-- VHDL program to turn on the LED light. -- It has to be properly loaded to the FPGA device. -- Pin assignments for "clk" and "led" signals need -- to be done for this purpose. LIBRARY ieee; USE ieee.std_logic_1164.ALL; -- Entity part is a specification of the circuit interface; -- it tells how the circuit will interact with its environment. ENTITY HelloWorld is PORT (clk: IN std_logic; led: OUT std_logic); END HelloWorld; -- Architecture part is a description of the circuit behavior ARCHITECTURE archOfHelloWorld OF HelloWorld IS -- Declaration part precedes the BEGIN SIGNAL blink : std_logic; BEGIN -- PROCESS executes whenever its input signal changes PROCESS(clk) BEGIN if rising_edge(clk) then blink <= not blink; -- for the led to change state end if; END PROCESS; led <= blink; END archOfHelloWorld;