使用verilog写一个iic通信模块
时间: 2023-12-04 21:00:36 浏览: 21
以下是一个简单的I2C通信模块的Verilog代码示例:
```
module i2c_master(
input clk,
input rst_n,
input sda_i,
output sda_o,
inout scl_io
);
parameter SCL_HIGH_TIME = 10; // SCL线高电平时间
parameter SCL_LOW_TIME = 10; // SCL线低电平时间
parameter SDA_HOLD_TIME = 5; // SDA线保持时间
// I2C状态机
typedef enum logic [2:0] {
IDLE,
START,
ADDR,
DATA,
STOP
} i2c_state_t;
i2c_state_t state, next_state;
logic [7:0] addr, data;
logic [2:0] bit_cnt;
logic [2:0] scl_cnt;
logic [2:0] sda_hold_cnt;
// 初始化状态
initial begin
state = IDLE;
end
// 每个时钟周期执行
always @(posedge clk or negedge rst_n) begin
if (!rst_n) begin // 复位
state <= IDLE;
scl_io <= 1'b1;
sda_o <= 1'b1;
bit_cnt <= 3'b0;
scl_cnt <= 3'b0;
sda_hold_cnt <= 3'b0;
end else begin
case (state)
IDLE: begin // 空闲状态
if (!sda_i && !scl_io) begin // 接收到起始位
next_state = START;
bit_cnt <= 3'b0;
end else begin
next_state = IDLE;
end
end
START: begin // 起始位
if (scl_cnt < SCL_HIGH_TIME) begin
scl_io <= 1'b1;
scl_cnt <= scl_cnt + 1;
end else if (bit_cnt < 8) begin
sda_o <= 1'b0;
bit_cnt <= bit_cnt + 1;
end else begin
next_state = ADDR;
bit_cnt <= 3'b0;
end
end
ADDR: begin // 地址位
if (scl_cnt < SCL_HIGH_TIME) begin
scl_io <= 1'b1;
scl_cnt <= scl_cnt + 1;
end else if (bit_cnt < 8) begin
sda_o <= addr[7-bit_cnt];
bit_cnt <= bit_cnt + 1;
end else if (!sda_i) begin // 接收到ACK
next_state = DATA;
bit_cnt <= 3'b0;
end else begin // 未接收到ACK
next_state = STOP;
bit_cnt <= 3'b0;
end
end
DATA: begin // 数据位
if (scl_cnt < SCL_HIGH_TIME) begin
scl_io <= 1'b1;
scl_cnt <= scl_cnt + 1;
end else if (bit_cnt < 8) begin
sda_o <= data[7-bit_cnt];
bit_cnt <= bit_cnt + 1;
end else if (!sda_i) begin // 接收到ACK
next_state = DATA;
bit_cnt <= 3'b0;
end else begin // 未接收到ACK
next_state = STOP;
bit_cnt <= 3'b0;
end
end
STOP: begin // 停止位
if (scl_cnt < SCL_HIGH_TIME) begin
scl_io <= 1'b1;
scl_cnt <= scl_cnt + 1;
end else if (sda_hold_cnt < SDA_HOLD_TIME) begin
sda_o <= 1'b0;
sda_hold_cnt <= sda_hold_cnt + 1;
end else begin
sda_o <= 1'b1;
state <= IDLE;
scl_io <= 1'b0;
scl_cnt <= 3'b0;
sda_hold_cnt <= 3'b0;
end
end
endcase
state <= next_state;
end
end
endmodule
```
这个模块实现了一个I2C主机,它能够发送起始位、地址位、数据位和停止位,并且可以接收从设备的ACK信号。在使用时,需要将模块中的addr和data信号分别绑定到要发送的地址和数据上,并将sda_i连接到从设备的SDA线上,scl_io连接到I2C总线的SCL线上,sda_o连接到I2C总线的SDA线上。同时,需要提供一个时钟信号clk和一个复位信号rst_n。