[Keyboard] Convert Corne Keyboard to Split Common (#6001)

* [Keyboard] Convert Corne Keyboard to Split Common

* Add VIA Support

* Makes sure that ol(e)d and new OLED implementation can't coexist

* Add licensing header to files

* Add changes based on feedback from foostan

* Fixes

33 files changed, 2309 insertions, 106 deletions

diff --git a/keyboards/crkbd/rev1/common/common.c b/keyboards/crkbd/rev1/common/common.c
new file mode 100644
index 0000000000..5ea7347de8
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/common.c
@@ -0,0 +1,21 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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 "common.h"
+
+uint8_t is_master;
diff --git a/keyboards/crkbd/rev1/common/common.h b/keyboards/crkbd/rev1/common/common.h
new file mode 100644
index 0000000000..af1795f480
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/common.h
@@ -0,0 +1,24 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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 "rev1.h"
+
+#define has_usb() is_keyboard_master()
+extern uint8_t is_master;
diff --git a/keyboards/crkbd/rev1/common/config.h b/keyboards/crkbd/rev1/common/config.h
new file mode 100644
index 0000000000..12f5f75766
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/config.h
@@ -0,0 +1,30 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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
+
+#define PRODUCT         Corne Keyboard Rev.1 (Split Common)
+
+#define USE_SERIAL
+#define SOFT_SERIAL_PIN D2
+
+#ifdef RGB_MATRIX_ENABLE
+#    define RGB_MATRIX_SPLIT { 27, 27 }
+#endif
+
+#define DIODE_DIRECTION COL2ROW
diff --git a/keyboards/crkbd/rev1/common/keymaps/via/config.h b/keyboards/crkbd/rev1/common/keymaps/via/config.h
new file mode 100644
index 0000000000..aa2d45e56d
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/keymaps/via/config.h
@@ -0,0 +1,46 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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
+
+//#define USE_MATRIX_I2C
+#ifdef KEYBOARD_crkbd_rev1_legacy
+#    undef USE_I2C
+#    define USE_SERIAL
+#endif
+
+/* Select hand configuration */
+
+#define MASTER_LEFT
+// #define MASTER_RIGHT
+// #define EE_HANDS
+
+#define USE_SERIAL_PD2
+
+
+#undef RGBLED_NUM
+#define RGBLIGHT_ANIMATIONS
+#define RGBLED_NUM 27
+#define RGBLIGHT_LIMIT_VAL 120
+#define RGBLIGHT_HUE_STEP 10
+#define RGBLIGHT_SAT_STEP 17
+#define RGBLIGHT_VAL_STEP 17
+
+#define OLED_FONT_H "keyboards/crkbd/lib/glcdfont.c"
diff --git a/keyboards/crkbd/rev1/common/keymaps/via/keymap.c b/keyboards/crkbd/rev1/common/keymaps/via/keymap.c
new file mode 100644
index 0000000000..a3b2e52ce5
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/keymaps/via/keymap.c
@@ -0,0 +1,193 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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 QMK_KEYBOARD_H
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+  [0] = LAYOUT_split_3x6_3( \
+  //,-----------------------------------------------------.                    ,-----------------------------------------------------.
+       KC_TAB,    KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,                         KC_Y,    KC_U,    KC_I,    KC_O,   KC_P,  KC_BSPC,
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      KC_LCTL,    KC_A,    KC_S,    KC_D,    KC_F,    KC_G,                         KC_H,    KC_J,    KC_K,    KC_L, KC_SCLN, KC_QUOT,
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      KC_LSFT,    KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,                         KC_N,    KC_M, KC_COMM,  KC_DOT, KC_SLSH,  KC_ESC,
+  //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
+                                          KC_LGUI, FN_MO13,  KC_SPC,     KC_ENT, FN_MO23, KC_RALT
+                                      //`--------------------------'  `--------------------------'
+
+  ),
+
+  [1] = LAYOUT_split_3x6_3( \
+  //,-----------------------------------------------------.                    ,-----------------------------------------------------.
+       KC_TAB,    KC_1,    KC_2,    KC_3,    KC_4,    KC_5,                         KC_6,    KC_7,    KC_8,    KC_9,    KC_0, KC_BSPC,
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      KC_LCTL, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      KC_LEFT, KC_DOWN,   KC_UP,KC_RIGHT, XXXXXXX, XXXXXXX,
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      KC_LSFT, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
+  //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
+                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT\
+                                      //`--------------------------'  `--------------------------'
+  ),
+
+  [2] = LAYOUT_split_3x6_3( \
+  //,-----------------------------------------------------.                    ,-----------------------------------------------------.
+       KC_TAB, KC_EXLM,   KC_AT, KC_HASH,  KC_DLR, KC_PERC,                      KC_CIRC, KC_AMPR, KC_ASTR, KC_LPRN, KC_RPRN, KC_BSPC,
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      KC_LCTL, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      KC_MINS,  KC_EQL, KC_LBRC, KC_RBRC, KC_BSLS,  KC_GRV,
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      KC_LSFT, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      KC_UNDS, KC_PLUS, KC_LCBR, KC_RCBR, KC_PIPE, KC_TILD,
+  //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
+                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT
+                                      //`--------------------------'  `--------------------------'
+  ),
+
+  [3] = LAYOUT_split_3x6_3( \
+  //,-----------------------------------------------------.                    ,-----------------------------------------------------.
+        RESET, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,\
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      RGB_TOG, RGB_HUI, RGB_SAI, RGB_VAI, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,\
+  //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
+      RGB_MOD, RGB_HUD, RGB_SAD, RGB_VAD, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,\
+  //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
+                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT\
+                                      //`--------------------------'  `--------------------------'
+  )
+};
+
+#ifdef OLED_DRIVER_ENABLE
+oled_rotation_t oled_init_user(oled_rotation_t rotation) {
+  if (!is_master) {
+    return OLED_ROTATION_180;  // flips the display 180 degrees if offhand
+  }
+  return rotation;
+}
+
+#define L_BASE 0
+#define L_LOWER 2
+#define L_RAISE 4
+#define L_ADJUST 8
+
+void oled_render_layer_state(void) {
+    oled_write_P("Layer: ", false);
+    switch (layer_state) {
+        case L_BASE:
+            oled_write_ln_P("Default", false);
+            break;
+        case L_LOWER:
+            oled_write_ln_P("Lower", false);
+            break;
+        case L_RAISE:
+            oled_write_ln_P("Raise", false);
+            break;
+        case L_ADJUST:
+        case L_ADJUST|L_LOWER:
+        case L_ADJUST|L_RAISE:
+        case L_ADJUST|L_LOWER|L_RAISE:
+            oled_write_ln_P("Adjust", false);
+            break;
+    }
+}
+
+
+char keylog_str[24] = {};
+char keylogs_str[21] = {};
+int keylogs_str_idx = 0;
+
+const char code_to_name[60] = {
+    ' ', ' ', ' ', ' ', 'a', 'b', 'c', 'd', 'e', 'f',
+    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
+    'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
+    '1', '2', '3', '4', '5', '6', '7', '8', '9', '0',
+    'R', 'E', 'B', 'T', '_', '-', '=', '[', ']', '\\',
+    '#', ';', '\'', '`', ',', '.', '/', ' ', ' ', ' '};
+
+void set_keylog(uint16_t keycode, keyrecord_t *record) {
+  char name = ' ';
+    if ((keycode >= QK_MOD_TAP && keycode <= QK_MOD_TAP_MAX) ||
+        (keycode >= QK_LAYER_TAP && keycode <= QK_LAYER_TAP_MAX)) { keycode = keycode & 0xFF; }
+  if (keycode < 60) {
+    name = code_to_name[keycode];
+  }
+
+  // update keylog
+  snprintf(keylog_str, sizeof(keylog_str), "%dx%d, k%2d : %c",
+           record->event.key.row, record->event.key.col,
+           keycode, name);
+
+  // update keylogs
+  if (keylogs_str_idx == sizeof(keylogs_str) - 1) {
+    keylogs_str_idx = 0;
+    for (int i = 0; i < sizeof(keylogs_str) - 1; i++) {
+      keylogs_str[i] = ' ';
+    }
+  }
+
+  keylogs_str[keylogs_str_idx] = name;
+  keylogs_str_idx++;
+}
+
+void oled_render_keylog(void) {
+    oled_write(keylog_str, false);
+}
+void oled_render_keylogs(void) {
+    oled_write(keylogs_str, false);
+}
+
+void render_bootmagic_status(bool status) {
+    /* Show Ctrl-Gui Swap options */
+    static const char PROGMEM logo[][2][3] = {
+        {{0x97, 0x98, 0}, {0xb7, 0xb8, 0}},
+        {{0x95, 0x96, 0}, {0xb5, 0xb6, 0}},
+    };
+    if (status) {
+        oled_write_ln_P(logo[0][0], false);
+        oled_write_ln_P(logo[0][1], false);
+    } else {
+        oled_write_ln_P(logo[1][0], false);
+        oled_write_ln_P(logo[1][1], false);
+    }
+}
+
+void oled_render_logo(void) {
+    static const char PROGMEM crkbd_logo[] = {
+        0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94,
+        0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4,
+        0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4,
+        0};
+    oled_write_P(crkbd_logo, false);
+}
+
+void oled_task_user(void) {
+    if (is_master) {
+        oled_render_layer_state();
+        oled_render_keylog();
+        // oled_render_keylogs();
