General Info

Keyboard

A keyboard simply converts keystrokes (user input) into input commands, usually by stringing together a collection of character inputs.

Beyond the simple function of registering keystrokes, everything in the hobby is optimized for sound and feel. As you will see, a common theme for sound improvement comes from dampening/compression, and any form of reduction in rattle/instability.

Keyboard Matrix (Multiplexing)

The keyboard matrix is the fundamental idea behind the operation of any and all keyboard-adjacent input devices.

Keyboard Anatomy

Alt text

source: https://geekhack.org/index.php?topic=125072.0

Component	Description
Case	Houses the keyboard
Plate	Found in most keyboard designs. It provides stability to the PCB-Switch assembly
Keyswitch	The user interfaces with the keyswitch to register inputs
PCB	Connects the electronic components of the keyboard
MCU	The brains of the keyboard. Often integrated into the PCB

Case Design

Layout

The layout determines the general form factor of the case.

Mounting System

The way the PCB-switch assembly are housed within the case.

Courtesy of https://www.keyboard.university/200-courses/keyboard-mounting-styles-4lpp7

Switches

Keyboard switches are a very intriguing corner of the keyboard hobby, filled with some of the most bizarre naming schemes out of any hobby I’ve been a part of. The Keyboard switch rabbithole is vast and deep. Switch selection may impact the design of your pcb (potentially even the case), as switches may possess a unique form factor that you need to account for.

Switch Types

Cherry MX Style

Invented by Cherry in the 1980s, the MX style switch became the gold standard high-end switch solution. The MX style switch was a major innovation because it introduced a modular, customizable, and reliable mechanical keyboard switch. This design enabled a wide variety of tactile and auditory feedback options, and the durability of the switches allowed them to withstand millions of keystrokes. Most of the keyboard ecosystem is built around housing this style of switch.

Switch Anatomy

Alt text Stem: What is pushed down to trigger a key press.
Top Housing & Bottom Housing: Houses the switch assembly
Spring: Dampens the keypress and allows the key to return to starting position on the upstroke
Metal Leaf: Contact leaf that triggers the key input that registers a keypress

Manufacturers: The Switch Market

Cherry MX: The original switch manufacturer. Cherry MX switches come with a signature scratch that people have come to know and love. In a hobby that glorifies smoothness in all aspects of the typing experience, it’s interesting that the uniquely scratchy feeling of MX switches have withstood the test of time.

Cherry MX Blacks: MX blacks are an iconic switch, inspiring countless spinoffs such as OP blacks, MX Hyperglide. Old MX blacks (known as “vintage blacks”) that used the 1st gen tooling of Cherry MX Blacks (1984 - 1994) are sometimes harvested from old computers and repurposed due to their improved level of smoothness by nature of being “broken-in” from constant wear. There was also an alleged 1994 retool that made the switch worse in terms of smoothness, making the older MX blacks superior/more valuable in that regard.

Successors: Since Cherry dropped their switch patent in 2004, the manufacturer market has exploded with countless switch variations from a whole host of manufacturers.

Gateron: probably the most notorious Cherry MX clone company
- Milky Yellows, Deeping, Oil Kings, Black ink
Other Manufacturers: Kailh, JWK/Durock, KTT, Tecsee, Outemu, SP-star, Akko, BSUN/YOK, HMX, Everglide

Frankenswitches

Combining components from various switches to create a completely unique switch
Notable examples: Black Cherry Pie, Creamsicle, Zyko, Holy Boba, Holy Panda

ℹ️ Honorable Mentions
NK creams, Holy Pandas (Spinoffs: GOK Pandas, Glorious Pandas), Boba U4T, Tangies

Other Switch Types

Less popular switch types

Low profile

Low profile switches are most often seen in split keyboard builds.
Alt text

Choc switches
Choc v2

Cherry Ultra low profile
Alt text

Alps

Alt text A popular switch in the 80s and 90s. They became obsolete as Cherry rose in popularity.

SKCL (Linear): green, yellow
SKCM (Tactile, Clicky):
- Tactile: orange, salmon, black, cream/ivory, brown, neon green (rare)
- Clicky: blue, amber, white
Clones: Matias

Hall effect

Alt text Uses a magnetic field to detect keystrokes. The switch is gaining popularity in the gaming space, as there is a lot of software configurability as to when to detect inputs depending the distance of travel of the keystroke (along the downstroke and upstroke).

Lekker Switches (V2), Black Knight Switches, TTC Magneto Switch, OG Jades, Jade Pros, & Jade Max, Geon RAW HE

EC

Alt text The EC switch uses electrostatic capacitance to register an input. When the switch is pressed, two contact leaves are brought into close proximity. The electric field between the two contacts leaves becomes disrupted when the distance between them changes. This change in the electrostatic capacitance is measured to actuate the key.

