Altera Corporation
2–219
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
The
tx_digitalreset
and
rx_analogreset
signals can be
deasserted after the
pll_locked
signal goes high. The reset controller
should deassert the
rx_digitalreset
when the
rx_pll_locked
signal goes high.
The parallel data sent to the PLD logic array in the receive side may not
be valid until 4 us (T2) after
rx_freqlocked
goes high.
Normal Operation Phase
During normal operations, the receive data is valid and the
rx_freqlocked
signal is high. In this situation, when
rx_freqlocked
is deasserted, (marker 8 in
Figure 2–161
), the reset controller should wait
for the
rx_freqlocked
to go high again and assert
rx_digitalreset
(marker 10 in
Figure 2–161
) for two parallel receive clock cycles.
The data from the gigabit transceiver block is not valid between the time
when
rx_freqlocked
goes low until
rx_digitalreset
is
deasserted. The PLD logic should ignore the data during this time period
(the time period between markers 8 and 11 in
Figure 2–161
).
1
Minimum T1 period is 100 ns. Minimum T2 and T3 periods are
4 us. T4 indicates two parallel receive clock cycles.
Rate Matcher FIFO Buffer Overflow and Underflow Condition
During the normal operating phase, the reset controller monitors the
overflow and underflow status of the rate matcher FIFO buffer. If there is
overflow and underflow on the rate matcher FIFO buffer, the reset
controller asserts
rx_digitalreset
for two receive parallel clock
cycles. You can monitor the rate matcher FIFO buffer status through the
pipestatus[2:0]
signal from the PIPE interface. This condition is
shown in
Figure 2–162
.
Figure 2–162. PIPE Mode Reset During Rate Matcher FIFO Buffer Overflow and Underflow Condition
Notes to
Figure 2–162
:
(1)
Pipestatus = 101 represents elastic overflow.
(2)
Pipestatus = 110 represents elastic overflow.
tx_digitalreset
rx_analogreset
rx_digitalreset
rx_freqlocked
pipestatus
T4
T4
1
0
1
0
1
0
1
0
000
101
000
110
000