2 files changed, 92 insertions, 0 deletions
diff --git a/keyboards/crkbd/rev1/legacy/legacy.h b/keyboards/crkbd/rev1/legacy/legacy.h
index 6c6308e592..08dfcefbc1 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/legacy/ssd1306.h b/keyboards/crkbd/rev1/legacy/ssd1306.h
new file mode 100644
index 0000000000..11a3cc67f4
--- /dev/null
+++ b/keyboards/crkbd/rev1/legacy/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);