1 files changed, 130 insertions, 0 deletions
diff --git a/fpga/usrp2/custom/power_trig.v b/fpga/usrp2/custom/power_trig.v
new file mode 100644
index 000000000..b38059030
--- /dev/null
+++ b/fpga/usrp2/custom/power_trig.v
@@ -0,0 +1,130 @@
+//
+// Copyright 2012 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+// This a power trigger module implemented on top of the custom dsp template.
+// Power triggering is implemented after the existing DDC chain.
+// Triggering is controlled via user settings registers.
+
+// Register 0:
+//  threshold for power trigger
+//  32 bit unsigned fixed-point number of some arbitrary scaling
+
+module power_trig
+#(
+    //frontend bus width
+    parameter WIDTH = 24,
+    parameter BASE = 0
+)
+(
+    //control signals
+    input clock, //dsp clock
+    input reset, //active high synchronous reset
+    input clear, //active high on packet control init
+    input enable, //active high when streaming enabled
+
+    //user settings bus, controlled through user setting regs API
+    input set_stb, input [7:0] set_addr, input [31:0] set_data,
+
+    //full rate inputs directly from the RX frontend
+    input [WIDTH-1:0] frontend_i,
+    input [WIDTH-1:0] frontend_q,
+
+    //full rate outputs directly to the DDC chain
+    output [WIDTH-1:0] ddc_in_i,
+    output [WIDTH-1:0] ddc_in_q,
+
+    //strobed samples {I16,Q16} from the RX DDC chain
+    input [31:0] ddc_out_sample,
+    input ddc_out_strobe, //high on valid sample
+    output ddc_out_enable, //enables DDC module
+
+    //strobbed baseband samples {I16,Q16} from this module
+    output [31:0] bb_sample,
+    output bb_strobe //high on valid sample
+);
+
+    //leave frontend tied to existing ddc chain
+    assign ddc_in_i = frontend_i;
+    assign ddc_in_q = frontend_q;
+
+    //ddc enable remains tied to global enable
+    assign ddc_out_enable = enable;
+
+    //below we implement a power trigger between baseband samples and ddc output...
+
+   reg [8:0] 	  wr_addr;
+   wire [8:0] 	  rd_addr;
+   reg 		  triggered, triggerable;
+   wire 	  trigger;
+   
+   wire [31:0] 	  delayed_sample;
+   wire [31:0] 	  thresh;
+   
+   setting_reg #(.my_addr(BASE+0)) sr_0
+     (.clk(clk),.rst(reset),.strobe(set_stb),.addr(set_addr),
+      .in(set_data),.out(thresh),.changed());
+
+   assign rd_addr = wr_addr + 1; // FIXME adjustable delay
+
+   ram_2port  #(.DWIDTH(32),.AWIDTH(9)) delay_line
+     (.clka(clk),.ena(1),.wea(ddc_out_strobe),.addra(wr_addr),.dia(ddc_out_sample),.doa(),
+      .clkb(clk),.enb(ddc_out_strobe),.web(1'b0),.addrb(rd_addr),.dib(32'hFFFF),.dob(delayed_sample));
+
+   always @(posedge clock)
+     if(reset | ~enable)
+       wr_addr <= 0;
+     else
+       if(ddc_out_strobe)
+	 wr_addr <= wr_addr + 1;
+
+   always @(posedge clock)
+     if(reset | ~enable)
+       triggerable <= 0;
+     else if(wr_addr == 9'h1FF)  // Wait till we're nearly full
+       triggerable <= 1;
+   
+
+   reg 			      stb_d1, stb_d2;
+   always @(posedge clock) stb_d1 <= ddc_out_strobe;
+   always @(posedge clock) stb_d2 <= stb_d1;
+   
+   assign bb_sample = delayed_sample;
+   assign bb_strobe = stb_d1 & triggered;
+
+   // Compute Mag
+   wire [17:0] 		      mult_in = stb_d1 ? { ddc_out_sample[15],ddc_out_sample[15:0], 1'b0 } : 
+			      { ddc_out_sample[31], ddc_out_sample[31:16], 1'b0 };
+   wire [35:0] 		      prod;
+   reg [31:0] 		      sum;
+   
+   MULT18X18S mult (.P(prod), .A(mult_in), .B(mult_in), .C(clock), .CE(ddc_out_strobe | stb_d1), .R(reset) );
+
+   always @(posedge clock)
+     if(stb_d1)
+       sum <= prod[35:4];
+     else if(stb_d2)
+       sum <= sum + prod[35:4];
+
+   always @(posedge clock)
+     if(reset | ~enable | ~triggerable)
+       triggered <= 0;
+     else if(trigger)
+       triggered <= 1;
+
+   assign trigger = (sum > thresh);
+   
+endmodule // power_trig