NXP Semiconductors LPC1768 - Receive Descriptor Base Address Register (Rxdescriptor - 0 X5000 0108); Receive Status Base Address Register (Rxstatus - 0 X5000 010 C); Receive Number of Descriptors Register (Rxdescriptor - 0 X5000 0110)

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User manual Rev. 3 — 19 December 2013 160 of 841
NXP Semiconductors
UM10360
Chapter 10: LPC176x/5x Ethernet
• It is enabled and the Rx/TxEnable bit is set in the Command register or it just got
disabled while still transmitting or receiving a frame.
• Also, for the transmit channel, the transmit queue is not empty
i.e. ProduceIndex != ConsumeIndex.
• Also, for the receive channel, the receive queue is not full
i.e. ProduceIndex != ConsumeIndex - 1.
The status transitions from active to inactive if the channel is disabled by a software reset
of the Rx/TxEnable bit in the Command register and the channel has committed the status
and data of the current frame to memory. The status also transitions to inactive if the
transmit queue is empty or if the receive queue is full and status and data have been
committed to memory.
10.12.3 Receive Descriptor Base Address Register (RxDescriptor -
0x5000 0108)
The Receive Descriptor base address register (RxDescriptor) has an address of
0x5000 0108. Its bit definition is shown in Table 150
.
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.
10.12.4 Receive Status Base Address Register (RxStatus - 0x5000 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”.
10.12.5 Receive Number of Descriptors Register (RxDescriptor - 0x5000 0110)
The Receive Number of Descriptors register (RxDescriptorNumber) has an address of
0x5000 0110. Its bit definition is shown in Table 152
.
Table 150. Receive Descriptor Base Address register (RxDescriptor - address 0x5000 0108)
bit description
Bit Symbol Function Reset
value
1:0 - Fixed to ’00’ -
31:2 RxDescriptor MSBs of receive descriptor base address. 0x0
Table 151. receive Status Base Address register (RxStatus - address 0x5000 010C) bit
description
Bit Symbol Function Reset
value
2:0 - Fixed to ’000’ -
31:3 RxStatus MSBs of receive status base address. 0x0