Next set of split_common changes (#4974)

* Update split_common to use standard i2c drivers

* Eliminate RGB_DIRTY/BACKLIT_DIRTY

* Fix avr i2c_master error handling

* Fix i2c_slave addressing

* Remove unneeded timeout on i2c_stop()

* Fix RGB I2C transfers

* Remove incorrect comment

24 files changed, 190 insertions, 617 deletions

diff --git a/common_features.mk b/common_features.mk
index 20c38ae82..046f94d1d 100644
--- a/common_features.mk
+++ b/common_features.mk
@@ -308,16 +308,16 @@ ifeq ($(strip $(SPLIT_KEYBOARD)), yes)
     OPT_DEFS += -DSPLIT_KEYBOARD
 
     # Include files used by all split keyboards
-    QUANTUM_SRC += $(QUANTUM_DIR)/split_common/split_flags.c \
-                   $(QUANTUM_DIR)/split_common/split_util.c
+    QUANTUM_SRC += $(QUANTUM_DIR)/split_common/split_util.c
 
     # Determine which (if any) transport files are required
     ifneq ($(strip $(SPLIT_TRANSPORT)), custom)
         QUANTUM_SRC += $(QUANTUM_DIR)/split_common/transport.c
         # Functions added via QUANTUM_LIB_SRC are only included in the final binary if they're called.
-        # Unused functions are pruned away, which is why we can add both drivers here without bloat.
-        QUANTUM_LIB_SRC += $(QUANTUM_DIR)/split_common/i2c.c \
-                           $(QUANTUM_DIR)/split_common/serial.c
+        # Unused functions are pruned away, which is why we can add multiple drivers here without bloat.
+        QUANTUM_LIB_SRC += $(QUANTUM_DIR)/split_common/serial.c \
+                           i2c_master.c \
+                           i2c_slave.c
     endif
     COMMON_VPATH += $(QUANTUM_PATH)/split_common
 endif
diff --git a/docs/i2c_driver.md b/docs/i2c_driver.md
index 18546fc62..bb1a2d74f 100644
--- a/docs/i2c_driver.md
+++ b/docs/i2c_driver.md
@@ -12,7 +12,7 @@ The I2C Master drivers used in QMK have a set of common functions to allow porta
 |`uint8_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout);`                         |Receive data over I2C. Address is the 7-bit slave address without the direction. Saves number of bytes specified by `length` in `data` array. Returns status of transaction. |
 |`uint8_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);`       |Same as the `i2c_transmit` function but `regaddr` sets where in the slave the data will be written.                                                                          |
 |`uint8_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);`        |Same as the `i2c_receive` function but `regaddr` sets from where in the slave the data will be read.                                                                         |
-|`uint8_t i2c_stop(uint16_t timeout);`                                                                             |Stops the I2C driver.                                                                                                                                                        |
+|`uint8_t i2c_stop(void);`                                                                                         |Ends an I2C transaction.                                                                                                                                                     |
 
 ### Function Return
 
diff --git a/drivers/arm/i2c_master.c b/drivers/arm/i2c_master.c
index 50a30ebce..0e5edcc38 100644
--- a/drivers/arm/i2c_master.c
+++ b/drivers/arm/i2c_master.c
@@ -101,8 +101,7 @@ uint8_t i2c_readReg(uint8_t devaddr, uint8_t* regaddr, uint8_t* data, uint16_t l
   return i2cMasterTransmitTimeout(&I2C_DRIVER, (i2c_address >> 1), regaddr, 1, data, length, MS2ST(timeout));
 }
 
-// This is usually not needed. It releases the driver to allow pins to become GPIO again.
-uint8_t i2c_stop(uint16_t timeout)
+uint8_t i2c_stop(void)
 {
   i2cStop(&I2C_DRIVER);
   return 0;
diff --git a/drivers/arm/i2c_master.h b/drivers/arm/i2c_master.h
index 7a9eb32eb..4ab2301f8 100644
--- a/drivers/arm/i2c_master.h
+++ b/drivers/arm/i2c_master.h
@@ -47,4 +47,4 @@ uint8_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t ti
 uint8_t i2c_transmit_receive(uint8_t address, uint8_t * tx_body, uint16_t tx_length, uint8_t * rx_body, uint16_t rx_length);
 uint8_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
 uint8_t i2c_readReg(uint8_t devaddr, uint8_t* regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
-uint8_t i2c_stop(uint16_t timeout);
+uint8_t i2c_stop(void);
diff --git a/drivers/avr/i2c_master.c b/drivers/avr/i2c_master.c
index 19bae33e9..d97a35cd6 100755
--- a/drivers/avr/i2c_master.c
+++ b/drivers/avr/i2c_master.c
@@ -7,43 +7,44 @@
 
 #include "i2c_master.h"
 #include "timer.h"
+#include "wait.h"
 
 #ifndef F_SCL
-#define F_SCL 400000UL // SCL frequency
+#  define F_SCL 400000UL  // SCL frequency
 #endif
 #define Prescaler 1
-#define TWBR_val ((((F_CPU / F_SCL) / Prescaler) - 16 ) / 2)
+#define TWBR_val ((((F_CPU / F_SCL) / Prescaler) - 16) / 2)
 
-void i2c_init(void)
-{
-  TWSR = 0;     /* no prescaler */
+void i2c_init(void) {
+  TWSR = 0; /* no prescaler */
   TWBR = (uint8_t)TWBR_val;
 }
 
-i2c_status_t i2c_start(uint8_t address, uint16_t timeout)
-{
+i2c_status_t i2c_start(uint8_t address, uint16_t timeout) {
   // reset TWI control register
   TWCR = 0;
   // transmit START condition
-  TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
+  TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
 
   uint16_t timeout_timer = timer_read();
-  while( !(TWCR & (1<<TWINT)) ) {
+  while (!(TWCR & (1 << TWINT))) {
     if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
       return I2C_STATUS_TIMEOUT;
     }
   }
 
