Within the realm of computer keyboards, a remarkable open-source firmware called KMK has surfaced, captivating enthusiasts from all corners. KMK possesses a potent capability to revolutionize mechanical keyboards into personalized instruments, enabling users to venture into uncharted territories of customization and productivity.
KMK Open Source Mechanical Keyboard Firmware Written in CircuitPython
CircuitPython is an open-source programming language that runs on microcontrollers used in various embedded applications, including mechanical keyboards like ANAVI Macro Pad 12 and ANAVI Arrows from our crowdfunding campaign at Crowd Supply. Built upon the foundations of Python, CircuitPython is specifically crafted to cater to the requirements of resource-limited embedded devices housing microcontrollers. One of the standout merits of CircuitPython lies in its user-friendly nature and effortless adaptability, particularly beneficial for newcomers who may not possess extensive coding expertise.
ANAVI Arrows and ANAVI Macro Pad 12 with the open source firmware KMK written in CircuitPython
The source code of KMK is readily available on GitHub, released under the GPLv3 license. The inception of KMK can be traced back to 2018. Notably, the KMK source code follows a coding style that employs the Python code formatter, known as Black, and embraces the usage of single quotes.
KMK firmware runs on Raspberry Pi RP2040 microcontoller which is in the core of Seeed Studio XIAO RP2040 module
The hardware requirements for microcontrollers to run KMK are: a minimum of 256KB of flash storage, support HID over USB and/or Bluetooth, CircuitPython version 7.0 or newer. With its impressive hardware capabilities, the Raspberry Pi RP2040 microcontroller is a perfect fit for CircuitPython and KMK. Because of this we selected Seeed Studio’s XIAO module with RP2040 for ANAVI Macro Pad 12 and ANAVI Arrows.
KMK offers many key features:
Key Mapping: Customize key assignments to suit individual preferences
Macros: Create and assign macros for automating tasks or executing commands
Layers: Define multiple virtual layers for accessing different functions or modes
LED Control: Customize backlighting and LED behavior
Rotary Encoder: Rotary encoders for various functions like volume control or scrolling.
Mini OLED Display: Compatibility with mini OLED displays, allowing users to display custom information or visuals on their keyboards
Back-light and under-light effects with KMK firmware on the mechanical keyboards ANAVI Macro Pad 12 and ANAVI Arrows
A standout feature of the ANAVI Macro Pad 12 and ANAVI Arrows is their seamless switch swapping capability, allowing you to tailor your typing experience on the go! With utmost ease and no need for soldering, thanks to the convenient hot-swappable sockets integrated into the printed circuit board, anyone can effortlessly remove a switch from its socket and replace it with another compatible switch.
This revolutionary feature provides several benefits to keyboard enthusiasts and users who like to customize their typing experience. It allows for easy experimentation with different switch types, enabling users to find the switch that suits their preferences best. It also simplifies switch replacement, making it more convenient to replace a faulty switch or try out different switches without needing specialized soldering equipment or skills.
Basically the whole key is like a sandwich: hot-swappable socket, mechanical switch and a keycap. All kits with ANAVI Macro Pad 12 and ANAVI Arrows include Gateron red mechanical switches. However thanks to the hot-swappable sockets you can experiment with various options of clicky, tactile and linear Cherry MX compatible mechanical switches from different brands with various tech specs and colors: red, blue, brown, green, silver, etc.
The printed circuit boards of ANAVI Macro Pad 12 and ANAVI Arrows are designed with Kailh hot-swap sockets on the back. These sockets are for surface-mount technology (SMT) assembly. To provide backlight on the front of the printed circuit boards there is a separate LED under each mechanical switch. We decided to make both of these keyboards with north-facing switches, aka the LED on each key is on the top (north) part of the switch. Furthermore, there are WS2812B addressable LEDs on the back. All these LEDs combined with the translucent keycaps included in the kit create awesome light effects when the keyboard is turned on. The open source firmware KMK allows fine tuning of the lights.
Although, as you can see in the video it is possible to hand-solder the sockets, this is appropriate only for a prototype. For manufacturing the keyboards ordered from the crowdfunding campaign we have hired a trusted local factory and they will do a professional lead-free assembly of all components. Using these hot-swappable sockets and SMT LEDs there is no need of manual hand soldering of any mechanical switches. This significantly simplifies and speeds up the manufacturing process. The end result is better quality and lower price.
