2020 November 28 Breaking Changes Update (#11053)

* Branch point for 2020 November 28 Breaking Change

* Remove matrix_col_t to allow MATRIX_ROWS > 32 (#10183)

* Add support for soft serial to ATmega32U2 (#10204)

* Change MIDI velocity implementation to allow direct control of velocity value (#9940)

* Add ability to build a subset of all keyboards based on platform.

* Actually use eeprom_driver_init().

* Make bootloader_jump weak for ChibiOS. (#10417)

* Joystick 16-bit support (#10439)

* Per-encoder resolutions (#10259)

* Share button state from mousekey to pointing_device (#10179)

* Add hotfix for chibios keyboards not wake (#10088)

* Add advanced/efficient RGB Matrix Indicators (#8564)

* Naming change.

* Support for STM32 GPIOF,G,H,I,J,K (#10206)

* Add milc as a dependency and remove the installed milc (#10563)

* ChibiOS upgrade: early init conversions (#10214)

* ChibiOS upgrade: configuration file migrator (#9952)

* Haptic and solenoid cleanup (#9700)

* XD75 cleanup (#10524)

* OLED display update interval support (#10388)

* Add definition based on currently-selected serial driver. (#10716)

* New feature: Retro Tapping per key (#10622)

* Allow for modification of output RGB values when using rgblight/rgb_matrix. (#10638)

* Add housekeeping task callbacks so that keyboards/keymaps are capable of executing code for each main loop iteration. (#10530)

* Rescale both ChibiOS and AVR backlighting.

* Reduce Helix keyboard build variation (#8669)

* Minor change to behavior allowing display updates to continue between task ticks (#10750)

* Some GPIO manipulations in matrix.c change to atomic. (#10491)

* qmk cformat (#10767)

* [Keyboard] Update the Speedo firmware for v3.0 (#10657)

* Maartenwut/Maarten namechange to evyd13/Evy (#10274)

* [quantum] combine repeated lines of code (#10837)

* Add step sequencer feature (#9703)

* aeboards/ext65 refactor (#10820)

* Refactor xelus/dawn60 for Rev2 later (#10584)

* add DEBUG_MATRIX_SCAN_RATE_ENABLE to common_features.mk (#10824)

* [Core] Added `add_oneshot_mods` & `del_oneshot_mods` (#10549)

* update chibios os usb for the otg driver (#8893)

* Remove HD44780 References, Part 4 (#10735)

* [Keyboard] Add Valor FRL TKL (+refactor) (#10512)

* Fix cursor position bug in oled_write_raw functions (#10800)

* Fixup version.h writing when using SKIP_VERSION=yes (#10972)

* Allow for certain code in the codebase assuming length of string. (#10974)

* Add AT90USB support for serial.c (#10706)

* Auto shift: support repeats and early registration (#9826)

* Rename ledmatrix.h to match .c file (#7949)

* Split RGB_MATRIX_ENABLE into _ENABLE and _DRIVER (#10231)

* Split LED_MATRIX_ENABLE into _ENABLE and _DRIVER (#10840)

