Electro Harmonix are mainly known for creating guitar pedals now but back in the 80's they also had a range of synthesizers and similar hardware. The Crash Pad is one of their instruments that was available during this time and is essentially a single trigger drum machine that creates sweeping tones on each hit. Now it is back with the same level of control and connectivity that you had in the original but in a much smaller box.
After a few minutes of using the Crash Pad you will find some very cool oscillating tones that match your sound. But if you play a bit more and dig a bit deeper you can create cool analogue like cymbal and snare sounds just using the built in sweep filter. It does take time to perfect the sound but when you hit the sweet point it sounds superb in the most 80's way possible.
Run Off A Sequencer.
While it does have a trigger on the front you are most likely going to run this off of some kind of sequencer like the EHX CLockworks Rhythm Generator. By feeding this in to the system you can trigger it remotely using any analog expression/CV device once you have created the tone you want.
Here's what Electro Harmonix say about the Crash Pad
EHX's rich history was marked by many revolutionary pedals but one of our most distinctive lines was a group of analog drum synthesizers that included the Crash Pad.
Like the original from 1980, the new Crash Pad can create an array of drum sounds and other-worldly oscillation sweeps, as well as process external sounds thru its resonant filter. Plus, it's been updated to respond to expression pedal/CV input for external control over the filter in real-time.