add '//#define SOFT_SERIAL_PIN D0' to keyboards/lets_split_eh/config.h

keyboards/lets_split_eh/config.h

@@ -36,6 +36,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 /* Set 0 if debouncing isn't needed */
 #define DEBOUNCING_DELAY 5
 
+/* serial.c configuration for split keyboard */
+//#define SOFT_SERIAL_PIN D0
+
 /* key combination for command */
 #define IS_COMMAND() ( \
     keyboard_report->mods == (MOD_BIT(KC_LSHIFT) | MOD_BIT(KC_RSHIFT)) \

quantum/split_common/split-keyboards-list.txt

@@ -7,7 +7,7 @@ ok keyboards/handwired/dactyl_manuform/rules.mk:SPLIT_KEYBOARD = yes
 ok keyboards/handwired/qc60/rules.mk:SPLIT_KEYBOARD = yes
 ok keyboards/handwired/xealous/rules.mk:SPLIT_KEYBOARD = yes        # Use shared split_common code
 ok keyboards/iris/rules.mk:SPLIT_KEYBOARD = yes
-keyboards/lets_split_eh/rules.mk:SPLIT_KEYBOARD = yes
+ok keyboards/lets_split_eh/rules.mk:SPLIT_KEYBOARD = yes
 keyboards/levinson/rules.mk:SPLIT_KEYBOARD = yes
 keyboards/miniaxe/rules.mk:SPLIT_KEYBOARD = yes        # Use shared split_common code
 keyboards/nyquist/rules.mk:SPLIT_KEYBOARD = yes