UM10503
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User manual
Rev. 1.3 — 6 July 2012
707 of 1269
NXP Semiconductors
UM10503
Chapter 26: LPC43xx Ethernet
26.6.29 DMA Receive poll demand register
The Receive Poll Demand register enables the receive DMA to check for new descriptors.
This command is given to wake up the RxDMA from SUSPEND state. The RxDMA can go
into SUSPEND state only due to the unavailability of descriptors owned by it.
26.6.30 DMA Receive descriptor list address register
The Receive Descriptor List Address register points to the start of the Receive Descriptor
List. The descriptor lists reside in the host’s physical memory space and must be
Word-aligned . The DMA internally converts it to bus width aligned address by making the
corresponding LS bits low. Writing to this register is permitted only when reception is
stopped. When stopped, this register must be written to before the receive Start command
is given.
26.6.31 DMA Transmit descriptor list address register
The Transmit Descriptor List Address register points to the start of the Transmit Descriptor
List. The descriptor lists reside in the host’s physical memory space and must be
Word-aligned . The DMA internally converts it to bus width aligned address by making the
corresponding LSB to low. Writing to this register is permitted only when transmission has
stopped. When stopped, this register can be written before the transmission Start
command is given.
Table 563. DMA Receive poll demand register (DMA_REC_POLL_DEMAND, address 0x4001
1008) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
RPD
Receive poll demand
This register field can be read by the application, and when
a write operation is performed with any data value, an event
is triggered.
When these bits are written with any value, the DMA reads
the current descriptor pointed to by the Current Host
Receive Descriptor register (
). If that
descriptor is not available (owned by Host), reception
returns to the Suspended state and bit 7 in the DMA_STAT
Register is not asserted. If the descriptor is available, the
Receive DMA returns to active state.
0
R/W
Table 564. DMA Receive descriptor list address register (DMA_REC_DES_ADDR, address
0x4001 100C) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
SRL
Start of receive list
This field contains the base address of the First Descriptor
in the Receive Descriptor list. The LSB bit 1 will be ignored
and taken as all-zero by the DMA internally. Hence these
LSB bits are Read Only.
0
R/W