LatticeECP/EC and LatticeXP
Lattice Semiconductor
sysCLOCK PLL Design and Usage Guide
11-5
FDEL Settings
There are four ways the user can enter the desired FDEL value.
1. Although the FDEL entry is not available in the IPexpress GUI, the module generated by IPexpress
includes the attribute with default value, “0”. Users can replace it with a desired value.
Example of source code with default FDEL value:
attribute FDEL of ehxpll_mod_0_0 : label is "0";
generic map (…
FDEL=>"0",
…
")
2. Preference File: User may specify the preference in the Preference file.
Example:
ASIC "FDEL_CODE_0_0" TYPE "EHXPLLB" FDEL="-2"
;
3. Pre-Map Preference Editor: Users can enter the FDEL value in the Pre-Map Preference Editor as shown in
CLKOP Actual
Frequency
YN
N
MHz
CLKOK Frequency
Tolerance
Y
N
0.0, 0.1, 0.2, 0.5,1.0, 2.0, 5.0, 10.0
0.0
%
CLKOK Actual
Frequency
YN
N
MHz
CLKI Divider
Setting
YCLKI_DIV
4, 6
Y
N
1 to 16 (1 to 15)
1
CLKFB Divider
Setting
Y
CLKFB_DIV
6
Y
N
1 to 16 (1 to 15)
1
CLKOP Divider
Setting
Y
CLKOP_DIV
6
Y
N
Note 3
8
2 (4 or 6)
CLKOK Divider
Setting
Y
CLKOK_DIV
Y
N
2, 4, 6,..,126, 128
2
Fine Delay Adjust
N
FDEL
Y
-8 to 8
0
ps
Coarse Phase Shift
Selection (O)
Y
PHASEADJ
Y
N
0, 45, 90...315
0
Degrees
Duty Cycle Selection
(1/8 increment)
Y
DUTY
Y
N
1 to 7
4
Delay Control
Y
DELAY_CNTL1
Y
N
DYNAMIC/STATIC
STATIC
Feedback Mode
Y
FB_MODE
N
INTERNAL/CLOCKTREE/EXTERNAL
CLOCKTREE
CLKOS Select
Y
N
CLKOK Select
Y
N
1. DYNAMIC: This mode switches delay control between Dynamic and Static depending upon the input logic of the DDAMODE pin.
STATIC: This is Static Control Only mode.
2. The CLKOP_DIV value is calculated to maximize the fVCO within the specified range. For LatticeXP devices, if CLKOS is not used, the
default value is 6. If CLKOS is used, the value is 4.
3. The CLKOP Divider values are 2, 4, 6, 8,..32 (2, 4, 6, 8..30 for LatticeXP devices) if CLKOS is not used. The CLKOP Divider values are 2,
4, 8, 16, 32 (2, 4, 8, 16 for LatticeXP devices) if CLKOS is used.
4. All divider settings are user transparent in Frequency Mode. These are user attributes in Divider Mode.
5. Refer to data sheet for frequency limits.
6. Values in parentheses are for LatticeXP devices.
7. This attribute is not available in the IPexpress GUI. After reviewing the trace report file, users can determine the amount of delay that will
best fit the clocking in their design. Further information on FDEL settings is described in the following section.
Table 11-2. LatticeECP/EC and LatticeXP PLL Attributes (Continued)
User
Accessible
IPexpress
GUI Access
Attribute
Name
Preference
Language
Support
Preference
Editor
Support
Value
Default
Value
Units