8 自定义IP核

前面学过AXI GPIO,这个实验使用的是赛灵斯官方的IP核去实现的功能。赛灵斯官方提供了很多的IP核,比如AXI DMI、AXI VDMI等等,但这些IP核往往是针对通用的使用场景,并不能事完全适应各种情况,那这时候就需要程序员去自己编写Verilog代码,封装成自己的IP核加入到Block Design里面,这个就叫自定义的IP核。

ZYNQ包含PS和PL,PS跟PL是怎么通信的呢——通过AXI接口通信对吧,所以说自己在实现功能的时候,难免是需要写AXI的接口协议,而这个Vivado软件提供了一种封装IP核的形式,它可以封装带AXI接口的一个IP核,简单说程序员只专注实现核心功能,利用AXI进行PS和PL通信部分软件能自动生成。

8.1 自定义IP核概述

自定义IP核是指在Vivado软件环境下,借助创建和封装IP向导的功能,把用户按照特定需求所设计的硬件模块封装成IP核的形式。

上图是正点原子创建的IP核,首先创建了一个带AXI接口的IP核,然后进行修改,最终实现PWM功能。

自定义IP核的官方参考文档:UG1118: User Guide: Creating and Packaging Custom IP

下面看一下Block Design支持的输入类型:

8.2 实验任务

本章的实验任务是通过自定义一个LED IP核,来控制PL LED呈现呼吸灯的效果,并且PS可以通过AXI接口控制呼吸灯的开关和呼吸的频率。

其实这个实现思路也比较简单,通过Vivado软件创建一个带AXI接口的IP核,因为本实验中PS与PL交互的数据很少,所以可以创建一个AXI4-Light接口的IP核。创建好之后,在这个代码的基础上添加呼吸灯的功能,像前面的FPGA设计里面也讲解了呼吸灯的实现,所以说可以把它们融合到一起,就可以实现实验任务了。然后PS制呼吸灯的开关和频率,所以PS代码就通过Vitis软件编写C代码实现。这就是设计思路。

8.3 实验系统框图

8.4 硬件设计

首先,打开Vivado软件,之前打开软件之后都是创建一个新的工程,而本次是去管理IP核,所以本次点击选项manager ip:

1784814826929

点击完成后,进入初始界面,选择“创建和打包一个新的IP”:

下面会弹出设置页面:

完成后,选择编辑IP核:

此时,会打开一个新的Vivado工程,在这个工程里面就可以对这个IP核进行修改。

  • breath_led_ip_v1_0文件
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`timescale 1 ns / 1 ps

module breath_led_ip_v1_0 #
(
// Users to add parameters here
parameter START_FREQ_STEP = 10'd1,//设置频率步长初始值
// User parameters ends
// Do not modify the parameters beyond this line


// Parameters of Axi Slave Bus Interface S0_AXI
parameter integer C_S0_AXI_DATA_WIDTH = 32,
parameter integer C_S0_AXI_ADDR_WIDTH = 4
)
(
// Users to add ports here
output led,
// User ports ends
// Do not modify the ports beyond this line