* Merge point for 2020 Nov 28 Breaking Change

7 files changed, 1051 insertions, 0 deletions

diff --git a/quantum/sequencer/sequencer.c b/quantum/sequencer/sequencer.c
new file mode 100644
index 0000000000..0eaf3a17aa
--- /dev/null
+++ b/quantum/sequencer/sequencer.c
@@ -0,0 +1,275 @@
+/* Copyright 2020 Rodolphe Belouin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "sequencer.h"
+
+#ifdef MIDI_ENABLE
+#    include "process_midi.h"
+#endif
+
+#ifdef MIDI_MOCKED
+#    include "tests/midi_mock.h"
+#endif
+
+sequencer_config_t sequencer_config = {
+    false,     // enabled
+    {false},   // steps
+    {0},       // track notes
+    60,        // tempo
+    SQ_RES_4,  // resolution
+};
+
+sequencer_state_t sequencer_internal_state = {0, 0, 0, 0, SEQUENCER_PHASE_ATTACK};
+
+bool is_sequencer_on(void) { return sequencer_config.enabled; }
+
+void sequencer_on(void) {
+    dprintln("sequencer on");
+    sequencer_config.enabled               = true;
+    sequencer_internal_state.current_track = 0;
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.timer         = timer_read();
+    sequencer_internal_state.phase         = SEQUENCER_PHASE_ATTACK;
+}
+
+void sequencer_off(void) {
+    dprintln("sequencer off");
+    sequencer_config.enabled              = false;
+    sequencer_internal_state.current_step = 0;
+}
+
+void sequencer_toggle(void) {
+    if (is_sequencer_on()) {
+        sequencer_off();
+    } else {
+        sequencer_on();
+    }
+}
+
+void sequencer_set_track_notes(const uint16_t track_notes[SEQUENCER_TRACKS]) {
+    for (uint8_t i = 0; i < SEQUENCER_TRACKS; i++) {
+        sequencer_config.track_notes[i] = track_notes[i];
+    }
+}
+
+bool is_sequencer_track_active(uint8_t track) { return (sequencer_internal_state.active_tracks >> track) & true; }
+
+void sequencer_set_track_activation(uint8_t track, bool value) {
+    if (value) {
+        sequencer_internal_state.active_tracks |= (1 << track);
+    } else {
+        sequencer_internal_state.active_tracks &= ~(1 << track);
+    }
+    dprintf("sequencer: track %d is %s\n", track, value ? "active" : "inactive");
+}
+
+void sequencer_toggle_track_activation(uint8_t track) { sequencer_set_track_activation(track, !is_sequencer_track_active(track)); }
+
+void sequencer_toggle_single_active_track(uint8_t track) {
+    if (is_sequencer_track_active(track)) {
+        sequencer_internal_state.active_tracks = 0;
+    } else {
+        sequencer_internal_state.active_tracks = 1 << track;
+    }
+}
+
+bool is_sequencer_step_on(uint8_t step) { return step < SEQUENCER_STEPS && (sequencer_config.steps[step] & sequencer_internal_state.active_tracks) > 0; }
+
+bool is_sequencer_step_on_for_track(uint8_t step, uint8_t track) { return step < SEQUENCER_STEPS && (sequencer_config.steps[step] >> track) & true; }
+
+void sequencer_set_step(uint8_t step, bool value) {
+    if (step < SEQUENCER_STEPS) {
+        if (value) {
+            sequencer_config.steps[step] |= sequencer_internal_state.active_tracks;
+        } else {
+            sequencer_config.steps[step] &= ~sequencer_internal_state.active_tracks;
+        }
+        dprintf("sequencer: step %d is %s\n", step, value ? "on" : "off");
+    } else {
+        dprintf("sequencer: step %d is out of range\n", step);
+    }
+}
+
+void sequencer_toggle_step(uint8_t step) {
+    if (is_sequencer_step_on(step)) {
+        sequencer_set_step_off(step);
+    } else {
+        sequencer_set_step_on(step);
+    }
+}
+
+void sequencer_set_all_steps(bool value) {
+    for (uint8_t step = 0; step < SEQUENCER_STEPS; step++) {
+        if (value) {
+            sequencer_config.steps[step] |= sequencer_internal_state.active_tracks;
+        } else {
+            sequencer_config.steps[step] &= ~sequencer_internal_state.active_tracks;
+        }
+    }
+    dprintf("sequencer: all steps are %s\n", value ? "on" : "off");
+}
+
+uint8_t sequencer_get_tempo(void) { return sequencer_config.tempo; }
+
+void sequencer_set_tempo(uint8_t tempo) {
+    if (tempo > 0) {
+        sequencer_config.tempo = tempo;
+        dprintf("sequencer: tempo set to %d bpm\n", tempo);
+    } else {
+        dprintln("sequencer: cannot set tempo to 0");
+    }
+}
+
+void sequencer_increase_tempo(void) {
+    // Handling potential uint8_t overflow
+    if (sequencer_config.tempo < UINT8_MAX) {
+        sequencer_set_tempo(sequencer_config.tempo + 1);
+    } else {
+        dprintf("sequencer: cannot set tempo above %d\n", UINT8_MAX);
+    }
+}
+
+void sequencer_decrease_tempo(void) { sequencer_set_tempo(sequencer_config.tempo - 1); }
+
+sequencer_resolution_t sequencer_get_resolution(void) { return sequencer_config.resolution; }
+
+void sequencer_set_resolution(sequencer_resolution_t resolution) {
+    if (resolution >= 0 && resolution < SEQUENCER_RESOLUTIONS) {
+        sequencer_config.resolution = resolution;
+        dprintf("sequencer: resolution set to %d\n", resolution);
+    } else {
+        dprintf("sequencer: resolution %d is out of range\n", resolution);
