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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262--, Revision: 004US
493
USB 2.0 Host Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
test_packet[42]=0xFB; test_packet[43]=0xFD; test_packet[44]=0xFC;
test_packet[45]=0x7E; test_packet[46]=0xBF; test_packet[47]=0xDF;
test_packet[48]=0xEF; test_packet[49]=0xF7; test_packet[50]=0xFB;
test_packet[51]=0xFD; test_packet[52]=0x7E;
5. Write Run/Stop and Asynchronous Schedule Enable (USBCMD Register) to their
active states. Test packets will begin being sent continuously and SOFs will be
suppressed.
To stop Test packet generation, first write Run/Stop and Asynchronous Schedule
Enable to their inactive states. After HCHALTED (USBSTS Register) is active, then the
QH can be removed and Port Test Control can be reprogrammed because Test
Packets will have ceased.
9.16
Compatibility
This USB host is compatible with the USB 2.0 standard with the exception that it does
not support a High Speed electrical interface.
9.17
Power-Management Requirements
The core is a fully synchronous static design. The power used by the design is
dependent on the application usage of the core. Applications that transfer more data or
use a greater number of packets to be sent will consume a greater amount of power.
9.17.1
USB Power States
The USB provides a mechanism to place segments of the USB or the entire USB into a
low power suspend state. USB bus powered devices are required to respond to a 3ms
lack of activity on the USB bus by going into a suspend state. In the USB core, software
is notified of the suspend condition via the transition in the PORTSC register, optionally
an interrupt can be generated which is controlled by the port change Detect Enable bit
in the VSBINTR control register. Software then has 7 ms to transition a bus powered
device into the suspend state. In the suspend state, a USB device has a maximum USB
bus power budget of 500 µA.
9.17.2
Host Power States
The USB Host core does not support power-down states.
9.18
Error/Abnormal Conditions
There are two error conditions of interest, ABH errors and overrun/underflow.
The second condition can occur when the host controller does not have sufficient
bandwidth or latency of access to memory and the real-time processing of a packet.
The USB specification comprehends this case and in the extremely unlikely event it
should occur, an outbound packet is corrupted to cause a Device NAK and an inbound
packet will be NAKed. If the packet is a bulk transfer, it will be retried, and if the packet
is an ISO transfer, it will be permanently lost. Both conditions are consistent with the
USB 2.0 specification.
The first condition is not readily comprehended by the USB specification per se as it is
an implementation specific case. There are two cases where the AHB will return an
error response, an out-of-range address and a parity or double bit DRAM error. In the
case of an out-of-range address, the cause is a software fault and is fatal. The software
should not chain control blocks to non-existent memory so an out-of-range address is a
clear indication of a software bug. In the case of a parity or double bit SRAM error, the