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/DoxyGen/Driver/src/SPI_Demo.c

@@ -0,0 +1,98 @@
+#include "Driver_SPI.h"
+#include "cmsis_os.h"                   // ARM::CMSIS:RTOS:Keil RTX
+ 
+ 
+void mySPI_Thread(void const *argument);
+osThreadId tid_mySPI_Thread;
+ 
+ 
+/* SPI Driver */
+extern ARM_DRIVER_SPI Driver_SPI0;
+ 
+ 
+void mySPI_callback(uint32_t event)
+{
+    switch (event)
+    {
+    case ARM_SPI_EVENT_TRANSFER_COMPLETE:
+        /* Success: Wakeup Thread */
+        osSignalSet(tid_mySPI_Thread, 0x01);
+        break;
+    case ARM_SPI_EVENT_DATA_LOST:
+        /*  Occurs in slave mode when data is requested/sent by master
+            but send/receive/transfer operation has not been started
+            and indicates that data is lost. Occurs also in master mode
+            when driver cannot transfer data fast enough. */
+        __breakpoint(0);  /* Error: Call debugger or replace with custom error handling */
+        break;
+    case ARM_SPI_EVENT_MODE_FAULT:
+        /*  Occurs in master mode when Slave Select is deactivated and
+            indicates Master Mode Fault. */
+        __breakpoint(0);  /* Error: Call debugger or replace with custom error handling */
+        break;
+    }
+}
+ 
+/* Test data buffers */
+const uint8_t testdata_out[8] = { 0, 1, 2, 3, 4, 5, 6, 7 }; 
+uint8_t       testdata_in [8];
+ 
+void mySPI_Thread(void const* arg)
+{
+    ARM_DRIVER_SPI* SPIdrv = &Driver_SPI0;
+    osEvent evt;
+ 
+#ifdef DEBUG
+    ARM_DRIVER_VERSION   version;
+    ARM_SPI_CAPABILITIES drv_capabilities;
+ 
+    version = SPIdrv->GetVersion();
+    if (version.api < 0x200) /* requires at minimum API version 2.00 or higher */
+    {                        /* error handling                                 */
+        return;
+    }
+ 
+    drv_capabilities = SPIdrv->GetCapabilities();
+    if (drv_capabilities.event_mode_fault == 0)
+    {                        /* error handling */
+        return;
+    }
+#endif
+ 
+    /* Initialize the SPI driver */
+    SPIdrv->Initialize(mySPI_callback);
+    /* Power up the SPI peripheral */
+    SPIdrv->PowerControl(ARM_POWER_FULL);
+    /* Configure the SPI to Master, 8-bit mode @10000 kBits/sec */
+    SPIdrv->Control(ARM_SPI_MODE_MASTER | ARM_SPI_CPOL1_CPHA1 | ARM_SPI_MSB_LSB | ARM_SPI_SS_MASTER_SW | ARM_SPI_DATA_BITS(8), 10000000);
+ 
+    /* SS line = INACTIVE = HIGH */
+    SPIdrv->Control(ARM_SPI_CONTROL_SS, ARM_SPI_SS_INACTIVE);
+ 
+    /* thread loop */
+    while (1)
+    {
+        /* SS line = ACTIVE = LOW */
+        SPIdrv->Control(ARM_SPI_CONTROL_SS, ARM_SPI_SS_ACTIVE);
+        /* Transmit some data */
+        SPIdrv->Send(testdata_out, sizeof(testdata_out));
+        /* Wait for completion */
+        evt = osSignalWait(0x01, 100);
+        if (evt.status == osEventTimeout) {
+            __breakpoint(0); /* Timeout error: Call debugger */
+        }
+        /* SS line = INACTIVE = HIGH */
+        SPIdrv->Control(ARM_SPI_CONTROL_SS, ARM_SPI_SS_INACTIVE);
+
+        /* SS line = ACTIVE = LOW */
+        SPIdrv->Control(ARM_SPI_CONTROL_SS, ARM_SPI_SS_ACTIVE);
+        /* Receive 8 bytes of reply */
+        SPIdrv->Receive(testdata_in, 8);
+        evt = osSignalWait(0x01, 100);
+        if (evt.status == osEventTimeout) {
+            __breakpoint(0); /* Timeout error: Call debugger */
+        }
+        /* SS line = INACTIVE = HIGH */
+        SPIdrv->Control(ARM_SPI_CONTROL_SS, ARM_SPI_SS_INACTIVE);
+    }
+}