WIP: get Heltec V3 working

clients/rust/src/discovery.rs

@@ -13,18 +13,41 @@ pub const USB_VID: u16 = 0x1209;
 /// DongLoRa USB Product ID.
 pub const USB_PID: u16 = 0x5741;
 
+/// Known USB-UART bridge VID:PIDs found on some board revisions.
+const BRIDGE_VID_PIDS: &[(u16, u16)] = &[
+    (0x10C4, 0xEA60), // CP2102 (Silicon Labs)
+    (0x1A86, 0x55D4), // CH9102
+    (0x1A86, 0x7523), // CH340
+    (0x0403, 0x6001), // FT232R (FTDI)
+];
+
 /// Find the DongLoRa serial port by USB VID:PID.
 ///
+/// Checks for native USB CDC-ACM first (VID:PID 1209:5741), then falls
+/// back to known USB-UART bridge chips found on some board revisions.
 /// Returns the first matching port path, or `None` if no device is found.
 pub fn find_port() -> Option<String> {
     let ports = serialport::available_ports().ok()?;
+
+    // Prefer native USB (our custom VID:PID)
+    if let Some(port) = ports.iter().find(|p| {
+        matches!(
+            &p.port_type,
+            serialport::SerialPortType::UsbPort(info)
+                if info.vid == USB_VID && info.pid == USB_PID
+        )
+    }) {
+        return Some(port.port_name.clone());
+    }
+
+    // Fall back to known USB-UART bridge chips
     ports
         .into_iter()
         .find(|p| {
             matches!(
                 &p.port_type,
                 serialport::SerialPortType::UsbPort(info)
-                    if info.vid == USB_VID && info.pid == USB_PID
+                    if BRIDGE_VID_PIDS.contains(&(info.vid, info.pid))
             )
         })
         .map(|p| p.port_name)