NXP Semiconductors LPC24XX UM10237 - Manual (Page 230)

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User manual Rev. 04 — 26 August 2009 230 of 792
NXP Semiconductors
UM10237
Chapter 11: LPC24XX Ethernet
The receive descriptor base address is a byte address aligned to a word boundary i.e.
LSB 1:0 are fixed to ’00’. The register contains the lowest address in the array of
descriptors.
7.2.4 Receive Status Base Address Register (RxStatus - 0xFFE0 010C)
The receive descriptor base address is a byte address aligned to a word boundary i.e.
LSB 1:0 are fixed to ’00’. The register contains the lowest address in the array of
descriptors.
The receive status base address is a byte address aligned to a double word boundary i.e.
LSB 2:0 are fixed to ’000’.
7.2.5 Receive Number of Descriptors Register (RxDescriptor - 0xFFE0 0110)
The Receive Number of Descriptors register (RxDescriptorNumber) has an address of
0xFFE0 0110. Its bit definition is shown in
Table 11–210 .
The receive number of descriptors register defines the number of descriptors in the
descriptor array for which RxDescriptor is the base address. The number of descriptors
should match the number of statuses. The register uses minus one encoding i.e. if the
array has 8 elements, the value in the register should be 7.
7.2.6 Receive Produce Index Register (RxProduceIndex - 0xFFE0 0114)
The Receive Produce Index register (RxProduceIndex) is a Read Only register with an
address of 0xFFE0 0114. Its bit definition is shown in
Table 11–211 .
Table 209. receive Status Base Address register (RxStatus - address 0xFFE0 010C) bit
description
Bit Symbol Function Reset
value
2:0 - Fixed to ’000’ -
31:3 RxStatus MSBs of receive status base address. 0x0
Table 210. Receive Number of Descriptors register (RxDescriptor - address 0xFFE0 0110) bit
description
Bit Symbol Function Reset
value
15:0 RxDescriptorNumber Number of descriptors in the descriptor array for which
RxDescriptor is the base address. The number of
descriptors is minus one encoded. 0x0
31:16 - Unused 0x0
Table 211. Receive Produce Index register (RxProduceIndex - address 0xFFE0 0114) bit
description
Bit Symbol Function Reset
value
15:0 RxProduceIndex Index of the descriptor that is going to be filled next by the
receive datapath.
0x0
31:16 - Unused 0x0