In document : USB Simply Buffered (USB) Mass Storage Class – Bulk-Only Transport Copyright © 2007. Shakthi Kannan. In section 1.1.1 Setup Packet, we see: PID !PID Func Add Ep CRC L M L M L M L M L M 1011 0100 1100 000 0000 01010 More precisely: Func Add =1100 000 (L->M) Endpoint = 0000 (L->M) CRC5 = 01010 Is this a good CRC5 ? Best wishes. Sedki -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html