Test with modem connected

Now talking over the bus instead of using dpram

.gitignore

@@ -1,2 +1,3 @@
 build/
 out/
+*__pycache__*

cores/primitive/lvds_comparator/lvds_comparator.core

@@ -0,0 +1,26 @@
+CAPI=2:
+
+name: joppeb:primitive:lvds_comparator:1.0
+description: LVDS comparator wrapper
+
+filesets:
+    wrapper:
+        files:
+            - lvds_comparator.v
+        file_type: verilogSource
+    generic:
+        files:
+            - lvds_comparator_generic_impl.v
+        file_type: verilogSource
+    spartan6:
+        files:
+            - lvds_comparator_spartan6.v
+        file_type: verilogSource
+
+targets:
+    default:
+        filesets:
+            - wrapper
+            - generic
+            - spartan6
+        toplevel: lvds_comparator

cores/primitive/lvds_comparator/lvds_comparator.v

@@ -0,0 +1,19 @@
+module lvds_comparator(
+    input wire a,
+    input wire b,
+    output wire o
+);
+`ifdef FPGA_SPARTAN6
+    lvds_comparator_spartan6_impl impl_i (
+        .a(a),
+        .b(b),
+        .o(o)
+    );
+`else
+    lvds_comparator_generic_impl impl_i (
+        .a(a),
+        .b(b),
+        .o(o)
+    );
+`endif
+endmodule

cores/primitive/lvds_comparator/lvds_comparator_generic_impl.v

@@ -0,0 +1,7 @@
+module lvds_comparator_generic_impl (
+    input wire a,
+    input wire b,
+    output wire o
+);
+    assign o = a;
+endmodule

cores/primitive/lvds_comparator/lvds_comparator_spartan6.v

@@ -0,0 +1,14 @@
+module lvds_comparator_spartan6_impl (
+    input wire a,
+    input wire b,
+    output wire o
+);
+    IBUFDS #(
+        .DIFF_TERM("FALSE"),
+        .IOSTANDARD("LVDS_33")
+    ) lvds_buf (
+        .O(o),
+        .I(a),
+        .IB(b)
+    );
+endmodule

cores/signal/decimate_by_r_q15.v/decimate_by_r_q15.core

@@ -0,0 +1,29 @@
+CAPI=2:
+
+name: joppeb:signal:decimate_by_r_q15:1.0
+description: Q1.15 integer-rate decimator
+
+filesets:
+    rtl:
+        files:
+            - decimate_by_r_q15.v
+        file_type: verilogSource
+
+targets:
+    default:
+        filesets:
+            - rtl
+        toplevel: decimate_by_r_q15
+        parameters:
+            - R
+            - CNT_W
+
+parameters:
+    R:
+        datatype: int
+        description: Integer decimation ratio
+        paramtype: vlogparam
+    CNT_W:
+        datatype: int
+        description: Counter width for the decimation counter
+        paramtype: vlogparam

cores/signal/decimate_by_r_q15.v/decimate_by_r_q15.v

@@ -0,0 +1,74 @@
+`timescale 1ns/1ps
+
+// =============================================================================
+// Decimator by R
+// Reduces the effective sample rate by an integer factor R by selecting every
+// R-th input sample. Generates a one-cycle 'o_valid' pulse each time a new
+// decimated sample is produced.
+//
+// Implements:
+//      For each valid input sample:
+//          if (count == R-1):
+//              count     <= 0
+//              o_q15   <= i_q15
+//              o_valid <= 1
+//          else:
+//              count     <= count + 1
+//
+// parameters:
+//      -- R      : integer decimation factor (e.g., 400)
+//                   output sample rate = input rate / R
+//      -- CNT_W  : counter bit width, must satisfy 2^CNT_W > R
+//
+// inout:
+//      -- i_clk     : input clock (same rate as 'i_valid')
+//      -- i_rst_n   : active-low synchronous reset
+//      -- i_valid   : input data strobe; assert 1'b1 if input is always valid
+//      -- i_q15     : signed 16-bit Q1.15 input sample (full-rate)
+//      -- o_valid   : single-cycle pulse every R samples (decimated rate strobe)
+//      -- o_q15     : signed 16-bit Q1.15 output sample (decimated stream)
+//
+// Notes:
+//  - This module performs *pure downsampling* (sample selection only).
+//    It does not include any anti-alias filtering; high-frequency content
+//    above the new Nyquist limit (Fs_out / 2) will alias into the baseband.
+//  - For most applications, an anti-alias low-pass filter such as
+//    lpf_iir_q15 or a FIR stage should precede this decimator.
+//  - The output sample rate is given by:
+//          Fs_out = Fs_in / R
+//  - Typical usage: interface between high-rate sigma-delta or oversampled
+//    data streams and lower-rate processing stages.
+// =============================================================================
+module decimate_by_r_q15 #(
+    parameter integer R      = 400, // decimation factor
+    parameter integer CNT_W  = 10   // width so that 2^CNT_W > R (e.g., 10 for 750)
+)(
+    input  wire        i_clk,
+    input  wire        i_rst_n,
+    input  wire        i_valid,          // assert 1'b1 if always valid
+    input  wire signed [15:0] i_q15,     // Q1.15 sample at full rate
+    output reg         o_valid,          // 1-cycle pulse every R samples
+    output reg  signed [15:0] o_q15      // Q1.15 sample at decimated rate
+);
+    reg [CNT_W-1:0] cnt;
+
+    always @(posedge i_clk or negedge i_rst_n) begin
+        if (!i_rst_n) begin
+            cnt       <= {CNT_W{1'b0}};
+            o_valid   <= 1'b0;
+            o_q15     <= 16'sd0;
+        end else begin
+            o_valid <= 1'b0;
+
+            if (i_valid) begin
+                if (cnt == R-1) begin
+                    cnt       <= {CNT_W{1'b0}};
+                    o_q15     <= i_q15;
+                    o_valid   <= 1'b1;
+                end else begin
+                    cnt <= cnt + 1'b1;
+                end
+            end
+        end
+    end
+endmodule

cores/signal/lpf_iir_q15_k/lpf_iir_q15_k.core

@@ -0,0 +1,24 @@
+CAPI=2:
+
+name: joppeb:signal:lpf_iir_q15_k:1.0
+description: First-order Q1.15 IIR low-pass filter
+
+filesets:
+    rtl:
+        files:
+            - lpf_iir_q15_k.v
+        file_type: verilogSource
+
+targets:
+    default:
+        filesets:
+            - rtl
+        toplevel: lpf_iir_q15_k
+        parameters:
+            - K
+
+parameters:
+    K:
+        datatype: int
+        description: Filter shift factor
+        paramtype: vlogparam

cores/signal/lpf_iir_q15_k/lpf_iir_q15_k.v

@@ -0,0 +1,64 @@
+`timescale 1ns/1ps
+
+// =============================================================================
+// Low-Pass IIR Filter (Q1.15)
+// Simple first-order infinite impulse response filter, equivalent to an
+// exponential moving average. Provides an adjustable smoothing factor based
+// on parameter K.
+//
+// Implements:
+//      Y[n+1] = Y[n] + (X[n] - Y[n]) / 2^K
+//
+// This is a purely digital one-pole low-pass filter whose time constant
+// approximates that of an analog RC filter, where alpha = 1 / 2^K.
+//
+// The larger K is, the slower the filter responds (stronger smoothing).
+// The smaller K is, the faster it reacts to changes.
+//
+// parameters:
+//      -- K : filter shift factor (integer, 4..14 typical)
+//              cutoff frequency ≈ Fs / (2π * 2^K)
+//              larger K → lower cutoff
+//
+// inout:
+//      -- i_clk   : input clock
+//      -- i_rst_n : active-low reset
+//      -- i_x_q15 : signed 16-bit Q1.15 input sample (e.g., 0..0x7FFF)
+//      -- o_y_q15 : signed 16-bit Q1.15 filtered output
+//
+// Notes:
+//  - The arithmetic right shift implements division by 2^K.
+//  - Internal arithmetic is Q1.15 fixed-point with saturation
+//    to [0, 0x7FFF] (for non-negative signals).
+//  - Useful for smoothing noisy ADC / sigma-delta data streams
+//    or modeling an RC envelope follower.
+// =============================================================================
+module lpf_iir_q15_k #( 
+    parameter integer K = 10 // try 8..12; bigger = more smoothing 
+)( 
+    input wire i_clk, 
+    input wire i_rst_n, 
+    input wire signed [15:0] i_x_q15, // Q1.15 input (e.g., 0..0x7FFF) 
+    output reg signed [15:0] o_y_q15 // Q1.15 output 
+); 
+    wire signed [15:0] e_q15 = i_x_q15 - o_y_q15; 
+    wire signed [15:0] delta_q15 = e_q15 >>> K; // arithmetic shift 
+    wire signed [15:0] y_next = o_y_q15 + delta_q15; // clamp to [0, 0x7FFF] (handy if your signal is non-negative) 
+    
+    function signed [15:0] clamp01; 
+        input signed [15:0] v; 
+    begin
+        if (v < 16'sd0) 
+            clamp01 = 16'sd0; 
+        else if (v > 16'sh7FFF) 
+            clamp01 = 16'sh7FFF; 
+        else 
+            clamp01 = v; 
+        end 
+    endfunction 
+    
+    always @(posedge i_clk or negedge i_rst_n) begin 
+        if (!i_rst_n) o_y_q15 <= 16'sd0; 
+        else o_y_q15 <= clamp01(y_next); 
+    end 
+endmodule

