CY7C68023/CY7C68024
Document #: 38-08055 Rev. *B
Page 5 of 9
4.0
Applications
The NX2LP is a high-speed USB 2.0 peripheral device that
connects NAND Flash devices to a USB host using the USB
Mass Storage Class protocol.
4.1
Additional Resources
• CY3685 EZ-USB NX2LP Development Kit
• CY4618 EZ-USB NX2LP Reference Design Kit
• USB Specification version 2.0
• USB
Mass Storage Class Bulk Only Transport
Specification
,
http://www.usb.org/developers/data/devclass/
usbmassbulk_10.pdf.
5.0
Functional Overview
5.1
USB Signaling Speed
The NX2LP operates at two of the three rates defined in the
USB Specification Revision 2.0 dated April 27, 2000:
• Full speed, with a signaling bit rate of 12 Mbits/sec
• High speed, with a signaling bit rate of 480 Mbits/sec.
The NX2LP does not support the low-speed signaling rate of
1.5 Mbits/sec.
5.2
NAND Flash Interface
During normal operation the NX2LP supports an 8-bit I/O
interface, eight chip enable pins, and other control signals
compatible with industry standard NAND Flash devices.
6.0
Enumeration
During the start-up sequence, internal logic checks for the
presence of NAND Flash with valid configuration data in the
configuration data memory area. If valid configuration data is
found, the NX2LP uses the values stored in NAND Flash to
configure the USB descriptors for normal operation as a USB
mass storage device. If no NAND Flash is detected, or if no
valid configuration data is found in the configuration data
memory area, the NX2LP uses the default values from internal
ROM space for manufacturing mode operation. The two
modes of operation are described in sections 6.1 and 6.2
below.
6.1
Normal Operation Mode
In Normal Operation Mode, the NX2LP behaves as a USB 2.0
Mass Storage Class NAND Flash controller. This includes all
typical USB device states (powered, configured, etc.). The
USB descriptors are returned according to the data stored in
the configuration data memory area. Normal read and write
access to the NAND Flash is available in this mode.
6.2
Manufacturing Mode
In Manufacturing mode, the NX2LP enumerates using the
default descriptors and configuration data that are stored in
internal ROM. This mode allows for first-time programming of
the configuration data memory area, as well as board-level
manufacturing tests.
A unique USB serial number is required for each device in
order to comply with the USB Mass Storage specification.
Also, Cypress requires designers to use their own Vendor ID
for final products. The Vendor ID is obtained through regis-
tration with the USB Implementor’s Forum (USB-IF), and the
Product ID is determined by the designer.
Cypress provides all the software tools and drivers necessary
for properly programming and testing the NX2LP. Please refer
to the documentation in the development or reference design
kit for more information on these topics.
6.3
Configuration Data
Certain features in the NX2LP can be configured by the
designer to disable unneeded features, and to comply with the
USB 2.0 specification’s descriptor requirements for mass
storage devices.
Table 6-1
lists the variable configuration data
and the default values that are stored in internal ROM space.
The default ROM values are returned by an unprogrammed
NX2LP device.
NAND Flash
Programmed?
Load Default
Descriptors and
Configuration Data
Manufacturing
Mode
Load Custom
Descriptors and
Configuration Data
Enumerate As
USB Mass
Storage Device
Normal Operation
Mode
Start-up
Enumerate As
Generic NX2LP
Device
NAND Flash
Present?
No
Yes
Yes
No
Figure 6-1. NX2LP Enumeration Process
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