RM0082
HS_USB 2.0 device
Doc ID 018672 Rev 1
493/844
[12]
DEVNAK
1'h0
NAK handshake.
setting this bit, the udc-ahb Subsystem returns a NAK
handshake to all out endpoints, avoiding then to set the
SNAK bit of each endpoint control register (
[11]
SCALE
1'h0
Scale down.
Setting this bit, the timer values inside the UDC-AHB
subsystem are scaled down when running gate-level
simulation only, aiming to reduce simulation time. Clear the
bit for normal operation.
[10]
SD
1'h0
Soft disconnect.
This bit is used by the software application to signal the UDC
to soft-disconnect. In particular, setting this bit causes the
UDC-AHB Subsystem to enter the disconnected state.
[09]
MODE
1'h0
Operation mode.
This bit allows to select the operation mode of the UDC-AHB
subsystem (
Theory of operation on page 470
encoding:
1‘b0 = slave-only mode.
1‘b1 = DMA mode.
[08]
1'h0
Burst transfer to AHB bus enable.
Setting this bit, the DMA burst split (
) is enabled, and burst length is programmed by
the BRLEN field in this register.
[07]
THE
1'h0
Thresholding enable.
Setting this bit, the DMA threshold (
) is enabled, and a number of quadlets equal to the
threshold value (field THLEN in this register) are transferred
from the RxFIFO to the memory in an out transaction in
DMA mode.
[06]
1'h0
Buffer fill mode enable.
Setting this bit, the DMA buffer fill mode (
) is enabled, and the data are transferred
into contiguous locations pointed to by the buffer address.
[05]
BE
1'h0
Endianness bit.
Setting this bit, the system byte ordering can be changed
from little endian (default, BE set to 1‘b0) to big endian.
Note: Only data accesses are endian-sensitive (in both
slave-only and DMA mode). Descriptor and CSR accesses
are always in little endian mode.
[04]
1'h0
Descriptor update.
Setting this bit, the DMA updates the descriptor at the end of
each packet processed.
[03]
TDE
1'h0
DMA transmission.
Setting this bit, the transmit DMA is enabled.
Table 401.
Device control register bit assignments (continued)
Bit
Name
Reset value
Description