avl.Env

The avl.Env module is intended to be the top-level environment for the testbench and instantiated in the cocotb test.

On top of providing the same functionalities inherited from the avl.Component class, the avl.Env module also provides the following features:

Clocks

The clock method provided by AVL wraps the cocotb Clock() method, but defines the clock in terms of frequency rather than in terms of period (a much more common way to refer to clocks in specifications).

await cocotb.start(self.clock(self.dut.clk, freq_mHz=100))

Resets

Synchroneous and asynchronous resets, of either polarity, methods are also provided.

Synchroneous resets are defined in terms of clock cycles:

await cocotb.start(self.sync_reset(self.dut.clk, self.dut.rst, cycles=10, active_high=True))

Asynchronous resets are defined in terms of time:

await cocotb.start(self.async_reset(self.dut.rst, duration=1000, units='ps', active_high=False))

Timeouts

The timeout method is used to define a timeout for the test. The purpose of the timeout is to kill unintentioanlly long tests and indicate failure.

await cocotb.start(self.timeout(duration=1000, units='ns'))

Tickers

Ticker functions are provided to provide updates on stdout at regular intervals so the user can track test progress in batch mode during low activity (such as hibernation).

Multiple tickers can run simultaneously and the message is user defined.

await cocotb.start(self.ticker(duration=1000, msg='Tempus Fugit', units='ns'))