| A1 |
When developing USB peripherals, the following items must be taken into consideration.
(1) Compliance with USB standard
(2) Public certification as USB device
(3) General versatility not dependent on type of equipment that is connected
Regarding (1)
Compliance with the USB standard as silicon has been guaranteed through the Data Sheet.
Configuration of a hub as a system and whether the hub satisfies the conditions of a USB device depends
on the vendor that designs the system.
In other words, the vendor must perform checks at the board level and at the system level
to verify standard compliance.
This requires an understanding of the specification contents.
However, the majority of vendors perform simple testing that only checks
whether the developed USB peripheral functions normally when connected to a PC with USB capability,
and if yes, assume that the designed USB device functions.
However, such as check consists only in verifying operation under limited conditions,
and is insufficient for determining whether the designed USB device complies with the USB standard.
What is required is a point-by-point check of compliance with the USB standard, as well as observance of the points outlined for (2) below.
Regarding (2)
It is necessary to pass the certification test recommended by USB-IF, which is a USB device certification body
(the certification methods are to participate in PlugFesta and pass its test,
or request a test during the recommended certification period), upon which one obtains the right to use the appropriate USB-IF logo with that product.
Moreover, if use as a Windows-compliant device is recommended,
it is also necessary to participate in a test program (WHQL test)
administered by Microsoft to receive certification.
Actually, to receive the above certifications, it is necessary to obtain IDs for each vendor.
(Concretely, the necessity for ID obtainment varies on the configuration of the designed device: The number of ports from the hub,
whether the hub ports are used internally in the device, the type of power topology, etc.)
If use as a Windows peripheral is assumed,
the current trend among recent Microsoft products is to support only devices whose operation has been certified by Microsoft,
and to reject all other devices at the driver level as unknown devices.
Therefore, taking future operation into consideration, it is safer to obtain an ID,
regardless of the product configuration.
* The operation on the existing OS was problem-free, but problems may arise as the result of OS updates, etc.
** The uPD72012-003 is officially recognized as a "hub with 4 detachable ports."
If the port configuration changes, please obtain a new ID.
(3) The term USB device implies responsibility for guaranteeing intercompatibility with other USB-compatible products such as PCs and USB devices.
(If a device does not guarantee intercompatibility, it cannot be called a USB device.)
Since the USB-IF testing provides more rigorous assurance, logo certification is strongly recommended,
and unrecognized devices should be rejected.
In other words, devices that have been logo certified are recognized as USB devices with high versatility in the sense
that they have passed the USB-IF test.
As a core member of the USB Implementers Forum, NEC Electronics recommends logo certification.
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