Archive for February, 2008

Guitar Rising

stevecooley | February 7, 2008 in tools | Comments (0)

YES. NOW. WANT.


GuitarRising
by jakeparks
Share this:
Share this page via Email Share this page via Stumble Upon Share this page via Digg this Share this page via Facebook Share this page via Twitter

DIY drum triggers… reading the sensor scientifically

stevecooley | February 2, 2008 in news | Comments (24)

I’ve learned so much about piezos, microcontrollers, serial data capture, graphing. All from people I’ve never even met in person. Tod E. Kurt’s work on the Arduino MIDI drum kit lead me to want to replicate the project for myself, and I’ve been running into some very tricky problems with the sensors triggering samples two or three times. I got a boost of confidence that I was detecting a real problem thanks to the fine work done by mschaff’s Ardrumo project. Now, thanks very much to Tom Igoe’s article on Sensor Graphing using a tiny arduino sketch, the terminal, and grapher.app, I can actually scientifically diagnose the reason why this is happening.

Using the DIY kick pedal that I’ve been working on…
Img 0218

I was able to capture and graph the data that the sensor is outputting. Here are a few screenshots of the highlights:

Grapherscreensnapz001

This first screenshot shows a good peak, right at the beginning of the strike. Then the ringing begins. If, for instance, I had the threshold set to 500, this would trigger not just one, but *three* midi notes. Ok, but what if I had set the threshold to closer to 750? a big problem with that is that I’m losing a lot of the dynamic quality of the kick pedal. I’d have to hammer on it just to register above the minimum value, and then there’s no way to play it quietly. Every kick would end up being 750 or higher.

But wait, there’s more! Here’s another reading:

Grapherscreensnapz002
Wow, so even if I had set the threshold to 750, I’d *STILL* get three notes off this one kick pedal strike! And then just to mix it up even more:

Grapherscreensnapz003
Here is yet another pattern of the data. a short hop at the beginning well under a reasonable threshold of 250, and then a reading over 500, and then an even higher reading on the “second wave”…

So, the question still remains… how to get a clean sensor reading? Here’s my current idea:

Drum Trigger Sensor Reading
Charting it out helps. Now I just need to try to write the code so it follows this to test it out. Comments and suggestions are welcome. :)

Technorati Tags: , , , , , , , ,

Share this:
Share this page via Email Share this page via Stumble Upon Share this page via Digg this Share this page via Facebook Share this page via Twitter