Toshiba TLCS-900/H1 Series Manual page 259

(c-4) Stage management
The 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 combination software.
UDC detects the following contents from 8-byte data in SETUP stage. The stage is
managed by determining control transfer type.
•
Whether there is data stage or not
• Data stage direction
Based on these it is determined to be either control read transfer type, control
write transfer type, or control write transfer type (No data stage).
Various conditions for changing stage in control transfer are given below.
If receiving token for next stage from host before switching to next stage from
state of internal UDC, NAK handshake is returned and BUSY is informed to USB
host. In all control transfer types, if SETUP token is received from host, present
transaction is stopped, and it switches to SETUP stage in the UDC. The CPU
receives new INT_SETUP even if it is processing previous control transfer.
92CH21-257
TMP92CH21
2009-06-19