diff --git a/keyboards/crkbd/keymaps/default/config.h b/keyboards/crkbd/keymaps/default/config.h
index 899fde008de..937d67e25f3 100644
--- a/keyboards/crkbd/keymaps/default/config.h
+++ b/keyboards/crkbd/keymaps/default/config.h
@@ -28,8 +28,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // #define MASTER_RIGHT
 // #define EE_HANDS
 
-#define SSD1306OLED
-
 #define USE_SERIAL_PD2
 
 #define TAPPING_FORCE_HOLD
@@ -44,3 +42,5 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
     #define RGBLIGHT_SAT_STEP 17
     #define RGBLIGHT_VAL_STEP 17
 #endif
+
+#define OLED_FONT_H "keyboards/crkbd/lib/glcdfont.c"
\ No newline at end of file
diff --git a/keyboards/crkbd/keymaps/default/keymap.c b/keyboards/crkbd/keymaps/default/keymap.c
index a3a9d953510..27e3c840611 100644
--- a/keyboards/crkbd/keymaps/default/keymap.c
+++ b/keyboards/crkbd/keymaps/default/keymap.c
@@ -18,218 +18,157 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include QMK_KEYBOARD_H
 
-
-#ifdef RGBLIGHT_ENABLE
-//Following line allows macro to read current RGB settings
-extern rgblight_config_t rgblight_config;
-#endif
-
-extern uint8_t is_master;
-
-// Each layer gets a name for readability, which is then used in the keymap matrix below.
-// The underscores don't mean anything - you can have a layer called STUFF or any other name.
-// Layer names don't all need to be of the same length, obviously, and you can also skip them
-// entirely and just use numbers.
-#define _QWERTY 0
-#define _LOWER 1
-#define _RAISE 2
-#define _ADJUST 3
-
-enum custom_keycodes {
-  QWERTY = SAFE_RANGE,
-  LOWER,
-  RAISE,
-  ADJUST,
-  BACKLIT,
-  RGBRST
-};
-
-enum macro_keycodes {
-  KC_SAMPLEMACRO,
-};
-
 const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
-  [_QWERTY] = LAYOUT_split_3x6_3( \
+  [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_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_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_RSFT,\
+      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,   LOWER,  KC_SPC,     KC_ENT,  RAISE,  KC_RALT \
+                                          KC_LGUI,   MO(1),  KC_SPC,     KC_ENT,   MO(2), KC_RALT
                                       //`--------------------------'  `--------------------------'
 
   ),
 
-  [_LOWER] = LAYOUT_split_3x6_3( \
+  [1] = LAYOUT_split_3x6_3(
   //,-----------------------------------------------------.                    ,-----------------------------------------------------.
-       KC_ESC,    KC_1,    KC_2,    KC_3,    KC_4,    KC_5,                         KC_6,    KC_7,    KC_8,    KC_9,    KC_0, KC_BSPC,\
+       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_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_LSFT, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
   //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
-                                          KC_LGUI,   LOWER,  KC_SPC,     KC_ENT,   RAISE, KC_RALT \
+                                          KC_LGUI, _______,  KC_SPC,     KC_ENT,   MO(3), KC_RALT
                                       //`--------------------------'  `--------------------------'
-    ),
+  ),
 
-  [_RAISE] = LAYOUT_split_3x6_3( \
+  [2] = LAYOUT_split_3x6_3(
   //,-----------------------------------------------------.                    ,-----------------------------------------------------.
-       KC_ESC, KC_EXLM,   KC_AT, KC_HASH,  KC_DLR, KC_PERC,                      KC_CIRC, KC_AMPR, KC_ASTR, KC_LPRN, KC_RPRN, KC_BSPC,\
+       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_LCBR, KC_RCBR, KC_PIPE,  KC_GRV,\
+      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_LBRC, KC_RBRC, KC_BSLS, KC_TILD,\
+      KC_LSFT, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      KC_UNDS, KC_PLUS, KC_LCBR, KC_RCBR, KC_PIPE, KC_TILD,
   //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
-                                          KC_LGUI,   LOWER,  KC_SPC,     KC_ENT,   RAISE, KC_RALT \
+                                          KC_LGUI,   MO(3),  KC_SPC,     KC_ENT, _______, KC_RALT
                                       //`--------------------------'  `--------------------------'
   ),
 
