axi_dac_interpolate: Add last sample support

This feature will allow the user to hold(indefinitely) the last sample, from an
ongoing DMA transfer, simple or cyclic(stooped by user or trigger).

This commit also adds as functionality option:
-synchronized stop between the two channels(DMAs)
-stop by trigger

library/axi_dac_interpolate/axi_dac_interpolate.v

@@ -56,6 +56,9 @@ module axi_dac_interpolate #(
   input                 dac_enable_b,
   output      [15:0]    dac_int_data_a,
   output      [15:0]    dac_int_data_b,
+  output                dac_valid_out_a,
+  output                dac_valid_out_b,
+  output                hold_last_sample,
   output                underflow,
 
   input       [ 1:0]    trigger_i,
@@ -130,6 +133,8 @@ module axi_dac_interpolate #(
   wire    [15:0]    dac_correction_coefficient_b;
   wire    [19:0]    trigger_config;
 
+  wire              en_start_trigger;
+  wire              en_stop_trigger;
   wire    [ 1:0]    en_trigger_pins;
   wire              en_trigger_adc;
   wire              en_trigger_la;
@@ -141,11 +146,15 @@ module axi_dac_interpolate #(
   wire    [ 1:0]    fall_edge;
 
   wire              trigger_active;
+  wire              trigger;
   wire              ext_trigger;
 
   wire              underflow_a;
   wire              underflow_b;
 
+  wire    [ 1:0]    lsample_hold_config;
+  wire              sync_stop_channels;
+
   // signal name changes
 
   assign up_clk = s_axi_aclk;
@@ -159,6 +168,8 @@ module axi_dac_interpolate #(
   assign rise_edge  = trigger_config[7:6];
   assign fall_edge  = trigger_config[9:8];
 
+  assign en_start_trigger = trigger_config[14];
+  assign en_stop_trigger  = trigger_config[15];
   assign en_trigger_pins  = trigger_config[17:16];
   assign en_trigger_adc   = trigger_config[18];
   assign en_trigger_la    = trigger_config[19];
@@ -195,6 +206,9 @@ module axi_dac_interpolate #(
    low_level_trigger <= ~trigger_i_m3 & low_level;
   end
 
+  assign hold_last_sample = lsample_hold_config[0];
+  assign sync_stop_channels = lsample_hold_config[1];
+
   assign underflow = underflow_a | underflow_b;
 
   axi_dac_interpolate_filter #(
@@ -205,6 +219,8 @@ module axi_dac_interpolate #(
 
     .dac_data (dac_data_a),
     .dac_valid (dac_valid_a),
+    .dac_valid_out (dac_valid_out_a),
+    .sync_stop_channels (sync_stop_channels),
 
     .dac_enable (dac_enable_a),
     .dac_int_data (dac_int_data_a),
@@ -217,6 +233,8 @@ module axi_dac_interpolate #(
     .start_sync_channels (start_sync_channels),
     .trigger (trigger),
     .trigger_active (trigger_active),
+    .en_start_trigger (en_start_trigger),
+    .en_stop_trigger (en_stop_trigger),
     .dma_valid (dma_valid_a),
     .dma_valid_adjacent (dma_valid_b),
     .dac_correction_enable(dac_correction_enable_a),
@@ -231,6 +249,8 @@ module axi_dac_interpolate #(
 
     .dac_data (dac_data_b),
     .dac_valid (dac_valid_b),
+    .dac_valid_out (dac_valid_out_b),
+    .sync_stop_channels (sync_stop_channels),
     .underflow (underflow_b),
 
     .dac_enable (dac_enable_b),
@@ -243,6 +263,8 @@ module axi_dac_interpolate #(
     .start_sync_channels (start_sync_channels),
     .trigger (trigger),
     .trigger_active (trigger_active),
+    .en_start_trigger (en_start_trigger),
+    .en_stop_trigger (en_stop_trigger),
     .dma_valid (dma_valid_b),
     .dma_valid_adjacent (dma_valid_a),
     .dac_correction_enable(dac_correction_enable_b),
@@ -265,6 +287,7 @@ module axi_dac_interpolate #(
     .dac_correction_coefficient_a(dac_correction_coefficient_a),
     .dac_correction_coefficient_b(dac_correction_coefficient_b),
     .trigger_config (trigger_config),
+    .lsample_hold_config (lsample_hold_config),
 
     .up_rstn (up_rstn),
     .up_clk (up_clk),

library/axi_dac_interpolate/axi_dac_interpolate_filter.v

@@ -49,6 +49,8 @@ module axi_dac_interpolate_filter #(
   input                 dac_enable,
   output  reg [15:0]    dac_int_data,
   output                dma_ready,
+  output                dac_valid_out,
+  input                 sync_stop_channels,
   output                underflow,
 
   input       [ 2:0]    filter_mask,
@@ -59,6 +61,8 @@ module axi_dac_interpolate_filter #(
   input                 start_sync_channels,
   input                 trigger,
   input                 trigger_active,
+  input                 en_start_trigger,
+  input                 en_stop_trigger,
   input                 dma_valid,
   input                 dma_valid_adjacent
 );
@@ -78,6 +82,8 @@ module axi_dac_interpolate_filter #(
 
   reg               filter_enable = 1'b0;
   reg               transfer = 1'b0;
+  reg     [15:0]    dma_valid_m = 16'd0;
+  reg               stop_transfer = 1'd0;
 
   wire              dac_valid_corrected;
   wire    [15:0]    dac_data_corrected;
@@ -87,6 +93,9 @@ module axi_dac_interpolate_filter #(
   wire              dac_cic_valid;
   wire    [109:0]   dac_cic_data;
 
