5 cm). I did years ago my keyboards this way, so it also came with 3 levels menu (GUI), many options and even full screen demos (why not). Of course it permanently saves all settings, in EEPROM.
📈Regulating
The main advantage of my digital fan controller is that it allows lower RPM than analog, which then makes PC slightly quieter. This is because a fan needs shortly higher power (voltage or PWM) to start, but can have it lower after it started rotating (I don’t mean the power started rotating ?).
Next, it monitors RPM (revolutions per minute). So a natural safety feature here is: stop prevention (or in general RPM guard). It can increase power shortly to start again, even if user picked too little power to spin, or something stopped the fan.
Additionally PWM outputs can be used, for fans that allow it. Actually all of my old PC fans didn’t work with PWM, so I had to also make analog outputs (channels) for them at some point. I don’t know if it could be more universal, these channels require some other parts. So it can control analog fans (changing constant voltage) and PWM fans (changing modulated pulse width at medium frequency).
Optionally, temperature is measured. It can be used as feedback to automatically set fan power. This is naturally useful if sensor is on (or near) the heating part which fan is cooling. Sure, this can be possible to do with some software, that came with PC motherboard, GPU or a separate program. But it may not work on Linux or have all of my custom features. During summer I had my fans set higher, also even did set them lower when I wasn’t using much CPU (e.g. playing games or building C++). So hopefully this feature will make controller do it now, not me.
Since the display is 160×128 pixels, it can show graphs of RPM or Temperature over time. Even few smaller at once, but with less detail.
⌛Conclusions
Well it was a cool project, not just with digital chips, I had to use transistors with other parts too. I’m glad that one of the boards I have unused got to do something everyday. I hope it will last long. After all, my old regulators were really basic and much easier to repair (which wasn’t needed). Surely this thing is heavy, probably has too many parts too, but it doesn’t matter. It’s not like my PC weight matters at all.
This is my newest keyboard controller software (based on my previous one) used in my keyboard CK9 (upgraded CK6), running on Teensy 4.0 with a 2.8″ color LCD display (320×240, ILI9341 chip).
Here are videos of keyboard CK9, showing most of K.C.4 on its display:
View – Short video of keyboard and closeup at display.
Demos – Showing all demos (in auto mode): Plasma, 3D Polyhedrons with diagonals, Wave, Fire (meh), 2D waving CK Logo with shadow, and old Rain.
Features – A detailed look at features, no voice or commentary though. Editing mappings, sequences, testing etc.
Link to my channel with all keyboard videos so far here.
📂Sources
My firmware sources are on github. It’s called K.C.4 (“Kacey”) simply from Keyboard Controller and 4 from Teensy version.
The readme with all key features is visible on github. Here is more practical description. At end of page I wrote a comparison from my previous version (for Teensy 3.2) and quickly with other controllers / keyboards.
📊Features
The current code features are (and were mostly present in my previous K.C. version):
Display with menu, where you can edit everything possible.
Mapping (key binding). So which USB code will the physical key send to PC when pressed. There is a pick list with all common keys (and internal functions, sequences, etc) to choose from when binding. It has group colors and group filter for easier orientation.
Keyboard layout drawn on display. Shown when editing mappings (for currently chosen layer). Has a cursor to move around between keys. It’s also possible to jump to a key by pressing it.
Layers. If you hold a key, whole keyboard layout changes giving you other keys. Kind of like the Fn keys on laptop but much more useful and customizable. A common feature of custom controllers. Locking layers is also possible, either by lock/unlock key, tapping layer key fast or holding it for longer. Of course can be disabled and delay parameters are changeable.
Mouse keys. Keys that will move mouse, press mouse buttons or scroll mouse wheel. Also featuring acceleration with parameters for it and speed in GUI.
Sequences aka Macros. Basically any key combinations (for key shortcuts) and any sequences of key presses (for e.g. passwords). I am showing sequence previews where possible too, so when editing Mappings (for a sequence key), when picking a key from list or Testing pressed keys (if a key runs a sequence). I am also showing in sequences View, all mapped keys that run selected sequence.
Sequence commands are just a further extension.
They are special commands (beside sequence keys), that e.g. wait for few seconds (0.1s resolution), or change how slow the sequence will run (1ms resolution, useful e.g. for putty).
Others allow putting comments (for sequence purpose), and hiding sequence from preview (e.g. for passwords).
There is also a command to run other sequence(s) from this one. Also a repeat command that will do sequence (keys) continuously, until interrupted. This is e.g. useful e.g. if you want to watch a video faster, skipping parts with arrow keys after a short delay or take screenshots while watching etc. Normal keys can be used when a sequence runs too.
All mouse actions are available as commands too. So for example you can press a key (for a sequence) that will press button or move mouse etc. I have this way a mouse gesture done.
Internal functions. Keys to e.g. dim brightness, toggle GUI, toggle LED light, quit sequence, lock/unlock layer, change default layer etc. This a direct way, faster than adjusting parameters in GUI.
Testing and Setup pages. Useful when developing and to check if everything is working properly. Scan setup is advanced and adjust which strobe delay, scan frequency, debounce time I need. Matrix page shows the 18×8 keyboard matrix, with my anti-ghosting code working and any issues from too low strobe delay. It now also features X marks on keys that are available in matrix but not present on layout, this makes locating new extra keys very easy.
Demos and Game. Were already present in previous version and even on the first tiny display I used (128×64 mono). Since I have a display, and a powerful MCU, they show their drawing possibilities. They got extended to new resolution with few added extras. Best shown on videos, links below.
Clock. With date (uses internal RTC, needs 3V battery). Also showing Temperature, read from attached DS18B20 1-wire sensor (optional).
Statistics. Clock also displays (on its extended pages) keyboard use statistics:
Uptime. Time since power on or plugged in USB.
Late hour background. Will start slowly showing top of display orange at 22:00 and every 0:30 min going more visible, being yellow after 0:00 (midnight). This is to notify and motivate me to go to sleep when I sit too long at night.
Active time. I.e. how long I use keyboard without a break (at least 5 min, can be adjusted). Changes color from value. This is helpful to know if I’m doing something too long on PC. After all, it is recommended to take 5 min breaks every hour, it is healthy for spine and hands.
Inactive time. The opposite. Useful to know how long was I away from PC (keyboard). Also changes color when over 1 hour. Meaning I probably should have turned it off, to save power.
Press/min. Typing frequency, so how much key presses are done every minute. A colored value on left, going e.g. red at 120, yellow starting at 50. Also a second value below with total average since power on, with slowly changed value. So it is useful and directly corresponds to how tired will hands be. It’d be great to keep this value below 50, but sadly writing any text (e.g. chat, email etc.) or playing a game makes it go even above 150.
Graphs. As a part of clock, they show history of using keyboard (key presses/minute in the past hours). Second one is for temperature history. There are 320 points on display width and parameters for how often a value is added to graph.
⌨️Keyboard CK9
I upgraded my 2018 keyboard CK6 with this bigger display and K.C.4 and it became CK9. I also added tiny extra keys, lots of them. Above Numpad, 2 rows of 8 or in other words 4 groups of 4. Surely will come handy for e.g. internal functions or could be extra F13-F24 keys for OS. The keyboard has visible tear on few keys already, well I use it since 2016 (was CK3 first). Nothing yet, compared to the 14 year old one (CK7/4/2).
✍️Motivation
My previous version of KC and keyboards with it were quite useful and the 1.8″ color display was good too. The keyboard drawn on screen was minimal. Keys with one letter/digit/symbol had a 5×7 font, but 2 letters needed a tiny 3×5 font. It worked, but didn’t look great. So the new display is bigger 2.8″ and has about 2x resolution (320×240 vs 160×128).
The main reason for this upgrade though was the new Teensy 4.0 with a MCU that runs at 600MHz. It seems to be the fastest one available (on a board with USB, ready to use). And is even way faster than all previous. I already didn’t like Arduino in 2014 when I got interested in MCUs (again), seemed like a stone age relic compared to Teensy 3, but today I can say they probably have computational power of a rock, when compared.
The result is constant 45 frames per second almost always. This is what 600MHz MCU with SPI set at 60MHz for this display does, while using DMA for transfers and double buffered drawing (one buffer is being sent by DMA to display, while MCU draws new frame in second buffer, at the same time).
⚖️Comparisons
Of course, there were many projects of using a big display with slow MCU even. A MCU not having enough RAM for screen buffer. But this means very low refresh rate (low Fps) and flickering (blinking when redrawn).
There are few open source keyboard controllers, I think none of them even have a display, and some still use ATmega 8bit MCUs. Their requirements for program and RAM (memories of a MCU) are minimal, way lower than mine. And the price will be lower too. But the main flaw coming from it, is having to compile on PC and upload to MCU after any change. This is a big nope for me.
