Altera Corporation
3–37
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Dynamic Reconfiguration
Figure 3–15. Transmit Local Clock Divider Block
Transmit local clock dividers are placed after the CMU PLLs and thus the
TX PLLs are not affected during a data rate switch using local clock
dividers.
Receive local clock dividers are placed before the RX PLL (CDR). Thus the
RX PLL is affected every time the data rate switch using local clock
dividers occurs. The Quartus II software data rate division factor chooses
a combination of local clock dividers and feedback dividers present in the
CDR that yields the best performance (refer to
Figure 3–16
).
Figure 3–16. Receive Local Clock Divider Block
To configure the local divider using the same TX PLL base setting, use the
following steps:
1.
Set the base setting on the CMU PLL (use the fastest data rate that is
intended to be reconfigured to).
2.
Set the local clock divider setting (use the effective data rate for that
configuration).
3.
Enable either the
Channel Internals
or
Channel Interface
option
(refer to
“Channel Internals” on page 3–53
and
“Channel Interface”
on page 3–53
for more information).
/4,/5,
/8,/10
high speed clock
to TX
slow speed clock
to TX
TX Local Clk Div Block
high speed clock
from TXPLL0
high speed clock
from TXPLL1
/1,2,4
/n
slow speed clock
to RX
RX Local Clk Div Block
/1,2,4
/n
CDR/
Clock
Dividers
rx_cru_clk
rx_cru_clk_alt
Содержание Stratix II GX
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