LFMRI_firmware/cores/axis_red_pitaya_dac.v

`timescale 1 ns / 1 ps

module axis_red_pitaya_dac #
(
  parameter integer DAC_DATA_WIDTH = 14,
  parameter integer AXIS_TDATA_WIDTH = 32
)
(
  // PLL signals
  input  wire                        aclk,
  input  wire                        ddr_clk,
  input  wire                        wrt_clk,
  input  wire                        locked,

  // DAC signals
  output wire                        dac_clk,
  output wire                        dac_rst,
  output wire                        dac_sel,
  output wire                        dac_wrt,
  output wire [DAC_DATA_WIDTH-1:0]   dac_dat,

  // Slave side
  output wire                        s_axis_tready,
  input  wire [AXIS_TDATA_WIDTH-1:0] s_axis_tdata,
  input  wire                        s_axis_tvalid
);

  reg [DAC_DATA_WIDTH-1:0] int_dat_a_reg;
  reg [DAC_DATA_WIDTH-1:0] int_dat_b_reg;
  reg [1:0] int_rst_reg;

  wire [DAC_DATA_WIDTH-1:0] int_dat_a_wire;
  wire [DAC_DATA_WIDTH-1:0] int_dat_b_wire;

  assign int_dat_a_wire = s_axis_tdata[DAC_DATA_WIDTH-1:0];
  assign int_dat_b_wire = s_axis_tdata[AXIS_TDATA_WIDTH/2+DAC_DATA_WIDTH-1:AXIS_TDATA_WIDTH/2];

  genvar j;

  always @(posedge aclk)
  begin
    if(~locked | ~s_axis_tvalid)
    begin
      int_dat_a_reg <= {(DAC_DATA_WIDTH){1'b0}};
      int_dat_b_reg <= {(DAC_DATA_WIDTH){1'b0}};
    end
    else
    begin
      int_dat_a_reg <= {int_dat_a_wire[DAC_DATA_WIDTH-1], ~int_dat_a_wire[DAC_DATA_WIDTH-2:0]};
      int_dat_b_reg <= {int_dat_b_wire[DAC_DATA_WIDTH-1], ~int_dat_b_wire[DAC_DATA_WIDTH-2:0]};
    end
    int_rst_reg <= {int_rst_reg[0], ~locked | ~s_axis_tvalid};
  end

  ODDR #(
    .DDR_CLK_EDGE("SAME_EDGE"),
    .INIT(1'b0)
  ) ODDR_rst (
    .Q(dac_rst),
    .D1(int_rst_reg[1]),
    .D2(int_rst_reg[1]),
    .C(aclk),
    .CE(1'b1),
    .R(1'b0),
    .S(1'b0)
  );

  ODDR #(
    .DDR_CLK_EDGE("SAME_EDGE"),
    .INIT(1'b0)
  ) ODDR_sel (
    .Q(dac_sel),
    .D1(1'b1),
    .D2(1'b0),
    .C(aclk),
    .CE(1'b1),
    .R(1'b0),
    .S(1'b0)
  );

  ODDR #(
    .DDR_CLK_EDGE("SAME_EDGE"),
    .INIT(1'b0)
  ) ODDR_wrt (
    .Q(dac_wrt),
    .D1(1'b1),
    .D2(1'b0),
    .C(wrt_clk),
    .CE(1'b1),
    .R(1'b0),
    .S(1'b0)
  );

  ODDR #(
    .DDR_CLK_EDGE("SAME_EDGE"),
    .INIT(1'b0)
  ) ODDR_clk (
    .Q(dac_clk),
    .D1(1'b1),
    .D2(1'b0),
    .C(ddr_clk),
    .CE(1'b1),
    .R(1'b0),
    .S(1'b0)
  );

  generate
    for(j = 0; j < DAC_DATA_WIDTH; j = j + 1)
    begin : DAC_DAT
      ODDR #(
        .DDR_CLK_EDGE("SAME_EDGE"),
        .INIT(1'b0)
      ) ODDR_inst (
        .Q(dac_dat[j]),
        .D1(int_dat_b_reg[j]),
        .D2(int_dat_a_reg[j]),
        .C(aclk),
        .CE(1'b1),
        .R(1'b0),
        .S(1'b0)
      );
    end
  endgenerate

  assign s_axis_tready = 1'b1;

endmodule