   // check if the start condition was successfully transmitted
-  if(((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)){ return I2C_STATUS_ERROR; }
+  if (((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)) {
+    return I2C_STATUS_ERROR;
+  }
 
   // load slave address into data register
   TWDR = address;
   // start transmission of address
-  TWCR = (1<<TWINT) | (1<<TWEN);
+  TWCR = (1 << TWINT) | (1 << TWEN);
 
   timeout_timer = timer_read();
-  while( !(TWCR & (1<<TWINT)) ) {
+  while (!(TWCR & (1 << TWINT))) {
     if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
       return I2C_STATUS_TIMEOUT;
     }
@@ -51,38 +52,39 @@ i2c_status_t i2c_start(uint8_t address, uint16_t timeout)
 
   // check if the device has acknowledged the READ / WRITE mode
   uint8_t twst = TW_STATUS & 0xF8;
-  if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return I2C_STATUS_ERROR;
+  if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)) {
+    return I2C_STATUS_ERROR;
+  }
 
   return I2C_STATUS_SUCCESS;
 }
 
-i2c_status_t i2c_write(uint8_t data, uint16_t timeout)
-{
+i2c_status_t i2c_write(uint8_t data, uint16_t timeout) {
   // load data into data register
   TWDR = data;
   // start transmission of data
-  TWCR = (1<<TWINT) | (1<<TWEN);
+  TWCR = (1 << TWINT) | (1 << TWEN);
 
   uint16_t timeout_timer = timer_read();
-  while( !(TWCR & (1<<TWINT)) ) {
+  while (!(TWCR & (1 << TWINT))) {
     if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
       return I2C_STATUS_TIMEOUT;
     }
   }
 
-  if( (TW_STATUS & 0xF8) != TW_MT_DATA_ACK ){ return I2C_STATUS_ERROR; }
+  if ((TW_STATUS & 0xF8) != TW_MT_DATA_ACK) {
+    return I2C_STATUS_ERROR;
+  }
 
   return I2C_STATUS_SUCCESS;
 }
 
-int16_t i2c_read_ack(uint16_t timeout)
-{
-
+int16_t i2c_read_ack(uint16_t timeout) {
   // start TWI module and acknowledge data after reception
-  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
+  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWEA);
 
   uint16_t timeout_timer = timer_read();
-  while( !(TWCR & (1<<TWINT)) ) {
+  while (!(TWCR & (1 << TWINT))) {
     if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
       return I2C_STATUS_TIMEOUT;
     }
@@ -92,14 +94,12 @@ int16_t i2c_read_ack(uint16_t timeout)
   return TWDR;
 }
 
-int16_t i2c_read_nack(uint16_t timeout)
-{
-
+int16_t i2c_read_nack(uint16_t timeout) {
   // start receiving without acknowledging reception
-  TWCR = (1<<TWINT) | (1<<TWEN);
+  TWCR = (1 << TWINT) | (1 << TWEN);
 
   uint16_t timeout_timer = timer_read();
-  while( !(TWCR & (1<<TWINT)) ) {
+  while (!(TWCR & (1 << TWINT))) {
     if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
       return I2C_STATUS_TIMEOUT;
     }
@@ -109,115 +109,89 @@ int16_t i2c_read_nack(uint16_t timeout)
   return TWDR;
 }
 
-i2c_status_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)
-{
+i2c_status_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout) {
   i2c_status_t status = i2c_start(address | I2C_WRITE, timeout);
-  if (status) return status;
 
-  for (uint16_t i = 0; i < length; i++) {
+  for (uint16_t i = 0; i < length && status >= 0; i++) {
     status = i2c_write(data[i], timeout);
-    if (status) return status;
   }
 
-  status = i2c_stop(timeout);
-  if (status) return status;
+  i2c_stop();
 
-  return I2C_STATUS_SUCCESS;
+  return status;
 }
 
-i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)
-{
+i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout) {
   i2c_status_t status = i2c_start(address | I2C_READ, timeout);
-  if (status) return status;
 
-  for (uint16_t i = 0; i < (length-1); i++) {
+  for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) {
     status = i2c_read_ack(timeout);
     if (status >= 0) {
       data[i] = status;
-    } else {
-      return status;
     }
   }
 
-  status = i2c_read_nack(timeout);
-  if (status >= 0 ) {
-    data[(length-1)] = status;
-  } else {
-    return status;
+  if (status >= 0) {
+    status = i2c_read_nack(timeout);
+    if (status >= 0) {
+      data[(length - 1)] = status;
+    }
   }
 
-  status = i2c_stop(timeout);
-  if (status) return status;
+  i2c_stop();
 
-  return I2C_STATUS_SUCCESS;
+  return status;
 }
 
-i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)
-{
+i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout) {
   i2c_status_t status = i2c_start(devaddr | 0x00, timeout);
-  if (status) return status;
-
-  status = i2c_write(regaddr, timeout);
-  if (status) return status;
+  if (status >= 0) {
+    status = i2c_write(regaddr, timeout);
 
-  for (uint16_t i = 0; i < length; i++) {
-    status = i2c_write(data[i], timeout);
-    if (status) return status;
+    for (uint16_t i = 0; i < length && status >= 0; i++) {
+      status = i2c_write(data[i], timeout);
+    }
   }
 
-  status = i2c_stop(timeout);
-  if (status) return status;
+  i2c_stop();
 
-  return I2C_STATUS_SUCCESS;
+  return status;
 }
 
-i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)
-{
+i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout) {
   i2c_status_t status = i2c_start(devaddr, timeout);
-  if (status) return status;
+  if (status < 0) {
+    goto error;
+  }
 
   status = i2c_write(regaddr, timeout);
-  if (status) return status;
-
-  status = i2c_stop(timeout);
-  if (status) return status;
+  if (status < 0) {
+    goto error;
+  }
 
   status = i2c_start(devaddr | 0x01, timeout);
-  if (status) return status;
 