+        // oled_renger_bootmagic_icon(keymap_config.swap_lalt_lgui);
+    } else {
+        oled_render_logo();
+    }
+}
+
+bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+  if (record->event.pressed) {
+    set_keylog(keycode, record);
+    // set_timelog();
+  }
+  return true;
+}
+#endif // OLED_DRIVER_ENABLE
diff --git a/keyboards/crkbd/rev1/common/keymaps/via/rules.mk b/keyboards/crkbd/rev1/common/keymaps/via/rules.mk
new file mode 100644
index 0000000000..93b2afed44
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/keymaps/via/rules.mk
@@ -0,0 +1,5 @@
+MOUSEKEY_ENABLE     = no     # Mouse keys
+RGBLIGHT_ENABLE     = yes    # Enable WS2812 RGB underlight.
+VIA_ENABLE          = yes         # Enable VIA
+OLED_DRIVER_ENABLE  = yes
+LTO_ENABLE          = yes
diff --git a/keyboards/crkbd/rev1/common/rules.mk b/keyboards/crkbd/rev1/common/rules.mk
new file mode 100644
index 0000000000..0b8106e3f2
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/rules.mk
@@ -0,0 +1,2 @@
+SPLIT_KEYBOARD = yes
+SPLIT_TRANSPORT = mirror    # for when Split Mirroring drops, it will maintain mirroring functionality
diff --git a/keyboards/crkbd/rev1/common/ssd1306.c b/keyboards/crkbd/rev1/common/ssd1306.c
new file mode 100644
index 0000000000..4a889da673
--- /dev/null
+++ b/keyboards/crkbd/rev1/common/ssd1306.c
@@ -0,0 +1,360 @@
+#ifdef SSD1306OLED
+
+#include "ssd1306.h"
+#include "i2c_master.h"
+#include <string.h>
+#include "print.h"
+#ifdef ADAFRUIT_BLE_ENABLE
+#include "adafruit_ble.h"
+#endif
+#ifdef PROTOCOL_LUFA
+#include "lufa.h"
+#endif
+#include "sendchar.h"
+#include "timer.h"
+
+struct CharacterMatrix display;
+
+extern const unsigned char font[] PROGMEM;
+
+#ifndef OLED_BLANK_CHAR
+#define OLED_BLANK_CHAR ' '
+#endif
+
+#ifndef OLED_BITS_FILTER
+#define OLED_BITS_FILTER
+#endif
+
+// Set this to 1 to help diagnose early startup problems
+// when testing power-on with ble.  Turn it off otherwise,
+// as the latency of printing most of the debug info messes
+// with the matrix scan, causing keys to drop.
+#define DEBUG_TO_SCREEN 0
+
+//static uint16_t last_battery_update;
+//static uint32_t vbat;
+//#define BatteryUpdateInterval 10000 /* milliseconds */
+
+// 'last_flush' is declared as uint16_t,
+// so this must be less than 65535
+#ifndef ScreenOffInterval
+#define ScreenOffInterval 60000 /* milliseconds */
+#endif
+
+#if DEBUG_TO_SCREEN
+static uint8_t displaying;
+#endif
+static uint16_t last_flush;
+
+static bool force_dirty = true;
+
+// Write command sequence.
+// Returns true on success.
+static inline bool _send_cmd1(uint8_t cmd) {
+  bool res = false;
+
+  if (i2c_start(SSD1306_ADDRESS, 100)) {
+    xprintf("failed to start write to %d\n", SSD1306_ADDRESS);
+    goto done;
+  }
+
+  if (i2c_write(0x0 /* command byte follows */, 100)) {
+    print("failed to write control byte\n");
+
+    goto done;
+  }
+
+  if (i2c_write(cmd, 100)) {
+    xprintf("failed to write command %d\n", cmd);
+    goto done;
+  }
+  res = true;
+done:
+  i2c_stop();
+  return res;
+}
+
+#define send_cmd1(c) if (!_send_cmd1(c)) {goto done;}
+#define send_cmds(c) if (!_send_cmds(c,sizeof(c))) {goto done;}
+#define cmd1(X) X
+#define cmd2(X,Y) X,Y
+#define cmd3(X,Y,Z) X,Y,Z
+
+static bool _send_cmds(const uint8_t* p,uint8_t sz) {
+  for(uint8_t i=sz;i;i--) {
+    send_cmd1( pgm_read_byte(p++) );
+  }
+  return true;
+done:
+  return false;
+}
+
+#define SEND_CMDS(...) {static const uint8_t _cmds[] PROGMEM = { __VA_ARGS__,0 };send_cmds(_cmds);}
+
+static void clear_display(void) {
+  matrix_clear(&display);
+
+  // Clear all of the display bits (there can be random noise
+  // in the RAM on startup)
+  SEND_CMDS(
+    cmd3(PageAddr, 0, (DisplayHeight / 8) - 1),
+    cmd3(ColumnAddr, 0, DisplayWidth - 1)
+  );
+
+  if (i2c_start(SSD1306_ADDRESS, 100)) {
+    goto done;
+  }
+  if (i2c_write(0x40, 100)) {
+    // Data mode
+    goto done;
+  }
+  for (uint8_t row = MatrixRows;row; row--) {
+    for (uint8_t col = DisplayWidth; col; col--) {
+      i2c_write(0, 100);
+    }
+  }
+
+  display.dirty = false;
+
+done:
+  i2c_stop();
+}
+
+#if DEBUG_TO_SCREEN
+#undef sendchar
+static int8_t capture_sendchar(uint8_t c) {
+  sendchar(c);
+  iota_gfx_write_char(c);
+
+  if (!displaying) {
+    iota_gfx_flush();
+  }
+  return 0;
+}
+#endif
+
+bool iota_gfx_init(bool rotate) {
+  bool success = false;
+
+  i2c_init();
+  SEND_CMDS(
+    cmd1(DisplayOff),
+    cmd2(SetDisplayClockDiv, 0x80),
+    cmd2(SetMultiPlex, DisplayHeight - 1),
+    cmd2(SetDisplayOffset, 0),
+    cmd1(SetStartLine | 0x0),
+    cmd2(SetChargePump, 0x14 /* Enable */),
+    cmd2(SetMemoryMode, 0 /* horizontal addressing */)
+  );
+
+  if(rotate){
+    // the following Flip the display orientation 180 degrees
+  SEND_CMDS(
+    cmd1(SegRemap),
+    cmd1(ComScanInc)
+  );
+  }else{
+    // Flips the display orientation 0 degrees
+  SEND_CMDS(
+      cmd1(SegRemap | 0x1),
+      cmd1(ComScanDec)
+    );
+  }
+
+  SEND_CMDS(
+#ifdef SSD1306_128X64
+	cmd2(SetComPins, 0x12),
+#else
+	cmd2(SetComPins, 0x2),
+#endif
+    cmd2(SetContrast, 0x8f),
+    cmd2(SetPreCharge, 0xf1),
+    cmd2(SetVComDetect, 0x40),
+    cmd1(DisplayAllOnResume),
+    cmd1(NormalDisplay),
+    cmd1(DeActivateScroll),
+    cmd1(DisplayOn),
+
+    cmd2(SetContrast, 0) // Dim
+  );
+
+  clear_display();
+
+  success = true;
+
+  iota_gfx_flush();
+
+#if DEBUG_TO_SCREEN
+  print_set_sendchar(capture_sendchar);
+#endif
+
+done:
+  return success;
+}
+
+bool iota_gfx_off(void) {
+  bool success = false;
+
+  send_cmd1(DisplayOff);
+  success = true;
+
+done:
+  return success;
+}
+
+bool iota_gfx_on(void) {
+  bool success = false;
+
+  send_cmd1(DisplayOn);
+  success = true;
+
+done:
+  return success;
+}
+
+void matrix_write_char_inner(struct CharacterMatrix *matrix, uint8_t c) {
+  *matrix->cursor = c;
+  ++matrix->cursor;
+
+  if (matrix->cursor - &matrix->display[0][0] == sizeof(matrix->display)) {
+    // We went off the end; scroll the display upwards by one line
+    memmove(&matrix->display[0], &matrix->display[1],
+            MatrixCols * (MatrixRows - 1));
+    matrix->cursor = &matrix->display[MatrixRows - 1][0];
+    memset(matrix->cursor, OLED_BLANK_CHAR, MatrixCols);
+  }
+}
+
+void matrix_write_char(struct CharacterMatrix *matrix, uint8_t c) {
+  matrix->dirty = true;
+
+  if (c == '\n') {
+    // Clear to end of line from the cursor and then move to the
+    // start of the next line
+    uint8_t cursor_col = (matrix->cursor - &matrix->display[0][0]) % MatrixCols;
+
+    while (cursor_col++ < MatrixCols) {
+      matrix_write_char_inner(matrix, OLED_BLANK_CHAR);
+    }
+    return;
+  }
+
+  matrix_write_char_inner(matrix, c);
+}
+
+void iota_gfx_write_char(uint8_t c) {
+  matrix_write_char(&display, c);
+}
+
+void matrix_write(struct CharacterMatrix *matrix, const char *data) {
+  while (*data) {
+    matrix_write_char(matrix, *data);
+    ++data;
+  }
+}
+
+void matrix_write_ln(struct CharacterMatrix *matrix, const char *data) {
+  matrix_write(matrix, data);
+  matrix_write(matrix, "\n");
+}
+
+void iota_gfx_write(const char *data) {
+  matrix_write(&display, data);
+}
+
+void matrix_write_P(struct CharacterMatrix *matrix, const char *data) {
+  while (true) {
+    uint8_t c = pgm_read_byte(data);
+    if (c == 0) {
+      return;
+    }
+    matrix_write_char(matrix, c);
+    ++data;
+  }
+}
+
+void iota_gfx_write_P(const char *data) {
+  matrix_write_P(&display, data);
+}
+
+void matrix_clear(struct CharacterMatrix *matrix) {
+  memset(matrix->display, OLED_BLANK_CHAR, sizeof(matrix->display));
+  matrix->cursor = &matrix->display[0][0];
+  matrix->dirty = true;
+}
+
+void iota_gfx_clear_screen(void) {
+  matrix_clear(&display);
+}
+
+void matrix_render(struct CharacterMatrix *matrix) {
+  last_flush = timer_read();
+  iota_gfx_on();
+#if DEBUG_TO_SCREEN
+  ++displaying;
+#endif
+
+  // Move to the home position
+  SEND_CMDS(
+    cmd3(PageAddr, 0, MatrixRows - 1),
+    cmd3(ColumnAddr, 0, (MatrixCols * FontWidth) - 1)
+  );
+
+  if (i2c_write(SSD1306_ADDRESS, 100)) {
+    goto done;
+  }
+  if (i2c_write(0x40, 100)) {
+    // Data mode
+    goto done;
+  }
+
+  for (uint8_t row = 0; row < MatrixRows; ++row) {
+    for (uint8_t col = 0; col < MatrixCols; ++col) {
+      const uint8_t *glyph = font + (matrix->display[row][col] * FontWidth);
+
+      for (uint8_t glyphCol = 0; glyphCol < FontWidth; ++glyphCol) {
+        uint8_t colBits = pgm_read_byte(glyph + glyphCol);
+        i2c_write(colBits OLED_BITS_FILTER, 100);
+      }
+
+      // 1 column of space between chars (it's not included in the glyph)
+      //i2c_master_write(0);
+    }
+  }
+
+  matrix->dirty = false;
+
+done:
+  i2c_stop();
+#if DEBUG_TO_SCREEN
+  --displaying;
+#endif
+}
+
+void iota_gfx_flush(void) {
+  matrix_render(&display);
+}
+
+__attribute__ ((weak))
+void iota_gfx_task_user(void) {
+}
+
+void iota_gfx_task(void) {
+  iota_gfx_task_user();
+
+  if (display.dirty|| force_dirty) {
+    iota_gfx_flush();
+    force_dirty = false;
+  }
+
+  if (ScreenOffInterval !=0 && timer_elapsed(last_flush) > ScreenOffInterval) {
+    iota_gfx_off();
+  }
+}
+
+bool process_record_gfx(uint16_t keycode, keyrecord_t *record) {
+  force_dirty = true;
+  return true;
+}
+
+#endif
diff --git a/keyboards/crkbd/rev1/config.h b/keyboards/crkbd/rev1/config.h
index f7f278f2c0..60bd379724 100644
--- a/keyboards/crkbd/rev1/config.h
+++ b/keyboards/crkbd/rev1/config.h
@@ -1,6 +1,6 @@
 /*
-Copyright 2012 Jun Wako <wakojun@gmail.com>
-Copyright 2015 Jack Humbert
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
 