AEBoards: Navy switches
Varmilo: Iris, Sakura, Ivy, Daisy, Rose

Topre
The Topre switch is distinctive, developing a cult following.

Alt text

Sound Profile

Linear: The stem freely moves through the switch cavity, offering a smooth consistent key press. Pretty self explanatory, and the most used form of switch.

Tactile: The signature key feel of a tactile switch is that it offers a tactile bump along the key press. The force actuation curve is nonlinear, in that at the middle of the key press, there is a noticeable point at which a large spike in actuation force is required.

Clicky: Beyond having a tactile bump along the key press, audible click sound is also produced. The click is produced when the key stem comes in contact with a click jacket or click bar along the key press.

Silent: Silent switches have dampening rubber on the feet of the stem and on the shoulders to both silence the bottom out as well as the upstroke.

Switch Materials

Switch material can impact the acoustic resonance of the switch upon key press. Common switch materials include POM, Nylon, HPE, and UMWHE.

Stabilizers

Keys larger than the typical 1u form factor require stabilizers to support the entire length of the key. Stabilizers come in a few styles.

Plate-mount: clip into the plate
PCB-mount: mount directly to the PCB

Screw-in: attached to the PCB via screws.
Platemount (Clip-in): Clip into the PCB Screw-in stabilizers are the preferred choice as they produce less wobble. In this instance, wobble would mean a less pleasant sound and typing experience.

Owlstabs, Staebies, Durock, TX, Cherry Clip-in

Mods

Modifications on existing components to improve sound and feel.
Modding as an idea rose in popularity around 2020-22. In more recent times, most mods, specifically ones that add foam/dampeners, are often rejected as a cheap/shoddy remedy to the many pitfalls of a poor design or keyboard configuration. People are returning to a more purist approach to keyboard builds by perfecting the basics (little to no foam, properly tuned stabilizers)

Switch Mods

Lube: Not so much a mod as lubrication is standard procedure, and many switches come pre-lubed. However, people do prefer to lube their own switches. Common lube choices include Krytox 205G0 (thicker, for linear switches), Tribosys 3203 (thinner, for tactile switches), or a proprietary blend of lubes.
Spring swap: stock springs can be substituted for aftermarket options, greatly impacting key feel. Springs can vary in length, actuation force (g), and number of stages (some springs have 2 stages, creating a staged actuation curve). Common spring manufacturers include SPRiT, TX, and Geon.
Switch Films: Switch films are sandwhiched between the top and bottom housing of a switch to reduce housing wobble/vibration.
-“Broken-in”: Switches can be preemptively pressed for tens of thousands of keystrokes before being sold, to physically smoothen the switch mechanical friction (like how a river stream smoothens river rocks).
Switch pads: Poron pads that are placed between the PCB and the switch to reduce key wobble. Switch pads are a less popular mod that came as a biproduct of the foam craze that seeks to dampen and deepen a keyboard’s sound signature by any means necessary.

Stabilizer Mods

Holee
Band-Aid

Case Mods

Forcebreak
Tempest Mod
Gasket
Silicone

Firmware

QMK

My fork of QMK
Quantum Mechanical Keyboard (QMK) firmware is an improved version of the TMK firmware made by Hasu, with improved programmability and microcontroller compatibility. VIA builds upon QMK by offering a GUI with simplified/graphical layout firmware configuration and additional features such as plug and play (no flashing), RGB controls, switch tester, etc. QMK is general suitable for wired keyboard designs that employ Atmel AVR and ARM architecture. https://www.reddit.com/r/MechanicalKeyboards/comments/hjh61v/what_is_qmk/

ZMK

My fork of ZMK
ZMK Firmware is an open source (MIT) keyboard firmware built on the Zephyr™ Project Real Time Operating System (RTOS). ZMK’s goal is to provide a modern and powerful firmware that is designed for power-efficiency, flexibility, and broad hardware support. ZMK is capable of being used for both wired and wireless input devices. ZMK is easier to implement and support both wired(unibody) and wireless options ZMK is has greater compatibility, notably in wireless applications. However, users say ZMK lags slightly behind in terms of ease-of-use features. There is also TMK and KMK. TMK is mostly deprecated, and is a Circuit Python keyboard firmware. ZMK and QMK are the more common options.

Mouse

A mouse provides cursor control to navigate and interact with display elements.