// Ports of Axi Slave Bus Interface S0_AXI
input wire s0_axi_aclk,
input wire s0_axi_aresetn,
input wire [C_S0_AXI_ADDR_WIDTH-1 : 0] s0_axi_awaddr,
input wire [2 : 0] s0_axi_awprot,
input wire s0_axi_awvalid,
output wire s0_axi_awready,
input wire [C_S0_AXI_DATA_WIDTH-1 : 0] s0_axi_wdata,
input wire [(C_S0_AXI_DATA_WIDTH/8)-1 : 0] s0_axi_wstrb,
input wire s0_axi_wvalid,
output wire s0_axi_wready,
output wire [1 : 0] s0_axi_bresp,
output wire s0_axi_bvalid,
input wire s0_axi_bready,
input wire [C_S0_AXI_ADDR_WIDTH-1 : 0] s0_axi_araddr,
input wire [2 : 0] s0_axi_arprot,
input wire s0_axi_arvalid,
output wire s0_axi_arready,
output wire [C_S0_AXI_DATA_WIDTH-1 : 0] s0_axi_rdata,
output wire [1 : 0] s0_axi_rresp,
output wire s0_axi_rvalid,
input wire s0_axi_rready
);
// Instantiation of Axi Bus Interface S0_AXI
breath_led_ip_v1_0_S0_AXI # (
.START_FREQ_STEP(START_FREQ_STEP),
.C_S_AXI_DATA_WIDTH(C_S0_AXI_DATA_WIDTH),
.C_S_AXI_ADDR_WIDTH(C_S0_AXI_ADDR_WIDTH)
) breath_led_ip_v1_0_S0_AXI_inst (
.led(led),
.S_AXI_ACLK(s0_axi_aclk),
.S_AXI_ARESETN(s0_axi_aresetn),
.S_AXI_AWADDR(s0_axi_awaddr),
.S_AXI_AWPROT(s0_axi_awprot),
.S_AXI_AWVALID(s0_axi_awvalid),
.S_AXI_AWREADY(s0_axi_awready),
.S_AXI_WDATA(s0_axi_wdata),
.S_AXI_WSTRB(s0_axi_wstrb),
.S_AXI_WVALID(s0_axi_wvalid),
.S_AXI_WREADY(s0_axi_wready),
.S_AXI_BRESP(s0_axi_bresp),
.S_AXI_BVALID(s0_axi_bvalid),
.S_AXI_BREADY(s0_axi_bready),
.S_AXI_ARADDR(s0_axi_araddr),
.S_AXI_ARPROT(s0_axi_arprot),
.S_AXI_ARVALID(s0_axi_arvalid),
.S_AXI_ARREADY(s0_axi_arready),
.S_AXI_RDATA(s0_axi_rdata),
.S_AXI_RRESP(s0_axi_rresp),
.S_AXI_RVALID(s0_axi_rvalid),
.S_AXI_RREADY(s0_axi_rready)
);

// Add user logic here

// User logic ends

endmodule
  • breath_led_ip_v1_0_S0_AXI.v文件
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`timescale 1 ns / 1 ps

module breath_led_ip_v1_0_S0_AXI #
(
// Users to add parameters here
parameter START_FREQ_STEP = 10'd1, //设置频率步长初始值
// User parameters ends
// Do not modify the parameters beyond this line

// Width of S_AXI data bus
parameter integer C_S_AXI_DATA_WIDTH = 32,
// Width of S_AXI address bus
parameter integer C_S_AXI_ADDR_WIDTH = 4
)
(
// Users to add ports here
output led ,//LED
// User ports ends
// Do not modify the ports beyond this line