+    }
+}
+
+void sequencer_increase_resolution(void) { sequencer_set_resolution(sequencer_config.resolution + 1); }
+
+void sequencer_decrease_resolution(void) { sequencer_set_resolution(sequencer_config.resolution - 1); }
+
+uint8_t sequencer_get_current_step(void) { return sequencer_internal_state.current_step; }
+
+void sequencer_phase_attack(void) {
+    dprintf("sequencer: step %d\n", sequencer_internal_state.current_step);
+    dprintf("sequencer: time %d\n", timer_read());
+
+    if (sequencer_internal_state.current_track == 0) {
+        sequencer_internal_state.timer = timer_read();
+    }
+
+    if (timer_elapsed(sequencer_internal_state.timer) < sequencer_internal_state.current_track * SEQUENCER_TRACK_THROTTLE) {
+        return;
+    }
+
+#if defined(MIDI_ENABLE) || defined(MIDI_MOCKED)
+    if (is_sequencer_step_on_for_track(sequencer_internal_state.current_step, sequencer_internal_state.current_track)) {
+        process_midi_basic_noteon(midi_compute_note(sequencer_config.track_notes[sequencer_internal_state.current_track]));
+    }
+#endif
+
+    if (sequencer_internal_state.current_track < SEQUENCER_TRACKS - 1) {
+        sequencer_internal_state.current_track++;
+    } else {
+        sequencer_internal_state.phase = SEQUENCER_PHASE_RELEASE;
+    }
+}
+
+void sequencer_phase_release(void) {
+    if (timer_elapsed(sequencer_internal_state.timer) < SEQUENCER_PHASE_RELEASE_TIMEOUT + sequencer_internal_state.current_track * SEQUENCER_TRACK_THROTTLE) {
+        return;
+    }
+#if defined(MIDI_ENABLE) || defined(MIDI_MOCKED)
+    if (is_sequencer_step_on_for_track(sequencer_internal_state.current_step, sequencer_internal_state.current_track)) {
+        process_midi_basic_noteoff(midi_compute_note(sequencer_config.track_notes[sequencer_internal_state.current_track]));
+    }
+#endif
+    if (sequencer_internal_state.current_track > 0) {
+        sequencer_internal_state.current_track--;
+    } else {
+        sequencer_internal_state.phase = SEQUENCER_PHASE_PAUSE;
+    }
+}
+
+void sequencer_phase_pause(void) {
+    if (timer_elapsed(sequencer_internal_state.timer) < sequencer_get_step_duration()) {
+        return;
+    }
+
+    sequencer_internal_state.current_step = (sequencer_internal_state.current_step + 1) % SEQUENCER_STEPS;
+    sequencer_internal_state.phase        = SEQUENCER_PHASE_ATTACK;
+}
+
+void matrix_scan_sequencer(void) {
+    if (!sequencer_config.enabled) {
+        return;
+    }
+
+    if (sequencer_internal_state.phase == SEQUENCER_PHASE_PAUSE) {
+        sequencer_phase_pause();
+    }
+
+    if (sequencer_internal_state.phase == SEQUENCER_PHASE_RELEASE) {
+        sequencer_phase_release();
+    }
+
+    if (sequencer_internal_state.phase == SEQUENCER_PHASE_ATTACK) {
+        sequencer_phase_attack();
+    }
+}
+
+uint16_t sequencer_get_beat_duration(void) { return get_beat_duration(sequencer_config.tempo); }
+
+uint16_t sequencer_get_step_duration(void) { return get_step_duration(sequencer_config.tempo, sequencer_config.resolution); }
+
+uint16_t get_beat_duration(uint8_t tempo) {
+    // Don’t crash in the unlikely case where the given tempo is 0
+    if (tempo == 0) {
+        return get_beat_duration(60);
+    }
+
+    /**
+     * Given
+     *  t = tempo and d = duration, both strictly greater than 0
+     * When
+     *  t beats / minute = 1 beat / d ms
+     * Then
+     *  t beats / 60000ms = 1 beat / d ms
+     *  d ms = 60000ms / t
+     */
+    return 60000 / tempo;
+}
+
+uint16_t get_step_duration(uint8_t tempo, sequencer_resolution_t resolution) {
+    /**
+     * Resolution cheatsheet:
+     * 1/2  => 2 steps per 4 beats
+     * 1/2T => 3 steps per 4 beats
+     * 1/4  => 4 steps per 4 beats
+     * 1/4T => 6 steps per 4 beats
+     * 1/8  => 8 steps per 4 beats
+     * 1/8T => 12 steps per 4 beats
+     * 1/16 => 16 steps per 4 beats
+     * 1/16T => 24 steps per 4 beats
+     * 1/32 => 32 steps per 4 beats
+     *
+     * The number of steps for binary resolutions follows the powers of 2.
+     * The ternary variants are simply 1.5x faster.
+     */
+    bool     is_binary            = resolution % 2 == 0;
+    uint8_t  binary_steps         = 2 << (resolution / 2);
+    uint16_t binary_step_duration = get_beat_duration(tempo) * 4 / binary_steps;
+
+    return is_binary ? binary_step_duration : 2 * binary_step_duration / 3;
+}
diff --git a/quantum/sequencer/sequencer.h b/quantum/sequencer/sequencer.h
new file mode 100644
index 0000000000..aeca7a1e9b
--- /dev/null
+++ b/quantum/sequencer/sequencer.h
@@ -0,0 +1,122 @@
+/* Copyright 2020 Rodolphe Belouin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include "debug.h"
+#include "timer.h"
+
+// Maximum number of steps: 256
+#ifndef SEQUENCER_STEPS
+#    define SEQUENCER_STEPS 16
+#endif
+
+// Maximum number of tracks: 8
+#ifndef SEQUENCER_TRACKS
+#    define SEQUENCER_TRACKS 8
+#endif
+
+#ifndef SEQUENCER_TRACK_THROTTLE
+#    define SEQUENCER_TRACK_THROTTLE 3
