3–98
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Channel and Clock Multiplier Unit (CMU) PLL Reconfiguration
Logical TX PLL
In the channel reconfiguration feature (
“Channel Reconfiguration” on
page 3–30
), you cannot reconfigure the TX PLLs dynamically. It was not
necessary to know which of the two TX PLLs was configured for the
specified data rate. You were required to set only the
logical reference
index
option in the ALT2GXB MegaWizard to select the output clocks of
the main and alternate TXPLLs and the
clock mux
in the RX PLL side
(refer to
Figure 3–40
for the location of these multiplexers).
When you use the
Channel and CMU PLL Reconfiguration
option, you
can dynamically reconfigure the channel and the TX PLL. Therefore, to
reconfigure the TX PLL during run time, you need the flexibility to select
the TX PLL. When you enable this option, the ALT2GXB MegaWizard
provides a logical identification for the main and alternate TXPLLs. This
identification is referred to as the “logical tx pll” value. This value
provides a logical identification to the TX PLL that is associated with a
transceiver channel, without requiring the knowledge of its physical
location.
In the ALT2GXB MegaWizard, when you provide the main TXPLL with a
logical tx pll value, for example
0
, the alternate TXPLL automatically
takes the complement value
1
. The logical tx pll value for the main TXPLL
is stored along with the other transceiver channel information in the
generated MIF. You can reuse the MIF generated for one TX PLL to
reconfigure the other TX PLL in the same or in other transceiver blocks.
The dynamic reconfig controller provides you an optional
logical_tx_pll_sel
port for this purpose. The method to use this
port and reconfigure a TX PLL is explained in
“Logical TX PLL” on
page 3–98
.
Using the Channel and CMU PLL Reconfiguration Feature
The channel and CMU PLL reconfiguration feature is divided into three
categories based on the functionality:
■
Channel and TX PLL reconfiguration
■
TX PLL reconfiguration
■
Channel reconfiguration with TX PLL select
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