-  [_ADJUST] = LAYOUT_split_3x6_3( \
+  [3] = LAYOUT_split_3x6_3(
   //,-----------------------------------------------------.                    ,-----------------------------------------------------.
-        RESET,  RGBRST, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,\
+        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_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,\
+      RGB_MOD, RGB_HUD, RGB_SAD, RGB_VAD, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
   //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
-                                          KC_LGUI,   LOWER,  KC_SPC,     KC_ENT,   RAISE, KC_RALT \
+                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT
                                       //`--------------------------'  `--------------------------'
   )
 };
 
-int RGB_current_mode;
-
-void persistent_default_layer_set(uint16_t default_layer) {
-  eeconfig_update_default_layer(default_layer);
-  default_layer_set(default_layer);
-}
-
-// Setting ADJUST layer RGB back to default
-void update_tri_layer_RGB(uint8_t layer1, uint8_t layer2, uint8_t layer3) {
-  if (IS_LAYER_ON(layer1) && IS_LAYER_ON(layer2)) {
-    layer_on(layer3);
-  } else {
-    layer_off(layer3);
+#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;
 }
 
-void matrix_init_user(void) {
-    #ifdef RGBLIGHT_ENABLE
-      RGB_current_mode = rgblight_config.mode;
-    #endif
-    //SSD1306 OLED init, make sure to add #define SSD1306OLED in config.h
-    #ifdef SSD1306OLED
-        iota_gfx_init(!has_usb());   // turns on the display
-    #endif
+#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(PSTR("Layer: "), false);
+    switch (layer_state) {
+        case L_BASE:
+            oled_write_ln_P(PSTR("Default"), false);
+            break;
+        case L_LOWER:
+            oled_write_ln_P(PSTR("Lower"), false);
+            break;
+        case L_RAISE:
+            oled_write_ln_P(PSTR("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(PSTR("Adjust"), false);
+            break;
+    }
 }
 
-//SSD1306 OLED update loop, make sure to add #define SSD1306OLED in config.h
-#ifdef SSD1306OLED
 
-// When add source files to SRC in rules.mk, you can use functions.
-const char *read_layer_state(void);
-const char *read_logo(void);
-void set_keylog(uint16_t keycode, keyrecord_t *record);
-const char *read_keylog(void);
-const char *read_keylogs(void);
+char keylog_str[24] = {};
 
-// const char *read_mode_icon(bool swap);
-// const char *read_host_led_state(void);
-// void set_timelog(void);
-// const char *read_timelog(void);
+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 matrix_scan_user(void) {
-   iota_gfx_task();
+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);
 }
 
-void matrix_render_user(struct CharacterMatrix *matrix) {
-  if (is_master) {
-    // If you want to change the display of OLED, you need to change here
-    matrix_write_ln(matrix, read_layer_state());
-    matrix_write_ln(matrix, read_keylog());
-    //matrix_write_ln(matrix, read_keylogs());
-    //matrix_write_ln(matrix, read_mode_icon(keymap_config.swap_lalt_lgui));
-    //matrix_write_ln(matrix, read_host_led_state());
-    //matrix_write_ln(matrix, read_timelog());
-  } else {
-    matrix_write(matrix, read_logo());
-  }
+void oled_render_keylog(void) {
+    oled_write(keylog_str, false);
 }
 
