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module	MDIO
(
input	rst,
input	clk,
output reg mdc,
inout	mdio,
input
start
,
//开始传输标志
高电平有效，结束传输后拉低
input
[1:0]
opcode
,
input
[4:0]
phy_addr
,
//phy address
input
[4:0]
reg_addr
,
//phy register address
input
[15:0]
write_data ,
//write smi data
output reg [15:0]
phy_reg
,
//read smi data
output reg
transfer_end
//write or read finished
);
reg mdio_oe,mdio_out;
wire mdio_in;
assign mdio = mdio_oe ? mdio_out : 1'bz ;// MDIO数据输出或高阻, 0-READ,1-WRITE
assign mdio_in = mdio;
//产生MDC 时钟
parameter NUM=49;
//50M/100=500k
reg [5:0] cnt;
always @(posedge clk or negedge rst)
begin
if(!rst)
begin
cnt<=0;
mdc<=0;
end
else if (cnt==NUM)
begin
cnt<=0;
mdc<=mdc+1;
end
else
begin
cnt<=cnt+1;
end
end
//数据流，上升沿有效
parameter preamble=8'b00000001;
parameter st=
8'b00000010;
parameter op=
8'b00000100;
parameter phyad=
8'b00001000;
parameter regad=
8'b00010000;
parameter ta=
8'b00100000;
parameter data=
8'b01000000;
parameter idle=
8'b10000000;
//检测上升沿，产生开始传输脉冲
reg start_next;
wire start_edge;
always @(posedge mdc or negedge rst)
begin
if(!rst)
begin
start_next<=0;
end
else
start_next<=start;
end
assign start_edge=!start_next & start;
//状态转移
reg [7:0] state,state_next;
always @(posedge mdc or negedge rst )
begin
if(!rst)
begin
state<=idle;
end
else if(start_edge)
begin
state<=preamble;
end
else
state<=state_next;
end
//接口数据缓存
reg [1:0] st_code;
//mdio start code
reg [1:0] ta_code ;
//mdio write code
reg [1:0] op_code;
reg [4:0] regaddr;
reg [4:0] phyaddr;
reg [15:0] writedata;
reg [7:0] counter;
always @(posedge mdc or negedge rst)
begin
if(!rst)
begin
counter<=0;
end
else if(counter==64)
begin
counter<=0;
transfer_end<=1;
end
else if(state!=idle)
begin
transfer_end<=0;
counter<=counter+1;
end
end
always @(negedge mdc)
begin
state_next<=state;
case(state)
preamble:
begin
st_code<= 2'b01 ;
ta_code<= 2'b10 ;
op_code<=opcode;//缓存
regaddr<=reg_addr;
phyaddr<=phy_addr;
writedata<=write_data;
mdio_oe<=1;
mdio_out<=1;
if(counter==31)
begin
state_next<=st;
end
end
st:
begin
mdio_oe<=1;
mdio_out<=st_code[1];
st_code<=st_code<<1;
if(counter==33)
begin
state_next<=op;
end
end
op:
begin
mdio_oe<=1;
mdio_out<=op_code[1];
op_code<=op_code<<1;
if(counter==35)
begin
state_next<=phyad;
end
end
phyad:
begin
mdio_oe<=1;
mdio_out<=phyaddr[4];
phyaddr<=phyaddr<<1;
if(counter==40)
begin
state_next<=regad;
end
end
regad:
begin
mdio_oe<=1;
mdio_out<=regaddr[4];
regaddr<=regaddr<<1;
if(counter==45)
begin
state_next<=ta;
end
end
ta:
begin
if(opcode==2'b10)
begin
mdio_oe<=0;
if(counter==47)
begin
state_next<=data;
end
end
if(opcode==2'b01)
begin
mdio_oe<=1;
mdio_out<=ta_code[1];
ta_code<=ta_code<<1;
if(counter==47)
begin
state_next<=data;
end
end
end
data:
begin
if(opcode==2'b10)//读取
begin
mdio_oe<=0;
//读取放到外面；
if(counter==63)
begin
state_next<=idle;
end
end
if(opcode==2'b01)//写入
begin
mdio_oe<=1;
mdio_out<=writedata[15];
writedata<=writedata<<1;
if(counter==63)
begin
state_next<=idle;
end
end
end
idle:
begin
mdio_oe<=0;
if(counter==64)
begin
state_next<=idle;
end
end
default:
begin
state_next<=idle;
end
endcase
end
//读取数据
always @(posedge mdc or negedge rst )
begin
if(!rst)
begin
phy_reg<=0;
end
else if(state_next==data )
begin
phy_reg<={phy_reg[14:0],mdio_in};
end
else
phy_reg<=phy_reg;
end
endmodule

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`timescale
1 ns / 1 ps
module tb;
reg
clk;
reg
rst;
wire mdc;
wire
mdio;
reg start
;
//开始传输标志
高电平有效，结束传输后拉低
reg
[1:0]
opcode
;
reg
[4:0]
phy_addr
;
//phy address
reg
[4:0]
reg_addr
;
//phy register address
reg
[15:0]
write_data ;
//write smi data
wire [15:0]
phy_reg
;
//read smi data
wire
transfer_end ;
//write or read finished
initial
begin
rst=0;
start=0;
phy_addr=5'b10101;
reg_addr=5'b01010;
opcode=2'b01;
//10 读取
01
写入
write_data=16'h5a5a;
//
mdio_data=16'ha5a5;
#10 rst=1;
clk=1;
#80 start=1;
#150000 start=0;
#4000 start=1;
#150000 start=0;
#4000 start=1;
#150000 start=0;
end
always #10 clk<=~clk;
//读取逻辑验证
//reg [15:0] mdio_data;
//reg mdio_out;
//reg mdio_en;
//
//assign mdio=mdio_en ? mdio_out : 1'bz;
//reg [7:0] counter;
//always @(posedge mdc or negedge rst)
//begin
//	if(!rst)
//	begin
//
counter<=0;
//	end
//	else if(start)
//
if(counter==64)
//
counter<=0;
//
else
//
counter <=counter+1;
//	else
//
counter<=0;
//
//end
//always @(negedge mdc)
//begin
//	case(counter)
//
48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64:
//
begin
//
mdio_en<=1;
//
mdio_out<=mdio_data[15];
//
mdio_data<={mdio_data[14:0],1'b0};
//
end
//	endcase
//end
MDIO
MDIO_INST
(
.rst(rst),
.clk(clk),
.mdc(mdc),
.mdio(mdio),
.start (start)
,
//开始传输标志
高电平有效，结束传输后拉低
.opcode
(opcode)
,
.phy_addr (phy_addr)
,
//phy address
.reg_addr (reg_addr)
,
//phy register address
.write_data (write_data),
//write smi data
.phy_reg
(phy_reg)
,
//read smi data
.transfer_end (transfer_end)
//write or read finished
);
endmodule