6–28
Chapter 6: IP Core Interfaces
Clock Signals
Arria V GZ Hard IP for PCI Express
November 2012
Altera Corporation
Clock Signals
describes the clock signals that comprise the clock interface.
Refer to
for a complete description of the clock interface.
Reset Signals and Status Signals
describes the reset signals. Refer to
information about the reset sequence and a block diagram of the reset logic.
Table 6–6. Clock Signals Hard IP Implementation
Signal
I/O
Description
refclk
I
Reference clock for the Arria V GZ Hard IP for PCI Express. It must have the frequency
specified under the
System Settings
heading in the parameter editor.
pld_clk
I
Clocks the Application Layer. You must drive this clock from
coreclkout_hip
.
coreclkout_hip
O
This is a fixed frequency clock used by the Data Link and Transaction Layers. To meet PCI
Express link bandwidth constraints, this clock has minimum frequency requirements as listed
in
.
Note to
(1)
illustrates these clock signals.
Table 6–7. Reset and Link Training Signals (Part 1 of 3)
Signal
I/O
Description
npor
I
Active low reset signal. In the Altera hardware example designs,
npor
is the
OR
of
pin_perst
and
local_rstn
coming from the software Application Layer. If you do not
drive a soft reset signal from the Application Layer, this signal must be derived from
pin_perst
. You cannot disable this signal. Asynchronous. Resets the entire Arria V GZ Hard
IP for PCI Express IP Core and transceiver.
In systems that use the hard reset controller, this signal is
edge
,
not level
sensitive;
consequently, you cannot use a low value on this signal to hold custom logic in reset. For
more information about the hard and soft reset controllers, refer to
reset_status
O
Active high reset status signal. When asserted, this signal indicates that the Hard IP clock is
in reset. The
reset_status
signal is synchronous to the
pld_clk
clock and is deasserted
only when the
npor
is deasserted and the Hard IP for PCI Express is not in reset
(
reset_status_hip
= 0). You should use
reset_status
to drive the reset of your
application.