4 files changed, 46 insertions, 22 deletions

diff --git a/keyboards/lets_split_eh/eh/config.h b/keyboards/lets_split_eh/eh/config.h
index 5651ddd8b..59afb39c0 100644
--- a/keyboards/lets_split_eh/eh/config.h
+++ b/keyboards/lets_split_eh/eh/config.h
@@ -21,6 +21,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 // To let configuration know this is of type EH, which will force I2C irregardless of user config
 #define EH
+// The 'EH' only uses I2C
+#define USE_I2C
 
 #include "config_common.h"
 
diff --git a/quantum/split_common/matrix.c b/quantum/split_common/matrix.c
index 071f0481a..5e5475f44 100644
--- a/quantum/split_common/matrix.c
+++ b/quantum/split_common/matrix.c
@@ -286,6 +286,16 @@ int serial_transaction(void) {
     for (int i = 0; i < ROWS_PER_HAND; ++i) {
         matrix[slaveOffset+i] = serial_slave_buffer[i];
     }
+    
+    #ifdef RGBLIGHT_ENABLE
+        // Code to send RGB over serial goes here (not implemented yet)
+    #endif
+    
+    #ifdef BACKLIGHT_ENABLE
+        // Write backlight level for slave to read
+        serial_master_buffer[SERIAL_BACKLIT_START] = backlight_config.enable ? backlight_config.level : 0;
+    #endif
+
     return 0;
 }
 #endif
diff --git a/quantum/split_common/serial.h b/quantum/split_common/serial.h
index 15fe4db7b..e566eb8a0 100644
--- a/quantum/split_common/serial.h
+++ b/quantum/split_common/serial.h
@@ -14,6 +14,9 @@
 #define SERIAL_SLAVE_BUFFER_LENGTH MATRIX_ROWS/2
 #define SERIAL_MASTER_BUFFER_LENGTH 1
 
+// Address location defines 
+#define SERIAL_BACKLIT_START   0x00
+
 // Buffers for master - slave communication
 extern volatile uint8_t serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH];
 extern volatile uint8_t serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH];
diff --git a/quantum/split_common/split_util.c b/quantum/split_common/split_util.c
index 340a63137..13b09d5b8 100644
--- a/quantum/split_common/split_util.c
+++ b/quantum/split_common/split_util.c
@@ -101,35 +101,44 @@ void keyboard_slave_loop(void) {
    #endif
 
    while (1) {
-      matrix_slave_scan();
-      
-      // read backlight info
+    // Matrix Slave Scan
+    matrix_slave_scan();
+    
+    // Read Backlight Info
     #ifdef BACKLIGHT_ENABLE
         if (BACKLIT_DIRTY) {
-            backlight_set(i2c_slave_buffer[I2C_BACKLIT_START]);
+            #ifdef USE_I2C
+                backlight_set(i2c_slave_buffer[I2C_BACKLIT_START]);
+            #else // USE_SERIAL
+                backlight_set(serial_master_buffer[SERIAL_BACKLIT_START]);
+            #endif
             BACKLIT_DIRTY = false;
         }
     #endif
+    // Read RGB Info
     #ifdef RGBLIGHT_ENABLE
-        if (RGB_DIRTY) {
-            cli();
-            uint32_t dword;
-            
-            /*dword = i2c_slave_buffer[I2C_RGB_START + 3];
-            dword = (dword << 8) + i2c_slave_buffer[I2C_RGB_START + 2];
-            dword = (dword << 8) + i2c_slave_buffer[I2C_RGB_START + 1];
-            dword = (dword << 8) + i2c_slave_buffer[I2C_RGB_START];*/
-            
-            
-            uint8_t *dword_dat = (uint8_t *)(&dword);
-            for (int i = 0; i < 4; i++) {
-                dword_dat[i] = i2c_slave_buffer[I2C_RGB_START+i];
+        #ifdef USE_I2C
+            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();
             }
-
-            rgblight_update_dword(dword);
-            RGB_DIRTY = false;
-            sei();
-        }
+        #else // USE_SERIAL
+            // Add serial implementation for RGB here
+        #endif
     #endif
    }
 }