AXI lite总线读写时序
1. AXI_SLAVE源码
`timescale 1 ns / 1 ps
module myip_v1_0_S00_AXI #
(
// Users to add parameters here
// 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 = 7
)
(
// Users to add ports here
// 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 = 4;
//----------------------------------------------
//-- Signals for user logic register space example
//------------------------------------------------
//-- Number of Slave Registers 20
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;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg4;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg5;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg6;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg7;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg8;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg9;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg10;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg11;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg12;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg13;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg14;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg15;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg16;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg17;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg18;
reg [C_S_AXI_DATA_WIDTH-1:0] slv_reg19;
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;
slv_reg4 <= 0;
slv_reg5 <= 0;
slv_reg6 <= 0;
slv_reg7 <= 0;
slv_reg8 <= 0;
slv_reg9 <= 0;
slv_reg10 <= 0;
slv_reg11 <= 0;
slv_reg12 <= 0;
slv_reg13 <= 0;
slv_reg14 <= 0;
slv_reg15 <= 0;
slv_reg16 <= 0;
slv_reg17 <= 0;
slv_reg18 <= 0;
slv_reg19 <= 0;
end
else begin
if (slv_reg_wren)
begin
case ( axi_awaddr[ADDR_LSB+OPT_MEM_ADDR_BITS:ADDR_LSB] )
5'h00:
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
5'h01:
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
5'h02:
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
5'h03:
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
5'h04:
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 4
slv_reg4[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h05:
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 5
slv_reg5[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h06:
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 6
slv_reg6[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h07:
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 7
slv_reg7[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h08:
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 8
slv_reg8[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h09:
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 9
slv_reg9[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h0A:
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 10
slv_reg10[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h0B:
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 11
slv_reg11[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h0C:
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 12
slv_reg12[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h0D:
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 13
slv_reg13[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h0E:
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 14
slv_reg14[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h0F:
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 15
slv_reg15[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h10:
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 16
slv_reg16[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h11:
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 17
slv_reg17[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h12:
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 18
slv_reg18[(byte_index*8) +: 8] <= S_AXI_WDATA[(byte_index*8) +: 8];
end
5'h13:
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 19
slv_reg19[(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;
slv_reg4 <= slv_reg4;
slv_reg5 <= slv_reg5;
slv_reg6 <= slv_reg6;
slv_reg7 <= slv_reg7;
slv_reg8 <= slv_reg8;
slv_reg9 <= slv_reg9;
slv_reg10 <= slv_reg10;
slv_reg11 <= slv_reg11;
slv_reg12 <= slv_reg12;
slv_reg13 <= slv_reg13;
slv_reg14 <= slv_reg14;
slv_reg15 <= slv_reg15;
slv_reg16 <= slv_reg16;
slv_reg17 <= slv_reg17;
slv_reg18 <= slv_reg18;
slv_reg19 <= slv_reg19;
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] )
5'h00 : reg_data_out <= slv_reg0;
5'h01 : reg_data_out <= slv_reg1;
5'h02 : reg_data_out <= slv_reg2;
5'h03 : reg_data_out <= slv_reg3;
5'h04 : reg_data_out <= slv_reg4;
5'h05 : reg_data_out <= slv_reg5;
5'h06 : reg_data_out <= slv_reg6;
5'h07 : reg_data_out <= slv_reg7;
5'h08 : reg_data_out <= slv_reg8;
5'h09 : reg_data_out <= slv_reg9;
5'h0A : reg_data_out <= slv_reg10;
5'h0B : reg_data_out <= slv_reg11;
5'h0C : reg_data_out <= slv_reg12;
5'h0D : reg_data_out <= slv_reg13;
5'h0E : reg_data_out <= slv_reg14;
5'h0F : reg_data_out <= slv_reg15;
5'h10 : reg_data_out <= slv_reg16;
5'h11 : reg_data_out <= slv_reg17;
5'h12 : reg_data_out <= slv_reg18;
5'h13 : reg_data_out <= slv_reg19;
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
// User logic ends
endmodule
2. AXI_MASTER源码
`timescale 1 ns / 1 ps
module myip_v1_0_M00_AXI #
(
// Users to add parameters here
// User parameters ends
// Do not modify the parameters beyond this line
// The master will start generating data from the C_M_START_DATA_VALUE value
parameter C_M_START_DATA_VALUE = 32'hAA000000,
// The master requires a target slave base address.
