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)

external/CMSIS_5/CMSIS/RTOS2/RTX/Template/main.c

@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------
+ * CMSIS-RTOS 'main' function template
+ *---------------------------------------------------------------------------*/
+ 
+#include "RTE_Components.h"
+#include  CMSIS_device_header
+#include "cmsis_os2.h"
+ 
+/*----------------------------------------------------------------------------
+ * Application main thread
+ *---------------------------------------------------------------------------*/
+__NO_RETURN static void app_main (void *argument) {
+  (void)argument;
+  // ...
+  for (;;) {}
+}
+ 
+int main (void) {
+ 
+  // System Initialization
+  SystemCoreClockUpdate();
+  // ...
+ 
+  osKernelInitialize();                 // Initialize CMSIS-RTOS
+  osThreadNew(app_main, NULL, NULL);    // Create application main thread
+  osKernelStart();                      // Start thread execution
+  for (;;) {}
+}