On Windows, create the libusb1 backend explicitly by specifying the i…

…nstalled location of libusb-1.0.dll

apollo_fpga/__init__.py

@@ -92,7 +92,7 @@ def __init__(self, force_offline=False):
         device = self._find_device(self.APOLLO_USB_IDS, custom_match=self._device_has_apollo_id)
 
         # If Apollo VID/PID is not found, try to find a gateware VID/PID with a valid Apollo stub
-        # interface. If found, request the gateware to liberate the USB port. In devices with a 
+        # interface. If found, request the gateware to liberate the USB port. In devices with a
         # shared port, this effectively hands off the USB port to Apollo.
         if device is None:
 
@@ -111,7 +111,7 @@ def __init__(self, force_offline=False):
                 raise DebuggerNotFound(f"Handoff request failed: {e.strerror}")
 
             # Wait for Apollo to enumerate and try again
-            time.sleep(2) 
+            time.sleep(2)
             device = self._find_device(self.APOLLO_USB_IDS, custom_match=self._device_has_apollo_id)
             if device is None:
                 raise DebuggerNotFound("Handoff was requested, but Apollo is not available")
@@ -150,10 +150,29 @@ def _request_handoff(cls, device):
 
     @staticmethod
     def _find_device(ids, custom_match=None):
+        import usb.backend.libusb1
+
+        # In Windows, we need to specify the libusb library location to create a backend.
+        if platform.system() == "Windows":
+            # Determine the path to libusb-1.0.dll.
+            try:
+                from importlib_resources import files # <= 3.8
+            except:
+                from importlib.resources import files # >= 3.9
+            libusb_dll = os.path.join(files("usb1"), "libusb-1.0.dll")
+
+            # Create a backend by explicitly passing the path to libusb_dll.
+            backend = usb.backend.libusb1.get_backend(find_library=lambda x: libusb_dll)
+        else:
+            # On other systems we can just use the default backend.
+            backend = usb.backend.libusb1.get_backend()
+
+        # Find the device.
         for vid, pid in ids:
-            device = usb.core.find(idVendor=vid, idProduct=pid, custom_match=custom_match)
+            device = usb.core.find(backend=backend, idVendor=vid, idProduct=pid, custom_match=custom_match)
             if device is not None:
                 return device
+
         return None
 
     @staticmethod
@@ -282,7 +301,7 @@ def create_jtag_programmer(self, jtag_chain):
     def create_jtag_spi(self, jtag_chain):
         """ Returns a JTAG-over-SPI connection for the given device. """
 
-        # If this is an external programmer, we don't yet know how to create a JTAG-SPI 
+        # If this is an external programmer, we don't yet know how to create a JTAG-SPI
         # interface for it. For now, assume we can't.
         if self.major == self.EXTERNAL_BOARD_MAJOR:
             return None, None

apollo_fpga/gateware/flash_bridge.py

@@ -34,7 +34,7 @@
 class SPIStreamController(Elaboratable):
     """ Class that drives a SPI bus with data from input stream packets.
     Data received from the device is returned as another packet."""
-    
+
     def __init__(self):
         self.period = 4  # powers of two only
         self.bus    = SPIBus()
@@ -56,7 +56,7 @@ def elaborate(self, platform):
             sck_fall.eq( sck_d & ~self.bus.sck),  # falling edge
             sck_rise.eq(~sck_d &  self.bus.sck),  # rising edge
         ]
-        
+
         # I/O shift registers, bit counter and last flag
         shreg_o = Signal(8)
         shreg_i = Signal(8)
@@ -114,7 +114,7 @@ def elaborate(self, platform):
                             m.next = 'END'
                         with m.Elif(~self.input.valid):
                             m.next = 'WAIT'
-            
+
             with m.State("END"):
                 m.d.comb += [
                     self.input.ready    .eq(0),
@@ -134,7 +134,7 @@ def elaborate(self, platform):
             ]
 
         return m
-    
+
 
 class FlashBridgeRequestHandler(USBRequestHandler):
     """ Request handler that can trigger a FPGA reconfiguration. """
@@ -168,7 +168,7 @@ def elaborate(self, platform):
 
                     # Once the receive is complete, respond with an ACK.
                     with m.If(interface.rx_ready_for_response):
-                        m.d.comb += interface.handshakes_out.ack.eq(1)    
+                        m.d.comb += interface.handshakes_out.ack.eq(1)
 
                     # If we reach the status stage, send a ZLP.
                     with m.If(interface.status_requested):
@@ -181,7 +181,7 @@ def elaborate(self, platform):
 class FlashBridgeSubmodule(Elaboratable):
     """ Implements gateware for the USB<->SPI bridge. Intended to use as a submodule
         See example in FlashBridge """
-    
+
     def __init__(self, endpoint):
         # Endpoint number for the in/out stream endpoints
         self.endpoint = endpoint
@@ -354,12 +354,15 @@ class FlashBridgeNotFound(IOError):
 class FlashBridgeConnection:
     def __init__(self):
         # Try to create a connection to our configuration flash bridge.
-        device = usb.core.find(idVendor=VENDOR_ID, idProduct=PRODUCT_ID, custom_match=self._find_cfg_flash_bridge)
+        device = ApolloDebugger._find_device(
+            ids=[(VENDOR_ID, PRODUCT_ID)],
+            custom_match=self._find_cfg_flash_bridge
+        )
 
         # If we couldn't find the bridge, bail out.
         if device is None:
             raise FlashBridgeNotFound("Unable to find device")
-        
+
         self.device = device
         self.interface, self.endpoint = self._find_cfg_flash_bridge(device, get_ep=True)