Re: [myhdl-list] Re: Problems inferring RAM when it is buried in system

[Tom D. <td...@di...>]

George Pantazopoulos wrote:

>  It seems that some unit tests I would want to do require a human in the
>loop. Examples would be verifying that sounds are being produced, or
>certain messages displayed on an LCD screen. How do these fit into this
>flow, if the flow is to be automated?
>  
>

I've learned everything I know about unittests from the MyHDL manual, 
check out the unittest section:

http://www.jandecaluwe.com/Tools/MyHDL/manual/unittest.html

You need to figure out a test strategy for your system. I would not make 
a single module that I didn't test before combining it with other 
modules though and unittests make a great way to thoroughly test a 
module. And provide a means to retest later when new features are added 
or modified.

It is much easier to troubleshoot a problem in simulation than in 
hardware, so it well worth your while to create a simulation environment 
that more closely represents the real system.

>  Rather than unit tests, I've been doing test-benches and viewing the
>resulting waveforms with gtkwave. I'm running into the probem quite
>often that my system looks great in simulation, but does not work
>correctly (or at all sometimes) after being synthesized.
>  
>
Waveform viewing is very tedious and is difficult to really verify 
operation. I only look at waveforms out of desperation to help diagnose 
a problem.

>  I'd like to add unit tests to my flow, but I could really use some
>guidance and example code for this. What should I unit test? Should a
>unit test always be completely automated, etc?
>  
>
Like I said before, I would unittest everything and automate it all. 
Since you are testing in python, it becomes fairly simple to automate.

>  Could you tell me about co-simulation? I've had a tough time browsing
>the web looking for non-expert information about it. How would I go
>about doing this with myHDL and other free/low-cost tools?
>  
>
Co-simulation here refers to a mixed MyHDL and HDL simulation 
environment. Again check the manual for a great source of information:

http://www.jandecaluwe.com/Tools/MyHDL/manual/cosim.html


Tom