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/Semaphore.c

@@ -0,0 +1,50 @@
+#include "cmsis_os2.h"                          // CMSIS RTOS header file
+ 
+/*----------------------------------------------------------------------------
+ *      Semaphore creation & usage
+ *---------------------------------------------------------------------------*/
+ 
+osSemaphoreId_t sid_Semaphore;                  // semaphore id
+ 
+osThreadId_t tid_Thread_Semaphore;              // thread id
+ 
+void Thread_Semaphore (void *argument);         // thread function
+ 
+int Init_Semaphore (void) {
+ 
+  sid_Semaphore = osSemaphoreNew(2U, 2U, NULL);
+  if (sid_Semaphore == NULL) {
+    ; // Semaphore object not created, handle failure
+  }
+ 
+  tid_Thread_Semaphore = osThreadNew(Thread_Semaphore, NULL, NULL);
+  if (tid_Thread_Semaphore == NULL) {
+    return(-1);
+  }
+ 
+  return(0);
+}
+ 
+void Thread_Semaphore (void *argument) {
+  int32_t val;
+ 
+  while (1) {
+    ; // Insert thread code here...
+ 
+    val = osSemaphoreAcquire(sid_Semaphore, 10U);       // wait 10 mSec
+    switch (val) {
+      case osOK:
+        ; // Use protected code here...
+        osSemaphoreRelease(sid_Semaphore);              // return a token back to a semaphore
+        break;
+      case osErrorResource:
+        break;
+      case osErrorParameter:
+        break;
+      default:
+        break;
+    }
+ 
+    osThreadYield();                                    // suspend thread
+  }
+}