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Altera_Forum's avatar
Altera_Forum
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8 years ago

How declare ALM synchronous signal (enable, sload, sclear) in vhdl

Hello.

The basic cell in Intel FPGA have a wonderful architecture, including dedicated synchronous signals as enable, sload and sclear. However, describe the use of this resources is not easy in vhdl for me. I use "process" only for declare hardware associated whit registers.

Declare "enable" is easy:

if (enable) then --this use enable dedícate port

q <= xxxx;

end if;

Declare "sclear"...

if (sclr) then

--this use in RTL and Chip Planner a mux! i want sclr dedícate port

q <= (others => '0');

end if;

Declare "enable" and "sclear" use two mux. Now don't use enable dedícate port.

How can use these precious resourses, synchronous dedícate ports?

Thanks!!

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1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    8 years ago

    You can access a complete template for all secondary control signals using the Edit menu in the Quartus text editor. But here is a similar complete template. Just remove the signals you don't want to use: 

    ARCHITECTURE behavior OF dff IS
BEGIN
PROCESS(clk, aclr, apre, aload, adata)
BEGIN
    IF aclr = '1' THEN
        q <= '0';
    ELSIF apre = '1' THEN
        q <= '1';
    ELSIF aload = '1' THEN
        q <= adata;
    ELSIF rising_edge(clk) THEN
        IF ena = '1' THEN
            IF sclr = '1' THEN
                q <= '0';
            ELSIF sload = '1' THEN
                q <= sdata;
            ELSE
                q <= d;
            END IF;
        END IF;
    END IF;
END PROCESS;
END ARCHITECTURE behavior;