+#endif
+
+#ifndef SEQUENCER_PHASE_RELEASE_TIMEOUT
+#    define SEQUENCER_PHASE_RELEASE_TIMEOUT 30
+#endif
+
+/**
+ * Make sure that the items of this enumeration follow the powers of 2, separated by a ternary variant.
+ * Check the implementation of `get_step_duration` for further explanation.
+ */
+typedef enum { SQ_RES_2, SQ_RES_2T, SQ_RES_4, SQ_RES_4T, SQ_RES_8, SQ_RES_8T, SQ_RES_16, SQ_RES_16T, SQ_RES_32, SEQUENCER_RESOLUTIONS } sequencer_resolution_t;
+
+typedef struct {
+    bool                   enabled;
+    uint8_t                steps[SEQUENCER_STEPS];
+    uint16_t               track_notes[SEQUENCER_TRACKS];
+    uint8_t                tempo;  // Is a maximum tempo of 255 reasonable?
+    sequencer_resolution_t resolution;
+} sequencer_config_t;
+
+/**
+ * Because Digital Audio Workstations get overwhelmed when too many MIDI signals are sent concurrently,
+ * We use a "phase" state machine to delay some of the events.
+ */
+typedef enum sequencer_phase_t {
+    SEQUENCER_PHASE_ATTACK,   // t=0ms, send the MIDI note on signal
+    SEQUENCER_PHASE_RELEASE,  // t=SEQUENCER_PHASE_RELEASE_TIMEOUT ms, send the MIDI note off signal
+    SEQUENCER_PHASE_PAUSE     // t=step duration ms, loop
+} sequencer_phase_t;
+
+typedef struct {
+    uint8_t           active_tracks;
+    uint8_t           current_track;
+    uint8_t           current_step;
+    uint16_t          timer;
+    sequencer_phase_t phase;
+} sequencer_state_t;
+
+extern sequencer_config_t sequencer_config;
+
+// We expose the internal state to make the feature more "unit-testable"
+extern sequencer_state_t sequencer_internal_state;
+
+bool is_sequencer_on(void);
+void sequencer_toggle(void);
+void sequencer_on(void);
+void sequencer_off(void);
+
+void sequencer_set_track_notes(const uint16_t track_notes[SEQUENCER_TRACKS]);
+
+bool is_sequencer_track_active(uint8_t track);
+void sequencer_set_track_activation(uint8_t track, bool value);
+void sequencer_toggle_track_activation(uint8_t track);
+void sequencer_toggle_single_active_track(uint8_t track);
+
+#define sequencer_activate_track(track) sequencer_set_track_activation(track, true)
+#define sequencer_deactivate_track(track) sequencer_set_track_activation(track, false)
+
+bool is_sequencer_step_on(uint8_t step);
+bool is_sequencer_step_on_for_track(uint8_t step, uint8_t track);
+void sequencer_set_step(uint8_t step, bool value);
+void sequencer_toggle_step(uint8_t step);
+void sequencer_set_all_steps(bool value);
+
+#define sequencer_set_step_on(step) sequencer_set_step(step, true)
+#define sequencer_set_step_off(step) sequencer_set_step(step, false)
+#define sequencer_set_all_steps_on() sequencer_set_all_steps(true)
+#define sequencer_set_all_steps_off() sequencer_set_all_steps(false)
+
+uint8_t sequencer_get_tempo(void);
+void    sequencer_set_tempo(uint8_t tempo);
+void    sequencer_increase_tempo(void);
+void    sequencer_decrease_tempo(void);
+
+sequencer_resolution_t sequencer_get_resolution(void);
+void                   sequencer_set_resolution(sequencer_resolution_t resolution);
+void                   sequencer_increase_resolution(void);
+void                   sequencer_decrease_resolution(void);
+
+uint8_t sequencer_get_current_step(void);
+
+uint16_t sequencer_get_beat_duration(void);
+uint16_t sequencer_get_step_duration(void);
+
+uint16_t get_beat_duration(uint8_t tempo);
+uint16_t get_step_duration(uint8_t tempo, sequencer_resolution_t resolution);
+
+void matrix_scan_sequencer(void);
diff --git a/quantum/sequencer/tests/midi_mock.c b/quantum/sequencer/tests/midi_mock.c
new file mode 100644
index 0000000000..236e16f9d7
--- /dev/null
+++ b/quantum/sequencer/tests/midi_mock.c
@@ -0,0 +1,26 @@
+/* Copyright 2020 Rodolphe Belouin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "midi_mock.h"
+
+uint16_t last_noteon  = 0;
+uint16_t last_noteoff = 0;
+
+uint16_t midi_compute_note(uint16_t keycode) { return keycode; }
+
+void process_midi_basic_noteon(uint16_t note) { last_noteon = note; }
+
+void process_midi_basic_noteoff(uint16_t note) { last_noteoff = note; }
diff --git a/quantum/sequencer/tests/midi_mock.h b/quantum/sequencer/tests/midi_mock.h
new file mode 100644
index 0000000000..4d8c2eb307
--- /dev/null
+++ b/quantum/sequencer/tests/midi_mock.h
@@ -0,0 +1,26 @@
+/* Copyright 2020 Rodolphe Belouin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+extern uint16_t last_noteon;
+extern uint16_t last_noteoff;
+
+uint16_t midi_compute_note(uint16_t keycode);
+void     process_midi_basic_noteon(uint16_t note);
+void     process_midi_basic_noteoff(uint16_t note);
diff --git a/quantum/sequencer/tests/rules.mk b/quantum/sequencer/tests/rules.mk
new file mode 100644
index 0000000000..76c221cf92
--- /dev/null
+++ b/quantum/sequencer/tests/rules.mk
@@ -0,0 +1,11 @@
+# The letter case of these variables might seem odd. However:
+# - it is consistent with the serial_link example that is used as a reference in the Unit Testing article (https://docs.qmk.fm/#/unit_testing?id=adding-tests-for-new-or-existing-features)
