Massdrop keyboard updates for SEND_STRING, syscalls, stdio, debug prints, Auto Shift (#3973)

* Update for SEND_STRING usage

Update for SEND_STRING usage.
Sending keyboard reports (kbd, nkro) now obey the minimum polling time.
While attempting to send a keyboard report and waiting for a USB poll, other functions of the keyboard, including LED effects and power management, will continue to operate at their intended intervals.

* Updates for send string, syscalls, stdio, debug prints, auto shift

Now properly waiting for previous keys sent over USB to complete before sending new.
Added heap to linker and now compiling with syscalls support.
Removed custom string functions and now using stdio.
dprintf now works as intended through virtser device.

* CTRL and ALT keymap updates

CTRL mac keymap updated
ALT default and mac keymap updated
ALT rules.mk added Auto Shift with default no

* Code cleanup as per discussion with vomindoraan

Code cleanup as per discussion with vomindoraan

22 files changed, 175 insertions, 520 deletions

diff --git a/keyboards/massdrop/alt/alt.h b/keyboards/massdrop/alt/alt.h
index 387985512b..8dfed8d2d6 100644
--- a/keyboards/massdrop/alt/alt.h
+++ b/keyboards/massdrop/alt/alt.h
@@ -22,3 +22,13 @@
     {   K45, KC_NO,   K46,   K47,   K48,   K49,   K50,   K51,   K52,   K53,   K54,   K55,   K56,   K57,   K58, }, \
     {   K59,   K60,   K61, KC_NO, KC_NO, KC_NO,   K62, KC_NO, KC_NO, KC_NO,   K63,   K64,   K65,   K66,   K67, }, \
 }
+
+#define TOGGLE_FLAG_AND_PRINT(var, name) { \
+        if (var) { \
+            dprintf(name " disabled\r\n"); \
+            var = !var; \
+        } else { \
+            var = !var; \
+            dprintf(name " enabled\r\n"); \
+        } \
+    }
diff --git a/keyboards/massdrop/alt/keymaps/default/keymap.c b/keyboards/massdrop/alt/keymaps/default/keymap.c
index 0cbce86293..a5c443ffcd 100644
--- a/keyboards/massdrop/alt/keymaps/default/keymap.c
+++ b/keyboards/massdrop/alt/keymaps/default/keymap.c
@@ -136,8 +136,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         case L_T_BR:
             if (record->event.pressed) {
                 led_animation_breathing = !led_animation_breathing;
-                if (led_animation_breathing)
-                {
+                if (led_animation_breathing) {
                     gcr_breathe = gcr_desired;
                     led_animation_breathe_cur = BREATHE_MIN_STEP;
                     breathe_dir = 1;
@@ -151,50 +150,32 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
             return false;
         case U_T_AUTO:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_extra_manual = !usb_extra_manual;
-                CDC_print("USB extra port manual mode ");
-                CDC_print(usb_extra_manual ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_extra_manual, "USB extra port manual mode");
             }
             return false;
         case U_T_AGCR:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_gcr_auto = !usb_gcr_auto;
-                CDC_print("USB GCR auto mode ");
-                CDC_print(usb_gcr_auto ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_gcr_auto, "USB GCR auto mode");
             }
             return false;
         case DBG_TOG:
             if (record->event.pressed) {
-                debug_enable = !debug_enable;
-                CDC_print("Debug mode ");
-                CDC_print(debug_enable ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_enable, "Debug mode");
             }
             return false;
         case DBG_MTRX:
             if (record->event.pressed) {
-                debug_matrix = !debug_matrix;
-                CDC_print("Debug matrix ");
-                CDC_print(debug_matrix ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_matrix, "Debug matrix");
             }
             return false;
         case DBG_KBD:
             if (record->event.pressed) {
-                debug_keyboard = !debug_keyboard;
-                CDC_print("Debug keyboard ");
-                CDC_print(debug_keyboard ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_keyboard, "Debug keyboard");
             }
             return false;
         case DBG_MOU:
             if (record->event.pressed) {
-                debug_mouse = !debug_mouse;
-                CDC_print("Debug mouse ");
-                CDC_print(debug_mouse ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_mouse, "Debug mouse");
             }
             return false;
         case MD_BOOT:
@@ -209,4 +190,4 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         default:
             return true; //Process all other keycodes normally
     }
-}
\ No newline at end of file
+}
diff --git a/keyboards/massdrop/alt/keymaps/mac/keymap.c b/keyboards/massdrop/alt/keymaps/mac/keymap.c
index e886290e7e..d6978fd801 100644
--- a/keyboards/massdrop/alt/keymaps/mac/keymap.c
+++ b/keyboards/massdrop/alt/keymaps/mac/keymap.c
@@ -136,8 +136,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         case L_T_BR:
             if (record->event.pressed) {
                 led_animation_breathing = !led_animation_breathing;
-                if (led_animation_breathing)
