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)

ui/aircopy.c

@@ -0,0 +1,72 @@
+/* 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.
+ */
+
+#ifdef ENABLE_AIRCOPY
+
+#include <string.h>
+
+#include "app/aircopy.h"
+#include "driver/st7565.h"
+#include "external/printf/printf.h"
+#include "misc.h"
+#include "radio.h"
+#include "ui/aircopy.h"
+#include "ui/helper.h"
+#include "ui/inputbox.h"
+
+void UI_DisplayAircopy(void)
+{
+	char String[16] = { 0 };
+	char *pPrintStr = { 0 };
+
+	UI_DisplayClear();
+
+	if (gAircopyState == AIRCOPY_READY) {
+		pPrintStr = "AIR COPY(RDY)";
+	} else if (gAircopyState == AIRCOPY_TRANSFER) {
+		pPrintStr = "AIR COPY";
+	} else {
+		pPrintStr = "AIR COPY(CMP)";
+	}
+
+	UI_PrintString(pPrintStr, 2, 127, 0, 8);
+
+	if (gInputBoxIndex == 0) {
+		uint32_t frequency = gRxVfo->freq_config_RX.Frequency;
+		sprintf(String, "%3u.%05u", frequency / 100000, frequency % 100000);
+		// show the remaining 2 small frequency digits
+		UI_PrintStringSmallNormal(String + 7, 97, 0, 3);
+		String[7] = 0;
+		// show the main large frequency digits
+		UI_DisplayFrequency(String, 16, 2, false);
+	} else {
+		const char *ascii = INPUTBOX_GetAscii();
+		sprintf(String, "%.3s.%.3s", ascii, ascii + 3);
+		UI_DisplayFrequency(String, 16, 2, false);
+	}
+
+	memset(String, 0, sizeof(String));
+	if (gAirCopyIsSendMode == 0) {
+		sprintf(String, "RCV:%u E:%u", gAirCopyBlockNumber, gErrorsDuringAirCopy);
+	} else if (gAirCopyIsSendMode == 1) {
+		sprintf(String, "SND:%u", gAirCopyBlockNumber);
+	}
+	UI_PrintString(String, 2, 127, 4, 8);
+
+	ST7565_BlitFullScreen();
+}
+
+#endif