-  for (uint16_t i = 0; i < (length-1); i++) {
+  for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) {
     status = i2c_read_ack(timeout);
     if (status >= 0) {
       data[i] = status;
-    } else {
-      return status;
     }
   }
 
-  status = i2c_read_nack(timeout);
-  if (status >= 0 ) {
-    data[(length-1)] = status;
-  } else {
-    return status;
+  if (status >= 0) {
+    status = i2c_read_nack(timeout);
+    if (status >= 0) {
+      data[(length - 1)] = status;
+    }
   }
 
-  status = i2c_stop(timeout);
-  if (status) return status;
+error:
+  i2c_stop();
 
-  return I2C_STATUS_SUCCESS;
+  return status;
 }
 
-i2c_status_t i2c_stop(uint16_t timeout)
-{
+void i2c_stop(void) {
   // transmit STOP condition
-  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
-
-  uint16_t timeout_timer = timer_read();
-  while(TWCR & (1<<TWSTO)) {
-    if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
-      return I2C_STATUS_TIMEOUT;
-    }
-  }
-
-  return I2C_STATUS_SUCCESS;
+  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
 }
diff --git a/drivers/avr/i2c_master.h b/drivers/avr/i2c_master.h
index 89c64599c..81a7fb5e3 100755
--- a/drivers/avr/i2c_master.h
+++ b/drivers/avr/i2c_master.h
@@ -26,6 +26,6 @@ i2c_status_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length, uint1
 i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout);
 i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
 i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_stop(uint16_t timeout);
+void i2c_stop(void);
 
 #endif // I2C_MASTER_H
\ No newline at end of file
diff --git a/drivers/avr/i2c_slave.c b/drivers/avr/i2c_slave.c
index 18a29a45a..dbb9fb0df 100755
--- a/drivers/avr/i2c_slave.c
+++ b/drivers/avr/i2c_slave.c
@@ -16,7 +16,7 @@ static volatile bool slave_has_register_set = false;
 
 void i2c_slave_init(uint8_t address){
     // load address into TWI address register
-    TWAR = (address << 1);
+    TWAR = address;
     // set the TWCR to enable address matching and enable TWI, clear TWINT, enable TWI interrupt
     TWCR = (1 << TWIE) | (1 << TWEA) | (1 << TWINT) | (1 << TWEN);
 }
diff --git a/keyboards/cannonkeys/satisfaction75/i2c_master.c b/keyboards/cannonkeys/satisfaction75/i2c_master.c
index a19dbcc9f..d81eb92d4 100644
--- a/keyboards/cannonkeys/satisfaction75/i2c_master.c
+++ b/keyboards/cannonkeys/satisfaction75/i2c_master.c
@@ -109,7 +109,7 @@ uint8_t i2c_readReg(uint8_t devaddr, uint8_t* regaddr, uint8_t* data, uint16_t l
 }
 
 // This is usually not needed. It releases the driver to allow pins to become GPIO again.
-uint8_t i2c_stop(uint16_t timeout)
+uint8_t i2c_stop(void)
 {
   i2cStop(&I2C_DRIVER);
   return 0;
diff --git a/keyboards/dc01/left/matrix.c b/keyboards/dc01/left/matrix.c
index cbe3b3f3d..a3db220e4 100644
--- a/keyboards/dc01/left/matrix.c
+++ b/keyboards/dc01/left/matrix.c
@@ -455,10 +455,10 @@ i2c_status_t i2c_transaction(uint8_t address, uint32_t mask, uint8_t col_offset)
         matrix[MATRIX_ROWS - 1] |= ((uint32_t)err << (MATRIX_COLS_SCANNED + col_offset)); //add new bits at the end
 
     } else {
-        i2c_stop(10);
+        i2c_stop();
         return 1;
     }
 
-    i2c_stop(10);
+    i2c_stop();
     return 0;
 }
\ No newline at end of file
diff --git a/keyboards/ergodox_ez/ergodox_ez.c b/keyboards/ergodox_ez/ergodox_ez.c
index 3b2c94350..b27a6b89d 100644
--- a/keyboards/ergodox_ez/ergodox_ez.c
+++ b/keyboards/ergodox_ez/ergodox_ez.c
@@ -128,7 +128,7 @@ uint8_t init_mcp23018(void) {
     mcp23018_status = i2c_write(IODIRA, ERGODOX_EZ_I2C_TIMEOUT);            if (mcp23018_status) goto out;
     mcp23018_status = i2c_write(0b00000000, ERGODOX_EZ_I2C_TIMEOUT);        if (mcp23018_status) goto out;
     mcp23018_status = i2c_write(0b00111111, ERGODOX_EZ_I2C_TIMEOUT);        if (mcp23018_status) goto out;
-    i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+    i2c_stop();
 
     // set pull-up
     // - unused  : on  : 1
@@ -140,7 +140,7 @@ uint8_t init_mcp23018(void) {
     mcp23018_status = i2c_write(0b00111111, ERGODOX_EZ_I2C_TIMEOUT);        if (mcp23018_status) goto out;
 
 out:
-    i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+    i2c_stop();
 