// Global Clock Signal
input wire S_AXI_ACLK,
// Global Reset Signal. This Signal is Active LOW
input wire S_AXI_ARESETN,
// Write address (issued by master, acceped by Slave)
input wire [C_S_AXI_ADDR_WIDTH-1 : 0] S_AXI_AWADDR,
// Write channel Protection type. This signal indicates the
// privilege and security level of the transaction, and whether
// the transaction is a data access or an instruction access.
input wire [2 : 0] S_AXI_AWPROT,
// Write address valid. This signal indicates that the master signaling
// valid write address and control information.
input wire S_AXI_AWVALID,
// Write address ready. This signal indicates that the slave is ready
// to accept an address and associated control signals.
output wire S_AXI_AWREADY,
// Write data (issued by master, acceped by Slave)
input wire [C_S_AXI_DATA_WIDTH-1 : 0] S_AXI_WDATA,
// Write strobes. This signal indicates which byte lanes hold
// valid data. There is one write strobe bit for each eight
// bits of the write data bus.
input wire [(C_S_AXI_DATA_WIDTH/8)-1 : 0] S_AXI_WSTRB,
// Write valid. This signal indicates that valid write
// data and strobes are available.
input wire S_AXI_WVALID,
// Write ready. This signal indicates that the slave
// can accept the write data.
output wire S_AXI_WREADY,
// Write response. This signal indicates the status
// of the write transaction.
output wire [1 : 0] S_AXI_BRESP,
// Write response valid. This signal indicates that the channel
// is signaling a valid write response.
output wire S_AXI_BVALID,
// Response ready. This signal indicates that the master
// can accept a write response.
input wire S_AXI_BREADY,
// Read address (issued by master, acceped by Slave)
input wire [C_S_AXI_ADDR_WIDTH-1 : 0] S_AXI_ARADDR,
// Protection type. This signal indicates the privilege
// and security level of the transaction, and whether the
// transaction is a data access or an instruction access.
input wire [2 : 0] S_AXI_ARPROT,
// Read address valid. This signal indicates that the channel
// is signaling valid read address and control information.
input wire S_AXI_ARVALID,
// Read address ready. This signal indicates that the slave is
// ready to accept an address and associated control signals.
output wire S_AXI_ARREADY,
// Read data (issued by slave)
output wire [C_S_AXI_DATA_WIDTH-1 : 0] S_AXI_RDATA,
// Read response. This signal indicates the status of the
// read transfer.
output wire [1 : 0] S_AXI_RRESP,
// Read valid. This signal indicates that the channel is
// signaling the required read data.
output wire S_AXI_RVALID,
// Read ready. This signal indicates that the master can
// accept the read data and response information.
input wire S_AXI_RREADY
);

// AXI4LITE signals
reg [C_S_AXI_ADDR_WIDTH-1 : 0] axi_awaddr;
reg axi_awready;
reg axi_wready;
reg [1 : 0] axi_bresp;
reg axi_bvalid;
reg [C_S_AXI_ADDR_WIDTH-1 : 0] axi_araddr;
reg axi_arready;
reg [C_S_AXI_DATA_WIDTH-1 : 0] axi_rdata;
reg [1 : 0] axi_rresp;
reg axi_rvalid;

// Example-specific design signals
// local parameter for addressing 32 bit / 64 bit C_S_AXI_DATA_WIDTH
// ADDR_LSB is used for addressing 32/64 bit registers/memories
// ADDR_LSB = 2 for 32 bits (n downto 2)
// ADDR_LSB = 3 for 64 bits (n downto 3)
localparam integer ADDR_LSB = (C_S_AXI_DATA_WIDTH/32) + 1;
localparam integer OPT_MEM_ADDR_BITS = 1;
//----------------------------------------------
//-- Signals for user logic register space example
//------------------------------------------------
//-- Number of Slave Registers 4
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg0;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg1;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg2;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg3;
wire slv_reg_rden;
wire slv_reg_wren;
reg [C_S_AXI_DATA_WIDTH-1:0] reg_data_out;
integer byte_index;
reg aw_en;

// I/O Connections assignments

assign S_AXI_AWREADY = axi_awready;
assign S_AXI_WREADY = axi_wready;
assign S_AXI_BRESP = axi_bresp;
assign S_AXI_BVALID = axi_bvalid;
assign S_AXI_ARREADY = axi_arready;
assign S_AXI_RDATA = axi_rdata;
assign S_AXI_RRESP = axi_rresp;
assign S_AXI_RVALID = axi_rvalid;
// Implement axi_awready generation
// axi_awready is asserted for one S_AXI_ACLK clock cycle when both
// S_AXI_AWVALID and S_AXI_WVALID are asserted. axi_awready is
// de-asserted when reset is low.

