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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 438
UG585 (v1.11) September 27, 2016
Chapter 15: USB Host, Device, and OTG Controller
must acknowledge a setup token in the timeliest manner possible to have the control endpoint and
buffer always available for another Setup token. The SOF interrupt is next important.
Low-Frequency Interrupts
The low frequency events include the following interrupts. These interrupt can be handled in any
order since they do not occur often in comparison to the high-frequency interrupts.
Error Interrupts
Error interrupts will be least frequent and should be placed last in the interrupt service routine.
Table 15-17: USB Device High Frequency Interrupt
Execution
Order
Interrupt usb.USBSTS Action
1a
USB Interrupt
ENDPTSETUPSTATUS
[UI]
Copy contents of setup buffer and acknowledge setup packet.
Process setup packet according to USB 2.0 Chapter 9 or
application specific protocol.
1b
USB Interrupt
ENDPTCOMPLETE
[UI] Handle completion of dTD.
2 SOF Interrupt [SRI]
Action as deemed necessary by application. This interrupt might
not have a use in all applications.
Table 15-18: USB Low-Frequency Interrupt
Interrupt usb.USBSTS Action
Port Change [PCI] Change the software state information.
Suspend [SLI] Change the software state information.
Reset Received [URI] Change the software state information. Abort pending transfers.
Table 15-19: USB Device Error Interrupt
Interrupt usb.USBSTS Action
USB Error [UEI]
This error is redundant because it combines USB Interrupt and an
error status in the dTD. The DCD will more aptly handle
packet-level errors by checking dTD status field upon receipt of
USB Interrupt (with ENDPTCOMPLETE).
System Error [SEI]
Unrecoverable error. Immediate Reset of controller, free transfers
buffers in progress and restart the software.