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[/] [uart6551/] [trunk/] [trunk/] [rtl/] [uart6551Rx_x12.sv] - Blame information for rev 6

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// ============================================================================
//        __
//   \\__/ o\    (C) 2005-2022  Robert Finch, Waterloo
//    \  __ /    All rights reserved.
//     \/_//     robfinch@finitron.ca
//       ||
//
//
// BSD 3-Clause License
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// ============================================================================
//
`define IDLE    0
`define CNT             1
 
module uart6551Rx_x12(rst, clk,
        cyc, cs, wr, dout, ack,
        fifoEnable, fifoClear, clearGErr,
        parityCtrl, frameSize, stop_bits, wordLength, baud16x_ce, clear, rxd,
        full, empty, frameErr, overrun, parityErr, break_o, gerr, qcnt, cnt, bitStream);
input rst;
input clk;
input cyc;                              // valid bus cycle
input cs;                               // core select
input wr;                               // read reciever
output [11:0] dout;             // fifo data out
output ack;
input fifoEnable;               // enable the fifo
input fifoClear;
input clearGErr;                // clear global error
input [2:0] parityCtrl;
input [8:0] frameSize;  // frame count
input [2:0] stop_bits;
input [3:0] wordLength;
input baud16x_ce;               // baud rate clock enable
input clear;                    // clear reciever
input rxd;                              // external serial input
output full;                    // receive fifo full
output empty;           // receiver fifo is empty
output frameErr;                // framing error
output overrun;                 // receiver overrun
output parityErr;               // parity error
output break_o;                 // break detected
output gerr;                    // global error indicator
output [5:0] qcnt;              // count of number of words queued
output [10:0] cnt;              // receiver counter
output bitStream;               // received bit stream
 
//0 - simple sampling at middle of symbol period
//>0 - sampling of 3 middle ticks of sumbol perion and results as majority
parameter SamplerStyle = 0;
 
 
reg overrun;
reg [10:0] cnt;                 // sample bit rate counter / timeout counter
reg [14:0] rx_data;             // working receive data register
reg [13:0] t4;                  // data minus stop bit(s)
reg [11:0] t3;                  // data minus parity bit and start bit
reg [11:0] t5;
reg [3:0] shft_amt;
reg p1;
reg gerr;                               // global error status
reg perr;                               // parity error
reg ferr = 1'b0;                                // framing error
wire bz;                                // break detected
reg state;                              // state machine
reg wf;                                 // fifo write
wire empty;
reg didRd;
wire [11:0] dout1;
reg full1;
wire fifoFull, fifoEmpty;
 
ack_gen #(
        .READ_STAGES(1),
        .WRITE_STAGES(0),
        .REGISTER_OUTPUT(1)
) uag1
(
        .rst_i(rst),
        .clk_i(clk),
        .ce_i(1'b1),
        .i(cs & cyc & ~wr),
        .we_i(cs & cyc & wr),
        .o(ack),
        .rid_i(0),
        .wid_i(0),
        .rid_o(),
        .wid_o()
);
 
wire pe_rd, pe_wf;
edge_det ued1 (.rst(rst), .clk(clk), .ce(1'b1), .i(cs & cyc & ~wr), .pe(pe_rd), .ne(), .ee());
edge_det ued2 (.rst(rst), .clk(clk), .ce(1'b1), .i(wf), .pe(pe_wf), .ne(), .ee());
 
assign bitStream = rx_data[14];
assign bz = t3==12'd0;
wire rdf = fifoEnable ? pe_rd : pe_wf;
 
// Distributed RAM fifo (vendor supplied):
//      First word fall-through
//      64 entries deep
//      15 bits wide
uart6551RxFifo uf1
(
        .clk(clk),
        .srst(rst|clear|fifoClear),
        .wr_en(wf),
        .rd_en(rdf),
        .din({bz,perr,ferr,t3}),
        .dout({break_o,parityErr,frameErr,dout1}),
        .data_count(qcnt),
        .full(fifoFull),
        .empty(fifoEmpty)
);
 
assign dout = fifoEnable ? dout1 : t5;
assign empty = fifoEnable ? fifoEmpty : ~full1;
assign full = fifoEnable ? fifoFull : full1;
 
