关于FPGA的DS18B20模块的时序问题，感觉一点错都没有啊。。。。

ubeautqq

求大神指导一下到底哪里错了，已经调试了三四天了，不管怎么调temp的值都是0.。。

module DS18B20
2 n# ?, n! d5 t. y, S+ M$ Y(
# i' e+ l( G) |2 a( M9 ^" ~; ECLK48M,
) N' v" \3 n  I3 T: e. }% j1 I6 R//RST,
* u1 T0 ]8 U! T' I4 N# cDQ,
temp
);
//Port declaration
input CLK48M;
//input RST;
7 z, Y& O, P3 q- ]1 @* L% kinout DQ;
output [11:0] temp;

reg [7:0] Cnt;
reg clk1MHz;

always@(posedge CLK48M)
begin
6 }1 r4 Q5 t0 a4 ~; pif(Cnt==8'd23)
begin
Cnt<=8'd0;
clk1MHz<=~clk1MHz;
end
else
" H- P! N* v4 n% WCnt<=Cnt+8'd1;
4 ?( r5 f4 l' ^4 @/ L3 Pend

2 i  c" W7 H! Y4 lparameter IDLE = 11'b000_0000_0001,
DO_RESET = 11'b000_0000_0010,
CMD_CC = 11'b000_0000_0100,
CMD_44 = 11'b000_0000_1000,
6 A! `+ H; l& u+ b" Z9 ?$ ZCMD_BE = 11'b000_0001_0000,
, l) I2 f2 H) p) B7 B% EWRITE_BYTE = 11'b000_0010_0000,
+ Z5 L& P, }3 `1 }7 a- WWrite_High = 11'b000_0100_0000,
6 \. b$ \: k( `8 f1 ~% l8 h2 bWrite_Low = 11'b000_1000_0000,
WAIT_750ms = 11'b001_0000_0000,
/ Z, h3 P7 _0 d8 F* cREAD_BIT = 11'b010_0000_0000,
1 M* U: N- N% s% i. F# tGET_TMP = 11'b100_0000_0000,
' S  X# K/ v3 T9 fWAIT_4MS = 11'b100_1000_1000;
& x$ ~0 [2 W' P//-------------------------------------------------------------------
reg [10:0] state;
, S, ]1 L& N8 m2 xreg [31:0] counter;
reg DQ;
) u- i! C- o) s4 [# mreg [7:0] write_byte;//中间寄存器,保存主机要写的指令字节
reg [3:0] write_byte_cnt;
reg [1:0] byte_flag;
1 w4 S9 ~( T) `7 @* Qreg [3:0] read_bit;
6 e. c; a* S& u0 u+ \# Greg[11:0] temp;//12位温度数据
$ b" s2 f7 B- t9 A) e: oreg TMP_bit;

