Altera Triple Speed Ethernet MegaCore Function - Manual (Page 64)

When a collision happens, the collision detection state machine drives the
mii_rx_col
and
led_col
signals
to 1. You can use the
led_col
signal as a visual check using a board LED.
Transmit and Receive Latencies
Altera uses the following definitions for the transmit and receive latencies for the PCS function with an
embedded PMA:
• Transmit latency is the time the PCS function takes to transmit the first bit on the PMA-PCS interface
after the bit was first available on the MAC side interface (MII/GMII).
• Receive latency is the time the PCS function takes to present the first bit on the MAC side interface
(MII/GMII) after the bit was received on the PMA-PCS interface.
Table 4-11: PCS Transmit and Receive Latency
These latencies are derived from a simulation. For transceiver latency, refer to the transceiver handbook of the
respective device family.
Latency (ns)
PCS Configuration
Receive Transmit
PCS with GX transceivers
2489 3368 10-Mbps SGMII
335 488 100-Mbps SGMII
135 184 1000-Mbps SGMII
40 24 1000BASE-X
PCS with LVDS Soft-CDR I/O
2344 3600 10-Mbps SGMII
344 440 100-Mbps SGMII
184 192 1000-Mbps SGMII
104 40 1000BASE-X
SGMII Converter
You can enable the SGMII converter by setting the SGMII_ENA bit in the if_mode register to 1. When enabled
and the
USE_SGMII_AN
bit in the
if_mode
register is set to 1, the SGMII converter is automatically configured
with the capabilities advertised by the PHY. Otherwise, Altera recommends that you configure the SGMII
converter with the
SGMII_SPEED
bits in the
if_mode
register.
In 1000BASE-X mode, the PCS function always operates in gigabit mode and data duplication is disabled.
Transmit
In gigabit mode, the PCS and MAC functions must operate at the same rate. The transmit converter transmits
each byte from the MAC function once to the PCS function.
In 100-Mbps mode, the transmit converter replicates each byte received by the PCS function 10 times. In
10 Mbps, the transmit converter replicates each byte transmitted from the MAC function to the PCS function
100 times.
Functional Description Altera Corporation
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Transmit and Receive Latencies 4-28
2014.06.30