Shorter paths to HAL, ExtUI (#17156)

Marlin/src/HAL/SAMD51/watchdog.h

@@ -0,0 +1,31 @@
+/**
+ * Marlin 3D Printer Firmware
+ *
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ * SAMD51 HAL developed by Giuliano Zaro (AKA GMagician)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+// Initialize watchdog with a 4 second interrupt time
+void watchdog_init();
+
+// Reset watchdog. MUST be called at least every 4 seconds after the
+// first watchdog_init or SAMD will go into emergency procedures.
+inline void HAL_watchdog_refresh() {
+  SYNC(WDT->SYNCBUSY.bit.CLEAR);        // Test first if previous is 'ongoing' to save time waiting for command execution
+  WDT->CLEAR.reg = WDT_CLEAR_CLEAR_KEY;
+}