# APB Protocol Definition — UVM TB Generator
protocol: apb
description: Advanced Peripheral Bus (AMBA 3 APB)
tags: [bus, memory-mapped, synchronous, low-power]

interface_template:
  signals:
    - {name: psel,    direction: input,  width: 1, description: Select}
    - {name: penable, direction: input,  width: 1, description: Enable}
    - {name: paddr,   direction: input,  width: 32, description: Address}
    - {name: pwrite,  direction: input,  width: 1, description: Write (1) / Read (0)}
    - {name: pwdata,  direction: input,  width: 32, description: Write data}
    - {name: prdata,  direction: output, width: 32, description: Read data}
    - {name: pready,  direction: output, width: 1, description: Ready}
    - {name: pslverr, direction: output, width: 1, description: Slave error}

config_parameters:
  - {name: ADDR_WIDTH, type: int, default: 32}
  - {name: DATA_WIDTH, type: int, default: 32}

register_template:
  - name: APB_CTRL
    address: 0x00
    access: rw
    fields:
      - {name: enable, bits: 0, description: Core enable}
  - name: APB_DATA
    address: 0x04
    access: rw
    fields:
      - {name: data, bits: 31:0, description: Data value}

sequence_template:
  name: apb_sequence
  body: |
    // APB write sequence
    paddr = addr;
    pwdata = data;
    pwrite = 1;
    psel = 1;
    @(posedge clk);
    penable = 1;
    wait(pready);
    @(posedge clk);
    psel = 0; penable = 0;

coverage_template:
  - name: apb_cg
    type: covergroup
    items:
      - {name: cg_op, type: coverpoint, expression: pwrite}