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Spinpoint M8U-Internal Product Manual REV 3.4
71
INSTALLATION
6.3.6.3.7 Set Address (Request Code 5)
This request sets the device address for all future device accesses.
The wValue field specifies the device address to use for all subsequent accesses.
As noted elsewhere, requests actually may result in up to three stages. In the first stage, the Setup packet is
sent to the device. In the optional second stage, data is transferred between the host and the device. In the final
stage, status is transferred between the host and the device. The direction of data and status transfer depends
on whether the host is sending data to the device or the device is sending data to the host. The Status
stage transfer is always in the opposite direction of the Data stage. If there is no Data stage, the Status stage is
from the device to the host.
Stages after the initial Setup packet assume the same device address as the Setup packet. The USB device
does not change its device address until after the Status stage of this request is completed successfully. Note
that this is a difference between this request and all other requests. For all other requests, the operation
indicated must be completed before the Status stage. If the specified device address is greater than 127, or if
wIndex or wLength are non-zero, then the behavior of the device is not specified.
Device response to SetAddress() with a value of 0 is undefined.
Default state: If the address specified is non-zero, then the device shall enter the Address state; otherwise,
the device remains in the Default state (this is not an error condition).
Address state: If the address specified is zero, then the device shall enter the Default state; otherwise, the
device remains in the Address state but uses the newly-specified address.
Configured state: Device behavior when this request is received while the device is in the Configured state
is not specified.
6.3.6.3.8 Set Configuration (Request Code9)
This request sets the device configuration.
The lower byte of the wValue field specifies the desired configuration. This configuration value must be zero
or match a configuration value from a configuration descriptor. If the configuration value is zero, the device is
placed in its Address state. The upper byte of the wValue field is reserved.
If wIndex, wLength, or the upper byte of wValue is non-zero, then the behavior of this request is not specified.
Default state: Device behavior when this request is received while the device is in the Default state is not
specified.
Address state: If the specified configuration value is zero, then the device remains in the Address state. If the
specified configuration value matches the configuration value from a configuration descriptor, then that
configuration is selected and the device enters the Configured state. Otherwise, the device responds with a
Request Error.
Configured state: If the specified configuration value is zero, then the device enters the Address state. If the
specified configuration value matches the configuration value from a configuration descriptor, then that
configuration is selected and the device remains in the Configured state. Otherwise, the device responds with
a Request Error.
6.3.6.3.9 Set Descriptor (Request Code 7)
This request is optional and may be used to update existing descriptors or new descriptors may be added.