Castle Patching 002: Digital Sample and Hold

At the end of this exercise you should be able to *pixelate a digitized video source. This exercise expands upon the previous exercise; Castle Patching 001: Digitizing Luma Video Sources. I call this a digital sample and hold because like an analog sample and hold this will hold the 3-bit binary value at the D0-D2 inputs at the rising edge of an incoming clock signal until the next clock pulse comes in. The held value appears at the D0-D2 outputs.
Tools needed for this exercise are: Castle ADC, Castle DAC, Castle Clock VCO (or other VCO), Castle D Flip Flops, and a video source.

*I say pixelate, because the effect looks similar, but unlike pixels which are rectangular or square, this effect is on a per line basis. It also isn’t constrained to a global pixel clock, you can vary the clock at video rates and get unusual pixel geometry.

Take the patch from exercise 001, and instead of going from the ADC to the DAC, go from ADC outputs D0-D2 and put them in to the D0-D2 inputs of the D Flip Flops. Set the Castle Clock VCO to HI Range, and H sync. Set the frequency at its highest value to start. Take the output of the Clock VCO to the CLK input of the D Flip Flops. Take the D Flip Flop outputs D0-D2 in to the DAC D0-D2 inputs. The DAC output will go to your video output. Now have fun varying the Clock with CV inputs, or rearranging D0-D2 in any order. This completes the Castle Digital Sample and Hold patch.

This was probably the most exciting effect for me when I was first designing the Castle series. The idea of varying the size and shape of a pixel seemed so interesting, it would open up a completely new look beyond video games. Once I saw the effect come alive on screen I knew it would be something I would use time and again in my patches.

Patch picture: Clock with no modulation

Patch picture: Clock with modulation



So I’m trying to get this patch to work. I can get Lesson 001 to work - the “posterized” (sorta) diamond. But when I try to make the Lesson 002 patch work, here’s what I get:

I’ve checked and rechecked my patch, and I believe I’ve followed directions - though you’ll notice that in order to get a picture at all I have to turn the Frequency knob on the Clock module way down. Any ideas what’s up (I couldn’t get a really nice picture of my patch panel, sadly…)?

The pink cable all the way on the left is coming from the VC’s diamond ramp. The green cable peeling off to the right out of the Dual DAC is going back to VC.

Any ideas what I’m doing incorrectly? Thanks!

How is the clock VCO receiving sync? Is it on the same power bus as the Cortex?

I’ve got it working! the problem was actually twofold. First - I didn’t have the VC and the Castle in the same case, so they weren’t sharing sync. Second, my Castle Clock module was built with an incorrect part installed. So I’ve pulled it from the case until I can look at it - in the meantime I’m just using the LZX Waveform Generator to make the magic happen with Castle. It’s amazing!

Thanks for reaching out to help.