// compute 1/2 the length of the last bit
// needed for framing error detection
reg [8:0] halfLastBit;
always_ff @(posedge clk)
if (stop_bits==3'd3)    // 1.5 stop bits ?
        halfLastBit <= 9'd8;
else
        halfLastBit <= 9'd16;
 
reg [8:0] fhb;
always_ff @(posedge clk)
  fhb <= frameSize-halfLastBit;
 
// record a global error status
always_ff @(posedge clk)
if (rst)
        gerr <= 0;
else begin
        if (clearGErr)
                gerr <= perr | ferr | bz;
        else
                gerr <= gerr | perr | ferr | bz;
end
 
 
// right align data for word length, strip start bit
// depending on the word length, the first few bits in the
// recieve shift register will be invalid because the shift
// register shifts from MSB to LSB and shorter frames
// won't shift as far towards the LSB.
always_ff @(posedge clk)
        shft_amt <= (5'd16 - (wordLength + ({stop_bits[3],~stop_bits[3]}) + parityCtrl[0]));
always_comb
        t4 <= rx_data >> shft_amt;
 
// grab the parity bit
// Note the data is right aligned
always_comb
        p1 <= t4[wordLength];
 
// strip off parity, stop
integer n2;
always_comb
        for (n2 = 0; n2 < 12; n2 = n2 + 1)
                if (n2 < wordLength)
                        t3[n2] <= t4[n2];
                else
                        t3[n2] <= 1'b0;
 
// detect a parity err
always_comb begin
        case (parityCtrl)
        3'b001: perr <= p1 != ~^t3;     // odd parity
        3'b011: perr <= p1 != ^t3;      // even parity
        default: perr <= 0;
        endcase
end
 
 
// Three stage synchronizer to synchronize incoming data to
// the local clock (avoids metastability).
 
reg [5:0] rxdd          /* synthesis ramstyle = "logic" */; // synchronizer flops
reg rxdsmp;             // majority samples
reg rdxstart;           // for majority style sample solid 3tik-wide sample
reg [1:0] rxdsum [0:1];
always_ff @(posedge clk)
if (baud16x_ce) begin
        rxdd <= {rxdd[4:0],rxd};
  if (SamplerStyle == 0) begin
    rxdsmp <= rxdd[3];
    rdxstart <= rxdd[4]&~rxdd[3];
  end
  else begin
    rxdsum[1] <= rxdsum[0];
    rxdsum[0] <= {1'b0,rxdd[3]} + {1'b0,rxdd[4]} + {1'b0,rxdd[5]};
    rxdsmp <= rxdsum[1] > 2'd1;
    rdxstart <= (rxdsum[0] == 2'b00) & (rxdsum[1] == 2'b11);
  end
end
 
 
always_ff @(posedge clk)
if (rst)
        state <= `IDLE;
else begin
        if (clear)
                state <= `IDLE;
        else if (baud16x_ce) begin
                case (state)
                // Sit in the idle state until a start bit is
                // detected.
                `IDLE:
                        if (rdxstart)
                                state <= `CNT;
                `CNT:
                        begin
                                // Switch back to the idle state a little
                                // bit too soon.
                                if (cnt[8:2]==frameSize[8:2])
                                        state <= `IDLE;
                                // On start bit check make sure the start
                                // bit is low, otherwise go back to the
                                // idle state because it's a false start.
                                if (cnt[8:0]==8'h07) begin
                                        if (rxdsmp)
                                                state <= `IDLE;
                                end
                        end
                endcase
        end
end
 
always_ff @(posedge clk)
if (rst)
        cnt <= 9'h00;
else begin
        if (clear)
                cnt <= 9'h00;
        else if (baud16x_ce) begin
                cnt <= cnt + 2'h1;
                case (state)
                `IDLE:
                        begin
                                // reset counter on read of reciever
                                // (resets timeout count).
                                if (didRd)
                                        cnt <= 9'h0;
                                if (rdxstart)
                                        cnt <= 9'h0;
                        end
                default:        ;
                endcase
        end
end
 
always_ff @(posedge clk)
if (rst)
        wf <= 1'b0;
else begin
        // Clear write flag
        wf <= 1'b0;
        if (baud16x_ce) begin
                case (state)
                `CNT:
                        // End of the frame ?
                        // - write data to fifo
                        if (cnt[8:0]==fhb) begin
                                if (!full)
                                        wf <= 1'b1;
                        end
                default:        ;
                endcase
        end
end
 
