Altera IP Compiler for PCI Express - Manual (Page 139)

Chapter 5: IP Core Interfaces 5–53
Physical Layer Interface Signals
August 2014 Altera Corporation IP Compiler for PCI Express User Guide
Physical Layer Interface Signals
This section describes the global PHY support signals which are only present in
variations that target an Arria II GX, Arria II GZ, Cyclone IV GX, or Stratix IV GX
device and use an integrated PHY. When selecting an integrated PHY, the parameter
editor generates a SERDES variation file, _serdes. or vhd >, in addition
to the IP core variation file, .<v or vhd>.
Transceiver Control Signals
Table 5–28 describes the transceiver support signals.
Table 5–28. Transceiver Control Signals (Part 1 of 2)
Signal Name in
Qsys (1)
I/O Description
cal_blk_clk
/cal_blk_clk_clk
I
The cal_blk_clk input signal is connected to the transceiver calibration block
clock (cal_blk_clk) input. All instances of transceivers in the same device
must have their cal_blk_clk inputs connected to the same signal because
there is only one calibration block per device. This input should be connected to a
clock operating as recommended by the
Stratix II GX Transceiver User Guide , the
Stratix IV Transceiver Architecture , or the Arria II GX Transceiver Architecture
chapter in volume 2 of the Arria II GX Device Handbook. Connection information
is also provided in
Figure 7–4 on page 7–5 , Figure 7–6 on page 7–9 , and
Figure 7–7 on page 7–10 .
gxb_powerdown/
pipe_ext_gxb_powerdown
I
The gxb_powerdown signal connects to the transceiver calibration block
gxb_powerdown input. This input should be connected as recommended by the
Stratix II GX Device Handbook or volume 2 of the Stratix IV Device Handbook.
When the calibration clock is not used, this input must be tied to ground.
reconfig_fromgxb[16:0]
(Stratix IV GX ×1 and ×4)
reconfig_fromgxb[33:0]
(Stratix IV GX ×8)
reconfig_togxb[3:0]
(Stratix IV GX)
reconfig_clk
(Arria II GX, Arria II GZ,
Cyclone IV GX)/
reconfig_gxbclk_clk
O
O
I
I
I
These are the transceiver dynamic reconfiguration signals. These signals may be
used for cases in which the IP Compiler for PCI Express instance shares a
transceiver quad with another protocol that supports dynamic reconfiguration.
They may also be used in cases in which the transceiver analog controls (V
OD
,
pre-emphasis, and manual equalization) must be modified to compensate for
extended PCI Express interconnects such as cables. In these cases, these signals
must be connected as described in the
Stratix II GX Device Handbook , otherwise,
when unused, the reconfig_clk signal should be tied low, reconfig_togxb
should be tied to b'010, and reconfig_fromgxb should be left open.
For Arria II GX and Stratix IV GX devices, dynamic reconfiguration is required for
IP Compiler for PCI Express designs to compensate for variations due to
process, voltage and temperature. You must connect the ALTGX_RECONFIG
instance to the ALTGX instances with receiver channels in your design using
these signals. The maximum frequency of reconfig_clk is 50 MHz. For more
information about instantiating the ALTGX_RECONFIG megafunction in your
design refer to
“Transceiver Offset Cancellation” on page 13–9 .
fixedclk_serdes I
A 125 MHz free running clock that you must provide that serves as input to the
fixed clock of the transceiver. fixedclk_serdes and the 50 MHz
reconfig_clk
must be free running and not derived from refclk. This signal
is used in the hard IP implementation for Arria II GX, Arria II GZ, Cyclone IV GX,
HardCopy IV GX, and Stratix IV GX devices.