[Keyboard] add claw44 keyboard (#5511)

* add claw44 keyboard

* Update keyboards/claw44/lib/layer_state_reader.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Update keyboards/claw44/lib/layer_state_reader.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Update keyboards/claw44/lib/layer_state_reader.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Update keyboards/claw44/lib/layer_state_reader.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Update keyboards/claw44/readme.md

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Remove unnecessary code because of default value

* Move layer definition

* Update keyboards/claw44/keymaps/default/keymap.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Update keyboards/claw44/keymaps/yfuku/keymap.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Update keyboards/claw44/readme.md

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* default keymap. LAYOUT_kc -> LAYOUT macro

* Move rules.mk from keymaps to keyboard level.

* add Hardware Supported, Hardware Availability

* Update keyboards/claw44/keymaps/default/keymap.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Update keyboards/claw44/keymaps/yfuku/keymap.c

Co-Authored-By: yfuku <30647434+yfuku@users.noreply.github.com>

* Remove depreciated function

10 files changed, 737 insertions, 0 deletions

diff --git a/keyboards/claw44/rev1/config.h b/keyboards/claw44/rev1/config.h
new file mode 100644
index 000000000..ba2ed4559
--- /dev/null
+++ b/keyboards/claw44/rev1/config.h
@@ -0,0 +1,76 @@
+/*
+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
+
+/* USB Device descriptor parameter */
+#define VENDOR_ID       0xFEED
+#define PRODUCT_ID      0x3060
+#define DEVICE_VER      0x0001
+#define MANUFACTURER    yfuku
+#define PRODUCT         claw44
+#define DESCRIPTION     A split keyboard with 3x6 vertically staggered keys and 4 thumb keys
+
+/* key matrix size */
+// Rows are doubled-up
+#define MATRIX_ROWS 8
+#define MATRIX_COLS 7
+#define MATRIX_ROW_PINS { D4, C6, D7, E6 }
+
+// wiring of each half
+#define MATRIX_COL_PINS { F4, F5, F6, F7, B1, B3, B2 }
+// #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 DEBOUNCING_DELAY 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
+
+#define RGBLED_NUM 12    // Number of LEDs
+*/
+
+/*
+ * 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/claw44/rev1/matrix.c b/keyboards/claw44/rev1/matrix.c
new file mode 100644
index 000000000..718cc5744
--- /dev/null
+++ b/keyboards/claw44/rev1/matrix.c
@@ -0,0 +1,357 @@
+/*
+Copyright 2012 Jun Wako <wakojun@gmail.com>
+
+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/>.
+*/
+
+/*
+ * scan matrix
+ */
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <avr/io.h>
+#include <avr/wdt.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include "print.h"
+#include "debug.h"
+#include "util.h"
+#include "matrix.h"
+#include "split_util.h"
+#include "pro_micro.h"
+
+#ifdef USE_MATRIX_I2C
+#  include "i2c.h"
+#else // USE_SERIAL
+#  include "split_scomm.h"
+#endif
+
+#ifndef DEBOUNCE
+#  define DEBOUNCE	5
+#endif
+
+#define ERROR_DISCONNECT_COUNT 5
+
+static uint8_t debouncing = DEBOUNCE;
+static const int ROWS_PER_HAND = MATRIX_ROWS/2;
+static uint8_t error_count = 0;
+uint8_t is_master = 0 ;
+
+static const uint8_t row_pins[MATRIX_ROWS] = MATRIX_ROW_PINS;
+static const uint8_t col_pins[MATRIX_COLS] = MATRIX_COL_PINS;
