From a921ebd4342310d6f0ba8b624f0521755c7bcf00 Mon Sep 17 00:00:00 2001
From: Jannik Beyerstedt <beyerstedt@consider-it.de>
Date: Tue, 18 Aug 2026 17:11:31 +0200
Subject: [PATCH] WIP BLE: Add "service change attribute"

TODO: doesn't work yet
See https://github.com/embassy-rs/trouble/issues/180 and maybe https://github.com/embassy-rs/trouble/issues/515
---
 Cargo.toml |  2 +-
 Readme.md  |  4 +---
 src/ble.rs | 28 +++++++++++++++++++++++-----
 3 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 0136b8e..01fa77b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -57,7 +57,7 @@ screen = ["dep:mipidsi", "dep:embedded-graphics", "dep:embedded-hal-bus", "dep:p
 # enable I/O via UART
 uart = ["_uart", "_gnss"]
 # enable I/O via BLE
-ble = ["_gnss", "denm"]
+ble = ["_gnss"]
 
 # internal feature, that any UART I/O is enabled
 _uart = []
diff --git a/Readme.md b/Readme.md
index 5fb34e6..16453c6 100644
--- a/Readme.md
+++ b/Readme.md
@@ -57,9 +57,7 @@ Enable UART I/O protocol according to [docs/uart-protocol.md](./docs/uart-protoc
 
 ### BLE
 Enable BLE I/O protocol according to [docs/ble-protocol.md](./docs/ble-protocol.md).
-Will enable `denm` feature, but also enabling `cam` is recommended for full functionality.
-
-Note: Raw message reception is currently not implemented!
+Enabling `denm` feature or `cam` feature is recommended, otherwise no data will be received.
 
 
 ## Usage
diff --git a/src/ble.rs b/src/ble.rs
index 64b175d..ff5f22d 100644
--- a/src/ble.rs
+++ b/src/ble.rs
@@ -41,9 +41,16 @@ pub enum BleSendable {
 
 #[gatt_server]
 struct Server {
+    generic: Generic,
     c_its_events: CITSEvents,
 }
 
+#[gatt_service(uuid = "1801")]
+pub(crate) struct Generic {
+    #[characteristic(uuid = characteristic::SERVICE_CHANGED, indicate, read, value = 0x0100FFFF)]
+    service_changed: u32,
+}
+
 #[gatt_service(uuid = "c0b70000-d4f4-4000-ada8-f99a02ee315c")]
 struct CITSEvents {
     #[descriptor(uuid = descriptors::MEASUREMENT_DESCRIPTION, name = "Position", read, value = "PositionState proto msg", type = &'static str)]
@@ -136,13 +143,20 @@ pub async fn run(
     );
     let server = Server::new_with_config(GapConfig::Peripheral(PeripheralConfig {
         name: "ESP32 C-ITS",
-        appearance: &appearance::UNKNOWN,
+        appearance: &appearance::UNKNOWN, // TODO MESH_DEVICE?? outdoor_sports_activity::LOCATION_AND_NAVIGATION_DISPLAY
     }))
     .unwrap();
 
+    let handle_start = 0x0100_u16; // little-endian
+    let handle_end = 0xFFFF_u16;
+    let concatenated: u32 = ((handle_start as u32) << 16) | handle_end as u32;
+    info!("Concatenated: {concatenated:?}");
+    let test = server.set(&server.generic.service_changed, &concatenated);
+    info!("We were able to set service changed? {test:?}");
+
     let _ = embassy_futures::join::join(ble_task(runner), async {
         loop {
-            match advertise("ESP32 C-ITS", &mut peripheral, &server).await {
+            match advertise(&mut peripheral, &server).await {
                 Ok(conn) => {
                     // set up tasks when the connection is established to a central, so they don't run when no one is connected.
                     let a = gatt_events_task(&server, &conn);
@@ -157,7 +171,7 @@ pub async fn run(
                     });
                 }
                 Err(e) => {
-                    panic!("BLE ADV: fatal error {e:?}");
+                    panic!("BLE ADV: fatal error: {e:?}");
                 }
             }
         }
@@ -182,15 +196,19 @@ pub fn update(payload: BleSendable) {
 
 /// Create an advertiser to use to connect to a BLE Central, and wait for it to connect.
 async fn advertise<'values, 'server, C: Controller>(
-    name: &'values str,
     peripheral: &mut Peripheral<'values, C, DefaultPacketPool>,
     server: &'server Server<'values>,
 ) -> Result<GattConnection<'values, 'server, DefaultPacketPool>, BleHostError<C::Error>> {
     let mut advertiser_data = [0; 35];
+    let service_uuid = Uuid::from(0xc0b70000d4f44000ada8f99a02ee315cu128)
+        .as_raw()
+        .try_into()
+        .unwrap();
     let len = AdStructure::encode_slice(
         &[
             AdStructure::Flags(LE_GENERAL_DISCOVERABLE | BR_EDR_NOT_SUPPORTED),
-            AdStructure::CompleteLocalName(name.as_bytes()),
+            AdStructure::ServiceUuids128(&[service_uuid]),
+            AdStructure::ServiceUuids16(&[service::GATT.to_le_bytes()]),
         ],
         &mut advertiser_data[..],
     )?;