-void matrix_update(struct CharacterMatrix *dest, const struct CharacterMatrix *source) {
-  if (memcmp(dest->display, source->display, sizeof(dest->display))) {
-    memcpy(dest->display, source->display, sizeof(dest->display));
-    dest->dirty = true;
-  }
+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 iota_gfx_task_user(void) {
-  struct CharacterMatrix matrix;
-  matrix_clear(&matrix);
-  matrix_render_user(&matrix);
-  matrix_update(&display, &matrix);
+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();
+    } else {
+        oled_render_logo();
+    }
 }
-#endif//SSD1306OLED
 
 bool process_record_user(uint16_t keycode, keyrecord_t *record) {
   if (record->event.pressed) {
-#ifdef SSD1306OLED
     set_keylog(keycode, record);
-#endif
-    // set_timelog();
-  }
-
-  switch (keycode) {
-    case QWERTY:
-      if (record->event.pressed) {
-        persistent_default_layer_set(1UL<<_QWERTY);
-      }
-      return false;
-    case LOWER:
-      if (record->event.pressed) {
-        layer_on(_LOWER);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      } else {
-        layer_off(_LOWER);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      }
-      return false;
-    case RAISE:
-      if (record->event.pressed) {
-        layer_on(_RAISE);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      } else {
-        layer_off(_RAISE);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      }
-      return false;
-    case ADJUST:
-        if (record->event.pressed) {
-          layer_on(_ADJUST);
-        } else {
-          layer_off(_ADJUST);
-        }
-        return false;
-    case RGB_MOD:
-      #ifdef RGBLIGHT_ENABLE
-        if (record->event.pressed) {
-          rgblight_mode(RGB_current_mode);
-          rgblight_step();
-          RGB_current_mode = rgblight_config.mode;
-        }
-      #endif
-      return false;
-    case RGBRST:
-      #ifdef RGBLIGHT_ENABLE
-        if (record->event.pressed) {
-          eeconfig_update_rgblight_default();
-          rgblight_enable();
-          RGB_current_mode = rgblight_config.mode;
-        }
-      #endif
-      break;
   }
   return true;
 }
+#endif // OLED_DRIVER_ENABLE
diff --git a/keyboards/crkbd/keymaps/default/rules.mk b/keyboards/crkbd/keymaps/default/rules.mk
index f84e5b2af86..9444b88d51a 100644
--- a/keyboards/crkbd/keymaps/default/rules.mk
+++ b/keyboards/crkbd/keymaps/default/rules.mk
@@ -1,10 +1 @@
-
-# If you want to change the display of OLED, you need to change here
-SRC +=  ./lib/glcdfont.c \
-        ./lib/rgb_state_reader.c \
-        ./lib/layer_state_reader.c \
-        ./lib/logo_reader.c \
-        ./lib/keylogger.c \
-        # ./lib/mode_icon_reader.c \
-        # ./lib/host_led_state_reader.c \
-        # ./lib/timelogger.c \
+OLED_DRIVER_ENABLE  = yes
diff --git a/keyboards/crkbd/keymaps/foostan/config.h b/keyboards/crkbd/keymaps/foostan/config.h
deleted file mode 100644
index 644e8136509..00000000000
--- a/keyboards/crkbd/keymaps/foostan/config.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
-This is the c configuration file for the keymap
-
-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
-
-//#define USE_MATRIX_I2C
-
-/* Select hand configuration */
-
-#define MASTER_LEFT
-// #define MASTER_RIGHT
-// #define EE_HANDS
-
-#define SSD1306OLED
-
-#define USE_SERIAL_PD2