Our crowdfunding campaign has a very modest goal of just $1. It will help us make the keyboards in my hometown Plovdiv, Bulgaria, EU thanks to the trusted supply chain we have established throughout the years. Order ANAVI Macro Pad 12 or ANAVI Arrows to get a cool mechanical keyboard and help us bring these entirely open source hardware projects to life!
Both ANAVI Macro Pad 12 and ANAVI Arrows feature high-quality gold-plated circuit boards designed with the free and open source software KiCad. These compact keyboards are driven by the Seeed Studio XIAO RP2040 with Raspberry Pi RP2040 microcontroller, ensuring top-notch performance. Equipped with a USB-C connector and a charming mini yellow-blue OLED display, they combine functionality with visual appeal. Thanks to the popular open-source KMK firmware written in CircuitPython, personalizing keyboard layouts and macros becomes a breeze.
ANAVI Arrows
Import your typing experience with our bright and shiny compact mechanical keyboards, made in Plovdiv, Bulgaria, EU. Support our crowdfunding campaign and help us bring these unique and high-quality open source keyboards to life.
There are two different options for mechanical keyboard open source firmware for ANAVI Macro Pad 10, Knobs 3, and Knob 1: KMK and QMK. Both of which have been getting upgrades recently!
KMK is a feature-rich and beginner-friendly open source firmware for mechanical keyboards, written in CircuitPython, which comes preloaded on the Macro Pad 10 and Knobs 1 and 3. The source code is available on GitHub under the GPLv3 license. So… if you have code suggestions to make it better, just open a GitHub pull request. This is exactly what Stefan Misch recently did, by improving the encoder resolution.
ANAVI Macro Pad 10, ANAVI Knobs 3 and ANAVI Knob 1
Huge thanks to Stefan for his valuable contribution to the upstream of KMK! If you own Macro Pad 10, Knobs 3, and Knob 1, please consider upgrading the KMK firmware on your mini mechanical keyboard to get his fix.
In other news: the GitHub pull request that adds support for ANAVI Knobs 3 was finally merged in QMK! QMK stands for Quantum Mechanical Keyboard. It is probably the most popular firmware for mechanical keyboards and supports literally hundreds of devices, including ANAVI Macro Pad 8 and our other mechanical keyboards. The source code is available under GPLv2 license and written in C. Initial support for the Raspberry Pi RP2040 microcontroller in QMK was added in September 2022. We started the porting efforts in October, and shortly after that, patches for ANAVI Macro Pad 10 and Knob 1 were merged. However, it took almost 6 months to merge the GitHub pull request for ANAVI Knobs 3. The long wait is over: now all of our mini mechanical keyboards are supported by QMK!
ANAVI Knobs 3
The community is very important and makes all the difference in any open source project. Thank you for supporting and improving our open source hardware mechanical keyboards!
As part of the certification program, OSHWA ensures that the definition of “open source hardware” used by a specific project (in our case in these 3 mini mechanical keyboards) matches the community’s definition of open source hardware. They provide a unique identification number (UID) for each version of the certified open hardware device based on the country code and a number. So now we have:
The prefix BG is the country code for Bulgaria, because all these mini mechanical keyboards are made in my hometown of Plovdiv, Bulgaria. As truly and entirely open source projects, we also go one step further. Only free and open source software has been used to design the printed circuit board, the stickers, the firmware, and the documentation. In previous updates we explained how we use KiCad for designing the printed circuit boards and the open source firmware QMK and KMK written in CircuitPython.
As part of the covered stretch goals, each kit will include stickers from ANAVI Technology and KiCad, the free and open source CAD software used for designing the printed circuit boards of the keyboards. Furthermore, ANAVI Macro Pad 10 kits will include 32 super-cool emoji stickers. You can stick them on the top or sides of the translucent keycaps. Last but not least, we’ll be publishing various video tutorials to ensure getting started is easy.
One more thing… Recently, our mini mechanical keyboards were featured in an article by CNX Software. This is a very popular website with news and tutorials about embedded systems, makers, and open source hardware. It was started in 2010 by Jean-Luc Aufranc. By the way it is worth keep an eye on CNX Software because there are always news about interesting gadgets!
ANAVI Knob 1, ANAVI Knobs 3 and ANAVI Macro Pad 10
ANAVI Macro Pad 10, ANAVI Knobs 3 and ANAVI Knob 1 all come with gold-plated black printed circuit boards, Raspberry Pi RP2040 microcontrollers, USB-C connector and clickable rotary encoders. The popular open source KMK firmware allows you to easily program and configure custom keyboard layouts and macros using CircuitPython.
