diff options
Diffstat (limited to 'fpga/usrp3/lib/dsp/duc_chain.v')
| -rw-r--r-- | fpga/usrp3/lib/dsp/duc_chain.v | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/fpga/usrp3/lib/dsp/duc_chain.v b/fpga/usrp3/lib/dsp/duc_chain.v new file mode 100644 index 000000000..06c87bd34 --- /dev/null +++ b/fpga/usrp3/lib/dsp/duc_chain.v @@ -0,0 +1,146 @@ +// +// Copyright 2011-2013 Ettus Research LLC +// + + +//! 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 |