-                {
+                if (led_animation_breathing) {
                     gcr_breathe = gcr_desired;
                     led_animation_breathe_cur = BREATHE_MIN_STEP;
                     breathe_dir = 1;
@@ -151,50 +150,32 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
             return false;
         case U_T_AUTO:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_extra_manual = !usb_extra_manual;
-                CDC_print("USB extra port manual mode ");
-                CDC_print(usb_extra_manual ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_extra_manual, "USB extra port manual mode");
             }
             return false;
         case U_T_AGCR:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_gcr_auto = !usb_gcr_auto;
-                CDC_print("USB GCR auto mode ");
-                CDC_print(usb_gcr_auto ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_gcr_auto, "USB GCR auto mode");
             }
             return false;
         case DBG_TOG:
             if (record->event.pressed) {
-                debug_enable = !debug_enable;
-                CDC_print("Debug mode ");
-                CDC_print(debug_enable ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_enable, "Debug mode");
             }
             return false;
         case DBG_MTRX:
             if (record->event.pressed) {
-                debug_matrix = !debug_matrix;
-                CDC_print("Debug matrix ");
-                CDC_print(debug_matrix ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_matrix, "Debug matrix");
             }
             return false;
         case DBG_KBD:
             if (record->event.pressed) {
-                debug_keyboard = !debug_keyboard;
-                CDC_print("Debug keyboard ");
-                CDC_print(debug_keyboard ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_keyboard, "Debug keyboard");
             }
             return false;
         case DBG_MOU:
             if (record->event.pressed) {
-                debug_mouse = !debug_mouse;
-                CDC_print("Debug mouse ");
-                CDC_print(debug_mouse ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_mouse, "Debug mouse");
             }
             return false;
         case MD_BOOT:
diff --git a/keyboards/massdrop/alt/rules.mk b/keyboards/massdrop/alt/rules.mk
index daf6795852..c5539158f5 100644
--- a/keyboards/massdrop/alt/rules.mk
+++ b/keyboards/massdrop/alt/rules.mk
@@ -30,3 +30,4 @@ FAUXCLICKY_ENABLE = no      # Use buzzer to emulate clicky switches
 HD44780_ENABLE = no         # Enable support for HD44780 based LCDs (+400)
 VIRTSER_ENABLE = no         # USB Serial Driver
 RAW_ENABLE = no             # Raw device
+AUTO_SHIFT_ENABLE = no      # Auto Shift
diff --git a/keyboards/massdrop/ctrl/ctrl.h b/keyboards/massdrop/ctrl/ctrl.h
index dc7c7eabe5..c83efca16d 100644
--- a/keyboards/massdrop/ctrl/ctrl.h
+++ b/keyboards/massdrop/ctrl/ctrl.h
@@ -30,3 +30,13 @@
     {   K59, K60, K61, K62, K63, K76, K50, K33   }, \
     {   K72, K73, K74, K75, K85, K86, K87,       }, \
 }
+
+#define TOGGLE_FLAG_AND_PRINT(var, name) { \
+        if (var) { \
+            dprintf(name " disabled\r\n"); \
+            var = !var; \
+        } else { \
+            var = !var; \
+            dprintf(name " enabled\r\n"); \
+        } \
+    }
diff --git a/keyboards/massdrop/ctrl/keymaps/default/keymap.c b/keyboards/massdrop/ctrl/keymaps/default/keymap.c
index 9bfb7fec58..88c1ac3123 100644
--- a/keyboards/massdrop/ctrl/keymaps/default/keymap.c
+++ b/keyboards/massdrop/ctrl/keymaps/default/keymap.c
@@ -33,7 +33,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         KC_TAB,  KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,    KC_Y,    KC_U,    KC_I,    KC_O,    KC_P,    KC_LBRC, KC_RBRC, KC_BSLS,   KC_DEL,  KC_END,  KC_PGDN, \
         KC_CAPS, KC_A,    KC_S,    KC_D,    KC_F,    KC_G,    KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN, KC_QUOT, KC_ENT, \
         KC_LSFT, KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,    KC_N,    KC_M,    KC_COMM, KC_DOT,  KC_SLSH, KC_RSFT,                              KC_UP, \
-        KC_LCTL, KC_LGUI, KC_LALT,                  KC_SPC,                              KC_RALT, MO(1),   KC_APP,  KC_RCTL,            KC_LEFT, KC_DOWN, KC_RGHT \
+        KC_LCTL, KC_LGUI, KC_LALT,                   KC_SPC,                             KC_RALT, MO(1),   KC_APP,  KC_RCTL,            KC_LEFT, KC_DOWN, KC_RGHT \
     ),
     [1] = LAYOUT(
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_MUTE, KC_TRNS, KC_TRNS, \
@@ -41,7 +41,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         L_T_BR,  L_PSD,   L_BRI,   L_PSI,   KC_TRNS, KC_TRNS, KC_TRNS, U_T_AUTO,U_T_AGCR,KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,   KC_MPRV, KC_MNXT, KC_VOLD, \
         L_T_PTD, L_PTP,   L_BRD,   L_PTN,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, \
         KC_TRNS, L_T_MD,  L_T_ONF, KC_TRNS, KC_TRNS, MD_BOOT, TG_NKRO, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,                              KC_TRNS, \