cores/signal/nco_q15/rtl/nco_q15.v

@@ -8,23 +8,23 @@
 //      -- CLK_HZ : input clock frequency in Hz
 //      -- FS_HZ : output sample frequency in Hz
 // inout:
-//      -- clk : input clock
+//      -- i_clk : input clock
-//      -- rst_n : reset
+//      -- i_rst_n : reset
-//      -- freq_hz : decimal number of desired generated frequency in Hz, 0-FS/2
+//      -- i_freq_hz : decimal number of desired generated frequency in Hz, 0-FS/2
-//      -- sin_q15/cos_q15 : I and Q outputs
+//      -- o_sin_q15/o_cos_q15 : I and Q outputs
-//      -- clk_en : output valid strobe
+//      -- o_clk_en : output valid strobe
 // =============================================================================
 module nco_q15 #(
     parameter integer CLK_HZ = 120_000_000,         // input clock
     parameter integer FS_HZ = 40_000                // sample rate
 )(
-    input wire clk,                                 // CLK_HZ domain
+    input wire i_clk,                               // CLK_HZ domain
-    input wire rst_n,                               // async active-low reset
+    input wire i_rst_n,                             // async active-low reset
-    input wire [31:0] freq_hz,                      // desired output frequency (Hz), 0..FS_HZ/2
+    input wire [31:0] i_freq_hz,                    // desired output frequency (Hz), 0..FS_HZ/2
 
-    output reg signed [15:0] sin_q15,               // Q1.15 sine
+    output reg signed [15:0] o_sin_q15,             // Q1.15 sine
-    output reg signed [15:0] cos_q15,               // Q1.15 cosine
+    output reg signed [15:0] o_cos_q15,             // Q1.15 cosine
-    output reg clk_en                               // 1-cycle strobe @ FS_HZ
+    output reg o_clk_en                             // 1-cycle strobe @ FS_HZ
 );
     localparam integer PHASE_FRAC_BITS = 6;
     localparam integer QTR_ADDR_BITS = 6;
@@ -41,17 +41,17 @@ module nco_q15 #(
     endfunction
 
     reg [clog2(DIV)-1:0] tick_cnt;
-    always @(posedge clk or negedge rst_n) begin
+    always @(posedge i_clk or negedge i_rst_n) begin
-        if (!rst_n) begin tick_cnt <= 0; clk_en <= 1'b0; end
+        if (!i_rst_n) begin tick_cnt <= 0; o_clk_en <= 1'b0; end
         else begin
-        clk_en <= 1'b0;
+        o_clk_en <= 1'b0;
-        if (tick_cnt == DIV-1) begin tick_cnt <= 0; clk_en <= 1'b1; end
+        if (tick_cnt == DIV-1) begin tick_cnt <= 0; o_clk_en <= 1'b1; end
         else tick_cnt <= tick_cnt + 1'b1;
         end
     end
 
-    // 32-cycle shift-add multiply: prod = freq_hz * RECIP  (no multiplications themself)
+    // 32-cycle shift-add multiply: prod = i_freq_hz * RECIP  (no multiplications themself)
-	// Starts at clk_en, finishes in 32 cycles (<< available cycles per sample).
+	// Starts at o_clk_en, finishes in 32 cycles (<< available cycles per sample).
     reg        mul_busy;
     reg  [5:0] mul_i;           // 0..31
     reg [31:0] f_reg;
@@ -59,15 +59,15 @@ module nco_q15 #(
 
     wire [95:0] recip_shift = {{32{1'b0}}, RECIP} << mul_i; // shift constant by i
 
-    always @(posedge clk or negedge rst_n) begin
+    always @(posedge i_clk or negedge i_rst_n) begin
-        if (!rst_n) begin
+        if (!i_rst_n) begin
         mul_busy <= 1'b0; mul_i <= 6'd0; f_reg <= 32'd0; acc <= 96'd0;
         end else begin
-        if (clk_en && !mul_busy) begin
+        if (o_clk_en && !mul_busy) begin
             // kick off a new multiply this sample
             mul_busy <= 1'b1;
             mul_i    <= 6'd0;
-            f_reg    <= (freq_hz > (FS_HZ>>1)) ? (FS_HZ>>1) : freq_hz; // clamp to Nyquist
+            f_reg    <= (i_freq_hz > (FS_HZ>>1)) ? (FS_HZ>>1) : i_freq_hz; // clamp to Nyquist
             acc      <= 96'd0;
         end else if (mul_busy) begin
             // add shifted RECIP if bit is set
@@ -86,16 +86,16 @@ module nco_q15 #(
     wire [95:0] acc_round = acc + (96'd1 << (SHIFT-1));
     wire [PHASE_BITS-1:0] ftw_next = acc_round[SHIFT +: PHASE_BITS]; // >> SHIFT
 
-    always @(posedge clk or negedge rst_n) begin
+    always @(posedge i_clk or negedge i_rst_n) begin
-        if (!rst_n) ftw_q <= {PHASE_BITS{1'b0}};
+        if (!i_rst_n) ftw_q <= {PHASE_BITS{1'b0}};
         else if (!mul_busy) ftw_q <= ftw_next; // update once product ready
     end
 
     // Phase accumulator (advance at FS_HZ)
     reg [PHASE_BITS-1:0] phase;
-    always @(posedge clk or negedge rst_n) begin
+    always @(posedge i_clk or negedge i_rst_n) begin
-        if (!rst_n)      phase <= {PHASE_BITS{1'b0}};
+        if (!i_rst_n)        phase <= {PHASE_BITS{1'b0}};
-        else if (clk_en) phase <= phase + ftw_q;
+        else if (o_clk_en) phase <= phase + ftw_q;
     end
 
     // Cosine phase = sine phase + 90°
@@ -113,8 +113,8 @@ module nco_q15 #(
 
     // 64-entry quarter-wave LUT
     wire [7:0] mag_sin_u8, mag_cos_u8;
-    sine_qtr_lut64 u_lut_s (.addr(idx_sin), .dout(mag_sin_u8));
+    sine_qtr_lut64 u_lut_s (.i_addr(idx_sin), .o_dout(mag_sin_u8));
-    sine_qtr_lut64 u_lut_c (.addr(idx_cos), .dout(mag_cos_u8));
+    sine_qtr_lut64 u_lut_c (.i_addr(idx_cos), .o_dout(mag_cos_u8));
 
     // Scale to Q1.15 and apply sign
     wire signed [15:0] mag_sin_q15 = {1'b0, mag_sin_u8, 7'd0};
@@ -125,39 +125,39 @@ module nco_q15 #(
     wire signed [15:0] sin_next = sin_neg ? -mag_sin_q15 : mag_sin_q15;
     wire signed [15:0] cos_next = cos_neg ? -mag_cos_q15 : mag_cos_q15;
 
-    always @(posedge clk or negedge rst_n) begin
+    always @(posedge i_clk or negedge i_rst_n) begin
-        if (!rst_n) begin
+        if (!i_rst_n) begin
-        sin_q15 <= 16'sd0; cos_q15 <= 16'sd0;
+        o_sin_q15 <= 16'sd0; o_cos_q15 <= 16'sd0;
-        end else if (clk_en) begin
+        end else if (o_clk_en) begin
-        sin_q15 <= sin_next; cos_q15 <= cos_next;
+        o_sin_q15 <= sin_next; o_cos_q15 <= cos_next;
         end
     end
 