always@(posedge clk1MHz)
begin
4 V' @8 l% x! `/ [. J6 _case(state)
$ k* `' _( h, {3 QIDLE:
+ }" d$ t/ B0 }) }begin
2 q0 M+ \; x" s+ CDQ<=1'bz;//空闲状态释放数据总线,由外接上拉电阻将DQ数据线置高
counter<=0;
* c+ A, V  c! x7 r8 P9 v" K: p$ vwrite_byte_cnt<=4'b0000;
byte_flag<=2'b00;
read_bit<=4'b0;
! J0 [2 S8 J9 Q6 Jstate<=DO_RESET;
end
DO_RESET://主机拉低数据总线持续至少480us，然后释放总线
4 }8 o2 ]" d+ z7 O2 J- k- N2 S9 Xbegin
; t4 v$ C1 y( V, c7 d, Wif(counter<=480)
begin
) I8 Z% J' a7 L2 Q1 n* gDQ<=1'b0;//拉低数据线480us
counter<=counter+1'b1;
; f/ K3 q7 [4 S  y& J5 zend
else if(counter>480 && counter<=780)
begin
DQ<=1'bz;//释放数据总线60us+240us=300us
counter<=counter+1'b1;
0 U& P1 }3 C6 A& jif(DQ)//检测从机是否发送Presence Pulse(持续60us~240us低电平)
begin
state<=CMD_CC;
counter<=0;
0 c& r5 Z& v8 a3 x  \end
else
begin
state<=IDLE;
end
end
& x/ O0 i' x9 b( uend
CMD_CC:
begin
write_byte<=8'hCC;
$ |7 [6 b* j3 E) N: G/ Vstate<=WRITE_BYTE;
end
# A9 c* b# p- ^0 q5 y. ^: UWRITE_BYTE://写指令字节,由低位向高位依次写入从机
$ ^/ }4 D* j! x6 _+ [2 I# Sbegin
2 }5 M/ }9 @) E" u, A' @case(write_byte_cnt)
- i0 t+ o- m0 L9 a$ j" d4'b0000:
5 [; I. Y* Z) z0 r5 h( o% Y0 g6 ?3 Qbegin
state<=write_byte[0]?Write_High:Write_Low;
write_byte_cnt<=write_byte_cnt+1'b1;
8 z; ~! M3 X+ I0 m5 c* o# k2 E: }+ vend
4'b0001:
begin
state<=write_byte[1]?Write_High:Write_Low;
6 j1 {0 N$ `0 [7 v; f6 Twrite_byte_cnt<=write_byte_cnt+1'b1;
end
4'b0010:
! @- c$ `* T8 B/ Y" F3 K$ sbegin
state<=write_byte[2]?Write_High:Write_Low;
write_byte_cnt<=write_byte_cnt+1'b1;
end
4'b0011:
! }" I; y2 F3 `begin
6 ~2 o2 g3 D5 I/ @# w; f  S0 lstate<=write_byte[3]?Write_High:Write_Low;
: m( |7 Q$ t3 N3 kwrite_byte_cnt<=write_byte_cnt+1'b1;
% l+ J" X6 J0 Pend
4'b0100:
1 ]1 {6 g  p" ?0 ]begin
" L- y) {% m8 X! w5 u! K! dstate<=write_byte[4]?Write_High:Write_Low;
4 Z% F3 N6 i# owrite_byte_cnt<=write_byte_cnt+1'b1;
end
" E% ^6 B; d8 Q+ u, j0 l5 h- I4'b0101:
begin
2 {8 ^3 z" U4 d3 I) v( ^state<=write_byte[5]?Write_High:Write_Low;
write_byte_cnt<=write_byte_cnt+1'b1;
end
4'b0110:
begin
state<=write_byte[6]?Write_High:Write_Low;
$ P9 O8 Y$ z$ z& U1 g( qwrite_byte_cnt<=write_byte_cnt+1'b1;
end
4'b0111:
begin
state<=write_byte[7]?Write_High:Write_Low;
write_byte_cnt<=write_byte_cnt+1'b1;
end
4'b1000://8bit字节写完后在此处进行状态转换
( v1 j9 X7 G; @' G' Lbegin
