UART interface modules for Cocotb

GitHub repository: https://github.com/alexforencich/cocotbext-uart

Introduction

UART simulation models for cocotb.

Installation

Installation from pip (release version, stable):

$ pip install cocotbext-uart

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

$ pip install https://github.com/alexforencich/cocotbext-uart/archive/master.zip

Installation for active development:

$ git clone https://github.com/alexforencich/cocotbext-uart
$ pip install -e cocotbext-uart

Documentation and usage examples

See the tests directory and verilog-uart for complete testbenches using these modules.

UART

The UartSource and UartSink classes can be used to drive, receive, and monitor asynchronous serial data.

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

from cocotbext.uart import UartSource, UartSink

uart_source = UartSource(dut.rxd, baud=115200, bits=8)
uart_sink = UartSink(dut.rxd, baud=115200, bits=8)

To send data into a design with a UartSource, call write() or write_nowait(). Accepted data types are iterables of ints, including lists, bytes, bytearrays, etc. Optionally, call wait() to wait for the transmit operation to complete. Example:

await uart_source.send(b'test data')
# wait for operation to complete (optional)
await uart_source.wait()

To receive data with a UartSink, call read() or read_nowait(). Optionally call wait() to wait for new receive data. read() will block until at least 1 data byte is available. Both read() and read_nowait() will return up to count bytes from the receive queue, or the entire contents of the receive queue if not specified.

data = await uart_sink.recv()

Constructor parameters:

• data: data signal
• baud: baud rate in bits per second (optional, default 9600)
• bits: bits per byte (optional, default 8)
• stop_bits: length of stop bit in bit times (optional, default 1)

Attributes:

• baud: baud rate in bits per second
• bits: bits per byte
• stop_bits: length of stop bit in bit times

Methods

• write(data): send data (blocking) (source)
• write_nowait(data): send data (non-blocking) (source)
• read(count): read count bytes from buffer (blocking) (sink)
• read_nowait(count): read count bytes from buffer (non-blocking) (sink)
• count(): returns the number of items in the queue (all)
• empty(): returns True if the queue is empty (all)
• idle(): returns True if no transfer is in progress (all) or if the queue is not empty (source)
• clear(): drop all data in queue (all)
• wait(): wait for idle (source)
• wait(timeout=0, timeout_unit='ns'): wait for data received (sink)