Connecting Function Generator with FPGA

I want to take square wave with 1Hz frequency (50% duty cycle) generated from a function generator as input to the FPGA board (Cyclone V, 5CSEMA5F31C6N). I am trying to give a square pulse of 1hz as input to the FPGA. So to test how to take an input from an external source I wrote the following basic code:

module frequency(input imp,
           output op); 
assign op = imp;  
endmodule 

The function generator output was given to the GPIO_0[0] (PIN_AC18) and output pin was chosen as: LEDR[0]. When I upload the program after pin assignment, the LEDR0 only remains high, it does not blink from high to low (since square wave oscillates from 0 to 1 and 1 to 0 at each clock cycle.

How can I solve the issue ? How can I read a digital signal from the function generator in the FPGA ?