USB HOST DRIVER V03 Freescale Semiconductor / Motorola, USB HOST DRIVER V03 Datasheet - Page 25

• Manufacturer Part Number: USB HOST DRIVER V03
• Description: USB Host Driver v03
• Manufacturer: Freescale Semiconductor / Motorola

3.4. Isochronous Transfers.
Isochronous transfers can be applied through the pipes opened on the Device. The Client
application should specify the special structure buffer to perform an isochronous transfer
operation using
of a fixed header and a variable length packets header and data parts. The isochronous
transfer buffer format is shown in the figure below:
Hence, the buffer that follows the header is divided into packets. Each packet is
transmitted within one USB frame (1 ms). The size of the packet can be different in each
frame. This allows support for any data rate of the isochronous data stream.
The isochronous transfer buffer is described by the
structure contains an array of
about packet data buffers. The
packet count in a given transfer.
M
ReadFile
Fig 3.1 Isochronous Transfer Buffer Format.
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
/
WriteFile
USB_ISO_XFER
USB_ISO_PACKET …
#2 Offset Length
#3 Offset Length
……………………………
#N Offset Length
Packet #1 Buffer
Packet #2 Buffer
Packet #3 Buffer
……………………………
Packet #N Buffer
StartFrame
Flags
ErrorCount
PacketCount
USB_ISO_PACKET
PacketCount
Programming Interface.
Win32 API functions. The buffer should consist
member of
structures, which provide information
Status
Status
Status
USB_ISO_XFER
USB_ISO_XFER
structure. This
determines the
3-3