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//
// Copyright 2011 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/>.
//
module dsp_core_tx
#(parameter BASE=0)
(input clk, input rst,
input set_stb, input [7:0] set_addr, input [31:0] set_data,
output reg [15:0] dac_a,
output reg [15:0] dac_b,
// To tx_control
input [31:0] sample,
input run,
output strobe,
output [31:0] debug
);
wire [15:0] i, q, scale_i, scale_q;
wire [31:0] phase_inc;
reg [31:0] phase;
wire [7:0] interp_rate;
wire [3:0] dacmux_a, dacmux_b;
wire enable_hb1, enable_hb2;
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)) sr_1
(.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
.in(set_data),.out({scale_i,scale_q}),.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());
setting_reg #(.my_addr(BASE+4), .width(8)) sr_4
(.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
.in(set_data),.out({dacmux_b,dacmux_a}),.changed());
// 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;
cic_strober #(.WIDTH(8))
cic_strober(.clock(clk),.reset(rst),.enable(run),.rate(interp_rate),
.strobe_fast(1),.strobe_slow(strobe_cic_pre) );
cic_strober #(.WIDTH(2))
hb2_strober(.clock(clk),.reset(rst),.enable(run),.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(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;
wire [17:0] bb_i = {sample[31:16],2'b0};
wire [17:0] bb_q = {sample[15:0],2'b0};
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(24)) hb_interp_i
(.clk(clk),.rst(rst),.bypass(~enable_hb1),.cpo(cpo),.stb_in(strobe_hb1),.data_in(bb_i),.stb_out(strobe_hb2),.data_out(hb1_i));
hb_interp #(.IWIDTH(18),.OWIDTH(18),.ACCWIDTH(24)) hb_interp_q
(.clk(clk),.rst(rst),.bypass(~enable_hb1),.cpo(cpo),.stb_in(strobe_hb1),.data_in(bb_q),.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(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(interp_rate),
.strobe_in(strobe_cic),.strobe_out(1),
.signal_in(hb2_q),.signal_out(q_interp));
assign strobe = strobe_hb1;
localparam cwidth = 24; // 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({{2{scale_i[15]}},scale_i}), // 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({{2{scale_q[15]}},scale_q}), // 18-bit multiplier input
.C(clk), // Clock input
.CE(1), // Clock enable input
.R(rst) // Synchronous reset input
);
always @(posedge clk)
case(dacmux_a)
0 : dac_a <= prod_i[28:13];
1 : dac_a <= prod_q[28:13];
default : dac_a <= 0;
endcase // case(dacmux_a)
always @(posedge clk)
case(dacmux_b)
0 : dac_b <= prod_i[28:13];
1 : dac_b <= prod_q[28:13];
default : dac_b <= 0;
endcase // case(dacmux_b)
assign debug = {strobe_cic, strobe_hb1, strobe_hb2,run};
endmodule // dsp_core
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