Initial public release of WII5 Buoy firmware

Firmware for an autonomous wave-measurement buoy (ATmega2560-based
WII5 v2 board). Reads wave motion from a Sparton AHRS-M1/M2 IMU,
samples GPS and battery state, and reports back over Iridium SBD
satellite telemetry. Originally developed 2012-2024.

This is the first public release. Code, documentation, and field-tested
operating modes (Capture, Sleep, Position, ManualTest, SelfTest,
LowBattery) are licensed under Apache 2.0 — see LICENSE and NOTICE.

See README.md for an overview and build instructions, CONTRIBUTING.md
for how to contribute, and DEPLOYMENTS.md for the field-deployment log.

WII5SerialDebug.cpp

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (c) 2012-2024 Scott Penrose <scottp@dd.com.au> and WII5 Buoy contributors
+//
+// This file is part of WII5 Buoy firmware.
+// See LICENSE for full terms.
+
+/**
+ * @file WII5SerialDebug.cpp
+ * @brief Optional debug-serial port (SoftwareSerial) — gated on WII5_DEBUG_SERIAL.
+ */
+
+#include <WII5.h>
+#include <WII5SerialDebug.h>
+
+#ifdef WII5_DEBUG_SERIAL
+SoftwareSerial SerialDebug(WII5_DEBUG_SERIAL_RX, WII5_DEBUG_SERIAL_TX);
+#endif