https://reddit.com/link/1uhhwc7/video/l5lx4dzcww9h1/player

Hey, I made a toy!

It’s a MIDI controller made mainly for the Koala workflow, but it can also be used with other DAWs.

It is based on the Eucalyptus controller I made a few years ago, so I call this one EC-2.

It is battery powered, connects to a tablet or phone over BLE MIDI, and also works with USB MIDI. In this short demo it is connected to PC

Hardware

• 16 velocity-sensitive keyboard keys These are Hall effect magnetic keys. They trigger sensors on the PCB, and the controller reads the hit speed to simulate velocity/volume level. All of the pad buttons can be customized. In the setting menu accessed by long pressing the encoder you enter the menu where by pressing the pad you want to setup you choose midi number, type of message ( note, cc ,pc ). If CC is selected you can set the press and release value that pad sends.
• LED lights The LEDs light up when keys are pressed, and they change color when the channel is changed.
• 10 tactile buttons for fixed functions 9 buttons can be MIDI mapped, and one button is SHIFT for quick channel change. These buttons stay fixed on CH1 and do not change when the channel is changed for the pads, pots, and encoders. This allows them to be used for Play, Rec, Undo, Mute, Solo, and similar functions, independent of which channel you are using at the moment. In submenu you can select if these buttons send note or CC  and if  they are toggle ON/OFF 
• 6 potentiometers They send CC messages and have pot pickup, so they do not make unwanted jumps when switching channels. This means when you change the channel the pot  reading doesn’t start from the value from the previous channel but reads its value for a specific channel. When you get back to the previous channel you have to turn the pot to a memorized position to activate it. These pots send CC number value and can also be customized in the options section.
• 2 encoders They send CC values from 0 to 127, and they are also used to access the settings menu.
• Tiny OLED display The display shows the channel number, pot levels, active note number, setting selections, root notes, and scales for piano mode.
• XIAO ESP32-S3 Plus This is the brain of the device. It also has an LED indicator for Bluetooth connection.

Channels

There are 4 channels.

You can switch between them by holding SHIFT and pressing one of the 4 buttons in the group on the left. When the channel is changed, the LED lights change to the corresponding color, and the channel number is shown on the screen.

The first 3 channels are for mapping pads, pots, and encoders to Koala. This gives you 3 times more options than the visible hardware, plus some extra special options.

The fourth channel is reserved for piano mode. When you are on this channel, Encoder 1 sets the root note and Encoder 2 selects the scale preset, like chromatic, major, minor, and others, similar to the app.

A special feature is that when you hold SHIFT (while in any channel)  if you press any pad button it will trigger the pad in the next channel. This allows you to quickly trigger the specifically mapped  functions on the next channel without leaving the current channel. For example when in channel 2 that you set up to trigger  effects via CC messages you can access channel 3 and trigger solo or mute  buses on the mixer page.

Menu and MIDI Editing

When you are on any of the first 3 channels, long-pressing Encoder 1 enters the menu.

If you press any of the pads, you can change what type of MIDI message that pad sends. The default is Note, but you can switch it to CC or Program Change. The note can be changed to any MIDI note number and saved permanently.

If CC is selected, you can also choose what value is sent when the button is pressed and what value is sent when it is released. This is useful because the pads can be used as quick effect triggers.

For example, on Channel 2, I can choose Pad 13 and set it to CC, using the same CC number as the pot I use for stutter. I can set the press value to 20 and the release value to 0. While performing, if I press this pad, stutter jumps to 20. When I release it, it goes back to 0.

I can also choose Pad 14 and set the CC to the same number as the pot controlling the filter. Press value can be 127, and release value can be 64. When pressed, the filter jumps to the set value, and when released, it resets. Effects that go up and down from the middle of the bar should return to value 64 when released.

The same can be done for all effects.

Build and Repair

EC-2 is built around the XIAO ESP32-S3 Plus. It comes with firmware, but you can write your own code if you are up to it.

The device is also made to be easy to repair if needed. All you need is some soldering skill. The battery charging circuit is a separate module on purpose, so if it ever malfunctions, it can be replaced by soldering only a few pins.

The pads are standard keyboard Hall effect keys. They are very hard to break, and if they do break, they are cheap and easy to replace. The keycaps are also standard, so you can customize the look of the pads however you like.

Battery

The battery is a standard removable 18650 rechargeable lithium battery, available almost everywhere.

I chose this type of battery because the previous controller I made was more complicated to ship. Built-in lithium batteries can require extra paperwork or certificates because of possible fire hazard during postal handling.

Also, if the battery runs out while playing, you can quickly switch to a charged one if you have a spare.

If the controller is connected to a computer or phone by USB cable, the battery is not required.

I chose this design with portability in mind.

I have seen some musicians wanting a DAW-less Koala sampler, but my view is that if you want a sampler like that, you can just buy a hardware sampler.

My idea was to make a tool that extends Koala’s functionality and solves some of the limitations of using only one touchscreen. For example, playing samples and applying effects at the same time is much nicer with physical controls. Also, having velocity and the tactile feel of real buttons is just better.

I got myself an EP-133, but I still prefer Koala.

Many hardware controller manufacturers try to add touchscreens to their devices as a feature, but that also increases production cost and final price. With screens, there are also more things that can malfunction, and then the manufacturer has to provide service.

Koala is great because you already own your own big touchscreen.

So EC-2 is my idea of a small hardware companion for Koala: portable, repairable, customizable, and made for performance.