-
-#define TAPPING_FORCE_HOLD
-#define TAPPING_TERM 100
-
-#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
diff --git a/keyboards/crkbd/keymaps/foostan/keymap.c b/keyboards/crkbd/keymaps/foostan/keymap.c
deleted file mode 100644
index 5235b783637..00000000000
--- a/keyboards/crkbd/keymaps/foostan/keymap.c
+++ /dev/null
@@ -1,241 +0,0 @@
-#include QMK_KEYBOARD_H
-#ifdef PROTOCOL_LUFA
-  #include "lufa.h"
-  #include "split_util.h"
-#endif
-#ifdef SSD1306OLED
-  #include "ssd1306.h"
-#endif
-
-extern keymap_config_t keymap_config;
-
-#ifdef RGBLIGHT_ENABLE
-//Following line allows macro to read current RGB settings
-extern rgblight_config_t rgblight_config;
-#endif
-
-extern uint8_t is_master;
-
-// Each layer gets a name for readability, which is then used in the keymap matrix below.
-// The underscores don't mean anything - you can have a layer called STUFF or any other name.
-// Layer names don't all need to be of the same length, obviously, and you can also skip them
-// entirely and just use numbers.
-#define _QWERTY 0
-#define _LOWER 1
-#define _RAISE 2
-#define _ADJUST 3
-
-enum custom_keycodes {
-  QWERTY = SAFE_RANGE,
-  LOWER,
-  RAISE,
-  ADJUST,
-  BACKLIT,
-  RGBRST
-};
-
-enum macro_keycodes {
-  KC_SAMPLEMACRO,
-};
-
-#define KC______ KC_TRNS
-#define KC_XXXXX KC_NO
-#define KC_LOWER LOWER
-#define KC_RAISE RAISE
-#define KC_RST   RESET
-#define KC_LRST  RGBRST
-#define KC_LTOG  RGB_TOG
-#define KC_LHUI  RGB_HUI
-#define KC_LHUD  RGB_HUD
-#define KC_LSAI  RGB_SAI
-#define KC_LSAD  RGB_SAD
-#define KC_LVAI  RGB_VAI
-#define KC_LVAD  RGB_VAD
-#define KC_LMOD  RGB_MOD
-#define KC_GUIEI GUI_T(KC_LANG2)
-#define KC_ALTKN ALT_T(KC_LANG1)
-
-const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
-  [_QWERTY] = LAYOUT_kc( \
-  //,-----------------------------------------.                ,-----------------------------------------.
-        TAB,     Q,     W,     E,     R,     T,                      Y,     U,     I,     O,     P,  BSPC,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LCTL,     A,     S,     D,     F,     G,                      H,     J,     K,     L,  SCLN,  QUOT,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LSFT,     Z,     X,     C,     V,     B,                      N,     M,  COMM,   DOT,  SLSH,   ESC,\
-  //|------+------+------+------+------+------+------|  |------+------+------+------+------+------+------|
-                                  GUIEI, LOWER,   SPC,      ENT, RAISE, ALTKN \
-                              //`--------------------'  `--------------------'
-  ),
-
-  [_LOWER] = LAYOUT_kc( \
-  //,-----------------------------------------.                ,-----------------------------------------.
-        TAB,     1,     2,     3,     4,     5,                      6,     7,     8,     9,     0,  BSPC,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LCTL,    F1,    F2,    F3,    F4,    F5,                   LEFT,  DOWN,    UP, RIGHT, XXXXX, XXXXX,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LSFT,    F6,    F7,    F8,    F9,   F10,                  XXXXX, XXXXX, XXXXX, XXXXX, XXXXX, XXXXX,\
-  //|------+------+------+------+------+------+------|  |------+------+------+------+------+------+------|
-                                  GUIEI, LOWER,   SPC,      ENT, RAISE, ALTKN \
