cdc_2phase_src.md

cdc_2phase_src

Property	Value
Kind	module
RTL source	rtl/cdc/cdc_2phase.sv
Availability	Synthesizable RTL

Summary

Source-side implementation of the two-phase CDC link.

Functional Behavior

Source-side implementation of the two-phase CDC link. It carries the declared control, event, or data contract through the stated synchronizer, handshake, or Gray-pointer mechanism. Endpoint reset discards in-flight data unless the page identifies an acknowledged warm-clear path.

Suitable Applications

Use for reset release, asynchronous control/data transfer, asynchronous queues, event notification, and CDC recovery.

Parameters

The declaration below is canonical; retain the RTL-enforced parameter range.

Parameter	Declaration
DATA_WIDTH	parameter int DATA_WIDTH = 32
SYNC_STAGES	parameter int SYNC_STAGES = 2

Interface Definition

module cdc_2phase_src #(
    parameter int DATA_WIDTH  = 32,
    parameter int SYNC_STAGES = 2
) (
    input  logic                  clk_i,
    input  logic                  rst_n_i,
    input  logic [DATA_WIDTH-1:0] data_i,
    input  logic                  valid_i,
    output logic                  ready_o,
    output logic                  async_req_o,
    input  logic                  async_ack_i,
    output logic [DATA_WIDTH-1:0] async_data_o
);

Port Summary

Signal	Direction	Declaration
clk_i	input	input logic clk_i
rst_n_i	input	input logic rst_n_i
data_i	input	input logic [DATA_WIDTH-1:0] data_i
valid_i	input	input logic valid_i
ready_o	output	output logic ready_o
async_req_o	output	output logic async_req_o
async_ack_i	input	input logic async_ack_i
async_data_o	output	output logic [DATA_WIDTH-1:0] async_data_o

Integration and Use

Never use a simple synchronizer for arbitrary multi-bit data. Keep both endpoint clocks running after reset release and obey all ready/busy outputs.

cdc_2phase_src #(
    .DATA_WIDTH(DATA_WIDTH),
    .SYNC_STAGES(SYNC_STAGES)
) u_cdc_2phase_src (
    .clk_i(clk_i),
    .rst_n_i(rst_n_i),
    .data_i(data_i),
    .valid_i(valid_i),
    .ready_o(ready_o),
    .async_req_o(async_req_o),
    .async_ack_i(async_ack_i),
    .async_data_o(async_data_o)
);

Dependencies and Verification

The linked RTL source is the implementation authority and contains local assertions for unsupported parameter combinations. See docs/design.md for repository-wide CDC, reset, stream, and storage contracts, and docs/verification.md for the verification matrix.