 endmodule
 	
 module sine_qtr_lut64(
-    input wire [5:0] addr,
+    input wire [5:0] i_addr,
-    output reg [7:0] dout
+    output reg [7:0] o_dout
 );
     always @* begin
-        case (addr)
+        case (i_addr)
-            6'd0: dout = 8'd0;    6'd1: dout = 8'd6;    6'd2: dout = 8'd13;   6'd3: dout = 8'd19;
+            6'd0: o_dout = 8'd0;    6'd1: o_dout = 8'd6;    6'd2: o_dout = 8'd13;   6'd3: o_dout = 8'd19;
-            6'd4: dout = 8'd25;   6'd5: dout = 8'd31;   6'd6: dout = 8'd37;   6'd7: dout = 8'd44;
+            6'd4: o_dout = 8'd25;   6'd5: o_dout = 8'd31;   6'd6: o_dout = 8'd37;   6'd7: o_dout = 8'd44;
-            6'd8: dout = 8'd50;   6'd9: dout = 8'd56;   6'd10: dout = 8'd62;  6'd11: dout = 8'd68;
+            6'd8: o_dout = 8'd50;   6'd9: o_dout = 8'd56;   6'd10: o_dout = 8'd62;  6'd11: o_dout = 8'd68;
-            6'd12: dout = 8'd74;  6'd13: dout = 8'd80;  6'd14: dout = 8'd86;  6'd15: dout = 8'd92;
+            6'd12: o_dout = 8'd74;  6'd13: o_dout = 8'd80;  6'd14: o_dout = 8'd86;  6'd15: o_dout = 8'd92;
-            6'd16: dout = 8'd98;  6'd17: dout = 8'd103; 6'd18: dout = 8'd109; 6'd19: dout = 8'd115;
+            6'd16: o_dout = 8'd98;  6'd17: o_dout = 8'd103; 6'd18: o_dout = 8'd109; 6'd19: o_dout = 8'd115;
-            6'd20: dout = 8'd120; 6'd21: dout = 8'd126; 6'd22: dout = 8'd131; 6'd23: dout = 8'd136;
+            6'd20: o_dout = 8'd120; 6'd21: o_dout = 8'd126; 6'd22: o_dout = 8'd131; 6'd23: o_dout = 8'd136;
-            6'd24: dout = 8'd142; 6'd25: dout = 8'd147; 6'd26: dout = 8'd152; 6'd27: dout = 8'd157;
+            6'd24: o_dout = 8'd142; 6'd25: o_dout = 8'd147; 6'd26: o_dout = 8'd152; 6'd27: o_dout = 8'd157;
-            6'd28: dout = 8'd162; 6'd29: dout = 8'd167; 6'd30: dout = 8'd171; 6'd31: dout = 8'd176;
+            6'd28: o_dout = 8'd162; 6'd29: o_dout = 8'd167; 6'd30: o_dout = 8'd171; 6'd31: o_dout = 8'd176;
-            6'd32: dout = 8'd180; 6'd33: dout = 8'd185; 6'd34: dout = 8'd189; 6'd35: dout = 8'd193;
+            6'd32: o_dout = 8'd180; 6'd33: o_dout = 8'd185; 6'd34: o_dout = 8'd189; 6'd35: o_dout = 8'd193;
-            6'd36: dout = 8'd197; 6'd37: dout = 8'd201; 6'd38: dout = 8'd205; 6'd39: dout = 8'd208;
+            6'd36: o_dout = 8'd197; 6'd37: o_dout = 8'd201; 6'd38: o_dout = 8'd205; 6'd39: o_dout = 8'd208;
-            6'd40: dout = 8'd212; 6'd41: dout = 8'd215; 6'd42: dout = 8'd219; 6'd43: dout = 8'd222;
+            6'd40: o_dout = 8'd212; 6'd41: o_dout = 8'd215; 6'd42: o_dout = 8'd219; 6'd43: o_dout = 8'd222;
-            6'd44: dout = 8'd225; 6'd45: dout = 8'd228; 6'd46: dout = 8'd231; 6'd47: dout = 8'd233;
+            6'd44: o_dout = 8'd225; 6'd45: o_dout = 8'd228; 6'd46: o_dout = 8'd231; 6'd47: o_dout = 8'd233;
-            6'd48: dout = 8'd236; 6'd49: dout = 8'd238; 6'd50: dout = 8'd240; 6'd51: dout = 8'd242;
+            6'd48: o_dout = 8'd236; 6'd49: o_dout = 8'd238; 6'd50: o_dout = 8'd240; 6'd51: o_dout = 8'd242;
-            6'd52: dout = 8'd244; 6'd53: dout = 8'd246; 6'd54: dout = 8'd247; 6'd55: dout = 8'd249;
+            6'd52: o_dout = 8'd244; 6'd53: o_dout = 8'd246; 6'd54: o_dout = 8'd247; 6'd55: o_dout = 8'd249;
-            6'd56: dout = 8'd250; 6'd57: dout = 8'd251; 6'd58: dout = 8'd252; 6'd59: dout = 8'd253;
+            6'd56: o_dout = 8'd250; 6'd57: o_dout = 8'd251; 6'd58: o_dout = 8'd252; 6'd59: o_dout = 8'd253;
-            6'd60: dout = 8'd254; 6'd61: dout = 8'd254; 6'd62: dout = 8'd255; 6'd63: dout = 8'd255;
+            6'd60: o_dout = 8'd254; 6'd61: o_dout = 8'd254; 6'd62: o_dout = 8'd255; 6'd63: o_dout = 8'd255;
-            default: dout=8'd0;
+            default: o_dout=8'd0;
         endcase
     end
-endmodule
+endmodule

cores/signal/nco_q15/tb/tb_nco_q15.v

@@ -15,12 +15,12 @@ module tb_nco_q15();
     wire out_en;
 
     nco_q15 #(.CLK_HZ(120_000_000), .FS_HZ(40_000)) nco (
-        .clk    (clk),
+        .i_clk    (clk),
-        .rst_n  (resetn),
+        .i_rst_n  (resetn),
-        .freq_hz(freq),
+        .i_freq_hz(freq),
-        .sin_q15(sin_q15),
+        .o_sin_q15(sin_q15),
-        .cos_q15(cos_q15),
+        .o_cos_q15(cos_q15),
-        .clk_en (out_en)
+        .o_clk_en (out_en)
     );
 
     initial begin
@@ -39,4 +39,4 @@ module tb_nco_q15();
         $finish;
     end;
 
-endmodule
+endmodule

cores/signal/sd_adc_q15/rtl/rc_alpha_q15.vh

@@ -0,0 +1,91 @@
+// rc_alpha_q15.vh
+// Plain Verilog-2001 constant function: R(ohm), C(pF), Fs(Hz) -> alpha_q15 (Q1.15)
+// Uses fixed-point approximation: 1 - exp(-x) ≈ x - x^2/2 + x^3/6, where x = 1/(Fs*R*C)
+// All integer math; suitable for elaboration-time constant folding (e.g., XST).
+
+`ifndef RC_ALPHA_Q15_VH
+`define RC_ALPHA_Q15_VH
+
+function integer alpha_q15_from_rc;
+    input integer R_OHM; // ohms
+    input integer C_PF;  // picofarads
+    input integer FS_HZ; // Hz
+
+    // Choose QN for x. N=24 is a good balance for accuracy/width.
+    integer N;
+
+    // We'll keep everything as unsigned vectors; inputs copied into vectors first.
+    reg [63:0] R_u, C_u, FS_u;
+
+    // x = 1 / (Fs * R * C) with C in pF -> x = 1e12 / (Fs*R*C_pf)
+    // x_qN = round( x * 2^N ) = round( (1e12 << N) / denom )
+    reg  [127:0] NUM_1E12_SLLN;  // big enough for 1e12 << N
+    reg  [127:0] DENOM;          // Fs*R*C
+    reg  [127:0] X_qN;           // x in QN
+
+    // Powers
+    reg  [255:0] X2;             // x^2 in Q(2N)
+    reg  [383:0] X3;             // x^3 in Q(3N)
+
+    integer term1_q15;
+    integer term2_q15;
+    integer term3_q15;
+    integer acc;
+
+begin
+    N = 24;
+
+    // Copy integer inputs into 64-bit vectors (no bit-slicing of integers)
+    R_u  = R_OHM[31:0];
+    C_u  = C_PF[31:0];
+    FS_u = FS_HZ[31:0];
+
+    // Denominator = Fs * R * C_pf  (fits in < 2^64 for typical values)
+    DENOM = 128'd0;
+    DENOM = FS_u;
+    DENOM = DENOM * R_u;
+    DENOM = DENOM * C_u;
+
+    // // Guard: avoid divide by zero
+    // if (DENOM == 0) begin
+    //     alpha_q15_from_rc = 0;
+    //     disable alpha_q15_from_rc;
+    // end
+
+    // Numerator = (1e12 << N). 1e12 * 2^24 ≈ 1.6777e19 (fits in 2^64..2^65),
+    // so use 128 bits to be safe.
+    NUM_1E12_SLLN = 128'd1000000000000 << N;
+
+    // x_qN = rounded division
+    X_qN = (NUM_1E12_SLLN + (DENOM >> 1)) / DENOM;
+
+    // Powers
+    X2 = X_qN * X_qN;
+    X3 = X2 * X_qN;
+
+    // Convert terms to Q1.15:
+    // term1 = x            -> shift from QN to Q15
+    term1_q15 = (X_qN >> (N - 15)) & 16'hFFFF;
+
+    // term2 = x^2 / 2      -> Q(2N) to Q15 and /2
+    term2_q15 = (X2 >> (2*N - 15 + 1)) & 16'hFFFF;
+
+    // term3 = x^3 / 6      -> Q(3N) to Q15, then /6 with rounding
+    begin : gen_t3
+        reg [383:0] tmp_q15_wide;
+        reg [383:0] tmp_div6;
+        tmp_q15_wide = (X3 >> (3*N - 15));
+        tmp_div6     = (tmp_q15_wide + 6'd3) / 6;
+        term3_q15    = tmp_div6[15:0];
+    end
+
+    // Combine and clamp
+    acc = term1_q15 - term2_q15 + term3_q15;
+    if (acc < 0)            acc = 0;
+    else if (acc > 16'h7FFF) acc = 16'h7FFF;
+
+    alpha_q15_from_rc = acc;
+end
+endfunction
+
+`endif