; T3 D1 ~6 u# h1 Y! |% r1 F  @write_byte_cnt<=4'b0000;
6 i$ |2 I5 Z6 C8 V, kcase(byte_flag)
2'b00:
begin
9 B: I, B  l- U" [: Tstate<=CMD_44;
byte_flag<=2'b01;
end
  h9 M- _8 X3 I8 D2 t2'b01:
begin
state<=DO_RESET;
byte_flag<=2'b10;
end
5 h/ t$ p7 L8 ?+ I2'b10:
. A9 z% i8 b0 z% B+ |- jbegin
( e5 D, t$ P. X  Z: Rstate<=CMD_BE;
6 t$ L! r" F; m( u% D* |. bbyte_flag<=2'b11;
% M. I! H: D9 Q7 @( v/ e  A6 _end
  Q$ x, s# `% q# C* s! V1 C- M: `( L2'b11:
begin
2 N* M, M# u' I* M8 Cstate<=GET_TMP;
- e1 ~4 T2 H: |; }% P8 [2 l' J, Ebyte_flag<=2'b00;
end
endcase
end
default:write_byte_cnt<=4'b0000;
- m) a( k! j/ gendcase
end
Write_High://写‘1’时序:主机拉低数据线1~27us,然后释放数据总线30~数千us.
+ E: C7 K4 ?+ l# Gbegin
, B- ^; h: r5 ]; j; y6 O$ Qif(counter<=8)//拉低数据线15us(至少1us)
begin
DQ<=1'b0;
5 Z* w( R! G# u2 H& x3 k! Pcounter<=counter+1'b1;
end
else if(counter>8 && counter begin
DQ counter end
else
2 R' B/ ]( o6 h' g2 ?begin
counter state end
) Z/ |6 {6 l+ ?# K' `' m# Jend
Write_Low://写‘0’时序:主机拉低数据线30~227us,然后释放数据总线1us~数千us.
begin
if(counter begin
4 n7 {$ D4 o7 ~, j( Q7 eDQ counter end
: U, Q6 {( H5 @  e7 p$ k; H: belse if(counter>78 && counter begin
DQ counter end
else
7 ], b' h9 u& qbegin
counter state end
; \* v' K0 o: [/ ~end
. U4 w  l2 U0 ]3 NCMD_44:
begin
- J3 q/ ~* `) p5 kwrite_byte state end
2 j" U6 n9 n2 t6 _WAIT_750ms:
; J' z% o. s% x; lbegin
if(counter>750000)//实际上只等待几us甚至不等待也可以
begin
state<=DO_RESET;
counter<=0;
9 e* h' _  [  K- v0 N& jend
else
" X/ c0 ?+ Y  R- xcounter<=counter+1'b1;
end
4 }0 C8 ^0 \, z! d* @7 R9 JCMD_BE:
begin
write_byte<=8'hBE;
7 \9 H& s" Q/ I6 @) u5 [5 V3 Qstate<=WRITE_BYTE;
end
GET_TMP:
begin
  C3 N9 S6 y2 C* ycase(read_bit)
4'h0:
& {- D' ]& B5 G: s# q- I$ q* {begin
state<=READ_BIT;
read_bit<=read_bit+1'b1;
) O7 ]. z# B6 [% l- j: Pend
4'h1:
begin
state<=READ_BIT;
4 L& S; \, F0 d" E- E& a0 Kread_bit<=read_bit+1'b1;
temp[0]<=TMP_bit;
end
4'h2:
begin
# b4 s5 L! l* S, I) O4 Ustate<=READ_BIT;
read_bit<=read_bit+1'b1;
temp[1]<=TMP_bit;
end
4'h3:
begin
state<=READ_BIT;
read_bit<=read_bit+1'b1;
temp[2]<=TMP_bit;
* G3 ^: d& N1 l$ V; yend
, I$ w* y7 U$ C; U$ y+ ]4'h4:
begin
3 i, s6 _0 A3 H1 y1 V; m0 j+ Estate<=READ_BIT;
read_bit<=read_bit+1'b1;
( i  W( j" X& X. z/ g0 T( r6 E9 S8 Ntemp[3]<=TMP_bit;
