TMP92CZ26A

92CZ26A-432

(c-4) Stage management
UDC manages each stage of control transfer by hardware.
Each stage is changed by receiving token from USB host, or CPU accesses
register. Each stage in control transfer type has to process combinat ion sof twa re .
UDC detect following contents from 8-byte data in SETUP stage. (It contents is
showed to followin g.) And, stage is managed by judging control transfer type.
There is data stage or not
Data stage direction
Control read transfer typ e is jugge d co ntrol write transfer type, contr ol wr ite
transfer type (No data stage) by them.
Below are various conditions for changin g stage in control transfer.
If receiving token for next stage from host before switching next stage from
state of internal UD C, NAK handshake is returned and BUSY is informed t o USB
host. In all control transfer type, if SETUP token is received from host always,
present transaction is stopped, and it switch es SETUP stage in UDC. CPU receiv e
new INT_SETUP even if it is processing previous control transfer.