 #ifdef LEFT_LEDS
     if (!mcp23018_status) mcp23018_status = ergodox_left_leds_update();
@@ -179,7 +179,7 @@ uint8_t ergodox_left_leds_update(void) {
     if (mcp23018_status) goto out;
 
  out:
-    i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+    i2c_stop();
     return mcp23018_status;
 }
 #endif
diff --git a/keyboards/ergodox_ez/matrix.c b/keyboards/ergodox_ez/matrix.c
index 22837d312..860cf7b22 100644
--- a/keyboards/ergodox_ez/matrix.c
+++ b/keyboards/ergodox_ez/matrix.c
@@ -309,7 +309,7 @@ static matrix_row_t read_cols(uint8_t row)
             data = ~((uint8_t)mcp23018_status);
             mcp23018_status = I2C_STATUS_SUCCESS;
         out:
-            i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+            i2c_stop();
             return data;
         }
     } else {
@@ -362,7 +362,7 @@ static void select_row(uint8_t row)
             mcp23018_status = i2c_write(GPIOA, ERGODOX_EZ_I2C_TIMEOUT);                 if (mcp23018_status) goto out;
             mcp23018_status = i2c_write(0xFF & ~(1<<row), ERGODOX_EZ_I2C_TIMEOUT);      if (mcp23018_status) goto out;
         out:
-            i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+            i2c_stop();
         }
     } else {
         // select on teensy
diff --git a/keyboards/gergo/gergo.c b/keyboards/gergo/gergo.c
index d32792e2a..cc0bef391 100644
--- a/keyboards/gergo/gergo.c
+++ b/keyboards/gergo/gergo.c
@@ -47,7 +47,7 @@ uint8_t init_mcp23018(void) {
     mcp23018_status = i2c_write(IODIRA, ERGODOX_EZ_I2C_TIMEOUT);            if (mcp23018_status) goto out;
     mcp23018_status = i2c_write(0b10000000, ERGODOX_EZ_I2C_TIMEOUT);        if (mcp23018_status) goto out;
     mcp23018_status = i2c_write(0b11111111, ERGODOX_EZ_I2C_TIMEOUT);        if (mcp23018_status) goto out;
-    i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+    i2c_stop();
 
     // set pull-up
     // - unused  : on  : 1
@@ -59,7 +59,7 @@ uint8_t init_mcp23018(void) {
     mcp23018_status = i2c_write(0b11111111, ERGODOX_EZ_I2C_TIMEOUT);        if (mcp23018_status) goto out;
 
 out:
-    i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+    i2c_stop();
     // SREG=sreg_prev;
     //uprintf("Init %x\n", mcp23018_status);
     return mcp23018_status;
diff --git a/keyboards/gergo/matrix.c b/keyboards/gergo/matrix.c
index 29fe48ccb..9886ecf15 100644
--- a/keyboards/gergo/matrix.c
+++ b/keyboards/gergo/matrix.c
@@ -72,14 +72,14 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //Trackball pin defs
 #define TRKUP (1<<4)
 #define TRKDN (1<<5)
-#define TRKLT (1<<6) 
+#define TRKLT (1<<6)
 #define TRKRT (1<<7)
 #define TRKBTN (1<<6)
 
 
 // Multiple for mouse moves
 #ifndef TRKSTEP
-#define TRKSTEP 20 
+#define TRKSTEP 20
 #endif
 
 // multiple for mouse scroll
@@ -98,13 +98,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 // Trackball interrupts accumulate over here. Processed on scan
 // Stores prev state of mouse, high bits store direction
-uint8_t trkState    = 0; 
-uint8_t trkBtnState = 0; 
+uint8_t trkState    = 0;
+uint8_t trkBtnState = 0;
 
-volatile uint8_t tbUpCnt  = 0; 
-volatile uint8_t tbDnCnt  = 0; 
-volatile uint8_t tbLtCnt  = 0; 
-volatile uint8_t tbRtCnt  = 0; 
+volatile uint8_t tbUpCnt  = 0;
+volatile uint8_t tbDnCnt  = 0;
+volatile uint8_t tbLtCnt  = 0;
+volatile uint8_t tbRtCnt  = 0;
 
 /* matrix state(1:on, 0:off) */
 static matrix_row_t matrix[MATRIX_ROWS];
@@ -240,14 +240,14 @@ uint8_t matrix_scan(void)
   // First we handle the mouse inputs
   #ifdef BALLER
   uint8_t pBtn   = PINE & TRKBTN;
-  
+
   #ifdef DEBUG_BALLER
-  // Compare to previous, mod report 
+  // Compare to previous, mod report
   if (tbUpCnt + tbDnCnt + tbLtCnt + tbRtCnt != 0)
     xprintf("U: %d D: %d L: %d R: %d B: %d\n", tbUpCnt, tbDnCnt, tbLtCnt, tbRtCnt, (trkBtnState >> 6));
   #endif
 
-  // Modify the report 
+  // Modify the report
   report_mouse_t pRprt = pointing_device_get_report();
 
   // Scroll by default, move on layer
@@ -264,7 +264,7 @@ uint8_t matrix_scan(void)
   }
 
   #ifdef DEBUG_BALLER
-  if (pRprt.x != 0 || pRprt.y != 0) 
+  if (pRprt.x != 0 || pRprt.y != 0)
 	xprintf("X: %d Y: %d\n", pRprt.x, pRprt.y);
   #endif
 
@@ -272,7 +272,7 @@ uint8_t matrix_scan(void)
   if ((pBtn != trkBtnState) && ((pBtn >> 6) == 1))  pRprt.buttons &= ~MOUSE_BTN1;
 
   // Save state, push update
-  if (pRprt.x != 0 || pRprt.y != 0 || pRprt.h != 0 || pRprt.v != 0 || (trkBtnState != pBtn)) 
+  if (pRprt.x != 0 || pRprt.y != 0 || pRprt.h != 0 || pRprt.v != 0 || (trkBtnState != pBtn))
     pointing_device_set_report(pRprt);
 
   trkBtnState = pBtn;
@@ -325,8 +325,8 @@ uint8_t matrix_scan(void)
     enableInterrupts();
 