+
+/* matrix state(1:on, 0:off) */
+static matrix_row_t matrix[MATRIX_ROWS];
+static matrix_row_t matrix_debouncing[MATRIX_ROWS];
+
+static matrix_row_t read_cols(void);
+static void init_cols(void);
+static void unselect_rows(void);
+static void select_row(uint8_t row);
+static uint8_t matrix_master_scan(void);
+
+
+__attribute__ ((weak))
+void matrix_init_kb(void) {
+    matrix_init_user();
+}
+
+__attribute__ ((weak))
+void matrix_scan_kb(void) {
+    matrix_scan_user();
+}
+
+__attribute__ ((weak))
+void matrix_init_user(void) {
+}
+
+__attribute__ ((weak))
+void matrix_scan_user(void) {
+}
+
+inline
+uint8_t matrix_rows(void)
+{
+    return MATRIX_ROWS;
+}
+
+inline
+uint8_t matrix_cols(void)
+{
+    return MATRIX_COLS;
+}
+
+void matrix_init(void)
+{
+    debug_enable = true;
+    debug_matrix = true;
+    debug_mouse = true;
+    // initialize row and col
+    unselect_rows();
+    init_cols();
+
+    TX_RX_LED_INIT;
+    TXLED0;
+    RXLED0;
+
+    // initialize matrix state: all keys off
+    for (uint8_t i=0; i < MATRIX_ROWS; i++) {
+        matrix[i] = 0;
+        matrix_debouncing[i] = 0;
+    }
+
+    is_master = has_usb();
+
+    matrix_init_quantum();
+}
+
+uint8_t _matrix_scan(void)
+{
+    // Right hand is stored after the left in the matirx so, we need to offset it
+    int offset = isLeftHand ? 0 : (ROWS_PER_HAND);
+
+    for (uint8_t i = 0; i < ROWS_PER_HAND; i++) {
+        select_row(i);
+        _delay_us(30);  // without this wait read unstable value.
+        matrix_row_t cols = read_cols();
+        if (matrix_debouncing[i+offset] != cols) {
+            matrix_debouncing[i+offset] = cols;
+            debouncing = DEBOUNCE;
+        }
+        unselect_rows();
+    }
+
+    if (debouncing) {
+        if (--debouncing) {
+            _delay_ms(1);
+        } else {
+            for (uint8_t i = 0; i < ROWS_PER_HAND; i++) {
+                matrix[i+offset] = matrix_debouncing[i+offset];
+            }
+        }
+    }
+
+    return 1;
+}
+
+#ifdef USE_MATRIX_I2C
+
+// Get rows from other half over i2c
+int i2c_transaction(void) {
+    int slaveOffset = (isLeftHand) ? (ROWS_PER_HAND) : 0;
+
+    int err = i2c_master_start(SLAVE_I2C_ADDRESS + I2C_WRITE);
+    if (err) goto i2c_error;
+
+    // start of matrix stored at 0x00
+    err = i2c_master_write(0x00);
+    if (err) goto i2c_error;
+
+    // Start read
+    err = i2c_master_start(SLAVE_I2C_ADDRESS + I2C_READ);
+    if (err) goto i2c_error;
+
+    if (!err) {
+        int i;
+        for (i = 0; i < ROWS_PER_HAND-1; ++i) {
+            matrix[slaveOffset+i] = i2c_master_read(I2C_ACK);
+        }
+        matrix[slaveOffset+i] = i2c_master_read(I2C_NACK);
+        i2c_master_stop();
+    } else {
+i2c_error: // the cable is disconnceted, or something else went wrong
+        i2c_reset_state();
+        return err;
+    }
+
+    return 0;
+}
+
+#else // USE_SERIAL
+
+int serial_transaction(int master_changed) {
+    int slaveOffset = (isLeftHand) ? (ROWS_PER_HAND) : 0;
+#ifdef SERIAL_USE_MULTI_TRANSACTION
+    int ret=serial_update_buffers(master_changed);
+#else
+    int ret=serial_update_buffers();
+#endif
+    if (ret ) {
+        if(ret==2) RXLED1;
+        return 1;
+    }
+    RXLED0;
+    memcpy(&matrix[slaveOffset],
+        (void *)serial_slave_buffer, SERIAL_SLAVE_BUFFER_LENGTH);
+    return 0;
+}
+#endif
+
+uint8_t matrix_scan(void)
+{