-        KC_TRNS, KC_TRNS, KC_TRNS,                  KC_TRNS,                             KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
+        KC_TRNS, KC_TRNS, KC_TRNS,                   KC_TRNS,                            KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
     ),
     /*
     [X] = LAYOUT(
@@ -50,7 +50,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS, \
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, \
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, TG_NKRO, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,                              KC_TRNS, \
-        KC_TRNS, KC_TRNS, KC_TRNS,                  KC_TRNS,                             KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
+        KC_TRNS, KC_TRNS, KC_TRNS,                   KC_TRNS,                            KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
     ),
     */
 };
@@ -139,8 +139,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         case L_T_BR:
             if (record->event.pressed) {
                 led_animation_breathing = !led_animation_breathing;
-                if (led_animation_breathing)
-                {
+                if (led_animation_breathing) {
                     gcr_breathe = gcr_desired;
                     led_animation_breathe_cur = BREATHE_MIN_STEP;
                     breathe_dir = 1;
@@ -154,50 +153,32 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
             return false;
         case U_T_AUTO:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_extra_manual = !usb_extra_manual;
-                CDC_print("USB extra port manual mode ");
-                CDC_print(usb_extra_manual ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_extra_manual, "USB extra port manual mode");
             }
             return false;
         case U_T_AGCR:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_gcr_auto = !usb_gcr_auto;
-                CDC_print("USB GCR auto mode ");
-                CDC_print(usb_gcr_auto ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_gcr_auto, "USB GCR auto mode");
             }
             return false;
         case DBG_TOG:
             if (record->event.pressed) {
-                debug_enable = !debug_enable;
-                CDC_print("Debug mode ");
-                CDC_print(debug_enable ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_enable, "Debug mode");
             }
             return false;
         case DBG_MTRX:
             if (record->event.pressed) {
-                debug_matrix = !debug_matrix;
-                CDC_print("Debug matrix ");
-                CDC_print(debug_matrix ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_matrix, "Debug matrix");
             }
             return false;
         case DBG_KBD:
             if (record->event.pressed) {
-                debug_keyboard = !debug_keyboard;
-                CDC_print("Debug keyboard ");
-                CDC_print(debug_keyboard ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_keyboard, "Debug keyboard");
             }
             return false;
         case DBG_MOU:
             if (record->event.pressed) {
-                debug_mouse = !debug_mouse;
-                CDC_print("Debug mouse ");
-                CDC_print(debug_mouse ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_mouse, "Debug mouse");
             }
             return false;
         case MD_BOOT:
diff --git a/keyboards/massdrop/ctrl/keymaps/mac/keymap.c b/keyboards/massdrop/ctrl/keymaps/mac/keymap.c
index a03f891e8c..6c5dfe19c0 100644
--- a/keyboards/massdrop/ctrl/keymaps/mac/keymap.c
+++ b/keyboards/massdrop/ctrl/keymaps/mac/keymap.c
@@ -33,15 +33,15 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         KC_TAB,  KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,    KC_Y,    KC_U,    KC_I,    KC_O,    KC_P,    KC_LBRC, KC_RBRC, KC_BSLS,   KC_DEL,  KC_END,  KC_PGDN, \
         KC_CAPS, KC_A,    KC_S,    KC_D,    KC_F,    KC_G,    KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN, KC_QUOT, KC_ENT, \
         KC_LSFT, KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,    KC_N,    KC_M,    KC_COMM, KC_DOT,  KC_SLSH, KC_RSFT,                              KC_UP, \
-        KC_LCTL, KC_LALT, KC_LGUI,                  KC_SPC,                              KC_RGUI, MO(1),   KC_APP,  KC_RCTL,            KC_LEFT, KC_DOWN, KC_RGHT \
+        KC_LCTL, KC_LALT, KC_LGUI,                   KC_SPC,                             KC_RGUI, MO(1),   KC_APP,  KC_RCTL,            KC_LEFT, KC_DOWN, KC_RGHT \
     ),
     [1] = LAYOUT(
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_MUTE, KC_TRNS, KC_TRNS, \
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,   KC_MPLY, KC_MSTP, KC_VOLU, \
         L_T_BR,  L_PSD,   L_BRI,   L_PSI,   KC_TRNS, KC_TRNS, KC_TRNS, U_T_AUTO,U_T_AGCR,KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,   KC_MPRV, KC_MNXT, KC_VOLD, \
         L_T_PTD, L_PTP,   L_BRD,   L_PTN,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, \
-        KC_TRNS, L_T_MD,  L_T_ONF, KC_TRNS, KC_TRNS, KC_TRNS, TG_NKRO, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,                              KC_TRNS, \
