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15.5.10 Processing of USB Standard Commands and Class/Vendor Commands
(1) Processing of Commands Transmitted by Control Transfer
A command transmitted from the host by control transfer may require decoding and execution
of command processing by the firmware. Whether or not command decoding is required by the
firmware is indicated in table 15.6 below.
Table 15.6 Command Decoding on Firmware
Decoding not Necessary on Firmware
Clear Feature
Get Configuration
Get Interface
Get Status
Set Address
Set Configuration
Set Feature
Set Interface
If decoding is not necessary on the firmware, command decoding and data stage and status
stage processing are performed automatically. No processing is necessary by the user. An
interrupt is not generated in this case.
If decoding is necessary on the firmware, the USB function module stores the command in
the EP0s FIFO. After normal reception is completed, the SetupTS flag of UIER0 is set and an
interrupt request is generated from the EXIRQx. In the interrupt routine, eight bytes of data
must be read from the EP0s data register (UEDR0s) and decoded by firmware. The necessary
data stage and status stage processing should then be carried out according to the result of the
decoding operation.
15.5.11 Stall Operations
(1) Overview
This section describes stall operations in the USB function module. There are two cases in
which the USB function module stall function is used:
1. When the firmware forcibly stalls an endpoint for some reason
2. When a stall is performed automatically within the USB function module due to a USB
specification violation
Rev. 3.0, 10/02, page 508 of 686
Decoding Necessary on Firmware
Get Descriptor
Synch Frame
Set Descriptor
Class/Vendor command
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