+    if (is_master) {
+        matrix_master_scan();
+    }else{
+        matrix_slave_scan();
+        int offset = (isLeftHand) ? ROWS_PER_HAND : 0;
+        memcpy(&matrix[offset],
+               (void *)serial_master_buffer, SERIAL_MASTER_BUFFER_LENGTH);
+        matrix_scan_quantum();
+    }
+    return 1;
+}
+
+
+uint8_t matrix_master_scan(void) {
+
+    int ret = _matrix_scan();
+    int mchanged = 1;
+
+    int offset = (isLeftHand) ? 0 : ROWS_PER_HAND;
+
+#ifdef USE_MATRIX_I2C
+//    for (int i = 0; i < ROWS_PER_HAND; ++i) {
+        /* i2c_slave_buffer[i] = matrix[offset+i]; */
+//        i2c_slave_buffer[i] = matrix[offset+i];
+//    }
+#else // USE_SERIAL
+  #ifdef SERIAL_USE_MULTI_TRANSACTION
+    mchanged = memcmp((void *)serial_master_buffer,
+		      &matrix[offset], SERIAL_MASTER_BUFFER_LENGTH);
+  #endif
+    memcpy((void *)serial_master_buffer,
+	   &matrix[offset], SERIAL_MASTER_BUFFER_LENGTH);
+#endif
+
+#ifdef USE_MATRIX_I2C
+    if( i2c_transaction() ) {
+#else // USE_SERIAL
+    if( serial_transaction(mchanged) ) {
+#endif
+        // turn on the indicator led when halves are disconnected
+        TXLED1;
+
+        error_count++;
+
+        if (error_count > ERROR_DISCONNECT_COUNT) {
+            // reset other half if disconnected
+            int slaveOffset = (isLeftHand) ? (ROWS_PER_HAND) : 0;
+            for (int i = 0; i < ROWS_PER_HAND; ++i) {
+                matrix[slaveOffset+i] = 0;
+            }
+        }
+    } else {
+        // turn off the indicator led on no error
+        TXLED0;
+        error_count = 0;
+    }
+    matrix_scan_quantum();
+    return ret;
+}
+
+void matrix_slave_scan(void) {
+    _matrix_scan();
+
+    int offset = (isLeftHand) ? 0 : ROWS_PER_HAND;
+
+#ifdef USE_MATRIX_I2C
+    for (int i = 0; i < ROWS_PER_HAND; ++i) {
+        /* i2c_slave_buffer[i] = matrix[offset+i]; */
+        i2c_slave_buffer[i] = matrix[offset+i];
+    }
+#else // USE_SERIAL
+  #ifdef SERIAL_USE_MULTI_TRANSACTION
+    int change = 0;
+  #endif
+    for (int i = 0; i < ROWS_PER_HAND; ++i) {
+  #ifdef SERIAL_USE_MULTI_TRANSACTION
+        if( serial_slave_buffer[i] != matrix[offset+i] )
+	    change = 1;
+  #endif
+        serial_slave_buffer[i] = matrix[offset+i];
+    }
+  #ifdef SERIAL_USE_MULTI_TRANSACTION
+    slave_buffer_change_count += change;
+  #endif
+#endif
+}
+
+bool matrix_is_modified(void)
+{
+    if (debouncing) return false;
+    return true;
+}
+
+inline
+bool matrix_is_on(uint8_t row, uint8_t col)
+{
+    return (matrix[row] & ((matrix_row_t)1<<col));
+}
+
+inline
+matrix_row_t matrix_get_row(uint8_t row)
+{
+    return matrix[row];
+}
+
+void matrix_print(void)
+{
+    print("\nr/c 0123456789ABCDEF\n");
+    for (uint8_t row = 0; row < MATRIX_ROWS; row++) {
+        phex(row); print(": ");
+        pbin_reverse16(matrix_get_row(row));
+        print("\n");
+    }
+}
+
+uint8_t matrix_key_count(void)
+{
+    uint8_t count = 0;
+    for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
+        count += bitpop16(matrix[i]);
+    }
+    return count;
+}
+
+static void  init_cols(void)
+{
+    for(int x = 0; x < MATRIX_COLS; x++) {
+        _SFR_IO8((col_pins[x] >> 4) + 1) &=  ~_BV(col_pins[x] & 0xF);
+        _SFR_IO8((col_pins[x] >> 4) + 2) |= _BV(col_pins[x] & 0xF);
+    }
+}
+
+static matrix_row_t read_cols(void)
+{
+    matrix_row_t result = 0;
+    for(int x = 0; x < MATRIX_COLS; x++) {