cores/signal/sd_adc_q15/rtl/rcmodel_q15.v

@@ -0,0 +1,55 @@
+`timescale 1ns/1ps
+
+// =============================================================================
+// RC model to convert sigma delta samples to Q1.15
+// Models the RC circuit on the outside of the FPGA
+// Uses: Yn+1 = Yn + (sd - Yn)*(1-exp(-T/RC))
+// parameters:
+//      -- alpha_q15 : the 1-exp(-T/RC), defaults to R=3k3, C=220p and T=1/15MHz
+//							  rounded to only use two bits (0b3b -> 0b00), the less
+//							  bits the better
+// inout:
+//      -- i_clk : input clock
+//      -- i_rst_n : reset signal
+//      -- i_sd_sample : 1 bit sample output from sd sampler
+//      -- o_sample_q15 : output samples in q.15
+// =============================================================================
+module rcmodel_q15 #(
+    parameter integer alpha_q15 = 16'sh0b00
+)(
+    input wire i_clk,
+    input wire i_rst_n,
+    input wire i_sd_sample,
+    output wire [15:0] o_sample_q15
+);
+    reg signed [15:0] y_q15;
+    wire signed [15:0] sd_q15 = i_sd_sample ? 16'sh7fff : 16'sh0000;
+    wire signed [15:0] e_q15 = sd_q15 - y_q15;
+    // wire signed [31:0] prod_q30 = $signed(e_q15) * $signed(alpha_q15);
+    wire signed [31:0] prod_q30;
+    // Use shift-add algorithm for multiplication
+    mul_const_shiftadd #(
+        .C($signed(alpha_q15)),
+        .IN_W(16),
+        .OUT_W(32)
+    ) alpha_times_e (
+        .i_x(e_q15),
+        .o_y(prod_q30)
+    );
+    wire signed [15:0] y_next_q15 = y_q15 + (prod_q30>>>15);
+
+    // clamp to [0, 0x7FFF] (keeps signal view tidy)
+    function signed [15:0] clamp01_q15(input signed [15:0] v);
+        if (v < 16'sd0000) clamp01_q15 = 16'sd0000;
+        else if (v > 16'sh7FFF) clamp01_q15 = 16'sh7FFF;
+        else clamp01_q15 = v;
+    endfunction
+
+    always @(posedge i_clk or negedge i_rst_n) begin
+        if (!i_rst_n) y_q15 <= 16'sd0000;
+        else y_q15 <= clamp01_q15(y_next_q15);
+    end
+
+    assign o_sample_q15 = y_q15;
+
+endmodule

cores/signal/sd_adc_q15/rtl/sd_adc_q15.v

@@ -0,0 +1,58 @@
+module sd_adc_q15 #(
+    parameter integer R_OHM = 3300,
+    parameter integer C_PF = 220
+)(
+    input wire i_clk_15,
+    input wire i_rst_n,
+    
+    input wire i_adc_a,
+    input wire i_adc_b,
+    output wire o_adc,
+
+    output wire signed [15:0] o_signal_q15,
+    output wire o_signal_valid
+);
+    `include "rc_alpha_q15.vh"
+
+    wire sd_signal;
+    wire signed [15:0] raw_sample_biased;
+    wire signed [15:0] raw_sample_q15;
+    wire signed [15:0] lpf_sample_q15;
+
+    sd_sampler sd_sampler(
+        .i_clk(i_clk_15),
+        .i_a(i_adc_a), .i_b(i_adc_b),
+        .o_sample(sd_signal)
+    );
+    assign o_adc = sd_signal;
+
+    localparam integer alpha_q15_int = alpha_q15_from_rc(R_OHM, C_PF, 15000000);
+    localparam signed [15:0] alpha_q15 = alpha_q15_int[15:0];
+    localparam signed [15:0] alpha_q15_top = alpha_q15 & 16'hff00;
+    rcmodel_q15 #(
+        .alpha_q15(alpha_q15_top)
+    ) rc_model (
+        .i_clk(i_clk_15), .i_rst_n(i_rst_n),
+        .i_sd_sample(sd_signal),
+        .o_sample_q15(raw_sample_q15)
+    );
+
+    lpf_iir_q15_k #(
+        .K(8)
+    ) lpf (
+        .i_clk(i_clk_15), .i_rst_n(i_rst_n),
+        .i_x_q15(raw_sample_q15),
+        .o_y_q15(lpf_sample_q15)
+    );
+
+    decimate_by_r_q15 #(
+        // .R(200), // 15MHz/200 = 75KHz
+        .R(375), // 15MHz/375 = 40KHz
+        .CNT_W(10)
+    ) decimate (
+        .i_clk(i_clk_15), .i_rst_n(i_rst_n),
+        .i_valid(1'b1), .i_q15(lpf_sample_q15),
+        .o_valid(o_signal_valid), .o_q15(o_signal_q15)
+    );
+
+endmodule

cores/signal/sd_adc_q15/rtl/sd_sampler.v

@@ -0,0 +1,18 @@
+module sd_sampler(
+    input wire i_clk,
+    input wire i_a,
+    input wire i_b,
+    output wire o_sample
+);
+
+    wire comp_out;
+    lvds_comparator comp (
+        .a(i_a), .b(i_b), .o(comp_out)
+    );
+
+    reg registered_comp_out;
+    always @(posedge i_clk) 
+        registered_comp_out <= comp_out;
+    assign o_sample = registered_comp_out;
+
+endmodule

cores/signal/sd_adc_q15/sd_adc_q15.core

@@ -0,0 +1,57 @@
+CAPI=2:
+
+name: joppeb:signal:sd_adc_q15:1.0
+description: Sigma-delta ADC front-end with Q1.15 output
+
+filesets:
+    rtl_common:
+        depend:
+            - joppeb:primitive:lvds_comparator
+            - joppeb:signal:lpf_iir_q15_k
+            - joppeb:signal:decimate_by_r_q15
+            - joppeb:util:mul_const
+        files:
+            - rtl/rc_alpha_q15.vh:
+                is_include_file: true
+            - rtl/rcmodel_q15.v
+            - rtl/sd_adc_q15.v
+        file_type: verilogSource
+    rtl_sampler:
+        files:
+            - rtl/sd_sampler.v
+        file_type: verilogSource
+    sim_sampler:
+        files:
+            - sim/sd_sampler.v
+        file_type: verilogSource
+    tb:
+        files:
+            - tb/tb_sd_adc_q15.v
+        file_type: verilogSource
+
+targets:
+    default:
+        filesets:
+            - rtl_common
+            - rtl_sampler
+        toplevel: sd_adc_q15
+        parameters:
+            - R_OHM
+            - C_PF
+    sim:
+        default_tool: icarus
+        filesets:
+            - rtl_common
+            - sim_sampler
+            - tb
+        toplevel: tb_sd_adc_q15
+
+parameters:
+    R_OHM:
+        datatype: int
+        description: RC filter resistor value in ohms
+        paramtype: vlogparam
+    C_PF:
+        datatype: int
+        description: RC filter capacitor value in pF
+        paramtype: vlogparam

cores/signal/sd_adc_q15/sim/sd_sampler.v

@@ -0,0 +1,111 @@
+`timescale 1ns/1ps
+
+// =============================================================================
+// Sigma-Delta sampler
+// Simulates an RC circuit between o_sample and i_b and i_a sine at i_a
+// =============================================================================
+module sd_sampler(
+    input wire i_clk,
+    input wire i_a,
+    input wire i_b,
+    output wire o_sample
+);
+
+    // Sine source (i_a input / P)
+    parameter real    F_HZ       = 5000;   // input sine frequency (1 kHz)
+    parameter real    AMP        = 1.5;     // sine amplitude (V)
+    parameter real    VCM        = 1.65;    // common-mode (V), centered in 0..3.3V
+
+    // Comparator behavior
+    parameter real    VTH        = 0.0;     // threshold on (vp - vn)
+    parameter real    VHYST      = 0.05;     // symmetric hysteresis half-width (V)
+    parameter integer ADD_HYST   = 0;       // 1 to enable hysteresis
+
+    // 1-bit DAC rails (feedback into RC)
+    parameter real    VLOW       = 0.0;     // DAC 0 (V)
+    parameter real    VHIGH      = 3.3;     // DAC 1 (V)
+
+    // RC filter (i_b input / N)
+    parameter real    R_OHMS     = 3300.0;  // 3.3k
+    parameter real    C_FARADS   = 220e-12; // 220 pF
+
+    // Integration step (ties to `timescale`)
+    parameter integer TSTEP_NS   = 10;      // sim step in ns (choose << tau)
+
+    // ===== Internal state (simulation only) =====
+    real vp, vn;          // comparator i_a/i_b inputs
+    real v_rc;            // RC node voltage (== vn)
+    real v_dac;           // DAC output voltage from o_sample
+    real t_s;             // time in seconds
+    real dt_s;            // step in seconds
+    real tau_s;           // R*C time constant in seconds
+    real two_pi;
+    reg  q;               // comparator latched output (pre-delay)
+    reg  out;
+    reg  sampler;
+
+    initial sampler <= 1'b0;
+    always @(posedge i_clk) begin
+        sampler <= out;
+    end
+    assign o_sample = sampler;
+
+
+    // Helper task: update comparator with optional hysteresis
+    task automatic comp_update;
+        real diff;
+    begin
+        diff = (vp - vn);
+
+        if (ADD_HYST != 0) begin
+            // simple symmetric hysteresis around VTH
+            if (q && (diff < (VTH - VHYST))) q = 1'b0;
+            else if (!q && (diff > (VTH + VHYST))) q = 1'b1;
+            // else hold
+        end else begin
+            q = (diff > VTH) ? 1'b1 : 1'b0;
+        end
+    end
+    endtask
+
+    initial begin
+        // Init constants
+        two_pi = 6.283185307179586;
+        tau_s  = R_OHMS * C_FARADS;       // ~7.26e-7 s
+        dt_s   = TSTEP_NS * 1.0e-9;
+
+        // Init states
+        t_s  = 0.0;
+        q    = 1'b0;                      // start low
+        out  = 1'b0;
+        v_dac= VLOW;
+        v_rc = (VHIGH + VLOW)/2.0;        // start mid-rail to reduce start-up transient
+        vn   = v_rc;
+        vp   = VCM;
+
+        // Main sim loop
+        forever begin
+            #(TSTEP_NS);                  // advance discrete time step
+            t_s  = t_s + dt_s;
+
+            // 1) Update DAC from previous comparator state
+            v_dac = sampler ? VHIGH : VLOW;
+
+            // 2) RC low-pass driven by DAC: Euler step
+            //    dv = (v_dac - v_rc) * dt/tau
+            v_rc  = v_rc + (v_dac - v_rc) * (dt_s / tau_s);
+            vn    = v_rc;
+
+            // 3) Input sine on i_a
+            vp    = VCM + AMP * $sin(two_pi * F_HZ * t_s);
+
+            // 4) Comparator decision (with optional hysteresis)
+            comp_update();
+
+            // 5) Output with propagation delay
+            out = q;
+        end
+    end
+
+
+endmodule

