module dac_sim #( parameter POLARITY = 0, parameter PHASE = 1, parameter WID = 24, parameter DATA_WID = 20, parameter WID_LEN = 5 ) ( input clk, output reg [DATA_WID-1:0] curset, input mosi, output miso, input sck, input ss_L, output err ); wire [WID-1:0] from_master; reg [WID-1:0] to_master = 0; reg rdy = 1; wire spi_fin; reg [WID-4-1:0] ctrl_register = 0; always @ (posedge clk) begin if (spi_fin) begin rdy <= 0; case (from_master[WID-1:WID-4]) 4'b1001: begin to_master <= {4'b1001, curset}; end 4'b0001: begin curset <= from_master [DATA_WID-1:0]; to_master <= 0; end 4'b0010: begin ctrl_register <= to_master[WID-1-4:0]; to_master <= 0; end 4'b1010: begin to_master <= {4'b1010, ctrl_register}; end default: to_master <= 0; endcase end else if (!rdy) begin rdy <= 1; end end spi_slave #( .WID(WID), .WID_LEN(WID_LEN), .POLARITY(POLARITY), .PHASE(PHASE) ) spi ( .clk(clk), .sck(sck), .ss_L(ss_L), .miso(miso), .mosi(mosi), .from_master(from_master), .to_master(to_master), .finished(spi_fin), .rdy(rdy), .err(err) ); endmodule `undefineall