-                              //`--------------------'  `--------------------'
-  ),
-
-  [_RAISE] = LAYOUT_kc( \
-  //,-----------------------------------------.                ,-----------------------------------------.
-        TAB,  EXLM,    AT,  HASH,   DLR,  PERC,                   CIRC,  AMPR,  ASTR,  LPRN,  RPRN,  BSPC,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LCTL, XXXXX, XXXXX, XXXXX, XXXXX, XXXXX,                   MINS,   EQL,  LCBR,  RCBR,  PIPE,   GRV,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LSFT, XXXXX, XXXXX, XXXXX, XXXXX, XXXXX,                   UNDS,  PLUS,  LBRC,  RBRC,  BSLS,  TILD,\
-  //|------+------+------+------+------+------+------|  |------+------+------+------+------+------+------|
-                                  GUIEI, LOWER,   SPC,      ENT, RAISE, ALTKN \
-                              //`--------------------'  `--------------------'
-  ),
-
-  [_ADJUST] = LAYOUT_kc( \
-  //,-----------------------------------------.                ,-----------------------------------------.
-        RST,  LRST, XXXXX, XXXXX, XXXXX, XXXXX,                  XXXXX, XXXXX, XXXXX, XXXXX, XXXXX, XXXXX,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LTOG,  LHUI,  LSAI,  LVAI, XXXXX, XXXXX,                  XXXXX, XXXXX, XXXXX, XXXXX, XXXXX, XXXXX,\
-  //|------+------+------+------+------+------|                |------+------+------+------+------+------|
-       LMOD,  LHUD,  LSAD,  LVAD, XXXXX, XXXXX,                  XXXXX, XXXXX, XXXXX, XXXXX, XXXXX, XXXXX,\
-  //|------+------+------+------+------+------+------|  |------+------+------+------+------+------+------|
-                                  GUIEI, LOWER,   SPC,      ENT, RAISE, ALTKN \
-                              //`--------------------'  `--------------------'
-  )
-};
-
-int RGB_current_mode;
-
-void persistent_default_layer_set(uint16_t default_layer) {
-  eeconfig_update_default_layer(default_layer);
-  default_layer_set(default_layer);
-}
-
-// Setting ADJUST layer RGB back to default
-void update_tri_layer_RGB(uint8_t layer1, uint8_t layer2, uint8_t layer3) {
-  if (IS_LAYER_ON(layer1) && IS_LAYER_ON(layer2)) {
-    layer_on(layer3);
-  } else {
-    layer_off(layer3);
-  }
-}
-
-void matrix_init_user(void) {
-    #ifdef RGBLIGHT_ENABLE
-      RGB_current_mode = rgblight_config.mode;
-    #endif
-    //SSD1306 OLED init, make sure to add #define SSD1306OLED in config.h
-    #ifdef SSD1306OLED
-        iota_gfx_init(!has_usb());   // turns on the display
-    #endif
-}
-
-//SSD1306 OLED update loop, make sure to add #define SSD1306OLED in config.h
-#ifdef SSD1306OLED
-
-// When add source files to SRC in rules.mk, you can use functions.
-const char *read_layer_state(void);
-const char *read_logo(void);
-void set_keylog(uint16_t keycode, keyrecord_t *record);
-const char *read_keylog(void);
-const char *read_keylogs(void);
-
-// const char *read_mode_icon(bool swap);
-// const char *read_host_led_state(void);
-// void set_timelog(void);
-// const char *read_timelog(void);
-
-void matrix_scan_user(void) {
-   iota_gfx_task();
-}
-
-void matrix_render_user(struct CharacterMatrix *matrix) {
-  if (is_master) {
-    // If you want to change the display of OLED, you need to change here
-    matrix_write_ln(matrix, read_layer_state());
-    matrix_write_ln(matrix, read_keylog());
-    matrix_write_ln(matrix, read_keylogs());
