FPGA模块——以太网MDIO读写
- MDIO接口介绍
- MDIO接口代码
- （1）MDIO接口驱动代码
- （2）使用MDIO驱动的代码
MDIO接口介绍
MDIO是串行管理接口。MAC 和 PHY 芯片有一个配置接口，即 MDIO 接口，可以配置 PHY 芯片的工作模式以及获取 PHY 芯片的若干状态信息。
1.MDIO部分的接口结构
2.千兆以太网在接口上兼容百兆和十兆以太网。
3.YT8511 是一个千兆以太网物理层收发器，支持 1000/100/10Mbps 通信速率，该芯片内部的参数可以通过MDIO接口进行配置。
MDIO接口代码
MDIO接口主要是控制三根接口线，进行驱动和读写。
（1）MDIO接口驱动代码
mdio_dri文件：输入一些读写开始等等控制信号，输出读到的数据和控制芯片的时钟
module mdio_dri #(
parameter PHY_ADDR = 5'b00100,//PHY地址
parameter CLK_DIV = 6'd10 //分频系数
)
(
input clk , //时钟信号
input rst_n , //复位信号,低电平有效
input op_exec , //触发开始信号
input op_rh_wl , //低电平写，高电平读
input [4:0] op_addr , //寄存器地址
input [15:0] op_wr_data, //写入寄存器的数据
output reg op_done , //读写完成
output reg [15:0] op_rd_data, //读出的数据
output reg op_rd_ack , //读应答信号 0:应答 1:未应答
output reg dri_clk , //驱动时钟
output reg eth_mdc , //PHY管理接口的时钟信号
inout eth_mdio //PHY管理接口的双向数据信号
);
//parameter define
localparam st_idle = 6'b00_0001; //空闲状态
localparam st_pre = 6'b00_0010; //发送PRE(前导码)
localparam st_start = 6'b00_0100; //开始状态,发送ST(开始)+OP(操作码)
localparam st_addr = 6'b00_1000; //写地址,发送PHY地址+寄存器地址
localparam st_wr_data = 6'b01_0000; //TA+写数据
localparam st_rd_data = 6'b10_0000; //TA+读数据
//reg define
reg [5:0] cur_state ;
reg [5:0] next_state;
reg [5:0] clk_cnt ; //分频计数
reg [15:0] wr_data_t ; //缓存写寄存器的数据
reg [4:0] addr_t ; //缓存寄存器地址
reg [6:0] cnt ; //计数器
reg st_done ; //状态开始跳转信号
reg [1:0] op_code ; //操作码 2'b01(写) 2'b10(读)
reg mdio_dir ; //MDIO数据(SDA)方向控制
reg mdio_out ; //MDIO输出信号
reg [15:0] rd_data_t ; //缓存读寄存器数据
//wire define
wire mdio_in ; //MDIO数据输入
wire [5:0] clk_divide ; //PHY_CLK的分频系数
assign eth_mdio = mdio_dir ? mdio_out : 1'bz; //控制双向io方向
assign mdio_in = eth_mdio; //MDIO数据输入
//将PHY_CLK的分频系数除以2,得到dri_clk的分频系数,方便对MDC和MDIO信号操作
assign clk_divide = CLK_DIV >> 1;
//分频得到dri_clk时钟
always @(posedge clk or negedge rst_n) begin
if(!rst_n) begin
dri_clk <= 1'b0;
clk_cnt <= 1'b0;
end
else if(clk_cnt == clk_divide[5:1] - 1'd1) begin
clk_cnt <= 1'b0;
dri_clk <= ~dri_clk;
end
else
clk_cnt <= clk_cnt + 1'b1;
end
//产生PHY_MDC时钟
always @(posedge dri_clk or negedge rst_n) begin
if(!rst_n)
eth_mdc <= 1'b1;
else if(cnt[0] == 1'b0)
eth_mdc <= 1'b1;
else
eth_mdc <= 1'b0;
end
//(三段式状态机)同步时序描述状态转移
always @(posedge dri_clk or negedge rst_n) begin
if(!rst_n)
cur_state <= st_idle;
else
cur_state <= next_state;
end
//组合逻辑判断状态转移条件
always @(*) begin
next_state = st_idle;
case(cur_state)
