pybricksdev.usb: add Pybricks USB device class/subclass/protocol

This adds constants for the Pybricks USB device class, subclass and
protocol. These are used to identify hubs running the Pybricks firmware
when connected via USB.

The `usb` command of the CLI is modified to only accept Pybricks hubs
now. If we still want to support running programs on hubs running
official LEGO firmware, we can add that back with a different command
name.

Co-authored-by: Nate Karstens <nate.karstens@gmail.com>

pybricksdev/cli/__init__.py

@@ -20,6 +20,12 @@
 
 from .. import __name__ as MODULE_NAME
 from .. import __version__ as MODULE_VERSION
+from ..usb import (
+    LEGO_USB_VID,
+    PYBRICKS_USB_DEVICE_CLASS,
+    PYBRICKS_USB_DEVICE_PROTOCOL,
+    PYBRICKS_USB_DEVICE_SUBCLASS,
+)
 
 PROG_NAME = (
     f"{path.basename(sys.executable)} -m {MODULE_NAME}"
@@ -171,9 +177,10 @@ def add_parser(self, subparsers: argparse._SubParsersAction):
             )
 
     async def run(self, args: argparse.Namespace):
+        from usb.core import find as find_usb
+
         from ..ble import find_device as find_ble
         from ..connections.ev3dev import EV3Connection
-        from ..connections.lego import REPLHub
         from ..connections.pybricks import PybricksHub
 
         # Pick the right connection
@@ -192,8 +199,17 @@ async def run(self, args: argparse.Namespace):
             device_or_address = await find_ble(args.name)
 
         elif args.conntype == "usb":
-            hub = REPLHub()
-            device_or_address = None
+            hub = PybricksHub()
+            device_or_address = find_usb(
+                idVendor=LEGO_USB_VID,
+                bDeviceClass=PYBRICKS_USB_DEVICE_CLASS,
+                bDeviceSubClass=PYBRICKS_USB_DEVICE_SUBCLASS,
+                bDeviceProtocol=PYBRICKS_USB_DEVICE_PROTOCOL,
+            )
+            if device_or_address is None:
+                print("No Pybricks USB device found.", file=sys.stderr)
+                exit(1)
+
         else:
             raise ValueError(f"Unknown connection type: {args.conntype}")
 

pybricksdev/usb/__init__.py

@@ -21,3 +21,8 @@ class LegoUsbPid(_enum.IntEnum):
     SPIKE_ESSENTIAL = 0x000D
     ROBOT_INVENTOR = 0x0010
     ROBOT_INVENTOR_DFU = 0x0011
+
+
+PYBRICKS_USB_DEVICE_CLASS = 0xFF
+PYBRICKS_USB_DEVICE_SUBCLASS = 0xC5
+PYBRICKS_USB_DEVICE_PROTOCOL = 0xF5