 #ifdef DEBUG_MATRIX
-    for (uint8_t c = 0; c < MATRIX_COLS; c++) 
-		for (uint8_t r = 0; r < MATRIX_ROWS; r++) 
+    for (uint8_t c = 0; c < MATRIX_COLS; c++)
+		for (uint8_t r = 0; r < MATRIX_ROWS; r++)
 		  if (matrix_is_on(r, c)) xprintf("r:%d c:%d \n", r, c);
 #endif
 
@@ -394,7 +394,7 @@ static matrix_row_t read_cols(uint8_t row)
             data = ~((uint8_t)mcp23018_status);
             mcp23018_status = I2C_STATUS_SUCCESS;
         out:
-            i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+            i2c_stop();
 
 #ifdef DEBUG_MATRIX
             if (data != 0x00) xprintf("I2C: %d\n", data);
@@ -439,12 +439,12 @@ static void select_row(uint8_t row)
     if (row < 7) {
         // select on mcp23018
         if (mcp23018_status) { // do nothing on error
-        } else { // set active row low  : 0 // set other rows hi-Z : 1 
+        } else { // set active row low  : 0 // set other rows hi-Z : 1
             mcp23018_status = i2c_start(I2C_ADDR_WRITE, ERGODOX_EZ_I2C_TIMEOUT);        if (mcp23018_status) goto out;
             mcp23018_status = i2c_write(GPIOA, ERGODOX_EZ_I2C_TIMEOUT);                 if (mcp23018_status) goto out;
             mcp23018_status = i2c_write(0xFF & ~(1<<row), ERGODOX_EZ_I2C_TIMEOUT);      if (mcp23018_status) goto out;
         out:
-            i2c_stop(ERGODOX_EZ_I2C_TIMEOUT);
+            i2c_stop();
         }
     } else {
         // Output low(DDR:1, PORT:0) to select
diff --git a/quantum/keymap_common.c b/quantum/keymap_common.c
index 9d2d331ce..eef739a14 100644
--- a/quantum/keymap_common.c
+++ b/quantum/keymap_common.c
@@ -29,10 +29,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "backlight.h"
 #include "quantum.h"
 
-#ifdef SPLIT_KEYBOARD
-    #include "split_flags.h"
-#endif
-
 #ifdef MIDI_ENABLE
 	#include "process_midi.h"
 #endif
@@ -138,39 +134,21 @@ action_t action_for_key(uint8_t layer, keypos_t key)
     #ifdef BACKLIGHT_ENABLE
         case BL_ON:
             action.code = ACTION_BACKLIGHT_ON();
-            #ifdef SPLIT_KEYBOARD
-                BACKLIT_DIRTY = true;
-            #endif
             break;
         case BL_OFF:
             action.code = ACTION_BACKLIGHT_OFF();
-            #ifdef SPLIT_KEYBOARD
-                BACKLIT_DIRTY = true;
-            #endif
             break;
         case BL_DEC:
             action.code = ACTION_BACKLIGHT_DECREASE();
-            #ifdef SPLIT_KEYBOARD
-                BACKLIT_DIRTY = true;
-            #endif
             break;
         case BL_INC:
             action.code = ACTION_BACKLIGHT_INCREASE();
-            #ifdef SPLIT_KEYBOARD
-                BACKLIT_DIRTY = true;
-            #endif
             break;
         case BL_TOGG:
             action.code = ACTION_BACKLIGHT_TOGGLE();
-            #ifdef SPLIT_KEYBOARD
-                BACKLIT_DIRTY = true;
-            #endif
             break;
         case BL_STEP:
             action.code = ACTION_BACKLIGHT_STEP();
-            #ifdef SPLIT_KEYBOARD
-                BACKLIT_DIRTY = true;
-            #endif
             break;
     #endif
     #ifdef SWAP_HANDS_ENABLE
diff --git a/quantum/quantum.c b/quantum/quantum.c
index 46d404029..8316d1f06 100644
--- a/quantum/quantum.c
+++ b/quantum/quantum.c
@@ -360,9 +360,6 @@ bool process_record_quantum(keyrecord_t *record) {
     if (!record->event.pressed) {
     #endif
       rgblight_toggle();
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_MODE_FORWARD:
@@ -374,9 +371,6 @@ bool process_record_quantum(keyrecord_t *record) {
       else {
         rgblight_step();
       }
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_MODE_REVERSE:
@@ -388,9 +382,6 @@ bool process_record_quantum(keyrecord_t *record) {
       else {
         rgblight_step_reverse();
       }
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_HUI:
@@ -401,9 +392,6 @@ bool process_record_quantum(keyrecord_t *record) {
     if (!record->event.pressed) {
     #endif
       rgblight_increase_hue();
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_HUD:
@@ -414,9 +402,6 @@ bool process_record_quantum(keyrecord_t *record) {
     if (!record->event.pressed) {
     #endif
       rgblight_decrease_hue();
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_SAI:
@@ -427,9 +412,6 @@ bool process_record_quantum(keyrecord_t *record) {
     if (!record->event.pressed) {
     #endif
       rgblight_increase_sat();
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_SAD:
@@ -440,9 +422,6 @@ bool process_record_quantum(keyrecord_t *record) {
     if (!record->event.pressed) {
     #endif
       rgblight_decrease_sat();
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_VAI:
@@ -453,9 +432,6 @@ bool process_record_quantum(keyrecord_t *record) {
     if (!record->event.pressed) {
     #endif
       rgblight_increase_val();
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_VAD:
@@ -466,9 +442,6 @@ bool process_record_quantum(keyrecord_t *record) {
     if (!record->event.pressed) {
     #endif
       rgblight_decrease_val();
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_SPI:
@@ -484,9 +457,6 @@ bool process_record_quantum(keyrecord_t *record) {
   case RGB_MODE_PLAIN:
     if (record->event.pressed) {
       rgblight_mode(RGBLIGHT_MODE_STATIC_LIGHT);
-      #ifdef SPLIT_KEYBOARD
-          RGB_DIRTY = true;
-      #endif
     }
     return false;
   case RGB_MODE_BREATHE:
diff --git a/quantum/quantum.h b/quantum/quantum.h
index d2c5862f8..c12ac9ab8 100644
--- a/quantum/quantum.h
+++ b/quantum/quantum.h
@@ -44,10 +44,6 @@
     #endif
 #endif
 
