APB interface modules for Cocotb

GitHub repository: https://github.com/daxzio/cocotbext-apb

Introduction

APB simulation models for cocotb.

Installation

Installation from pip (release version, stable):

$ pip install cocotbext-apb

Installation from git (latest development version, potentially unstable):

$ pip install https://github.com/daxzio/cocotbext-apb/archive/main.zip

Installation for active development:

$ git clone https://github.com/daxzio/cocotbext-apb
$ pip install -e cocotbext-apb

Documentation and usage examples

See the tests directory for complete testbenches using these modules.

APB Bus

The APBBus is used to map to a JTAG interface on the dut. Class methods from_entity and from_prefix are provided to facilitate signal default name matching.

Required:

• psel
• pwrite
• paddr
• pwdata
• pready
• prdata

Optional:

• pstrb
• pprot
• pslverr

APB Master

The ApbMaster class implement a APB driver and is capable of generating read and write operations against APB slaves.

To use these modules, import the one you need and connect it to the DUT:

from cocotbext.apb import ApbMaster, ApbBus

bus = ApbBus.from_prefix(dut, "s_apb")
apb_driver = ApbMaster(bus, dut.clk)

The first argument to the constructor accepts an ApbBus object. These objects are containers for the interface signals and include class methods to automate connections.

Once the module is instantiated, read and write operations can be initiated in a couple of different ways.

Additional optional arguments for ApbMaster

• period: Clock frequency period of tck, default 100
• units: Clock units, default ns
• logging_enabled: Logging enable, default True

Methods

• add_device(device): Add device to jtag chain, must be of type JTAGDevice
• set_reset(num): Reset for num if trst is present in JTAGBus, raise warning if trst is not present
• reset_finished(): Asyn wait until reset is finished
• reset_fsm(): Send 5 tck pulses while tms is held high in JTAGBus, this resets the finite state machine inside a JTAG TAP
• send_val(addr, val, device, write): Send addr to device (default: 0). The val is used to write if write is True or verify against if write is False
• write_val(addr, val, device=0): Write val to addr of device (default: 0).
• read_val(addr, val=None, device=0): Read from addr of device (default: 0). If val present verify against returned value.
• read_idcode(device): Read device number device and confirm it matched the IDCODE set for that device