always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
axi_awready <= 1'b0;
aw_en <= 1'b1;
end
else
begin
if (~axi_awready && S_AXI_AWVALID && S_AXI_WVALID && aw_en)
begin
// slave is ready to accept write address when
// there is a valid write address and write data
// on the write address and data bus. This design
// expects no outstanding transactions.
axi_awready <= 1'b1;
aw_en <= 1'b0;
end
else if (S_AXI_BREADY && axi_bvalid)
begin
aw_en <= 1'b1;
axi_awready <= 1'b0;
end
else
begin
axi_awready <= 1'b0;
end
end
end

// Implement axi_awaddr latching
// This process is used to latch the address when both
// S_AXI_AWVALID and S_AXI_WVALID are valid.

always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
axi_awaddr <= 0;
end
else
begin
if (~axi_awready && S_AXI_AWVALID && S_AXI_WVALID && aw_en)
begin
// Write Address latching
axi_awaddr <= S_AXI_AWADDR;
end
end
end

// Implement axi_wready generation
// axi_wready is asserted for one S_AXI_ACLK clock cycle when both
// S_AXI_AWVALID and S_AXI_WVALID are asserted. axi_wready is
// de-asserted when reset is low.

always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
axi_wready <= 1'b0;
end
else
begin
if (~axi_wready && S_AXI_WVALID && S_AXI_AWVALID && aw_en )
begin
// slave is ready to accept write data when
// there is a valid write address and write data
// on the write address and data bus. This design
// expects no outstanding transactions.
axi_wready <= 1'b1;
end
else
begin
axi_wready <= 1'b0;
end
end
end

// Implement memory mapped register select and write logic generation
// The write data is accepted and written to memory mapped registers when
// axi_awready, S_AXI_WVALID, axi_wready and S_AXI_WVALID are asserted. Write strobes are used to
// select byte enables of slave registers while writing.
// These registers are cleared when reset (active low) is applied.
// Slave register write enable is asserted when valid address and data are available
// and the slave is ready to accept the write address and write data.
assign slv_reg_wren = axi_wready && S_AXI_WVALID && axi_awready && S_AXI_AWVALID;

always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
slv_reg0 <= 0;
slv_reg1 <= 0;
slv_reg2 <= 0;
slv_reg3 <= 0;
end
else begin
if (slv_reg_wren)
begin
case ( axi_awaddr[ADDR_LSB+OPT_MEM_ADDR_BITS:ADDR_LSB] )
2'h0:
for ( byte_index = 0; byte_index <= (C_S_AXI_DATA_WIDTH/8)-1; byte_index = byte_index+1 )
if ( S_AXI_WSTRB[byte_index] == 1 ) begin
// Respective byte enables are asserted as per write strobes
// Slave register 0
slv_reg0[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
2'h1:
for ( byte_index = 0; byte_index <= (C_S_AXI_DATA_WIDTH/8)-1; byte_index = byte_index+1 )
if ( S_AXI_WSTRB[byte_index] == 1 ) begin
// Respective byte enables are asserted as per write strobes
// Slave register 1
slv_reg1[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
2'h2:
for ( byte_index = 0; byte_index <= (C_S_AXI_DATA_WIDTH/8)-1; byte_index = byte_index+1 )
if ( S_AXI_WSTRB[byte_index] == 1 ) begin
// Respective byte enables are asserted as per write strobes
// Slave register 2
slv_reg2[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
2'h3:
for ( byte_index = 0; byte_index <= (C_S_AXI_DATA_WIDTH/8)-1; byte_index = byte_index+1 )
if ( S_AXI_WSTRB[byte_index] == 1 ) begin
// Respective byte enables are asserted as per write strobes
// Slave register 3
slv_reg3[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
default : begin
slv_reg0 <= slv_reg0;
slv_reg1 <= slv_reg1;
slv_reg2 <= slv_reg2;
slv_reg3 <= slv_reg3;
end
endcase
end
end
end

// Implement write response logic generation
// The write response and response valid signals are asserted by the slave
// when axi_wready, S_AXI_WVALID, axi_wready and S_AXI_WVALID are asserted.
// This marks the acceptance of address and indicates the status of
// write transaction.