-        KC_TRNS, KC_TRNS, KC_TRNS,                  KC_TRNS,                             KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
+        KC_TRNS, L_T_MD,  L_T_ONF, KC_TRNS, KC_TRNS, MD_BOOT, TG_NKRO, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,                              KC_TRNS, \
+        KC_TRNS, KC_TRNS, KC_TRNS,                   KC_TRNS,                            KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
     ),
     /*
     [X] = LAYOUT(
@@ -50,7 +50,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS, \
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, \
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, TG_NKRO, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,                              KC_TRNS, \
-        KC_TRNS, KC_TRNS, KC_TRNS,                  KC_TRNS,                             KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
+        KC_TRNS, KC_TRNS, KC_TRNS,                   KC_TRNS,                            KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,            KC_TRNS, KC_TRNS, KC_TRNS \
     ),
     */
 };
@@ -139,8 +139,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         case L_T_BR:
             if (record->event.pressed) {
                 led_animation_breathing = !led_animation_breathing;
-                if (led_animation_breathing)
-                {
+                if (led_animation_breathing) {
                     gcr_breathe = gcr_desired;
                     led_animation_breathe_cur = BREATHE_MIN_STEP;
                     breathe_dir = 1;
@@ -154,50 +153,32 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
             return false;
         case U_T_AUTO:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_extra_manual = !usb_extra_manual;
-                CDC_print("USB extra port manual mode ");
-                CDC_print(usb_extra_manual ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_extra_manual, "USB extra port manual mode");
             }
             return false;
         case U_T_AGCR:
             if (record->event.pressed && MODS_SHIFT && MODS_CTRL) {
-                usb_gcr_auto = !usb_gcr_auto;
-                CDC_print("USB GCR auto mode ");
-                CDC_print(usb_gcr_auto ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(usb_gcr_auto, "USB GCR auto mode");
             }
             return false;
         case DBG_TOG:
             if (record->event.pressed) {
-                debug_enable = !debug_enable;
-                CDC_print("Debug mode ");
-                CDC_print(debug_enable ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_enable, "Debug mode");
             }
             return false;
         case DBG_MTRX:
             if (record->event.pressed) {
-                debug_matrix = !debug_matrix;
-                CDC_print("Debug matrix ");
-                CDC_print(debug_matrix ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_matrix, "Debug matrix");
             }
             return false;
         case DBG_KBD:
             if (record->event.pressed) {
-                debug_keyboard = !debug_keyboard;
-                CDC_print("Debug keyboard ");
-                CDC_print(debug_keyboard ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_keyboard, "Debug keyboard");
             }
             return false;
         case DBG_MOU:
             if (record->event.pressed) {
-                debug_mouse = !debug_mouse;
-                CDC_print("Debug mouse ");
-                CDC_print(debug_mouse ? "enabled" : "disabled");
-                CDC_print("\r\n");
+                TOGGLE_FLAG_AND_PRINT(debug_mouse, "Debug mouse");
             }
             return false;
         case MD_BOOT:
diff --git a/keyboards/massdrop/ctrl/rules.mk b/keyboards/massdrop/ctrl/rules.mk
index daf6795852..c5539158f5 100644
--- a/keyboards/massdrop/ctrl/rules.mk
+++ b/keyboards/massdrop/ctrl/rules.mk
@@ -30,3 +30,4 @@ FAUXCLICKY_ENABLE = no      # Use buzzer to emulate clicky switches
 HD44780_ENABLE = no         # Enable support for HD44780 based LCDs (+400)
 VIRTSER_ENABLE = no         # USB Serial Driver
 RAW_ENABLE = no             # Raw device
+AUTO_SHIFT_ENABLE = no      # Auto Shift
diff --git a/lib/arm_atsam/packs/atmel/SAMD51_DFP/1.0.70/gcc/gcc/samd51j18a_flash.ld b/lib/arm_atsam/packs/atmel/SAMD51_DFP/1.0.70/gcc/gcc/samd51j18a_flash.ld
index 3d114f5b7b..35db619717 100644
--- a/lib/arm_atsam/packs/atmel/SAMD51_DFP/1.0.70/gcc/gcc/samd51j18a_flash.ld
+++ b/lib/arm_atsam/packs/atmel/SAMD51_DFP/1.0.70/gcc/gcc/samd51j18a_flash.ld
@@ -35,7 +35,7 @@ SEARCH_DIR(.)
 /* Memory Spaces Definitions */
 MEMORY
 {
-  //rom      (rx)  : ORIGIN = 0x00000000, LENGTH = 0x00040000
+/*rom      (rx)  : ORIGIN = 0x00000000, LENGTH = 0x00040000*/
   rom      (rx)  : ORIGIN = 0x00004000, LENGTH = 0x0003C000
   ram      (rwx) : ORIGIN = 0x20000000, LENGTH = 0x00020000
   bkupram  (rwx) : ORIGIN = 0x47000000, LENGTH = 0x00002000
@@ -45,6 +45,9 @@ MEMORY
 /* The stack size used by the application. NOTE: you need to adjust according to your application. */
 STACK_SIZE = DEFINED(STACK_SIZE) ? STACK_SIZE : DEFINED(__stack_size__) ? __stack_size__ : 0x8000;
 
