USRP Hardware Driver and USRP Manual  Version: 3.15.0.0-52-g0fccb00d6
UHD and USRP Manual
AXI Interface Libraries

AXI4 Stream (sim_axis_lib.vh)

Defines axis_t, an AXI Stream bus interface that implements several tasks to send and receive data on the bus.

Definition

interface axis_t #(parameter DWIDTH = 64)
                  (input clk);
  logic [DWIDTH-1:0]  tdata;
  logic               tvalid;
  logic               tlast;
  logic               tready;

modport master (output tdata, output tvalid, output tlast, input tready);
modport slave (input tdata, input tvalid, input tlast, output tready);

Operations

push_word

// Push a word onto the AXI-Stream bus and wait for it to transfer
// Args:
// - word: The data to push onto the bus
// - eop (optional): End of packet (asserts tlast)

push_bubble

// Push a bubble cycle onto the AXI-Stream bus

pull_word

// Wait for a sample to be transferred on the AXI Stream
// bus and return the data and last
// Args:
// - word: The data pulled from the bus
// - eop: End of packet (tlast)

wait_for_bubble

// Wait for a bubble cycle on the AXI Stream bus

wait_for_pkt

// Wait for a packet to finish on the bus

push_rand_pkt

// Push a packet with random data onto to the AXI Stream bus
// Args:
// - num_samps: Packet size.

push_ramp_pkt

// Push a packet with a ramp on to the AXI Stream bus
// Args:
// - num_samps: Packet size.
// - ramp_start: Start value for the ramp
// - ramp_inc: Increment per clock cycle

Compressed VITA CHDR

Defines cvita_stream_t, an AXI Stream bus interface that implements the CHDR protocol and several tasks to send and receive data on the bus.

CHDR

typedef enum logic [1:0] {
  DATA=2'b00, FC=2'b01, CMD=2'b10, RESP=2'b11
} cvita_pkt_t;

typedef struct packed {
  logic [31:0]  sid;
  logic [15:0]  length;
  logic [11:0]  seqno;
  logic         eob;
  logic         has_time;
  cvita_pkt_t   pkt_type;
  logic [63:0]  timestamp;
} cvita_hdr_t;

Operations

  • flatten_chdr_no_ts: Flatten header struct to a 64-bit bus. No timestamp.
  • unflatten_chdr_no_ts: Decode a 64-bit header and populate the cvita_hdr_t struct. No timestamp.
  • unflatten_chdr: Decode a 64-bit header and populate the cvita_hdr_t struct. Timestamp supported.

CVITA Stream Type

Definition

interface cvita_stream_t (input clk);
  axis_t #(.DWIDTH(64)) axis (.clk(clk));

push_hdr

// Push a CVITA header into the stream
// Args:
// - hdr: The header to push

push_data

// Push a word onto the AXI-Stream bus and wait for it to transfer
// Args:
// - word: The data to push onto the bus
// - eop: End of packet (asserts tlast)

push_bubble

// Push a bubble cycle on the AXI-Stream bus

pull_word

// Wait for a sample to be transferred on the AXI Stream
// bus and return the data and last
// Args:
// - word: The data pulled from the bus
// - eop: End of packet (tlast)

wait_for_bubble

// Wait for a bubble cycle on the AXI Stream bus

wait_for_pkt

// Wait for a packet to finish on the bus

wait_for_pkt_get_info

// Wait for a packet to finish on the bus and extract the header and payload statistics.

typedef struct packed {
  logic [31:0]  count;
  logic [63:0]  sum;
  logic [63:0]  min;
  logic [63:0]  max;
  logic [63:0]  crc;
} cvita_stats_t;

push_rand_pkt

// Push a packet with random data onto to the AXI Stream bus
// Args:
// - num_samps: Packet size.
// - hdr: Header to attach to packet (length will be ignored)
// - timestamp: Optional timestamp

push_ramp_pkt

// Push a packet with a ramp on to the AXI Stream bus
// Args:
// - num_samps: Packet size.
// - ramp_start: Start value for the ramp
// - ramp_inc: Increment per clock cycle
// - hdr: Header to attach to packet (length will be ignored)
// - timestamp: Optional timestamp

Memory Mapped AXI4 (sim_axi4_lib.vh)

Defines the following interfaces to group signals in the AXI4 bus. WIP: No functions or tasks implemented yet.

Address

interface axi4_addr_t #(parameter AWIDTH=32, parameter IDWIDTH=4)
                       (input clk);

  logic [IDWIDTH-1:0] id;
  logic [AWIDTH-1:0]  addr;
  logic [7:0]         len;
  logic [2:0]         size;
  logic [1:0]         burst;
  logic               lock;
  logic [3:0]         cache;
  logic [2:0]         prot;
  logic [3:0]         qos;
  logic [3:0]         region;
  logic               user;
  logic               valid;
  logic               ready;

  modport master (output id,addr,len,size,burst,lock,cache,prot,qos,valid, input ready);
  modport slave (input id,addr,len,size,burst,lock,cache,prot,qos,valid, output ready);

endinterface

Write Data

interface axi4_wdata_t #(parameter DWIDTH=64)
                       (input clk);

  logic [DWIDTH-1:0]      data;
  logic [(DWIDTH/8)-1:0]  strb;
  logic                   last;
  logic                   user;
  logic                   valid;
  logic                   ready;

  modport master(output data,strb,last,valid, input ready);
  modport slave(input data,strb,last,valid, output ready);

endinterface

Write Response

interface axi4_resp_t #(parameter IDWIDTH=4)
                       (input clk);

  logic               ready;
  logic [IDWIDTH-1:0] id;
  logic [1:0]         resp;
  logic               user;
  logic               valid;

  modport master(output ready, input id,resp,valid);
  modport slave(input ready, output id,resp,valid);

endinterface

Read Data

interface axi4_rdata_t #(parameter DWIDTH=64, parameter IDWIDTH=4)
                       (input clk);

  logic               ready;
  logic [IDWIDTH-1:0] id;
  logic [DWIDTH-1:0]  data;
  logic [1:0]         resp;
  logic               user;
  logic               last;
  logic               valid;

  modport master(output ready, input id,data,resp,last,valid);
  modport slave(input ready, output id,data,resp,last,valid);

endinterface

Meta: AXI4 Writer

interface axi4_wr_t #(parameter DWIDTH=64, parameter AWIDTH=32, parameter IDWIDTH=4)
                     (input clk);

  axi4_addr_t  #(.AWIDTH(AWIDTH), .IDWIDTH(IDWIDTH)) addr (.clk(clk));
  axi4_wdata_t #(.DWIDTH(DWIDTH))                    data (.clk(clk));
  axi4_resp_t  #(.IDWIDTH(IDWIDTH))                  resp (.clk(clk));

  modport master(output addr, output data, input resp);
  modport slave(input addr, input data, output resp);

endinterface

Meta: AXI4 Reader

interface axi4_rd_t #(parameter DWIDTH=64, parameter AWIDTH=32, parameter IDWIDTH=4)
                     (input clk);

  axi4_addr_t  #(.AWIDTH(AWIDTH), .IDWIDTH(IDWIDTH)) addr (.clk(clk));
  axi4_rdata_t #(.DWIDTH(DWIDTH), .IDWIDTH(IDWIDTH)) data (.clk(clk));

  modport master(output addr, output data);
  modport slave(input addr, input data);

endinterface