3–36
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Channel and PMA Controls Reconfiguration
ALT2GXB Configuration Related to Channel Reconfiguration
You must setup the following two system design aspects in a ALT2GXB
MegaWizard instance:
■
Transceiver and Core Clocking
■
PLD Data Path Interface
Transceiver and Core Clocking
You must set up the core clocking and transceiver clocking options as part
of channel reconfiguration for functional mode switchover or data rate
transition. Transceiver clocking covers all the clock options you need to
set up:
■
Two TX PLLs for data rates and functional modes
■
Input reference clocks for transmit and receive
■
Internal clock MUX reference index setups
Core clocking covers the PLD interface clocking. PLD interface clocking
is related to the parallel transmit and receive clocks (
tx_clkout
and
rx_clkout
). These clocks are used to parallel transmit data into and
parallel receive data out of the transceiver. Core clocking is needed in any
channel reconfiguration. Core clock assignments (clock grouping
assignment and 0 PPM assignments) will override the core clocking set in
the ALT2GXB instance. The details related to transceiver and core
clocking are discussed in the following section. Transceiver and core
clocking are classified as:
■
Data rate switch using local clock block dividers
■
Data rate switch based on clock frequencies of two PLLs in the
transceiver block
Data Rate Switch Using Local Clock Block Dividers
If you intend to switch the data rate in multiples of 1, 2, and 4 of the base
data rate, use the local clock dividers. Local clock dividers further divide
the TX PLL base rate and are present in transmit and receive block of
every transceiver channel (refer to
Figure 3–15
).
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