Owners manual

Interfaces
H3 Datasheet(Revision1.2) Copyright© 2015 Allwinner Technology Co.,Ltd.All Rights Reserved. Page 493
8.5.2.5.6. EHCI USB Command Register (Default Value: 0x00080000,0x00080B00 if Asynchronous Schedule Park
Capability is a one)
Offset: 0x0010
Register Name: USBCMD
Bit
R/W
Default/Hex
Description
31:24
/
0
Reserved
These bits are reserved and should be set to zero.
23:16
R/W
0x08
Interrupt Threshold Control
The value in this field is used by system software to select the maximum
rate at which the host controller will issue interrupts. The only valid values
are defined below:
Value
Minimum Interrupt Interval
0x00
Reserved
0x01
1 micro-frame
0x02
2 micro-frame
0x04
4 micro-frame
0x08
8 micro-frame(default, equates to 1 ms)
0x10
16 micro-frame(2ms)
0x20
32 micro-frame(4ms)
0x40
64 micro-frame(8ms)
Any other value in this register yields undefined results.
The default value in this field is 0x08 .
Software modifications to this bit while HC Halted bit is equal to zero results
in undefined behavior.
15:12
/
0
Reserved
These bits are reserved and should be set to zero.
11
R/W or
R
0
Asynchronous Schedule Park Mode Enable(OPTIONAL)
If the Asynchronous Park Capability bit in the HCCPARAMS register is a one,
then this bit defaults to a 1 and is R/W. Otherwise the bit must be a zero and
is Read Only. Software uses this bit to enable or disable Park mode. When
this bit is one, Park mode is enabled. When this bit is zero, Park mode is
disabled.
10
/
0
Reserved
These bits are reserved and should be set to zero.
9:8
R/W or
R
0
Asynchronous Schedule Park Mode Count(OPTIONAL)
Asynchronous Park Capability bit in the HCCPARAMS register is a one,
Then this field defaults to 0x3 and is W/R. Otherwise it defaults to zero and
is R. It contains a count of the number of successive transactions the host
controller is allowed to execute from a high-speed queue head on the
Asynchronous schedule before continuing traversal of the Asynchronous
schedule.
Valid value are 0x1 to 0x3.Software must not write a zero to this bit when
Park Mode Enable is a one as it will result in undefined behavior.
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