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)

debugging.h

@@ -0,0 +1,48 @@
+#ifndef DEBUGGING_H
+#define DEBUGGING_H
+
+#ifdef ENABLE_UART
+
+#include "driver/uart.h"
+#include "driver/bk4819.h"
+#include "string.h"
+#include "external/printf/printf.h"
+#include "am_fix.h"
+
+static inline void LogUart(const char *const str)
+{
+	UART_Send(str, strlen(str));
+}
+
+static inline void LogUartf(const char* format, ...)
+{
+	char buffer[128];
+	va_list va;
+	va_start(va, format);
+	vsnprintf(buffer, (size_t)-1, format, va);
+	va_end(va);
+	UART_Send(buffer, strlen(buffer));
+}
+
+static inline void LogRegUart(uint16_t reg)
+{
+	uint16_t regVal = BK4819_ReadRegister(reg);
+	char buf[32];
+	sprintf(buf, "reg%02X: %04X\n", reg, regVal);
+	LogUart(buf);
+}
+
+static inline void LogPrint()
+{
+	uint16_t rssi = BK4819_GetRSSI();
+	uint16_t reg7e = BK4819_ReadRegister(0x7E);
+	char buf[32];
+	sprintf(buf, "reg7E: %d  %2d  %6d  %2d  %d   rssi: %d\n", (reg7e >> 15),
+		(reg7e >> 12) & 0b111, (reg7e >> 5) & 0b1111111,
+		(reg7e >> 2) & 0b111, (reg7e >> 0) & 0b11, rssi);
+	LogUart(buf);
+}
+
+#endif
+
+#endif