st_idle : begin
if(op_exec)
next_state = st_pre;
else
next_state = st_idle;
end
st_pre : begin
if(st_done)
next_state = st_start;
else
next_state = st_pre;
end
st_start : begin
if(st_done)
next_state = st_addr;
else
next_state = st_start;
end
st_addr : begin
if(st_done) begin
if(op_code == 2'b01) //MDIO接口写操作
next_state = st_wr_data;
else
next_state = st_rd_data; //MDIO接口读操作
end
else
next_state = st_addr;
end
st_wr_data : begin
if(st_done)
next_state = st_idle;
else
next_state = st_wr_data;
end
st_rd_data : begin
if(st_done)
next_state = st_idle;
else
next_state = st_rd_data;
end
default : next_state = st_idle;
endcase
end
//时序电路描述状态输出
always @(posedge dri_clk or negedge rst_n) begin
if(!rst_n) begin
cnt <= 5'd0;
op_code <= 1'b0;
addr_t <= 1'b0;
wr_data_t <= 1'b0;
rd_data_t <= 1'b0;
op_done <= 1'b0;
st_done <= 1'b0;
op_rd_data <= 1'b0;
op_rd_ack <= 1'b1;
mdio_dir <= 1'b0;
mdio_out <= 1'b1;
end
else begin
st_done <= 1'b0 ;
cnt <= cnt +1'b1 ;
case(cur_state)
st_idle : begin
mdio_out <= 1'b1;
mdio_dir <= 1'b0;
op_done <= 1'b0;
cnt <= 7'b0;
if(op_exec) begin
op_code <= {op_rh_wl,~op_rh_wl}; //OP_CODE: 2'b01(写) 2'b10(读)
addr_t <= op_addr;
wr_data_t <= op_wr_data;
op_rd_ack <= 1'b1;
end
end
st_pre : begin //发送前导码:32个1bit
mdio_dir <= 1'b1; //切换MDIO引脚方向:输出
mdio_out <= 1'b1; //MDIO引脚输出高电平
if(cnt == 7'd62)
st_done <= 1'b1;
else if(cnt == 7'd63)
cnt <= 7'b0;
end
st_start : begin
case(cnt)
7'd1 : mdio_out <= 1'b0; //发送开始信号 2'b01
7'd3 : mdio_out <= 1'b1;
7'd5 : mdio_out <= op_code[1]; //发送操作码
7'd6 : st_done <= 1'b1;
7'd7 : begin
mdio_out <= op_code[0];
cnt <= 7'b0;
end
default : ;
endcase
end
st_addr : begin
case(cnt)
7'd1 : mdio_out <= PHY_ADDR[4]; //发送PHY地址
7'd3 : mdio_out <= PHY_ADDR[3];
7'd5 : mdio_out <= PHY_ADDR[2];
7'd7 : mdio_out <= PHY_ADDR[1];
7'd9 : mdio_out <= PHY_ADDR[0];
7'd11: mdio_out <= addr_t[4]; //发送寄存器地址
7'd13: mdio_out <= addr_t[3];
7'd15: mdio_out <= addr_t[2];
7'd17: mdio_out <= addr_t[1];
7'd18: st_done <= 1'b1;
7'd19: begin
mdio_out <= addr_t[0];
cnt <= 7'd0;
end
default : ;
endcase
end
st_wr_data : begin
case(cnt)
7'd1 : mdio_out <= 1'b1; //发送TA,写操作(2'b10)
7'd3 : mdio_out <= 1'b0;
7'd5 : mdio_out <= wr_data_t[15];//发送写寄存器数据
7'd7 : mdio_out <= wr_data_t[14];
7'd9 : mdio_out <= wr_data_t[13];
7'd11: mdio_out <= wr_data_t[12];
7'd13: mdio_out <= wr_data_t[11];
7'd15: mdio_out <= wr_data_t[10];