cores/signal/sd_adc_q15/tb/tb_sd_adc_q15.v

@@ -0,0 +1,36 @@
+`timescale 1ns/1ps
+
+module tb_sd_adc_q15();
+    // Clock and reset generation
+    reg clk;
+    reg resetn;
+    initial clk <= 1'b0;
+    initial resetn <= 1'b0;
+    always #6.667 clk <= !clk;
+    initial #40 resetn <= 1'b1;
+
+    // Default run
+    initial begin
+        $dumpfile("out.vcd");
+        $dumpvars;
+        #2_000_000
+        $finish;
+    end;
+
+    wire sd_a;
+    wire sd_b;
+    wire sd_o;
+    wire signed [15:0] decimated_q15;
+    wire decimated_valid;
+
+    sd_adc_q15 #(
+        .R_OHM(3300),
+        .C_PF(220)
+    ) dut(
+        .i_clk_15(clk), .i_rst_n(resetn),
+        .i_adc_a(sd_a), .i_adc_b(sd_b), .o_adc(sd_o),
+        .o_signal_q15(decimated_q15),
+        .o_signal_valid(decimated_valid)
+    );
+
+endmodule

cores/signal/signal_scope/rtl/signal_scope_q15.v

@@ -0,0 +1,257 @@
+`include "clog2.vh"
+
+module signal_scope_q15 #(
+    parameter depth = 2**12,
+    parameter chain = 1
+)(
+    input wire i_clk,
+    input wire i_rst,
+    input wire [15:0] i_signal_a,
+    input wire i_signal_valid_a,
+    input wire [15:0] i_signal_b,
+    input wire i_signal_valid_b,
+    input wire [15:0] i_signal_c,
+    input wire i_signal_valid_c,
+    input wire [15:0] i_signal_d,
+    input wire i_signal_valid_d
+);
+    localparam aw = `CLOG2(depth);
+    localparam [aw-1:0] depth_last = depth-1;
+    localparam [31:0] reg_base_addr = 32'h8000_0000;
+    localparam [3:0] reg_control = 4'h0;
+    localparam [3:0] reg_status = 4'h1;
+    localparam [3:0] reg_trig_val = 4'h2;
+
+    (* ram_style = "block" *) reg [16*4-1:0] mem[depth-1:0];
+    reg [aw-1:0] counter;
+    reg count_enable;
+    reg arm_req;
+    reg trigger_enable;
+    reg scope_armed;
+    reg scope_triggered;
+    reg capture_done;
+    reg [1:0] trigger_channel;
+    reg [15:0] trig_val;
+    reg [15:0] trigger_prev;
+    reg trigger_prev_valid;
+
+    reg [15:0] signal_a;
+    reg [15:0] signal_b;
+    reg [15:0] signal_c;
+    reg [15:0] signal_d;
+    reg signal_a_pending;
+    reg signal_b_pending;
+    reg signal_c_pending;
+    reg signal_d_pending;
+
+    wire [31:0] wb_adr;
+    wire [31:0] wb_dat;
+    wire [3:0] wb_sel;
+    wire wb_we;
+    wire wb_cyc;
+    wire wb_stb;
+    reg [31:0] wb_rdt;
+    reg wb_ack;
+    wire [aw-1:0] wb_mem_idx = wb_adr[aw+2:3];
+    wire wb_is_reg = (wb_adr[31:28] == reg_base_addr[31:28]);
+    wire [3:0] wb_reg_idx = wb_adr[5:2];
+    reg [15:0] trigger_sample;
+    reg trigger_sample_valid;
+    reg wb_mem_read_pending;
+    reg wb_mem_read_half;
+    reg wb_mem_read_oob;
+    reg [16*4-1:0] wb_mem_rdata;
+
+    jtag_wb_bridge #(
+        .chain(chain),
+        .byte_aligned(0)
+    ) jtag_scope_bridge (
+        .i_clk(i_clk),
+        .i_rst(i_rst),
+        .o_wb_adr(wb_adr),
+        .o_wb_dat(wb_dat),
+        .o_wb_sel(wb_sel),
+        .o_wb_we(wb_we),
+        .o_wb_cyc(wb_cyc),
+        .o_wb_stb(wb_stb),
+        .i_wb_rdt(wb_rdt),
+        .i_wb_ack(wb_ack),
+        .o_cmd_reset()
+    );
+
+    always @(*) begin
+        case(trigger_channel)
+            2'd0: begin
+                trigger_sample = i_signal_a;
+                trigger_sample_valid = i_signal_valid_a;
+            end
+            2'd1: begin
+                trigger_sample = i_signal_b;
+                trigger_sample_valid = i_signal_valid_b;
+            end
+            2'd2: begin
+                trigger_sample = i_signal_c;
+                trigger_sample_valid = i_signal_valid_c;
+            end
+            default: begin
+                trigger_sample = i_signal_d;
+                trigger_sample_valid = i_signal_valid_d;
+            end
+        endcase
+    end
+
+    always @(posedge i_clk) begin
+        if(i_rst) begin
+            counter <= {aw{1'b0}};
+            count_enable <= 1'b0;
+            arm_req <= 1'b0;
+            trigger_enable <= 1'b0;
+            scope_armed <= 1'b0;
+            scope_triggered <= 1'b0;
+            capture_done <= 1'b0;
+            trigger_channel <= 2'd0;
+            wb_ack <= 1'b0;
+            wb_rdt <= 32'b0;
+            trig_val <= 16'h0000;
+            trigger_prev <= 16'h0000;
+            trigger_prev_valid <= 1'b0;
+            signal_a <= 0;
+            signal_b <= 0;
+            signal_c <= 0;
+            signal_d <= 0;
+            signal_a_pending <= 1'b0;
+            signal_b_pending <= 1'b0;
+            signal_c_pending <= 1'b0;
+            signal_d_pending <= 1'b0;
+            wb_mem_read_pending <= 1'b0;
+            wb_mem_read_half <= 1'b0;
+            wb_mem_read_oob <= 1'b0;
+            wb_mem_rdata <= {(16*4){1'b0}};
+        end else begin
+
+            // Sample signals
+            if(i_signal_valid_a) begin
+                signal_a <= i_signal_a;
+                signal_a_pending <= 1'b1;
+            end
+            if(i_signal_valid_b) begin
+                signal_b <= i_signal_b;
+                signal_b_pending <= 1'b1;
+            end
+            if(i_signal_valid_c) begin
+                signal_c <= i_signal_c;
+                signal_c_pending <= 1'b1;
+            end
+            if(i_signal_valid_d) begin
+                signal_d <= i_signal_d;
+                signal_d_pending <= 1'b1;
+            end
+
+            // Trigger on selected channel rising across trig_val.
+            if(scope_armed && trigger_enable && !count_enable && trigger_sample_valid) begin
+                if(trigger_prev_valid &&
+                   ($signed(trigger_prev) < $signed(trig_val)) &&
+                   ($signed(trigger_sample) >= $signed(trig_val))) begin
+                    count_enable <= 1'b1;
+                    scope_triggered <= 1'b1;
+                end
+                trigger_prev <= trigger_sample;
+                trigger_prev_valid <= 1'b1;
+            end
+
+            // Arm/rearm capture. If trigger is disabled, start capture immediately.
+            if(arm_req) begin
+                counter <= {aw{1'b0}};
+                count_enable <= !trigger_enable;
+                scope_armed <= 1'b1;
+                scope_triggered <= !trigger_enable;
+                capture_done <= 1'b0;
+                trigger_prev_valid <= 1'b0;
+                signal_a_pending <= 1'b0;
+                signal_b_pending <= 1'b0;
+                signal_c_pending <= 1'b0;
+                signal_d_pending <= 1'b0;
+            end
+
+            // Write one full 4-channel frame at a time for maximum BRAM throughput.
+            if(count_enable && signal_a_pending && signal_b_pending && signal_c_pending && signal_d_pending) begin
+                if(counter <= depth_last) begin
+                    mem[counter] <= {signal_a, signal_b, signal_c, signal_d};
+                    counter <= counter + {{(aw-1){1'b0}}, 1'b1};
+                    if(counter == depth_last) begin
+                        count_enable <= 1'b0;
+                        scope_armed <= 1'b0;
+                        capture_done <= 1'b1;
+                    end
+                end else begin
+                    count_enable <= 1'b0;
+                    scope_armed <= 1'b0;
+                    capture_done <= 1'b1;
+                end
+                signal_a_pending <= 1'b0;
+                signal_b_pending <= 1'b0;
+                signal_c_pending <= 1'b0;
+                signal_d_pending <= 1'b0;
+            end
+
+            // WB slave response: register window + capture memory window.
+            arm_req <= 1'b0;
+            wb_ack <= 1'b0;
+
+            if(wb_mem_read_pending) begin
+                wb_ack <= 1'b1;
+                wb_rdt <= wb_mem_read_oob ? 32'b0 :
+                          (wb_mem_read_half ? wb_mem_rdata[63:32] : wb_mem_rdata[31:0]);
+                wb_mem_read_pending <= 1'b0;
+            end else if(wb_cyc & wb_stb) begin
+                if(wb_we) begin
+                    wb_ack <= 1'b1;
+                    wb_rdt <= 32'b0;
+                    if(wb_is_reg) begin
+                        // Keep register write decode in one case so new writable registers
+                        // can be added without touching memory-path logic.
+                        case(wb_reg_idx)
+                            reg_control: begin
+                                if(wb_sel[0]) begin
+                                    // Bit 0: write-1 pulse to arm/rearm scope.
+                                    if(wb_dat[0])
+                                        arm_req <= 1'b1;
+                                    // Bit 1: trigger enable.
+                                    trigger_enable <= wb_dat[1];
+                                    // Bits [3:2]: trigger channel (0=a,1=b,2=c,3=d).
+                                    trigger_channel <= wb_dat[3:2];
+                                end
+                            end
+                            reg_trig_val: begin
+                                if(wb_sel[0]) trig_val[7:0] <= wb_dat[7:0];
+                                if(wb_sel[1]) trig_val[15:8] <= wb_dat[15:8];
+                            end
+                            default: begin
+                            end
+                        endcase
+                    end
+                end else begin
+                    if(wb_is_reg) begin
+                        wb_ack <= 1'b1;
+                        case(wb_reg_idx)
+                            // [3:2]=trigger_channel, [1]=trigger_enable, [0]=arm(write pulse only/read 0).
+                            reg_control: wb_rdt <= {28'b0, trigger_channel, trigger_enable, 1'b0};
+                            // [0]=triggered, [1]=capturing, [2]=armed, [3]=done
+                            reg_status: wb_rdt <= {28'b0, capture_done, scope_armed, count_enable, scope_triggered};
+                            reg_trig_val: wb_rdt <= {16'b0, trig_val};
+                            default: wb_rdt <= 32'b0;
+                        endcase
+                    end else begin
+                        // Synchronous RAM read for BRAM inference: issue read now, acknowledge next cycle.
+                        wb_mem_rdata <= mem[wb_mem_idx];
+                        wb_mem_read_half <= wb_adr[2];
+                        wb_mem_read_oob <= (wb_mem_idx > depth_last);
+                        wb_mem_read_pending <= 1'b1;
+                    end
+                end
+            end
+
+        end
+    end
+
+endmodule