 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
@@ -18,64 +18,15 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #pragma once
 
-/* USB Device descriptor parameter */
-#define VENDOR_ID       0xFEED
-#define PRODUCT_ID      0x3060
-#define DEVICE_VER      0x0001
-#define MANUFACTURER    foostan
-#define PRODUCT         Corne Keyboard (crkbd)
-#define DESCRIPTION     A split keyboard with 3x6 vertically staggered keys and 3 thumb keys
-
-/* key matrix size */
-// Rows are doubled-up
-#define MATRIX_ROWS 8
-#define MATRIX_COLS 6
-#define MATRIX_ROW_PINS { D4, C6, D7, E6 }
-
-// wiring of each half
-#define MATRIX_COL_PINS { F4, F5, F6, F7, B1, B3 }
-// #define MATRIX_COL_PINS { B2, B3, B1, F7, F6, F5, F4 } //uncomment this line and comment line above if you need to reverse left-to-right key order
-
-/* define if matrix has ghost */
-//#define MATRIX_HAS_GHOST
-
-/* number of backlight levels */
-// #define BACKLIGHT_LEVELS 3
-
-/* Set 0 if debouncing isn't needed */
-#define DEBOUNCE 5
-
-/* Mechanical locking support. Use KC_LCAP, KC_LNUM or KC_LSCR instead in keymap */
-//#define LOCKING_SUPPORT_ENABLE
-/* Locking resynchronize hack */
-//#define LOCKING_RESYNC_ENABLE
-
 /* ws2812 RGB LED */
 #define RGB_DI_PIN D3
 
 #ifdef RGBLIGHT_ENABLE
-#define RGBLED_NUM 12    // Number of LEDs
+#    define RGBLED_NUM 12  // Number of LEDs
+#    define RGBLIGHT_SPLIT
 #endif
 
 #ifdef RGB_MATRIX_ENABLE
-#define RGBLED_NUM 54    // Number of LEDs
-#define DRIVER_LED_TOTAL RGBLED_NUM
+#    define RGBLED_NUM 54  // Number of LEDs
+#    define DRIVER_LED_TOTAL RGBLED_NUM
 #endif
-
-/*
- * Feature disable options
- *  These options are also useful to firmware size reduction.
- */
-
-/* disable debug print */
-// #define NO_DEBUG
-
-/* disable print */
-// #define NO_PRINT
-
-/* disable action features */
-//#define NO_ACTION_LAYER
-//#define NO_ACTION_TAPPING
-//#define NO_ACTION_ONESHOT
-//#define NO_ACTION_MACRO
-//#define NO_ACTION_FUNCTION
diff --git a/keyboards/crkbd/rev1/legacy/config.h b/keyboards/crkbd/rev1/legacy/config.h
new file mode 100644
index 0000000000..9e3676414c
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/config.h
@@ -0,0 +1,23 @@
+/*
+Copyright 2012 Jun Wako <wakojun@gmail.com>
+Copyright 2015 Jack Humbert
+
+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 <serial_config.h>
+
+#define PRODUCT         Corne Keyboard Rev.1 (Legacy Split)
diff --git a/keyboards/crkbd/rev1/legacy/i2c.c b/keyboards/crkbd/rev1/legacy/i2c.c
new file mode 100644
index 0000000000..7b45c3f866
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/i2c.c
@@ -0,0 +1,162 @@
+#include <util/twi.h>
+#include <avr/io.h>
+#include <stdlib.h>
+#include <avr/interrupt.h>
+#include <util/twi.h>
+#include <stdbool.h>
+#include "i2c.h"
+
+#if defined(USE_I2C) || defined(USE_MATRIX_I2C)
+
+// Limits the amount of we wait for any one i2c transaction.
+// Since were running SCL line 100kHz (=> 10μs/bit), and each transactions is
+// 9 bits, a single transaction will take around 90μs to complete.
+//
+// (F_CPU/SCL_CLOCK)  =>  # of μC cycles to transfer a bit
+// poll loop takes at least 8 clock cycles to execute
+#define I2C_LOOP_TIMEOUT (9+1)*(F_CPU/SCL_CLOCK)/8
+
+#define BUFFER_POS_INC() (slave_buffer_pos = (slave_buffer_pos+1)%SLAVE_BUFFER_SIZE)
+
+volatile uint8_t i2c_slave_buffer[SLAVE_BUFFER_SIZE];
+
+static volatile uint8_t slave_buffer_pos;
+static volatile bool slave_has_register_set = false;
+
+// Wait for an i2c operation to finish
+inline static
+void i2c_delay(void) {
+  uint16_t lim = 0;
+  while(!(TWCR & (1<<TWINT)) && lim < I2C_LOOP_TIMEOUT)
+    lim++;
+
+  // easier way, but will wait slightly longer
+  // _delay_us(100);
+}
+
+// Setup twi to run at 100kHz or 400kHz (see ./i2c.h SCL_CLOCK)
+void i2c_master_init(void) {
+  // no prescaler
+  TWSR = 0;
+  // Set TWI clock frequency to SCL_CLOCK. Need TWBR>10.
+  // Check datasheets for more info.
+  TWBR = ((F_CPU/SCL_CLOCK)-16)/2;
+}
+
+// Start a transaction with the given i2c slave address. The direction of the
+// transfer is set with I2C_READ and I2C_WRITE.
+// returns: 0 => success
+//          1 => error
+uint8_t i2c_master_start(uint8_t address) {
+  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTA);
+
+  i2c_delay();
+
+  // check that we started successfully
+  if ( (TW_STATUS != TW_START) && (TW_STATUS != TW_REP_START))
+    return 1;
+
+  TWDR = address;
+  TWCR = (1<<TWINT) | (1<<TWEN);
+
+  i2c_delay();
+
+  if ( (TW_STATUS != TW_MT_SLA_ACK) && (TW_STATUS != TW_MR_SLA_ACK) )
+    return 1; // slave did not acknowledge
+  else
+    return 0; // success
+}
+
+
+// Finish the i2c transaction.
+void i2c_master_stop(void) {
+  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+
+  uint16_t lim = 0;
+  while(!(TWCR & (1<<TWSTO)) && lim < I2C_LOOP_TIMEOUT)
+    lim++;
+}
+
+// Write one byte to the i2c slave.
+// returns 0 => slave ACK
+//         1 => slave NACK
+uint8_t i2c_master_write(uint8_t data) {
+  TWDR = data;
+  TWCR = (1<<TWINT) | (1<<TWEN);
+
+  i2c_delay();
+
+  // check if the slave acknowledged us
+  return (TW_STATUS == TW_MT_DATA_ACK) ? 0 : 1;
+}
+
+// Read one byte from the i2c slave. If ack=1 the slave is acknowledged,
+// if ack=0 the acknowledge bit is not set.
+// returns: byte read from i2c device
+uint8_t i2c_master_read(int ack) {
+  TWCR = (1<<TWINT) | (1<<TWEN) | (ack<<TWEA);
+
+  i2c_delay();
+  return TWDR;
+}
+
+void i2c_reset_state(void) {
+  TWCR = 0;
+}
+
+void i2c_slave_init(uint8_t address) {
+  TWAR = address << 0; // slave i2c address
+  // TWEN  - twi enable
+  // TWEA  - enable address acknowledgement
+  // TWINT - twi interrupt flag
+  // TWIE  - enable the twi interrupt
+  TWCR = (1<<TWIE) | (1<<TWEA) | (1<<TWINT) | (1<<TWEN);
+}
+
+ISR(TWI_vect);
+
+ISR(TWI_vect) {
+  uint8_t ack = 1;
+  switch(TW_STATUS) {
+    case TW_SR_SLA_ACK:
+      // this device has been addressed as a slave receiver
+      slave_has_register_set = false;
+      break;
+
+    case TW_SR_DATA_ACK:
+      // this device has received data as a slave receiver
+      // The first byte that we receive in this transaction sets the location
+      // of the read/write location of the slaves memory that it exposes over
+      // i2c.  After that, bytes will be written at slave_buffer_pos, incrementing
+      // slave_buffer_pos after each write.
+      if(!slave_has_register_set) {
+        slave_buffer_pos = TWDR;
+        // don't acknowledge the master if this memory loctaion is out of bounds
+        if ( slave_buffer_pos >= SLAVE_BUFFER_SIZE ) {
+          ack = 0;
+          slave_buffer_pos = 0;
+        }
+        slave_has_register_set = true;
+      } else {
+        i2c_slave_buffer[slave_buffer_pos] = TWDR;
+        BUFFER_POS_INC();
+      }
+      break;
+
+    case TW_ST_SLA_ACK:
+    case TW_ST_DATA_ACK:
+      // master has addressed this device as a slave transmitter and is
+      // requesting data.
+      TWDR = i2c_slave_buffer[slave_buffer_pos];
+      BUFFER_POS_INC();
+      break;
+
+    case TW_BUS_ERROR: // something went wrong, reset twi state
+      TWCR = 0;
+    default:
+      break;
+  }
+  // Reset everything, so we are ready for the next TWI interrupt
+  TWCR |= (1<<TWIE) | (1<<TWINT) | (ack<<TWEA) | (1<<TWEN);
+}
+#endif
diff --git a/keyboards/crkbd/rev1/legacy/i2c.h b/keyboards/crkbd/rev1/legacy/i2c.h
new file mode 100644
index 0000000000..710662c7ab
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/i2c.h
@@ -0,0 +1,46 @@
+#pragma once
+
+#include <stdint.h>
+
+#ifndef F_CPU
+#define F_CPU 16000000UL
+#endif
+
+#define I2C_READ 1
+#define I2C_WRITE 0
+
+#define I2C_ACK 1
+#define I2C_NACK 0
+
+#define SLAVE_BUFFER_SIZE 0x10
+
+// i2c SCL clock frequency 400kHz
+#define SCL_CLOCK  400000L
+
+extern volatile uint8_t i2c_slave_buffer[SLAVE_BUFFER_SIZE];
+
+void i2c_master_init(void);
+uint8_t i2c_master_start(uint8_t address);
+void i2c_master_stop(void);
+uint8_t i2c_master_write(uint8_t data);
+uint8_t i2c_master_read(int);
+void i2c_reset_state(void);
+void i2c_slave_init(uint8_t address);
+
+
+static inline unsigned char i2c_start_read(unsigned char addr) {
+  return i2c_master_start((addr << 1) | I2C_READ);
+}
+
+static inline unsigned char i2c_start_write(unsigned char addr) {
+  return i2c_master_start((addr << 1) | I2C_WRITE);
+}
+
+// from SSD1306 scrips
+extern unsigned char i2c_rep_start(unsigned char addr);
+extern void i2c_start_wait(unsigned char addr);
+extern unsigned char i2c_readAck(void);
+extern unsigned char i2c_readNak(void);
+extern unsigned char i2c_read(unsigned char ack);
+
+#define i2c_read(ack)  (ack) ? i2c_readAck() : i2c_readNak();
diff --git a/keyboards/crkbd/rev1/legacy/legacy.c b/keyboards/crkbd/rev1/legacy/legacy.c
new file mode 100644
index 0000000000..595ff1eaf7
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/legacy.c
@@ -0,0 +1,19 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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 "legacy.h"
diff --git a/keyboards/crkbd/rev1/legacy/legacy.h b/keyboards/crkbd/rev1/legacy/legacy.h
new file mode 100644
index 0000000000..6c6308e592
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/legacy.h
@@ -0,0 +1,21 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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 "rev1.h"
diff --git a/keyboards/crkbd/rev1/matrix.c b/keyboards/crkbd/rev1/legacy/matrix.c
index 46dead369f..46dead369f 100644
--- a/keyboards/crkbd/rev1/matrix.c
+++ b/keyboards/crkbd/rev1/legacy/matrix.c
diff --git a/keyboards/crkbd/rev1/legacy/post_config.h b/keyboards/crkbd/rev1/legacy/post_config.h
new file mode 100644
index 0000000000..b3d6346cc8
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/post_config.h
@@ -0,0 +1,27 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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
+
+#ifdef SSD1306OLED
+#    define USE_I2C
+#endif
+
+#if defined(OLED_DRIVER_ENABLE) && (defined(USE_I2C) || defined(USE_MATRIX_I2C))
+#    error Cannot use both legacy i2c driver and new i2c_master driver at the same time. Undefine USE_I2C and/or USE_MATRIX_I2C
+#endif
diff --git a/keyboards/crkbd/rev1/legacy/rules.mk b/keyboards/crkbd/rev1/legacy/rules.mk
new file mode 100644
index 0000000000..2bef242977
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/rules.mk
@@ -0,0 +1,7 @@
+CUSTOM_MATRIX = yes
+
+SRC += 	matrix.c \
+		split_util.c \
+		split_scomm.c
+
+QUANTUM_LIB_SRC += i2c.c serial.c
diff --git a/keyboards/crkbd/rev1/legacy/serial.c b/keyboards/crkbd/rev1/legacy/serial.c
new file mode 100644
index 0000000000..f6293c3dc2
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/serial.c
@@ -0,0 +1,589 @@
+/*
+ * WARNING: be careful changing this code, it is very timing dependent
+ *
+ * 2018-10-28 checked
+ *  avr-gcc 4.9.2
+ *  avr-gcc 5.4.0
+ *  avr-gcc 7.3.0
+ */
+
+#ifndef F_CPU
+#define F_CPU 16000000
+#endif
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include "serial.h"
+
+#ifdef SOFT_SERIAL_PIN
+
+#ifdef __AVR_ATmega32U4__
+  // if using ATmega32U4 I2C, can not use PD0 and PD1 in soft serial.
+  #ifdef USE_I2C
+    #if SOFT_SERIAL_PIN == D0 || SOFT_SERIAL_PIN == D1
+      #error Using ATmega32U4 I2C, so can not use PD0, PD1
+    #endif
+  #endif
+
+  #if SOFT_SERIAL_PIN >= D0 && SOFT_SERIAL_PIN <= D3
+    #define SERIAL_PIN_DDR   DDRD
+    #define SERIAL_PIN_PORT  PORTD
+    #define SERIAL_PIN_INPUT PIND
+    #if SOFT_SERIAL_PIN == D0
+      #define SERIAL_PIN_MASK _BV(PD0)
+      #define EIMSK_BIT       _BV(INT0)
+      #define EICRx_BIT       (~(_BV(ISC00) | _BV(ISC01)))
+      #define SERIAL_PIN_INTERRUPT INT0_vect
+    #elif  SOFT_SERIAL_PIN == D1
+      #define SERIAL_PIN_MASK _BV(PD1)
+      #define EIMSK_BIT       _BV(INT1)
+      #define EICRx_BIT       (~(_BV(ISC10) | _BV(ISC11)))
+      #define SERIAL_PIN_INTERRUPT INT1_vect
+    #elif  SOFT_SERIAL_PIN == D2
+      #define SERIAL_PIN_MASK _BV(PD2)
+      #define EIMSK_BIT       _BV(INT2)
+      #define EICRx_BIT       (~(_BV(ISC20) | _BV(ISC21)))
+      #define SERIAL_PIN_INTERRUPT INT2_vect
+    #elif  SOFT_SERIAL_PIN == D3
+      #define SERIAL_PIN_MASK _BV(PD3)
+      #define EIMSK_BIT       _BV(INT3)
+      #define EICRx_BIT       (~(_BV(ISC30) | _BV(ISC31)))
+      #define SERIAL_PIN_INTERRUPT INT3_vect
+    #endif
+  #elif  SOFT_SERIAL_PIN == E6
+    #define SERIAL_PIN_DDR   DDRE
+    #define SERIAL_PIN_PORT  PORTE
+    #define SERIAL_PIN_INPUT PINE
+    #define SERIAL_PIN_MASK  _BV(PE6)
+    #define EIMSK_BIT        _BV(INT6)
+    #define EICRx_BIT        (~(_BV(ISC60) | _BV(ISC61)))
+    #define SERIAL_PIN_INTERRUPT INT6_vect
+  #else
+  #error invalid SOFT_SERIAL_PIN value
+  #endif
+
+#else
+ #error serial.c now support ATmega32U4 only
+#endif
+
+//////////////// for backward compatibility ////////////////////////////////
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+/* --- USE Simple API (OLD API, compatible with let's split serial.c) */
+  #if SERIAL_SLAVE_BUFFER_LENGTH > 0
+  uint8_t volatile serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH] = {0};
+  #endif
+  #if SERIAL_MASTER_BUFFER_LENGTH > 0
+  uint8_t volatile serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH] = {0};
+  #endif
+  uint8_t volatile status0 = 0;
+
+SSTD_t transactions[] = {
+    { (uint8_t *)&status0,
+  #if SERIAL_MASTER_BUFFER_LENGTH > 0
+      sizeof(serial_master_buffer), (uint8_t *)serial_master_buffer,
+  #else
+      0, (uint8_t *)NULL,
+  #endif
+  #if SERIAL_SLAVE_BUFFER_LENGTH > 0
+      sizeof(serial_slave_buffer), (uint8_t *)serial_slave_buffer
+  #else
+      0, (uint8_t *)NULL,
+  #endif
+  }
+};
+
+void serial_master_init(void)
+{ soft_serial_initiator_init(transactions, TID_LIMIT(transactions)); }
+
+void serial_slave_init(void)
+{ soft_serial_target_init(transactions, TID_LIMIT(transactions)); }
+
+// 0 => no error
+// 1 => slave did not respond
+// 2 => checksum error
+int serial_update_buffers()
+{
+    int result;
+    result = soft_serial_transaction();
+    return result;
+}
+
+#endif // end of Simple API (OLD API, compatible with let's split serial.c)
+////////////////////////////////////////////////////////////////////////////
+
+#define ALWAYS_INLINE __attribute__((always_inline))
+#define NO_INLINE __attribute__((noinline))
+#define _delay_sub_us(x)    __builtin_avr_delay_cycles(x)
+
+// parity check
+#define ODD_PARITY 1
+#define EVEN_PARITY 0
+#define PARITY EVEN_PARITY
+
+#ifdef SERIAL_DELAY
+  // custom setup in config.h
+  // #define TID_SEND_ADJUST 2
+  // #define SERIAL_DELAY 6             // micro sec
+  // #define READ_WRITE_START_ADJUST 30 // cycles
+  // #define READ_WRITE_WIDTH_ADJUST 8 // cycles
+#else
+// ============ Standard setups ============
+
+#ifndef SELECT_SOFT_SERIAL_SPEED
+#define SELECT_SOFT_SERIAL_SPEED 1
+//  0: about 189kbps
+//  1: about 137kbps (default)
+//  2: about 75kbps
+//  3: about 39kbps
+//  4: about 26kbps
+//  5: about 20kbps
+#endif
+
+#if __GNUC__ < 6
+  #define TID_SEND_ADJUST 14
+#else
+  #define TID_SEND_ADJUST 2
+#endif
+
+#if SELECT_SOFT_SERIAL_SPEED == 0
+  // Very High speed
+  #define SERIAL_DELAY 4             // micro sec
+  #if __GNUC__ < 6
+    #define READ_WRITE_START_ADJUST 33 // cycles
+    #define READ_WRITE_WIDTH_ADJUST 3 // cycles
+  #else
+    #define READ_WRITE_START_ADJUST 34 // cycles
+    #define READ_WRITE_WIDTH_ADJUST 7 // cycles
+  #endif
+#elif SELECT_SOFT_SERIAL_SPEED == 1
+  // High speed
+  #define SERIAL_DELAY 6             // micro sec
+  #if __GNUC__ < 6
+    #define READ_WRITE_START_ADJUST 30 // cycles
+    #define READ_WRITE_WIDTH_ADJUST 3 // cycles
+  #else
+    #define READ_WRITE_START_ADJUST 33 // cycles
+    #define READ_WRITE_WIDTH_ADJUST 7 // cycles
+  #endif
+#elif SELECT_SOFT_SERIAL_SPEED == 2
+  // Middle speed
+  #define SERIAL_DELAY 12            // micro sec
+  #define READ_WRITE_START_ADJUST 30 // cycles
+  #if __GNUC__ < 6
+    #define READ_WRITE_WIDTH_ADJUST 3 // cycles
+  #else
+    #define READ_WRITE_WIDTH_ADJUST 7 // cycles
+  #endif
+#elif SELECT_SOFT_SERIAL_SPEED == 3
+  // Low speed
+  #define SERIAL_DELAY 24            // micro sec
+  #define READ_WRITE_START_ADJUST 30 // cycles
+  #if __GNUC__ < 6
+    #define READ_WRITE_WIDTH_ADJUST 3 // cycles
+  #else
+    #define READ_WRITE_WIDTH_ADJUST 7 // cycles
+  #endif
+#elif SELECT_SOFT_SERIAL_SPEED == 4
+  // Very Low speed
+  #define SERIAL_DELAY 36            // micro sec
+  #define READ_WRITE_START_ADJUST 30 // cycles
+  #if __GNUC__ < 6
+    #define READ_WRITE_WIDTH_ADJUST 3 // cycles
+  #else
+    #define READ_WRITE_WIDTH_ADJUST 7 // cycles
+  #endif
+#elif SELECT_SOFT_SERIAL_SPEED == 5
+  // Ultra Low speed
+  #define SERIAL_DELAY 48            // micro sec
+  #define READ_WRITE_START_ADJUST 30 // cycles
+  #if __GNUC__ < 6
+    #define READ_WRITE_WIDTH_ADJUST 3 // cycles
+  #else
+    #define READ_WRITE_WIDTH_ADJUST 7 // cycles
+  #endif
+#else
+#error invalid SELECT_SOFT_SERIAL_SPEED value
+#endif /* SELECT_SOFT_SERIAL_SPEED */
+#endif /* SERIAL_DELAY */
+
+#define SERIAL_DELAY_HALF1 (SERIAL_DELAY/2)
+#define SERIAL_DELAY_HALF2 (SERIAL_DELAY - SERIAL_DELAY/2)
+
+#define SLAVE_INT_WIDTH_US 1
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+  #define SLAVE_INT_RESPONSE_TIME SERIAL_DELAY
+#else
+  #define SLAVE_INT_ACK_WIDTH_UNIT 2
+  #define SLAVE_INT_ACK_WIDTH 4
+#endif
+
+static SSTD_t *Transaction_table = NULL;
+static uint8_t Transaction_table_size = 0;
+
+inline static void serial_delay(void) ALWAYS_INLINE;
+inline static
+void serial_delay(void) {
+  _delay_us(SERIAL_DELAY);
+}
+
+inline static void serial_delay_half1(void) ALWAYS_INLINE;
+inline static
+void serial_delay_half1(void) {
+  _delay_us(SERIAL_DELAY_HALF1);
+}
+
+inline static void serial_delay_half2(void) ALWAYS_INLINE;
+inline static
+void serial_delay_half2(void) {
+  _delay_us(SERIAL_DELAY_HALF2);
+}
+
+inline static void serial_output(void) ALWAYS_INLINE;
+inline static
+void serial_output(void) {
+  SERIAL_PIN_DDR |= SERIAL_PIN_MASK;
+}
+
+// make the serial pin an input with pull-up resistor
+inline static void serial_input_with_pullup(void) ALWAYS_INLINE;
+inline static
+void serial_input_with_pullup(void) {
+  SERIAL_PIN_DDR  &= ~SERIAL_PIN_MASK;
+  SERIAL_PIN_PORT |= SERIAL_PIN_MASK;
+}
+
+inline static uint8_t serial_read_pin(void) ALWAYS_INLINE;
+inline static
+uint8_t serial_read_pin(void) {
+  return !!(SERIAL_PIN_INPUT & SERIAL_PIN_MASK);
+}
+
+inline static void serial_low(void) ALWAYS_INLINE;
+inline static
+void serial_low(void) {
+  SERIAL_PIN_PORT &= ~SERIAL_PIN_MASK;
+}
+
+inline static void serial_high(void) ALWAYS_INLINE;
+inline static
+void serial_high(void) {
+  SERIAL_PIN_PORT |= SERIAL_PIN_MASK;
+}
+
+void soft_serial_initiator_init(SSTD_t *sstd_table, int sstd_table_size)
+{
+    Transaction_table = sstd_table;
+    Transaction_table_size = (uint8_t)sstd_table_size;
+    serial_output();
+    serial_high();
+}
+
+void soft_serial_target_init(SSTD_t *sstd_table, int sstd_table_size)
+{
+    Transaction_table = sstd_table;
+    Transaction_table_size = (uint8_t)sstd_table_size;
+    serial_input_with_pullup();
+
+    // Enable INT0-INT3,INT6
+    EIMSK |= EIMSK_BIT;
+#if SERIAL_PIN_MASK == _BV(PE6)
+    // Trigger on falling edge of INT6
+    EICRB &= EICRx_BIT;
+#else
+    // Trigger on falling edge of INT0-INT3
+    EICRA &= EICRx_BIT;
+#endif
+}
+
+// Used by the sender to synchronize timing with the reciver.
+static void sync_recv(void) NO_INLINE;
+static
+void sync_recv(void) {
+  for (uint8_t i = 0; i < SERIAL_DELAY*5 && serial_read_pin(); i++ ) {
+  }
+  // This shouldn't hang if the target disconnects because the
+  // serial line will float to high if the target does disconnect.
+  while (!serial_read_pin());
+}
+
+// Used by the reciver to send a synchronization signal to the sender.
+static void sync_send(void) NO_INLINE;
+static
+void sync_send(void) {
+  serial_low();
+  serial_delay();
+  serial_high();
+}
+
+// Reads a byte from the serial line
+static uint8_t serial_read_chunk(uint8_t *pterrcount, uint8_t bit) NO_INLINE;
+static uint8_t serial_read_chunk(uint8_t *pterrcount, uint8_t bit) {
+    uint8_t byte, i, p, pb;
+
+  _delay_sub_us(READ_WRITE_START_ADJUST);
+  for( i = 0, byte = 0, p = PARITY; i < bit; i++ ) {
+      serial_delay_half1();   // read the middle of pulses
+      if( serial_read_pin() ) {
+          byte = (byte << 1) | 1; p ^= 1;
+      } else {
+          byte = (byte << 1) | 0; p ^= 0;
+      }
+      _delay_sub_us(READ_WRITE_WIDTH_ADJUST);
+      serial_delay_half2();
+  }
+  /* recive parity bit */
+  serial_delay_half1();   // read the middle of pulses
+  pb = serial_read_pin();
+  _delay_sub_us(READ_WRITE_WIDTH_ADJUST);
+  serial_delay_half2();
+
+  *pterrcount += (p != pb)? 1 : 0;
+
+  return byte;
+}
+
+// Sends a byte with MSB ordering
+void serial_write_chunk(uint8_t data, uint8_t bit) NO_INLINE;
+void serial_write_chunk(uint8_t data, uint8_t bit) {
+    uint8_t b, p;
+    for( p = PARITY, b = 1<<(bit-1); b ; b >>= 1) {
+        if(data & b) {
+            serial_high(); p ^= 1;
+        } else {
+            serial_low();  p ^= 0;
+        }
+        serial_delay();
+    }
+    /* send parity bit */
+    if(p & 1) { serial_high(); }
+    else      { serial_low(); }
+    serial_delay();
+
+    serial_low(); // sync_send() / senc_recv() need raise edge
+}
+
+static void serial_send_packet(uint8_t *buffer, uint8_t size) NO_INLINE;
+static
+void serial_send_packet(uint8_t *buffer, uint8_t size) {
+  for (uint8_t i = 0; i < size; ++i) {
+    uint8_t data;
+    data = buffer[i];
+    sync_send();
+    serial_write_chunk(data,8);
+  }
+}
+
+static uint8_t serial_recive_packet(uint8_t *buffer, uint8_t size) NO_INLINE;
+static
+uint8_t serial_recive_packet(uint8_t *buffer, uint8_t size) {
+  uint8_t pecount = 0;
+  for (uint8_t i = 0; i < size; ++i) {
+    uint8_t data;
+    sync_recv();
+    data = serial_read_chunk(&pecount, 8);
+    buffer[i] = data;
+  }
+  return pecount == 0;
+}
+
+inline static
+void change_sender2reciver(void) {
+    sync_send();          //0
+    serial_delay_half1(); //1
+    serial_low();         //2
+    serial_input_with_pullup(); //2
+    serial_delay_half1(); //3
+}
+
+inline static
+void change_reciver2sender(void) {
+    sync_recv();     //0
+    serial_delay();  //1
+    serial_low();    //3
+    serial_output(); //3
+    serial_delay_half1(); //4
+}
+
