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IXF1104 4-Port Gigabit Ethernet Media Access Controller
Datasheet 92
Document Number: 278757
Revision Number: 009
Revision Date: 27-Oct-2005
The IXF1104 MAC provides the following three types of TPA signals:
• Dedicated per port Direct Transmit Packet Available (DTPA)
• Selected-PHY Transmit Packet Available (STPA), which is based on the current in-band port
address in MPHY mode.
• Polled-PHY Transmit packet Available (PTPA), which provides FIFO information on the port
selected by the TADR[1:0] signals.
The following three TPA signals (DTPA_0:3, STPA, and PTPA) provide flow control based on the
programmable TX FIFO High and Low watermarks. Refer to Table 132 “TX FIFO High
Watermark Ports 0 - 3 ($0x600 – 0x603)” on page 203 and Table 133 “TX FIFO Low Watermark
Register Ports 0 - 3 ($0x60A – 0x60D)” on page 204 for more information.
DTPA_0:3:
A direct status indication for the TX FIFOs of ports [0:3]. When DTPA is High, it indicates the
amount of data in the TX FIFO is below the TX FIFO High watermark. When the High watermark
is crossed, DTPA transitions Low to indicate the TX FIFO is almost full. It stays low until the
amount data in the TX FIFO goes back below the TX FIFO Low watermark. At this point, DTPA
transitions High to indicate the programmed number of bytes are now available for data transfers.
DTPA_0:3 is updated on the rising edge of the TFCLK.
STPA:
STPA provides TX FIFO status for the currently selected port in MPHY mode. When High, STPA
indicates that the amount of data in the TX FIFO for the port selected, specified by the latest in-
band address, is below the TX FIFO High watermark. When the High watermark is crossed, STPA
transitions Low to indicate the TX FIFO is almost full. It stays Low until the amount of data in the
TX FIFO goes back below the TX FIFO Low watermark. At this point, STPA transitions High to
indicate the programmed number of bytes are now available for data transfers.
The port reported by STPA is updated on the rising edge of TFCLK after TSX is sampled as
asserted. STPA is updated on the rising edge of TFCLK.
Note: STPA is only used when the IXF1104 MAC is configured for MPHY mode of operation.
PTPA:
PTPA provides status of the TX FIFO based on the port selected by the TADR[1:0] address bus.
When High, PTPA indicates that the amount of data in the TX FIFO for the port selected is below
the TX FIFO High watermark. When the High watermark is crossed, PTPA transitions Low to
indicate the TX FIFO is almost full. It stays Low until the amount of data in the TX FIFO goes
back below the TX FIFO Low watermark. PTPA then transitions High to indicate the programmed
number of bytes are now available for data transfers.
The port reported by PTPA is updated on the rising edge of TFCLK after the TADR{1:0] port
address is sampled.
PTPA is updated on the rising edge of TFCLK.