[Ktechlab-devel] Update rates

[santiago gonzalez]

2009/9/16 Zoltan Padrah <zoltan.padrah at gmail.com>

> Yes. the logic update is done as you've written.
>
> What do you mean by unstable? Ktechlab crashes or just outputs garbage?
>

Unstable perhaps is not the proper word... i mean irregular periods, i tried
with a simple toggle led pic program at 1 Hz.
Logic update at 5e6 is 5 Mhz;
Then a pic program at 20 MHz (5MHz instruction cicle) should go real-time.
Running simulation i have a 1Hz blinking led in ktl, but sometimes go
faster, sometimes slower; anyway is a good aproach, it can run a pic at 20
MHz real-time, not very accurate, but it can.

I added an input clock singal component to the circuit... it goes at 0.25
Hz, even when is configured at 1 Hz, no matter if i use update logic 1e6 or
5e6, it goes at 0.25 Hz.

But when i run the pic the clock singal go faster...

here you can see a mini-video:
http://arcachofo.users.sourceforge.net/miweb/ktl1

I just try to understand how this work.

And i'm not sure about why the input signal does not go at 1 Hz, if it's a
problem in the component or a problem in my ktl build.


> Also I don't understand how to reproduce the problem. Set the logic update
> timer to 5e6 and then?
>

I think you can't reproduce the problem bcos with the actual gpsimprocessor
pic simulations goes very slow.
I didn't want to send you a path and send another in some days with some
other changes; if you want i send you the actual changes i have made, but i
think you should wait a time for some other changes and testing to include
it in official release (if accepted).

>
> Maybe Alan knows: how is the time in simulation managed? We should provide
> the some ways to know what is the current time in the simulation, and how
> much time has passed since the last step (for reactive elements).
>
> I think this could be a good thing.

I need some time to undertand the gpsim interface (if i finally can..), but
i think is possible to do a first aproach to real-time simulating pics in
the easy way:

-The gpsimprossesors should be updated at 5e6, may be inside logic update: a
5x loop (to not update all the logic at 5e6) .
Every gpsimprocessor should have a counter and update depending on it's
clock speed. This way only 4, 8, 12, 16, 20 MHz speeds will be accurate, but
this is just a first aproach.

-An editable propertie should be added to the pic component: clock MHz (no
idea about how to do this) this integer value is used to set the counter
value in simulator.cpp (if someday is possible to use gpsim in real-time
mode this value could be used)


2009/9/16 santiago gonzalez <santigoro at gmail.com>
>
>> I't looks to me that logic update rate (then gpsim processors) is actually
>> 1e6, then 1 MHz.. is this correct?
>>
>> What is the actual behaivor of logic update rates?
>> i think the qtimer is at 1KHz, but the loops inside every call aren't
>> sinchonized... i mean: logic updates are done 1e6 times/Sec, but not at 1us
>> steps... isn't it?, not sure about this.
>>
>> Looks to me that logic updates are done 1000 times/ms, but may be that all
>> 1000 updates could be done in the firsts 100 us, for example. Is this right?
>>
>> What is the upper limit to logic updatre rate?, tried with 5e6 with a pic
>> simulation and looks unstable.
>>
>> I don't know if this is a bug or what:
>> When i add a clock input to the circuit at 1Hz i have a 0.25 Hz signal...
>> is this a problem of the clock input component, or the timming, or is my PC?
>> Do you also have 0.25 Hz?
>>
>> The extrange thing for me is that at 5e6 i still have a 0.25 Hz signal in
>> the clock input, but if i run the pic then it goes faster but irregular...
>>
>>
>>
>>
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