📢Rants
So for me, this is now the present (not the future anymore). And well honestly, whenever I see a custom keyboard picture I’m just asking: “where’s the display?”. In addition, seeing Cherry MX or any switches turns me away immediately.
Because there is one more very important thing that is the light press modification. All my keyboards since 2005 have it and it’s just the default for me. Sadly all commercial keyboards are garbage in this matter and people continue to produce keyboards that have a tactile feel, 4mm travel and around 50 gram force to press. Well for me this is the middle ages era. This can cause injuries (Carpal Tunnel Syndrome). And I guess it feels awful for those having pain from using such keyboards.
For my modding process (of reducing rubber dome keys press force and travel) pictures are in this gallery and I made a video of it recently (it is CK5).
✅Summary table
For reference, here is a table with current status of all my keyboards, since start until present day:
Name
Assembly year
Original keyboard
Keys actuation
[gram force]
Notes
CK3 > CK6 > CK9
2016 > 2018 > 2020
A4 Tech KX-100
23 g
Cheaper, bit wobbly, but more keys
CK2 > CK4 > CK7
2005 > 2016 > 2018
Logitech Ultra X Flat
33 g
Stiff foil, old, extra keys
CK5, CK5b
2015, 2020
A4 Tech KV-300H
9-18 g
The lightest foil
CK1
2004
Logitech Ultra X Flat
25 g
First, old, had extra keys,
now only for testing, 1 row dead 💀
This is my own keyboard controller software used in my keyboards CK6 and CK7 (upgraded CK3 and CK4), running on Teensy 3.2 (or 3.1) with a color LCD display (160×128, ST7735 chip). It is continued in newer version with Teensy 4 and bigger display.
My firmware sources are here. I called it K.C. (aka “Kacey”) simply from Keyboard Controller. A catchy cool name for software is a thing, isn’t it.
The readme with all key features is visible on github too. Here will be a more practical description.
✍️Motivation
My previous keyboards CK3 and CK4 were quite useful. But there were few flaws that I wanted to improve. They had a very tiny display, sure it did the job, but wasn’t convenient to look at for longer. Since I based my code on existing kiibohd controller software, there were few problems. Any change in key bindings had to be done on PC, needed to build binary and upload it to MCU. That’s a long way to e.g. check if it’d be better if I swapped some keys. Not to mention doing it at work. Lastly, there were few bugs which I couldn’t spend more time trying to fix.
So, it’d be better indeed to start writing my own code. And that’s what I did. Right now I can’t find a reason not to use my controller code. Sure, it was easier back then to get started, knowing there is an open source keyboard controller and it runs on Teensy 3.1, this is how I got into it. My code surely doesn’t have stuff present in kiibohd like NKRO support, keyboard LEDs animations and other fancy things I will likely never need. But it now does have features I wanted and it wasn’t that difficult to code them.
📊Features
So the code features are:
Display with menu, where you can edit everything possible (that I needed so far).
Key bindings (mappings), i.e. what USB codes will the physical key send to PC when pressed. There is a pick list with all common keys (and internal functions) to choose from when binding. It has group colors and group filter for easier orientation.
Keyboard layout drawn on display. Shown when editing mappings. Has a cursor to move around between keys, can also jump to key by pressing it.
Layers. If you hold a key, whole keyboard layout changes giving you other keys. Kind of like the Fn keys on laptop but much more useful and customizable. Surely a common feature in custom controllers (like tmk or kiibohd).
Sequences aka Macros. Basically any key combinations (for key shortcuts) and any sequences of key presses (for e.g. passwords). Not typing passwords myself, when my keyboard could do it, was my first reason when starting with keyboard controllers back then. Sadly even in kiibohd you couldn’t change them without rebuild and upload. This then was possible in my fork of kiibohd. To be convenient, I am showing (short) sequence preview where possible. So when editing Mapping (for a sequence key), when picking a key from list or Testing pressed keys (if a key runs a sequence). I am also showing in sequences view any mapped keys that run selected sequence.
Sequence commands are an even further extension. If you have an editor on display (basically a simpler editbox) one could put special commands (beside sequence keys), that e.g. wait for few seconds, or change how slow the sequence will run (useful for putty). Newest ones allow putting comments, useful if you have lots of sequences and want to rather see what it’s for, not what it will press. And hiding sequence from preview, useful if you don’t want to show important passwords on GUI.