+# - Neither `make test:sequencer` or `make test:SEQUENCER` work when using SCREAMING_SNAKE_CASE
+
+sequencer_DEFS := -DNO_DEBUG -DMIDI_MOCKED
+
+sequencer_SRC := \
+	$(QUANTUM_PATH)/sequencer/tests/midi_mock.c \
+	$(QUANTUM_PATH)/sequencer/tests/sequencer_tests.cpp \
+	$(QUANTUM_PATH)/sequencer/sequencer.c \
+	$(TMK_PATH)/common/test/timer.c
diff --git a/quantum/sequencer/tests/sequencer_tests.cpp b/quantum/sequencer/tests/sequencer_tests.cpp
new file mode 100644
index 0000000000..e81984e5b5
--- /dev/null
+++ b/quantum/sequencer/tests/sequencer_tests.cpp
@@ -0,0 +1,590 @@
+/* Copyright 2020 Rodolphe Belouin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "gtest/gtest.h"
+
+extern "C" {
+#include "sequencer.h"
+#include "midi_mock.h"
+#include "quantum/quantum_keycodes.h"
+}
+
+extern "C" {
+void set_time(uint32_t t);
+void advance_time(uint32_t ms);
+}
+
+class SequencerTest : public ::testing::Test {
+   protected:
+    void SetUp() override {
+        config_copy.enabled = sequencer_config.enabled;
+
+        for (int i = 0; i < SEQUENCER_STEPS; i++) {
+            config_copy.steps[i] = sequencer_config.steps[i];
+        }
+
+        for (int i = 0; i < SEQUENCER_TRACKS; i++) {
+            config_copy.track_notes[i] = sequencer_config.track_notes[i];
+        }
+
+        config_copy.tempo      = sequencer_config.tempo;
+        config_copy.resolution = sequencer_config.resolution;
+
+        state_copy.active_tracks = sequencer_internal_state.active_tracks;
+        state_copy.current_track = sequencer_internal_state.current_track;
+        state_copy.current_step  = sequencer_internal_state.current_step;
+        state_copy.timer         = sequencer_internal_state.timer;
+
+        last_noteon  = 0;
+        last_noteoff = 0;
+
+        set_time(0);
+    }
+
+    void TearDown() override {
+        sequencer_config.enabled = config_copy.enabled;
+
+        for (int i = 0; i < SEQUENCER_STEPS; i++) {
+            sequencer_config.steps[i] = config_copy.steps[i];
+        }
+
+        for (int i = 0; i < SEQUENCER_TRACKS; i++) {
+            sequencer_config.track_notes[i] = config_copy.track_notes[i];
+        }
+
+        sequencer_config.tempo      = config_copy.tempo;
+        sequencer_config.resolution = config_copy.resolution;
+
+        sequencer_internal_state.active_tracks = state_copy.active_tracks;
+        sequencer_internal_state.current_track = state_copy.current_track;
+        sequencer_internal_state.current_step  = state_copy.current_step;
+        sequencer_internal_state.timer         = state_copy.timer;
+    }
+
+    sequencer_config_t config_copy;
+    sequencer_state_t  state_copy;
+};
+
+TEST_F(SequencerTest, TestOffByDefault) { EXPECT_EQ(is_sequencer_on(), false); }
+
+TEST_F(SequencerTest, TestOn) {
+    sequencer_config.enabled = false;
+
+    sequencer_on();
+    EXPECT_EQ(is_sequencer_on(), true);
+
+    // sequencer_on is idempotent
+    sequencer_on();
+    EXPECT_EQ(is_sequencer_on(), true);
+}
+
+TEST_F(SequencerTest, TestOff) {
+    sequencer_config.enabled = true;
+
+    sequencer_off();
+    EXPECT_EQ(is_sequencer_on(), false);
+
+    // sequencer_off is idempotent
+    sequencer_off();
+    EXPECT_EQ(is_sequencer_on(), false);
+}
+
+TEST_F(SequencerTest, TestToggle) {
+    sequencer_config.enabled = false;
+
+    sequencer_toggle();
+    EXPECT_EQ(is_sequencer_on(), true);
+
+    sequencer_toggle();
+    EXPECT_EQ(is_sequencer_on(), false);
+}
+
+TEST_F(SequencerTest, TestNoActiveTrackByDefault) {
+    for (int i = 0; i < SEQUENCER_TRACKS; i++) {
+        EXPECT_EQ(is_sequencer_track_active(i), false);
+    }
+}
+
+TEST_F(SequencerTest, TestGetActiveTracks) {
+    sequencer_internal_state.active_tracks = (1 << 7) + (1 << 6) + (1 << 3) + (1 << 1) + (1 << 0);
+
+    EXPECT_EQ(is_sequencer_track_active(0), true);
+    EXPECT_EQ(is_sequencer_track_active(1), true);
+    EXPECT_EQ(is_sequencer_track_active(2), false);
+    EXPECT_EQ(is_sequencer_track_active(3), true);
+    EXPECT_EQ(is_sequencer_track_active(4), false);
+    EXPECT_EQ(is_sequencer_track_active(5), false);
+    EXPECT_EQ(is_sequencer_track_active(6), true);
+    EXPECT_EQ(is_sequencer_track_active(7), true);
+}
+
+TEST_F(SequencerTest, TestGetActiveTracksOutOfBound) {
+    sequencer_set_track_activation(-1, true);
+    sequencer_set_track_activation(8, true);
+
+    EXPECT_EQ(is_sequencer_track_active(-1), false);
+    EXPECT_EQ(is_sequencer_track_active(8), false);
+}
+
+TEST_F(SequencerTest, TestToggleTrackActivation) {
+    sequencer_internal_state.active_tracks = (1 << 7) + (1 << 6) + (1 << 3) + (1 << 1) + (1 << 0);
+
+    sequencer_toggle_track_activation(6);
+
+    EXPECT_EQ(is_sequencer_track_active(0), true);
+    EXPECT_EQ(is_sequencer_track_active(1), true);
+    EXPECT_EQ(is_sequencer_track_active(2), false);
+    EXPECT_EQ(is_sequencer_track_active(3), true);
+    EXPECT_EQ(is_sequencer_track_active(4), false);
