module gpmc_wb (input EM_CLK, input [15:0] EM_D_in, output [15:0] EM_D_out, input [10:1] EM_A, input [1:0] EM_NBE, input EM_NCS, input EM_NWE, input EM_NOE, input wb_clk, input wb_rst, output reg [10:0] wb_adr_o, output reg [15:0] wb_dat_mosi, input [15:0] wb_dat_miso, output reg [1:0] wb_sel_o, output wb_cyc_o, output reg wb_stb_o, output reg wb_we_o, input wb_ack_i); // //////////////////////////////////////////// // Control Path, Wishbone bus bridge (wb master) reg [1:0] cs_del, we_del, oe_del; // Synchronize the async control signals always @(posedge wb_clk) begin cs_del <= { cs_del[0], EM_NCS }; we_del <= { we_del[0], EM_NWE }; oe_del <= { oe_del[0], EM_NOE }; end always @(posedge wb_clk) if(cs_del == 2'b10) // Falling Edge wb_adr_o <= { EM_A, 1'b0 }; always @(posedge wb_clk) if(we_del == 2'b10) // Falling Edge begin wb_dat_mosi <= EM_D_in; wb_sel_o <= ~EM_NBE; end reg [15:0] EM_D_hold; always @(posedge wb_clk) if(wb_ack_i) EM_D_hold <= wb_dat_miso; assign EM_D_out = wb_ack_i ? wb_dat_miso : EM_D_hold; assign wb_cyc_o = wb_stb_o; always @(posedge wb_clk) if(~cs_del[0] & (we_del == 2'b10) ) wb_we_o <= 1; else if(wb_ack_i) // Turn off we when done. Could also use we_del[0], others... wb_we_o <= 0; // FIXME should this look at cs_del[1]? always @(posedge wb_clk) if(~cs_del[0] & ((we_del == 2'b10) | (oe_del == 2'b10))) wb_stb_o <= 1; else if(wb_ack_i) wb_stb_o <= 0; endmodule // gpmc_wb