HID Functions for Button Controls

CY7C68300C/CY7C68301C

CY7C68320C/CY7C68321C

Cypress’s CY7C68320C/CY7C68321C has the capability of supporting Human Interface Device (HID) signaling to the host.

If there is a HID descriptor in the configuration data, the GPIO pins that are set as inputs are polled by the AT2LP logic approximately every 17 ms (depending on other internal interrupt routines). If a change is detected in the state of any HID-enabled GPIO, an HID report is sent through EP1 to the host. The report format for byte 0 and byte 1 are shown in Table 5.

The ability to add buttons to a mass storage solution opens new applications for data backup and other device-side notifi- cation to the host. The AT2LP Blaster software, found in the

Table 5. HID Data Bitmap

CY4615C files, provides an easy way to enable and modify the HID features of the AT2LP.

GPIO pins can be individually set as inputs or outputs, with byte 0x09 of the configuration data, allowing for a mix of HID and general purpose outputs. GPIOs that are not configured as inputs are reported with a value of ‘0’ in the HID data. The RESERVED bits’ values must be ignored, and Cypress recom- mends using a bitmask in software to filter out unused HID data.

Note that if using the 56-pin package, the reported GPIO[5:3] values must be ignored because the pins are not actually present.

		USB Interrupt Data Byte 1								USB Interrupt Data Byte 0
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
RESERVED	RESERVED	RESERVED	RESERVED	RESERVED	RESERVED	USB High-Speed	VBUS Powered	RESERVED	RESERVED	GPIO[5]	GPIO[4]	GPIO[3]	GPIO[2]	GPIO[1]	GPIO[0]

Functional Overview

Chip functionally is described in the subsequent sections.

USB Signaling Speed

AT2LP operates at the following two 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.

AT2LP does not operate at the low-speed signaling rate of 1.5 Mbits/sec.

ATA Interface

The ATA/ATAPI port on the AT2LP is compatible with the Infor- mation Technology–AT Attachment with Packet Interface–6(ATA/ATAPI-6) Specification, T13/1410D Rev 2a. The AT2LP supports both ATAPI packet commands as well as ATA commands (by use of ATA Command Blocks), as outlined in “ATA Command Block (ATACB)” on page 15. Refer to the USB Mass Storage Class (MSC) Bulk Only Transport (BOT) Speci- fication for information on Command Block formatting.

Additionally, the AT2LP translates ATAPI SFF-8070icommands to ATA commands for seamless integration of ATA devices with generic Mass Storage Class BOT drivers.

ATA Command Block (ATACB)

The ATA Command Block (ATACB) functionality provides a means of passing ATA commands and ATA register accesses to the attached device for execution. ATACB commands are transferred in the Command Block Wrapper Command Block (CBWCB) portion of the Command Block Wrapper (CBW). The ATACB is distinguished from other command blocks by having the first two bytes of the command block match the bVSCBSignature and bVSCBSubCommand values that are defined in Table 6. Only command blocks that have a valid bVSCBSignature and bVSCBSubCommand are interpreted as ATA Command Blocks. All other fields of the CBW and restrictions on the CBWCB remain as defined in the USB Mass Storage Class Bulk-Only Transport Specification. The ATACB must be 16 bytes in length. The following table and text defines the fields of the ATACB.

Document 001-05809 Rev. *A

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