Channel Usage Examples; With One Storage Device Connected - Epson S2R72V18 Technical Manual

1. Functions
1.4.1.4

Channel Usage Examples

1.4.1.4.1

With One Storage Device Connected

Fig. 1-21 shows a typical channel usage arrangement with a USB Mass Storage Class
(BulkOnly Transport Protocol) storage device (e.g., hard disk drive) connected. Devices
supporting this class use control, bulk IN, and bulk OUT transfers.
CH0 is used for control transfers.
While general channels are used for bulk IN and bulk OUT transfers, CHa in particular is
used when using the bulk-only support function with this LSI.
The bulk-only support function manages USB Mass Storage Class (BulkOnly Transport
Protocol) command transport (CBW), data transport, and status transport (CSW)
automatically (refer to "1.4.8 Bulk-Only Support Function"), and is included in CHa.
If the bulk-only support function is not used, bulk IN and bulk OUT transfers can be assigned
individually to general channels (such as CHb or CHc). In this case, transport must be
managed by software.
The hardware executes transactions by scheduling transfers to and from the channels (refer to
"1.4.2 Scheduling").
Fig. 1-21 Channel usage example (with one storage device connected)
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Host
F/W
IRP
HDD1
Ctl
HDD1 HDD1
BulkOut BulkIn
EPSON
Host Controller
(Channel Resister)
H/W
CH0
(for Ctl only)
CHa
(for Bulk 1)
CHb
(for Bulk/Int/Iso 1)
CHc
(for Bulk/Int/Iso 2)
CHd
(for Bulk/Int/Iso 3)
CHe
(for Bulk/Int/Iso 4)
S2R72V18 Technical Manual (Rev.1.00)
Device
Hdd1
Ctl
BulkIn
Bulkout