Implement BLE OTA

scripts/generate_dfu.py

@@ -0,0 +1,53 @@
+"""
+PlatformIO post-build script: generates a Nordic DFU package (.zip) from the
+built firmware .hex using adafruit-nrfutil.
+
+The resulting firmware_dfu.zip can be uploaded to the device via:
+  - nRF Connect mobile app (iOS / Android) after triggering OTA mode
+  - nRF Connect for Desktop
+  - adafruit-nrfutil over BLE (advanced)
+
+Trigger OTA mode on the device:
+  - Send BLE command 0x02 to cfgCommand (0x1236), OR
+  - Type 'o' in the serial monitor
+
+Usage: referenced from platformio.ini as:
+    extra_scripts = pre:scripts/git_hash.py, post:scripts/generate_dfu.py
+"""
+import subprocess, os
+
+Import("env")  # noqa: F821 - PlatformIO injects this
+
+def generate_dfu_package(source, target, env):
+    build_dir   = env.subst("$BUILD_DIR")
+    project_dir = env.subst("$PROJECT_DIR")
+    hex_path    = os.path.join(build_dir, "firmware.hex")
+
+    if not os.path.exists(hex_path):
+        print(f"[generate_dfu] firmware.hex not found at {hex_path}, skipping")
+        return
+
+    out_path = os.path.join(project_dir, "firmware_dfu.zip")
+
+    try:
+        result = subprocess.run(
+            [
+                "adafruit-nrfutil", "dfu", "genpkg",
+                "--dev-type", "0x0052",   # nRF52840
+                "--application", hex_path,
+                out_path,
+            ],
+            capture_output=True,
+            text=True,
+        )
+        if result.returncode == 0:
+            size_kb = os.path.getsize(out_path) / 1024
+            print(f"[generate_dfu] DFU package ready: firmware_dfu.zip ({size_kb:.1f} KB)")
+            print(f"[generate_dfu] Upload with nRF Connect after sending OTA command (0x02) via BLE")
+        else:
+            print(f"[generate_dfu] adafruit-nrfutil error: {result.stderr.strip()}")
+    except FileNotFoundError:
+        print("[generate_dfu] adafruit-nrfutil not found - skipping DFU package generation")
+        print("[generate_dfu] Install with: pip install adafruit-nrfutil")
+
+env.AddPostAction("$BUILD_DIR/firmware.hex", generate_dfu_package)  # noqa: F821