Motion Sensor

The motion sensor is at the core of mouse function. It converts physical mouse movement to cursor movement. The sensor tracks translational movement, polling at a high frequency.

huano

Laser sensor: motion tracking via lasers. Largely obsolete by modern standards.
Optical Mice: motion tracking via LEDs

Sensor	Description
mx8650	Firmware
pmw3360
Pixart paw3395

Switches

huano

Omron D2F-01
Kailh GM2.0
Huano

Blue Shell Pink Dot
Transparent Red dot

TTC 80M, TTC gold
Zippy DF3P1
Kailong

Firmware

The open-source support from the community is far more limited for mice. https://github.com/biomurph/Mouse

MCU Selection

An MCU (Microcontroller Unit) is the computer commonly found in integrated circuits (ICs) that contains a processor core, memory, and programmable I/O peripherals. It is the brain of embedded systems, controlling various features and operations.

ISA (Instruction Set architecture): Defines the instruction set (the machine “language”) a processor can understand. Examples: ARM, RISC-V, AVR

Framework: A collection of libraries/packages/toolchains that enable development. Framework compatibility depends on the MCU’s processor core ISA and communications protocols. Examples: Arduino, Zephyr, Tensilica Xtensa

ESP32

Core: Dual-core Tensilica LX6 processor (up to 240 MHz)
Flash: Up to 16MB (depending on variant)
RAM: 520KB SRAM
GPIO: 34 digital I/O pins, with support for PWM, UART, SPI, I2C, ADC, DAC, etc.
Wireless:
- Wi-Fi (802.11 b/g/n)
- Bluetooth 4.2/Bluetooth LE
Communication:
- I2C, SPI, UART, CAN, SDIO
- PWM, DAC, ADC (12-bit)
Power: Multiple power modes for efficiency (can go as low as 5uA)
Extras:
- Built-in touch sensors
- Integrated hardware cryptographic accelerators (e.g., for secure boot, SSL)
- RTC for time-keeping
Compatibility: ESP-IDF, Arduino framework, MicroPython

Built-in Wi-Fi and BLE with decent performance for wireless peripherals. Power draw is high for battery-powered designs and GPIO matrix limitations require careful planning.

Alt text

Microcontroller	Description
Seeed Studio XIAO ESP32C3	Compact, minimal
ESP32-DevKitC	A versatile development board with multiple I/O options.
ESP32-PICO-KIT	Features a small footprint with essential peripherals.

ATmega32U4 (AVR family)

8-bit AVR architecture
32KB Flash memory for program storage
2.5KB SRAM
1KB EEPROM
USB: Built-in USB support (for HID, CDC, etc.)

Widely used in keyboards (e.g. Pro Micro) due to native USB HID support and strong support in QMK. Limited in RAM and speed, making it less ideal for wireless or complex peripherals.

Microcontroller	Description
SparkFun Pro Micro	A compact board with a 5V/16MHz configuration, widely supported in the keyboard community	g
Teensy 2.0	Known for its robust USB capabilities and compatibility with various keyboard firmware.
Adafruit ItsyBitsy 32u4	Offers a small footprint with additional GPIO pins, suitable for space-constrained designs.

RP2040 / RP2350

Core: Dual-core ARM Cortex-M0+ (up to 133 MHz)
Flash: 2MB of onboard QSPI Flash
RAM: 264KB SRAM
GPIO: 26 digital I/O pins, with support for PWM, UART, SPI, I2C, ADC
Communication: I2C, SPI, UART interfaces
USB: Native USB support (can act as USB device or host)

RP 2040: Dual-core, high-performance MCU with lots of GPIO and flexible PIO for custom protocols. No built-in USB HID bootloader or wireless, but great for wired designs with custom behavior. RP 2350: Designed to build on RP2040 strengths with better wireless and security

Alt text

Microcontroller	Description
Arduino Nano RP2040
Waveshare RP2040-Tiny
Raspberry Pi Pico

nrf52480

Core: ARM Cortex-M4 (up to 64 MHz, with a floating-point unit)
Flash: 1MB flash memory
RAM: 256KB SRAM
GPIO: 48 digital I/O pins, with support for PWM, UART, SPI, I2C, ADC
Communication:
- I2C, SPI, UART, PWM
- ADC, DAC, PDM (Pulse Density Modulation)
Power: Very low power consumption (typically in the uA range during sleep modes)
Wireless:
- Bluetooth 5.0 (BLE) (supports BLE, Bluetooth mesh, and direction finding)
- Thread and Zigbee
- Supports 2.4 GHz proprietary protocols (e.g., for custom wireless protocols)
Extras:
- USB 2.0 device support. USB HID support
- Built-in hardware encryption for secure communications (AES, ECC)
- Real-Time Counter (RTC) support for time-critical applications
Compatible Frameworks: Nordic SDK, Zephyr OS, Arduino, Mbed OS, MicroPython (community-supported)