always_ff @(posedge clk)
if (rst)
        t5 <= 1'b0;
else begin
        if (pe_wf)
                t5 <= t3;
end
 
always_ff @(posedge clk)
if (rst)
        full1 <= 1'b0;
else begin
        if (pe_wf)
                full1 <= 1'b1;
        else if (pe_rd)
                full1 <= 1'b0;
end
 
always_ff @(posedge clk)
if (rst)
        didRd <= 1'b0;
else begin
        // set a read flag for later reference
        if (pe_rd)
                didRd <= 1'b1;
        if (clear)
                didRd <= 1'b0;
        else if (baud16x_ce) begin
                case (state)
                `IDLE:
                        begin
                                if (didRd)
                                        didRd <= 1'b0;
                                if (rdxstart)
                                        didRd <= 1'b0;
                        end
                default:        ;
                endcase
        end
end
 
always_ff @(posedge clk)
if (rst)
        rx_data <= 15'h0;
else begin
        if (clear)
                rx_data <= 15'h0;
        else if (baud16x_ce) begin
                case (state)
                `CNT:
                        begin
                                //if (cnt[7:2]==frameSize[7:2])
                                //      rx_data <= 11'h0;
                                if (cnt[3:0]==4'h7)
                                        rx_data <= {rxdsmp,rx_data[14:1]};
                        end
                default:        ;
                endcase
        end
end
 
// Overrun: trying to recieve data when recieve buffer is already full.
always_ff @(posedge clk)
if (rst)
        overrun <= 1'b0;
else begin
        if (!full)
                overrun <= 1'b0;
        if (clear)
                overrun <= 1'b0;
        else if (baud16x_ce) begin
                case (state)
                `CNT:
                        if (cnt[8:0]==fhb) begin
                                if (full)
                                        overrun <= 1'b1;
                        end
                default:        ;
                endcase
        end
end
 
always_ff @(posedge clk)
if (rst)
        ferr <= 1'b0;
else begin
        if (clear)
                ferr <= 1'b0;
        else if (baud16x_ce) begin
                case (state)
                `CNT:
                        if (cnt[8:0]==fhb)
                                ferr <= ~rxdsmp;
                default:        ;
                endcase
        end
end
 
endmodule
 

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Subversion Repositories uart6551

[/] [uart6551/] [trunk/] [trunk/] [rtl/] [uart6551Rx_x12.sv] - Blame information for rev 6