+        result |= (_SFR_IO8(col_pins[x] >> 4) & _BV(col_pins[x] & 0xF)) ? 0 : (1 << x);
+    }
+    return result;
+}
+
+static void unselect_rows(void)
+{
+    for(int x = 0; x < ROWS_PER_HAND; x++) {
+        _SFR_IO8((row_pins[x] >> 4) + 1) &=  ~_BV(row_pins[x] & 0xF);
+        _SFR_IO8((row_pins[x] >> 4) + 2) |= _BV(row_pins[x] & 0xF);
+    }
+}
+
+static void select_row(uint8_t row)
+{
+    _SFR_IO8((row_pins[row] >> 4) + 1) |=  _BV(row_pins[row] & 0xF);
+    _SFR_IO8((row_pins[row] >> 4) + 2) &= ~_BV(row_pins[row] & 0xF);
+}
diff --git a/keyboards/claw44/rev1/rev1.c b/keyboards/claw44/rev1/rev1.c
new file mode 100644
index 000000000..9529636f5
--- /dev/null
+++ b/keyboards/claw44/rev1/rev1.c
@@ -0,0 +1,8 @@
+#include "claw44.h"
+
+#ifdef SSD1306OLED
+void led_set_kb(uint8_t usb_led) {
+  // put your keyboard LED indicator (ex: Caps Lock LED) toggling code here
+  //led_set_user(usb_led);
+}
+#endif
diff --git a/keyboards/claw44/rev1/rev1.h b/keyboards/claw44/rev1/rev1.h
new file mode 100644
index 000000000..f7ec2cbfe
--- /dev/null
+++ b/keyboards/claw44/rev1/rev1.h
@@ -0,0 +1,57 @@
+#pragma once
+
+#include "../claw44.h"
+
+//void promicro_bootloader_jmp(bool program);
+#include "quantum.h"
+
+#ifdef RGBLIGHT_ENABLE
+//rgb led driver
+#include "ws2812.h"
+#endif
+
+#ifdef USE_I2C
+#include <stddef.h>
+#ifdef __AVR__
+	#include <avr/io.h>
+	#include <avr/interrupt.h>
+#endif
+#endif
+
+//void promicro_bootloader_jmp(bool program);
+#define LAYOUT( \
+  L00, L01, L02, L03, L04, L05,           R00, R01, R02, R03, R04, R05, \
+  L10, L11, L12, L13, L14, L15,           R10, R11, R12, R13, R14, R15, \
+  L20, L21, L22, L23, L24, L25,           R20, R21, R22, R23, R24, R25, \
+                 L30, L31, L32, L33, R30, R31, R32, R33 \
+  ) \
+  { \
+    { L00, L01, L02, L03, L04, L05 }, \
+    { L10, L11, L12, L13, L14, L15 }, \
+    { L20, L21, L22, L23, L24, L25 }, \
+    { KC_NO, KC_NO, L30, L31, L32, L33 }, \
+    { R05, R04, R03, R02, R01, R00 }, \
+    { R15, R14, R13, R12, R11, R10 }, \
+    { R25, R24, R23, R22, R21, R20 }, \
+    { KC_NO, KC_NO, R33, R32, R31, R30 } \
+  }
+
+#define LAYOUT_kc( \
+  L00, L01, L02, L03, L04, L05,           R00, R01, R02, R03, R04, R05, \
+  L10, L11, L12, L13, L14, L15,           R10, R11, R12, R13, R14, R15, \
+  L20, L21, L22, L23, L24, L25,           R20, R21, R22, R23, R24, R25, \
+                 L30, L31, L32, L33, R30, R31, R32, R33 \
+  ) \
+  LAYOUT( \
+    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, \
+                                  KC_##L30, KC_##L31, KC_##L32, KC_##L33, KC_##R30, KC_##R31, KC_##R32, KC_##R33 \
+  )
+
+enum layer_number {
+  _QWERTY = 0,
+  _LOWER,
+  _RAISE,
+  _ADJUST,
+};
diff --git a/keyboards/claw44/rev1/rules.mk b/keyboards/claw44/rev1/rules.mk
new file mode 100644
index 000000000..ae95ec401
--- /dev/null
+++ b/keyboards/claw44/rev1/rules.mk
@@ -0,0 +1,31 @@
+SRC += rev1/matrix.c
+SRC += rev1/split_util.c
+SRC += rev1/split_scomm.c
+
+# Build Options
+BOOTMAGIC_ENABLE = no       # Virtual DIP switch configuration(+1000)
+MOUSEKEY_ENABLE = no        # Mouse keys(+4700)
+EXTRAKEY_ENABLE = no        # Audio control and System control(+450)
+CONSOLE_ENABLE = no         # Console for debug(+400)
+COMMAND_ENABLE = no         # Commands for debug and configuration
+NKRO_ENABLE = no            # Nkey Rollover - if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
+BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
+MIDI_ENABLE = no            # MIDI controls
+AUDIO_ENABLE = no           # Audio output on port C6
+UNICODE_ENABLE = no         # Unicode
+BLUETOOTH_ENABLE = no       # Enable Bluetooth with the Adafruit EZ-Key HID
+RGBLIGHT_ENABLE = no       # Enable WS2812 RGB underlight.
+SWAP_HANDS_ENABLE = no      # Enable one-hand typing
+
+# Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
+SLEEP_LED_ENABLE = no    # Breathing sleep LED during USB suspend
+
+# If you want to change the display of OLED, you need to change here
+SRC += ./lib/glcdfont.c \
+       ./lib/layer_state_reader.c \
+       ./lib/logo_reader.c \
+       ./lib/keylogger.c \
+       # ./lib/rgb_state_reader.c \
+       # ./lib/mode_icon_reader.c \
+       # ./lib/host_led_state_reader.c \
+       # ./lib/timelogger.c \
diff --git a/keyboards/claw44/rev1/serial_config.h b/keyboards/claw44/rev1/serial_config.h
new file mode 100644
index 000000000..4fab8e8dd
--- /dev/null
+++ b/keyboards/claw44/rev1/serial_config.h
@@ -0,0 +1,4 @@
+#ifndef SOFT_SERIAL_PIN
+#define SOFT_SERIAL_PIN D2
+#define SERIAL_USE_MULTI_TRANSACTION
+#endif
diff --git a/keyboards/claw44/rev1/split_scomm.c b/keyboards/claw44/rev1/split_scomm.c
new file mode 100644
index 000000000..a1fe6ba5b
--- /dev/null
+++ b/keyboards/claw44/rev1/split_scomm.c
@@ -0,0 +1,91 @@
+#ifdef USE_SERIAL
+#ifdef SERIAL_USE_MULTI_TRANSACTION
+/* --- USE flexible API (using multi-type transaction function) --- */
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <split_scomm.h>
+#include "serial.h"
+#ifdef CONSOLE_ENABLE
+  #include <print.h>
+#endif
+
+uint8_t volatile serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH] = {0};
+uint8_t volatile serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH] = {0};
+uint8_t volatile status_com = 0;
+uint8_t volatile status1 = 0;
+uint8_t slave_buffer_change_count = 0;
+uint8_t s_change_old = 0xff;
+uint8_t s_change_new = 0xff;
+
+SSTD_t transactions[] = {
+#define GET_SLAVE_STATUS 0
+    /* master buffer not changed, only recive slave_buffer_change_count */
+    { (uint8_t *)&status_com,
+      0, NULL,
+      sizeof(slave_buffer_change_count), &slave_buffer_change_count,
+    },
+#define PUT_MASTER_GET_SLAVE_STATUS 1
+    /* master buffer changed need send, and recive slave_buffer_change_count  */
+    { (uint8_t *)&status_com,
+      sizeof(serial_master_buffer), (uint8_t *)serial_master_buffer,
+      sizeof(slave_buffer_change_count), &slave_buffer_change_count,
+    },
+#define GET_SLAVE_BUFFER 2
+    /* recive serial_slave_buffer */
+    { (uint8_t *)&status1,
+      0, NULL,
+      sizeof(serial_slave_buffer), (uint8_t *)serial_slave_buffer
+    }
+};
+
+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 master_update)
+{
+    int status, smatstatus;
+    static int need_retry = 0;
+
+    if( s_change_old != s_change_new ) {
+        smatstatus = soft_serial_transaction(GET_SLAVE_BUFFER);
+        if( smatstatus == TRANSACTION_END ) {
+            s_change_old = s_change_new;
+#ifdef CONSOLE_ENABLE
+            uprintf("slave matrix = %b %b %b %b\n",
+                    serial_slave_buffer[0], serial_slave_buffer[1],
+                    serial_slave_buffer[2], serial_slave_buffer[3]);
+#endif
+        }
+    } else {
+        // serial_slave_buffer dosen't change
+        smatstatus = TRANSACTION_END; // dummy status
