
NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 719 -
Revision V1.30
NUC97
0
T
E
CHNIC
A
L
RE
F
E
RE
N
CE
MA
NUA
L
data through the memory interfacing signals. EHCI accepts the data and moves them to the
downstream device.
OHCI Controller
5.23.5.2
AHB Interface
The OpenHCI Host Controller is connected to the system by the AHB bus. The design requires both
master and slave bus operations. As a master, the Host Controller is responsible for running cycles
on the AHB bus to access EDs and TDs as well as transferring data between memory and the local
data buffer. As a slave, the Host Controller monitors the cycles on the AHB bus and determines when
to respond to these cycles. Configuration and non-real-time control access to the Host Controller
operational registers are through the AHB bus slave interface.
AHB Master
The master issues the address and data onto the bus when granted.
AHB Slave
The configuration of the Host Controller is through the slave interface.
List Processing
The List Processor manages the data structures from the Host Controller Driver and coordinates all
activity within the Host Controller.
Frame Management
Frame Management is responsible for managing the frame specific tasks required by the USB
specification and the OpenHCI specification. These tasks are:
Management of the OpenHCI frame specific Operational Registers
Operation of the Largest Data Packet Counter.
Performing frame qualifications on USB Transaction requests to the SIE.
Generate SOF token requests to the SIE.
Interrupt Processing
Interrupts are the communication method for HC-initiated communication with the Host Controller
Driver. There are several events that may trigger an interrupt from the Host Controller. Each specific
event sets a specific bit in the HcInterruptStatus register.
Host Controller Bus Master
The Host Controller Bus Master is the central block in the data path. The Host Controller Bus Master
coordinates all access to the AHB Interface. There are two sources of bus mastering within Host
Controller: the List Processor and the Data Buffer Engine.