Cypress CY7C68023, CY7C68024 manual Applications, Functional Overview, Enumeration

CY7C68023/CY7C68024

4.0Applications

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.

4.1Additional 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.

5.0Functional Overview

5.1USB 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.

5.2NAND 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.

6.0Enumeration

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.

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.

Start-up

Yes	NAND Flash	No
	Present?
NAND Flash	No
Programmed?
Yes

Load Custom	Load Default
Descriptors and	Descriptors and
Configuration Data	Configuration Data

Enumerate As	Enumerate As
USB Mass	Generic NX2LP
Storage Device	Device

6.1Normal 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.

6.2Manufacturing 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.

Normal Operation	Manufacturing
Mode	Mode

Figure 6-1. NX2LP Enumeration Process

6.3Configuration 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 6-1lists 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.

Document #: 38-08055 Rev. *B Page 5 of 9

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