Built-in Bluetooth Low Energy (BLE) support. Ideal for wireless keyboard projects requiring Bluetooth connectivity (ZMK firmware support)

Alt text

Microcontroller	Description
nice!nanov2
Seeed Studio XIAO nRF52840	Compact
Adafruit Feather nRF52840 Express
SparkFun Pro nRF52840 Mini

STM32 Family

Core: ARM Cortex-M cores (M0, M0+, M3, M4, M7, M33, etc.), with a variety of clock speeds and performance levels.
Flash Memory: Varies from small (16KB) to large (up to 2MB) flash memory options, depending on the series.
RAM: Varies from small (4KB) to large (up to 1MB) SRAM.
GPIO: A wide range of GPIO pins, usually between 16 and 100+ pins.
Communication: Supports many communication interfaces like I2C, SPI, UART, CAN, USB, and Ethernet, depending on the series.
Power: Offers various low-power modes to extend battery life in portable devices.
Extras:
- Timers: Numerous general-purpose and advanced timers for PWM, motor control, and time-critical applications.
- Analog: Typically includes ADC (up to 12-bit), DAC, op-amps, and comparators.
- Security: Some models include cryptographic accelerators, secure boot, and hardware random number generators.
Compatible Frameworks: STM32Cube, HAL (Hardware Abstraction Layer), Arduino (via STM32 core), FreeRTOS, and Zephyr OS.

Versatile ARM-based family with options that support USB HID. Steeper learning curve and less community support for keyboards compared to ATmega/RP2040, but good for custom wired builds.

Alt text

Microcontroller	Description
Blue Pill (STM32F103C8T6)	Affordable and widely used in DIY projects.
Black Pill (STM32F411CEU6)	Provides higher performance with more memory and faster processing.
STM32F072 Nucleo	Features native USB support, beneficial for HID devices
STM32 Nucleo-32	Compact board with Arduino Nano compatibility

Honorable Mention: Teensy microcontrollers

Teensy 4.0

NXP iMXRT1062 microcontroller chip
Core: ARM Cortex-M7 processor operating at 600 MHz.

Alt text

A very capable microcontroller

Keyboards

I initially fell into the keyboard hobby during COVID when I was glued to my desktop and keyboard like most folks. My interest in industrial design aesthetics and boundless creative expression has led me on a long creative path of keyboard design.

Design Inspiration

Hand-wired Macropad

Alt text

Specs

For my first design, I kept it simple.

4x4 Matrix
Unibody construction

Model

Layout

Alt text

Components

Component	Description
Pro Micro nRF52840	Cheap alternative to nice!nanov2. BLE and lipo charging capability
DO-35 IN4148 High-speed Switching Diodes	Prevent ghosting (when multiple, unintended key presses register as a single press when multiple keys are pressed simultaneously. Diodes ensure that the current only flows in one direction, preventing unintended paths through the matrix when multiple switches are closed)
Heat shrink	Electrical isolation between rows and columns
1.5mm Bare Copper wire	Wiring to form rows and columns
JWK Black T1 Tactile Switches	Switches
250 mAh LiPo	Rechargeability
Housing	3D printed using PLA

Pin Mapping

Alt text

Build Log

4-10-25: Resized to fit a battery

3-25-25: Added keycaps

3-20-25: Completed the wiring

3-18-25: Hot-glued the switches in place

3-14-25: Made dimension modifications better suited to the design

8-21-24: Test fit JWICK tactiles

Macropad with PCB

PCB

KiCAD Alt text

Build Log

4-11-25: PCB Prototype

Ergo Split

Alt text

Specs

Low profile switches
Tenting via magsafe phone stands
Ergonomic splayed key spacing

Components

Component	Description
Magsafe phone stand x2	Tenting
Magsafe ring x2	Placed on keyboard to magnetically bind to stands
Choc Purple Switches	Switches
250 mAh LiPo Battery x2	Rechargeability
Housing	3D printed using PLA

Layout

Alt text

PCB

Designed in KiCAD Alt text

Build Log

3-14-25:

Ortho

Sleek

Alt text

Specs

Ortholinear key spacing
Ultra low profile switches

Components

Component	Description
Housing	3D printed using PLA

Layout

Alt text

PCB

Alt text

Build Log

3-14-25:

40% with Fkeys

A 40% keyboard with extra flare.

Alt text

Specs

Layout: 40% with function keys left side
PCB: mill max sockets
Case
- thin side bezels
- 2 piece construction
- top mount
- rectangular rubber feet
- low front height (cherry lip)

Components

Component	Description
1.5mm Bare Copper wire	Wiring to form rows and columns
JWK Black T1 Tactile Switches	Switches
250 mAh LiPo Battery	Rechargeability
Housing	3D printed using PLA