7'd17: mdio_out <= wr_data_t[9];
7'd19: mdio_out <= wr_data_t[8];
7'd21: mdio_out <= wr_data_t[7];
7'd23: mdio_out <= wr_data_t[6];
7'd25: mdio_out <= wr_data_t[5];
7'd27: mdio_out <= wr_data_t[4];
7'd29: mdio_out <= wr_data_t[3];
7'd31: mdio_out <= wr_data_t[2];
7'd33: mdio_out <= wr_data_t[1];
7'd35: mdio_out <= wr_data_t[0];
7'd37: begin
mdio_dir <= 1'b0;
mdio_out <= 1'b1;
end
7'd39: st_done <= 1'b1;
7'd40: begin
cnt <= 7'b0;
op_done <= 1'b1; //写操作完成,拉高op_done信号
end
default : ;
endcase
end
st_rd_data : begin
case(cnt)
7'd1 : begin
mdio_dir <= 1'b0; //MDIO引脚切换至输入状态
mdio_out <= 1'b1;
end
7'd2 : ; //TA[1]位,该位为高阻状态,不操作
7'd4 : op_rd_ack <= mdio_in; //TA[0]位,0(应答) 1(未应答)
7'd6 : rd_data_t[15] <= mdio_in; //接收寄存器数据
7'd8 : rd_data_t[14] <= mdio_in;
7'd10: rd_data_t[13] <= mdio_in;
7'd12: rd_data_t[12] <= mdio_in;
7'd14: rd_data_t[11] <= mdio_in;
7'd16: rd_data_t[10] <= mdio_in;
7'd18: rd_data_t[9] <= mdio_in;
7'd20: rd_data_t[8] <= mdio_in;
7'd22: rd_data_t[7] <= mdio_in;
7'd24: rd_data_t[6] <= mdio_in;
7'd26: rd_data_t[5] <= mdio_in;
7'd28: rd_data_t[4] <= mdio_in;
7'd30: rd_data_t[3] <= mdio_in;
7'd32: rd_data_t[2] <= mdio_in;
7'd34: rd_data_t[1] <= mdio_in;
7'd36: rd_data_t[0] <= mdio_in;
7'd39: st_done <= 1'b1;
7'd40: begin
op_done <= 1'b1; //读操作完成,拉高op_done信号
op_rd_data <= rd_data_t;
rd_data_t <= 16'd0;
cnt <= 7'd0;
end
default : ;
endcase
end
default : ;
endcase
end
end
endmodule
（2）使用MDIO驱动的代码
mdio_ctrl文件：对寄存器进行读写配置，主要还是读取状态，用于显示
1.基本控制寄存器地址：0x00
代码里面配置为16’h9140 即1001_0001_0100_0000
2.基本状态寄存器地址：0x01
用来读出转态信息
3.特定状态寄存器地址：0x11
module mdio_ctrl(
input clk ,
input rst_n ,
input soft_rst_trig , //软复位触发信号
input op_done , //读写完成
input [15:0] op_rd_data , //读出的数据
input op_rd_ack , //读应答信号 0:应答 1:未应答
output reg op_exec , //触发开始信号
output reg op_rh_wl , //低电平写，高电平读
output reg [4:0] op_addr , //寄存器地址
output reg [15:0] op_wr_data , //写入寄存器的数据
output [1:0] led //LED灯指示以太网连接状态
);
//reg define
reg rst_trig_d0;
reg rst_trig_d1;
reg rst_trig_flag; //soft_rst_trig信号触发标志
reg [23:0] timer_cnt; //定时计数器
reg timer_done; //定时完成信号
reg start_next; //开始读下一个寄存器标致
reg read_next; //处于读下一个寄存器的过程
reg link_error; //链路断开或者自协商未完成
reg [2:0] flow_cnt; //流程控制计数器
reg [1:0] speed_status; //连接速率
//wire define
wire pos_rst_trig; //soft_rst_trig信号上升沿
//采soft_rst_trig信号上升沿
assign pos_rst_trig = ~rst_trig_d1 & rst_trig_d0;
//未连接或连接失败时led赋值00
