SA1110 Datasheet, PDF (242/406 Pages) Intel Corporation – Intel StrongARM SA-1110 Microprocessor

Peripheral Control Module
Figure 11-22. Control Transaction Formats
Action
UDC successfully received control from host
Token Packet
SETUP
Data Packet
DATA0
Handshake Packet
ACK
UDC temporarily unable to receive data
SETUP
DATA0
NAK
UDC endpoint needs host intervention
SETUP
DATA0
STALL
UDC detected PID, CRC, or bit stuff error
SETUP
DATA0
None
Packets from UDC to host are boldface
Control transfers are assembled by the host by first sending a control transaction to tell the UDC
what type of control transfer is taking place (control read or control write), followed by two or
more bulk data transactions. The control transaction, by default, uses a DATA0 transfer, and each
subsequent bulk data transaction toggles between DATA1 and DATA0 transfers. For a control write
to an endpoint, OUT transactions are used. For control reads, IN transactions are used. The transfer
direction of the last bulk data transaction is reversed. It is used to report status and functions as a
handshake. The last bulk data transaction always uses a DATA1 transfer by default (even if the
previous bulk transaction used DATA1). For a control write, the last transaction is an IN from the
UDC to the host, and for a control read, the last transaction is an OUT from the host to the UDC.
11.8.1.7 UDC Device Requests
The UDC’s control, status, and data registers are used only to control and monitor the transmit and
receive FIFOs for endpoints 2 and 3. All other UDC configuration and status reporting is controlled
by the host via the USB bus using device requests that are sent as control transactions to endpoint
0. Each setup packet to endpoint 0 is 8 bytes long and specifies:
• Data transfer direction: host to device, device to host
• Data transfer type: standard, class, vendor
• Data recipient: device, interface, endpoint, other
• Number of bytes to transfer
• Index or offset
• Value: used to pass a variable-sized data parameter
• Device request
Table 11-12 shows a summary of all device requests. Users should refer to the Universal Serial Bus
Specification Revision 1.0 for a full description of host device requests.
Table 11-12. Host Device Request Summary
Request
Name
SET_FEATURE
CLEAR_FEATURE
SET_CONFIGURATION
Used to enable a specific feature such as device remote wake-up and
endpoint stalls.
Used to clear or disable a specific feature.
Configures the UDC for operation. Used following a reset of the SA-1110 or
after a reset has been signalled via the USB bus.
11-62
SA-1110 Developer’s Manual