
CHAPTER 14 USBU (UNIVERSAL SERIAL BUS UNIT)
User’s Manual U14579EJ2V0UM
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14.3 Operational Registers
The USBU (USB host controller, HC) has on-chip operational registers, which are windows for communicating with
the host CPU. These registers, which are mapped to a 4 KB range of the system’s 4 GB main memory space, are
used by the host controller driver (HCD). All of these registers are read/written in units of words. The CPU is accessed
according to a PC memory cycle via the internal PCI bus. The base address is indicated by the base address register
of the USB host control configuration space.
For more detailed information, refer to the OPEN HCI Specification Release 1.0.
14.3.1 Register set
Table 14-2 lists the host control operational registers.
Table 14-2. Host Control Operational Registers
Offset
Address
R/W
(HCD)
R/W
(HC)
Register Symbol
Function
0x00
R
HcRevision
HC revision register
0x04
R/W
HcControl
HC control register
0x08
R/W
HcCommandStatus
HC command register
0x0C
R/W
HcInterruptStatus
HC interrupt request detection register
0x10
R/W
R
HcInterruptEnable
HC interrupt request enable register
0x14
R/W
R
HcInterruptDisable
HC interrupt request disable register
0x18
R/W
R
HcHCCA
HC base address register
0x1C
R
R/W
HcPeriodCurrentED
HC period current ED register
0x20
R/W
R
HcControlHeadED
HC control list 1st ED register
0x24
R/W
HcControlCurrentED
HC control list current ED register
0x28
R/W
R
HcBulkHeadED
HC bulk list 1st ED register
0x2C
R/W
HcBulkCurrentED
HC bulk list current ED register
0x30
R
R/W
HcDoneHead
HC last TD register
0x34
R/W
R
HcFmInterval
HC frame interval register
0x38
R/W
HcFmRemaining
HC frame bit time remaining register
0x3C
R/W
HcFmNumber
HC frame counter register
0x40
R/W
R
HcPeriodicStart
HC list processing start register
0x44
R/W
R
HcLSThreshold
HC low speed transfer diagnosis register
0x48
R/W
R
HcRhDescriptorA
HC power supply status register A
0x4C
R/W
R
HcRhDescriptorB
HC power supply status register B
0x50
R/W
HcRhStatus
HC status register
0x54
R/W
HcRhPortStatus1
HC port status register 1
0x58
R/W
HcRhPortStatus2
HC port status register 2
These registers are described in detail below.