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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
133 of 808
NXP Semiconductors
UM10360
Chapter 10: LPC17xx Ethernet
TxProduceIndex equals TxConsumeIndex - 1 the descriptor array is full and software
should stop producing new descriptors until hardware has transmitted some frames and
updated the TxConsumeIndex.
12.12 Transmit Consume Index Register (TxConsumeIndex - 0x5000 012C)
The Transmit Consume Index register (TxConsumeIndex) is a Read Only register with an
address of 0x5000 012C. Its bit definition is shown in
The transmit consume index register defines the descriptor that is going to be transmitted
next by the hardware transmit process. After a frame has been transmitted hardware
increments the index, wrapping the value to 0 once the value of TxDescriptorNumber has
been reached. If the TxConsumeIndex equals TxProduceIndex the descriptor array is
empty and the transmit channel will stop transmitting until software produces new
descriptors.
12.13 Transmit Status Vector 0 Register (TSV0 - 0x5000 0158)
The Transmit Status Vector 0 register (TSV0) is a Read Only register with an address of
0x5000 0158. The transmit status vector registers store the most recent transmit status
returned by the MAC. Since the status vector consists of more than 4 bytes, status is
distributed over two registers TSV0 and TSV1. These registers are provided for debug
purposes, because the communication between driver software and the Ethernet block
takes place primarily through the frame descriptors. The status register contents are valid
as long as the internal status of the MAC is valid and should typically only be read when
the transmit and receive processes are halted.
lists the bit definitions of the TSV0 register.
Table 137. Transmit Consume Index register (TxConsumeIndex - address 0x5000 012C) bit
description
Bit
Symbol
Function
Reset
value
15:0
TxConsumeIndex
Index of the descriptor that is going to be transmitted next by
the transmit datapath.
0x0
31:16
-
Unused
0x0
Table 138. Transmit Status Vector 0 register (TSV0 - address 0x5000 0158) bit description
Bit
Symbol
Function
Reset
value
0
CRC error
The attached CRC in the packet did not match the
internally generated CRC.
0
1
Length check error
Indicates the frame length field does not match the actual
number of data items and is not a type field.
0
2
Length out of range
Indicates that frame type/length field was larger than
1500 bytes.
0
3
Done
Transmission of packet was completed.
0
4
Multicast
Packet’s destination was a multicast address.
0
5
Broadcast
Packet’s destination was a broadcast address.
0
6
Packet Defer
Packet was deferred for at least one attempt, but less than
an excessive defer.
0