3–132
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Channel and Clock Multiplier Unit (CMU) PLL Reconfiguration
In this example, the three channels are reconfigured in a transceiver bank.
This means that two TX PLLs are shared between three channels.
Therefore, if you use a main and alternate TXPLL for each channel, you
can reconfigure the channel to any two of the four protocols by switching
between the two TX PLLs.
Figure 3–65
shows the TX PLL connections of the TX side. (To simplify the
illustration, only the TX side is shown). The figure shows that the default
configurations of CH0, CH1, and CH2 are FC-4G, FC-2G, and GIGE,
respectively.
Figure 3–65. Logical TX PLL Connections with the Transceiver Channel
How Many MIFs Do I Require?
You will need four MIFs for this design. You can generate the MIFs for one
TX PLL and use the
logical_tx_pll_sel
in the reconfig controller to
write the MIF contents into the second TX PLL. Assume that the TX PLL
configured for FC- 4G data rate is assigned a logical tx pll value of
0
. This
means that the other TX PLL configured for GIGE and SONET/SDH
pll_inclk_rx_cruclk[2]
pll_inclk_rx_cruclk[1]
pll_inclk_rx_cruclk[0]
77.76 MHz
125 MHz
106.25 MHz
clock
MUX
clock
MUX
4.25 Gbps/
1.25 Gbps/
2.48 Gbps
Logical TXPLL0
4.25 Gbps/
1.25 Gbps/
2.48 Gbps
Logical TXPLL1
TX Side of CH0 - Default
Configuration FC 4
TX Side of CH1 - Default
Configuration FC 2
Logical
TX PLL
Select
LOCAL
DIVIDER
d analog logic
d analog logic
LOCAL
DIVIDER
Logical
TX PLL
Select
TX Side of CH2 - Default
Configuration GIGE
d analog logic
LOCAL
DIVIDER
Logical
TX PLL
Select
Alternate TXPLL set during ALT2GXB
megawizard instantiation
Main TXPLL set during ALT2GXB
megawizard instantiation