// The master will initiate read and write transactions on the slave with base address specified here as a parameter.
parameter C_M_TARGET_SLAVE_BASE_ADDR = 32'h40000000,
// Width of M_AXI address bus.
// The master generates the read and write addresses of width specified as C_M_AXI_ADDR_WIDTH.
parameter integer C_M_AXI_ADDR_WIDTH = 32,
// Width of M_AXI data bus.
// The master issues write data and accept read data where the width of the data bus is C_M_AXI_DATA_WIDTH
parameter integer C_M_AXI_DATA_WIDTH = 32,
// Transaction number is the number of write
// and read transactions the master will perform as a part of this example memory test.
parameter integer C_M_TRANSACTIONS_NUM = 4
)
(
// Users to add ports here
// User ports ends
// Do not modify the ports beyond this line
// Initiate AXI transactions
input wire INIT_AXI_TXN,
// Asserts when ERROR is detected
output reg ERROR,
// Asserts when AXI transactions is complete
output wire TXN_DONE,
// AXI clock signal
input wire M_AXI_ACLK,
// AXI active low reset signal
input wire M_AXI_ARESETN,
// Master Interface Write Address Channel ports. Write address (issued by master)
output wire [C_M_AXI_ADDR_WIDTH-1 : 0] M_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.
output wire [2 : 0] M_AXI_AWPROT,
// Write address valid.
// This signal indicates that the master signaling valid write address and control information.
output wire M_AXI_AWVALID,
// Write address ready.
// This signal indicates that the slave is ready to accept an address and associated control signals.
input wire M_AXI_AWREADY,
// Master Interface Write Data Channel ports. Write data (issued by master)
output wire [C_M_AXI_DATA_WIDTH-1 : 0] M_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.
output wire [C_M_AXI_DATA_WIDTH/8-1 : 0] M_AXI_WSTRB,
// Write valid. This signal indicates that valid write data and strobes are available.
output wire M_AXI_WVALID,
// Write ready. This signal indicates that the slave can accept the write data.
input wire M_AXI_WREADY,
// Master Interface Write Response Channel ports.
// This signal indicates the status of the write transaction.
input wire [1 : 0] M_AXI_BRESP,
// Write response valid.
// This signal indicates that the channel is signaling a valid write response
input wire M_AXI_BVALID,
// Response ready. This signal indicates that the master can accept a write response.
output wire M_AXI_BREADY,
// Master Interface Read Address Channel ports. Read address (issued by master)
output wire [C_M_AXI_ADDR_WIDTH-1 : 0] M_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.
output wire [2 : 0] M_AXI_ARPROT,
// Read address valid.
// This signal indicates that the channel is signaling valid read address and control information.
output wire M_AXI_ARVALID,
// Read address ready.
// This signal indicates that the slave is ready to accept an address and associated control signals.
input wire M_AXI_ARREADY,
// Master Interface Read Data Channel ports. Read data (issued by slave)
input wire [C_M_AXI_DATA_WIDTH-1 : 0] M_AXI_RDATA,
// Read response. This signal indicates the status of the read transfer.
input wire [1 : 0] M_AXI_RRESP,
// Read valid. This signal indicates that the channel is signaling the required read data.
input wire M_AXI_RVALID,
// Read ready. This signal indicates that the master can accept the read data and response information.
