Altera Corporation
3–85
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Dynamic Reconfiguration
1
Use the
rate_switch_ctrl
signal only for dividing the data
rate of the transmit side. To divide the data rate for both the
transmit and receive sides, a MIF-based approach is required.
This example uses a Basic mode with 8B/10B enabled running at 4 Gbps
data rate. You can configure the mode dynamically between 4.25 Gbps,
2.25 Gbps, and 1.125 Gbps.
The description for this design example is divided into the following
sections:
■
Section I—Create the ALT2GXB Instantiation for the Transceiver
Channel
■
Section II—Create the ALT2GXB_RECONFIG Instantiation
■
Section III—Create the Top-Level Design
Section I—Create the ALT2GXB Instantiation for the Transceiver
Channel:
1.
Create a
Basic mode
by setting the operation mode to
Transmit and
Receive
.
2.
Select
double width
mode. This is required since the highest data
rate in this example is 4.25 Gbps (
Single width
can be selected only
up to 3.125 Gbps). Set the channel width to
32
. The lowest PLD
frequency allowed in the Quartus II software is 25 MHz. Therefore,
the transceiver runs at 1.125 Gbps with a 32-bit PLD interface. The
PLD clock frequency in this case is 26.5 MHz (1125/40 = 26.5).
3.
Set the input frequency to
106.25 MHz
.
4.
In the
Reconfig
tab, check the
Channel internals
option. This is
required to enable the ALT2GXB_RECONFIG instance to modify
the channel local divider values dynamically. The alternate
reference clock is not required since one clock source is used. Also,
the data rates can be derived from the 106.25 MHz clock.
5.
Complete the ALT2GXB MegaWizard instantiation.
Section II—Create the ALT2GXB_RECONFIG Instantiation:
1.
Instantiate the ALT2GXB_RECONFIG megafunction as described in
“Example 1—Configuring a Transceiver Channel Between GIGE
Mode and SONET/SDH OC48 Mode” on page 3–72
.
2.
Select the
Modify the data rate using the local divider
option in the
Reconfiguration Settings
tab. This creates the
rate_switch_ctrl
and
rate_switch_ctrl_out
signals.