Bluetooth (#518)

* Bluetooth LE addition

* fixes

* use the psram!

helps a little on S3 (t-deck)

* custom device name

* Update symbols.c

* Feedback + fixes

Fixes external app start/stop server (child devices)
Fixes BtManage causing a full system hang upon disabling bt when a device is connected to the host.

* updoot

* more updoot

* move back!

* Revert "move back!"

This reverts commit d3694365c634acc5db62ac59771c496cb971a727.

* fix some of the things

* Addressing feedback? hmm

* Fixes

Bug 1 — Reconnect loop / Reconnect not working fixed
Bug 2 — Name-only advertising overwrites HID advertising
Bug 3 — BleHidDeviceCtx leak on re-enable
Enhancement — HID device auto-start on radio re-enable

* stuff...

* update for consistency with others

* fix crashes

and some bonus symbols

* a few symbols, i2c speed, cdn message

100kHz i2c speed seems to be more compatible with m5stack modules...and probably in general.
cdn message no longer applies

* Hide BT Settings when bt not enabled

* Addressing things and device fixes

* Missed one!

* stuff

device.py

@@ -307,6 +307,39 @@ def write_usb_variables(output_file, device_properties: ConfigParser):
         output_file.write("CONFIG_TINYUSB_MSC_ENABLED=y\n")
         output_file.write("CONFIG_TINYUSB_MSC_MOUNT_PATH=\"/sdcard\"\n")
 
+def write_bluetooth_variables(output_file, device_properties: ConfigParser):
+    idf_target = get_property_or_exit(device_properties, "hardware", "target").lower()
+    has_bluetooth = get_boolean_property_or_false(device_properties, "hardware", "bluetooth")
+    if has_bluetooth:
+        output_file.write("# Bluetooth (NimBLE)\n")
+        output_file.write("CONFIG_BT_ENABLED=y\n")
+        output_file.write("CONFIG_BT_NIMBLE_ENABLED=y\n")
+        if idf_target == "esp32p4":
+            output_file.write("CONFIG_BT_NIMBLE_TRANSPORT_UART=n\n")
+            output_file.write("CONFIG_ESP_HOSTED_ENABLE_BT_NIMBLE=y\n")
+        # Move NimBLE host buffers to SPIRAM when available, regardless of target.
+        # The default (INTERNAL) mode causes heap fragmentation after a disable+deinit
+        # cycle, preventing a subsequent nimble_port_init() from allocating its buffers
+        # ("hci inits failed" / rc=-1). EXTERNAL mode uses SPIRAM, which is much larger
+        # and does not suffer from the same fragmentation — enabling reliable re-init.
+        # Also frees significant internal RAM on memory-constrained targets (e.g. S3).
+        # Dependency: CONFIG_SPIRAM_USE_CAPS_ALLOC || CONFIG_SPIRAM_USE_MALLOC (set by write_spiram_variables).
+        has_spiram = get_boolean_property_or_false(device_properties, "hardware", "spiRam")
+        if has_spiram:
+            output_file.write("CONFIG_BT_NIMBLE_MEM_ALLOC_MODE_EXTERNAL=y\n")
+        # Expand NimBLE's GAP device name buffer to match BLE_DEVICE_NAME_MAX.
+        # The default (31) is too short for some device names and leaves no headroom.
+        output_file.write("CONFIG_BT_NIMBLE_GAP_DEVICE_NAME_MAX_LEN=64\n")
+        # Increase NimBLE host task stack from the 4096-byte default.
+        # GAP/GATT event processing + C++ frames push the default over the limit,
+        # causing stack-protection faults on events like BLE_GAP_EVENT_SUBSCRIBE.
+        output_file.write("CONFIG_BT_NIMBLE_HOST_TASK_STACK_SIZE=8192\n")
+        # Persist bond/CCCD data to NVS so that bonds survive BLE disable+re-enable
+        # cycles (nimble_port_deinit clears RAM-only state). Without this, bonded peers
+        # (e.g. Windows HID host) lose their LTK match on re-enable and enter a
+        # rapid connect/disconnect/re-pair loop.
+        output_file.write("CONFIG_BT_NIMBLE_NVS_PERSIST=y\n")
+
 def write_custom_sdkconfig(output_file, device_properties: ConfigParser):
     if "sdkconfig" in device_properties.sections():
         output_file.write("# Custom\n")
@@ -325,6 +358,7 @@ def write_properties(output_file, device_properties: ConfigParser, device_id: st
     write_spiram_variables(output_file, device_properties)
     write_performance_improvements(output_file, device_properties)
     write_usb_variables(output_file, device_properties)
+    write_bluetooth_variables(output_file, device_properties)
     write_custom_sdkconfig(output_file, device_properties)
     write_lvgl_variables(output_file, device_properties)