Getting a task done in another clock domain
Getting a task done in another clock domainIf the clkA domain has a task that needs to be completed in the clkB domain, you can use the following design.
Here's one way to do it
module TaskAck_CrossDomain( clkA, TaskStart_clkA, TaskBusy_clkA, TaskDone_clkA, clkB, TaskStart_clkB, TaskBusy_clkB, TaskDone_clkB);// clkA domain signalsinput clkA;input TaskStart_clkA;output TaskBusy_clkA, TaskDone_clkA;// clkB domain signalsinput clkB;output TaskBusy_clkB, TaskStart_clkB;input TaskDone_clkB;reg FlagToggle_clkA, FlagToggle_clkB, Busyhold_clkB;reg SyncA_clkB, SyncB_clkA;always @(posedge clkA) if(TaskStart_clkA & ~TaskBusy_clkA) FlagToggle_clkA <= ~FlagToggle_clkA;always @(posedge clkB) SyncA_clkB <= {SyncA_clkB, FlagToggle_clkA};assign TaskStart_clkB = (SyncA_clkB ^ SyncA_clkB);assign TaskBusy_clkB = TaskStart_clkB | Busyhold_clkB;always @(posedge clkB) Busyhold_clkB <= ~TaskDone_clkB & TaskBusy_clkB;always @(posedge clkB) if(TaskBusy_clkB & TaskDone_clkB) FlagToggle_clkB <= FlagToggle_clkA;always @(posedge clkA) SyncB_clkA <= {SyncB_clkA, FlagToggle_clkB};assign TaskBusy_clkA = FlagToggle_clkA ^ SyncB_clkA;assign TaskDone_clkA = SyncB_clkA ^ SyncB_clkA;endmoduleand here's a matching simulation waveform
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