cores/signal/signal_scope/signal_scope_q15.core

@@ -0,0 +1,32 @@
+CAPI=2:
+
+name: joppeb:signal:signal_scope_q15:1.0
+description: Simple signal capture buffer for debug/scope use
+
+filesets:
+    rtl:
+        depend:
+            - joppeb:util:clog2
+            - joppeb:wb:jtag_wb_bridge
+        files:
+            - rtl/signal_scope_q15.v
+        file_type: verilogSource
+
+targets:
+    default:
+        filesets:
+            - rtl
+        toplevel: signal_scope_q15
+        parameters:
+            - depth
+            - chain
+
+parameters:
+    depth:
+        datatype: int
+        description: Number of samples stored in internal memory
+        paramtype: vlogparam
+    chain:
+        datatype: int
+        description: JTAG chain identifier 
+        paramtype: vlogparam

cores/signal/signal_scope/tool/capture_plot.py

@@ -0,0 +1,243 @@
+#!/usr/bin/env python3
+import argparse
+import sys
+import time
+from pathlib import Path
+
+import matplotlib.pyplot as plt
+
+MEM_BASE = 0x00000000
+REG_BASE = 0x80000000
+REG_CONTROL = REG_BASE + 0x00
+REG_STATUS = REG_BASE + 0x04
+REG_TRIG_VAL = REG_BASE + 0x08
+
+
+def _add_bridge_module_path() -> None:
+    here = Path(__file__).resolve()
+    bridge_tool = here.parents[3] / "wb" / "jtag_wb_bridge" / "tool"
+    sys.path.insert(0, str(bridge_tool))
+
+
+def _to_signed(value: int, width: int) -> int:
+    if width <= 0:
+        return value
+    sign_bit = 1 << (width - 1)
+    mask = (1 << width) - 1
+    value &= mask
+    return value - (1 << width) if (value & sign_bit) else value
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description="Arm signal_scope once, dump samples over JTAG WB, and plot them."
+    )
+    parser.add_argument("--port", type=int, default=0, help="Digilent device index")
+    parser.add_argument("--chain", type=int, default=1, help="JTAG USER chain")
+    parser.add_argument("--selector", type=str, default=None, help="Optional device selector string")
+    parser.add_argument(
+        "--depth",
+        type=int,
+        default=1024,
+        help="Number of scope frames to read (must match RTL depth)",
+    )
+    parser.add_argument(
+        "--wait-s",
+        type=float,
+        default=0.05,
+        help="Seconds to wait after arm/dearm before reading",
+    )
+    parser.add_argument(
+        "--trigger-value",
+        type=lambda x: int(x, 0),
+        default=None,
+        help="Optional trigger threshold (16-bit, signal_a rising crossing). If omitted, triggering is disabled.",
+    )
+    parser.add_argument(
+        "--trigger-channel",
+        choices=["a", "b", "c", "d"],
+        default="a",
+        help="Trigger source channel when triggering is enabled",
+    )
+    parser.add_argument(
+        "--unsigned",
+        action="store_true",
+        help="Plot samples as unsigned (default: signed two's complement)",
+    )
+    parser.add_argument("--out", type=str, default=None, help="Optional PNG output path")
+    parser.add_argument(
+        "--dump-csv",
+        type=str,
+        default=None,
+        help="Optional CSV output path with columns: index,value",
+    )
+    parser.add_argument(
+        "--interactive",
+        action="store_true",
+        help="Keep running: press Enter to recapture/replot in the same window",
+    )
+    parser.add_argument(
+        "--continuous",
+        action="store_true",
+        help="Keep running and recapture continuously without waiting for Enter",
+    )
+    return parser.parse_args()
+
+
+def capture_once(bridge, args: argparse.Namespace) -> list[tuple[int, int, int, int]]:
+    samples = []
+    frame_count = args.depth
+    trigger_channel_map = {"a": 0, "b": 1, "c": 2, "d": 3}
+    trigger_channel = trigger_channel_map[args.trigger_channel]
+    if args.trigger_value is None:
+        print("[signal_scope] Arming scope with trigger disabled...")
+        bridge.write32(REG_CONTROL, 0x1)  # bit0: arm pulse, bit1: trigger enable=0
+    else:
+        trig_val = args.trigger_value & 0xFFFF
+        print(
+            f"[signal_scope] Config trigger: trig_val=0x{trig_val:04x}, "
+            f"source=signal_{args.trigger_channel} rising"
+        )
+        bridge.write32(REG_TRIG_VAL, trig_val)
+        print("[signal_scope] Arming scope with trigger enabled...")
+        bridge.write32(REG_CONTROL, 0x3 | (trigger_channel << 2))  # bit0: arm, bit1: trig_en, bits[3:2]: channel
+
+        # Wait until the new arm command is active, then wait for its trigger event.
+        while (bridge.read32(REG_STATUS) & 0x4) == 0:
+            time.sleep(0.001)
+
+        print("[signal_scope] Waiting for trigger...")
+        while True:
+            status = bridge.read32(REG_STATUS)
+            if status & 0x1:
+                break
+            time.sleep(0.001)
+
+    if args.wait_s > 0:
+        print(f"[signal_scope] Waiting {args.wait_s:.3f}s for capture to complete...")
+        time.sleep(args.wait_s)
+
+    print(f"[signal_scope] Reading back {frame_count} frames...")
+    for idx in range(frame_count):
+        base = MEM_BASE + idx * 8
+        low = bridge.read32(base)
+        high = bridge.read32(base + 4)
+
+        ch_a = low & 0xFFFF
+        ch_b = (low >> 16) & 0xFFFF
+        ch_c = high & 0xFFFF
+        ch_d = (high >> 16) & 0xFFFF
+        if not args.unsigned:
+            ch_a = _to_signed(ch_a, 16)
+            ch_b = _to_signed(ch_b, 16)
+            ch_c = _to_signed(ch_c, 16)
+            ch_d = _to_signed(ch_d, 16)
+        samples.append((ch_a, ch_b, ch_c, ch_d))
+        if idx and (idx % max(1, frame_count // 10) == 0):
+            pct = (100 * idx) // frame_count
+    print(f"[signal_scope] Read complete: {len(samples)} frames")
+    return samples
+
+
+def write_csv(samples: list[tuple[int, int, int, int]], csv_path: Path) -> None:
+    print(f"[signal_scope] Writing CSV to {csv_path}...")
+    with csv_path.open("w", encoding="utf-8") as f:
+        f.write("index,ch_a,ch_b,ch_c,ch_d\n")
+        for idx, values in enumerate(samples):
+            f.write(f"{idx},{values[0]},{values[1]},{values[2]},{values[3]}\n")
+    print(f"Wrote CSV: {csv_path}")
+
+
+def plot_samples(ax, samples: list[tuple[int, int, int, int]], args: argparse.Namespace, capture_idx: int) -> None:
+    series = [[], [], [], []]
+    for ch_a, ch_b, ch_c, ch_d in samples:
+        series[0].append(ch_a)
+        series[1].append(ch_b)
+        series[2].append(ch_c)
+        series[3].append(ch_d)
+
+    ax.cla()
+    ax.plot(series[0], linewidth=1, label="ch_d")
+    ax.plot(series[1], linewidth=1, label="ch_c")
+    ax.plot(series[2], linewidth=1, label="ch_b")
+    ax.plot(series[3], linewidth=1, label="ch_a")
+    ax.set_title(f"signal_scope_q15 capture #{capture_idx} (depth={args.depth}, chain={args.chain})")
+    ax.set_xlabel("Sample")
+    ax.set_ylabel("Value")
+    if not args.unsigned:
+        ax.set_ylim([-2**15, 2**15])
+    ax.grid(True, alpha=0.3)
+    ax.legend(loc="upper right")
+
+
+def main() -> int:
+    args = parse_args()
+
+    if args.depth <= 0:
+        raise ValueError("--depth must be > 0")
+
+    _add_bridge_module_path()
+    from libjtag_wb_bridge.jtag_bridge import JtagBridge  # pylint: disable=import-error
+
+    print(
+        f"[signal_scope] Starting capture: port={args.port}, chain={args.chain}, "
+        f"depth={args.depth}, selector={args.selector!r}"
+    )
+
+    with JtagBridge() as bridge:
+        print("[signal_scope] Opening JTAG bridge...")
+        if args.selector:
+            bridge.open_selector(args.selector, port=args.port, chain=args.chain)
+        else:
+            bridge.open(port=args.port, chain=args.chain)
+        print("[signal_scope] Bridge opened")
+
+        print("[signal_scope] Clearing bridge flags and sending ping...")
+        bridge.clear_flags()
+        bridge.ping()
+        print("[signal_scope] Bridge ready")
+        status = bridge.read32(REG_STATUS)
+        print(f"[signal_scope] Status: 0x{status:08x}")
+
+        fig, ax = plt.subplots(figsize=(12, 4))
+        capture_idx = 1
+
+        while True:
+            print(f"[signal_scope] Capture cycle #{capture_idx}")
+            samples = capture_once(bridge, args)
+            plot_samples(ax, samples, args, capture_idx)
+            fig.tight_layout()
+            fig.canvas.draw_idle()
+            fig.canvas.flush_events()
+
+            if args.dump_csv:
+                write_csv(samples, Path(args.dump_csv))
+
+            if args.out:
+                out_path = Path(args.out)
+                print(f"[signal_scope] Saving plot to {out_path}...")
+                fig.savefig(out_path, dpi=150)
+                print(f"Wrote plot: {out_path}")
+
+            if not args.interactive and not args.continuous:
+                break
+
+            plt.show(block=False)
+            if args.continuous:
+                capture_idx += 1
+                continue
+            answer = input("[signal_scope] Press Enter to recapture, or 'q' + Enter to quit: ")
+            if answer.strip().lower().startswith("q"):
+                break
+            capture_idx += 1
+
+        if not args.out:
+            print("[signal_scope] Showing plot window...")
+            plt.show()
+
+    print("[signal_scope] Done")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