-    //matrix_write_ln(matrix, read_mode_icon(keymap_config.swap_lalt_lgui));
-    //matrix_write_ln(matrix, read_host_led_state());
-    //matrix_write_ln(matrix, read_timelog());
-  } else {
-    matrix_write(matrix, read_logo());
-  }
-}
-
-void matrix_update(struct CharacterMatrix *dest, const struct CharacterMatrix *source) {
-  if (memcmp(dest->display, source->display, sizeof(dest->display))) {
-    memcpy(dest->display, source->display, sizeof(dest->display));
-    dest->dirty = true;
-  }
-}
-
-void iota_gfx_task_user(void) {
-  struct CharacterMatrix matrix;
-  matrix_clear(&matrix);
-  matrix_render_user(&matrix);
-  matrix_update(&display, &matrix);
-}
-#endif//SSD1306OLED
-
-bool process_record_user(uint16_t keycode, keyrecord_t *record) {
-  if (record->event.pressed) {
-#ifdef SSD1306OLED
-    set_keylog(keycode, record);
-#endif
-    // set_timelog();
-  }
-
-  switch (keycode) {
-    case QWERTY:
-      if (record->event.pressed) {
-        persistent_default_layer_set(1UL<<_QWERTY);
-      }
-      return false;
-    case LOWER:
-      if (record->event.pressed) {
-        layer_on(_LOWER);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      } else {
-        layer_off(_LOWER);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      }
-      return false;
-    case RAISE:
-      if (record->event.pressed) {
-        layer_on(_RAISE);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      } else {
-        layer_off(_RAISE);
-        update_tri_layer_RGB(_LOWER, _RAISE, _ADJUST);
-      }
-      return false;
-    case ADJUST:
-        if (record->event.pressed) {
-          layer_on(_ADJUST);
-        } else {
-          layer_off(_ADJUST);
-        }
-        return false;
-    case RGB_MOD:
-      #ifdef RGBLIGHT_ENABLE
-        if (record->event.pressed) {
-          rgblight_mode(RGB_current_mode);
-          rgblight_step();
-          RGB_current_mode = rgblight_config.mode;
-        }
-      #endif
-      return false;
-    case RGBRST:
-      #ifdef RGBLIGHT_ENABLE
-        if (record->event.pressed) {
-          eeconfig_update_rgblight_default();
-          rgblight_enable();
-          RGB_current_mode = rgblight_config.mode;
-        }
-      #endif
-      break;
-  }
-  return true;
-}
diff --git a/keyboards/crkbd/keymaps/foostan/rules.mk b/keyboards/crkbd/keymaps/foostan/rules.mk
deleted file mode 100644
index f84e5b2af86..00000000000
--- a/keyboards/crkbd/keymaps/foostan/rules.mk
+++ /dev/null
@@ -1,10 +0,0 @@
-
-# If you want to change the display of OLED, you need to change here
-SRC +=  ./lib/glcdfont.c \
-        ./lib/rgb_state_reader.c \
-        ./lib/layer_state_reader.c \
-        ./lib/logo_reader.c \
-        ./lib/keylogger.c \
-        # ./lib/mode_icon_reader.c \
-        # ./lib/host_led_state_reader.c \
-        # ./lib/timelogger.c \
diff --git a/keyboards/crkbd/rev1/common/common.c b/keyboards/crkbd/rev1/common/common.c
index 5ea7347de88..ddc0b5fe91d 100644
--- a/keyboards/crkbd/rev1/common/common.c
+++ b/keyboards/crkbd/rev1/common/common.c
@@ -17,5 +17,3 @@ 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
index af1795f4808..71779e2e0f3 100644
--- a/keyboards/crkbd/rev1/common/common.h
+++ b/keyboards/crkbd/rev1/common/common.h
@@ -21,4 +21,4 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "rev1.h"
 
