Getting a task done in another clock domain

Getting a task done in another clock domain
If 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 [2:0] SyncA_clkB, SyncB_clkA;always @(posedge clkA) if(TaskStart_clkA & ~TaskBusy_clkA) FlagToggle_clkA <= ~FlagToggle_clkA;always @(posedge clkB) SyncA_clkB <= {SyncA_clkB[1:0], FlagToggle_clkA};assign TaskStart_clkB = (SyncA_clkB[2] ^ SyncA_clkB[1]);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[1:0], FlagToggle_clkB};assign TaskBusy_clkA = FlagToggle_clkA ^ SyncB_clkA[2];assign TaskDone_clkA = SyncB_clkA[2] ^ SyncB_clkA[1];endmoduleand here's a matching simulation waveform