-#ifdef SPLIT_KEYBOARD
-    #include "split_flags.h"
-#endif
-
 #ifdef RGB_MATRIX_ENABLE
     #include "rgb_matrix.h"
 #endif
diff --git a/quantum/split_common/i2c.c b/quantum/split_common/i2c.c
deleted file mode 100644
index 45e958b39..000000000
--- a/quantum/split_common/i2c.c
+++ /dev/null
@@ -1,184 +0,0 @@
-#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"
-#include "split_flags.h"
-
-// 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
-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;
-}
-
-uint8_t i2c_master_write_data(void *const TXdata, uint8_t dataLen) {
-    
-    uint8_t *data = (uint8_t *)TXdata;
-    int err = 0;
-    
-    for (int i = 0; i < dataLen; i++) {
-        err = i2c_master_write(data[i]);
-        
-        if ( err )
-            return err;
-    }
-    
-    return err;
-    
-}
-
-// 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;
-        
-        if ( slave_buffer_pos == I2C_BACKLIT_START) {
-            BACKLIT_DIRTY = true;
-        } else if ( slave_buffer_pos == (I2C_RGB_START+3)) {
-            RGB_DIRTY = true;
-        }
-        
-        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);
-}
diff --git a/quantum/split_common/i2c.h b/quantum/split_common/i2c.h
deleted file mode 100644
index 91e8e96f4..000000000
--- a/quantum/split_common/i2c.h
+++ /dev/null
@@ -1,59 +0,0 @@
-#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
-
-// Address location defines (Keymap should be last, as it's size is dynamic)
-#define I2C_BACKLIT_START   0x00
-// Need 4 bytes for RGB (32 bit)
-#define I2C_RGB_START       0x01
-#define I2C_KEYMAP_START    0x06
-
-// Slave buffer (8bit per)
-// Rows per hand + backlit space + rgb space
-// TODO : Make this dynamically sized
-#define SLAVE_BUFFER_SIZE 0x20
-
-// i2c SCL clock frequency
-#ifndef SCL_CLOCK
-#define SCL_CLOCK  100000L
-#endif
-
-// Support 8bits right now (8 cols) will need to edit to take higher (code exists in delta split?)
-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_write_data(void *const TXdata, uint8_t dataLen);
-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/quantum/split_common/matrix.c b/quantum/split_common/matrix.c
index f2a277c69..dcb96254f 100644
--- a/quantum/split_common/matrix.c
+++ b/quantum/split_common/matrix.c
@@ -25,7 +25,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "matrix.h"
 #include "split_util.h"
 #include "config.h"
-#include "split_flags.h"
 #include "quantum.h"
 #include "debounce.h"
 #include "transport.h"
diff --git a/quantum/split_common/split_flags.c b/quantum/split_common/split_flags.c
deleted file mode 100644
index 1f5825d65..000000000
--- a/quantum/split_common/split_flags.c
+++ /dev/null
@@ -1,5 +0,0 @@
-#include "split_flags.h"
-
-volatile bool RGB_DIRTY = false;
-
-volatile bool BACKLIT_DIRTY = false;
\ No newline at end of file
diff --git a/quantum/split_common/split_flags.h b/quantum/split_common/split_flags.h
deleted file mode 100644
index aaac474a7..000000000
--- a/quantum/split_common/split_flags.h
+++ /dev/null
@@ -1,15 +0,0 @@
-#pragma once
-
-#include <stdbool.h>
-#include <stdint.h>
-
-/**
-* Global Flags
-**/
-
-//RGB Stuff
-extern volatile bool RGB_DIRTY;
-
-
-//Backlight Stuff
-extern volatile bool BACKLIT_DIRTY;
diff --git a/quantum/split_common/split_util.c b/quantum/split_common/split_util.c
index 5095cb8fd..da870f877 100644
--- a/quantum/split_common/split_util.c
+++ b/quantum/split_common/split_util.c
@@ -3,7 +3,6 @@
 #include "keyboard.h"
 #include "config.h"
 #include "timer.h"
-#include "split_flags.h"
 #include "transport.h"
 #include "quantum.h"
 
@@ -60,10 +59,6 @@ static void keyboard_master_setup(void) {
   #endif
 #endif
   transport_master_init();
-
-  // For master the Backlight info needs to be sent on startup
-  // Otherwise the salve won't start with the proper info until an update
-  BACKLIT_DIRTY = true;
 }
 
 static void keyboard_slave_setup(void)
diff --git a/quantum/split_common/transport.c b/quantum/split_common/transport.c
index 95738530e..b16852bc1 100644
--- a/quantum/split_common/transport.c
+++ b/quantum/split_common/transport.c
@@ -3,146 +3,83 @@
 #include "matrix.h"
 #include "quantum.h"
 
-#define ROWS_PER_HAND (MATRIX_ROWS/2)
+#define ROWS_PER_HAND (MATRIX_ROWS / 2)
 
 #ifdef RGBLIGHT_ENABLE
-#   include "rgblight.h"
+#  include "rgblight.h"
 #endif
 
 #ifdef BACKLIGHT_ENABLE
-# include "backlight.h"
-  extern backlight_config_t backlight_config;
+#  include "backlight.h"
+extern backlight_config_t backlight_config;
 #endif
 
 #if defined(USE_I2C) || defined(EH)
 