; v* Z  M/ _$ s# v% hend
4'h5:
begin
# x) V) c+ i; ~% P' G6 W/ I1 qstate<=READ_BIT;
6 C- u; J" Y. I/ }; z; u- ?( bread_bit<=read_bit+1'b1;
0 j* C; z! ^7 Q0 u7 `temp[4]<=TMP_bit;
end
" [5 k/ ^1 e2 Y( X4'h6:
begin
state<=READ_BIT;
read_bit<=read_bit+1'b1;
temp[5]<=TMP_bit;
end
( M" \' h: S7 `/ u4'h7:
0 ~8 o+ Y9 E: p/ rbegin
state<=READ_BIT;
; d" E. L$ r: x- sread_bit<=read_bit+1'b1;
temp[6]<=TMP_bit;
end
' t4 v% ~0 M  l/ O7 f( p4'h8:
begin
state<=READ_BIT;
: F1 B5 \, I: l5 N7 [read_bit<=read_bit+1'b1;
2 ~! r6 }( p8 p3 K5 X5 Z' T# rtemp[7]<=TMP_bit;
end
4'h9:
begin
. u! E9 f& _/ C1 d0 K2 v; W1 xstate<=READ_BIT;
; a! z1 B: q6 [5 g3 oread_bit<=read_bit+1'b1;
temp[8]<=TMP_bit;
end
- m+ i3 `7 s! {4'hA:
, f  O0 V, ^7 K. h% gbegin
. J) ~1 I9 ~, w6 h4 s* Gstate<=READ_BIT;
read_bit<=read_bit+1'b1;
temp[9]<=TMP_bit;
end
4'hB:
begin
7 ?% ^6 C) L8 Y0 R0 d) W: cstate<=READ_BIT;
read_bit<=read_bit+1'b1;
/ m7 d- R1 _2 F8 ctemp[10]<=TMP_bit;
end
! b; J/ k6 q! C/ U" {# I4'hC:
begin
( F  a, N( @, K% c( Istate<=WAIT_4MS;
read_bit<=4'h0;
temp[11]<=TMP_bit;
! z6 W! y8 o7 w# ~/ Hend
default:read_bit<=4'h0;
endcase
end
READ_BIT://读时序:主机拉低数据总线约2~4us,然后释放数据总线2~4us,再读取DQ数据线上的值
# {  |# l0 Y' B: }/ v- g+ Wbegin
if(counter>=0 && counter<=3)
begin
+ B, Q$ U/ p8 p$ {DQ<=1'b0;//主机拉低数据总线约5us
1 ^7 Z3 }" x' M; gcounter<=counter+1'b1;
end
else if(counter>=4 && counter<=7)//最迟必须在29us处释放数据线
begin
+ X( S) m, b6 N) u3 u2 }4 _; u: }DQ<=1'bz;//释放数据总线5us
/ A* {0 J4 G: x* X# Qcounter<=counter+1'b1;
end
$ x0 k. l4 O: I6 _; Aelse if(counter==8)
9 c( n$ ~4 s  n7 Rbegin
- R; G( h' k, t0 }' W3 y
/ @, e$ y5 e- P9 @counter<=counter+1'b1;
6 M7 q7 i0 U; K- X* f( n! NTMP_bit<=DQ;
end
else if(counter>=9 && counter begin
( i9 w) ~& N4 w# r, P6 g" rcounter end
9 g! U3 v' X, Q; i7 r3 Zelse
5 C9 c  P, O$ n. Abegin
4 \5 e# h  r! `: ?- z. S9 A2 a, astate counter end
end
9 w. u: l0 Z" R, S5 eWAIT_4MS:
# E5 w2 w! ^0 p4 |+ lbegin
if(counter>4000)
% Q9 Y8 Z- q7 M; b' t$ ^; ~4 Mbegin
3 b- `% c7 [. k: x' S$ ?/ mstate<=IDLE;
* a2 o& A6 i) ~counter<=0;
end
7 n! L! P$ _2 B. r) d! ~$ p* Selse
begin
- |7 `$ B# y9 tcounter<=counter+1'b1;
5 G2 y9 b4 N; f8 M1 z+ Y0 dend
/ N  _! z. s% K2 X! `3 Yend
default:state<=IDLE;
endcase

end
" B/ ~% s! ^3 R/ [  k/ }endmodule

wu68aq

你这代码也太长了吧