+    EXPECT_EQ(is_sequencer_track_active(5), false);
+    EXPECT_EQ(is_sequencer_track_active(6), false);
+    EXPECT_EQ(is_sequencer_track_active(7), true);
+}
+
+TEST_F(SequencerTest, TestToggleSingleTrackActivation) {
+    sequencer_internal_state.active_tracks = (1 << 7) + (1 << 6) + (1 << 3) + (1 << 1) + (1 << 0);
+
+    sequencer_toggle_single_active_track(2);
+
+    EXPECT_EQ(is_sequencer_track_active(0), false);
+    EXPECT_EQ(is_sequencer_track_active(1), false);
+    EXPECT_EQ(is_sequencer_track_active(2), true);
+    EXPECT_EQ(is_sequencer_track_active(3), false);
+    EXPECT_EQ(is_sequencer_track_active(4), false);
+    EXPECT_EQ(is_sequencer_track_active(5), false);
+    EXPECT_EQ(is_sequencer_track_active(6), false);
+    EXPECT_EQ(is_sequencer_track_active(7), false);
+}
+
+TEST_F(SequencerTest, TestStepOffByDefault) {
+    for (int i = 0; i < SEQUENCER_STEPS; i++) {
+        EXPECT_EQ(is_sequencer_step_on(i), false);
+    }
+}
+
+TEST_F(SequencerTest, TestIsStepOffWithNoActiveTracks) {
+    sequencer_config.steps[3] = 0xFF;
+    EXPECT_EQ(is_sequencer_step_on(3), false);
+}
+
+TEST_F(SequencerTest, TestIsStepOffWithGivenActiveTracks) {
+    sequencer_set_track_activation(2, true);
+    sequencer_set_track_activation(3, true);
+
+    sequencer_config.steps[3] = (1 << 0) + (1 << 1);
+
+    // No active tracks have the step enabled, so it is off
+    EXPECT_EQ(is_sequencer_step_on(3), false);
+}
+
+TEST_F(SequencerTest, TestIsStepOnWithGivenActiveTracks) {
+    sequencer_set_track_activation(2, true);
+    sequencer_set_track_activation(3, true);
+
+    sequencer_config.steps[3] = (1 << 2);
+
+    // Track 2 has the step enabled, so it is on
+    EXPECT_EQ(is_sequencer_step_on(3), true);
+}
+
+TEST_F(SequencerTest, TestIsStepOffForGivenTrack) {
+    sequencer_config.steps[3] = 0x00;
+    EXPECT_EQ(is_sequencer_step_on_for_track(3, 5), false);
+}
+
+TEST_F(SequencerTest, TestIsStepOnForGivenTrack) {
+    sequencer_config.steps[3] = (1 << 5);
+    EXPECT_EQ(is_sequencer_step_on_for_track(3, 5), true);
+}
+
+TEST_F(SequencerTest, TestSetStepOn) {
+    sequencer_internal_state.active_tracks = (1 << 6) + (1 << 3) + (1 << 2);
+    sequencer_config.steps[2]              = (1 << 5) + (1 << 2);
+
+    sequencer_set_step(2, true);
+
+    EXPECT_EQ(sequencer_config.steps[2], (1 << 6) + (1 << 5) + (1 << 3) + (1 << 2));
+}
+
+TEST_F(SequencerTest, TestSetStepOff) {
+    sequencer_internal_state.active_tracks = (1 << 6) + (1 << 3) + (1 << 2);
+    sequencer_config.steps[2]              = (1 << 5) + (1 << 2);
+
+    sequencer_set_step(2, false);
+
+    EXPECT_EQ(sequencer_config.steps[2], (1 << 5));
+}
+
+TEST_F(SequencerTest, TestToggleStepOff) {
+    sequencer_internal_state.active_tracks = (1 << 6) + (1 << 3) + (1 << 2);
+    sequencer_config.steps[2]              = (1 << 5) + (1 << 2);
+
+    sequencer_toggle_step(2);
+
+    EXPECT_EQ(sequencer_config.steps[2], (1 << 5));
+}
+
+TEST_F(SequencerTest, TestToggleStepOn) {
+    sequencer_internal_state.active_tracks = (1 << 6) + (1 << 3) + (1 << 2);
+    sequencer_config.steps[2]              = 0;
+
+    sequencer_toggle_step(2);
+
+    EXPECT_EQ(sequencer_config.steps[2], (1 << 6) + (1 << 3) + (1 << 2));
+}
+
+TEST_F(SequencerTest, TestSetAllStepsOn) {
+    sequencer_internal_state.active_tracks = (1 << 6) + (1 << 3) + (1 << 2);
+    sequencer_config.steps[2]              = (1 << 7) + (1 << 6);
+    sequencer_config.steps[4]              = (1 << 3) + (1 << 1);
+
+    sequencer_set_all_steps(true);
+
+    EXPECT_EQ(sequencer_config.steps[2], (1 << 7) + (1 << 6) + (1 << 3) + (1 << 2));
+    EXPECT_EQ(sequencer_config.steps[4], (1 << 6) + (1 << 3) + (1 << 2) + (1 << 1));
+}
+
+TEST_F(SequencerTest, TestSetAllStepsOff) {
+    sequencer_internal_state.active_tracks = (1 << 6) + (1 << 3) + (1 << 2);
+    sequencer_config.steps[2]              = (1 << 7) + (1 << 6);
+    sequencer_config.steps[4]              = (1 << 3) + (1 << 1);
+
+    sequencer_set_all_steps(false);
+
+    EXPECT_EQ(sequencer_config.steps[2], (1 << 7));
+    EXPECT_EQ(sequencer_config.steps[4], (1 << 1));
+}
+
+TEST_F(SequencerTest, TestSetTempoZero) {
+    sequencer_config.tempo = 123;
+
+    sequencer_set_tempo(0);
+
+    EXPECT_EQ(sequencer_config.tempo, 123);
+}
+
+TEST_F(SequencerTest, TestIncreaseTempoMax) {
+    sequencer_config.tempo = UINT8_MAX;
+
+    sequencer_increase_tempo();
+
+    EXPECT_EQ(sequencer_config.tempo, UINT8_MAX);
+}
+
+TEST_F(SequencerTest, TestSetResolutionLowerBound) {
+    sequencer_config.resolution = SQ_RES_4;
+
+    sequencer_set_resolution((sequencer_resolution_t)-1);
+
+    EXPECT_EQ(sequencer_config.resolution, SQ_RES_4);
+}
+
+TEST_F(SequencerTest, TestSetResolutionUpperBound) {
+    sequencer_config.resolution = SQ_RES_4;
+
+    sequencer_set_resolution(SEQUENCER_RESOLUTIONS);
+
+    EXPECT_EQ(sequencer_config.resolution, SQ_RES_4);
+}
+
+TEST_F(SequencerTest, TestGetBeatDuration) {
+    EXPECT_EQ(get_beat_duration(60), 1000);
+    EXPECT_EQ(get_beat_duration(120), 500);