output wire M_AXI_RREADY
);
// function called clogb2 that returns an integer which has the
// value of the ceiling of the log base 2
function integer clogb2 (input integer bit_depth);
begin
for(clogb2=0; bit_depth>0; clogb2=clogb2+1)
bit_depth = bit_depth >> 1;
end
endfunction
// TRANS_NUM_BITS is the width of the index counter for
// number of write or read transaction.
localparam integer TRANS_NUM_BITS = clogb2(C_M_TRANSACTIONS_NUM-1);
// Example State machine to initialize counter, initialize write transactions,
// initialize read transactions and comparison of read data with the
// written data words.
parameter [1:0] IDLE = 2'b00, // This state initiates AXI4Lite transaction
// after the state machine changes state to INIT_WRITE
// when there is 0 to 1 transition on INIT_AXI_TXN
INIT_WRITE = 2'b01, // This state initializes write transaction,
// once writes are done, the state machine
// changes state to INIT_READ
INIT_READ = 2'b10, // This state initializes read transaction
// once reads are done, the state machine
// changes state to INIT_COMPARE
INIT_COMPARE = 2'b11; // This state issues the status of comparison
// of the written data with the read data
reg [1:0] mst_exec_state;
// AXI4LITE signals
//write address valid
reg axi_awvalid;
//write data valid
reg axi_wvalid;
//read address valid
reg axi_arvalid;
//read data acceptance
reg axi_rready;
//write response acceptance
reg axi_bready;
//write address
reg [C_M_AXI_ADDR_WIDTH-1 : 0] axi_awaddr;
//write data
reg [C_M_AXI_DATA_WIDTH-1 : 0] axi_wdata;
//read addresss
reg [C_M_AXI_ADDR_WIDTH-1 : 0] axi_araddr;
//Asserts when there is a write response error
wire write_resp_error;
//Asserts when there is a read response error
wire read_resp_error;
//A pulse to initiate a write transaction
reg start_single_write;
//A pulse to initiate a read transaction
reg start_single_read;
//Asserts when a single beat write transaction is issued and remains asserted till the completion of write trasaction.
reg write_issued;
//Asserts when a single beat read transaction is issued and remains asserted till the completion of read trasaction.
reg read_issued;
//flag that marks the completion of write trasactions. The number of write transaction is user selected by the parameter C_M_TRANSACTIONS_NUM.
reg writes_done;
//flag that marks the completion of read trasactions. The number of read transaction is user selected by the parameter C_M_TRANSACTIONS_NUM
reg reads_done;
//The error register is asserted when any of the write response error, read response error or the data mismatch flags are asserted.
reg error_reg;
//index counter to track the number of write transaction issued
reg [TRANS_NUM_BITS : 0] write_index;
//index counter to track the number of read transaction issued
reg [TRANS_NUM_BITS : 0] read_index;
//Expected read data used to compare with the read data.
reg [C_M_AXI_DATA_WIDTH-1 : 0] expected_rdata;
//Flag marks the completion of comparison of the read data with the expected read data
reg compare_done;
//This flag is asserted when there is a mismatch of the read data with the expected read data.
reg read_mismatch;
//Flag is asserted when the write index reaches the last write transction number
reg last_write;
//Flag is asserted when the read index reaches the last read transction number
reg last_read;
reg init_txn_ff;
reg init_txn_ff2;
reg init_txn_edge;
wire init_txn_pulse;
// I/O Connections assignments
//Adding the offset address to the base addr of the slave
assign M_AXI_AWADDR = C_M_TARGET_SLAVE_BASE_ADDR + axi_awaddr;
//AXI 4 write data
assign M_AXI_WDATA = axi_wdata;
assign M_AXI_AWPROT = 3'b000;
assign M_AXI_AWVALID = axi_awvalid;
//Write Data(W)
assign M_AXI_WVALID = axi_wvalid;
//Set all byte strobes in this example
assign M_AXI_WSTRB = 4'b1111;
//Write Response (B)
assign M_AXI_BREADY = axi_bready;
//Read Address (AR)
assign M_AXI_ARADDR = C_M_TARGET_SLAVE_BASE_ADDR + axi_araddr;
assign M_AXI_ARVALID = axi_arvalid;
assign M_AXI_ARPROT = 3'b001;
//Read and Read Response (R)
assign M_AXI_RREADY = axi_rready;
//Example design I/O
assign TXN_DONE = compare_done;
assign init_txn_pulse = (!init_txn_ff2) && init_txn_ff;
//Generate a pulse to initiate AXI transaction.
