3 // USRP - Universal Software Radio Peripheral
5 // Copyright (C) 2007 Corgan Enterprises LLC
7 // This program is free software; you can redistribute it and/or modify
8 // it under the terms of the GNU General Public License as published by
9 // the Free Software Foundation; either version 2 of the License, or
10 // (at your option) any later version.
12 // This program is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 51 Franklin Street, Boston, MA 02110-1301 USA
22 module sounder_rx(clk_i,rst_i,ena_i,rx_strobe_i,tx_strobe_i,mask_i,len_i,
23 rx_in_i_i,rx_in_q_i,rx_i_o,rx_q_o,rx_strobe_o);
25 input clk_i; // Master clock
26 input rst_i; // Subsystem reset
27 input ena_i; // Subsystem enable
28 input rx_strobe_i; // Strobe every received sample
29 input tx_strobe_i; // Strobe every transmitted sample
31 input [15:0] mask_i; // PN code LFSR mask
32 input [15:0] len_i; // PN code LFSR sequence length
33 input [15:0] rx_in_i_i; // I channel on receive
34 input [15:0] rx_in_q_i; // Q channel on receive
36 output [15:0] rx_i_o; // I channel of impulse response
37 output [15:0] rx_q_o; // Q channel of impulse response
38 output rx_strobe_o; // Impulse response value ready
42 wire cycle = (count == (len_i - 1));
44 always @(posedge clk_i)
51 count <= count + 16'b1;
53 // Retard LFSR phase once per cycle
54 wire lfsr_strobe = (tx_strobe_i & ~cycle);
56 // Recreate local reference of transmitted PN code
59 ( .clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i),.strobe_i(lfsr_strobe),.mask_i(mask_i),.pn_o(pn) );
61 wire [31:0] rx_i_ext, rx_q_ext;
62 sign_extend #(16,32) i_extend(rx_in_i_i, rx_i_ext);
63 sign_extend #(16,32) q_extend(rx_in_q_i, rx_q_ext);
66 always @(posedge clk_i)
75 accum <= accum + rx_i_ext;
77 accum <= accum - rx_i_ext;
79 assign rx_i_o = accum[31:16];
80 assign rx_q_o = accum[15:0];
81 assign rx_strobe_o = rx_strobe_i & cycle;
83 endmodule // sounder_rx