Line No.	Rev	Author	Line
1	5	robfinch	`// ============================================================================`
2			`// __`
3			`// \\__/ o\ (C) 2005-2022 Robert Finch, Waterloo`
4			`// \ __ / All rights reserved.`
5			`// \/_// robfinch@finitron.ca`
6			`// \|\|`
7			`//`
8			`//`
9			`// BSD 3-Clause License`
10			`// Redistribution and use in source and binary forms, with or without`
11			`// modification, are permitted provided that the following conditions are met:`
12			`//`
13			`// 1. Redistributions of source code must retain the above copyright notice, this`
14			`// list of conditions and the following disclaimer.`
15			`//`
16			`// 2. Redistributions in binary form must reproduce the above copyright notice,`
17			`// this list of conditions and the following disclaimer in the documentation`
18			`// and/or other materials provided with the distribution.`
19			`//`
20			`// 3. Neither the name of the copyright holder nor the names of its`
21			`// contributors may be used to endorse or promote products derived from`
22			`// this software without specific prior written permission.`
23			`//`
24			`// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"`
25			`// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
26			`// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE`
27			`// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE`
28			`// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
29			`// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR`
30			`// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER`
31			`// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,`
32			`// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE`
33			`// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.`
34			`//`
35			`// ============================================================================`
36			`//`
37			`define IDLE 0
38			`define CNT 1
39
40			`module uart6551Rx_x12(rst, clk,`
41			`cyc, cs, wr, dout, ack,`
42			`fifoEnable, fifoClear, clearGErr,`
43			`parityCtrl, frameSize, stop_bits, wordLength, baud16x_ce, clear, rxd,`
44			`full, empty, frameErr, overrun, parityErr, break_o, gerr, qcnt, cnt, bitStream);`
45			`input rst;`
46			`input clk;`
47			`input cyc; // valid bus cycle`
48			`input cs; // core select`
49			`input wr; // read reciever`
50			`output [11:0] dout; // fifo data out`
51			`output ack;`
52			`input fifoEnable; // enable the fifo`
53			`input fifoClear;`
54			`input clearGErr; // clear global error`
55			`input [2:0] parityCtrl;`
56			`input [8:0] frameSize; // frame count`
57			`input [2:0] stop_bits;`
58			`input [3:0] wordLength;`
59			`input baud16x_ce; // baud rate clock enable`
60			`input clear; // clear reciever`
61			`input rxd; // external serial input`
62			`output full; // receive fifo full`
63			`output empty; // receiver fifo is empty`
64			`output frameErr; // framing error`
65			`output overrun; // receiver overrun`
66			`output parityErr; // parity error`
67			`output break_o; // break detected`
68			`output gerr; // global error indicator`
69	6	robfinch	`output [5:0] qcnt; // count of number of words queued`
70	5	robfinch	`output [10:0] cnt; // receiver counter`
71			`output bitStream; // received bit stream`
72
73			`//0 - simple sampling at middle of symbol period`
74			`//>0 - sampling of 3 middle ticks of sumbol perion and results as majority`
75			`parameter SamplerStyle = 0;`
76
77
78			`reg overrun;`
79			`reg [10:0] cnt; // sample bit rate counter / timeout counter`
80			`reg [14:0] rx_data; // working receive data register`
81			`reg [13:0] t4; // data minus stop bit(s)`
82			`reg [11:0] t3; // data minus parity bit and start bit`
83			`reg [11:0] t5;`
84			`reg [3:0] shft_amt;`
85			`reg p1;`
86			`reg gerr; // global error status`
87			`reg perr; // parity error`
88			`reg ferr = 1'b0; // framing error`
89			`wire bz; // break detected`