always @(posedge M_AXI_ACLK)
begin
// Initiates AXI transaction delay
if (M_AXI_ARESETN == 0 )
begin
init_txn_ff <= 1'b0;
init_txn_ff2 <= 1'b0;
end
else
begin
init_txn_ff <= INIT_AXI_TXN;
init_txn_ff2 <= init_txn_ff;
end
end
//--------------------
//Write Address Channel
//--------------------
// The purpose of the write address channel is to request the address and
// command information for the entire transaction. It is a single beat
// of information.
// Note for this example the axi_awvalid/axi_wvalid are asserted at the same
// time, and then each is deasserted independent from each other.
// This is a lower-performance, but simplier control scheme.
// AXI VALID signals must be held active until accepted by the partner.
// A data transfer is accepted by the slave when a master has
// VALID data and the slave acknoledges it is also READY. While the master
// is allowed to generated multiple, back-to-back requests by not
// deasserting VALID, this design will add rest cycle for
// simplicity.
// Since only one outstanding transaction is issued by the user design,
// there will not be a collision between a new request and an accepted
// request on the same clock cycle.
always @(posedge M_AXI_ACLK)
begin
//Only VALID signals must be deasserted during reset per AXI spec
//Consider inverting then registering active-low reset for higher fmax
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
axi_awvalid <= 1'b0;
end
//Signal a new address/data command is available by user logic
else
begin
if (start_single_write)
begin
axi_awvalid <= 1'b1;
end
//Address accepted by interconnect/slave (issue of M_AXI_AWREADY by slave)
else if (M_AXI_AWREADY && axi_awvalid)
begin
axi_awvalid <= 1'b0;
end
end
end
// start_single_write triggers a new write
// transaction. write_index is a counter to
// keep track with number of write transaction
// issued/initiated
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
write_index <= 0;
end
// Signals a new write address/ write data is
// available by user logic
else if (start_single_write)
begin
write_index <= write_index + 1;
end
end
//--------------------
//Write Data Channel
//--------------------
//The write data channel is for transfering the actual data.
//The data generation is speific to the example design, and
//so only the WVALID/WREADY handshake is shown here
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
axi_wvalid <= 1'b0;
end
//Signal a new address/data command is available by user logic
else if (start_single_write)
begin
axi_wvalid <= 1'b1;
end
//Data accepted by interconnect/slave (issue of M_AXI_WREADY by slave)
else if (M_AXI_WREADY && axi_wvalid)
begin
axi_wvalid <= 1'b0;
end
end
//----------------------------
//Write Response (B) Channel
//----------------------------
//The write response channel provides feedback that the write has committed
//to memory. BREADY will occur after both the data and the write address
//has arrived and been accepted by the slave, and can guarantee that no
//other accesses launched afterwards will be able to be reordered before it.
//The BRESP bit [1] is used indicate any errors from the interconnect or
//slave for the entire write burst. This example will capture the error.
//While not necessary per spec, it is advisable to reset READY signals in
//case of differing reset latencies between master/slave.