always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
axi_bvalid <= 0;
axi_bresp <= 2'b0;
end
else
begin
if (axi_awready && S_AXI_AWVALID && ~axi_bvalid && axi_wready && S_AXI_WVALID)
begin
// indicates a valid write response is available
axi_bvalid <= 1'b1;
axi_bresp <= 2'b0; // 'OKAY' response
end // work error responses in future
else
begin
if (S_AXI_BREADY && axi_bvalid)
//check if bready is asserted while bvalid is high)
//(there is a possibility that bready is always asserted high)
begin
axi_bvalid <= 1'b0;
end
end
end
end

// Implement axi_arready generation
// axi_arready is asserted for one S_AXI_ACLK clock cycle when
// S_AXI_ARVALID is asserted. axi_awready is
// de-asserted when reset (active low) is asserted.
// The read address is also latched when S_AXI_ARVALID is
// asserted. axi_araddr is reset to zero on reset assertion.

always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
axi_arready <= 1'b0;
axi_araddr <= 32'b0;
end
else
begin
if (~axi_arready && S_AXI_ARVALID)
begin
// indicates that the slave has acceped the valid read address
axi_arready <= 1'b1;
// Read address latching
axi_araddr <= S_AXI_ARADDR;
end
else
begin
axi_arready <= 1'b0;
end
end
end

// Implement axi_arvalid generation
// axi_rvalid is asserted for one S_AXI_ACLK clock cycle when both
// S_AXI_ARVALID and axi_arready are asserted. The slave registers
// data are available on the axi_rdata bus at this instance. The
// assertion of axi_rvalid marks the validity of read data on the
// bus and axi_rresp indicates the status of read transaction.axi_rvalid
// is deasserted on reset (active low). axi_rresp and axi_rdata are
// cleared to zero on reset (active low).
always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
axi_rvalid <= 0;
axi_rresp <= 0;
end
else
begin
if (axi_arready && S_AXI_ARVALID && ~axi_rvalid)
begin
// Valid read data is available at the read data bus
axi_rvalid <= 1'b1;
axi_rresp <= 2'b0; // 'OKAY' response
end
else if (axi_rvalid && S_AXI_RREADY)
begin
// Read data is accepted by the master
axi_rvalid <= 1'b0;
end
end
end

// Implement memory mapped register select and read logic generation
// Slave register read enable is asserted when valid address is available
// and the slave is ready to accept the read address.
assign slv_reg_rden = axi_arready & S_AXI_ARVALID & ~axi_rvalid;
always @(*)
begin
// Address decoding for reading registers
case ( axi_araddr[ADDR_LSB+OPT_MEM_ADDR_BITS:ADDR_LSB] )
2'h0 : reg_data_out <= slv_reg0;
2'h1 : reg_data_out <= slv_reg1;
2'h2 : reg_data_out <= slv_reg2;
2'h3 : reg_data_out <= slv_reg3;
default : reg_data_out <= 0;
endcase
end

// Output register or memory read data
always @( posedge S_AXI_ACLK )
begin
if ( S_AXI_ARESETN == 1'b0 )
begin
axi_rdata <= 0;
end
else
begin
// When there is a valid read address (S_AXI_ARVALID) with
// acceptance of read address by the slave (axi_arready),
// output the read dada
if (slv_reg_rden)
begin
axi_rdata <= reg_data_out; // register read data
end
end
end

// Add user logic here
breath_led #(
.START_FREQ_STEP (START_FREQ_STEP)
)
u_breath_led(
.sys_clk (S_AXI_ACLK),
.sys_rst_n (S_AXI_ARESETN),
.sw_ctrl (slv_reg0[0]),
.set_en (slv_reg1[31]),
.set_freq_step (slv_reg1[9:0]),
.led (led)
);
// User logic ends

endmodule
  • breath_led.v自己编写的呼吸灯文件
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module breath_led(
input sys_clk , //系统时钟 50MHz
input sys_rst_n , //系统复位,低电平有效
input sw_ctrl , //呼吸灯开关控制信号 1:亮 0:灭
input set_en , //设置呼吸灯频率设置使能信号
input [9:0] set_freq_step , //设置呼吸灯频率变化步长

output led //LED灯
);

