UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
704 of 1269
NXP Semiconductors
UM10503
Chapter 26: LPC43xx Ethernet
26.6.27 DMA Bus mode register
The Bus Mode register establishes the bus operating modes for the DMA.
Table 559. Time stamp status register (TIMESTAMPSTAT, address 0x4001 0728) bit
description
Bit
Symbol
Description
Reset
value
Access
0
TSSOVF
Time stamp seconds overflow
When set, indicates that the seconds value of the time
stamp (when supporting version 2 format) has
overflowed beyond 0xFFFF_FFFF.
0
R/W
1
TSTARGT Time stamp target reached
When set, indicates the value of system time is greater
or equal to the value specified in the Target Time High
and Low registers
0
R/W
31:2
-
Reserved.
-
-
Table 560. DMA Bus mode register (DMA_BUS_MODE, address 0x4001 1000) bit description
Bit
Symbol
Description
Reset
value
Access
0
SWR
Software reset
This register field can be read by the application (Read), can be set to 1 by the
application with a register write of 1 (Write Set), and is cleared to 0 by the Ethernet
core (Self Clear). The application cannot clear this type of field, and a register write of
0 to this bit has no effect on this field.
When this bit is set, the MAC DMA Controller resets all MAC Subsystem internal
registers and logic. It is cleared automatically after the reset operation has completed
in all of the core clock domains. Read a 0 value in this bit before re-programming any
register of the core.
Remark:
The reset operation is completed only when all the resets in all the active
clock domains are de-asserted. Hence it is essential that all the PHY inputs clocks
(applicable for the selected PHY interface) are present for software reset completion.
0
R/W
1
DA
DMA arbitration scheme
0 = Round-robin with Rx:Tx priority given in bits [15:14]
1 = Rx has priority over Tx
0
R/W
6:2
DSL
Descriptor skip length
This bit specifies the number of Word to skip between two unchained descriptors. The
address skipping starts from the end of current descriptor to the start of next
descriptor. When DSL value equals zero, then the descriptor table is taken as
contiguous by the DMA, in Ring mode.
0
R/W
7
ATDS
Alternate descriptor size
When set, the alternate descriptor (see
) size is increased to 32 bytes
(8 DWORDS). This is required when the Advanced Time-Stamp feature or Full IPC
Offload Engine is enabled in the receiver.
When reset, the descriptor size reverts back to 4 DWORDs (16 bytes).
0
R/W