I would like to build a midi drum pad assembly that can be triggered with sticks like the Alesis Sample Pad Pro or a Rolland Octapad only with at least 30 and up to 42 pads, also foot pedals for hi hat, bass drum and triggering events. I have built pedals using a piezo for the bass drum and a FSR for the hi hat which work great with the Sample Pad Pro. The sample pad only has 8 pads and cannot change kits fast enough for live performance, since I'm using a DAW for all samples and instruments etc. I only need a trigger interface. Is this doable with the Tennsy and could it be used with Ableton live? If so do piezos need analog inputs or is there a way to use the digital inputs? If this is possible any help would be greatly appreciated.
drum pad brain
- Thread starter seayaker
- Start date
- Status
PaulStoffregen
Well-known member
It depends on whether you want "velocity sensitive". For that, analog inputs are needed. Generally it's quite difficult to use more than 1 signal per analog pin. Techniques like the 74HC4051 mux chips work well for knobs and sliders on DJ controllers, but for fast signals like trying to capture the peak of a fast transient from a piezo, the slowness of cycling through so many inputs is problematic.
If you need this to be all analog "velocity sensitive", I'd say this is probably going to take at least 2 of the larger Teensy boards (each appearing as a separate MIDI device) to get enough analog inputs, and enough speed to sample them all and detect useful characteristics of the waveforms.
If you need this to be all analog "velocity sensitive", I'd say this is probably going to take at least 2 of the larger Teensy boards (each appearing as a separate MIDI device) to get enough analog inputs, and enough speed to sample them all and detect useful characteristics of the waveforms.
Thanks for the reply, I could live with 24 velocity sensitive pads if I could also make cc switches. If it will work with Ableton live, I can switch drum racks on the fly and control everything with drum sticks and foot pedals so I don't have to put a stick down and press a button. I took a nano pad apart to see if I could modify the pads to respond to sticks with no luck. The quick bounce of the stick does not trigger that type easily. Unless there's another type of sensor that would trigger with drum sticks, I guess I have to use piezos.
Then there's the pedals, the bass drum and any cc switches are no problem but the hi hat has to change the designated pad to 3 different samples, open, half open and closed. I assume there is voltage in the circuit that is lowered by the FSR (force sensing resistor) which determines which sample gets played. The foot splash is triggered by a fast tap and quick release and the chick sound triggered when pedal down hard. The FSR is all that is necessary for the pedal when used with the Sample pad, I was hoping to be able to use it switch it to control other parameters such as a pitch control with certain drum racks. I'd like to use just 1 Teensy but I will buy 2 if necessary and I would really appreciate any help as I'm just an old drummer and know nothing about programming.
Then there's the pedals, the bass drum and any cc switches are no problem but the hi hat has to change the designated pad to 3 different samples, open, half open and closed. I assume there is voltage in the circuit that is lowered by the FSR (force sensing resistor) which determines which sample gets played. The foot splash is triggered by a fast tap and quick release and the chick sound triggered when pedal down hard. The FSR is all that is necessary for the pedal when used with the Sample pad, I was hoping to be able to use it switch it to control other parameters such as a pitch control with certain drum racks. I'd like to use just 1 Teensy but I will buy 2 if necessary and I would really appreciate any help as I'm just an old drummer and know nothing about programming.
It's a just a thought, but if you can spare both an analog and digital pin per velocity sensitive input : pass the signal to a comparator with a low threshold to trigger an interrupt when the pad it struck. Then analog read that pin, perhaps even charge a small cap if you dont care for the decay of the wave. That might help get around problems with polling inputs.
So I'd like to to get started and order the parts. Just to be sure, I can do everything with 2 Teensys and enough piezos? Will Ableton recognize it? Any problem making a hi hat peddle with a FSR?
PaulStoffregen
Well-known member
Just to be realistic, you're going to be learning as you go. Definitive answers about exactly what you'll need for such a large project just aren't 100% certain at such an early stage. Two of the larger Teensy boards ought to be able to do what you've described, but please consider this description isn't perfectly clear. I think I know what you want to do, but I am using some imagination to fill in likely answers for a number of the technical decisions you'll likely make along the way. Perhaps things will go somewhat differently. Nobody can say for sure.
I do believe you should start with File > Examples > Teensy > USB_MIDI > Buttons. Even before you buy anything, you can download Arduino and Teensyduino and look at this example code. Yes, it's only buttons connected to digital pins. That's the place to start. Get the MIDI stuff working. Learn how to print to the serial monitor so you see non-MIDI info about what the code is doing. From there, you'll probably branch out to experimenting with sensors. Please resist the urge to wire up dozens of sensors before you've experimented with just one.
When you're learning as you go, the path to success involves many small steps and lots of incremental progress.
I do believe you should start with File > Examples > Teensy > USB_MIDI > Buttons. Even before you buy anything, you can download Arduino and Teensyduino and look at this example code. Yes, it's only buttons connected to digital pins. That's the place to start. Get the MIDI stuff working. Learn how to print to the serial monitor so you see non-MIDI info about what the code is doing. From there, you'll probably branch out to experimenting with sensors. Please resist the urge to wire up dozens of sensors before you've experimented with just one.
When you're learning as you go, the path to success involves many small steps and lots of incremental progress.
Excellent advice! I can afford a $20 mistake here and there but $100s not so much. I'm still in the planning stage so I will try the code first. Can't help but be stoked to build this because it's nothing that doesn't already exist so it must be doable.
- Status