 #define has_usb() is_keyboard_master()
-extern uint8_t is_master;
+#define is_master is_keyboard_master()
diff --git a/keyboards/crkbd/rev1/common/keymaps/via/keymap.c b/keyboards/crkbd/rev1/common/keymaps/via/keymap.c
index a3b2e52ce55..ecd1f17a5c7 100644
--- a/keyboards/crkbd/rev1/common/keymaps/via/keymap.c
+++ b/keyboards/crkbd/rev1/common/keymaps/via/keymap.c
@@ -19,7 +19,7 @@ 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( \
+  [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,
   //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
@@ -32,7 +32,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
 
   ),
 
-  [1] = LAYOUT_split_3x6_3( \
+  [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,
   //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
@@ -40,11 +40,11 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
   //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
       KC_LSFT, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
   //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
-                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT\
+                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT
                                       //`--------------------------'  `--------------------------'
   ),
 
-  [2] = LAYOUT_split_3x6_3( \
+  [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,
   //|--------+--------+--------+--------+--------+--------|                    |--------+--------+--------+--------+--------+--------|
@@ -56,15 +56,15 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
                                       //`--------------------------'  `--------------------------'
   ),
 
-  [3] = LAYOUT_split_3x6_3( \
+  [3] = LAYOUT_split_3x6_3(
   //,-----------------------------------------------------.                    ,-----------------------------------------------------.
-        RESET, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,\
+        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_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,\
+      RGB_MOD, RGB_HUD, RGB_SAD, RGB_VAD, XXXXXXX, XXXXXXX,                      XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
   //|--------+--------+--------+--------+--------+--------+--------|  |--------+--------+--------+--------+--------+--------+--------|
-                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT\
+                                          KC_LGUI, _______,  KC_SPC,     KC_ENT, _______, KC_RALT
                                       //`--------------------------'  `--------------------------'
   )
 };
@@ -83,30 +83,28 @@ oled_rotation_t oled_init_user(oled_rotation_t rotation) {
 #define L_ADJUST 8
 
 void oled_render_layer_state(void) {
-    oled_write_P("Layer: ", false);
+    oled_write_P(PSTR("Layer: "), false);
     switch (layer_state) {
         case L_BASE:
-            oled_write_ln_P("Default", false);
+            oled_write_ln_P(PSTR("Default"), false);
             break;
         case L_LOWER:
-            oled_write_ln_P("Lower", false);
+            oled_write_ln_P(PSTR("Lower"), false);
             break;
         case L_RAISE:
-            oled_write_ln_P("Raise", false);
+            oled_write_ln_P(PSTR("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);
+            oled_write_ln_P(PSTR("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',
@@ -128,25 +126,11 @@ void set_keylog(uint16_t keycode, keyrecord_t *record) {
   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 */
@@ -176,8 +160,6 @@ 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();
     }
@@ -186,7 +168,6 @@ void oled_task_user(void) {
 bool process_record_user(uint16_t keycode, keyrecord_t *record) {
   if (record->event.pressed) {
     set_keylog(keycode, record);
-    // set_timelog();
   }
   return true;
 }
diff --git a/keyboards/crkbd/rev1/common/ssd1306.c b/keyboards/crkbd/rev1/common/ssd1306.c
deleted file mode 100644
index 4a889da6738..00000000000
--- a/keyboards/crkbd/rev1/common/ssd1306.c
+++ /dev/null
@@ -1,360 +0,0 @@
-#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/legacy/legacy.h b/keyboards/crkbd/rev1/legacy/legacy.h
index 6c6308e592c..08dfcefbc10 100644
--- a/keyboards/crkbd/rev1/legacy/legacy.h
+++ b/keyboards/crkbd/rev1/legacy/legacy.h
@@ -19,3 +19,5 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #pragma once
 
 #include "rev1.h"
+
+extern uint8_t is_master;
\ No newline at end of file
diff --git a/keyboards/crkbd/rev1/ssd1306.h b/keyboards/crkbd/rev1/legacy/ssd1306.h
similarity index 100%
rename from keyboards/crkbd/rev1/ssd1306.h
rename to keyboards/crkbd/rev1/legacy/ssd1306.h
diff --git a/keyboards/crkbd/rev1/rev1.c b/keyboards/crkbd/rev1/rev1.c
index 5e4e6560f00..f2df8942abd 100644
--- a/keyboards/crkbd/rev1/rev1.c
+++ b/keyboards/crkbd/rev1/rev1.c
@@ -87,10 +87,6 @@ led_config_t g_led_config = { {
 
 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){ {
diff --git a/keyboards/crkbd/rev1/rev1.h b/keyboards/crkbd/rev1/rev1.h
index ce88068e64a..c805efccceb 100644
--- a/keyboards/crkbd/rev1/rev1.h
+++ b/keyboards/crkbd/rev1/rev1.h
@@ -18,8 +18,6 @@ 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"
diff --git a/layouts/community/split_3x6_3/drashna/keymap.c b/layouts/community/split_3x6_3/drashna/keymap.c
index 30e3958febc..e53d0539738 100644
--- a/layouts/community/split_3x6_3/drashna/keymap.c
+++ b/layouts/community/split_3x6_3/drashna/keymap.c
@@ -16,8 +16,6 @@
 
 #include "drashna.h"
 
-extern uint8_t is_master;
-
 #ifdef RGBLIGHT_ENABLE
 // Following line allows macro to read current RGB settings
 extern rgblight_config_t rgblight_config;