feat: GetMac command + MacAddress response

New protocol command (tag 8): GetMac returns the board's 6-byte hardware
address. Useful when multiple dongles are connected to one host.

Response (tag 6): MacAddress containing 6 raw bytes.

Updated: PROTOCOL.md, CHANGELOG, donglora.py decoder, all_commands.py.

CHANGELOG.md

@@ -10,7 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 ### Added
 
 - Transparent LoRa radio over USB CDC-ACM (VID `1209`, PID `5741`)
-- COBS-framed fixed-size LE binary protocol (8 commands, 6 responses)
+- COBS-framed fixed-size LE binary protocol (9 commands, 7 responses)
 - Radio configuration: frequency, bandwidth, spreading factor, coding rate, TX power
 - Continuous RX mode with RSSI/SNR per packet
 - Single-shot TX with optional per-packet config override

docs/PROTOCOL.md

@@ -59,6 +59,7 @@ Each command is a tag byte followed by fixed-size fields.
 | 5 | Transmit | has_config (1) + [RadioConfig if 1] + len (u16 LE) + payload |
 | 6 | DisplayOn | — |
 | 7 | DisplayOff | — |
+| 8 | GetMac | — |
 
 ## Responses (Firmware → Host)
 
@@ -70,6 +71,7 @@ Each command is a tag byte followed by fixed-size fields.
 | 3 | TxDone | — |
 | 4 | Ok | — |
 | 5 | Error | code (u8) |
+| 6 | MacAddress | 6 raw bytes (board's MAC/device address) |
 
 ## Bandwidth
 
@@ -128,9 +130,10 @@ Read back the response, COBS-decode it. First byte `0x04` = Ok.
 1. Open USB serial port (find by VID:PID `1209:5741`)
 2. Implement COBS encode/decode (libraries exist for every language)
 3. Pack commands with `struct.pack` or equivalent — all fields are fixed-size LE
-4. Send `SetConfig`, read back `Ok`
-5. Send `StartRx`, read back `Ok`
-6. Loop: read frames, decode `RxPacket` (rssi, snr, payload at known offsets)
-7. To transmit: send `Transmit`, read back `TxDone`
+4. Optionally send `GetMac`, read back `MacAddress` (useful with multiple dongles)
+5. Send `SetConfig`, read back `Ok`
+6. Send `StartRx`, read back `Ok`
+7. Loop: read frames, decode `RxPacket` (rssi, snr, payload at known offsets)
+8. To transmit: send `Transmit`, read back `TxDone`
 
 See `examples/` for working Python implementations.

examples/all_commands.py

@@ -42,7 +42,10 @@ try:
     print("\n── DisplayOn ──")
     print(dl.send(ser, "DisplayOn"))
 
-    print("\nAll 8 commands exercised successfully.")
+    print("\n── GetMac ──")
+    print(dl.send(ser, "GetMac"))
+
+    print("\nAll 9 commands exercised successfully.")
 
 except KeyboardInterrupt:
     print("\nInterrupted.")

examples/donglora.py

@@ -99,6 +99,7 @@ def encode_command(cmd: str, **kwargs) -> bytes:
     tags = {
         "Ping": 0, "GetConfig": 1, "SetConfig": 2, "StartRx": 3,
         "StopRx": 4, "Transmit": 5, "DisplayOn": 6, "DisplayOff": 7,
+        "GetMac": 8,
     }
     out = bytes([tags[cmd]])
     if cmd == "SetConfig":
@@ -144,6 +145,11 @@ def decode_response(data: bytes) -> dict:
     elif tag == 5:
         code = rest[0] if rest else -1
         return {"type": "Error", "code": code}
+    elif tag == 6:
+        if len(rest) >= 6:
+            mac = ":".join(f"{b:02X}" for b in rest[:6])
+            return {"type": "MacAddress", "mac": mac}
+        return {"type": "MacAddress", "raw": rest.hex()}
     else:
         return {"type": f"Unknown({tag})"}
 

src/protocol.rs

@@ -139,6 +139,7 @@ pub enum Command {
     },
     DisplayOn,
     DisplayOff,
+    GetMac,
 }
 
 impl Command {
@@ -178,6 +179,7 @@ impl Command {
             }
             6 => Some(Self::DisplayOn),
             7 => Some(Self::DisplayOff),
+            8 => Some(Self::GetMac),
             _ => None,
         }
     }
@@ -197,6 +199,7 @@ pub enum Response {
     TxDone,
     Ok,
     Error(ErrorCode),
+    MacAddress([u8; 6]),
 }
 
 impl Response {
@@ -232,6 +235,11 @@ impl Response {
                 buf[1] = code as u8;
                 2
             }
+            Self::MacAddress(mac) => {
+                buf[0] = 6;
+                buf[1..7].copy_from_slice(&mac);
+                7
+            }
         }
     }
 }

src/radio/task.rs

@@ -219,7 +219,7 @@ async fn handle_cmd(
             status.sender().send(state.clone());
             responses.send(Response::Ok).await;
         }
-        Command::DisplayOn | Command::DisplayOff => {}
+        Command::DisplayOn | Command::DisplayOff | Command::GetMac => {}
         Command::Transmit { config, payload } => {
             let tx_config = config.map(|c| c.resolve_power(Board::TX_POWER_RANGE)).or(state.config);
             if let Some(cfg) = tx_config {

src/usb/task.rs

@@ -207,6 +207,12 @@ async fn route_command(
                 responses.send(Response::Error(ErrorCode::NoDisplay)).await;
             }
         }
+        Command::GetMac => {
+            use crate::board::{Board, LoRaBoard};
+            responses
+                .send(Response::MacAddress(Board::mac_address()))
+                .await;
+        }
         other => {
             commands.send(other).await;
         }