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ECP5 and ECP5-5G sysCLOCK
PLL/DLL Design and Usage Guide
Figure 30. Clarity Designer Main Window for PLL Module
Configuration Tab
The configuration window lists all user accessible attributes with default values set. Upon completion, clicking Gen-
erate generates the source.
PLL Frequency and Phase Configuration
Enter the input and output clock frequencies and the software will calculate the divider settings. After the input and
output frequencies are entered clicking the Calculate button will display the divider values and the closest achiev-
able frequency will be displayed in the “Actual Frequency” text box. If an entered value is out of range it will be dis-
played in red and an error message will be displayed. The user can also select a tolerance value from the
“Tolerance %” drop-down box. When the Calculate button is pressed the calculation will be considered accurate if
the result is within the entered tolerance percentage range.
New to the ECP5 and ECP5-5G PLL GUI, the user enters the desired phase shift and the software will calculate
the closest achievable shift. After the desired phase is entered, clicking the Calculate button will display the closest
achievable phase shift in the “Actual Phase” text box. If an entered value is out of range it will be displayed in red
and an error message will be displayed.