A20 User Manual (Revision 1.2) Copyright © 2013 Allwinner Technology Co., Ltd. All Rights Reserved. Page 687 / 812
in the PCED, through bit 0 to bit 3 must be zero in this field.
6.8.7.12. HCBULKCURRENTED REGISTER
Register Name: HcBulkCurrentED [BCED]
Default Value: 0x0
BulkCurrentED[31:4]
This is advanced to the next ED after the HC has served the
present one. HC continues processing the list from where it left off
in the last Frame. When it reaches the end of the Bulk list, HC
checks the ControlListFilled of HcControl. If set, it copies the
content of HcBulkHeadED to HcBulkCurrentED and clears the bit.
If it is not set, it does nothing. HCD is only allowed to modify this
register when the BulkListEnable of HcControl is cleared. When
set, the HCD only reads the instantaneous value of this register.
This is initially set to zero to indicate the end of the Bulk list.
BulkCurrentED [3:0]
Because the general TD length is 16 bytes, the memory structure
for the TD must be aligned to a 16-byte boundary. So the lower bits
in the PCED, through bit 0 to bit 3 must be zero in this field.
6.8.7.13. HCDONEHEAD REGISTER
Register Name: HcDoneHead
Default Value:0x0
HcDoneHead[31:4]
When a TD is completed, HC writes the content of HcDoneHead to
the NextTD field of the TD. HC then overwrites the content of
HcDoneHead with the address of this TD. This is set to zero
whenever HC writes the content of this register to HCCA. It also
sets the WritebackDoneHead of HcInterruptStatus.
HcDoneHead[3:0]
Because the general TD length is 16 bytes, the memory structure
for the TD must be aligned to a 16-byte boundary. So the lower bits
in the PCED, through bit 0 to bit 3 must be zero in this field.
6.8.7.14. HCFMINTERVAL REGISTER
Register Name: HcFmInterval Register
Default Value:0x2edf
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