5 files changed, 123 insertions, 21 deletions

diff --git a/docs/config_options.md b/docs/config_options.md
index 78c1f70fd..94f99e74c 100644
--- a/docs/config_options.md
+++ b/docs/config_options.md
@@ -343,6 +343,12 @@ There are a few different ways to set handedness for split keyboards (listed in
 * `#define SPLIT_WPM_ENABLE`
   * Ensures the current WPM is available on the slave when using the QMK-provided split transport.
 
+* `#define SPLIT_OLED_ENABLE`
+  * Syncs the on/off state of the OLED between the halves.
+
+* `#define SPLIT_ST7565_ENABLE`
+  * Syncs the on/off state of the ST7565 screen between the halves.
+
 * `#define SPLIT_TRANSACTION_IDS_KB .....`
 * `#define SPLIT_TRANSACTION_IDS_USER .....`
   * Allows for custom data sync with the slave when using the QMK-provided split transport. See [custom data sync between sides](feature_split_keyboard.md#custom-data-sync) for more information.
diff --git a/docs/feature_split_keyboard.md b/docs/feature_split_keyboard.md
index 428d581ca..a84d38460 100644
--- a/docs/feature_split_keyboard.md
+++ b/docs/feature_split_keyboard.md
@@ -233,6 +233,18 @@ This enables transmitting modifier state (normal, weak and oneshot) to the non p
 
 This enables transmitting the current WPM to the slave side of the split keyboard. The purpose of this feature is to support cosmetic use of WPM (e.g. displaying the current value on an OLED screen). This adds overhead to the split communication protocol and may negatively impact the matrix scan speed when enabled. 
 
+```c
+#define SPLIT_OLED_ENABLE
+```
+
+This enables transmitting the current OLED on/off status to the slave side of the split keyboard. The purpose of this feature is to support state (on/off state only) syncing. This adds overhead to the split communication protocol and may negatively impact the matrix scan speed when enabled. 
+
+```c
+#define SPLIT_ST7565_ENABLE
+```
+
+This enables transmitting the current ST7565 on/off status to the slave side of the split keyboard. The purpose of this feature is to support state (on/off state only) syncing. This adds overhead to the split communication protocol and may negatively impact the matrix scan speed when enabled. 
+
 ### Custom data sync between sides :id=custom-data-sync
 
 QMK's split transport allows for arbitrary data transactions at both the keyboard and user levels. This is modelled on a remote procedure call, with the master invoking a function on the slave side, with the ability to send data from master to slave, process it slave side, and send data back from slave to master.
diff --git a/quantum/split_common/transaction_id_define.h b/quantum/split_common/transaction_id_define.h
index 464c73478..3b78402d4 100644
--- a/quantum/split_common/transaction_id_define.h
+++ b/quantum/split_common/transaction_id_define.h
@@ -70,6 +70,14 @@ enum serial_transaction_id {
     PUT_WPM,
 #endif  // defined(WPM_ENABLE) && defined(SPLIT_WPM_ENABLE)
 
+#if defined(OLED_ENABLE) && defined(SPLIT_OLED_ENABLE)
+    PUT_OLED,
+#endif  // defined(WPM_ENABLE) && defined(SPLIT_OLED_ENABLE)
+
+#if defined(ST7565_ENABLE) && defined(SPLIT_ST7565_ENABLE)
+    PUT_ST7565,
+#endif  // defined(ST7565_ENABLE) && defined(SPLIT_ST7565_ENABLE)
+
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
     PUT_RPC_INFO,
     PUT_RPC_REQ_DATA,
diff --git a/quantum/split_common/transactions.c b/quantum/split_common/transactions.c
index abad626e0..de42882df 100644
--- a/quantum/split_common/transactions.c
+++ b/quantum/split_common/transactions.c
@@ -41,8 +41,8 @@
     { &dummy, 0, 0, sizeof_member(split_shared_memory_t, member), offsetof(split_shared_memory_t, member), cb }
 #define trans_target2initiator_initializer(member) trans_target2initiator_initializer_cb(member, NULL)
 
-#define transport_write(id, data, length) transport_execute_transaction(id, data, length, NULL, 0)
-#define transport_read(id, data, length) transport_execute_transaction(id, NULL, 0, data, length)
+#define transport_write(id, data, length)          transport_execute_transaction(id, data, length, NULL, 0)
+#define transport_read(id, data, length)           transport_execute_transaction(id, NULL, 0, data, length)
 
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
 // Forward-declare the RPC callback handlers
@@ -160,8 +160,8 @@ static void master_matrix_handlers_slave(matrix_row_t master_matrix[], matrix_ro
     memcpy(master_matrix, split_shmem->mmatrix.matrix, sizeof(split_shmem->mmatrix.matrix));
 }
 
