PNX1500E NXP Semiconductors, PNX1500E Datasheet - Page 709

• Manufacturer Part Number: PNX1500E
• Manufacturer: NXP Semiconductors

Specifications of PNX1500E

• Lead Free Status / Rohs Status: Not Compliant

NXP Semiconductors
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PNX15XX_PNX952X_SER_N_4
Product data sheet
5.4.5 Update ConsumeIndex
5.4.6 Write Transmission Status
5.4.7 Transmission Error Handling
them out as one Ethernet frame on the Ethernet connection. When the Tx DMA
manager finds a descriptor with the Last bit in the Control field set to 1, this indicates
the last fragment of the frame, and thus the end of the Ethernet frame.
Each time the Tx(Rt) DMA manager commits a status word to memory, it completes
the transmission of a descriptor. It increments the Tx(Rt)ConsumeIndex (taking wrap
around into account) to hand the descriptor back to the device driver software.
Software can re-use the descriptor for new transmissions after the hardware has
handed it back.
The device driver software can keep track of the progress of the DMA manager by
reading the Tx(Rt)ConsumeIndex register to see how far along the transmit process
is. When the Tx descriptor FIFOs get emptied completely, the TxConsumeIndex and
TxRTConsumeIndex retain their last value.
After the packet has been transmitted over the (R)MII bus and the status has been
committed to memory, the StatusInfo and StatusTimeStamp words of the packet
descriptor are updated by the DMA manager.
If the descriptor is for the last fragment of a packet (or for the whole packet if there are
no fragments), then error flags are set (on failure) or cleared (on success) depending
on the success or failure of the packet transmission. Error flags are Error,
LateCollision, ExcessiveCollision, Underrun, ExcessiveDefer, and Defer. The
CollisionCount field is set to the number of collisions the packet incurred, up to the
Retransmission Maximum programmed in the Collision Window/Retry register. The
current time-stamp time is written to the StatusTimeStamp field.
Statuses for all but the last fragment in the packet will be written as soon as the data
in the packet has been accepted by the Tx(Rt) DMA manager. Even if the descriptor
is for a packet fragment other than the last fragment, the error flags and time-stamp
are returned. If the MII Interface detects a transmission error during transmission of a
(multi-fragment) packet, the rest of the transmit data and all remaining fragments of
the packet are still read. After an error, the remaining transmit data is discarded by
the MII Interface. In case of errors during transmission of a multi fragment packet, the
error statuses will be repeated until the last fragment of the packet. Statuses for all
but the last fragment in the packet will be written as soon as the data in the packet
has been accepted by the Tx(Rt) DMA manager. The status for the last fragment in
the packet will only be written after the transmission has completed on the Ethernet
connection.
The status of the last packet transmission can also be inspected by reading the TSV0
and TSV1 registers. These registers do not report statuses on a fragment basis and
do not store information of previously sent packets.
When an error occurs during the transmit process, the Tx(Rt) DMA manager will
report the error via the transmission Status written in the Status FIFO and the
IntStatus interrupt status register.
Rev. 4.0 — 03 December 2007
Chapter 23: LAN100 — Ethernet Media Access Controller
PNX15xx/952x Series
© NXP B.V. 2007. All rights reserved.
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