cocotb_with_ghdl/tests/tb_uarttx.py

import logging
import random
import cocotb
import wavedrom
from Uart import UartDriver, UartReceiver
from Vai import VaiDriver, VaiReceiver
from cocotb.clock import Clock
from cocotb.triggers import FallingEdge, RisingEdge, Timer, ReadOnly


# Reset coroutine
async def reset_dut(reset_n, duration_ns):
    reset_n.value = 0
    await Timer(duration_ns, units="ns")
    reset_n.value = 1


@cocotb.test()
async def test_uarttx(dut):
    """ First simple test """

    clkedge = RisingEdge(dut.clk_i)

    # Connect reset
    reset_n = dut.reset_n_i

    # Instantiate VAI driver
    vai_driver = VaiDriver(dut.clk_i, dut.data_i, dut.valid_i, dut.accept_o)
    # Instantiate UART receiver
    uart_receiver = UartReceiver(dut.tx_o, dut.clk_i, 10, 8, True);

    # Drive input defaults (setimmediatevalue to avoid x asserts)
    dut.data_i.setimmediatevalue(0)
    dut.valid_i.setimmediatevalue(0)

    clock = Clock(dut.clk_i, 10, units="ns")  # Create a 10 ns period clock
    cocotb.start_soon(clock.start())  # Start the clock

    # Execution will block until reset_dut has completed
    dut._log.info("Hold reset")
    await reset_dut(reset_n, 100)
    dut._log.info("Released reset")

    # Test 10 UART transmissions
    for i in range(10):
        await clkedge
        val = random.randint(0, 255)
        await vai_driver.send(val)
        rec = await uart_receiver.receive();
        assert rec == val, "UART sent data was incorrect on the {}th cycle".format(i)