Altera Stratix GX Transceiver - Manual (Page 315)

Altera Corporation C–5
January 2005 Stratix GX Transceiver User Guide
■ Error: XGMII
GXB_RX:GXB_RX_a|CUSTOM_RX:CUSTOM_RX_inst|altgxb:altg
xb_component|xgm_machine[0] exists in a Quad that has no GXB
Transmitters and has GXB Transmitter PLL
GXB_RX:GXB_RX_a|CUSTOM_RX:CUSTOM_RX_inst|altgxb:altg
xb_component|pll[0], but all the RXANALOGRESET signals are
connected. This is not allowed.
f
Refer to recommendation n in the section “Recommendations” on
page C–5 if you have an existing design (including the board) and wish
to keep the design.
Recommendations
The reset sequences described here are only recommendations. These
recommendations are to guard against potential initialization issues.
However, the transmitter PLLs within the transceivers are robust and
should track the reference clock during a loss of lock conditions without
requiring a reset. This reset signal must be used only if the PLLs fall into
an unrecoverable state. During lab testing at the factory, the Stratix GX
device did not require that the PLLs be reset. The PLLs have a wide pull
in range and were able to relock to their respective reference clocks.
There might be situations where the read and write pointers in the phase
compensation FIFO overlap. This will manifest as incorrect transmit data
and in some cases, receive data. A digital reset should correct this error.
Here are the reset and clocking recommendations:
■ Do not run the reset controller off the clock from the REFCLKB pin.
This might result in the signals to the GXB being deasserted
asynchronously (with respect to the clocks from the GXB). However,
a serial link usually goes through an initialization phase. Hence, any
concerns of meta-stability issues may not be critical as the logic has
enough time to recover during initialization.
To issue a pll_areset or pllenable or rxanalogreset (receive
only) with configurations
1 or 2 using the Quartus II software
version 4.0, use the following INI variable:
asm_skip_gxb_clock_fanout_restriction=on
For the Quartus II software version 4.0 SP1 (for configurations 1 , 2 ,
and 3 ), the setting in the Quartus II Settings File (.qsf) must be
set_global_assignment -name
STRATIXGX_ALLOW_CLOCK_FANOUT_WITH_ANALOG_RESET ON