90			`reg state; // state machine`
91			`reg wf; // fifo write`
92			`wire empty;`
93			`reg didRd;`
94			`wire [11:0] dout1;`
95			`reg full1;`
96			`wire fifoFull, fifoEmpty;`
97
98	6	robfinch	`ack_gen #(`
99			`.READ_STAGES(1),`
100			`.WRITE_STAGES(0),`
101			`.REGISTER_OUTPUT(1)`
102			`) uag1`
103			`(`
104			`.rst_i(rst),`
105			`.clk_i(clk),`
106			`.ce_i(1'b1),`
107			`.i(cs & cyc & ~wr),`
108			`.we_i(cs & cyc & wr),`
109			`.o(ack),`
110			`.rid_i(0),`
111			`.wid_i(0),`
112			`.rid_o(),`
113			`.wid_o()`
114			`);`
115
116	5	robfinch	`wire pe_rd, pe_wf;`
117	6	robfinch	`edge_det ued1 (.rst(rst), .clk(clk), .ce(1'b1), .i(cs & cyc & ~wr), .pe(pe_rd), .ne(), .ee());`
118	5	robfinch	`edge_det ued2 (.rst(rst), .clk(clk), .ce(1'b1), .i(wf), .pe(pe_wf), .ne(), .ee());`
119
120			`assign bitStream = rx_data[14];`
121			`assign bz = t3==12'd0;`
122			`wire rdf = fifoEnable ? pe_rd : pe_wf;`
123
124	6	robfinch	`// Distributed RAM fifo (vendor supplied):`
125			`// First word fall-through`
126			`// 64 entries deep`
127			`// 15 bits wide`
128			`uart6551RxFifo uf1`
129	5	robfinch	`(`
130			`.clk(clk),`
131	6	robfinch	`.srst(rst\|clear\|fifoClear),`
132			`.wr_en(wf),`
133			`.rd_en(rdf),`
134	5	robfinch	`.din({bz,perr,ferr,t3}),`
135			`.dout({break_o,parityErr,frameErr,dout1}),`
136	6	robfinch	`.data_count(qcnt),`
137	5	robfinch	`.full(fifoFull),`
138			`.empty(fifoEmpty)`
139			`);`
140
141			`assign dout = fifoEnable ? dout1 : t5;`
142			`assign empty = fifoEnable ? fifoEmpty : ~full1;`
143			`assign full = fifoEnable ? fifoFull : full1;`
144
145			`// compute 1/2 the length of the last bit`
146			`// needed for framing error detection`
147			`reg [8:0] halfLastBit;`
148			`always_ff @(posedge clk)`
149			`if (stop_bits==3'd3) // 1.5 stop bits ?`
150			`halfLastBit <= 9'd8;`
151			`else`
152			`halfLastBit <= 9'd16;`
153
154			`reg [8:0] fhb;`
155			`always_ff @(posedge clk)`
156			`fhb <= frameSize-halfLastBit;`
157
158			`// record a global error status`
159			`always_ff @(posedge clk)`
160			`if (rst)`
161			`gerr <= 0;`
162			`else begin`
163			`if (clearGErr)`
164			`gerr <= perr \| ferr \| bz;`
165			`else`
166			`gerr <= gerr \| perr \| ferr \| bz;`
167			`end`
168
169
170			`// right align data for word length, strip start bit`
171			`// depending on the word length, the first few bits in the`
172			`// recieve shift register will be invalid because the shift`
173			`// register shifts from MSB to LSB and shorter frames`
174			`// won't shift as far towards the LSB.`
175			`always_ff @(posedge clk)`
176			`shft_amt <= (5'd16 - (wordLength + ({stop_bits[3],~stop_bits[3]}) + parityCtrl[0]));`
177			`always_comb`
178			`t4 <= rx_data >> shft_amt;`
179
180			`// grab the parity bit`
181			`// Note the data is right aligned`
182			`always_comb`
183			`p1 <= t4[wordLength];`
184
185			`// strip off parity, stop`
186			`integer n2;`
187			`always_comb`
188			`for (n2 = 0; n2 < 12; n2 = n2 + 1)`
189			`if (n2 < wordLength)`
190			`t3[n2] <= t4[n2];`
191			`else`
192			`t3[n2] <= 1'b0;`
193
194			`// detect a parity err`
195			`always_comb begin`
196			`case (parityCtrl)`
197			`3'b001: perr <= p1 != ~^t3; // odd parity`
198			`3'b011: perr <= p1 != ^t3; // even parity`
199			`default: perr <= 0;`
200			`endcase`
201			`end`
202
203
204			`// Three stage synchronizer to synchronize incoming data to`
205			`// the local clock (avoids metastability).`
206
207			`reg [5:0] rxdd /* synthesis ramstyle = "logic" */; // synchronizer flops`
208			`reg rxdsmp; // majority samples`
209			`reg rdxstart; // for majority style sample solid 3tik-wide sample`
210			`reg [1:0] rxdsum [0:1];`
211			`always_ff @(posedge clk)`
212			`if (baud16x_ce) begin`
213			`rxdd <= {rxdd[4:0],rxd};`
214			`if (SamplerStyle == 0) begin`
215			`rxdsmp <= rxdd[3];`
216			`rdxstart <= rxdd[4]&~rxdd[3];`
217			`end`
218			`else begin`
219			`rxdsum[1] <= rxdsum[0];`