The printed circuit boards still on panels before adding the EEPROM
The printed circuit board of ANAVI Info uHAT has a green solder mask and a gold surface finish. There are a few steps more to complete the manufacturing process. An EEPROM has to be flashed and soldered on each board. It will contain software description of the add-on board following Raspberry Pi Foundation’s HAT (Hardware Attached on Top) specifications. After that each board will go through a quality assurance, and finally each kit will be packaged in a recyclable cardboard box.
Panels with ANAVI Info uHAT
Low-volume manufacturing is not an easy task nowadays, especially during a global chip shortage. As usual we will keep you updated. Thank you again for supporting ANAVI Info uHAT!
I2C stands for Inter-Integrated Circuit, pronounced eye-squared-C, and alternatively known as IIC. It is a synchronous, multi-controller/multi-target (controller/target), packet switched, single-ended, serial communication bus. This protocol is suitable for devices wired at short distances, no more than 2-3m. We use I2C in pretty much all our open source products: Internet of Things, mechanical keyboards and Raspberry Pi HATs.
I2C sensor modules attached to ANAVI Info uHAT
I2C was originally developed in 1982 by Philips. While that makes it 40 years old, it is still a very convenient and widely used bus. There are many I2C sensors and peripherals. It is in pretty much every smartphone, embedded electronics, microcontroller, personal computer and of course Raspberry Pi.
ANAVI Info uHAT with 4 slots for I2C sensors and mini OLED dsiplay
Actually, since the introduction of the famous 40-pin header in 2014, Raspberry Pi single board computers have not one but two I2C buses! We use them both on ANAVI Info uHAT and our other HATs. Th first I2C bus is on pins 3 and 5. On the ANAVI Info uHAT, it is used for the three I2C slots for sensors and the 4th dedicated slot for the mini OLED display.
The I2C bus on ANAVI Info uHAT in KiCad’s Schematic Layout Editor.
The second I2C bus is on pins 27 and 28 of the Raspberry Pi and is reserved exclusively for attaching an ID EEPROM. The ID EEPROM contains a software description of the hardware so the operating system on your Raspberry Pi can automatically identify the add-on board.
The EEPROM on ANAVI Info uHAT attached on the 2nd I2C bus
The I2C bus consists of two signals: SDA (Serial Data) is a data signal, SCL (Serial Clock) is a clock signal. I2C modules also need power, so the dedicated I2C connectors on the ANAVI Info uHAT and our other open source hardware provide two additional pins for VCC and GND. Typically, the VCC for the I2C connectors on our add-on boards for Raspberry Pi are 3.3V.
The I2C bus drivers are “open drain”, which means they can only pull the corresponding signal line at low level. They cannot drive it high. To restore the signal to high when no device is asserting it low, a pull-up resistor has to be added to each signal line. For example, on the ANAVI Info uHAT, we have 4.7K pull-up resistors R4 and R5 connected to SDA and SCL.
Resistor selection varies depending on the devices attached to the bus. In some specific use cases, further adjustment of the resistance value might be required. For systems with lots of devices or longer wires, smaller resistors are better.
How to Enable I2C on Raspberry Pi OS
Raspberry Pi OS, previously known as Raspbian, is the default and recommended Linux distribution for all models and versions of the Raspberry Pi single board computer. By default, I2C is not enabled. There are several ways to enable it, but probably the easiest is using the command-line tool raspi-config to perform few basic commands:
Open a terminal or login remotely via SSH to your Raspberry Pi and type in the following command: sudo raspi-config
Each I2C device must have a unique address. The I2C reference design has a 7-bit address space, although rarely it might be used with a 10-bit extension. The 7-bit addresses range from 0 to 127 (0 to 0x7F hexadecimal). This is a limitation because it is not possible to have two I2C devices with the same address on the same I2C bus. For example, the I2C address on the mini OLED display included in all ANAVI Info uHAT kits is 0x3C. From the software side, this address is used in the example Python 3 script to access the display.
Python3 script controlling the mini OLED display over I2C on ANAVI Info uHAT
For Linux distributions, including Raspberry Pi OS, there is a package with a heterogeneous set of I2C tools called i2c-tools. To install it on Raspberry Pi OS, open a terminal and execute: sudo apt install -y i2c-tools. Once you have it installed, you can list attached I2C devices by their addresses with i2cdetect. For example, if the HTU21 temperature and humidity sensor module is attached to the Raspberry Pi, the output will be:
