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raspberrypi · Aug 23, 2024 · ec5a6d1 · ec5a6d1
1 parent e2977ac
commit ec5a6d1
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/src/rp2_common/pico_stdio_usb/stdio_usb_descriptors.c b/src/rp2_common/pico_stdio_usb/stdio_usb_descriptors.c
@@ -92,6 +92,10 @@
 static const tusb_desc_device_t usbd_desc_device = {
     .bLength = sizeof(tusb_desc_device_t),
     .bDescriptorType = TUSB_DESC_DEVICE,
+// On Windows, if bcdUSB = 0x210 then a Microsoft OS 2.0 descriptor is required, else the device won't be detected
+// This is only needed for driverless access to the reset interface - the CDC interface doesn't require these descriptors
+// for driverless access, but will still not work if bcdUSB = 0x210 and no descriptor is provided. Therefore always
+// use bcdUSB = 0x200 if the Microsoft OS 2.0 descriptor isn't enabled
 #if PICO_STDIO_USB_ENABLE_RESET_VIA_VENDOR_INTERFACE && PICO_STDIO_USB_RESET_INTERFACE_SUPPORT_MS_OS_20_DESCRIPTOR
     .bcdUSB = 0x0210,
 #else