ADSP-BF535 Blackfin Processor Hardware Reference
14-43
USB Device
USBD_BCSTAT – Buffer Complete
This interrupt asserts when the byte count has counted down to 0 for an
endpoint. Software can examine the
USBD_EPADRx
and
USBD_EPLENx
regis-
ters to determine the actual progress of the transfer.
USBD_SETUP – Setup Packet Received
This interrupt asserts when a setup packet is received on the current con-
trol endpoint. See
USBD_MSETUP
below for the device behavior if a
USBD_SETUP
interrupt is already pending and a new one arrives.
USBD_MSETUP – Multiple Setup Packets Received
This interrupt asserts when a
USBD_SETUP
interrupt is already pending and
another setup packet is received, as could happen when the USB device’s
ACK of the first setup packet is not received by the USB host, and the
USB host retransmits the command.
USBD_MERR – Memory Controller Error
This interrupt covers the case of a buffer overrun or underrun. This inter-
rupt sets when the
USBD_BC
interrupt is pending for an endpoint and
another packet request has been received from the USB host for the same
endpoint. When this situation occurs, the USB device is NAKing requests
from the USB host and must correct the situation to ensure maximum
bandwidth usage.
The specific problem here is with OUT packets. Each time the USB host
tries to send a 64-byte packet, for example, it sends the whole packet “in
the blind” assuming that the USB device will accept it. If the USB device
is not ready, then this is wasted bus bandwidth that could be given to
another device which is ready to complete a packet transfer.
Summary of Contents for ADSP-BF535 Blackfin
Page 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Page 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Page 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Page 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Page 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Page 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Page 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Page 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Page 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...