+static inline uint8_t nibble_bits_count(uint8_t bits)
+{
+    bits = (bits & 0x5) + (bits >> 1 & 0x5);
+    bits = (bits & 0x3) + (bits >> 2 & 0x3);
+    return bits;
+}
+
+// interrupt handle to be used by the target device
+ISR(SERIAL_PIN_INTERRUPT) {
+
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+  serial_low();
+  serial_output();
+  SSTD_t *trans = Transaction_table;
+#else
+  // recive transaction table index
+  uint8_t tid, bits;
+  uint8_t pecount = 0;
+  sync_recv();
+  bits = serial_read_chunk(&pecount,7);
+  tid = bits>>3;
+  bits = (bits&7) != nibble_bits_count(tid);
+  if( bits || pecount> 0 || tid > Transaction_table_size ) {
+      return;
+  }
+  serial_delay_half1();
+
+  serial_high(); // response step1 low->high
+  serial_output();
+  _delay_sub_us(SLAVE_INT_ACK_WIDTH_UNIT*SLAVE_INT_ACK_WIDTH);
+  SSTD_t *trans = &Transaction_table[tid];
+  serial_low(); // response step2 ack high->low
+#endif
+
+  // target send phase
+  if( trans->target2initiator_buffer_size > 0 )
+      serial_send_packet((uint8_t *)trans->target2initiator_buffer,
+                         trans->target2initiator_buffer_size);
+  // target switch to input
+  change_sender2reciver();
+
+  // target recive phase
+  if( trans->initiator2target_buffer_size > 0 ) {
+      if (serial_recive_packet((uint8_t *)trans->initiator2target_buffer,
+                               trans->initiator2target_buffer_size) ) {
+          *trans->status = TRANSACTION_ACCEPTED;
+      } else {
+          *trans->status = TRANSACTION_DATA_ERROR;
+      }
+  } else {
+      *trans->status = TRANSACTION_ACCEPTED;
+  }
+
+  sync_recv(); //weit initiator output to high
+}
+
+/////////
+//  start transaction by initiator
+//
+// int  soft_serial_transaction(int sstd_index)
+//
+// Returns:
+//    TRANSACTION_END
+//    TRANSACTION_NO_RESPONSE
+//    TRANSACTION_DATA_ERROR
+// this code is very time dependent, so we need to disable interrupts
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+int  soft_serial_transaction(void) {
+  SSTD_t *trans = Transaction_table;
+#else
+int  soft_serial_transaction(int sstd_index) {
+  if( sstd_index > Transaction_table_size )
+      return TRANSACTION_TYPE_ERROR;
+  SSTD_t *trans = &Transaction_table[sstd_index];
+#endif
+  cli();
+
+  // signal to the target that we want to start a transaction
+  serial_output();
+  serial_low();
+  _delay_us(SLAVE_INT_WIDTH_US);
+
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+  // wait for the target response
+  serial_input_with_pullup();
+  _delay_us(SLAVE_INT_RESPONSE_TIME);
+
+  // check if the target is present
+  if (serial_read_pin()) {
+    // target failed to pull the line low, assume not present
+    serial_output();
+    serial_high();
+    *trans->status = TRANSACTION_NO_RESPONSE;
+    sei();
+    return TRANSACTION_NO_RESPONSE;
+  }
+
+#else
+  // send transaction table index
+  int tid = (sstd_index<<3) | (7 & nibble_bits_count(sstd_index));
+  sync_send();
+  _delay_sub_us(TID_SEND_ADJUST);
+  serial_write_chunk(tid, 7);
+  serial_delay_half1();
+
+  // wait for the target response (step1 low->high)
+  serial_input_with_pullup();
+  while( !serial_read_pin() ) {
+      _delay_sub_us(2);
+  }
+
+  // check if the target is present (step2 high->low)
+  for( int i = 0; serial_read_pin(); i++ ) {
+      if (i > SLAVE_INT_ACK_WIDTH + 1) {
+          // slave failed to pull the line low, assume not present
+          serial_output();
+          serial_high();
+          *trans->status = TRANSACTION_NO_RESPONSE;
+          sei();
+          return TRANSACTION_NO_RESPONSE;
+      }
+      _delay_sub_us(SLAVE_INT_ACK_WIDTH_UNIT);
+  }
+#endif
+
+  // initiator recive phase
+  // if the target is present syncronize with it
+  if( trans->target2initiator_buffer_size > 0 ) {
+      if (!serial_recive_packet((uint8_t *)trans->target2initiator_buffer,
+                                trans->target2initiator_buffer_size) ) {
+          serial_output();
+          serial_high();
+          *trans->status = TRANSACTION_DATA_ERROR;
+          sei();
+          return TRANSACTION_DATA_ERROR;
+      }
+   }
+
+  // initiator switch to output
+  change_reciver2sender();
+
+  // initiator send phase
+  if( trans->initiator2target_buffer_size > 0 ) {
+      serial_send_packet((uint8_t *)trans->initiator2target_buffer,
+                         trans->initiator2target_buffer_size);
+  }
+
+  // always, release the line when not in use
+  sync_send();
+
+  *trans->status = TRANSACTION_END;
+  sei();
+  return TRANSACTION_END;
+}
+
+#ifdef SERIAL_USE_MULTI_TRANSACTION
+int soft_serial_get_and_clean_status(int sstd_index) {
+    SSTD_t *trans = &Transaction_table[sstd_index];
+    cli();
+    int retval = *trans->status;
+    *trans->status = 0;;
+    sei();
+    return retval;
+}
+#endif
+
+#endif
+
+// Helix serial.c history
+//   2018-1-29 fork from let's split and add PD2, modify sync_recv() (#2308, bceffdefc)
+//   2018-6-28 bug fix master to slave comm and speed up (#3255, 1038bbef4)
+//             (adjusted with avr-gcc 4.9.2)
+//   2018-7-13 remove USE_SERIAL_PD2 macro (#3374, f30d6dd78)
+//             (adjusted with avr-gcc 4.9.2)
+//   2018-8-11 add support multi-type transaction (#3608, feb5e4aae)
+//             (adjusted with avr-gcc 4.9.2)
+//   2018-10-21 fix serial and RGB animation conflict (#4191, 4665e4fff)
+//             (adjusted with avr-gcc 7.3.0)
+//   2018-10-28 re-adjust compiler depend value of delay (#4269, 8517f8a66)
+//             (adjusted with avr-gcc 5.4.0, 7.3.0)
diff --git a/keyboards/crkbd/rev1/legacy/serial.h b/keyboards/crkbd/rev1/legacy/serial.h
new file mode 100644
index 0000000000..7e0c0847a4
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/serial.h
@@ -0,0 +1,84 @@
+#ifndef SOFT_SERIAL_H
+#define SOFT_SERIAL_H
+
+#include <stdbool.h>
+
+// /////////////////////////////////////////////////////////////////
+// Need Soft Serial defines in config.h
+// /////////////////////////////////////////////////////////////////
+// ex.
+//  #define SOFT_SERIAL_PIN ??   // ?? = D0,D1,D2,D3,E6
+//  OPTIONAL: #define SELECT_SOFT_SERIAL_SPEED ? // ? = 1,2,3,4,5
+//                                               //  1: about 137kbps (default)
+//                                               //  2: about 75kbps
+//                                               //  3: about 39kbps
+//                                               //  4: about 26kbps
+//                                               //  5: about 20kbps
+//
+// //// USE Simple API (OLD API, compatible with let's split serial.c)
+// ex.
+//  #define SERIAL_SLAVE_BUFFER_LENGTH MATRIX_ROWS/2
+//  #define SERIAL_MASTER_BUFFER_LENGTH 1
+//
+// //// USE flexible API (using multi-type transaction function)
+//  #define SERIAL_USE_MULTI_TRANSACTION
+//
+// /////////////////////////////////////////////////////////////////
+
+
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+/* --- USE Simple API (OLD API, compatible with let's split serial.c) */
+#if SERIAL_SLAVE_BUFFER_LENGTH > 0
+extern volatile uint8_t serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH];
+#endif
+#if SERIAL_MASTER_BUFFER_LENGTH > 0
+extern volatile uint8_t serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH];
+#endif
+
+void serial_master_init(void);
+void serial_slave_init(void);
+int serial_update_buffers(void);
+
+#endif // USE Simple API
+
+// Soft Serial Transaction Descriptor
+typedef struct _SSTD_t  {
+    uint8_t *status;
+    uint8_t initiator2target_buffer_size;
+    uint8_t *initiator2target_buffer;
+    uint8_t target2initiator_buffer_size;
+    uint8_t *target2initiator_buffer;
+} SSTD_t;
+#define TID_LIMIT( table ) (sizeof(table) / sizeof(SSTD_t))
+
+// initiator is transaction start side
+void soft_serial_initiator_init(SSTD_t *sstd_table, int sstd_table_size);
+// target is interrupt accept side
+void soft_serial_target_init(SSTD_t *sstd_table, int sstd_table_size);
+
+// initiator resullt
+#define TRANSACTION_END 0
+#define TRANSACTION_NO_RESPONSE 0x1
+#define TRANSACTION_DATA_ERROR  0x2
+#define TRANSACTION_TYPE_ERROR  0x4
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+int  soft_serial_transaction(void);
+#else
+int  soft_serial_transaction(int sstd_index);
+#endif
+
+// target status
+// *SSTD_t.status has
+//   initiator:
+//       TRANSACTION_END
+//    or TRANSACTION_NO_RESPONSE
+//    or TRANSACTION_DATA_ERROR
+//   target:
+//       TRANSACTION_DATA_ERROR
+//    or TRANSACTION_ACCEPTED
+#define TRANSACTION_ACCEPTED 0x8
+#ifdef SERIAL_USE_MULTI_TRANSACTION
+int  soft_serial_get_and_clean_status(int sstd_index);
+#endif
+
+#endif /* SOFT_SERIAL_H */
diff --git a/keyboards/crkbd/rev1/legacy/serial_config.h b/keyboards/crkbd/rev1/legacy/serial_config.h
new file mode 100644
index 0000000000..40d11d4de2
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/serial_config.h
@@ -0,0 +1,22 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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/>.
+*/
+
+#ifndef SOFT_SERIAL_PIN
+#define SOFT_SERIAL_PIN D2
+#define SERIAL_USE_MULTI_TRANSACTION
+#endif
diff --git a/keyboards/crkbd/rev1/legacy/serial_config_simpleapi.h b/keyboards/crkbd/rev1/legacy/serial_config_simpleapi.h
new file mode 100644
index 0000000000..bd152ddda3
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/serial_config_simpleapi.h
@@ -0,0 +1,23 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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
+
+#undef SERIAL_USE_MULTI_TRANSACTION
+#define SERIAL_SLAVE_BUFFER_LENGTH MATRIX_ROWS/2
+#define SERIAL_MASTER_BUFFER_LENGTH MATRIX_ROWS/2
diff --git a/keyboards/crkbd/rev1/split_scomm.c b/keyboards/crkbd/rev1/legacy/split_scomm.c
index 12b00f6840..c14bb32a43 100644
--- a/keyboards/crkbd/rev1/split_scomm.c
+++ b/keyboards/crkbd/rev1/legacy/split_scomm.c
@@ -1,3 +1,21 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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/>.
+*/
+
 #ifdef USE_SERIAL
 #ifdef SERIAL_USE_MULTI_TRANSACTION
 /* --- USE flexible API (using multi-type transaction function) --- */
diff --git a/keyboards/crkbd/rev1/split_scomm.h b/keyboards/crkbd/rev1/legacy/split_scomm.h
index 873d8939d8..47f0ca1b9d 100644
--- a/keyboards/crkbd/rev1/split_scomm.h
+++ b/keyboards/crkbd/rev1/legacy/split_scomm.h
@@ -1,3 +1,21 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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/>.
+*/
+
 #ifndef SPLIT_COMM_H
 #define SPLIT_COMM_H
 
diff --git a/keyboards/crkbd/rev1/split_util.c b/keyboards/crkbd/rev1/legacy/split_util.c
index b642a734cc..d0fee04ad6 100644
--- a/keyboards/crkbd/rev1/split_util.c
+++ b/keyboards/crkbd/rev1/legacy/split_util.c
@@ -1,3 +1,21 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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 <avr/io.h>
 #include <avr/wdt.h>
 #include <avr/power.h>
@@ -14,7 +32,7 @@
 #endif
 
 #ifdef USE_MATRIX_I2C
-#  include "i2c.h"
+#  include "i2c_master.h"
 #else
 #  include "split_scomm.h"
 #endif
@@ -81,7 +99,7 @@ __attribute__((weak)) bool has_usb(void) {
 static void keyboard_master_setup(void) {
 
 #ifdef USE_MATRIX_I2C
-    i2c_master_init();
+    i2c_init();
 #else
     serial_master_init();
 #endif
diff --git a/keyboards/crkbd/rev1/legacy/split_util.h b/keyboards/crkbd/rev1/legacy/split_util.h
new file mode 100644
index 0000000000..414763bff2
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/split_util.h
@@ -0,0 +1,37 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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/>.
+*/
+
+#ifndef SPLIT_KEYBOARD_UTIL_H
+#define SPLIT_KEYBOARD_UTIL_H
+
+#include <stdbool.h>
+#include "eeconfig.h"
+
+#define SLAVE_I2C_ADDRESS           0x32
+
+extern volatile bool isLeftHand;
+
+// slave version of matix scan, defined in matrix.c
+void matrix_slave_scan(void);
+
+void split_keyboard_setup(void);
+bool has_usb(void);
+
+void matrix_master_OLED_init (void);
+
+#endif
diff --git a/keyboards/crkbd/rev1/legacy/ssd1306.c b/keyboards/crkbd/rev1/legacy/ssd1306.c
new file mode 100644
index 0000000000..b04b7e15c1
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/ssd1306.c
@@ -0,0 +1,357 @@
+#ifdef SSD1306OLED
+
+#include "ssd1306.h"
+#include "i2c.h"
+#include <string.h>
+#include "print.h"
+#ifdef PROTOCOL_LUFA
+#include "lufa.h"
+#endif
+#include "sendchar.h"
+#include "timer.h"
+
+struct CharacterMatrix display;
+
+extern const unsigned char font[] PROGMEM;
+
+#ifndef OLED_BLANK_CHAR
+#define OLED_BLANK_CHAR ' '
+#endif
+
+#ifndef OLED_BITS_FILTER
+#define OLED_BITS_FILTER
+#endif
+
+// Set this to 1 to help diagnose early startup problems
+// when testing power-on with ble.  Turn it off otherwise,
+// as the latency of printing most of the debug info messes
+// with the matrix scan, causing keys to drop.
+#define DEBUG_TO_SCREEN 0
+
+//static uint16_t last_battery_update;
+//static uint32_t vbat;
+//#define BatteryUpdateInterval 10000 /* milliseconds */
+
+// 'last_flush' is declared as uint16_t,
+// so this must be less than 65535
+#ifndef ScreenOffInterval
+#define ScreenOffInterval 60000 /* milliseconds */
+#endif
+
+#if DEBUG_TO_SCREEN
+static uint8_t displaying;
+#endif
+static uint16_t last_flush;
+
+static bool force_dirty = true;
+
+// Write command sequence.
+// Returns true on success.
+static inline bool _send_cmd1(uint8_t cmd) {
+  bool res = false;
+
+  if (i2c_start_write(SSD1306_ADDRESS)) {
+    xprintf("failed to start write to %d\n", SSD1306_ADDRESS);
+    goto done;
+  }
+
+  if (i2c_master_write(0x0 /* command byte follows */)) {
+    print("failed to write control byte\n");
+
+    goto done;
+  }
+
+  if (i2c_master_write(cmd)) {
+    xprintf("failed to write command %d\n", cmd);
+    goto done;
+  }
+  res = true;
+done:
+  i2c_master_stop();
+  return res;
+}
+
+#define send_cmd1(c) if (!_send_cmd1(c)) {goto done;}
+#define send_cmds(c) if (!_send_cmds(c,sizeof(c))) {goto done;}
+#define cmd1(X) X
+#define cmd2(X,Y) X,Y
+#define cmd3(X,Y,Z) X,Y,Z
+
+static bool _send_cmds(const uint8_t* p,uint8_t sz) {
+  for(uint8_t i=sz;i;i--) {
+    send_cmd1( pgm_read_byte(p++) );
+  }
+  return true;
+done:
+  return false;
+}
+
+#define SEND_CMDS(...) {static const uint8_t _cmds[] PROGMEM = { __VA_ARGS__,0 };send_cmds(_cmds);}
+
+static void clear_display(void) {
+  matrix_clear(&display);
+
+  // Clear all of the display bits (there can be random noise
+  // in the RAM on startup)
+  SEND_CMDS(
+    cmd3(PageAddr, 0, (DisplayHeight / 8) - 1),
+    cmd3(ColumnAddr, 0, DisplayWidth - 1)
+  );
+
+  if (i2c_start_write(SSD1306_ADDRESS)) {
+    goto done;
+  }
+  if (i2c_master_write(0x40)) {
+    // Data mode
+    goto done;
+  }
+  for (uint8_t row = MatrixRows;row; row--) {
+    for (uint8_t col = DisplayWidth; col; col--) {
+      i2c_master_write(0);
+    }
+  }
+
+  display.dirty = false;
+
+done:
+  i2c_master_stop();
+}
+
+#if DEBUG_TO_SCREEN
+#undef sendchar
+static int8_t capture_sendchar(uint8_t c) {
+  sendchar(c);
+  iota_gfx_write_char(c);
+
+  if (!displaying) {
+    iota_gfx_flush();
+  }
+  return 0;
+}
+#endif
+
+bool iota_gfx_init(bool rotate) {
+  bool success = false;
+
+  i2c_master_init();
+  SEND_CMDS(
+    cmd1(DisplayOff),
+    cmd2(SetDisplayClockDiv, 0x80),
+    cmd2(SetMultiPlex, DisplayHeight - 1),
+    cmd2(SetDisplayOffset, 0),
+    cmd1(SetStartLine | 0x0),
+    cmd2(SetChargePump, 0x14 /* Enable */),
+    cmd2(SetMemoryMode, 0 /* horizontal addressing */)
+  );
+
+  if(rotate){
+    // the following Flip the display orientation 180 degrees
+  SEND_CMDS(
+    cmd1(SegRemap),
+    cmd1(ComScanInc)
+  );
+  }else{
+    // Flips the display orientation 0 degrees
+  SEND_CMDS(
+      cmd1(SegRemap | 0x1),
+      cmd1(ComScanDec)
+    );
+  }
+
+  SEND_CMDS(
+#ifdef SSD1306_128X64
+	cmd2(SetComPins, 0x12),
+#else
+	cmd2(SetComPins, 0x2),
+#endif
+    cmd2(SetContrast, 0x8f),
+    cmd2(SetPreCharge, 0xf1),
+    cmd2(SetVComDetect, 0x40),
+    cmd1(DisplayAllOnResume),
+    cmd1(NormalDisplay),
+    cmd1(DeActivateScroll),
+    cmd1(DisplayOn),
+
+    cmd2(SetContrast, 0) // Dim
+  );
+
+  clear_display();
+
+  success = true;
+
+  iota_gfx_flush();
+
+#if DEBUG_TO_SCREEN
+  print_set_sendchar(capture_sendchar);
+#endif
+
+done:
+  return success;
+}
+
+bool iota_gfx_off(void) {
+  bool success = false;
+
+  send_cmd1(DisplayOff);
+  success = true;
+
+done:
+  return success;
+}
+
+bool iota_gfx_on(void) {
+  bool success = false;
+
+  send_cmd1(DisplayOn);
+  success = true;
+
+done:
+  return success;
+}
+
+void matrix_write_char_inner(struct CharacterMatrix *matrix, uint8_t c) {
+  *matrix->cursor = c;
+  ++matrix->cursor;
+
+  if (matrix->cursor - &matrix->display[0][0] == sizeof(matrix->display)) {
+    // We went off the end; scroll the display upwards by one line
+    memmove(&matrix->display[0], &matrix->display[1],
+            MatrixCols * (MatrixRows - 1));
+    matrix->cursor = &matrix->display[MatrixRows - 1][0];
+    memset(matrix->cursor, OLED_BLANK_CHAR, MatrixCols);
+  }
+}
+
+void matrix_write_char(struct CharacterMatrix *matrix, uint8_t c) {
+  matrix->dirty = true;
+
+  if (c == '\n') {
+    // Clear to end of line from the cursor and then move to the
+    // start of the next line
+    uint8_t cursor_col = (matrix->cursor - &matrix->display[0][0]) % MatrixCols;
+
+    while (cursor_col++ < MatrixCols) {
+      matrix_write_char_inner(matrix, OLED_BLANK_CHAR);
+    }
+    return;
+  }
+
+  matrix_write_char_inner(matrix, c);
+}
+
+void iota_gfx_write_char(uint8_t c) {
+  matrix_write_char(&display, c);
+}
+
+void matrix_write(struct CharacterMatrix *matrix, const char *data) {
+  while (*data) {
+    matrix_write_char(matrix, *data);
+    ++data;
+  }
+}
+
+void matrix_write_ln(struct CharacterMatrix *matrix, const char *data) {
+  matrix_write(matrix, data);
+  matrix_write(matrix, "\n");
+}
+
+void iota_gfx_write(const char *data) {
+  matrix_write(&display, data);
+}
+
+void matrix_write_P(struct CharacterMatrix *matrix, const char *data) {
+  while (true) {
+    uint8_t c = pgm_read_byte(data);
+    if (c == 0) {
+      return;
+    }
+    matrix_write_char(matrix, c);
+    ++data;
+  }
+}
+
+void iota_gfx_write_P(const char *data) {
+  matrix_write_P(&display, data);
+}
+
+void matrix_clear(struct CharacterMatrix *matrix) {
+  memset(matrix->display, OLED_BLANK_CHAR, sizeof(matrix->display));
+  matrix->cursor = &matrix->display[0][0];
+  matrix->dirty = true;
+}
+
+void iota_gfx_clear_screen(void) {
+  matrix_clear(&display);
+}
+
+void matrix_render(struct CharacterMatrix *matrix) {
+  last_flush = timer_read();
+  iota_gfx_on();
+#if DEBUG_TO_SCREEN
+  ++displaying;
+#endif
+
+  // Move to the home position
+  SEND_CMDS(
+    cmd3(PageAddr, 0, MatrixRows - 1),
+    cmd3(ColumnAddr, 0, (MatrixCols * FontWidth) - 1)
+  );
+
+  if (i2c_start_write(SSD1306_ADDRESS)) {
+    goto done;
+  }
+  if (i2c_master_write(0x40)) {
+    // Data mode
+    goto done;
+  }
+
+  for (uint8_t row = 0; row < MatrixRows; ++row) {
+    for (uint8_t col = 0; col < MatrixCols; ++col) {
+      const uint8_t *glyph = font + (matrix->display[row][col] * FontWidth);
+
+      for (uint8_t glyphCol = 0; glyphCol < FontWidth; ++glyphCol) {
+        uint8_t colBits = pgm_read_byte(glyph + glyphCol);
+        i2c_master_write(colBits OLED_BITS_FILTER);
+      }
+
+      // 1 column of space between chars (it's not included in the glyph)
+      //i2c_master_write(0);
+    }
+  }
+
+  matrix->dirty = false;
+
+done:
+  i2c_master_stop();
+#if DEBUG_TO_SCREEN
+  --displaying;
+#endif
+}
+
+void iota_gfx_flush(void) {
+  matrix_render(&display);
+}
+
+__attribute__ ((weak))
+void iota_gfx_task_user(void) {
+}
+
+void iota_gfx_task(void) {
+  iota_gfx_task_user();
+
+  if (display.dirty|| force_dirty) {
+    iota_gfx_flush();
+    force_dirty = false;
+  }
+
+  if (ScreenOffInterval !=0 && timer_elapsed(last_flush) > ScreenOffInterval) {
+    iota_gfx_off();
+  }
+}
+
+bool process_record_gfx(uint16_t keycode, keyrecord_t *record) {
+  force_dirty = true;
+  return true;
+}
+
+#endif
diff --git a/keyboards/crkbd/rev1/rev1.c b/keyboards/crkbd/rev1/rev1.c
index b26292af5b..5e4e6560f0 100644
--- a/keyboards/crkbd/rev1/rev1.c
+++ b/keyboards/crkbd/rev1/rev1.c
@@ -1,4 +1,21 @@
-#include "crkbd.h"
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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 "rev1.h"
 
 #ifdef RGB_MATRIX_ENABLE
 
@@ -68,11 +85,12 @@ led_config_t g_led_config = { {
 } };
 #endif
 
-__attribute__((weak))
-void matrix_init_user(void) {}
-
 void matrix_init_kb(void) {
 
+#ifdef KEYBOARD_crkbd_rev1_common
+    is_master = (uint8_t)is_keyboard_master();
+#endif
+
 #ifdef RGB_MATRIX_ENABLE
     if (!isLeftHand) {
         g_led_config = (led_config_t){ {
@@ -107,3 +125,9 @@ void matrix_init_kb(void) {
 #endif
     matrix_init_user();
 }
+
+#ifdef SSD1306OLED
+bool process_record_kb(uint16_t keycode, keyrecord_t *record) {
+  return process_record_gfx(keycode,record) && process_record_user(keycode, record);
+}
+#endif
diff --git a/keyboards/crkbd/rev1/rev1.h b/keyboards/crkbd/rev1/rev1.h
index 2244b87f17..ce88068e64 100644
--- a/keyboards/crkbd/rev1/rev1.h
+++ b/keyboards/crkbd/rev1/rev1.h
@@ -1,25 +1,41 @@
+/*
+Copyright 2019 @foostan
+Copyright 2020 Drashna Jaelre <@drashna>
+
+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
 
+extern uint8_t is_master;
+
 #include "crkbd.h"
+#if defined(KEYBOARD_crkbd_rev1_legacy)
+#    include "legacy.h"
+#elif defined(KEYBOARD_crkbd_rev1_common)
+#    include "common.h"
+#endif
 
 #include "quantum.h"
-
+#include "split_util.h"
 #ifdef PROTOCOL_LUFA
-    #include "lufa.h"
-    #include "split_util.h"
+#    include "lufa.h"
 #endif
-
 #ifdef SSD1306OLED
-    #include "ssd1306.h"
+#    include "ssd1306.h"
 #endif
 
-#ifdef USE_I2C
-    #include <stddef.h>
-    #ifdef __AVR__
-        #include <avr/interrupt.h>
-        #include <avr/io.h>
-    #endif
-#endif
 
 // clang-format off
 #define LAYOUT_split_3x6_3( \
@@ -62,7 +78,7 @@
   L20, L21, L22, L23, L24, L25,           R20, R21, R22, R23, R24, R25, \
                       L30, L31, L32, R30, R31, R32 \
   ) \
-  LAYOUT( \
+  LAYOUT_split_3x6_3( \
     KC_##L00, KC_##L01, KC_##L02, KC_##L03, KC_##L04, KC_##L05,                     KC_##R00, KC_##R01, KC_##R02, KC_##R03, KC_##R04, KC_##R05, \
     KC_##L10, KC_##L11, KC_##L12, KC_##L13, KC_##L14, KC_##L15,                     KC_##R10, KC_##R11, KC_##R12, KC_##R13, KC_##R14, KC_##R15, \
     KC_##L20, KC_##L21, KC_##L22, KC_##L23, KC_##L24, KC_##L25,                     KC_##R20, KC_##R21, KC_##R22, KC_##R23, KC_##R24, KC_##R25, \
diff --git a/keyboards/crkbd/rev1/rules.mk b/keyboards/crkbd/rev1/rules.mk
index 21cee6bcf7..6bc5a5b038 100644
--- a/keyboards/crkbd/rev1/rules.mk
+++ b/keyboards/crkbd/rev1/rules.mk
@@ -1,5 +1,3 @@
-SRC += 	matrix.c \
-		split_util.c \
-		split_scomm.c
+LIB_SRC += ssd1306.c
 
-LAYOUTS = split_3x5_3 split_3x6_3
+DEFAULT_FOLDER = crkbd/rev1/legacy
diff --git a/keyboards/crkbd/rev1/serial_config.h b/keyboards/crkbd/rev1/serial_config.h
deleted file mode 100644
index 4fab8e8ddf..0000000000
--- a/keyboards/crkbd/rev1/serial_config.h
+++ /dev/null
@@ -1,4 +0,0 @@
-#ifndef SOFT_SERIAL_PIN
-#define SOFT_SERIAL_PIN D2
-#define SERIAL_USE_MULTI_TRANSACTION
-#endif
diff --git a/keyboards/crkbd/rev1/serial_config_simpleapi.h b/keyboards/crkbd/rev1/serial_config_simpleapi.h
deleted file mode 100644
index 0e1dd9e4ac..0000000000
--- a/keyboards/crkbd/rev1/serial_config_simpleapi.h
+++ /dev/null
@@ -1,5 +0,0 @@
-#pragma once
-
-#undef SERIAL_USE_MULTI_TRANSACTION
-#define SERIAL_SLAVE_BUFFER_LENGTH MATRIX_ROWS/2
-#define SERIAL_MASTER_BUFFER_LENGTH MATRIX_ROWS/2
diff --git a/keyboards/crkbd/rev1/split_util.h b/keyboards/crkbd/rev1/split_util.h
deleted file mode 100644
index 687ca19bd3..0000000000
--- a/keyboards/crkbd/rev1/split_util.h
+++ /dev/null
@@ -1,19 +0,0 @@
-#ifndef SPLIT_KEYBOARD_UTIL_H
-#define SPLIT_KEYBOARD_UTIL_H
-
-#include <stdbool.h>
-#include "eeconfig.h"
-
-#define SLAVE_I2C_ADDRESS           0x32
-
-extern volatile bool isLeftHand;
-
-// slave version of matix scan, defined in matrix.c
-void matrix_slave_scan(void);
-
-void split_keyboard_setup(void);
-bool has_usb(void);
-
-void matrix_master_OLED_init (void);
-
-#endif
diff --git a/keyboards/crkbd/rev1/ssd1306.h b/keyboards/crkbd/rev1/ssd1306.h
new file mode 100644
index 0000000000..11a3cc67f4
--- /dev/null
+++ b/keyboards/crkbd/rev1/ssd1306.h
@@ -0,0 +1,90 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stdio.h>
+#include "action.h"
+
+enum ssd1306_cmds {
+  DisplayOff = 0xAE,
+  DisplayOn = 0xAF,
+
+  SetContrast = 0x81,
+  DisplayAllOnResume = 0xA4,
+
+  DisplayAllOn = 0xA5,
+  NormalDisplay = 0xA6,
+  InvertDisplay = 0xA7,
+  SetDisplayOffset = 0xD3,
+  SetComPins = 0xda,
+  SetVComDetect = 0xdb,
+  SetDisplayClockDiv = 0xD5,
+  SetPreCharge = 0xd9,
+  SetMultiPlex = 0xa8,
+  SetLowColumn = 0x00,
+  SetHighColumn = 0x10,
+  SetStartLine = 0x40,
+
+  SetMemoryMode = 0x20,
+  ColumnAddr = 0x21,
+  PageAddr = 0x22,
+
+  ComScanInc = 0xc0,
+  ComScanDec = 0xc8,
+  SegRemap = 0xa0,
+  SetChargePump = 0x8d,
+  ExternalVcc = 0x01,
+  SwitchCapVcc = 0x02,
+
+  ActivateScroll = 0x2f,
+  DeActivateScroll = 0x2e,
+  SetVerticalScrollArea = 0xa3,
+  RightHorizontalScroll = 0x26,
+  LeftHorizontalScroll = 0x27,
+  VerticalAndRightHorizontalScroll = 0x29,
+  VerticalAndLeftHorizontalScroll = 0x2a,
+};
+
+// Controls the SSD1306 128x32 OLED display via i2c
+
+#ifndef SSD1306_ADDRESS
+#define SSD1306_ADDRESS 0x3C
+#endif
+
+#define DisplayHeight 32
+#define DisplayWidth 128
+
+#define FontHeight 8
+#define FontWidth 6
+
+#define MatrixRows (DisplayHeight / FontHeight)
+#define MatrixCols (DisplayWidth / FontWidth)
+
+struct CharacterMatrix {
+  uint8_t display[MatrixRows][MatrixCols];
+  uint8_t *cursor;
+  bool dirty;
+};
+
+extern struct CharacterMatrix display;
+
+bool iota_gfx_init(bool rotate);
+void iota_gfx_task(void);
+bool iota_gfx_off(void);
+bool iota_gfx_on(void);
+void iota_gfx_flush(void);
+void iota_gfx_write_char(uint8_t c);
+void iota_gfx_write(const char *data);
+void iota_gfx_write_P(const char *data);
+void iota_gfx_clear_screen(void);
+
+void iota_gfx_task_user(void);
+
+void matrix_clear(struct CharacterMatrix *matrix);
+void matrix_write_char_inner(struct CharacterMatrix *matrix, uint8_t c);
+void matrix_write_char(struct CharacterMatrix *matrix, uint8_t c);
+void matrix_write(struct CharacterMatrix *matrix, const char *data);
+void matrix_write_ln(struct CharacterMatrix *matrix, const char *data);
+void matrix_write_P(struct CharacterMatrix *matrix, const char *data);
+void matrix_render(struct CharacterMatrix *matrix);
+
+bool process_record_gfx(uint16_t keycode, keyrecord_t *record);