+    }
+
+    if( !master_update && !need_retry) {
+        status = soft_serial_transaction(GET_SLAVE_STATUS);
+    } else {
+        status = soft_serial_transaction(PUT_MASTER_GET_SLAVE_STATUS);
+    }
+    if( status == TRANSACTION_END ) {
+        s_change_new = slave_buffer_change_count;
+        need_retry = 0;
+    } else {
+        need_retry = 1;
+    }
+    return smatstatus;
+}
+
+#endif // SERIAL_USE_MULTI_TRANSACTION
+#endif /* USE_SERIAL */
diff --git a/keyboards/claw44/rev1/split_scomm.h b/keyboards/claw44/rev1/split_scomm.h
new file mode 100644
index 000000000..873d8939d
--- /dev/null
+++ b/keyboards/claw44/rev1/split_scomm.h
@@ -0,0 +1,24 @@
+#ifndef SPLIT_COMM_H
+#define SPLIT_COMM_H
+
+#ifndef SERIAL_USE_MULTI_TRANSACTION
+/* --- USE Simple API (OLD API, compatible with let's split serial.c) --- */
+#include "serial.h"
+
+#else
+/* --- USE flexible API (using multi-type transaction function) --- */
+// Buffers for master - slave communication
+#define SERIAL_SLAVE_BUFFER_LENGTH MATRIX_ROWS/2
+#define SERIAL_MASTER_BUFFER_LENGTH MATRIX_ROWS/2
+
+extern volatile uint8_t serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH];
+extern volatile uint8_t serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH];
+extern uint8_t slave_buffer_change_count;
+
+void serial_master_init(void);
+void serial_slave_init(void);
+int serial_update_buffers(int master_changed);
+
+#endif
+
+#endif /* SPLIT_COMM_H */
diff --git a/keyboards/claw44/rev1/split_util.c b/keyboards/claw44/rev1/split_util.c
new file mode 100644
index 000000000..e1ff8b437
--- /dev/null
+++ b/keyboards/claw44/rev1/split_util.c
@@ -0,0 +1,70 @@
+#include <avr/io.h>
+#include <avr/wdt.h>
+#include <avr/power.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <avr/eeprom.h>
+#include "split_util.h"
+#include "matrix.h"
+#include "keyboard.h"
+
+#ifdef USE_MATRIX_I2C
+#  include "i2c.h"
+#else
+#  include "split_scomm.h"
+#endif
+
+volatile bool isLeftHand = true;
+
+static void setup_handedness(void) {
+  #ifdef EE_HANDS
+    isLeftHand = eeprom_read_byte(EECONFIG_HANDEDNESS);
+  #else
+    // I2C_MASTER_RIGHT is deprecated, use MASTER_RIGHT instead, since this works for both serial and i2c
+    #if defined(I2C_MASTER_RIGHT) || defined(MASTER_RIGHT)
+      isLeftHand = !has_usb();
+    #else
+      isLeftHand = has_usb();
+    #endif
+  #endif
+}
+
+static void keyboard_master_setup(void) {
+
+#ifdef USE_MATRIX_I2C
+    i2c_master_init();
+#else
+    serial_master_init();
+#endif
+}
+
+static void keyboard_slave_setup(void) {
+
+#ifdef USE_MATRIX_I2C
+    i2c_slave_init(SLAVE_I2C_ADDRESS);
+#else
+    serial_slave_init();
+#endif
+}
+
+bool has_usb(void) {
+   USBCON |= (1 << OTGPADE); //enables VBUS pad
+   _delay_us(5);
+   return (USBSTA & (1<<VBUS));  //checks state of VBUS
+}
+
+void split_keyboard_setup(void) {
+   setup_handedness();
+
+   if (has_usb()) {
+      keyboard_master_setup();
+   } else {
+      keyboard_slave_setup();
+   }
+   sei();
+}
+
+// this code runs before the usb and keyboard is initialized
+void matrix_setup(void) {
+    split_keyboard_setup();
+}
diff --git a/keyboards/claw44/rev1/split_util.h b/keyboards/claw44/rev1/split_util.h
new file mode 100644
index 000000000..687ca19bd
--- /dev/null
+++ b/keyboards/claw44/rev1/split_util.h
@@ -0,0 +1,19 @@
+#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