+  wire              dma_valid_ch_sync;
+  wire              dma_valid_ch;
+
   ad_iqcor #(.Q_OR_I_N (0),
     .DISABLE(CORRECTION_DISABLE),
     .SCALE_ONLY(1))
@@ -119,6 +128,21 @@ module axi_dac_interpolate_filter #(
     .filter_out (dac_cic_data),
     .ce_out (dac_cic_valid));
 
+  assign dma_valid_ch_sync = sync_stop_channels ?
+                             dma_valid & dma_valid_adjacent & !dma_transfer_suspend :
+                             dma_valid & !dma_transfer_suspend;
+
+  assign dma_valid_ch = dma_valid_ch_sync & !stop_transfer;
+  always @(posedge dac_clk) begin
+    if (dac_rst == 1'b1) begin
+      dma_valid_m <= 'd0;
+    end else begin
+      dma_valid_m <= {dma_valid_m[14:0], dma_valid_ch};
+    end
+  end
+
+  assign dac_valid_out = dma_valid_m[4'h5];
+
   always @(posedge dac_clk) begin
     filter_mask_d1 <= filter_mask;
     if (filter_mask_d1 != filter_mask) begin
@@ -151,7 +175,7 @@ module axi_dac_interpolate_filter #(
 
   always @(posedge dac_clk) begin
     if (dma_transfer_suspend == 1'b0) begin
-      transfer <= trigger ? 1'b1 : transfer | !trigger_active;
+      transfer <= trigger ? 1'b1 : transfer | !(trigger_active & en_start_trigger);
     end else begin
       transfer <= 1'b0;
     end
@@ -162,6 +186,11 @@ module axi_dac_interpolate_filter #(
     end
   end
 
+  always @(posedge dac_clk) begin
+    stop_transfer <= !en_stop_trigger | dma_transfer_suspend ? 1'b0 :
+                     stop_transfer | (trigger_active & trigger & transfer);
+  end
+
   assign dma_ready = transmit_ready ? dac_int_ready : 1'b0;
   assign underflow = dac_enable & dma_ready & ~dma_valid;
 

library/axi_dac_interpolate/axi_dac_interpolate_reg.v

@@ -50,6 +50,7 @@ module axi_dac_interpolate_reg(
   output      [15:0]  dac_correction_coefficient_a,
   output      [15:0]  dac_correction_coefficient_b,
   output      [19:0]  trigger_config,
+  output      [ 1:0]  lsample_hold_config,
  // bus interface
 
   input               up_rstn,
@@ -77,6 +78,7 @@ module axi_dac_interpolate_reg(
   reg     [15:0]  up_correction_coefficient_a = 16'h0;
   reg     [15:0]  up_correction_coefficient_b = 16'h0;
   reg     [19:0]  up_trigger_config = 20'h0;
+  reg     [ 1:0]  up_lsample_hold_config = 2'h0;
 
   wire    [ 1:0]  flags;
 
@@ -96,6 +98,7 @@ module axi_dac_interpolate_reg(
       up_correction_coefficient_a <= 'd0;
       up_correction_coefficient_b <= 'd0;
       up_trigger_config <= 'd0;
+      up_lsample_hold_config <= 'h0;
     end else begin
       up_wack <= up_wreq;
       if ((up_wreq == 1'b1) && (up_waddr[4:0] == 5'h1)) begin
@@ -128,6 +131,9 @@ module axi_dac_interpolate_reg(
       if ((up_wreq == 1'b1) && (up_waddr[4:0] == 5'h18)) begin
         up_trigger_config <= up_wdata[19:0];
       end
+      if ((up_wreq == 1'b1) && (up_waddr[4:0] == 5'h19)) begin
+        up_lsample_hold_config <= up_wdata[1:0];
+      end
     end
   end
 
@@ -152,6 +158,7 @@ module axi_dac_interpolate_reg(
           5'h16: up_rdata <= {16'h0,up_correction_coefficient_a};
           5'h17: up_rdata <= {16'h0,up_correction_coefficient_b};
           5'h18: up_rdata <= {12'h0,up_trigger_config};
+          5'h19: up_rdata <= {30'h0,up_lsample_hold_config};
           default: up_rdata <= 0;
         endcase
       end else begin
@@ -160,7 +167,7 @@ module axi_dac_interpolate_reg(
     end
   end
 
-   up_xfer_cntrl #(.DATA_WIDTH(126)) i_xfer_cntrl (
+   up_xfer_cntrl #(.DATA_WIDTH(128)) i_xfer_cntrl (
     .up_rstn (up_rstn),
     .up_clk (up_clk),
     .up_data_cntrl ({ up_config[1],               // 1
@@ -168,6 +175,7 @@ module axi_dac_interpolate_reg(
                       up_correction_coefficient_b,// 16
                       up_correction_coefficient_a,// 16
                       up_trigger_config,          // 20
+                      up_lsample_hold_config,     //  2
                       up_flags,                   //  2
                       up_interpolation_ratio_b,   // 32
                       up_interpolation_ratio_a,   // 32
@@ -182,6 +190,7 @@ module axi_dac_interpolate_reg(
                       dac_correction_coefficient_b, // 16
                       dac_correction_coefficient_a, // 16
                       trigger_config,               // 20
+                      lsample_hold_config,          // 2
                       flags,                        // 2
                       dac_interpolation_ratio_b,    // 32
                       dac_interpolation_ratio_a,    // 32