ECP5 and ECP5-5G High-Speed I/O Interface
Technical Note
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FPGA-TN-02035-1.3
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Table 8.5. DDRDLLA Port List
Port
I/O
Description
CLK
I
Reference clock input to the DDRDLL. Should run at the same frequency as the clock to be delayed.
RST
I
Reset input to the DDRDLL
UDDCNTLN
I
Update control to update the delay code. When low, the delay code out of the DDRDLL is updated.
Should not be active during a read or a write cycle.
FREEZE
I
Releases the DDRDLL input clock
DDRDEL
O
The delay codes from the DDRDLL to be used in DQSBUF or DLLDEL
LOCK
O
Lock output to indicate the DDRDLL has valid delay output
DCNTL [7:0]
O
The delay codes from the DDRDLL available for the user IP.
Table 8.6. DDRDLL Attributes
Attribute
Description
Values
Default
FORCE_MAX_DELAY
*
Bypass DLL locking procedure at low frequency
YES, NO
NO
*
Note
: When Fin is =<30 MHz. The software sets Force_max_delay to YES. DDRDLL does not go through the locking process but is
locked to maximum delay steps under such conditions.
8.6.
DLL Delay (DLLDEL)
The DLLDEL receive delay codes from the DDRDLL and generates a delayed clock output.
The DLLDEL receives delay from the DDRDLL. The delayed clock output of the DLLDEL can be connected to the IDDR
module.
The delay from the DLLDEL can be dynamically adjusted using counter margin control signals that can shift the delay up
or down.DLLDELD
DLLDELD
Z
A
DDRDEL
LOADN
MOVE
DIRECTION
CFLAG
Figure 8.4. DLLDELD Primitive
Table 8.7. DLLDELD Port List
Port
I/O
Description
A
I
Clock input
DDRDEL
I
Delay inputs from DDRDLL
LOADN
I
Used to reset back to 90° delay.
MOVE
I
Pulse is required to change delay settings. The value on Direction is sampled at the falling edge of
MOVE.
DIRECTION
I
Indicates delay direction.
1
to decrease delay and
0
to increase delay
CFLAG
O
Indicates the delay counter has reached its maximum value when moving up or minimum value
when moving down.
Z
O
Delayed clock output