Asynchronous vs Synchronous Control
Some LPMS have both synchronous and asynchronous control lines
- Counter has ‘aload’ (asynchronous load), and ‘sload’ (synchronous load); ‘aclr’ and ‘sclr’ (async and sync clear)
Should always use a Synchronous control line if possible, especially if connected to a FSM output.
- Any glitch on an asychronous control line can trigger it
- If using a FSM output for an asynchronous control, the output should come directly from a Flip-Flop output, NOT from combinational gating.