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發表於 2010-10-20 14:31:16
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reg [7:0] RxD_data;
* J l7 ^- |( d1 ?! `1 T$ p3 yreg [7:0] RxD_data_out;, [8 E( _; Q, c8 [
always @(posedge clk) begin! m3 [2 n: q+ M m
if(Baud8Tick && next_bit && state[3]) begin
C: z/ ~. ^! d, F) @7 ? RxD_data <= {~RxD_bit_inv, RxD_data[7:1]};/ Y# Z y& v' H, z! o+ G& `
end
7 M# R4 n7 J" R! Y5 u5 u: V if (Baud8Tick && next_bit && state==4'b0001 && ~RxD_bit_inv) begin
0 A# |8 j1 s' H* m c+ l% W& @ RxD_data_out <= RxD_data;3 }$ D0 p3 l! n
end
3 r' Q' o: c# T! ^3 `end$ p. |" z1 ?6 y) |0 R6 S3 d
+ |9 Y4 G, m1 K/ b$ p
0 i3 A& m+ b# Q' V3 T! _reg RxD_data_ready, RxD_data_error;
* Q! w" ~/ S4 V' k% wreg RxD_data_ready_in;! `! L5 [7 f1 z3 _0 v S% x
reg[0:2] count;
0 \( B& M- u9 jreg[0:2] count2;
, i' s# F( M0 Areg count1;
: z$ |6 z* U. J! D$ h/ G# h7 Y/ lalways @(posedge clk). \2 X& B( f: q- `$ O
begin
1 W# Q; S: |# Y
: I( E+ N& m9 w0 j# w4 Q% X if (Baud8Tick && next_bit && state==4'b0001 && ~RxD_bit_inv) begin, N* a* c' O8 F7 Q) l& [/ T5 g
RxD_data_ready_in <= 1'b1;& }6 m; f0 H' d4 a- ~, b% ^
count1 <= 1'b1;7 D* d) x/ A1 X5 l+ M8 M& A# d& v
count <= 3'b000;
5 h: R' A) i+ v% ~) @. s% _9 `0 r count2 <= 3'b000;
$ L9 Y1 b) I8 n! m, \& @& Q- E end % e% B9 ^; {2 B# q3 Z
else if(count==4 && count1==1 )begin
$ n; |% t) H I$ d RxD_data_ready <= 1'b0;2 S% |8 @; [2 r, k9 x
count <= 3'b000;! W7 m: ?' F& `6 {3 x, ^
count2 <= 3'b000;8 ?% c7 r* z. t' K/ h5 c5 P
count1 <= 1'b0;
# B+ y, k* }1 @9 S+ b" T end& I# o& c7 w+ H
else if(count2==4 && count1==1 ) begin
* `. y3 K ?2 g& i; G count <= count+1 ;2 t0 X+ Q8 y# J; T' I
RxD_data_ready <= RxD_data_ready_in ;& C- e$ j# z7 L- H
end
% T1 s2 P6 V0 @1 G% ] else begin
* Y; {0 z. B# v- V) G# @ Q count2 <= count2+1 ;; a. L* i+ H: C+ N2 F
RxD_data_ready <= 1'b0;
2 I- y3 C h' e4 e3 E6 I end
' M6 U! X- ]3 j8 N6 a) o2 L RxD_data_error <= (Baud8Tick && next_bit && state==4'b0001 && RxD_bit_inv); // error if the stop bit is not received" x6 A: {8 f4 [# N) a
8 \. P2 _# p% I/ ?/ Y/ t f
end: t, C# t/ |* ?
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+ O8 b' m, x* g# Y" k. o6 w+ j: ^5 K/ d
reg [4:0] gap_count;% i* @' H% ]0 F2 ?) x
always @(posedge clk)
, n/ ]/ K9 _! v% K0 E1 w# w8 e- Y if (state!=0)
6 n- i7 p3 q" i. I$ D gap_count<=0;
' L. H* T0 a T6 m/ o. u% r; L else if(Baud8Tick & ~gap_count[4]) 7 o9 E7 }6 `* b" I8 T C. \! {
gap_count <= gap_count + 1;
~, H( `1 f& Wassign RxD_idle = gap_count[4];2 H: W+ M8 C4 M. I3 R' l
reg RxD_endofpacket;
( c5 h, y' T+ |! L$ Nalways @(posedge clk)
# d* A4 b$ \# A/ RRxD_endofpacket <= Baud8Tick & (gap_count==15);
0 }6 z' j2 ?! E5 d% l! x) e) h! D* M
endmodule
7 w: b/ Z( u# ^
# ?$ X0 ]( ^ e( O; @我想知道為什麼RxD_data_ready腳在資料錯誤時還會拉成high,麻煩會的高手教教我,謝謝! |
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