cores/system/mcu/rtl/mcu_peripherals.v

@@ -91,11 +91,10 @@ module mcu_peripherals (
     );
 
     wb_gpio_banks #(
-        .BASE_ADDR(GPIO_BASE_ADDR),
+        .num_banks(4)
-        .NUM_BANKS(4)
     ) gpio (
-        .i_wb_clk(i_clk),
+        .i_clk(i_clk),
-        .i_wb_rst(i_rst),
+        .i_rst(i_rst),
         .i_wb_dat(gpio_wbs_dat_w),
         .i_wb_adr(gpio_wbs_adr),
         .i_wb_we(gpio_wbs_we),

cores/system/mimas_sd_adc_r2r/mimas.ucf

@@ -0,0 +1,54 @@
+# Main clock input
+NET "aclk" LOC = P126;
+NET "aclk" TNM_NET = "SYS_CLK_PIN";
+TIMESPEC TS_SYS_CLK_PIN = PERIOD "SYS_CLK_PIN" 10 ns HIGH 50 %;
+
+# Boards button row
+NET "aresetn" LOC = P120;
+NET "aresetn" IOSTANDARD = LVCMOS33;
+NET "aresetn" PULLUP;
+
+NET "adc_a" LOC = P33;
+NET "adc_a" IOSTANDARD = LVDS_33;
+NET "adc_b" LOC = P32;
+NET "adc_b" IOSTANDARD = LVDS_33;
+NET "adc_o" LOC = P34;
+NET "adc_o" IOSTANDARD = LVCMOS33;
+
+NET "r2r[0]" LOC = P131;
+NET "r2r[1]" LOC = P133;
+NET "r2r[2]" LOC = P137;
+NET "r2r[3]" LOC = P139;
+NET "r2r[4]" LOC = P141;
+NET "r2r[5]" LOC = P1;
+NET "r2r[0]" IOSTANDARD = LVCMOS33;
+NET "r2r[1]" IOSTANDARD = LVCMOS33;
+NET "r2r[2]" IOSTANDARD = LVCMOS33;
+NET "r2r[3]" IOSTANDARD = LVCMOS33;
+NET "r2r[4]" IOSTANDARD = LVCMOS33;
+NET "r2r[5]" IOSTANDARD = LVCMOS33;
+
+NET "LED[0]" LOC = P119;
+NET "LED[0]" IOSTANDARD = LVCMOS33;
+NET "LED[0]" DRIVE = 8;
+NET "LED[1]" LOC = P118;
+NET "LED[1]" IOSTANDARD = LVCMOS33;
+NET "LED[1]" DRIVE = 8;
+NET "LED[2]" LOC = P117;
+NET "LED[2]" IOSTANDARD = LVCMOS33;
+NET "LED[2]" DRIVE = 8;
+NET "LED[3]" LOC = P116;
+NET "LED[3]" IOSTANDARD = LVCMOS33;
+NET "LED[3]" DRIVE = 8;
+NET "LED[4]" LOC = P115;
+NET "LED[4]" IOSTANDARD = LVCMOS33;
+NET "LED[4]" DRIVE = 8;
+NET "LED[5]" LOC = P114;
+NET "LED[5]" IOSTANDARD = LVCMOS33;
+NET "LED[5]" DRIVE = 8;
+NET "LED[6]" LOC = P112;
+NET "LED[6]" IOSTANDARD = LVCMOS33;
+NET "LED[6]" DRIVE = 8;
+NET "LED[7]" LOC = P111;
+NET "LED[7]" IOSTANDARD = LVCMOS33;
+NET "LED[7]" DRIVE = 8;

cores/system/mimas_sd_adc_r2r/mimas_sd_adc_r2r.core

@@ -0,0 +1,47 @@
+CAPI=2:
+
+name: joppeb:system:mimas_sd_adc_r2r:1.0
+description: Mimas top-level wiring sigma-delta ADC output directly to R2R DAC
+
+filesets:
+    rtl:
+        depend:
+            - joppeb:primitive:clkgen
+            - joppeb:signal:sd_adc_q15
+            - joppeb:util:conv
+            - joppeb:signal:signal_scope_q15
+        files:
+            - rtl/toplevel.v
+        file_type: verilogSource
+
+    mimas:
+        files:
+            - mimas.ucf : {file_type : UCF}
+            - options.tcl : {file_type : tclSource}
+
+targets:
+    default:
+        filesets:
+            - rtl
+        toplevel: toplevel
+
+    mimas:
+        filesets:
+            - rtl
+            - mimas
+        toplevel: toplevel
+        parameters:
+            - FPGA_SPARTAN6=true
+        default_tool: ise
+        tools:
+            ise:
+                family: Spartan6
+                device: xc6slx9
+                package: tqg144
+                speed: -2
+
+parameters:
+    FPGA_SPARTAN6:
+        datatype: bool
+        description: Select Spartan-6 family specific implementations
+        paramtype: vlogdefine

cores/system/mimas_sd_adc_r2r/options.tcl

@@ -0,0 +1,2 @@
+project set "Create Binary Configuration File" TRUE -process "Generate Programming File"
+project set "Keep Hierarchy" Yes -process "Synthesize - XST"

