NAK
Received?
NAK Limit
Reached?
NAK Timeout Set
Endpoint Halted
Interrupt Generated
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
Error Count
= 3?
Error Count
Cleared
Completion of
In Data Phase
TxPktRdy
and StatusPkt
Both Set?
No
Yes
OUT Token Sent
Command Could Not
Be Completed
Yes
No
Yes
Zero-Length
DATA1 Packet Sent
STALL
Received?
ACK
Received?
RxStall Set
TxPktRdy Cleared
Error Count Cleared
Interrupt Generated
No
No
No
Yes
Yes
Yes
No
TxPktRdy Cleared
Error Count Cleared
Interrupt Generated
Functional Description
Figure 16-12. Chart of Status Stage of a Read Request of a Control Transfer in Host Mode
16.3.8.2.2 Bulk Transfer: Host Mode
Bulk transactions are handled by endpoints other than endpoint 0. It is used to handle non-periodic, large
bursty communication typically used for a transfer that use any available bandwidth and can also be
delayed until bandwidth is available.
16.3.8.2.2.1 Bulk IN Transactions: Host Mode
A Bulk IN transaction may be used to transfer non-periodic data from the external USB peripheral to the
host.
1726
Universal Serial Bus (USB)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated