Transaction
Scheduled
TxPktRdy
and SetupPkt
Both Set?
SETUP Token Sent
STALL
Received?
Yes
RxStall Set
TxPktRdy Cleared
Error Count Cleared
Interrupt Generated
Command Not
Supported By Target
No
ACK
Received?
No
Yes
No
NAK Limit
Reached?
Yes
Yes
No
No
NAK Timeout Set
Endpoint Halted
Interrupt Generated
NAK
Received?
Error Count
Incremented
Transaction
Complete
Implies Problem at
Peripheral End of
Connection
Transaction Deemed
Completed
Error Bit Set
TxPktRdy Cleared
Error Count Cleared
Interrupt Generated
Yes
Error Count
= 3?
TxPktRdy Cleared
Error Count Cleared
Interrupt Generated
Error Count
Cleared
DATA0 Packet Sent
Yes
No
Functional Description
Figure 16-8. Flow Chart of Setup Stage of a Control Transfer in Host Mode
16.3.8.2.1.2 Data Phase (IN Data Phase) of a Control Transaction: Host Mode
For the IN Data Phase of a control transaction (
), the software driving the USB host device
needs to
1. Set REQPKT bit of HOST_CSR0 (bit 5)
2. Wait while the controller sends the IN token and receives the required data back.
3. When the controller generates the Endpoint 0 interrupt, read HOST_CSR0 to establish whether the
RXSTALL bit (bit 2), the ERROR bit (bit 4), the NAK_TIMEOUT bit (bit 7) or RXPKTRDY bit (bit 0) has
been set.
If RXSTALL is set, it indicates that the target has issued a STALL response.
1720
Universal Serial Bus (USB)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated