1 files changed, 35 insertions, 0 deletions
diff --git a/control_lib/oneshot_2clk.v b/control_lib/oneshot_2clk.v
new file mode 100644
index 000000000..72f16a4b3
--- /dev/null
+++ b/control_lib/oneshot_2clk.v
@@ -0,0 +1,35 @@
+
+// Retime a single bit from one clock domain to another
+// Guarantees that no matter what the relative clock rates, if the in signal is high for at least
+//   one clock cycle in the clk_in domain, then the out signal will be high for at least one
+//   clock cycle in the clk_out domain.  If the in signal goes high again before the process is done
+//   the behavior is undefined.  No other guarantees.  Designed for passing reset into a new
+//   clock domain.
+
+module oneshot_2clk
+  (input clk_in,
+   input in,
+   input clk_out,
+   output reg out);
+
+   reg 	  del_in = 0;
+   reg 	  sendit = 0, gotit = 0;
+   reg 	  sendit_d = 0, gotit_d = 0;
+   
+   always @(posedge clk_in) del_in <= in;
+
+   always @(posedge clk_in)
+     if(in & ~del_in)  // we have a positive edge
+       sendit <= 1;
+     else if(gotit)
+       sendit <= 0;
+
+   always @(posedge clk_out) sendit_d <= sendit;
+   always @(posedge clk_out) out <= sendit_d;
+
+   always @(posedge clk_in) gotit_d <= out;
+   always @(posedge clk_in) gotit <= gotit_d;
+
+endmodule // oneshot_2clk
+
+