ISD-200 Datasheet, PDF (14/64 Pages) List of Unclassifed Manufacturers – USB Mass Storage Class Bulk-Only Specification Compliant

ISD-200 ASIC Datasheet
Serial ROM I_MODE
present
Input Pin
No
1
Yes
0
Yes
1
ISD-200 Configuration and USB Descriptor Retrieval
internal on-board ROM.
The ISD-200 retrieves all Descriptor and Configuration values from the
vendor-specific Identify (FBh) data. The ISD-200 is configured using
values in the internal ROM until the FBh data becomes available
The ISD-200 retrieves all Descriptor and Configuration values from
serial ROM. The ISD-200 is configured using values present in serial
ROM data only (Unless the serial ROM signature check fails. The ISD-
200 then uses POR defaults listed in the Descriptor and Configuration
data sections of this document).
Undefined mode of operation.
Table 2 – ISD-200 Configuration and Descriptor Sources
Internal ROM Contents
Internal on-board ROM addresses and the contents of those locations are shown in Tables 3 and 7 to 11. If
the ISD-200 is operated using the on-board ROM contents for descriptor data, the Serial Number string is
still guaranteed to be unique, as required by the USB Mass Storage Class (MSC) Bulk Only Transport
Specification, through the utilization of a DIE-ID process at fabrication. This unique identifier is generated
through the usage of physical parameters such as wafer coordinates, wafer number, lot number, fab
number, date, time, etc.
The internal ROM is also convenient for prototyping and manufacturing activities. Enough information is
supplied from the internal ROM to the host that the ISD-200 will enumerate even when an un-programmed
serial ROM is connected.
Serial ROM Interface
The ISD-200 supports the I²C “fast mode” interface, as found in the 24(L)C01-16 EEPROM family. That
device family allows for up to 4 Kbytes of external storage, which may be used to store descriptors and
other information. Note that if a 24(L)C04/08/16 part is used, no descriptor is allowed to span multiple
pages within the EEPROM.
Programming of the serial ROM can be accomplished using an external device programmer, ISD-200
supported vendor specific USB commands, or using a “bed of nails” while the ISD-200 is in LIMBO Test
mode (See Operational Modes, Test Mode Pins). An example of Serial ROM formatting is shown in
Appendix A. Unused space in a serial ROM may be used for other purposes using the
LOAD_CONFIG_DATA and READ_CONFIG_DATA USB Requests.
Hardware detects the presence of a serial ROM and, if one is present, performs a data validity check. This
check is in the form of a ‘signature’ and is located at the beginning of the serial ROM data (Addresses 0x0
– 0x1, Table 3). If none is detected or the signature check fails, the ISD-200 will return configuration and
descriptor data from the internal on-board ROM.
Vendor-Specific Identify (FBh) Data
If a serial ROM is not used, the ISD-200 can be configured to accept Descriptor and Configuration data
from an attached device using a vendor-specific Identify command during the boot sequence. (See
Operational Modes, I_MODE Pin)
For FBh data to be deemed valid, it must first pass a validity check. This check is in the form of a
‘signature’ and is located at the beginning of the FBh data (Addresses 0x0 – 0x1, Table 3). In the event of
a failed signature check, the ISD-200 will respond to all Get_Descriptor or Get_Configuration USB
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