ECP5 and ECP5-5G High-Speed I/O Interface
Technical Note
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FPGA-TN-02035-1.3
15
5.
High-Speed DDR Interface Details
This section describes each of the generic high-speed interfaces in detail, including the clocking to be used for each
interface. For detailed information about the ECP5 and ECP5-5G device clocking structure, refer to
sysClock PLL/DLL Design and Usage Guide (FPGA-TN-02200)
. The various interface rules listed under each interface
should be followed to build these interfaces successfully. Refer to the
Timing Analysis for High Speed DDR Interfaces
section for more information about the timing analysis on these interfaces.
Some of these interfaces may require a soft IP in order utilize all the features available in the hardware. These soft IP
cores are available in Clarity Designer and are described in this section. Some of the soft IPs are optional and can be
selected in the Clarity Designer. Some of these are mandatory for the module to function as expected and are
automatically generated when building the interface through Clarity Designer.
5.1.
GDDRX1_RX.SCLK.Centered
This a Generic 1x gearing Receive interface using SCLK. The clock is coming in centered to the data. This interface must
be used for speeds below 250 MHz.
This DDR interface uses the following modules:
IDDRX1F element to capture the data
The incoming clock is routed through the Primary (SCLK) clock tree
Static data delay element DELAYG is used to delay the incoming data enough to remove the clock injection time.
Optionally, you can choose to use Dynamic Data Delay adjustment using DELAYF element to control the delay on
the DATA dynamically. DELAYF also allows you to override the input delay set. The type of delay required can be
selected through Clarity Designer.
DEL_MODE attribute is used with DELAYG and DELAYF element to indicate the interface type so that the correct
delay value can be set in the delay element.
The following figures show the static delay and dynamic delay options for this interface.
Figure 5.1. GDDRX1_RX.SCLK.Centered Interface (Static Delay)
Figure 5.2. GDDRX1_RX.SCLK.Centered Interface (Dynamic Data Delay)
Interface Requirements
The clock input must use a PCLK input so that it can be routed directly to the primary clock tree.
You must set the timing preferences as indicated in the
Timing Analysis for High Speed DDR Interfaces
section.