ECP5 and ECP5-5G High-Speed I/O Interface
Technical Note
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FPGA-TN-02035-1.3
8.4.
DELAY Attribute Description
describes the attributes available for the DELAYF and DELAYG elements. The value of DEL_MODE is selected
based on the interface that is generated. These values are used to compensate for the clock injection time, hence
should be selected based on clocking used. IP Express automatically assigns the correct values for this attribute when
Clarity Designer is used to build the interface.
Table 8.4. DELAYF and DELAYG Attributes
Attribute
Description
Values
1, 2, 3, 4
Default
DELAY
DEL_MODE
Sets the delay mode to be used
USER_DEFINED
SCLK_ZEROHOLD
ECLK_ALIGNED
ECLK_CENTERED
SCLK_ALIGNED
SCLK_CENTERED
ECLKBRIDGE_ALIGNED
ECLKBRIDGE_CENTER
ED DQS_CMD_CLK
DQS_ALIGNED_X2
USER_DEFINED
DELAYG
DELAYF
DEL_VALUE
Sets delay value when DEL_MODE is set to USER_DEFINED
0..127
0
DELAYG
DELAYF
Notes:
1.
DEL_MODE must be ECLKBRIDGE_ALIGNED or ECLKBRIDGE_CENTERED when it is required to place the data pins of the same
high-speed interface on the other side of the device. In addition to setting the DEL_MODE attribute, it is also required to
instantiate the ECLKBRIDGECS element in the HDL design.
2.
DQS_CMD_CLK is only for the DDR Memory CMD and CLK Output.
3.
DQS_ALIGNED_X2 is shared by DQS Generic and the DDR Memory Input.
8.5.
DDRDLL (Master DLL)
The DDRDLL is used to generate a 90
o
delay for the DQS Strobe Input during a memory interface or for the clock input
for a generic DDR interface.
There is one DDRDLL module on each corner of the device. The DDRDLL outputs delay codes that are used in the
DQSBUF elements to delay the DQS input, or in the DLLDEL module to delay the input clock. DDRDLL, by default,
generates 90
o
phase shift.
8.5.1.
DDRDLLA
CLK
RST
UDDCNTLN
FREEZE
DDRDEL
LOCK
DDRDLLA
DCNTL[7:0]
Figure 8.3. DDRDLLA Primitive