ep1sgx25d Altera Corporation, ep1sgx25d Datasheet - Page 62

• Manufacturer Part Number: ep1sgx25d
• Description: Stratix Gx Device Family Data Sheet
• Manufacturer: Altera Corporation

Introduction
3–12
Stratix GX Device Handbook, Volume 1
The actual lock time for different data patterns varies depending on the
data’s transition density (how often the data switches between 1 and 0)
and jitter characteristic. The DPA circuitry is designed to lock onto any
data pattern with sufficient transition density, so the circuitry works with
current and future protocols. Experiments and simulations show that the
DPA circuitry locks when the data patterns listed in
repeated for the specified number of times. There are other suitable
patterns not shown in
may vary. The circuit can adjust for any phase variation that may occur
during operation.
Phase Synchronizer
Each receiver has its own phase synchronizer. The receiver phase
synchronizer aligns the phase of the parallel data from all the receivers to
one global clock. The synchronizers in each channel consist of a 4-bit deep
and J-bit wide FIFO buffer. The parallel clock writes to the FIFO buffer
and the global clock (GCLK) reads from the FIFO buffer. The global and
parallel clock inputs into the synchronizers must have identical
frequencies and differ only in phase. The FIFO buffer never becomes full
or empty (because the source and receive signals are frequency locked)
when operating within the DPA specifications, and the operation does
not require an empty/full flag or read/write enable signals.
Receiver Data Realignment In DPA Mode
While DPA operation aligns the incoming clock phase to the incoming
data phase, it does not guarantee the parallelization boundary or byte
boundary. When the dynamic phase aligner realigns the data bits, the bits
may be shifted out of byte alignment, as shown in
SPI-4, NPSI
RapidIO
Other designs
SFI-4, XSBI
Table 3–4. Training Patterns for Different Protocols
Protocols
Ten 0’s, ten 1’s
(
Four 0’s, four 1’s (
two 0’s, one 1, four 0’s (
Eight alternating 1’s and 0’s (
01010101
Not specified
00000000001111111111
Table 3–4
)
Training Pattern
and/or pattern lengths, but the lock time
00001111
10010000
10101010
) or one 1,
)
)
Figure
Table 3–4
Altera Corporation
or
3–10.
August 2005
Repetitions
Number of
are
256