I could be wrong, but I believe that when the teensy is setup to emulate a keyboard it is setup to be boot protocol...
That is:
Code:
#ifdef KEYBOARD_INTERFACE
// interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
9, // bLength
4, // bDescriptorType
KEYBOARD_INTERFACE, // bInterfaceNumber
0, // bAlternateSetting
1, // bNumEndpoints
0x03, // bInterfaceClass (0x03 = HID)
0x01, // bInterfaceSubClass (0x01 = Boot)
0x01, // bInterfaceProtocol (0x01 = Keyboard)
0, // iInterface
// HID interface descriptor, HID 1.11 spec, section 6.2.1
9, // bLength
0x21, // bDescriptorType
0x11, 0x01, // bcdHID
0, // bCountryCode
1, // bNumDescriptors
0x22, // bDescriptorType
LSB(sizeof(keyboard_report_desc)), // wDescriptorLength
MSB(sizeof(keyboard_report_desc)),
// endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
7, // bLength
5, // bDescriptorType
KEYBOARD_ENDPOINT | 0x80, // bEndpointAddress
0x03, // bmAttributes (0x03=intr)
KEYBOARD_SIZE, 0, // wMaxPacketSize
KEYBOARD_INTERVAL, // bInterval
#endif // KEYBOARD_INTERFACE
Maybe long shot, but maybe issue on where you plug the teensy in? On one of my older machines with a USB 3 board in it, if I plug in a keyboard into a USB3 slot, it does not work during boot process, but if I plug it into USB2 slot, it works fine... Again probably a long shot, but thought I would mention.