HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 833

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

24.3.3
The host controller uses USBHCS not only for reflecting the current status of the host controller,
but also for receiving a command issued by HCD. A write is for setting HCD. The host controller
must guarantee that the bit to which 1 is written to be set and the bit to which 0 is written to is
unchanged. HCD must distribute multiple clear commands to the host controller by a previously
issued command. The host controller driver can read all bits normally.
The SOC bit indicates the number of the frame that has detected the Scheduling Overrun error by
the host controller. This occurs when the periodic list has not completed before EOF. When the
Scheduling Overrun error is detected, the host controller increments the counter and sets SO bit in
the USBHIS register.
Bit
2
1
0
Hc Command Status Register (USBHCS)
Bit Name
PLE
CBSR1
CBSR0
Initial
Value
0
0
0
R/W
R/W
R/W
R/W
Description
Periodic List Enable
This bit is set to enable the processing of the periodic list.
If cleared by HCD, no periodic list processing is carried out
after next SOF. HC must check this bit before HC starts to
process the list.
0: The periodic list processing is not carried out after next
1: The periodic list processing is carried out after next
Control Bulk Service Ratio
This bit specifies the service ration of the control and bulk
ED. The host controller must compare the ratio specified
by the internal calculation whether it has processed
several non-vacant control ED in determining whether
another control ED is continued to be supplied or switched
to bulk ED before any a periodic list is processed. In case
of reset, HCD is responsible for restoring this value.
00: 1:1
01: 2:1
10: 3:1
11: 4:1
SOF
SOF
Rev. 3.00 Jan. 18, 2008 Page 771 of 1458
Section 24
USB Host Controller (USBH)
REJ09B0033-0300