+/* The heap size used by the application. */
+HEAP_SIZE = DEFINED(HEAP_SIZE) ? HEAP_SIZE : DEFINED(__heap_size__) ? __heap_size__ : 0x800;
+
 _srom = ORIGIN(rom);
 _lrom = LENGTH(rom);
 _erom = ORIGIN(rom) + LENGTH(rom);
@@ -153,6 +156,17 @@ SECTIONS
         _ezero = .;
     } > ram
 
+    /* .heap section for syscalls */
+    .heap (NOLOAD) :
+    {
+        . = ALIGN(4);
+        _end = .;
+        end = .;
+        _heap_start = .;
+        . = . + HEAP_SIZE;
+        _heap_end = .;
+    } > ram
+
     /* stack section */
     .stack (NOLOAD):
     {
diff --git a/tmk_core/arm_atsam.mk b/tmk_core/arm_atsam.mk
index ef412d59d6..06823fb629 100644
--- a/tmk_core/arm_atsam.mk
+++ b/tmk_core/arm_atsam.mk
@@ -36,7 +36,7 @@ LDFLAGS +=-Wl,--gc-sections
 LDFLAGS += -Wl,-Map="%OUT%%PROJ_NAME%.map"
 LDFLAGS += -Wl,--start-group
 LDFLAGS += -Wl,--end-group
-LDFLAGS += -Wl,--gc-sections
+LDFLAGS += --specs=rdimon.specs
 LDFLAGS += -T$(LIB_PATH)/arm_atsam/packs/atmel/SAMD51_DFP/1.0.70/gcc/gcc/samd51j18a_flash.ld
 