//parameter define
parameter START_FREQ_STEP = 10'd1; //设置频率步长初始值
parameter CNT_2US_MAX = 7'd100;
parameter CNT_2MS_MAX = 10'd1000;
parameter CNT_2S_MAX = 10'd1000;

//reg define
reg [6:0] cnt_2us;
reg [9:0] cnt_2ms;
reg [9:0] cnt_2s;
reg inc_dec_flag; //亮度递增/递减 0:递增 1:递减
reg [9:0] freq_step ; //呼吸灯频率间隔步长
reg led_t ;

//*****************************************************
//** main code
//*****************************************************
assign led = led_t & sw_ctrl;

//设置频率间隔,频率步长值在1-10之间
always @(posedge sys_clk) begin
if(!sys_rst_n)
freq_step <= START_FREQ_STEP;
else if(set_en) begin
if(set_freq_step == 0)
freq_step <= 10'd1;
else if(set_freq_step >= 10'd10)
freq_step <= 10'd10;
else
freq_step <= set_freq_step;
end
end

//cnt_2us:计数2us
always@(posedge sys_clk or negedge sys_rst_n) begin
if(!sys_rst_n)
cnt_2us <= 7'b0;
else if(cnt_2us == (CNT_2US_MAX - 7'b1 ))
cnt_2us <= 7'b0;
else
cnt_2us <= cnt_2us + 7'b1;
end

//cnt_2ms:计数2ms
always@(posedge sys_clk or negedge sys_rst_n) begin
if(!sys_rst_n)
cnt_2ms <= 10'b0;
else if(cnt_2ms == (CNT_2MS_MAX - 10'b1) && cnt_2us == (CNT_2US_MAX - 7'b1))
cnt_2ms <= 10'b0;
else if(cnt_2us == CNT_2US_MAX - 7'b1)
cnt_2ms <= cnt_2ms + 10'b1;
else
cnt_2ms <= cnt_2ms;
end

//cnt_2s:计数2s
always@(posedge sys_clk or negedge sys_rst_n) begin
if(!sys_rst_n)
cnt_2s <= 10'b0;
else if(cnt_2s >= (CNT_2S_MAX - 10'b1) && cnt_2ms == (CNT_2MS_MAX - 10'b1) && cnt_2us == (CNT_2US_MAX - 7'b1))
cnt_2s <= 10'b0;
else if(cnt_2ms == (CNT_2MS_MAX - 10'b1) && cnt_2us == (CNT_2US_MAX - 7'b1))
cnt_2s <= cnt_2s + freq_step;
else
cnt_2s <= cnt_2s;
end

//inc_dec_flag为低电平,led灯由暗变亮,inc_dec_flag为高电平,led灯由亮变暗
always@(posedge sys_clk or negedge sys_rst_n) begin
if(!sys_rst_n)
inc_dec_flag <= 1'b0;
else if(cnt_2s >= (CNT_2S_MAX - 10'b1) && cnt_2ms ==( CNT_2MS_MAX - 10'b1) && cnt_2us == (CNT_2US_MAX - 7'b1))
inc_dec_flag <= ~inc_dec_flag;
else
inc_dec_flag <= inc_dec_flag;
end

//led:输出信号连接到外部的led灯
always@(posedge sys_clk or negedge sys_rst_n) begin
if(!sys_rst_n)
led_t <= 1'b0;
else if((inc_dec_flag == 1'b1 && cnt_2ms >= cnt_2s) || (inc_dec_flag == 1'b0 && cnt_2ms <= cnt_2s))
led_t <= 1'b1;
else
led_t<= 1'b0;
end

endmodule