1 files changed, 22 insertions, 5 deletions
diff --git a/usrp2/gpif/fifo36_to_gpmc16.v b/usrp2/gpif/fifo36_to_gpmc16.v
index 508cd319c..4b4dc3109 100644
--- a/usrp2/gpif/fifo36_to_gpmc16.v
+++ b/usrp2/gpif/fifo36_to_gpmc16.v
@@ -17,7 +17,10 @@
 
 module fifo36_to_gpmc16
 #(
-    parameter FIFO_SIZE = 9
+    parameter FIFO_SIZE = 9,
+
+    //not ready until minimum xfers of occupancy available
+    parameter MIN_OCC16 = 2
 )
 (
     //input fifo interface
@@ -31,22 +34,36 @@ module fifo36_to_gpmc16
     output [15:0] out_data,
     output valid,
     input enable,
-    output eof
+    output eof,
+    output reg has_data
 );
 
+    wire [15:0] fifo_occ;
+
+    always @(posedge gpif_clk)
+        has_data <= (fifo_occ >= MIN_OCC16);
+
     wire [35:0] data_int;
     wire src_rdy_int, dst_rdy_int;
 
-    fifo_2clock_cascade #(.WIDTH(36), .SIZE(FIFO_SIZE)) fifo_2clk
+    fifo_2clock_cascade #(.WIDTH(36), .SIZE(6)) fifo_2clk
      (.wclk(fifo_clk), .datain(in_data), .src_rdy_i(in_src_rdy), .dst_rdy_o(in_dst_rdy), .space(),
       .rclk(gpif_clk), .dataout(data_int), .src_rdy_o(src_rdy_int), .dst_rdy_i(dst_rdy_int), .occupied(),
       .arst(fifo_rst | gpif_rst));
 
-    wire [18:0] data18_int;
+    wire [18:0] data19_int;
+    wire data19_src_rdy_int, data19_dst_rdy_int;
+
     fifo36_to_fifo19 #(.LE(1)) f36_to_f19
      (.clk(gpif_clk), .reset(gpif_rst), .clear(1'b0),
       .f36_datain(data_int), .f36_src_rdy_i(src_rdy_int), .f36_dst_rdy_o(dst_rdy_int),
-      .f19_dataout(data18_int), .f19_src_rdy_o(valid), .f19_dst_rdy_i(enable) );
+      .f19_dataout(data19_int), .f19_src_rdy_o(data19_src_rdy_int), .f19_dst_rdy_i(data19_dst_rdy_int) );
+
+    wire [17:0] data18_int;
+    fifo_cascade #(.WIDTH(18), .SIZE(FIFO_SIZE+1)) occ_ctrl_fifo
+     (.clk(gpif_clk), .reset(gpif_rst), .clear(1'b0),
+      .datain(data19_int[17:0]), .src_rdy_i(data19_src_rdy_int), .dst_rdy_o(data19_dst_rdy_int), .space(),
+      .dataout(data18_int), .src_rdy_o(valid), .dst_rdy_i(enable), .occupied(fifo_occ));
 
     assign out_data = data18_int[15:0];
     assign eof = data18_int[17];