
Chapter 3: Functional Description 3–9
Device-Level Description
© March 2009 Altera Corporation DDR and DDR2 SDRAM Controller Compiler User Guide
Figure 3–4. Stratix II DQS Group Block Diagram (Note 1) (2)
Notes to Figure 3–4:
(1) This figure shows the logic for one DQ output only. A complete byte group consists of eight times the DQ logic with the DQS and DM logic.
(2) All clocks are clk, unless marked otherwise.
(3) Invert combout of the I/O element (IOE) for the dqs pin before feeding in to inclock of the IOE for the DQ pin. This inversion is automatic if
you use an ALTDQ megafunction for the DQ pins.
(4) The optional inverters are controlled by the resynchronization edge and postamble edge settings on the Manual Timings tab, refer to “Manual
Timing Settings” on page A–1
DQ D
write_clk
DQS
DM
dqs_oe
1
DQS Delay
Ao
Bo
Q
0
1
DQ
DQ
0
1
DQS IOEs
DM altddio Megafunction
DQ
DQ
Q
Q
D
D
be
doing_wr
dqs_burst
Q
D
2
Q
D
Q
D
QD QD
QDQD
QD
D
Q
Q Q
DQ
D
D
Q
DQ
wdata
DQ
write_clk
doing_wr
rdata
doing_rd
(pipelined)
postamble_clk
resynched_data
dq_capture_clk
resynch_clk
dq_oe
16
0
1
16
8
8
8
D
EN
EN
doing_wr
EN
EN
wdata_valid
DQ IOEs
dq_enable_reset
Preset (asynchronous)
(Note 3)
Optional Inverter (Note 4)
Optional Inverters (Note 4)
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