-#include "i2c.h"
+#  include "i2c_master.h"
+#  include "i2c_slave.h"
 
-#ifndef SLAVE_I2C_ADDRESS
-#  define SLAVE_I2C_ADDRESS           0x32
-#endif
+#  define I2C_BACKLIT_START 0x00
+// Need 4 bytes for RGB (32 bit)
+#  define I2C_RGB_START 0x01
+#  define I2C_KEYMAP_START 0x05
 
-#if (MATRIX_COLS > 8)
-#  error "Currently only supports 8 COLS"
-#endif
+#  define TIMEOUT 100
+
+#  ifndef SLAVE_I2C_ADDRESS
+#    define SLAVE_I2C_ADDRESS 0x32
+#  endif
 
 // Get rows from other half over i2c
 bool transport_master(matrix_row_t matrix[]) {
-  int err = 0;
+  i2c_readReg(SLAVE_I2C_ADDRESS, I2C_KEYMAP_START, (void *)matrix, ROWS_PER_HAND * sizeof(matrix_row_t), TIMEOUT);
 
   // write backlight info
-#ifdef BACKLIGHT_ENABLE
-  if (BACKLIT_DIRTY) {
-    err = i2c_master_start(SLAVE_I2C_ADDRESS + I2C_WRITE);
-    if (err) { goto i2c_error; }
-
-    // Backlight location
-    err = i2c_master_write(I2C_BACKLIT_START);
-    if (err) { goto i2c_error; }
-
-    // Write backlight
-    i2c_master_write(get_backlight_level());
-
-    BACKLIT_DIRTY = false;
-  }
-#endif
-
-  err = i2c_master_start(SLAVE_I2C_ADDRESS + I2C_WRITE);
-  if (err) { goto i2c_error; }
-
-  // start of matrix stored at I2C_KEYMAP_START
-  err = i2c_master_write(I2C_KEYMAP_START);
-  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[i] = i2c_master_read(I2C_ACK);
-    }
-    matrix[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 false;
+#  ifdef BACKLIGHT_ENABLE
+  static uint8_t prev_level = ~0;
+  uint8_t        level      = get_backlight_level();
+  if (level != prev_level) {
+    i2c_writeReg(SLAVE_I2C_ADDRESS, I2C_BACKLIT_START, (void *)&level, sizeof(level), TIMEOUT);
+    prev_level = level;
   }
-
-#ifdef RGBLIGHT_ENABLE
-  if (RGB_DIRTY) {
-    err = i2c_master_start(SLAVE_I2C_ADDRESS + I2C_WRITE);
-    if (err) { goto i2c_error; }
-
-    // RGB Location
-    err = i2c_master_write(I2C_RGB_START);
-    if (err) { goto i2c_error; }
-
-    uint32_t dword = eeconfig_read_rgblight();
-
-    // Write RGB
-    err = i2c_master_write_data(&dword, 4);
-    if (err) { goto i2c_error; }
-
-    RGB_DIRTY = false;
-    i2c_master_stop();
+#  endif
+
+#  ifdef RGBLIGHT_ENABLE
+  static uint32_t prev_rgb = ~0;
+  uint32_t        rgb      = eeconfig_read_rgblight();
+  if (rgb != prev_rgb) {
+    i2c_writeReg(SLAVE_I2C_ADDRESS, I2C_RGB_START, (void *)&rgb, sizeof(rgb), TIMEOUT);
+    prev_rgb = rgb;
   }
-#endif
+#  endif
 
   return true;
 }
 
 void transport_slave(matrix_row_t matrix[]) {
-
-  for (int i = 0; i < ROWS_PER_HAND; ++i)
-  {
-    i2c_slave_buffer[I2C_KEYMAP_START + i] = matrix[i];
-  }
-  // Read Backlight Info
-  #ifdef BACKLIGHT_ENABLE
-  if (BACKLIT_DIRTY)
-  {
-    backlight_set(i2c_slave_buffer[I2C_BACKLIT_START]);
-    BACKLIT_DIRTY = false;
+  for (int i = 0; i < ROWS_PER_HAND * sizeof(matrix_row_t); ++i) {
+    i2c_slave_reg[I2C_KEYMAP_START + i] = matrix[i];
   }
-  #endif
-  #ifdef RGBLIGHT_ENABLE
-  if (RGB_DIRTY)
-  {
-    // Disable interupts (RGB data is big)
-    cli();
-    // Create new DWORD for RGB data
-    uint32_t dword;
-
-    // Fill the new DWORD with the data that was sent over
-    uint8_t * dword_dat = (uint8_t *)(&dword);
-    for (int i = 0; i < 4; i++)
-    {
-      dword_dat[i] = i2c_slave_buffer[I2C_RGB_START + i];
-    }
-
-    // Update the RGB now with the new data and set RGB_DIRTY to false
-    rgblight_update_dword(dword);
-    RGB_DIRTY = false;
-    // Re-enable interupts now that RGB is set
-    sei();
-  }
-  #endif
-}
 
-void transport_master_init(void) {
-  i2c_master_init();
-}
+// Read Backlight Info
+#  ifdef BACKLIGHT_ENABLE
+  backlight_set(i2c_slave_reg[I2C_BACKLIT_START]);
+#  endif
 
-void transport_slave_init(void) {
-  i2c_slave_init(SLAVE_I2C_ADDRESS);
+#  ifdef RGBLIGHT_ENABLE
+  uint32_t rgb = *(uint32_t *)(i2c_slave_reg + I2C_RGB_START);
+  // Update the RGB with the new data
+  rgblight_update_dword(rgb);
+#  endif
 }
 
-#else // USE_SERIAL
+void transport_master_init(void) { i2c_init(); }
+
+void transport_slave_init(void) { i2c_slave_init(SLAVE_I2C_ADDRESS); }
 