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
axi_bready <= 1'b0;
end
// accept/acknowledge bresp with axi_bready by the master
// when M_AXI_BVALID is asserted by slave
else if (M_AXI_BVALID && ~axi_bready)
begin
axi_bready <= 1'b1;
end
// deassert after one clock cycle
else if (axi_bready)
begin
axi_bready <= 1'b0;
end
// retain the previous value
else
axi_bready <= axi_bready;
end
//Flag write errors
assign write_resp_error = (axi_bready & M_AXI_BVALID & M_AXI_BRESP[1]);
//----------------------------
//Read Address Channel
//----------------------------
//start_single_read triggers a new read transaction. read_index is a counter to
//keep track with number of read transaction issued/initiated
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
read_index <= 0;
end
// Signals a new read address is
// available by user logic
else if (start_single_read)
begin
read_index <= read_index + 1;
end
end
// A new axi_arvalid is asserted when there is a valid read address
// available by the master. start_single_read triggers a new read
// transaction
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
axi_arvalid <= 1'b0;
end
//Signal a new read address command is available by user logic
else if (start_single_read)
begin
axi_arvalid <= 1'b1;
end
//RAddress accepted by interconnect/slave (issue of M_AXI_ARREADY by slave)
else if (M_AXI_ARREADY && axi_arvalid)
begin
axi_arvalid <= 1'b0;
end
// retain the previous value
end
//--------------------------------
//Read Data (and Response) Channel
//--------------------------------
//The Read Data channel returns the results of the read request
//The master will accept the read data by asserting axi_rready
//when there is a valid read data available.
//While not necessary per spec, it is advisable to reset READY signals in
//case of differing reset latencies between master/slave.
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
axi_rready <= 1'b0;
end
// accept/acknowledge rdata/rresp with axi_rready by the master
// when M_AXI_RVALID is asserted by slave
else if (M_AXI_RVALID && ~axi_rready)
begin
axi_rready <= 1'b1;
end
// deassert after one clock cycle
else if (axi_rready)
begin
axi_rready <= 1'b0;
end
// retain the previous value
end
//Flag write errors
assign read_resp_error = (axi_rready & M_AXI_RVALID & M_AXI_RRESP[1]);
//--------------------------------
//User Logic
//--------------------------------
//Address/Data Stimulus
//Address/data pairs for this example. The read and write values should
//match.
//Modify these as desired for different address patterns.
//Write Addresses
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
axi_awaddr <= 0;
end
// Signals a new write address/ write data is
// available by user logic
else if (M_AXI_AWREADY && axi_awvalid)
begin
axi_awaddr <= axi_awaddr + 32'h00000004;
end
end
// Write data generation
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1 )
begin
axi_wdata <= C_M_START_DATA_VALUE;
end
// Signals a new write address/ write data is
// available by user logic
else if (M_AXI_WREADY && axi_wvalid)
begin
axi_wdata <= C_M_START_DATA_VALUE + write_index;
end
end
//Read Addresses
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
axi_araddr <= 0;
end
// Signals a new write address/ write data is
// available by user logic
else if (M_AXI_ARREADY && axi_arvalid)
begin
axi_araddr <= axi_araddr + 32'h00000004;
end
end
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
begin
expected_rdata <= C_M_START_DATA_VALUE;
end
// Signals a new write address/ write data is
// available by user logic
else if (M_AXI_RVALID && axi_rready)
begin
expected_rdata <= C_M_START_DATA_VALUE + read_index;
end
end
//implement master command interface state machine
always @ ( posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 1'b0)
begin
// reset condition
// All the signals are assigned default values under reset condition
mst_exec_state <= IDLE;
start_single_write <= 1'b0;
write_issued <= 1'b0;
start_single_read <= 1'b0;
read_issued <= 1'b0;
compare_done <= 1'b0;
ERROR <= 1'b0;
end
else
begin
// state transition
case (mst_exec_state)
IDLE:
// This state is responsible to initiate
// AXI transaction when init_txn_pulse is asserted
if ( init_txn_pulse == 1'b1 )
begin
mst_exec_state <= INIT_WRITE;
ERROR <= 1'b0;
compare_done <= 1'b0;
end
else
begin
mst_exec_state <= IDLE;
end
INIT_WRITE:
// This state is responsible to issue start_single_write pulse to
// initiate a write transaction. Write transactions will be
// issued until last_write signal is asserted.