 OPT_DEFS += -DPROTOCOL_ARM_ATSAM
diff --git a/tmk_core/common/arm_atsam/printf.h b/tmk_core/common/arm_atsam/printf.h
index 582c83bf54..3206b40bdb 100644
--- a/tmk_core/common/arm_atsam/printf.h
+++ b/tmk_core/common/arm_atsam/printf.h
@@ -1,8 +1,8 @@
 #ifndef _PRINTF_H_
 #define _PRINTF_H_
 
-#define __xprintf dpf
 int dpf(const char *_Format, ...);
+#define __xprintf dpf
 
 #endif //_PRINTF_H_
 
diff --git a/tmk_core/common/print.h b/tmk_core/common/print.h
index 9cbe67bad6..d945276572 100644
--- a/tmk_core/common/print.h
+++ b/tmk_core/common/print.h
@@ -29,7 +29,7 @@
 #include <stdbool.h>
 #include "util.h"
 
-#if defined(PROTOCOL_CHIBIOS)
+#if defined(PROTOCOL_CHIBIOS) || defined(PROTOCOL_ARM_ATSAM)
 #define PSTR(x) x
 #endif
 
diff --git a/tmk_core/protocol/arm_atsam.mk b/tmk_core/protocol/arm_atsam.mk
index d535b64cd7..04e02790a0 100644
--- a/tmk_core/protocol/arm_atsam.mk
+++ b/tmk_core/protocol/arm_atsam.mk
@@ -10,7 +10,6 @@ SRC += $(ARM_ATSAM_DIR)/spi.c
 SRC += $(ARM_ATSAM_DIR)/startup.c
 
 SRC += $(ARM_ATSAM_DIR)/usb/main_usb.c
-SRC += $(ARM_ATSAM_DIR)/usb/spfssf.c
 SRC += $(ARM_ATSAM_DIR)/usb/udc.c
 SRC += $(ARM_ATSAM_DIR)/usb/udi_cdc.c
 SRC += $(ARM_ATSAM_DIR)/usb/udi_hid.c
diff --git a/tmk_core/protocol/arm_atsam/arm_atsam_protocol.h b/tmk_core/protocol/arm_atsam/arm_atsam_protocol.h
index be73beccd7..2ba0991749 100644
--- a/tmk_core/protocol/arm_atsam/arm_atsam_protocol.h
+++ b/tmk_core/protocol/arm_atsam/arm_atsam_protocol.h
@@ -36,7 +36,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "issi3733_driver.h"
 #include "./usb/compiler.h"
 #include "./usb/udc.h"
-#include "./usb/spfssf.h"
 #include "./usb/udi_cdc.h"
 
