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//
// Copyright 2011-2013 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/>.
//
//! The USRP digital up-conversion chain
module duc_chain
#(
parameter BASE = 0,
parameter DSPNO = 0,
parameter WIDTH = 24
)
(input clk, input rst, input clr,
input set_stb, input [7:0] set_addr, input [31:0] set_data,
// To TX frontend
output [WIDTH-1:0] tx_fe_i,
output [WIDTH-1:0] tx_fe_q,
// From TX control
input [31:0] sample,
input run,
output strobe,
output [31:0] debug
);
wire [17:0] scale_factor;
wire [31:0] phase_inc;
reg [31:0] phase;
wire [7:0] interp_rate;
wire [3:0] tx_femux_a, tx_femux_b;
wire enable_hb1, enable_hb2;
wire rate_change;
setting_reg #(.my_addr(BASE+0)) sr_0
(.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
.in(set_data),.out(phase_inc),.changed());
setting_reg #(.my_addr(BASE+1), .width(18)) sr_1
(.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
.in(set_data),.out(scale_factor),.changed());
setting_reg #(.my_addr(BASE+2), .width(10)) sr_2
(.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
.in(set_data),.out({enable_hb1, enable_hb2, interp_rate}),.changed(rate_change));
// Strobes are all now delayed by 1 cycle for timing reasons
wire strobe_cic_pre, strobe_hb1_pre, strobe_hb2_pre;
reg strobe_cic = 1;
reg strobe_hb1 = 1;
reg strobe_hb2 = 1;
assign strobe = strobe_hb1;
cic_strober #(.WIDTH(8))
cic_strober(.clock(clk),.reset(rst),.enable(run & ~rate_change),.rate(interp_rate),
.strobe_fast(1),.strobe_slow(strobe_cic_pre) );
cic_strober #(.WIDTH(2))
hb2_strober(.clock(clk),.reset(rst),.enable(run & ~rate_change),.rate(enable_hb2 ? 2 : 1),
.strobe_fast(strobe_cic_pre),.strobe_slow(strobe_hb2_pre) );
cic_strober #(.WIDTH(2))
hb1_strober(.clock(clk),.reset(rst),.enable(run & ~rate_change),.rate(enable_hb1 ? 2 : 1),
.strobe_fast(strobe_hb2_pre),.strobe_slow(strobe_hb1_pre) );
always @(posedge clk) strobe_hb1 <= strobe_hb1_pre;
always @(posedge clk) strobe_hb2 <= strobe_hb2_pre;
always @(posedge clk) strobe_cic <= strobe_cic_pre;
// NCO
always @(posedge clk)
if(rst)
phase <= 0;
else if(~run)
phase <= 0;
else
phase <= phase + phase_inc;
wire signed [17:0] da, db;
wire signed [35:0] prod_i, prod_q;
assign tx_fe_i = prod_i[33:34-WIDTH];
assign tx_fe_q = prod_q[33:34-WIDTH];
wire [17:0] i_interp, q_interp;
wire [17:0] hb1_i, hb1_q, hb2_i, hb2_q;
wire [7:0] cpo = enable_hb2 ? ({interp_rate,1'b0}) : interp_rate;
// Note that max CIC rate is 128, which would give an overflow on cpo if enable_hb2 is true,
// but the default case inside hb_interp handles this
hb_interp #(.IWIDTH(18),.OWIDTH(18),.ACCWIDTH(WIDTH)) hb_interp_i
(.clk(clk),.rst(rst),.bypass(~enable_hb1),.cpo(cpo),.stb_in(strobe_hb1),.data_in({sample[31:16], 2'b0}),.stb_out(strobe_hb2),.data_out(hb1_i));
hb_interp #(.IWIDTH(18),.OWIDTH(18),.ACCWIDTH(WIDTH)) hb_interp_q
(.clk(clk),.rst(rst),.bypass(~enable_hb1),.cpo(cpo),.stb_in(strobe_hb1),.data_in({sample[15:0], 2'b0}),.stb_out(strobe_hb2),.data_out(hb1_q));
small_hb_int #(.WIDTH(18)) small_hb_interp_i
(.clk(clk),.rst(rst),.bypass(~enable_hb2),.stb_in(strobe_hb2),.data_in(hb1_i),
.output_rate(interp_rate),.stb_out(strobe_cic),.data_out(hb2_i));
small_hb_int #(.WIDTH(18)) small_hb_interp_q
(.clk(clk),.rst(rst),.bypass(~enable_hb2),.stb_in(strobe_hb2),.data_in(hb1_q),
.output_rate(interp_rate),.stb_out(strobe_cic),.data_out(hb2_q));
cic_interp #(.bw(18),.N(4),.log2_of_max_rate(7))
cic_interp_i(.clock(clk),.reset(rst),.enable(run & ~rate_change),.rate(interp_rate),
.strobe_in(strobe_cic),.strobe_out(1),
.signal_in(hb2_i),.signal_out(i_interp));
cic_interp #(.bw(18),.N(4),.log2_of_max_rate(7))
cic_interp_q(.clock(clk),.reset(rst),.enable(run & ~rate_change),.rate(interp_rate),
.strobe_in(strobe_cic),.strobe_out(1),
.signal_in(hb2_q),.signal_out(q_interp));
localparam cwidth = WIDTH; // was 18
localparam zwidth = 24; // was 16
wire [cwidth-1:0] da_c, db_c;
cordic_z24 #(.bitwidth(cwidth))
cordic(.clock(clk), .reset(rst), .enable(run),
.xi({i_interp,{(cwidth-18){1'b0}}}),.yi({q_interp,{(cwidth-18){1'b0}}}),
.zi(phase[31:32-zwidth]),
.xo(da_c),.yo(db_c),.zo() );
MULT18X18S MULT18X18S_inst
(.P(prod_i), // 36-bit multiplier output
.A(da_c[cwidth-1:cwidth-18]), // 18-bit multiplier input
.B(scale_factor), // 18-bit multiplier input
.C(clk), // Clock input
.CE(1), // Clock enable input
.R(rst) // Synchronous reset input
);
MULT18X18S MULT18X18S_inst_2
(.P(prod_q), // 36-bit multiplier output
.A(db_c[cwidth-1:cwidth-18]), // 18-bit multiplier input
.B(scale_factor), // 18-bit multiplier input
.C(clk), // Clock input
.CE(1), // Clock enable input
.R(rst) // Synchronous reset input
);
assign debug = {strobe_cic, strobe_hb1, strobe_hb2,run};
endmodule // duc_chain
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