The different frequency makes a different tone. Since my programming skills are far from perfect, ive run into some problems hacking the attached analogcc code from s2midi to accept multiple pots on different analog pins. If generating a square wave of the specified frequency (and 50 duty cycle) on the positive pin, the piezo buzzer generates tones. The thing is, I want to use around 16 pots and 16 switches. Although there was some latency it was barely noticable. Ive succesfully connected 1 pot using a arduino mega, s2midi and midi yoke to ableton live. Ive been researching the possibility’s of serial to midi data sending and this has proven to be extremely usefull. MIDI Output at ITP Physical Computing Lab.When I’ve done this before, I used an input opamp to convert the analog signal to digital (thus doing thresholding in the analog domain) and then used interrupts to get very accurate force measurements. In the code this is represented by reading the analog value and if it’s over the threshold, wait until it drops down again, counting all the while. Kind of like this:īy measuring the time it takes for that first big jolt to cross a threshold, you can get an idea as how big the force was. When piezo elements are struck, their output voltage rings, sort of like a bell. The final trick is measuring impact force on a piezo. The benefit is that you no longer need a resistor to +5V and the effort to wire up each additional button is much lower. This may seem counter-intuitive, doing a digitalWrite() on an input pin, but it’s how the AVR works. This is because the internal pull-ups in Arduino’s AVR chip are turned on with a “ digitalWrite(pin,HIGH)“. The next tricky bit is that the switches in the above schematic don’t need pull-up resistors. Once that is done, a complete three-byte MIDI note-on message can be sent with three “ Serial.print(val,BYTE)” commands. This is easily done with “ Serial.begin(31250)“. First is that to implement a MIDI interface, all you really need is the ability to send serial data at 31,250 bps. The code has a few tricks that may not be immediately obvious. The 5.1v zener diode is there to insure any large voltages don’t make it into the Arduino and blow it out. (Note: depending on what kind of MIDI connector you’re usign (jack or cut-off cable), you may need to swap the connections to MIDI pins 4 & 5).įor the piezo input, the 1M resistor is to bleed off the voltage generated by the piezo when it is struck. The hardware is an Arduino board with a MIDI jack, a few buttons, and two piezos attached to it. Hide piezo sensors around the house during your Halloween party to trigger scary sounds when people walk around! Here’s a quick project using techniques from this week’s class that turns an Arduino board and a few buttons and piezos into a MIDI drum kit or scary sound trigger. Arduino MIDI Drum Kit and Spooky Sound Trigger Click above for a larger view of the badge. At the end of the class, Mark of Machine Project bestowed upon each of the students a merit badge. The notes for the fourth and final class are up on the Spooky Arduino class page.
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