Allow invert of SPLIT_HAND_PIN logic (#13433)

* added support for inverting the hand pin for split keyboards

* Added docs about SPLIT_HAND_LOW_IS_LEFT

* Update docs/feature_split_keyboard.md

bring #define for split hand pin low for left half name in line with grid pin define

Co-authored-by: Joel Challis <git@zvecr.com>

* Update quantum/split_common/split_util.c

update split hand pin low is left name to match split hand grid define

Co-authored-by: Joel Challis <git@zvecr.com>

Co-authored-by: Joel Challis <git@zvecr.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/quantum/split_common/split_util.c b/quantum/split_common/split_util.c
index 9e75e19ce..989829d2d 100644
--- a/quantum/split_common/split_util.c
+++ b/quantum/split_common/split_util.c
@@ -77,7 +77,11 @@ __attribute__((weak)) bool is_keyboard_left(void) {
 #if defined(SPLIT_HAND_PIN)
     // Test pin SPLIT_HAND_PIN for High/Low, if low it's right hand
     setPinInput(SPLIT_HAND_PIN);
+#    ifdef SPLIT_HAND_PIN_LOW_IS_LEFT
+    return !readPin(SPLIT_HAND_PIN);
+#    else
     return readPin(SPLIT_HAND_PIN);
+#    endif
 #elif defined(SPLIT_HAND_MATRIX_GRID)
 #    ifdef SPLIT_HAND_MATRIX_GRID_LOW_IS_RIGHT
     return peek_matrix_intersection(SPLIT_HAND_MATRIX_GRID);