ADSP-BF535 Blackfin Processor Hardware Reference
14-61
USB Device
Isochronous Transfers Error Detection
While Control, Interrupt, and Bulk data transfers support a method for
error correction, Isochronous transfers have only error detection capabil-
ity. Occasionally, the device can expect that an entire packet is lost, but in
most cases, the device has to deal with CRC errors or bitstuff violations.
In these cases, the entire packet transfers, but the application is responsi-
ble for determining how to handle the error.
Under normal circumstances, the USBD module generates both
end-of-packet and end-of-transfer interrupts (
USBD_PC
,
USBD_TC
) for iso-
chronous packets.
If an error occurs (for example, CRC error, or bitstuff error), the module
still asserts the
USBD_TC
, but it does not assert the
USBD_PC
. In this way, the
application can detect and compensate for errors.
Reset Signaling Detected on USB
USB reset signaling is generated by the USB host. The Host uses reset sig-
naling when it needs to re-enumerate devices on the bus. This can occur
just after power-up, when devices are initially connected to a hub port,
and any time the USB host runs into a catastrophic failure situation.
The USBD module reports the presence of USB reset signaling to the sys-
tem through the
USBD_RSTSIG
bit of the
USBD_STAT
register and by means
of the
USBD_RST
interrupt of the
USBD_GINTR
register.
When the system detects one of these cases, it should terminate any activi-
ties currently in progress and prepare for the device to be re-enumerated
by the USB host. The system does not need to re-download the UDC end-
point buffer data, nor does it need to reinitialize the device.
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...