SerialLite II IP Core User Guide

ID 683179
Date 7/13/2021
Public
Document Table of Contents

3.3.7. Initialization and Restart

Before the SerialLite II link can operate, the IP core must properly reset the GX transceiver. The SerialLite II IP core must then be initialized and trained.
Note: This initialization and restart sequence is only applicable to Arria II GX and Stratix IV devices. For the later devices, refer to the respective Device Handbooks.

The SerialLite II training sequence can generally bring the link up in a few hundred microseconds; the actual amount of time required varies according to PLL lock times, the number of lanes, the per-lane deskew, and other variation-specific factors. The reset of the GX transceiver is controlled by the mreset_n and gxb_powerdown signals. The minimum pulse width is determined by characterization. Currently, a 2 ms pulse width is sufficient for the gxb_powerdown input, and three cycles for the mreset_n signal. For simulation, a reset duration of several clock cycles (for example, 10) is sufficient.

A link only restarts on its own if a link error occurs during normal operation. A hardware reset using the mreset_n signal also brings down the link when the reset is asserted low and reestablishes the link when the reset is released. When one end of the link is brought down by either of these means, it brings the other end down by sending training sequences to the other end of the link. The other end of the link restarts after it sees eight successive training sequences.

Figure 31. InitializationThis figure shows what happens when you initialize the SerialLite II IP core.


When the reset_n input signal is asserted, the transceiver and the IP core start to reset and initialize the IP core. When the corresponding signals, stat_tc_pll_locked, stat_rr_freqlock, and the stat_tc_rst_done signal go high, a set of training sequence are transmitted across the link to align the characters and lanes. When everything is synchronized, the link is established and ready to be used, stat_rr_link = 1.