source: trunk/MultiChannelUSB/usb_fifo.v@ 66

Last change on this file since 66 was 58, checked in by demin, 16 years ago

code cleanup
File size: 2.8 KB
RevLine 
[27]1module usb_fifo
2 (
3 input wire usb_clk,
4 inout wire [7:0] usb_data,
5 input wire usb_full, usb_empty,
6 output wire usb_wrreq, usb_rdreq, usb_rden, usb_pktend,
7 output wire [1:0] usb_addr,
8
9 input wire clk, aclr,
10 input wire tx_wrreq, rx_rdreq,
11 input wire [7:0] tx_data,
12 output wire tx_full, rx_empty,
[36]13 output wire [7:0] rx_q
[27]14 );
15
[33]16 wire int_rx_full, int_tx_empty;
[36]17 wire rx_ready, tx_ready;
[33]18 wire int_rdreq, int_wrreq, int_pktend;
19 reg is_rx_addr_ok;
[30]20 reg [8:0] byte_counter;
21 reg [4:0] idle_counter;
[27]22
[33]23 wire [7:0] int_rx_data = usb_data;
24 wire [7:0] int_tx_q;
[31]25
[45]26 dcfifo #(
27 .intended_device_family("Cyclone III"),
28 .lpm_numwords(16),
29 .lpm_showahead("ON"),
30 .lpm_type("dcfifo"),
31 .lpm_width(8),
32 .lpm_widthu(4),
33 .rdsync_delaypipe(4),
34 .wrsync_delaypipe(4),
35 .overflow_checking("ON"),
36 .underflow_checking("ON"),
37 .use_eab("OFF"),
38 .write_aclr_synch("OFF")) fifo_tx (
[27]39 .aclr(aclr),
40 .data(tx_data),
41 .rdclk(usb_clk),
[31]42 .rdreq(int_wrreq),
[27]43 .wrclk(clk),
44 .wrreq(tx_wrreq),
[33]45 .q(int_tx_q),
46 .rdempty(int_tx_empty),
[45]47 .wrfull(tx_full),
48 .rdfull(),
49 .rdusedw(),
50 .wrempty(),
51 .wrusedw());
[27]52
[45]53 dcfifo #(
54 .intended_device_family("Cyclone III"),
55 .lpm_numwords(16),
56 .lpm_showahead("ON"),
57 .lpm_type("dcfifo"),
58 .lpm_width(8),
59 .lpm_widthu(4),
60 .rdsync_delaypipe(4),
61 .wrsync_delaypipe(4),
62 .overflow_checking("ON"),
63 .underflow_checking("ON"),
64 .use_eab("OFF"),
65 .write_aclr_synch("OFF")) fifo_rx (
[27]66 .aclr(aclr),
[33]67 .data(int_rx_data),
[27]68 .rdclk(clk),
69 .rdreq(rx_rdreq),
70 .wrclk(usb_clk),
[31]71 .wrreq(int_rdreq),
[33]72 .q(rx_q),
[27]73 .rdempty(rx_empty),
[45]74 .wrfull(int_rx_full),
75 .rdfull(),
76 .rdusedw(),
77 .wrempty(),
78 .wrusedw());
[33]79
80 assign rx_ready = (~usb_empty) & (~int_rx_full) & (~int_pktend);
81 assign tx_ready = (~rx_ready) & (~usb_full) & (~int_tx_empty) & (~int_pktend);
[31]82
[33]83 assign int_rdreq = (rx_ready) & (is_rx_addr_ok);
84 assign int_wrreq = (tx_ready) & (~is_rx_addr_ok);
85
86 assign int_pktend = (&idle_counter);
87
[30]88 always @ (posedge usb_clk)
[27]89 begin
[33]90 // respect 1 clock delay between fifo selection
91 // and data transfer operations
92 is_rx_addr_ok <= rx_ready;
93
94 // assert pktend if buffer contains unsent data
95 // and fifo_tx_unit stays empty for more than 30 clocks
96 if (int_pktend)
[30]97 begin
98 byte_counter <= 9'd0;
99 idle_counter <= 5'd0;
100 end
[33]101 else if (int_wrreq)
[30]102 begin
103 byte_counter <= byte_counter + 9'd1;
104 idle_counter <= 5'd0;
105 end
[33]106 else if ((|byte_counter) & (int_tx_empty) & (~rx_ready))
[30]107 begin
108 byte_counter <= byte_counter;
109 idle_counter <= idle_counter + 5'd1;
110 end
[33]111
[27]112 end
113
[33]114 assign usb_pktend = int_pktend;
[31]115 assign usb_rdreq = int_rdreq;
116 assign usb_wrreq = int_wrreq;
[33]117 assign usb_rden = int_rdreq;
118 assign usb_addr = {1'b1, ~rx_ready};
119 assign usb_data = int_wrreq ? int_tx_q : 8'bz;
[27]120
[58]121endmodule
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