Mouse keys, i.e. keys that will move mouse, press mouse buttons or scroll mouse wheel. Also featuring acceleration and even parameters for it and speed in GUI.
I now even have mouse commands with all mouse actions possible to add in sequences. Some stupid programs don’t allow everything using keyboard and specifically want you to click with mouse. But hey, now even this could be done automagically by my keyboard.
Testing and Setup pages. Those are quite useful when developing and in normal use to check if everything is working properly as intended. Scan setup is nice e.g. to check which strobe delay, scan frequency, debounce time I need. Matrix page shows the 18×8 keyboard matrix, with my anti-ghosting code working and any issues from too low strobe delay.
Demos and Game. Were already present in my fork of kiibohd. Now extended with new presets to color display. Best shown on videos, links below.
Clock with date (internal RTC, needs 3V battery) optionally also showing Temperature, read from attached DS18B20 1-wire sensor.
Internal functions, e.g. to dim brightness or toggle GUI, by keys on other layer.
⌨️Keyboards CK6 and CK7
I then upgraded my 2016 keyboards CK3 and CK4 with bigger, color display (160×128 LCD, ST7735) and K.C. They now became CK6 and CK7. Apart from the new displays and my software, the keyboards are the same.
The CK7 is the oldest one, comes from CK4, which in fact was done from CK2 (2006) and is now 12 years old… Still doing fine. Well this proves then, that cutting and gluing rubber domes is nothing that would decrease the lifespan of a keyboard. Even recently folded keyboard foil since CK4 works okay.
▶️Videos
There are a few videos of my keyboard CK7, showing most of K.C. on its display:
View – Short video of keyboard and closeup at display.
Plasma – Quick and colorful show of presets of plasma fullscreen effect. It runs at 10-30 frames per second. Note that I overclocked Teensy 3.2 here at 120 MHz, HW SPI runs at 30MHz. My other keyboard CK6 has Teensy 3.1 at 144MHz, SPI at 24MHz, it gives about 1.5 Fps more here.
Demos – Showing rest of demos: 3D Polyhedrons with diagonals, Wave, Fire (not real) and the older ones: 2D waving CK Logo, Space, Balls, Fountain, Fonts.
Game – falling blocks (Sixtis), or my version of it. It has 11 game presets, generated blocks, possibly diagonal, with many parameters for custom games.
Features – A detailed look at features, no sound or descriptions though. Editing mappings, sequences, testing etc.
Link to my channel with electronics videos here, just from my keyboards.
☑️Summary
For reference, here is a table with current status of all my keyboards, since start until present day:
Name
Assembly year
Original keyboard
Keys actuation
[gram force]
Notes
CK3 > CK6 > CK9
2016 > 2018 > 2020
A4 Tech KX-100
23 g
Cheaper, bit wobbly, but more keys
CK2 > CK4 > CK7
2005 > 2016 > 2018
Logitech Ultra X Flat
33 g
Stiff foil, old, extra keys
CK5, CK5b
2015, 2020
A4 Tech KV-300H
9-18 g
The lightest foil
CK1
2004
Logitech Ultra X Flat
25 g
First, old, had extra keys,
now only for testing, 1 row dead 💀
The newer two of my heavily modified keyboards. This time having Teensy 3.1 (or 3.2) as microcontroller with a tiny 1″ monochrome OLED display. Firmware was based on Kiibohd, it was a fork with my extensions. I added display support (with a library), menu for editing e.g. macros/sequences, few demos and a game. I did improve them further in my newer firmware, with bigger display.
🛠️Modifications
The first operation I did, was cutting off most of all rubber domes. This makes the keys much softer to press, so needs less effort or fatigue. The result is minimized pressing (actuation) force and distance. Simply more pleasant and comfortable. Also healthier, since the risk of keyboard injuries decreases. I already did that earlier on my two oldest keyboards in 2005 and 2006.
✍️Motivation
Originally most keyboards need about 50 gram force needed to press keys, and probably 4 mm distance. After cutting, the distance is about 1-2mm, the force is at 23 gram for CK3 (top), 33g for CK4 (bottom) and 9-18g for CK5. This can also be varied per key (more detail can be seen on pictures (galleries below), but ultimately the lowest value depends on keyboard’s foil thickness.
