Using the video generator to gerenate frequencies

godzich

Hi,

Still a rookie concerning the Prop, but learning all the time... A very pleasant learning curve

Can someone sched some light on the video generator that is embedded in each propeller. It is more or less like a blakc box, very little info exists of its inner construction. Or then I'm not good in looking up information...

1. Where to find a document that explains its internal secrets (just little like the AN-001 - for the counters)??

2. Would it be possible to generate a toggling output at some higher frequency - just using the video generator AND without reloading it in software?

I am looking at an application where I already have both counters (A,B) in other use, but need to generate additionally a frequency on an output pin. This is - withing the SAME COG, and without software intervention (waiting for reloading the video register). If the video generator would be built so that the pattern repeats itself then this would be possible - or ?

Cheers,

Christian

kwinn

As far as I know the video generator must be continuously reloaded with data using waitvid (after every 32 pixels out) to produce a signal. If the frequency of the output is not too high it may be possible to interleave the waitvid instructions within the program to accomplish this, but it would be simpler to use a counter from another cog.

ericball

The Datasheet has additional information on the video generator. There was also this thread: http://forums.parallax.com/showthread.php?t=124349

Unfortunately, the video generator uses Counter A as the primary frequency reference (with Counter B as a modulator for broadcast). So if you've already used both counters, the video generator won't give you a third frequency output. Your code will also need to update the generator periodically (via WAITVID).

That being said, the video generator can be used to generate more than video.