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/Utilities/fetch_devtools.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+
+PACKCHK_VERSION=1.3.95
+SVDCONV_VERSION=3.3.42
+
+REPO_URL=https://github.com/Open-CMSIS-Pack/devtools
+DOWNLOAD_URL=${REPO_URL}/releases/download/
+DIRNAME=$(dirname $0)
+
+set -o pipefail
+
+function usage {
+  echo "$(basename $0) [-h|--help] [-f|--force]"
+  echo ""
+  echo "Arguments:"
+  echo "  -h|--help   Print this usage message and exit."
+  echo "  -f|--force  Force (re)download."
+  echo ""
+  echo "Environment:"
+  echo " curl"
+  echo " sha256sum"
+  echo ""
+}
+
+function fetch {
+  mkdir -p ${DIRNAME}/$2
+  pushd ${DIRNAME}/$2 >/dev/null
+  curl -O -L $1
+  unzip -o $(basename $1)
+  rm $(basename $1)
+  popd >/dev/null
+}
+
+POSITIONAL=()
+while [[ $# -gt 0 ]]
+do
+  key="$1"
+
+  case $key in
+    '-h'|'--help')
+      usage
+      exit 1
+    ;;
+    '-f'|'--force')
+      FORCE=1
+    ;;
+    *)    # unknown option
+      POSITIONAL+=("$1") # save it in an array for later
+    ;;
+  esac
+  shift # past argument
+done
+set -- "${POSITIONAL[@]}" # restore positional parameters
+
+fetch "${DOWNLOAD_URL}/tools%2Fpackchk%2F${PACKCHK_VERSION}/packchk-${PACKCHK_VERSION}-darwin64.zip" Darwin64
+fetch "${DOWNLOAD_URL}/tools%2Fpackchk%2F${PACKCHK_VERSION}/packchk-${PACKCHK_VERSION}-linux64.zip" Linux64
+fetch "${DOWNLOAD_URL}/tools%2Fpackchk%2F${PACKCHK_VERSION}/packchk-${PACKCHK_VERSION}-windows64.zip" Win32
+
+fetch "${DOWNLOAD_URL}/tools%2Fsvdconv%2F${SVDCONV_VERSION}/svdconv-${SVDCONV_VERSION}-darwin64.zip" Darwin64
+fetch "${DOWNLOAD_URL}/tools%2Fsvdconv%2F${SVDCONV_VERSION}/svdconv-${SVDCONV_VERSION}-linux64.zip" Linux64
+fetch "${DOWNLOAD_URL}/tools%2Fsvdconv%2F${SVDCONV_VERSION}/svdconv-${SVDCONV_VERSION}-windows64.zip" Win32
+
+exit 0