Altera Cyclone IV Device Handbook page 390

2–16
This solution may violate some of the protocol specific requirements. In such case,
you can use Manual CDR lock option.
For Manual CDR lock mode, rx_freqlocked signal is not available. Upon
■
detection of a dead link, take the following steps:
a. Switch to LTR mode.
b. Assert rx_digitalreset.
c. Wait for rx_pll_locked to go high.
d. When you detect incoming data on the receive pins, switch to LTD mode.
e. Wait for a duration of t
f. De-assert rx_digitalreset.
Cyclone IV Device Handbook,
Volume 2
LTD_Manual
after the rx_locktodata signal is asserted in manual mode.
Chapter 2: Cyclone IV Reset Control and Power Down
, which is the time taken to recover valid data
September 2014 Altera Corporation
Transceiver Reset Sequences