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// -*- verilog -*-
//
// USRP - Universal Software Radio Peripheral
//
// Copyright (C) 2003,2004 Matt Ettus
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Boston, MA 02110-1301 USA
//
// Serial Control Bus from Cypress chip
module serial_io
( input master_clk,
input serial_clock,
input serial_data_in,
input enable,
input reset,
inout wire serial_data_out,
output reg [6:0] serial_addr,
output reg [31:0] serial_data,
output wire serial_strobe,
input wire [31:0] readback_0,
input wire [31:0] readback_1,
input wire [31:0] readback_2,
input wire [31:0] readback_3,
input wire [31:0] readback_4,
input wire [31:0] readback_5,
input wire [31:0] readback_6,
input wire [31:0] readback_7
);
reg is_read;
reg [7:0] ser_ctr;
reg write_done;
assign serial_data_out = is_read ? serial_data[31] : 1'bz;
always @(posedge serial_clock, posedge reset, negedge enable)
if(reset)
ser_ctr <= #1 8'd0;
else if(~enable)
ser_ctr <= #1 8'd0;
else if(ser_ctr == 39)
ser_ctr <= #1 8'd0;
else
ser_ctr <= #1 ser_ctr + 8'd1;
always @(posedge serial_clock, posedge reset, negedge enable)
if(reset)
is_read <= #1 1'b0;
else if(~enable)
is_read <= #1 1'b0;
else if((ser_ctr == 7)&&(serial_addr[6]==1))
is_read <= #1 1'b1;
always @(posedge serial_clock, posedge reset)
if(reset)
begin
serial_addr <= #1 7'b0;
serial_data <= #1 32'b0;
write_done <= #1 1'b0;
end
else if(~enable)
begin
//serial_addr <= #1 7'b0;
//serial_data <= #1 32'b0;
write_done <= #1 1'b0;
end
else
begin
if(~is_read && (ser_ctr == 39))
write_done <= #1 1'b1;
else
write_done <= #1 1'b0;
if(is_read & (ser_ctr==8))
case (serial_addr)
7'd1: serial_data <= #1 readback_0;
7'd2: serial_data <= #1 readback_1;
7'd3: serial_data <= #1 readback_2;
7'd4: serial_data <= #1 readback_3;
7'd5: serial_data <= #1 readback_4;
7'd6: serial_data <= #1 readback_5;
7'd7: serial_data <= #1 readback_6;
7'd8: serial_data <= #1 readback_7;
default: serial_data <= #1 32'd0;
endcase // case(serial_addr)
else if(ser_ctr >= 8)
serial_data <= #1 {serial_data[30:0],serial_data_in};
else if(ser_ctr < 8)
serial_addr <= #1 {serial_addr[5:0],serial_data_in};
end // else: !if(~enable)
reg enable_d1, enable_d2;
always @(posedge master_clk)
begin
enable_d1 <= #1 enable;
enable_d2 <= #1 enable_d1;
end
assign serial_strobe = enable_d2 & ~enable_d1;
endmodule // serial_io
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