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SA-1110 Developer’s Manual 269
Peripheral Control Module
Figure 11-21. Control Transaction Formats
A “transfer” is composed of transactions. A Control “transfer” is composed of a Control
transaction followed by Bulk transactions. To assemble a Control “transfer”, the Host first sends a
“control-read” or “control-write” Control transaction to the SA-1110 UDC’s Endpoint 0. The Host
then receives (if control-read was sent) or transmits (if control-write was sent) one or more Bulk
transactions.
The SETUP Token Packet is the first stage of the Control transaction. The SA-1110 UDC must
respond with an ACK Handshake Packet or, if the SA-1110 UDC detected an error, no Handshake
Packet. The Control transaction, by default, uses a DATA0 Data Packet. Each subsequent Bulk
transaction toggles between using DATA1 and DATA0 Data Packets. A “control-write” Control
transaction to the SA-1110 UDC’s Endpoint 0 is followed by OUT Bulk transactions; a
“control-read” Control transaction to Endpoint 0 is followed by IN Bulk transactions. The SA-1110
UDC supports zero-length DATA1 and DATA0 Data packets.
The last Bulk transaction of a Control “transfer” serves as a Handshake Packet. It always uses a
DATA1 Data Packet even if the previous Bulk transaction used a DATA1 Data Packet. The
direction of this last Bulk transaction is reversed from that of the immediately previous Bulk
transaction, e.g., a Control “transfer” that begins with a “control-read” Control transaction ends
with an OUT Bulk transaction, a Control “transfer” that begins with a “control-write” Control
transaction ends with an IN Bulk transaction.
Interrupt Transactions
:
The SA-1110 UDC responds to a Host-generated Interrupt transaction in the same manner that it
responds to a Bulk transaction.
11.8.1.7 SA-1110 UDC Device-Request Commands
The SA-1110 UDC’s control, status, and data registers are used only to control and monitor the
transmit and receive FIFOs for Endpoint 1 and Endpoint 2. All other SA-1110 UDC configuration
and status reporting is controlled by the Host via the USB bus, where the Host sends
Action Token Packet Data Packet Handshake Packet
SA-1110 UDC successfully received control
from Host
SETUP DATA0 ACK
SA-1110 UDC temporarily unable to receive
data
SETUP DATA0 NAK
SA-1110 UDC endpoint needs Host
intervention
SETUP DATA0 STALL
SA-1110 UDC detected PID, CRC, or bit
stuff error
SETUP DATA0
None
Packets from SA-1110 UDC to Host are boldface