-#    define TRANSACTIONS_MASTER_MATRIX_MASTER() TRANSACTION_HANDLER_MASTER(master_matrix_handlers)
-#    define TRANSACTIONS_MASTER_MATRIX_SLAVE() TRANSACTION_HANDLER_SLAVE(master_matrix_handlers)
+#    define TRANSACTIONS_MASTER_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(master_matrix_handlers)
+#    define TRANSACTIONS_MASTER_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(master_matrix_handlers)
 #    define TRANSACTIONS_MASTER_MATRIX_REGISTRATIONS [PUT_MASTER_MATRIX] = trans_initiator2target_initializer(mmatrix.matrix),
 
 #else  // SPLIT_TRANSPORT_MIRROR
@@ -238,8 +238,8 @@ static void sync_timer_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     }
 }
 
-#    define TRANSACTIONS_SYNC_TIMER_MASTER() TRANSACTION_HANDLER_MASTER(sync_timer_handlers)
-#    define TRANSACTIONS_SYNC_TIMER_SLAVE() TRANSACTION_HANDLER_SLAVE(sync_timer_handlers)
+#    define TRANSACTIONS_SYNC_TIMER_MASTER()      TRANSACTION_HANDLER_MASTER(sync_timer_handlers)
+#    define TRANSACTIONS_SYNC_TIMER_SLAVE()       TRANSACTION_HANDLER_SLAVE(sync_timer_handlers)
 #    define TRANSACTIONS_SYNC_TIMER_REGISTRATIONS [PUT_SYNC_TIMER] = trans_initiator2target_initializer(sync_timer),
 
 #else  // DISABLE_SYNC_TIMER
@@ -303,8 +303,8 @@ static void led_state_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     set_split_host_keyboard_leds(split_shmem->led_state);
 }
 
-#    define TRANSACTIONS_LED_STATE_MASTER() TRANSACTION_HANDLER_MASTER(led_state_handlers)
-#    define TRANSACTIONS_LED_STATE_SLAVE() TRANSACTION_HANDLER_SLAVE(led_state_handlers)
+#    define TRANSACTIONS_LED_STATE_MASTER()      TRANSACTION_HANDLER_MASTER(led_state_handlers)
+#    define TRANSACTIONS_LED_STATE_SLAVE()       TRANSACTION_HANDLER_SLAVE(led_state_handlers)
 #    define TRANSACTIONS_LED_STATE_REGISTRATIONS [PUT_LED_STATE] = trans_initiator2target_initializer(led_state),
 
 #else  // SPLIT_LED_STATE_ENABLE
@@ -360,8 +360,8 @@ static void mods_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave
 #    endif
 }
 
-#    define TRANSACTIONS_MODS_MASTER() TRANSACTION_HANDLER_MASTER(mods_handlers)
-#    define TRANSACTIONS_MODS_SLAVE() TRANSACTION_HANDLER_SLAVE(mods_handlers)
+#    define TRANSACTIONS_MODS_MASTER()      TRANSACTION_HANDLER_MASTER(mods_handlers)
+#    define TRANSACTIONS_MODS_SLAVE()       TRANSACTION_HANDLER_SLAVE(mods_handlers)
 #    define TRANSACTIONS_MODS_REGISTRATIONS [PUT_MODS] = trans_initiator2target_initializer(mods),
 
 #else  // SPLIT_MODS_ENABLE
@@ -385,8 +385,8 @@ static bool backlight_handlers_master(matrix_row_t master_matrix[], matrix_row_t
 
 static void backlight_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) { backlight_set(split_shmem->backlight_level); }
 
-#    define TRANSACTIONS_BACKLIGHT_MASTER() TRANSACTION_HANDLER_MASTER(backlight_handlers)
-#    define TRANSACTIONS_BACKLIGHT_SLAVE() TRANSACTION_HANDLER_SLAVE(backlight_handlers)
+#    define TRANSACTIONS_BACKLIGHT_MASTER()      TRANSACTION_HANDLER_MASTER(backlight_handlers)
+#    define TRANSACTIONS_BACKLIGHT_SLAVE()       TRANSACTION_HANDLER_SLAVE(backlight_handlers)
 #    define TRANSACTIONS_BACKLIGHT_REGISTRATIONS [PUT_BACKLIGHT] = trans_initiator2target_initializer(backlight_level),
 
 #else  // BACKLIGHT_ENABLE
@@ -422,8 +422,8 @@ static void rgblight_handlers_slave(matrix_row_t master_matrix[], matrix_row_t s
     }
 }
 
-#    define TRANSACTIONS_RGBLIGHT_MASTER() TRANSACTION_HANDLER_MASTER(rgblight_handlers)
-#    define TRANSACTIONS_RGBLIGHT_SLAVE() TRANSACTION_HANDLER_SLAVE(rgblight_handlers)
+#    define TRANSACTIONS_RGBLIGHT_MASTER()      TRANSACTION_HANDLER_MASTER(rgblight_handlers)
+#    define TRANSACTIONS_RGBLIGHT_SLAVE()       TRANSACTION_HANDLER_SLAVE(rgblight_handlers)
 #    define TRANSACTIONS_RGBLIGHT_REGISTRATIONS [PUT_RGBLIGHT] = trans_initiator2target_initializer(rgblight_sync),
 
 #else  // defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
@@ -452,8 +452,8 @@ static void led_matrix_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     led_matrix_set_suspend_state(split_shmem->led_matrix_sync.led_suspend_state);
 }
 
-#    define TRANSACTIONS_LED_MATRIX_MASTER() TRANSACTION_HANDLER_MASTER(led_matrix_handlers)
-#    define TRANSACTIONS_LED_MATRIX_SLAVE() TRANSACTION_HANDLER_SLAVE(led_matrix_handlers)
+#    define TRANSACTIONS_LED_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(led_matrix_handlers)
+#    define TRANSACTIONS_LED_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(led_matrix_handlers)
 #    define TRANSACTIONS_LED_MATRIX_REGISTRATIONS [PUT_LED_MATRIX] = trans_initiator2target_initializer(led_matrix_sync),
 
 #else  // defined(LED_MATRIX_ENABLE) && defined(LED_MATRIX_SPLIT)
@@ -482,8 +482,8 @@ static void rgb_matrix_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     rgb_matrix_set_suspend_state(split_shmem->rgb_matrix_sync.rgb_suspend_state);
 }
 
-#    define TRANSACTIONS_RGB_MATRIX_MASTER() TRANSACTION_HANDLER_MASTER(rgb_matrix_handlers)
-#    define TRANSACTIONS_RGB_MATRIX_SLAVE() TRANSACTION_HANDLER_SLAVE(rgb_matrix_handlers)
+#    define TRANSACTIONS_RGB_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(rgb_matrix_handlers)
+#    define TRANSACTIONS_RGB_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(rgb_matrix_handlers)
 #    define TRANSACTIONS_RGB_MATRIX_REGISTRATIONS [PUT_RGB_MATRIX] = trans_initiator2target_initializer(rgb_matrix_sync),
 
 #else  // defined(RGB_MATRIX_ENABLE) && defined(RGB_MATRIX_SPLIT)
@@ -507,8 +507,8 @@ static bool wpm_handlers_master(matrix_row_t master_matrix[], matrix_row_t slave
 
 static void wpm_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) { set_current_wpm(split_shmem->current_wpm); }
 
-#    define TRANSACTIONS_WPM_MASTER() TRANSACTION_HANDLER_MASTER(wpm_handlers)
-#    define TRANSACTIONS_WPM_SLAVE() TRANSACTION_HANDLER_SLAVE(wpm_handlers)
+#    define TRANSACTIONS_WPM_MASTER()      TRANSACTION_HANDLER_MASTER(wpm_handlers)
+#    define TRANSACTIONS_WPM_SLAVE()       TRANSACTION_HANDLER_SLAVE(wpm_handlers)
 #    define TRANSACTIONS_WPM_REGISTRATIONS [PUT_WPM] = trans_initiator2target_initializer(current_wpm),
 
 #else  // defined(WPM_ENABLE) && defined(SPLIT_WPM_ENABLE)
@@ -520,6 +520,68 @@ static void wpm_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_
 #endif  // defined(WPM_ENABLE) && defined(SPLIT_WPM_ENABLE)
 
 ////////////////////////////////////////////////////
+// OLED
+
+#if defined(OLED_ENABLE) && defined(SPLIT_OLED_ENABLE)
+
+static bool oled_handlers_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    static uint32_t last_update        = 0;
+    bool            current_oled_state = is_oled_on();
+    return send_if_condition(PUT_OLED, &last_update, (current_oled_state != split_shmem->current_oled_state), &current_oled_state, sizeof(current_oled_state));
+}
+
+static void oled_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    if (split_shmem->current_oled_state) {
+        oled_on();
+    } else {
+        oled_off();
+    }
+}
+
+#    define TRANSACTIONS_OLED_MASTER()      TRANSACTION_HANDLER_MASTER(oled_handlers)
+#    define TRANSACTIONS_OLED_SLAVE()       TRANSACTION_HANDLER_SLAVE(oled_handlers)
+#    define TRANSACTIONS_OLED_REGISTRATIONS [PUT_OLED] = trans_initiator2target_initializer(current_oled_state),
+
+#else  // defined(OLED_ENABLE) && defined(SPLIT_OLED_ENABLE)
+
+#    define TRANSACTIONS_OLED_MASTER()
+#    define TRANSACTIONS_OLED_SLAVE()
+#    define TRANSACTIONS_OLED_REGISTRATIONS
+
+#endif  // defined(OLED_ENABLE) && defined(SPLIT_OLED_ENABLE)
+
+////////////////////////////////////////////////////
+// ST7565
+
+#if defined(ST7565_ENABLE) && defined(SPLIT_ST7565_ENABLE)
+
+static bool st7565_handlers_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    static uint32_t last_update          = 0;
+    bool            current_st7565_state = st7565_is_on();
+    return send_if_condition(PUT_ST7565, &last_update, (current_st7565_state != split_shmem->current_st7565_state), &current_st7565_state, sizeof(current_st7565_state));
+}
+
+static void st7565_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    if (split_shmem->current_st7565_state) {
+        st7565_on();
+    } else {
+        st7565_off();
+    }
+}
+
+#    define TRANSACTIONS_ST7565_MASTER()      TRANSACTION_HANDLER_MASTER(st7565_handlers)
+#    define TRANSACTIONS_ST7565_SLAVE()       TRANSACTION_HANDLER_SLAVE(st7565_handlers)
+#    define TRANSACTIONS_ST7565_REGISTRATIONS [PUT_ST7565] = trans_initiator2target_initializer(current_st7565_state),
+
+#else  // defined(ST7565_ENABLE) && defined(SPLIT_ST7565_ENABLE)
+
+#    define TRANSACTIONS_ST7565_MASTER()
+#    define TRANSACTIONS_ST7565_SLAVE()
+#    define TRANSACTIONS_ST7565_REGISTRATIONS
+
+#endif  // defined(ST7565_ENABLE) && defined(SPLIT_ST7565_ENABLE)
+
+////////////////////////////////////////////////////
 
 uint8_t                  dummy;
 split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
@@ -543,6 +605,8 @@ split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
     TRANSACTIONS_LED_MATRIX_REGISTRATIONS
     TRANSACTIONS_RGB_MATRIX_REGISTRATIONS
     TRANSACTIONS_WPM_REGISTRATIONS
+    TRANSACTIONS_OLED_REGISTRATIONS
+    TRANSACTIONS_ST7565_REGISTRATIONS
 // clang-format on
 
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
@@ -567,6 +631,8 @@ bool transactions_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix
     TRANSACTIONS_LED_MATRIX_MASTER();
     TRANSACTIONS_RGB_MATRIX_MASTER();
     TRANSACTIONS_WPM_MASTER();
+    TRANSACTIONS_OLED_MASTER();
+    TRANSACTIONS_ST7565_MASTER();
     return okay;
 }
 
@@ -583,6 +649,8 @@ void transactions_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[
     TRANSACTIONS_LED_MATRIX_SLAVE();
     TRANSACTIONS_RGB_MATRIX_SLAVE();
     TRANSACTIONS_WPM_SLAVE();
+    TRANSACTIONS_OLED_SLAVE();
+    TRANSACTIONS_ST7565_SLAVE();
 }
 
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
diff --git a/quantum/split_common/transport.h b/quantum/split_common/transport.h
index 2e07f6b25..1d4f6ed0c 100644
--- a/quantum/split_common/transport.h
+++ b/quantum/split_common/transport.h
@@ -165,6 +165,14 @@ typedef struct _split_shared_memory_t {
     uint8_t current_wpm;
 #endif  // defined(WPM_ENABLE) && defined(SPLIT_WPM_ENABLE)
 
+#if defined(OLED_ENABLE) && defined(SPLIT_OLED_ENABLE)
+    uint8_t current_oled_state;
+#endif  // defined(OLED_ENABLE) && defined(SPLIT_OLED_ENABLE)
+
+#if defined(ST7565_ENABLE) && defined(SPLIT_ST7565_ENABLE)
+    uint8_t current_st7565_state;
+#endif  // ST7565_ENABLE(OLED_ENABLE) && defined(SPLIT_ST7565_ENABLE)
+
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
     rpc_sync_info_t rpc_info;
     uint8_t         rpc_m2s_buffer[RPC_M2S_BUFFER_SIZE];
@@ -172,4 +180,4 @@ typedef struct _split_shared_memory_t {
 #endif  // defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
 } split_shared_memory_t;
 
-extern split_shared_memory_t *const split_shmem;
\ No newline at end of file
+extern split_shared_memory_t *const split_shmem;