Allwinner A20 - Page 688

A20 User Manual (Revision 1.2) Copyright © 2013 Allwinner Technology Co., Ltd. All Rights Reserved. Page 688 / 812
31
R/W
R
0x0
FrameIntervalToggler
HCD toggles this bit whenever it loads a new value to
FrameInterval.
30:16
R/W
R
0x0
FSLargestDataPacket
This field specifies a value which is loaded into the Largest Data
Packet Counter at the beginning of each frame. The counter value
represents the largest amount of data in bits which can be sent or
received by the HC in a single transaction at any given time without
causing scheduling overrun. The field value is calculated by the
HCD.
15:14
Reserved
13:0
R/W
R
0x2edf
FrameInterval
This specifies the interval between two consecutive SOFs in bit
times. The nominal value is set to be 11,999. HCD should store the
current value of this field before resetting HC. By setting the
HostControllerReset field of HcCommandStatus as this will
cause the HC to reset this field to its nominal value. HCD may
choose to restore the stored value upon the completion of the
Reset sequence.
6.8.7.15. HCFMREMAINING REGISTER
Offset: 0x438
Register Name: HcFmRemaining
Default Value: 0x0
Bit
Read/Write
Default
Description
HCD
HC
31
R
R/W
0x0
FrameRemaining Toggle
This bit is loaded from the FrameIntervalToggle field of
HcFmInterval whenever FrameRemaining reaches 0. This bit is
used by HCD for the synchronization between FrameInterval and
FrameRemaining.
30:14
/
/
/
Reserved
13:0
R
RW
0x0
FramRemaining
This counter is decremented at each bit time. When it reaches
zero, it is reset by loading the FrameInterval value specified in
HcFmInterval at the next bit time boundary. When entering the
USBOPERATIONAL state, HC re-loads the content with the
FrameInterval of HcFmInterval and uses the updated value from
the next SOF.
6.8.7.16. HCFMNUMBER REGISTER
Offset: 0x43c
Register Name: HcFmNumber
Default Value:0x0
Bit
Read/Write
Default
Description
HCD
HC
31:16
/
/
/
Reserved