Using Sequential Always Blocks - 2023.1 English

Vivado synthesis supports sequential always blocks.

• Describe a sequential circuit with an always block and a sensitivity list that contains the following edge-triggered (with posedge or negedge) events:
  • A mandatory clock event
  • Optional set/reset events (modeling asynchronous set/reset control logic)
• If no optional asynchronous signal is described, the always block is structured as follows:

  always @(posedge CLK) begin
  <synchronous_part> end

• If optional asynchronous control signals are modeled, the always block is structured as follows:

  always @(posedge CLK or posedge ACTRL1 or à ) begin
  if (ACTRL1)
  <$asynchronous part> else
  <$synchronous_part> end