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// -*- verilog -*-
//
// USRP - Universal Software Radio Peripheral
//
// Copyright (C) 2003 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
//
// Interface to Cypress FX2 bus
// A packet is 512 Bytes. Each fifo line is 4 bytes
// Fifo has 1024 or 2048 lines
module bus_interface
( input usbclk,
input reset,
inout [15:0] usbdata, // TRISTATE
input wire [5:0] usbctl,
output wire [5:0] usbrdy,
output [31:0] txdata,
input [31:0] rxdata,
input txclk,
input txstrobe,
input rxclk,
input rxstrobe,
output [11:0] debugbus,
input clear_status
);
parameter IN_CHANNELS = 1;
parameter OUT_CHANNELS = 1;
parameter bitmask = (IN_CHANNELS*2)-1;
wire have_space, have_pkt_rdy;
wire WR, RD, OE;
reg tx_underrun, rx_overrun;
assign WR = usbctl[0];
assign RD = usbctl[1];
assign OE = usbctl[2];
assign usbrdy[0] = have_space;
assign usbrdy[1] = have_pkt_rdy;
assign usbrdy[2] = tx_underrun;
assign usbrdy[3] = rx_overrun;
reg [IN_CHANNELS*2*16-1:0] fifo_in;
wire [OUT_CHANNELS*2*16-1:0] fifo_out;
wire [15:0] usbdata_in = usbdata;
reg select_out;
reg select_in;
reg commit;
reg rd_next;
reg [15:0] usbdata_out;
wire [10:0] txfifolevel,rxfifolevel;
reg [8:0] write_count;
wire tx_empty;
wire tx_full;
wire rx_empty;
wire rx_full;
wire [31:0] txd;
wire rdreq;
// Tri-state bus macro
bustri bustri(.data(usbdata_out),
.enabledt(OE),
.tridata(usbdata) );
//////////////////////////////////////////////
// TX Side (USB --> DAC)
always @(posedge usbclk, posedge reset)
begin
if(reset)
begin
fifo_in <= #1 0;
write_count <= #1 0;
end
else
if(WR & ~write_count[8])
begin
case(write_count[0])
1'b0 : fifo_in[31:16] <= #1 usbdata_in; // I
1'b1 : fifo_in[15:0] <= #1 usbdata_in; // Q
endcase
write_count <= #1 write_count + 9'd1;
end
else
write_count <= #1 WR ? write_count : 9'b0;
end
always @(posedge usbclk)
if(reset)
commit <= #1 1'b0;
else
if(write_count[0] && ~write_count[8] && WR)
commit <= #1 1'b1;
else
commit <= #1 1'b0;
assign rdreq = txstrobe & !tx_empty;
assign txdata = tx_empty ? 32'b0 : txd;
always @(posedge txclk)
if(reset)
tx_underrun <= 1'b0;
else if(txstrobe & tx_empty)
tx_underrun <= 1'b1;
else if(clear_status)
tx_underrun <= 1'b0;
fifo_1c_2k txfifo (.data ( fifo_in ),
.wrreq ( commit ),
.wrclk ( usbclk ),
.q ( txd ),
.rdreq ( rdreq),
.rdclk ( txclk ),
.aclr ( reset ),
.rdempty ( tx_empty ),
.rdusedw ( ),
.wrfull ( tx_full ),
.wrusedw ( txfifolevel )
);
assign have_space = (txfifolevel <= (2048-128));
//////////////////////////////
// Receive FIFO (ADC --> USB)
always @(posedge rxclk)
if(reset)
rx_overrun <= 1'b0;
else if(rxstrobe & rx_full)
rx_overrun <= 1'b1;
else if(clear_status)
rx_overrun <= 1'b0;
always @(select_out, fifo_out)
case(select_out)
0 : usbdata_out = fifo_out[31:16]; // I
1 : usbdata_out = fifo_out[15:0]; // Q
endcase
/*
always @(posedge usbclk, posedge reset)
if(reset)
usbdata_out <= #1 16'b0;
else
if(select_out)
usbdata_out = fifo_out[31:16];
else
usbdata_out = fifo_out[15:0];
*/
always @(negedge usbclk, posedge reset)
if(reset)
select_out <= #1 1'b0;
else if(~RD)
select_out <= #1 1'b0;
else
select_out <= #1 ~select_out;
fifo_1c_2k rxfifo (.data ( rxdata ), // counter ),
.wrreq (rxstrobe & ~rx_full ),
.wrclk ( rxclk ),
.q ( fifo_out ),
.rdreq ( select_out ),// & RD ), // FIXME
.rdclk ( usbclk ),
.aclr ( reset ),
.rdempty ( rx_empty ),
.rdusedw ( rxfifolevel ),
.wrfull ( rx_full ),
.wrusedw ( )
);
assign have_pkt_rdy = (rxfifolevel >= 128);
// Debugging Aids
assign debugbus[0] = tx_underrun;
assign debugbus[1] = rx_overrun;
assign debugbus[2] = tx_empty;
assign debugbus[3] = tx_full;
assign debugbus[4] = rx_empty;
assign debugbus[5] = rx_full;
assign debugbus[6] = txstrobe;
assign debugbus[7] = rxstrobe;
assign debugbus[8] = select_out;
assign debugbus[9] = rxstrobe & ~rx_full;
assign debugbus[10] = have_space;
assign debugbus[11] = have_pkt_rdy;
endmodule // bus_interface
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