Specifications

V850E2/MN4 USB CDC (Communication Device Class) Driver
R01AN0010EJ0101 Rev.1.01 Page 11 of 117
Feb 01, 2012
3.4 Requests
According to the USB specification, communication is initiated by the host device issuing a command called a request
to all function devices. The request contains data such as the direction and type of processing and the address of the
target function device. Each function device decodes the request, determines whether the request is directed to itself,
and responds to the request only when it is directed to the device.
3.4.1 Types
There are three types of requests, namely, the standard requests, class requests, and vendor requests.
See section 4.1.2, Requests Handling, for the requests that the sample driver support.
(1)
Standard Requests
Standard requests are used in common by all USB compatible devices. A request is a standard request when both bits 6
and 5 of the bmRequestType field of the request are set to 0. Refer to the USB specification (Universal Serial Bus
Specification Rev. 2.0) for the processing that is to be performed for the standard requests.
Table 3.2 List of Standard Requests
Request Name Target Descriptor Outline
Device
Read power (self or bus) and remote wakeup
settings.
GET_STATUS
Endpoint Read Halt status.
Device Clear remote wakeup. CLEAR_FEATURE
Endpoint Cancel Halt (DATA PID = 0).
Device Set up remote wakeup or test mode. SET_FEATURE
Endpoint Set Halt
GET_DESCRIPTOR Device, configuration, string Read target descriptor
SET_DESCRIPTOR Device, configuration, string Set target descriptor (optional)
GET_CONFIGURATION Device Read current configuration value.
SET_CONFIGURATION Device Set configuration value.
GET_INTERFACE Interface
Read alternate value out of the current settings
of the target interface.
SET_INTERFACE Interface Set alternate value of the target interface.
SET_ADDRESS Device Set USB address.
SYNCH_FRAME Endpoint Read frame-synchronous data.