220			`rxdsum[0] <= {1'b0,rxdd[3]} + {1'b0,rxdd[4]} + {1'b0,rxdd[5]};`
221			`rxdsmp <= rxdsum[1] > 2'd1;`
222			`rdxstart <= (rxdsum[0] == 2'b00) & (rxdsum[1] == 2'b11);`
223			`end`
224			`end`
225
226
227			`always_ff @(posedge clk)`
228			`if (rst)`
229			state <= `IDLE;
230			`else begin`
231			`if (clear)`
232			state <= `IDLE;
233			`else if (baud16x_ce) begin`
234			`case (state)`
235			`// Sit in the idle state until a start bit is`
236			`// detected.`
237			`IDLE:
238			`if (rdxstart)`
239			state <= `CNT;
240			`CNT:
241			`begin`
242			`// Switch back to the idle state a little`
243			`// bit too soon.`
244			`if (cnt[8:2]==frameSize[8:2])`
245			state <= `IDLE;
246			`// On start bit check make sure the start`
247			`// bit is low, otherwise go back to the`
248			`// idle state because it's a false start.`
249			`if (cnt[8:0]==8'h07) begin`
250			`if (rxdsmp)`
251			state <= `IDLE;
252			`end`
253			`end`
254			`endcase`
255			`end`
256			`end`
257
258			`always_ff @(posedge clk)`
259			`if (rst)`
260			`cnt <= 9'h00;`
261			`else begin`
262			`if (clear)`
263			`cnt <= 9'h00;`
264			`else if (baud16x_ce) begin`
265			`cnt <= cnt + 2'h1;`
266			`case (state)`
267			`IDLE:
268			`begin`
269			`// reset counter on read of reciever`
270			`// (resets timeout count).`
271			`if (didRd)`
272			`cnt <= 9'h0;`
273			`if (rdxstart)`
274			`cnt <= 9'h0;`
275			`end`
276			`default: ;`
277			`endcase`
278			`end`
279			`end`
280
281			`always_ff @(posedge clk)`
282			`if (rst)`
283			`wf <= 1'b0;`
284			`else begin`
285			`// Clear write flag`
286			`wf <= 1'b0;`
287			`if (baud16x_ce) begin`
288			`case (state)`
289			`CNT:
290			`// End of the frame ?`
291			`// - write data to fifo`
292			`if (cnt[8:0]==fhb) begin`
293			`if (!full)`
294			`wf <= 1'b1;`
295			`end`
296			`default: ;`
297			`endcase`
298			`end`
299			`end`
300
301			`always_ff @(posedge clk)`
302			`if (rst)`
303			`t5 <= 1'b0;`
304			`else begin`
305			`if (pe_wf)`
306			`t5 <= t3;`
307			`end`
308
309			`always_ff @(posedge clk)`
310			`if (rst)`
311			`full1 <= 1'b0;`
312			`else begin`
313			`if (pe_wf)`
314			`full1 <= 1'b1;`
315			`else if (pe_rd)`
316			`full1 <= 1'b0;`
317			`end`
318
319			`always_ff @(posedge clk)`
320			`if (rst)`
321			`didRd <= 1'b0;`
322			`else begin`
323			`// set a read flag for later reference`
324			`if (pe_rd)`
325			`didRd <= 1'b1;`
326			`if (clear)`
327			`didRd <= 1'b0;`
328			`else if (baud16x_ce) begin`
329			`case (state)`
330			`IDLE:
331			`begin`
332			`if (didRd)`
333			`didRd <= 1'b0;`
334			`if (rdxstart)`
335			`didRd <= 1'b0;`
336			`end`
337			`default: ;`
338			`endcase`
339			`end`
340			`end`
341
342			`always_ff @(posedge clk)`
343			`if (rst)`
344			`rx_data <= 15'h0;`
345			`else begin`
346			`if (clear)`
347			`rx_data <= 15'h0;`
348			`else if (baud16x_ce) begin`
349			`case (state)`
350			`CNT:
351			`begin`
352			`//if (cnt[7:2]==frameSize[7:2])`
353			`// rx_data <= 11'h0;`
354			`if (cnt[3:0]==4'h7)`
355			`rx_data <= {rxdsmp,rx_data[14:1]};`
356			`end`
357			`default: ;`
358			`endcase`
359			`end`
360			`end`
361
362			`// Overrun: trying to recieve data when recieve buffer is already full.`
363			`always_ff @(posedge clk)`
364			`if (rst)`
365			`overrun <= 1'b0;`
366			`else begin`
367			`if (!full)`
368			`overrun <= 1'b0;`
369			`if (clear)`
370			`overrun <= 1'b0;`
371			`else if (baud16x_ce) begin`
372			`case (state)`
373			`CNT:
374			`if (cnt[8:0]==fhb) begin`
375			`if (full)`
376			`overrun <= 1'b1;`
377			`end`
378			`default: ;`
379			`endcase`
380			`end`
381			`end`
382
383			`always_ff @(posedge clk)`
384			`if (rst)`
385			`ferr <= 1'b0;`
386			`else begin`
387			`if (clear)`
388			`ferr <= 1'b0;`
389			`else if (baud16x_ce) begin`
390			`case (state)`
391			`CNT:
392			`if (cnt[8:0]==fhb)`
393			`ferr <= ~rxdsmp;`
394			`default: ;`
395			`endcase`
396			`end`
397			`end`
398
399			`endmodule`
400