
ISD-300A1
22
October 19, 2001
The Bulk Out pipe is used to send commands and data to an attached mass storage device. Maximum
packet size is 64 bytes in FS operation, 512 bytes in HS operation.
Bulk In Pipe
The Bulk In pipe is used to receive status and read data from an attached mass storage device. Maximum
packet size is 64 bytes in FS operation, 512 bytes in HS operation.
Interrupt Pipe
The Interrupt pipe implemented in the ISD-300A1 serves two purposes: 1) Some legacy software
applications require the endpoint to exist for correct operation, and 2) to enable systems to request service
by the host. For more information, see the
SYS_IRQ Pin
section on page 41 of this document.
Requests
The ISD-300A1 responds to three different types of request:
Standard USB device requests
Mass Storage Class Bulk-Only requests
Vendor-specific requests
Standard Requests
The ISD-300A1 supports all USB standard device requests except the optional Set Descriptor request.
These requests, which are described in Chapter 9, Device Framework, of the
USB Specification
, are:
Clear Feature
Get Configuration
Get Descriptor (for information on String Descriptors, see
String Descriptors
on page 19)
Get Interface
Get Status
Set Address
Set Configuration
Set Interface
Set Feature
Mass Storage Class Bulk-Only Requests
Mass Storage Class Bulk-Only requests supported by the ISD-300A1 are listed in
Table 11
.
Label
bmRequestType
bRequest
RESET
0x21
0xFF
GET_MAX_LUN
0xA1
0xFE
wValue
0x0000
0x0000
wIndex
Interface
Interface
wLength
0x0000
0x0001
Data
[None]
1 byte
Table 11 – Mass Storage Class Bulk-Only Requests
RESET
This request flushes all buffers and resets the pipes to their default states, resets all hardware registers to
their default state, and basically causes the ISD-300A1 to enter a power-up reset state. Any STALL
conditions or bulk data toggle bits remain unchanged.
GET_MAX_LUN
The ISD-300A1 returns one byte of data that contains the maximum LUNs supported by the device. This
information is derived from the Last LUN Identifier configuration setting, bits (2:0) of configuration data
located at address offset 0x8. For example, if the device supports four LUNs then the LUNs would be