Why is this an issue?

To improve reliability, use rising_edge and falling_edge functions instead of other clock transition implementations such as:

• clk'event and clk='1'
• not clk'stable and clk='1'

How to fix it

Code examples

Noncompliant code example

process(clk) is
begin
  if clk'event and clk='1' then -- Noncompliant
    o1 <= not i1;
  end if;
end process;

Compliant solution

process(clk) is
begin
  if rising_edge(clk) then -- Compliant
    o1 <= not i1;
  end if;
end process;

Resources

Articles & blog posts

• Difference between rising_edge(clk) and (clk'event and clk='1')