
Functional Description and Application Information
MC9328MXL Technical Data, Rev. 8
72
Freescale Semiconductor
Figure 55. SDRAM Self-Refresh Cycle Timing Diagram
4.11
USB Device Port
Four types of data transfer modes exist for the USB module: control transfers, bulk transfers, isochronous
transfers, and interrupt transfers. From the perspective of the USB module, the interrupt transfer type is
identical to the bulk data transfer mode, and no additional hardware is supplied to support it. This section
covers the transfer modes and how they work from the ground up.
Data moves across the USB in packets. Groups of packets are combined to form data transfers. The same
packet transfer mechanism applies to bulk, interrupt, and control transfers. Isochronous data is also moved
in the form of packets, however, because isochronous pipes are given a fixed portion of the USB
bandwidth at all times, there is no end-of-transfer.
SDCLK
CS
CAS
RAS
ADDR
DQ
DQM
BA
WE
CKE