// write controller
if (writes_done)
begin
mst_exec_state <= INIT_READ;//
end
else
begin
mst_exec_state <= INIT_WRITE;
if (~axi_awvalid && ~axi_wvalid && ~M_AXI_BVALID && ~last_write && ~start_single_write && ~write_issued)
begin
start_single_write <= 1'b1;
write_issued <= 1'b1;
end
else if (axi_bready)
begin
write_issued <= 1'b0;
end
else
begin
start_single_write <= 1'b0; //Negate to generate a pulse
end
end
INIT_READ:
// This state is responsible to issue start_single_read pulse to
// initiate a read transaction. Read transactions will be
// issued until last_read signal is asserted.
// read controller
if (reads_done)
begin
mst_exec_state <= INIT_COMPARE;
end
else
begin
mst_exec_state <= INIT_READ;
if (~axi_arvalid && ~M_AXI_RVALID && ~last_read && ~start_single_read && ~read_issued)
begin
start_single_read <= 1'b1;
read_issued <= 1'b1;
end
else if (axi_rready)
begin
read_issued <= 1'b0;
end
else
begin
start_single_read <= 1'b0; //Negate to generate a pulse
end
end
INIT_COMPARE:
begin
// This state is responsible to issue the state of comparison
// of written data with the read data. If no error flags are set,
// compare_done signal will be asseted to indicate success.
ERROR <= error_reg;
mst_exec_state <= IDLE;
compare_done <= 1'b1;
end
default :
begin
mst_exec_state <= IDLE;
end
endcase
end
end //MASTER_EXECUTION_PROC
//Terminal write count
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
last_write <= 1'b0;
//The last write should be associated with a write address ready response
else if ((write_index == C_M_TRANSACTIONS_NUM) && M_AXI_AWREADY)
last_write <= 1'b1;
else
last_write <= last_write;
end
//Check for last write completion.
//This logic is to qualify the last write count with the final write
//response. This demonstrates how to confirm that a write has been
//committed.
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
writes_done <= 1'b0;
//The writes_done should be associated with a bready response
else if (last_write && M_AXI_BVALID && axi_bready)
writes_done <= 1'b1;
else
writes_done <= writes_done;
end
//------------------
//Read example
//------------------
//Terminal Read Count
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
last_read <= 1'b0;
//The last read should be associated with a read address ready response
else if ((read_index == C_M_TRANSACTIONS_NUM) && (M_AXI_ARREADY) )
last_read <= 1'b1;
else
last_read <= last_read;
end
/*
Check for last read completion.
This logic is to qualify the last read count with the final read
response/data.
*/
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
reads_done <= 1'b0;
//The reads_done should be associated with a read ready response
else if (last_read && M_AXI_RVALID && axi_rready)
reads_done <= 1'b1;
else
reads_done <= reads_done;
end
//-----------------------------
//Example design error register
//-----------------------------
//Data Comparison
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
read_mismatch <= 1'b0;
//The read data when available (on axi_rready) is compared with the expected data
else if ((M_AXI_RVALID && axi_rready) && (M_AXI_RDATA != expected_rdata))
read_mismatch <= 1'b1;
else
read_mismatch <= read_mismatch;
end
// Register and hold any data mismatches, or read/write interface errors
always @(posedge M_AXI_ACLK)
begin
if (M_AXI_ARESETN == 0 || init_txn_pulse == 1'b1)
error_reg <= 1'b0;
//Capture any error types
else if (read_mismatch || write_resp_error || read_resp_error)
error_reg <= 1'b1;
else
error_reg <= error_reg;
end
// Add user logic here
// User logic ends
endmodule