+    EXPECT_EQ(get_beat_duration(240), 250);
+    EXPECT_EQ(get_beat_duration(0), 1000);
+}
+
+TEST_F(SequencerTest, TestGetStepDuration60) {
+    /**
+     * Resolution cheatsheet:
+     * 1/2  => 2 steps per 4 beats
+     * 1/2T => 3 steps per 4 beats
+     * 1/4  => 4 steps per 4 beats
+     * 1/4T => 6 steps per 4 beats
+     * 1/8  => 8 steps per 4 beats
+     * 1/8T => 12 steps per 4 beats
+     * 1/16 => 16 steps per 4 beats
+     * 1/16T => 24 steps per 4 beats
+     * 1/32 => 32 steps per 4 beats
+     *
+     * The number of steps for binary resolutions follows the powers of 2.
+     * The ternary variants are simply 1.5x faster.
+     */
+    EXPECT_EQ(get_step_duration(60, SQ_RES_2), 2000);
+    EXPECT_EQ(get_step_duration(60, SQ_RES_4), 1000);
+    EXPECT_EQ(get_step_duration(60, SQ_RES_8), 500);
+    EXPECT_EQ(get_step_duration(60, SQ_RES_16), 250);
+    EXPECT_EQ(get_step_duration(60, SQ_RES_32), 125);
+
+    EXPECT_EQ(get_step_duration(60, SQ_RES_2T), 1333);
+    EXPECT_EQ(get_step_duration(60, SQ_RES_4T), 666);
+    EXPECT_EQ(get_step_duration(60, SQ_RES_8T), 333);
+    EXPECT_EQ(get_step_duration(60, SQ_RES_16T), 166);
+}
+
+TEST_F(SequencerTest, TestGetStepDuration120) {
+    /**
+     * Resolution cheatsheet:
+     * 1/2  => 2 steps per 4 beats
+     * 1/2T => 3 steps per 4 beats
+     * 1/4  => 4 steps per 4 beats
+     * 1/4T => 6 steps per 4 beats
+     * 1/8  => 8 steps per 4 beats
+     * 1/8T => 12 steps per 4 beats
+     * 1/16 => 16 steps per 4 beats
+     * 1/16T => 24 steps per 4 beats
+     * 1/32 => 32 steps per 4 beats
+     *
+     * The number of steps for binary resolutions follows the powers of 2.
+     * The ternary variants are simply 1.5x faster.
+     */
+    EXPECT_EQ(get_step_duration(30, SQ_RES_2), 4000);
+    EXPECT_EQ(get_step_duration(30, SQ_RES_4), 2000);
+    EXPECT_EQ(get_step_duration(30, SQ_RES_8), 1000);
+    EXPECT_EQ(get_step_duration(30, SQ_RES_16), 500);
+    EXPECT_EQ(get_step_duration(30, SQ_RES_32), 250);
+
+    EXPECT_EQ(get_step_duration(30, SQ_RES_2T), 2666);
+    EXPECT_EQ(get_step_duration(30, SQ_RES_4T), 1333);
+    EXPECT_EQ(get_step_duration(30, SQ_RES_8T), 666);
+    EXPECT_EQ(get_step_duration(30, SQ_RES_16T), 333);
+}
+
+void setUpMatrixScanSequencerTest(void) {
+    sequencer_config.enabled    = true;
+    sequencer_config.tempo      = 120;
+    sequencer_config.resolution = SQ_RES_16;
+
+    // Configure the notes for each track
+    sequencer_config.track_notes[0] = MI_C;
+    sequencer_config.track_notes[1] = MI_D;
+    sequencer_config.track_notes[2] = MI_E;
+    sequencer_config.track_notes[3] = MI_F;
+    sequencer_config.track_notes[4] = MI_G;
+    sequencer_config.track_notes[5] = MI_A;
+    sequencer_config.track_notes[6] = MI_B;
+    sequencer_config.track_notes[7] = MI_C;
+
+    // Turn on some steps
+    sequencer_config.steps[0] = (1 << 0);
+    sequencer_config.steps[2] = (1 << 1) + (1 << 0);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldAttackFirstTrackOfFirstStep) {
+    setUpMatrixScanSequencerTest();
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(last_noteon, MI_C);
+    EXPECT_EQ(last_noteoff, 0);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldAttackSecondTrackAfterFirstTrackOfFirstStep) {
+    setUpMatrixScanSequencerTest();
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(sequencer_internal_state.current_step, 0);
+    EXPECT_EQ(sequencer_internal_state.current_track, 1);
+    EXPECT_EQ(sequencer_internal_state.phase, SEQUENCER_PHASE_ATTACK);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldNotAttackInactiveTrackFirstStep) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = 1;
+
+    // Wait some time after the first track has been attacked
+    advance_time(SEQUENCER_TRACK_THROTTLE);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(last_noteon, 0);
+    EXPECT_EQ(last_noteoff, 0);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldAttackThirdTrackAfterSecondTrackOfFirstStep) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = 1;
+
+    // Wait some time after the second track has been attacked
+    advance_time(2 * SEQUENCER_TRACK_THROTTLE);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(sequencer_internal_state.current_step, 0);
+    EXPECT_EQ(sequencer_internal_state.current_track, 2);
+    EXPECT_EQ(sequencer_internal_state.phase, SEQUENCER_PHASE_ATTACK);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldEnterReleasePhaseAfterLastTrackHasBeenProcessedFirstStep) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = SEQUENCER_TRACKS - 1;
+
+    // Wait until all notes have been attacked
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(last_noteon, 0);
+    EXPECT_EQ(last_noteoff, 0);
+    EXPECT_EQ(sequencer_internal_state.current_step, 0);
+    EXPECT_EQ(sequencer_internal_state.current_track, SEQUENCER_TRACKS - 1);
+    EXPECT_EQ(sequencer_internal_state.phase, SEQUENCER_PHASE_RELEASE);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldReleaseBackwards) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = SEQUENCER_TRACKS - 1;
