UA1ZBE Custom Firmware v1.0

Features:
- VFO mode with direct frequency input
- POCSAG decoder (512/1200 baud) with BCH(31,21) correction
- Full-screen Spectrum analyzer
- FM Radio receiver
- RSSI signal indicator overlay
- Custom boot splash (UA1ZBE / POCSAG pager / build date)

Architecture:
- app/mode.c — mode dispatcher (VFO/POCSAG/Spectrum/FM)
- app/boot_splash.c — 2-second boot splash
- app/pocsag/ — POCSAG decoder + BCH correction
- app/display_rssi.c — RSSI indicator
- main.c — entry point with custom init
- syscalls.c — bare-metal _sbrk stub

Build: arm-none-eabi-gcc -Os -flto -Wall -Werror -Wextra
Size: 57.9KB Flash / 3.6KB RAM

Controls:
- 0-9: Direct frequency input (VFO)
- SK2: POCSAG mode
- SK1: Spectrum analyzer
- 0: FM Radio
- EXIT: Return to VFO
- F/*: Toggle 512/1200 baud (in POCSAG)

app/menu.h

@@ -0,0 +1,38 @@
+/* Copyright 2023 Dual Tachyon
+ * https://github.com/DualTachyon
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *     Unless required by applicable law or agreed to in writing, software
+ *     distributed under the License is distributed on an "AS IS" BASIS,
+ *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *     See the License for the specific language governing permissions and
+ *     limitations under the License.
+ */
+
+#ifndef APP_MENU_H
+#define APP_MENU_H
+
+#include "driver/keyboard.h"
+
+#ifdef ENABLE_F_CAL_MENU
+	void writeXtalFreqCal(const int32_t value, const bool update_eeprom);
+#endif
+
+extern uint8_t gUnlockAllTxConfCnt;
+
+int MENU_GetLimits(uint8_t menu_id, int32_t *pMin, int32_t *pMax);
+void MENU_AcceptSetting(void);
+void MENU_ShowCurrentSetting(void);
+void MENU_StartCssScan(void);
+void MENU_CssScanFound(void);
+void MENU_StopCssScan(void);
+
+void MENU_ProcessKeys(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld);
+
+#endif
+