// 01:10Mbps 10:100Mbps 11:1000Mbps 00：其他情况
assign led = link_error ? 2'b00: speed_status;
//对soft_rst_trig信号延时打拍
always @(posedge clk or negedge rst_n) begin
if(!rst_n) begin
rst_trig_d0 <= 1'b0;
rst_trig_d1 <= 1'b0;
end
else begin
rst_trig_d0 <= soft_rst_trig;
rst_trig_d1 <= rst_trig_d0;
end
end
//定时计数
always @(posedge clk or negedge rst_n) begin
if(!rst_n) begin
timer_cnt <= 1'b0;
timer_done <= 1'b0;
end
else begin
if(timer_cnt == 24'd1_000_000 - 1'b1) begin
timer_done <= 1'b1;
timer_cnt <= 1'b0;
end
else begin
timer_done <= 1'b0;
timer_cnt <= timer_cnt + 1'b1;
end
end
end
//根据软复位信号对MDIO接口进行软复位,并定时读取以太网的连接状态
always @(posedge clk or negedge rst_n) begin
if(!rst_n) begin
flow_cnt <= 3'd0;
rst_trig_flag <= 1'b0;
speed_status <= 2'b00;
op_exec <= 1'b0;
op_rh_wl <= 1'b0;
op_addr <= 1'b0;
op_wr_data <= 1'b0;
start_next <= 1'b0;
read_next <= 1'b0;
link_error <= 1'b0;
end
else begin
op_exec <= 1'b0;
if(pos_rst_trig)
rst_trig_flag <= 1'b1; //拉高软复位触发标志
case(flow_cnt)
2'd0 : begin
if(rst_trig_flag) begin //开始对MDIO接口进行软复位
op_exec <= 1'b1;
op_rh_wl <= 1'b0;
op_addr <= 5'h00;
op_wr_data <= 16'h9140; // Bit[15]=1'b1,表示软复位
flow_cnt <= 3'd1;
end
else if(timer_done) begin //定时完成,获取以太网连接状态
op_exec <= 1'b1;
op_rh_wl <= 1'b1;
op_addr <= 5'h01;
flow_cnt <= 3'd2;
end
else if(start_next) begin //开始读下一个寄存器，获取以太网通信速度
op_exec <= 1'b1;
op_rh_wl <= 1'b1;
op_addr <= 5'h11;
flow_cnt <= 3'd2;
start_next <= 1'b0;
read_next <= 1'b1;
end
end
2'd1 : begin
if(op_done) begin //MDIO接口软复位完成
flow_cnt <= 3'd0;
rst_trig_flag <= 1'b0;
end
end
2'd2 : begin
if(op_done) begin //MDIO接口读操作完成
if(op_rd_ack == 1'b0 && read_next == 1'b0) //读第一个寄存器，接口成功应答，
flow_cnt <= 3'd3; //读第下一个寄存器，接口成功应答
else if(op_rd_ack == 1'b0 && read_next == 1'b1)begin
read_next <= 1'b0;
flow_cnt <= 3'd4;
end
else begin
flow_cnt <= 3'd0;
end
end
end
2'd3 : begin
flow_cnt <= 3'd0; //链路正常并且自协商完成
if(op_rd_data[5] == 1'b1 && op_rd_data[2] == 1'b1)begin
start_next <= 1;
link_error <= 0;
end
else begin
link_error <= 1'b1;
end
end
3'd4: begin
flow_cnt <= 3'd0;
if(op_rd_data[15:14] == 2'b10)
speed_status <= 2'b11; //1000Mbps
else if(op_rd_data[15:14] == 2'b01)
speed_status <= 2'b10; //100Mbps
else if(op_rd_data[15:14] == 2'b00)
speed_status <= 2'b01; //10Mbps
else
speed_status <= 2'b00; //其他情况
end
endcase
end
end
endmodule
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