⌨️Additional keys
For CK4 there are also few small extra keys. Which were present already in my earliest keyboards CK1 and CK2. Those are glued on top and are made from lightest 0,5N switches available. The row above numpad is used for my audio player control. Rest is custom. This part is optional and I didn’t do it for CK3. The disadvantage is the difference in pressing those switches and much lighter normal keyboard keys. They are smaller so you can fit more, but are less convenient to press. Lastly, regular keys can be used to switch layers instead.
⚙️Microcontroller (MCU)
The second step was replacing the keyboard controller board, with my own. The hardware is composed of Teensy 3.1 (or 3.2) with a tiny 1 inch OLED display (SSD1306, monochrome, 128×64) and a bunch of wires to connect to the original keyboard’s matrix.
The reason for this was to take advantage of already made open source Kiibohd controller allowing any imaginable keys assigned and layers. Also possible are macros, key combinations and even mouse buttons and movement simulation. But changing any of this required rebuilding controller software and uploading to controller, through already present USB.
It was a bit simpler to start at the time, instead of writing my own later.
📊Features
After getting it to work, I implemented my own menu where you can edit sequences, stored in memory (remembered after power off). The sequences are very useful for not typing passwords or simply binding some useful macro combinations or commands dynamically. Which needed a display and menu for entering.
Once I’ve done the useful stuff, I got carried away and implemented several demos on display and even a falling blocks game. I also wrote about it in this forum post.
📂Sources
The code is in my fork here with some more detail.
📷Galleries
There are picture galleries below, also from assembly and videos.▶
All galleries up to now, from my keyboards are as follows (newest first):
Most pictures have some description text (explaining what I did there).
This is the final version of the “console” I created around 2003. Its purpose was to serve as program memory for 8051 MCU (board with it is not yet attached on this picture). The PC was filling console’s memory with bytes of code and then starting MCU which used it as program code. Console was connected with a PC through parallel port (LPT). The PC had my own IDE (editor) and compiling its assembler code to bytes.
Nowadays this isn’t at all needed and even looks scary. MCUs of today have Flash memory for program, either programmed from PC through USB already or with a simple chip (USB to serial) converter/adapter/programmer.
📊Features
PC usually was sending a lot of bytes, so the console had counters, to increment the address by itself. It used power supply from PC, here 12V which LM317 regulator converted to 5V.
So its memory (SRAM, 256kbit) was filled by the PC through the console, it then would serve as program memory for the 8051 family MCUs (a quite popular one, but still poor, like ATmega328 today).
I had two modules for it. One with big 80C32 and second with smaller and faster 90C32. The console had a connector where you could attach one.
It also featured a relay that would automatically turn on the supply for the module once the program got transferred to memory.
Later you could switch the SRAM to EEPROM and get it programmed for the use in actual module/device with MCU, without console. Which I eventually never got to.
🔍Details
The console board was smaller than the older one (below) and needed less current. It featured a small and detachable display module, for showing address and byte value, which was mainly for checking and later wasn’t needed.
Construction was made on a universal board, possibly reused. Since being smaller it also was more durable and had less spaghetti wires. Underside actually looked very well compared to the mess in older version.
🖥️Program
The PC program was driving LPT port and sending code bytes to memory. It quickly became a basic IDE, where I could write code for ’51 MCU in its assembly language. I wrote it in Delphi 5, which I was using at that time a lot. It translated all instructions and computed jump offsets. Additionally with one key press it compiled assembly code to bytes, then sent it to console and triggered its relay to start the program with MCU module. That was the most convenient thing possible. I’ve seen too many solutions which needed pressing reset switch on the board or other slow, manual work.
👉Conclusions
I was trying out few things to get done, an 8 bit ADC, a real time clock HM6818A chip and mostly 5×7 dot matrices. It somehow didn’t feel too stable, and it was a lot work to get anything done at the time. I actually didn’t finish any board then, as a separate working MCU. For a clock it would use too much current. And for making anything else that MCU was too slow. And I was more interested in other things at the time like creating music and my tracker.
Lately everything I wanted back then, can be easily (and rather cheaply) done with modern MCUs connected through USB. Hence my recent interest got back into electronics and my keyboards even had a 128×64 display and even a 160×128 one later.
📜Older version
The first (older) version had bigger digits, mounted solid with also the logic to decode them. I think it was using close to 1A from 5V, and the 74192 counters were heating like crazy.
I was also using SMD chips, if I found them somewhere else and desoldered. I don’t have any picture from underside of this old version, but I remember it was a serious spaghetti. I’m guessing around 400 wires connected 😆.