ADSP-BF535 Blackfin Processor Hardware Reference
14-31
USB Device
USB Endpoint x Control Registers (USBD_EPCFGx)
The USB Endpoint x Control registers, shown in
Figure 14-18
, allow pro-
gramming the characteristics of individual endpoints.
The
USBD_ARM
bit is set to 1 to arm an endpoint. When the endpoint is
armed, the USBD module can respond to transfer requests on the
endpoint. If
USBD_ARM = 1
and
USBD_BC = 0
, then the module generates a
0-length data packet. This bit clears automatically when
USBD_BC
decre-
ments to 0 or when an end-of-transfer condition is detected.
The
USBD_ARM
bit is set to 0 to disarm an endpoint. If a packet transfer is
in progress, clearing this bit does not stop the current packet transfer, but
it does prevent succeeding packets in a multipacket transfer from occur-
ring. For example, consider a 64-byte packet, 128-byte count. If the
system clears
USBD_ARM
during the transfer of the first packet, then the first
packet completes normally, but the second one is unable to transfer until
the endpoint is armed again.
The
USBD_DIR
bit indicates the transfer direction between the USB device
and the USB host. If the USB host requests a packet transfer and the
direction of the request does not agree with the endpoint direction, then
the module NAKs the current packet. This can occur on USB control
transfers when the endpoint is set to OUT for the setup packet and the
USB host requests an IN data-phase packet before the device has recog-
nized the presence of the setup packet.
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...