Category: Specifications
Tools: Quartus® Prime / Quartus® II
Devices: Stratix® IV, Stratix® III, Arria® II, Cyclone® IV, Cyclone® III


When the FPGA performs initialization after configuration is completed, the initialization clock can be supplied externally instead of the internal clock of the device.
The CLKUSR pin is an external supply pin for the initializing clock.

Whether or not this pin is used is set by a Quartus® Prime / Quartus® II option.
If the CLKUSR pin is not used as a dedicated pin, it can be used as a regular user I/O pin.

[procedure]

1. Select Assignments menu ⇒ Device.
2. Click the Device&Pin Options button.
3. Turn On the Enableuser-supplied start-up clock (CLKUSR) option in the General tab. (Check it.)
4. Click the OK button.
5. Compile.