NXP Semiconductors LPC24XX UM10237 - Manual (Page 233)

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User manual Rev. 04 — 26 August 2009 233 of 792
NXP Semiconductors
UM10237
Chapter 11: LPC24XX Ethernet
7.2.12 Transmit Consume Index Register (TxConsumeIndex - 0xFFE0 012C)
The Transmit Consume Index register (TxConsumeIndex) is a Read Only register with an
address of 0xFFE0 012C. Its bit definition is shown in
Table 11–217 .
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.
7.2.13 Transmit Status Vector 0 Register (TSV0 - 0xFFE0 0158)
The Transmit Status Vector 0 register (TSV0) is a Read Only register with an address of
0xFFE0 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.
Table 11–218 lists the bit definitions of the TSV0 register.
Table 217. Transmit Consume Index register (TxConsumeIndex - address 0xFFE0 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 218. Transmit Status Vector 0 register (TSV0 - address 0xFFE0 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 [1] 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
7 Excessive Defer Packet was deferred in excess of 6071 nibble times in
100 Mbps or 24287 bit times in 10 Mbps mode. 0
8 Excessive Collision Packet was aborted due to exceeding of maximum allowed
number of collisions. 0
9 Late Collision Collision occurred beyond collision window, 512 bit times. 0