Input And Output Structures - Motorola USB08 Reference Manual

NOTE:
E.5.4 Input and Output Structures
USB08 Evaluation Board
MOTOROLA
in the header. Because of that, the header contains a variable size array
of USBIO_ISO_PACKET
The Offset member of the USBIO_ISO_PACKET structure specifies the
byte offset of the corresponding packet relative to the beginning of the
whole buffer and has to be filled by the application for write and for read
transfers. The Length member defines the length, in bytes, of the packet.
The packet length has to be specified by the application for write
transfers and is returned by the USBIO on read transfers. The Status
member is used to return the completion status of the transfer of the
packet.
Isochronous Write Transfers
The sizes of the packets have to be less than or equal to the FIFO size
of the endpoint. There must not be gaps between the data packets in
the transfer buffer. The Offset and Length member of the
USBIO_ISO_PACKET structures have to be initialized correctly
before the transfer is started.
Isochronous Read Transfers
The size of each packet should be equal to the FIFO size. Otherwise
a data overrun error can occur. The Offset member of the
USBIO_ISO_PACKET structures has to be initialized correctly before
the transfer is started. There must not be gaps between the data
packets in the transfer buffer. The length of each received data packet
is returned in the Length member of the corresponding
USBIO_ISO_PACKET structure when the transfer completes.
Because the size of the received packets may be less than the FIFO size
the data packets are not arranged continuously within the transfer buffer.
This section provides a detailed description of the data structures that
are used with the various input and output requests.
Universal USB Device Driver (USBIO)
Universal USB Device Driver (USBIO)
(page 212) elements.
Programming Interface
Designer Reference Manual
185