Sunday, June 13, 2010

Digital Logic in Reason: Updated Flipflop & Counter

Thanks to everyone here and in various other places for the great feedback on my 16 bit counter. I completely appreciate that this 'invention' is somewhat esoteric at this point - it's not even obvious to me what one might actually use it for. However I do have some ideas brewing and that's led me to slightly refine my flipflop slightly.

The new version (0.0.3) has more consistent assignment of the input and output ports, with a "pass-thru" output port for each of the three (clock, reset, data) input signals. The signal on the input port simply appears on the output port, immediately and unchanged. This allows you to easily chain together multiple flipflops without having to create large banks of CV splitters.

The main state or "Q" output has been moved to CV Out4. The mandatory wire between Audio Out1 and Audio In1 remains - remember that you have to add this manually since it is not saved as part of the .thor patch.

The "beep" button can be used to help debug the operation of the flipflop - to use this, connect a wire from Audio Out4 to a mixer channel, then click the "beep" button and you should hear a beep on each rising clock edge. The tone changes depending on whether the Q output is high or low.

To demonstrate that this flipflop still works, I have included a test-bench and an updated version of the 16-bit counter. Both use version 0.0.3 of the flipflop throughout. I've also included the 4-bit counter combi patch.

I have yet to analyse the setup- and hold-times for this device. The internal 7.9ms delay will definitely limit the maximum speed that this device can run at. If I used an external DDL-1 I could reduce the delay to 1ms but that would mean either putting the entire device inside a combinator (which I want to avoid for as long as possible), or ensuring an external DDL-1 is hooked up to every flipflop.

There was also a slight bug in the AND2 device - this has been fixed in the files above (bipolar and2-0.0.2).

Stay tuned for more digital logic posts.

The examples in this article require Reason 4 or newer.

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