-#include "serial.h"
+#else  // USE_SERIAL
+
+#  include "serial.h"
 
 typedef struct _Serial_s2m_buffer_t {
   // TODO: if MATRIX_COLS > 8 change to uint8_t packed_matrix[] for pack/unpack
@@ -150,40 +87,40 @@ typedef struct _Serial_s2m_buffer_t {
 } Serial_s2m_buffer_t;
 
 typedef struct _Serial_m2s_buffer_t {
-#ifdef BACKLIGHT_ENABLE
-    uint8_t backlight_level;
-#endif
-#if defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
-    rgblight_config_t rgblight_config; //not yet use
-    //
-    // When MCUs on both sides drive their respective RGB LED chains,
-    // it is necessary to synchronize, so it is necessary to communicate RGB information.
-    // In that case, define the RGBLIGHT_SPLIT macro.
-    //
-    // Otherwise, if the master side MCU drives both sides RGB LED chains,
-    // there is no need to communicate.
-#endif
+#  ifdef BACKLIGHT_ENABLE
+  uint8_t           backlight_level;
+#  endif
+#  if defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
+  rgblight_config_t rgblight_config;  // not yet use
+  //
+  // When MCUs on both sides drive their respective RGB LED chains,
+  // it is necessary to synchronize, so it is necessary to communicate RGB
+  // information. In that case, define the RGBLIGHT_SPLIT macro.
+  //
+  // Otherwise, if the master side MCU drives both sides RGB LED chains,
+  // there is no need to communicate.
+#  endif
 } Serial_m2s_buffer_t;
 
 volatile Serial_s2m_buffer_t serial_s2m_buffer = {};
 volatile Serial_m2s_buffer_t serial_m2s_buffer = {};
-uint8_t volatile status0 = 0;
+uint8_t volatile status0                       = 0;
 
 SSTD_t transactions[] = {
-  { (uint8_t *)&status0,
-    sizeof(serial_m2s_buffer), (uint8_t *)&serial_m2s_buffer,
-    sizeof(serial_s2m_buffer), (uint8_t *)&serial_s2m_buffer
-  }
+    {
+        (uint8_t *)&status0,
+        sizeof(serial_m2s_buffer),
+        (uint8_t *)&serial_m2s_buffer,
+        sizeof(serial_s2m_buffer),
+        (uint8_t *)&serial_s2m_buffer,
+    },
 };
 
-void transport_master_init(void)
-{ soft_serial_initiator_init(transactions, TID_LIMIT(transactions)); }
+void transport_master_init(void) { soft_serial_initiator_init(transactions, TID_LIMIT(transactions)); }
 
-void transport_slave_init(void)
-{ soft_serial_target_init(transactions, TID_LIMIT(transactions)); }
+void transport_slave_init(void) { soft_serial_target_init(transactions, TID_LIMIT(transactions)); }
 
 bool transport_master(matrix_row_t matrix[]) {
-
   if (soft_serial_transaction()) {
     return false;
   }
@@ -193,32 +130,29 @@ bool transport_master(matrix_row_t matrix[]) {
     matrix[i] = serial_s2m_buffer.smatrix[i];
   }
 
-  #if defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
-    // Code to send RGB over serial goes here (not implemented yet)
-  #endif
+#  if defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
+  // Code to send RGB over serial goes here (not implemented yet)
+#  endif
 
-  #ifdef BACKLIGHT_ENABLE
-    // Write backlight level for slave to read
-    serial_m2s_buffer.backlight_level = backlight_config.enable ? backlight_config.level : 0;
-  #endif
+#  ifdef BACKLIGHT_ENABLE
+  // Write backlight level for slave to read
+  serial_m2s_buffer.backlight_level = backlight_config.enable ? backlight_config.level : 0;
+#  endif
 
   return true;
 }
 
 void transport_slave(matrix_row_t matrix[]) {
-
   // TODO: if MATRIX_COLS > 8 change to pack()
-  for (int i = 0; i < ROWS_PER_HAND; ++i)
-  {
+  for (int i = 0; i < ROWS_PER_HAND; ++i) {
     serial_s2m_buffer.smatrix[i] = matrix[i];
   }
-  #ifdef BACKLIGHT_ENABLE
-    backlight_set(serial_m2s_buffer.backlight_level);
-  #endif
-  #if defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
-  // Add serial implementation for RGB here
-  #endif
-
+#  ifdef BACKLIGHT_ENABLE
+  backlight_set(serial_m2s_buffer.backlight_level);
+#  endif
+#  if defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
+// Add serial implementation for RGB here
+#  endif
 }
 
 #endif
diff --git a/tmk_core/common/avr/suspend.c b/tmk_core/common/avr/suspend.c
index b29447ac4..2259201b5 100644
--- a/tmk_core/common/avr/suspend.c
+++ b/tmk_core/common/avr/suspend.c
@@ -11,9 +11,6 @@
 #include "led.h"
 #include "host.h"
 #include "rgblight_reconfig.h"
-#ifdef SPLIT_KEYBOARD
-  #include "split_flags.h"
-#endif
 
 #ifdef PROTOCOL_LUFA
 	#include "lufa.h"
@@ -135,9 +132,6 @@ static void power_down(uint8_t wdto) {
     is_suspended = true;
     rgblight_enabled = rgblight_config.enable;
     rgblight_disable_noeeprom();
-    #ifdef SPLIT_KEYBOARD
-        RGB_DIRTY = true;
-    #endif
   }
 #endif
   suspend_power_down_kb();
@@ -216,9 +210,6 @@ void suspend_wakeup_init(void) {
       wait_ms(10);
     #endif
     rgblight_enable_noeeprom();
-    #ifdef SPLIT_KEYBOARD
-        RGB_DIRTY = true;
-    #endif
   }
 #ifdef RGBLIGHT_ANIMATIONS
   rgblight_timer_enable();