 #endif //MD_BOOTLOADER
diff --git a/tmk_core/protocol/arm_atsam/d51_util.h b/tmk_core/protocol/arm_atsam/d51_util.h
index 465889c7cb..7a35f7989f 100644
--- a/tmk_core/protocol/arm_atsam/d51_util.h
+++ b/tmk_core/protocol/arm_atsam/d51_util.h
@@ -32,6 +32,16 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define m15_on  REG_PORT_OUTSET1 = 0x40000000 //PB30 High
 #define m15_off REG_PORT_OUTCLR1 = 0x40000000 //PB30 Low
 
+//Debug Port PB23
+#define m27_ena REG_PORT_DIRSET1 = 0x800000 //PB23 Output
+#define m27_on  REG_PORT_OUTSET1 = 0x800000 //PB23 High
+#define m27_off REG_PORT_OUTCLR1 = 0x800000 //PB23 Low
+
+//Debug Port PB31
+#define m28_ena REG_PORT_DIRSET1 = 0x80000000 //PB31 Output
+#define m28_on  REG_PORT_OUTSET1 = 0x80000000 //PB31 High
+#define m28_off REG_PORT_OUTCLR1 = 0x80000000 //PB31 Low
+
 #define m15_loop(M15X) {uint8_t M15L=M15X; while(M15L--){m15_on;CLK_delay_us(1);m15_off;}}
 
 void m15_print(uint32_t x);
diff --git a/tmk_core/protocol/arm_atsam/main_arm_atsam.c b/tmk_core/protocol/arm_atsam/main_arm_atsam.c
index 8cc7767038..676dac4ea3 100644
--- a/tmk_core/protocol/arm_atsam/main_arm_atsam.c
+++ b/tmk_core/protocol/arm_atsam/main_arm_atsam.c
@@ -31,6 +31,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //From keyboard's directory
 #include "config_led.h"
 
+void main_subtasks(void);
 uint8_t keyboard_leds(void);
 void send_keyboard(report_keyboard_t *report);
 void send_mouse(report_mouse_t *report);
@@ -65,7 +66,7 @@ void send_keyboard(report_keyboard_t *report)
     if (!keymap_config.nkro)
     {
 #endif //NKRO_ENABLE
-        dprint("s-kbd\r\n");
+        while (udi_hid_kbd_b_report_trans_ongoing) { main_subtasks(); } //Run other tasks while waiting for USB to be free
 
         irqflags = __get_PRIMASK();
         __disable_irq();
@@ -81,7 +82,7 @@ void send_keyboard(report_keyboard_t *report)
     }
     else
     {
-        dprint("s-nkro\r\n");
+        while (udi_hid_nkro_b_report_trans_ongoing) { main_subtasks(); } //Run other tasks while waiting for USB to be free
 
         irqflags = __get_PRIMASK();
         __disable_irq();
@@ -102,8 +103,6 @@ void send_mouse(report_mouse_t *report)
 #ifdef MOUSEKEY_ENABLE
     uint32_t irqflags;
 
-    dprint("s-mou\r\n");
-
     irqflags = __get_PRIMASK();
     __disable_irq();
     __DMB();
@@ -120,8 +119,6 @@ void send_mouse(report_mouse_t *report)
 void send_system(uint16_t data)
 {
 #ifdef EXTRAKEY_ENABLE
-    dprintf("s-exks %i\r\n", data);
-
     uint32_t irqflags;
 
     irqflags = __get_PRIMASK();
@@ -142,8 +139,6 @@ void send_system(uint16_t data)
 void send_consumer(uint16_t data)
 {
 #ifdef EXTRAKEY_ENABLE
-    dprintf("s-exkc %i\r\n",data);
-
     uint32_t irqflags;
 
     irqflags = __get_PRIMASK();
@@ -160,6 +155,77 @@ void send_consumer(uint16_t data)
 #endif //EXTRAKEY_ENABLE
 }
 