+    sequencer_internal_state.phase         = SEQUENCER_PHASE_RELEASE;
+
+    // Wait until all notes have been attacked
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the release timeout
+    advance_time(SEQUENCER_PHASE_RELEASE_TIMEOUT);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(sequencer_internal_state.current_step, 0);
+    EXPECT_EQ(sequencer_internal_state.current_track, SEQUENCER_TRACKS - 2);
+    EXPECT_EQ(sequencer_internal_state.phase, SEQUENCER_PHASE_RELEASE);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldNotReleaseInactiveTrackFirstStep) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = SEQUENCER_TRACKS - 1;
+    sequencer_internal_state.phase         = SEQUENCER_PHASE_RELEASE;
+
+    // Wait until all notes have been attacked
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the release timeout
+    advance_time(SEQUENCER_PHASE_RELEASE_TIMEOUT);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(last_noteon, 0);
+    EXPECT_EQ(last_noteoff, 0);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldReleaseFirstTrackFirstStep) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = 0;
+    sequencer_internal_state.phase         = SEQUENCER_PHASE_RELEASE;
+
+    // Wait until all notes have been attacked
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the release timeout
+    advance_time(SEQUENCER_PHASE_RELEASE_TIMEOUT);
+    // + all the other notes have been released
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(last_noteon, 0);
+    EXPECT_EQ(last_noteoff, MI_C);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldEnterPausePhaseAfterRelease) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = 0;
+    sequencer_internal_state.phase         = SEQUENCER_PHASE_RELEASE;
+
+    // Wait until all notes have been attacked
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the release timeout
+    advance_time(SEQUENCER_PHASE_RELEASE_TIMEOUT);
+    // + all the other notes have been released
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(sequencer_internal_state.current_step, 0);
+    EXPECT_EQ(sequencer_internal_state.current_track, 0);
+    EXPECT_EQ(sequencer_internal_state.phase, SEQUENCER_PHASE_PAUSE);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldProcessFirstTrackOfSecondStepAfterPause) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 0;
+    sequencer_internal_state.current_track = 0;
+    sequencer_internal_state.phase         = SEQUENCER_PHASE_PAUSE;
+
+    // Wait until all notes have been attacked
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the release timeout
+    advance_time(SEQUENCER_PHASE_RELEASE_TIMEOUT);
+    // + all the other notes have been released
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the step duration (one 16th at tempo=120 lasts 125ms)
+    advance_time(125);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(sequencer_internal_state.current_step, 1);
+    EXPECT_EQ(sequencer_internal_state.current_track, 1);
+    EXPECT_EQ(sequencer_internal_state.phase, SEQUENCER_PHASE_ATTACK);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldProcessSecondTrackTooEarly) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 2;
+    sequencer_internal_state.current_track = 1;
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(last_noteon, 0);
+    EXPECT_EQ(last_noteoff, 0);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldProcessSecondTrackOnTime) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = 2;
+    sequencer_internal_state.current_track = 1;
+
+    // Wait until first track has been attacked
+    advance_time(SEQUENCER_TRACK_THROTTLE);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(last_noteon, MI_D);
+    EXPECT_EQ(last_noteoff, 0);
+}
+
+TEST_F(SequencerTest, TestMatrixScanSequencerShouldLoopOnceSequenceIsOver) {
+    setUpMatrixScanSequencerTest();
+
+    sequencer_internal_state.current_step  = SEQUENCER_STEPS - 1;
+    sequencer_internal_state.current_track = 0;
+    sequencer_internal_state.phase         = SEQUENCER_PHASE_PAUSE;
+
+    // Wait until all notes have been attacked
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the release timeout
+    advance_time(SEQUENCER_PHASE_RELEASE_TIMEOUT);
+    // + all the other notes have been released
+    advance_time((SEQUENCER_TRACKS - 1) * SEQUENCER_TRACK_THROTTLE);
+    // + the step duration (one 16th at tempo=120 lasts 125ms)
+    advance_time(125);
+
+    matrix_scan_sequencer();
+    EXPECT_EQ(sequencer_internal_state.current_step, 0);
+    EXPECT_EQ(sequencer_internal_state.current_track, 1);
+    EXPECT_EQ(sequencer_internal_state.phase, SEQUENCER_PHASE_ATTACK);
+}
diff --git a/quantum/sequencer/tests/testlist.mk b/quantum/sequencer/tests/testlist.mk
new file mode 100644
index 0000000000..bb38991109
--- /dev/null
+++ b/quantum/sequencer/tests/testlist.mk
@@ -0,0 +1 @@
+TEST_LIST += sequencer