I'm planning to create a portable drum kit. I understand the idea of using piezo transducers to detect hits and play .wav drum sounds from an sd card module.
However after few research, it seems that if 2 pads are hit at the same time, the other one will be cancelled out or stopped.
Most of the drum pad DIYs are just sending MIDI signals to a pc or laptop and the laptop handles all the audio but I dont want that.
Can someone give me guidance?
The goal is to create a drum pad that can be connected to an external speaker like JBL for example through 3.5mm jack and it should handle the audio itself without the need of laptop or desktop.
My materials are:
ESP32
PCM5102
Piezos
SD card module
I don't know how they do it, but multiple simultaneous hits aren't a problem for regular electronic drums. It would be pretty hard to play the drums without both hands and at-least one foot sometimes hitting at the same time!
MIDI sends one "message" at a time, but it's fast serial so you don't hear a delay with "simultaneous" notes or drum hits.
You might need to "capture" the hit with some kind of circuit if you are using interrupts or if you can only read one input at a time. The are sample-and-hold or peak detector circuits that MIGHT work.
Once the "sound" is generated, mixing of sounds is done by summation. With digital it's sample-by-sample summation (i.e. 44,100 samples per second, or whatever your sample rate is.) Analog mixers are built-around summing amplifiers which are easy to build, but you should be mixing digitally so you only have to use one DAC.
It likely depends on the code You didn't post.
If you want more than one sound at a time, and the sounds come from an SD card file being played, then you will need multiple SD card modules. The older synthesizers had multiple tone generators to produce the "polyphonic" sound of multiple notes being played simultaneously, that was before processors became powerful enough to digitally mix sounds before being sent out through a digital-to-analog converter.
Thanks, I'm new to this and not sure if ESP32 handles all those capture by itself? Or the inputs will still be read one at a time but on a faster rate?
Mixing sounds digitally sounds like a good approach. I'll try this one out and hopefully it will work.
I don't have any code at the moment, I'll have one after DVDdoug's answer.