+uint8_t g_drvid;
+
+void main_subtask_usb_state(void)
+{
+    if (usb_state == USB_STATE_POWERDOWN)
+    {
+        uint32_t timer_led = timer_read32();
+
+        led_on;
+        if (led_enabled)
+        {
+            for (g_drvid = 0; g_drvid < ISSI3733_DRIVER_COUNT; g_drvid++)
+            {
+                I2C3733_Control_Set(0);
+            }
+        }
+        while (usb_state == USB_STATE_POWERDOWN)
+        {
+            if (timer_read32() - timer_led > 1000) led_off; //Good to indicate went to sleep, but only for a second
+        }
+        if (led_enabled)
+        {
+            for (g_drvid = 0; g_drvid < ISSI3733_DRIVER_COUNT; g_drvid++)
+            {
+                I2C3733_Control_Set(1);
+            }
+        }
+        led_off;
+    }
+}
+
+void main_subtask_led(void)
+{
+    led_matrix_task();
+}
+
+void main_subtask_power_check(void)
+{
+    static uint64_t next_5v_checkup = 0;
+
+    if (CLK_get_ms() > next_5v_checkup)
+    {
+        next_5v_checkup = CLK_get_ms() + 5;
+
+        v_5v = adc_get(ADC_5V);
+        v_5v_avg = 0.9 * v_5v_avg + 0.1 * v_5v;
+
+        gcr_compute();
+    }
+}
+
+void main_subtask_usb_extra_device(void)
+{
+    static uint64_t next_usb_checkup = 0;
+
+    if (CLK_get_ms() > next_usb_checkup)
+    {
+        next_usb_checkup = CLK_get_ms() + 10;
+
+        USB_HandleExtraDevice();
+    }
+}
+
+void main_subtasks(void)
+{
+    main_subtask_usb_state();
+    main_subtask_led();
+    main_subtask_power_check();
+    main_subtask_usb_extra_device();
+}
+
 int main(void)
 {
     led_ena;
@@ -201,9 +267,8 @@ int main(void)
 
     i2c_led_q_init();
 
-    uint8_t drvid;
-    for (drvid=0;drvid<ISSI3733_DRIVER_COUNT;drvid++)
-        I2C_LED_Q_ONOFF(drvid); //Queue data
+    for (g_drvid = 0; g_drvid < ISSI3733_DRIVER_COUNT; g_drvid++)
+        I2C_LED_Q_ONOFF(g_drvid); //Queue data
 
     keyboard_setup();
 
@@ -214,8 +279,6 @@ int main(void)
 #ifdef VIRTSER_ENABLE
     uint64_t next_print = 0;
 #endif //VIRTSER_ENABLE
-    uint64_t next_usb_checkup = 0;
-    uint64_t next_5v_checkup = 0;
 
     v_5v_avg = adc_get(ADC_5V);
 
@@ -223,58 +286,15 @@ int main(void)
 
     while (1)
     {
-        if (usb_state == USB_STATE_POWERDOWN)
-        {
-            uint32_t timer_led = timer_read32();
-
-            led_on;
-            if (led_enabled)
-            {
-                for (drvid=0;drvid<ISSI3733_DRIVER_COUNT;drvid++)
-                {
-                    I2C3733_Control_Set(0);
-                }
-            }
-            while (usb_state == USB_STATE_POWERDOWN)
-            {
-                if (timer_read32() - timer_led > 1000) led_off; //Good to indicate went to sleep, but only for a second
-            }
-            if (led_enabled)
-            {
-                for (drvid=0;drvid<ISSI3733_DRIVER_COUNT;drvid++)
-                {
-                    I2C3733_Control_Set(1);
-                }
-            }
-            led_off;
-        }
-
         keyboard_task();
 
-        led_matrix_task();