Merged r10770:10887 from jcorgan/iad2 into trunk. Adds alternative USRP2 FPGA build to use integrate-and-dump decimator instead of CIC/HB combination. This provides a much shorter time duration impulse response for the same decimation rate, at the expense of worse stop-band rejection.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@10888 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 63 insertions, 0 deletions

diff --git a/top/u2_rev3_iad/impulse.v b/top/u2_rev3_iad/impulse.v
new file mode 100644
index 000000000..ecdf101ab
--- /dev/null
+++ b/top/u2_rev3_iad/impulse.v
@@ -0,0 +1,63 @@
+module impulse
+  (input clk,
+   input rst,
+   input ena,
+   
+   input [13:0] dc_offset_a,
+   input [13:0] dc_offset_b,
+   input [13:0] amplitude,
+   input [15:0] impulse_len,
+   input [15:0] zero_len,
+
+   output [13:0] adc_a,
+   output [13:0] adc_b,
+   output        adc_ovf_a,
+   output        adc_ovf_b
+   );
+
+   reg [13:0] adc_a_int = 0;
+   reg [15:0] count;
+
+   localparam ST_ZERO = 0;
+   localparam ST_HIGH = 1;
+   reg 	      state;
+   
+   always @(posedge clk)
+     if (rst | ~ena)
+       begin
+	  adc_a_int <= 0;
+	  count <= 0;
+	  state <= ST_ZERO;
+       end
+     else
+       case(state)
+	 ST_ZERO:
+	   if (count == zero_len)
+	     begin
+		adc_a_int <= amplitude;
+		state <= ST_HIGH;
+		count <= 0;
+	     end
+	   else
+	     count <= count + 1;
+
+	 ST_HIGH:
+	   if (count == impulse_len)
+	     begin
+		adc_a_int <= 0;
+		state <= ST_ZERO;
+		count <= 0;
+	     end
+	   else
+	     count <= count + 1;
+
+       endcase // case (state)
+
+   assign adc_a = adc_a_int + dc_offset_a;
+
+   // Ignore for now
+   assign adc_b = dc_offset_b;
+   assign adc_ovf_a = 0;
+   assign adc_ovf_b = 0;
+
+endmodule // adc_model