ECP5 and ECP5-5G High-Speed I/O Interface
Technical Note
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72
FPGA-TN-02035-1.3
Generates the Read and Write pointers required in the IDDR to correctly transfer data between the DQS and ECLK
clock domains
Generates DQS write clocks to be used in ODDR modules to generate DQ and DQS
Generates the Write Leveling delay required for DDR3 or LPDDR3 interfaces
8.10.2.
DQSBUFM
DQSBUFM element is used for all the DDR Memory interfaces.
DQSBUFM
DQSI
DQSR 90
DQSW
DATAVALID
DDRDEL
READ [1:0]
ECLK
WRPNTR [2:0]
RDPNTR [2:0]
SCLK
RST
DYNDELAY [7:0]
READCLKSEL0
BURSTDET
DQSW 270
READCLKSEL1
READCLKSEL2
RDLOADN
RDMOVE
RDDIRECTION
RDCFLAG
WRLOADN
WRMOVE
WRDIRECTION
WRCFLAG
PAUSE
Figure 8.11. DQSBUFM Primitive
Table 8.15. DQSBUF Port List
Port
I/O
Description
DQSI
I
DQS input from the DQS pin
DDRDEL
I
Delay code from DDRDLL
ECLK
I
Edge Clock
SCLK
I
System Clock
RST
I
Reset input
READ[1:0]
I
Read input width for DQSBUFM
READCLKSEL0,
READCLKSEL1,
READCLKSEL2
I
Read clock pulse selection
DYNDELAY[7:0]
I
Dynamic Write leveling delay (only for DDR3)
PAUSE
I
Pause input to stop the DQSW/DQSW270 during write leveling or DDRDLL delay code change.
RDLOADN
I
Used to reset back to 90° delay for read side DQS
RDMOVE
I
Pulse is required to change delay settings. The value on Direction is sampled at
falling edge
of
MOVE. Used to change delay on the read side DQS.
RDDIRECTION
I
Indicates delay direction.
1
decreases the delay count,
0
increases the delay count. Used to
change delay on the read side DQS.