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發表於 2010-10-20 14:31:16
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reg [7:0] RxD_data; A* o3 \% g0 y- p+ c7 M
reg [7:0] RxD_data_out;
0 x! {4 t$ {9 N* s! Q. t; g; y, `always @(posedge clk) begin+ f/ J3 T' e6 C# H1 P
if(Baud8Tick && next_bit && state[3]) begin
( E; M( _9 y% g) _- Q RxD_data <= {~RxD_bit_inv, RxD_data[7:1]};4 p6 Q& {( O8 D- `1 o' }( G
end# H/ y" _5 M/ l' E5 E, d
if (Baud8Tick && next_bit && state==4'b0001 && ~RxD_bit_inv) begin8 A" L" n$ I& H# ?6 B
RxD_data_out <= RxD_data;
! y! H# ?( ?, o* e3 g% A end
6 Y# t8 y; j5 D+ o$ Fend
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* b$ p5 f" {+ G Ereg RxD_data_ready, RxD_data_error;* o* ?0 w6 X$ T* j/ ~0 I) C% x$ V0 _
reg RxD_data_ready_in;, S6 b$ l/ h. h9 f. l, u" Q' g
reg[0:2] count;
2 l* G5 n( T' W6 s+ Y/ s& z4 kreg[0:2] count2;" m* l3 ~+ L' g5 q+ m' V
reg count1;$ v; Y) l+ R3 h
always @(posedge clk)
) ?4 J) c# R$ dbegin5 I" a8 C4 t9 P' N* C' w
( q8 Y9 y' S9 W5 s k* r3 f* b
if (Baud8Tick && next_bit && state==4'b0001 && ~RxD_bit_inv) begin
) T( W6 I0 B0 j' m9 t- G2 Q RxD_data_ready_in <= 1'b1;/ y* p& i5 g: Y2 F3 j4 C; M, O- Z N
count1 <= 1'b1;
9 [9 E x& ?: W* F: C E' i) R count <= 3'b000;
0 A9 q9 ~0 D1 w: ~4 ?/ v( f count2 <= 3'b000;
! w1 i( {- U$ x3 W2 B: ~ end
i6 C, r3 N# s# O& F8 B. i/ y else if(count==4 && count1==1 )begin/ ~3 y- i' X: I: A, |
RxD_data_ready <= 1'b0;
1 I. d# Y" P2 _9 l. X count <= 3'b000; p2 Y( M0 o1 j# j( d* k# U
count2 <= 3'b000;
. }$ M' n4 S, j: D1 V. k count1 <= 1'b0;5 @" V, t+ A {9 A5 U
end
! Q& n6 {- L, u, a1 f& d else if(count2==4 && count1==1 ) begin+ ~' u- r; o r) ~0 T
count <= count+1 ;2 o3 \6 W* s5 M7 e4 @8 f7 u) ^
RxD_data_ready <= RxD_data_ready_in ;
$ B* E' X. g8 A9 f& s3 b end$ b2 F0 N( A$ m+ e: e g4 u/ }+ O& l
else begin8 i) x E+ B6 P, d& B. J$ I
count2 <= count2+1 ;
5 ^2 }# H# ?( B( Y: N8 D RxD_data_ready <= 1'b0;
. }% g+ u D, S) h9 h end
! m# |8 S# I# X$ q, O* g ?& `; `" D% \ RxD_data_error <= (Baud8Tick && next_bit && state==4'b0001 && RxD_bit_inv); // error if the stop bit is not received
* J8 S5 R5 E( q" C1 \
" V1 j, E, t* i2 Q9 U6 ?. j! gend ?- c) T$ a2 h; \# V. L
' L* n e4 u3 F; w& J& d
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" ]. q: r9 E6 R. a4 v& P" [reg [4:0] gap_count;6 |2 m: p" \! {4 s, u5 }! Z+ i: U
always @(posedge clk)
5 C& Y c# T# C0 c7 m8 Z3 \ `; H if (state!=0) 0 e' O0 o, S& R m! M" n/ \7 h
gap_count<=0;
6 x: A p) N: [3 D else if(Baud8Tick & ~gap_count[4])
& E: t% O- K% X, X B gap_count <= gap_count + 1;
. a. F- N- v5 g1 j# q D. y9 Bassign RxD_idle = gap_count[4];9 m/ j7 F1 X8 S/ l6 Y* F! X
reg RxD_endofpacket;
4 q+ m4 {9 Y$ Calways @(posedge clk) " @: g( }% }; u. f/ ~
RxD_endofpacket <= Baud8Tick & (gap_count==15);% h) W2 Z5 ]+ p2 H5 }
) R t, {; Z+ {5 S5 [! Z4 G
endmodule& ?5 q* w1 b% a1 A/ i" f
& U2 s a8 ?% _) `5 K+ e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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