A20 User Manual (Revision 1.2) Copyright © 2013 Allwinner Technology Co., Ltd. All Rights Reserved. Page 686 / 812
CHED[31:4]
The HcControlHeadED register contains the physical address of
the first
Endpoint Descriptor of the Control list. HC traverse the Control list
starting with the HcControlHeadED pointer. The content is loaded
from HCCA during the initialization of HC.
CHED[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.
6.8.7.10. HCCONTROLCURRENTED REGISTER
Register Name: HcControlCurrentED[CCED]
Default Value: 0x0
CCED[31:4]
The pointer is advanced to the next ED after serving the present
one. HC will continue processing the list from where it left off in the
last Frame. When it reaches the end of the Control list, HC checks
the ControlListFilled of in HcCommandStatus. If set, it copies the
content of HcControlHeadED to HcControlCurrentED and clears
the bit. If not set, it does nothing.
HCD is allowed to modify this register only when the
ControlListEnable of HcControl is cleared. When set, HCD only
reads the instantaneous value of this register. Initially , this is set to
zero to indicate the end of the Control list.
CCED[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.
6.8.7.11. HCBULKHEADED REGISTER
Register Name: HcBulkHeadED[BHED]
Default Value: 0x0
BHED[31:4]
The HcBulkHeadED register contains the physical address of the
first Endpoint Descriptor of the Bulk list. HC traverses the Bulk list
starting with the HcBulkHeadED pointer. The content is loaded
from HCCA during the initialization of HC.
BHED[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
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