The Hardware Sequencer Edition

MiniStep ESP32-P4

MiniStep ESP32-P4 is the hardware edition of MiniStep: an advanced step sequencer with a high-resolution master clock, persistent pattern memory, and direct USB-MIDI communication. The Waveshare ESP32-P4-Module-DEV-KIT uses the AKAI APC mini mk2 as its controller and appears to the computer as MIDISEQ Bridge.

Unlike the macOS Swift application, the sequencer engine runs on the microcontroller. It handles timing, pattern playback, chaining, fills, evolution, live performance, and live recording without requiring a computer to run the sequencer itself. The computer remains the sound destination for the generated MIDI for now. Future hardware plans include audio output, a screen with rotary encoders, and support for Novation devices.

Waveshare ESP32 P4 running MiniStep

Controller map

The APC mini mk2 remains the hands-on interface for the hardware edition. The diagram below shows the normal, Shift, Scene, parameter-editor, pattern-preview, and live-mode controls.

APCmini mk2 MiniStep hardware map

8 tracks Current page · 8 steps

VolumePage 1

PanPage 2

SendPage 3

DevicePage 4

Scene / mute Track Length Rate Direction Euclidean Evolve Fill Performance Record Normal: mute
Hold Shift: scene mode

9 fadersMIDI CC 0–8

↓Pattern downBrowse / edit

↑Pattern upBrowse / edit

◀ResetShift: tempo −

▶Play / queueShift: tempo +

ShiftModifierEditor / chain

Mode map What the controls do in each state

Sequencer

Grid toggle steps · Scene mute tracks · Pages select A–D

Play start / pause · Reset rewind · ↑ ↓ pattern preview

Shift

Shift + step step parameters · Shift + page chain pages

Shift + 7 / 8 tempo down / up · hold Shift for Scene mode

Scene mode

1 length · 2 rate · 3 direction · 4 Euclidean

5 evolve · 6 fill · 7 live performance · 8 live record

Step editor

Columns 1–4: velocity, probability, repeats, ratchet variation.

Columns 5–8: sample tuning · ↑ ↓ octave · Shift close

Pattern preview

↑ ↓ browse slots · Grid / pages edit without interrupting playback.

Play save and start / queue · Reset discard · hold ↑ + ↓ overview

Live modes

Performance: the grid triggers eight sounds while the sequence continues.

Record: bottom row records; other rows erase, mute, select, and edit steps.

GridPress a pad to toggle a step. Shift + active step opens per-step expression.

PagesVolume, Pan, Send, and Device select pages 1–4. Add Shift to build a chain.

PatternsUp and Down browse 64 slots. Hold both for the pattern overview; Play starts or queues.

Scene buttonsMute individual rows. Shift + Stop All Clips toggles the 64-pad Performance Mode.

What is implemented

Eight tracks, 32 steps per track, across four hardware pages.
64 persistent pattern slots stored in the ESP32's internal flash.
Pattern preview, queueing, overview, chaining, and MIDI Program Change.
A shared high-resolution master clock with 20–300 BPM tempo control.
Per-track lengths, rates, directions, Euclidean density, Evolve, and fills.
Per-step velocity, probability, repeats, ratchet variation, and sample tuning.
Live Performance and quantized Live Record modes.
Track mutes that can be prepared while the transport is stopped.
APC fader CC output for eight tracks and the master channel.
USB-MIDI host input from the APC and class-compliant USB-MIDI output to the computer.

Connections

The APC connects to a USB-A expansion port on the Waveshare board. The board's USB1.1 Type-C connector connects to the computer as MIDISEQ Bridge. The separate CH343/UART Type-C connector is used for flashing and serial logs. Keep the board's USB_SEL jumper on HOST.

Current status

This is an active hardware prototype. External clock synchronization, controller-profile configuration, JSON import/export, and SD-card workflows remain planned. The current build is designed around the APC mini mk2 and outputs MIDI 1.0.

For the macOS application edition, see MiniStep.