cores/system/mimas_sd_adc_r2r/rtl/toplevel.v

@@ -0,0 +1,106 @@
+`timescale 1ns/1ps
+
+module toplevel(
+    input wire aclk,
+    input wire aresetn,
+
+    input wire adc_a,
+    input wire adc_b,
+    output wire adc_o,
+
+    output wire [5:0] r2r,
+    output wire [7:0] LED
+);
+    `include "conv.vh"
+
+    // Clocking
+    wire clk_100;
+    assign clk_100 = aclk;
+    wire clk_15;
+    clkgen #(
+        .CLK_IN_HZ(100000000),
+        .CLKFX_DIVIDE(20),
+        .CLKFX_MULTIPLY(3)
+    ) clk_gen_15 (
+        .clk_in(clk_100),
+        .clk_out(clk_15)
+    );
+
+    // Asynchronous assert on reset button, synchronous release in clk_15 domain.
+    localparam [17:0] RESET_RELEASE_CYCLES = 18'd150000; // ~10 ms @ 15 MHz
+    reg [17:0] rst_cnt = 18'd0;
+    reg        sys_reset_r = 1'b1;
+    always @(posedge clk_15 or negedge aresetn) begin
+        if (!aresetn) begin
+            rst_cnt <= 18'd0;
+            sys_reset_r <= 1'b1;
+        end else if (sys_reset_r) begin
+            if (rst_cnt == RESET_RELEASE_CYCLES - 1'b1)
+                sys_reset_r <= 1'b0;
+            else
+                rst_cnt <= rst_cnt + 1'b1;
+        end
+    end
+
+    wire signed [15:0] signal_q15;
+    wire signal_valid;
+    sd_adc_q15 #(
+        .R_OHM(3300),
+        .C_PF(220)
+    ) sd_adc (
+        .i_clk_15(clk_15),
+        .i_rst_n(!sys_reset_r),
+        .i_adc_a(adc_a),
+        .i_adc_b(adc_b),
+        .o_adc(adc_o),
+        .o_signal_q15(signal_q15),
+        .o_signal_valid(signal_valid)
+    );
+
+    // signal_q15 is unipolar and biased (0-3.3V -> 0..32767)
+    reg signed [15:0] signal_unbiased_q15 = 16'sd0;
+    reg signal_unbiased_valid = 1'b0;
+    localparam bias = 2**14;
+    localparam gain = 2;
+    always @(posedge clk_15) begin
+        if (sys_reset_r) begin
+            signal_unbiased_q15 <= 16'sd0;
+            signal_unbiased_valid <= 1'b0;
+        end else begin
+            signal_unbiased_valid <= signal_valid;
+            if (signal_valid) begin
+                signal_unbiased_q15 <= (signal_q15 - $signed(bias)) * gain;
+            end
+        end
+    end
+
+    reg [5:0] dac_code = 6'd0;
+    always @(posedge clk_15) begin
+        if (sys_reset_r)
+            dac_code <= 6'd0;
+        else if (signal_unbiased_valid)
+            dac_code <= q15_to_uq16(signal_unbiased_q15) >> 10;
+    end
+
+    assign r2r = dac_code;
+
+    // Quick status indication: show ADC validity and most recent DAC code.
+    assign LED[0] = signal_valid;
+    assign LED[6:1] = dac_code;
+    assign LED[7] = sys_reset_r;
+
+
+    signal_scope_q15 #(
+        .depth(2**13),
+        .chain(1)
+    ) scope1 (
+        .i_clk(clk_15),
+        .i_rst(sys_reset_r),
+        .i_signal_a(signal_q15),
+        .i_signal_valid_a(signal_valid),
+        .i_signal_b(signal_unbiased_q15),
+        .i_signal_valid_b(signal_unbiased_valid),
+        .i_signal_valid_c(signal_valid),
+        .i_signal_valid_d(signal_valid)
+    );
+endmodule

cores/system/test/rtl/toplevel.v

@@ -81,12 +81,12 @@ module toplevel #(
         .CLK_HZ(15_000_000),
         .FS_HZ(80_000)
     ) nco (
-        .clk    (clk_15),
+        .i_clk    (clk_15),
-        .rst_n  (sys_resetn),
+        .i_rst_n  (sys_resetn),
-        .freq_hz(GPIO_A),
+        .i_freq_hz(GPIO_A),
-        .sin_q15(sin_q15),
+        .o_sin_q15(sin_q15),
-        .cos_q15(),
+        .o_cos_q15(),
-        .clk_en (clk_en)
+        .o_clk_en (clk_en)
     );
 
     reg [5:0] dac_code;

cores/system/test/sw/sweep/sweep.c

@@ -35,13 +35,13 @@ void main(){
     irq_init();
 
     *LEDGR = 1;
-    *TIMER_LD = 2 * 15000000/1000;
+    *TIMER_LD = 1000 * 15000;
 
     for(;;){
-        for(int i=1000; i<10000; i+=10){
+        for(int i=500; i<6000; i+=10){
             *R_FREQ = i;
             *LEDS = i>>4;
-            // for(int j=0; j<80; j++) asm volatile("nop");
+            for(int j=0; j<800; j++) asm volatile("nop");
         }
     }
 }

cores/util/mul_const/mul_const.core

@@ -0,0 +1,15 @@
+CAPI=2:
+
+name: joppeb:util:mul_const:1.0
+description: Constant multiplier helpers implemented with shift-add logic
+
+filesets:
+    rtl:
+        files:
+            - rtl/mul_const.v
+        file_type: verilogSource
+
+targets:
+    default:
+        filesets:
+            - rtl

cores/util/mul_const/rtl/mul_const.v

@@ -0,0 +1,31 @@
+`timescale 1ns/1ps
+
+module mul_const_shiftadd #(
+    parameter integer C = 0,
+    parameter integer IN_W = 16,
+    parameter integer OUT_W = 32
+)(
+    input  wire signed [IN_W-1:0] i_x,
+    output reg  signed [OUT_W-1:0] o_y
+);
+    integer k;
+    integer abs_c;
+    reg signed [OUT_W-1:0] acc;
+    reg signed [OUT_W-1:0] x_ext;
+
+    always @* begin
+        abs_c = (C < 0) ? -C : C;
+        acc = {OUT_W{1'b0}};
+        x_ext = {{(OUT_W-IN_W){i_x[IN_W-1]}}, i_x};
+
+        for (k = 0; k < 32; k = k + 1) begin
+            if (abs_c[k])
+                acc = acc + (x_ext <<< k);
+        end
+
+        if (C < 0)
+            o_y = -acc;
+        else
+            o_y = acc;
+    end
+endmodule

cores/wb/wb_gpio_banks/rtl/wb_gpio_banks.v

@@ -13,7 +13,7 @@ module wb_gpio_banks #(
     input  wire         i_wb_we,
     input  wire         i_wb_cyc,
     input  wire         i_wb_stb,
-    output wire         o_wb_ack,
+    output reg          o_wb_ack,
 
 	input wire [num_banks*32-1:0] i_gpio,
 	output wire [num_banks*32-1:0] o_gpio
@@ -48,8 +48,8 @@ module wb_gpio_banks #(
 
 	integer bi;
 	always @* begin
-		o_wb_rdt = 0;
+		o_wb_rdt = 32'h00000000;
-		o_wb_ack = 0;
+		o_wb_ack = 1'b0;
 		for(bi=0; bi<num_banks; bi=bi+1) begin
 			if(bank_sel[bi]) begin
 				o_wb_rdt = bank_rdt[bi*32 +: 32];

modem/modem_dtmf.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+
+import argparse
+import sys
+import time
+import serial
+
+def read_response(port: serial.Serial, timeout_s: float) -> list[str]:
+    deadline = time.monotonic() + timeout_s
+    lines: list[str] = []
+
+    while time.monotonic() < deadline:
+        raw = port.readline()
+        if not raw:
+            continue
+
+        line = raw.decode(errors="replace").strip()
+        if not line:
+            continue
+
+        lines.append(line)
+        if line in {"OK", "ERROR"}:
+            break
+
+    return lines
+
+def send_at(port: serial.Serial, command: str, timeout_s: float) -> tuple[bool, list[str]]:
+    port.write((command + "\r").encode())
+    port.flush()
+    lines = read_response(port, timeout_s)
+
+    ok = any(line == "OK" for line in lines)
+    err = any(line == "ERROR" for line in lines)
+    return ok and not err, lines
+
+def send_and_log(port: serial.Serial, command: str, timeout_s: float) -> tuple[bool, list[str]]:
+    ok, lines = send_at(port, command, timeout_s)
+    print(f"> {command}")
+    for line in lines:
+        print(f"< {line}")
+    return ok, lines
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="Control an AT modem and send DTMF tones")
+    parser.add_argument("device", help="Serial device path, e.g. /dev/ttyACM0")
+    parser.add_argument("--baud", type=int, default=115200, help="Serial baudrate (default: 115200)")
+    parser.add_argument("--timeout", type=float, default=2.0, help="AT command timeout seconds")
+    args = parser.parse_args()
+
+    try:
+        with serial.Serial(args.device, args.baud, timeout=0.2, write_timeout=1.0) as port:
+            port.reset_input_buffer()
+            port.reset_output_buffer()
+
+            # Inicialise
+
+            for cmd in ("AT", "ATZ0", "ATE1", "ATX0"):
+                ok, lines = send_and_log(port, cmd, args.timeout)
+                if not ok:
+                    print(f"Modem did not accept {cmd}", file=sys.stderr)
+                    return 1
+
+            send_and_log(port, "ATS6=0", args.timeout) # Set wait for dial tone time to 0
+            send_and_log(port, "ATS11=2", args.timeout) # set tone length to 1 ms
+            send_and_log(port, "ATH1", args.timeout)
+            while True:
+                send_and_log(port, "ATDT0123456789;", args.timeout)
+            send_and_log(port, "ATH0", args.timeout)
+
+    except serial.SerialException as exc:
+        print(f"Serial error: {exc}", file=sys.stderr)
+        return 1
+
+    print("Done")
+    return 0
+
+if __name__ == "__main__":
+    raise SystemExit(main())