Texas Instruments OMAP5912 Reference Manual page 1429

Table 55.
Autodecoded Versus Non-Autodecoded Control Requests
Request Recipient
GET/SET Interface
INTERFACE
SYNCH_ Endpoint
FRAME
Notes: 1) Transactions on endpoints other than zero are ignored if the device is not configured (addressed state).
2) If some endpoints are not used by the interface currently set, transactions on these endpoints are not ignored;
the MPU must set halt feature for the endpoint. This does not happen if USB host works correctly.
3) If endpoint 0 is halted, per USB 1.1 Specification (see 9.4.5: Get_Status), all requests are stalled except
GET_STATUS, CLEAR_FEATURE, and SET_FEATURE requests.
4) Requests are handled with respect to USB 1.1 when specified as such, but many device reactions are not speci-
fied by USB 1.1.
5) During a SET_ADDRESS autodecoded command, only the 7 LSBs are significant for the new address (decimal
value from 0 to 127); all others are discarded.
3.7.6 Note on Control Transfers Data Stage Length
SPRU761A
Status MPU Required Action
Non- The MPU must stall the
autodecoded command (via
SYSCON2.STALL_
CMD bit) if interface/setting
number is not correct.
If the request is SET_
INTER-FACE, the MPU must
reset endpoints used by the
interface and halt endpoints not
used by the interface setting
before allowing status stage to
complete.
Non- The MPU must stall the
autodecoded command if it does not support
SYNCH_FRAME request, else
write requested data in the
endpoint 0 FIFO.
The control transfer data stage length is indicated in the setup data packet.
During control reads, if the USB host requests more data than indicated in the
setup packet, unexpected IN transaction is STALLed, causing STALL
handshake for all remaining transactions of the transfer until next SETUP. If
the USB host requires less data than indicated in the setup packet, the transfer
is not STALLed. However, if the host moves to status stage earlier than
expected for a non-autodecoded request, the OUT status stage is NAKed
because the MPU has not enabled the RX FIFO.
USB Device Controller
(Continued)
Device Behavior if
Device Is Not Configured
Command is passed to the
MPU.
Command is passed to the
MPU.
Universal Serial Bus (USB) 137