You can hear the result here :
https://soundcloud.com/gaetino/poumtchack
First of all, you will have to wire a SD card to the SPI port, and making an audio out on the Arduino. Please refer to this post if you don't know how to connect the hardware :
http://groovuino.blogspot.com/2013/03/the-goal-is-to-build-groovebox-using.html
On the SD card, you will transfer 2 one-shot wave files (44 kHz), named "kick1.wav" and "snare1.wav".
Download groovuino library and SdFat lib :
https://github.com/Gaetino/Groovuino
https://code.google.com/p/sdfatlib/
Then put them in your favorite arduino library repository.
As usual, we'll begin the code by importing libraries :
#include <SdFat.h>
#include <sampler.h>
#include <timer.h>
#include <sampler.h>
#include <timer.h>
Now instanciate a Sd and a sampler object :
SdFat sd;
Sampler sampler;
Sampler sampler;
To make the beat, we'll use a simple timer :
int to = 0;
Now the setup method to initialize our data :
void setup()
{
// Start the audio engine
startTimer(TC1, 1, TC4_IRQn, 44100);
analogWrite(DAC1,0);
sd.begin(chipSelect, SPI_FULL_SPEED);
sampler.init();
}
{
// Start the audio engine
startTimer(TC1, 1, TC4_IRQn, 44100);
analogWrite(DAC1,0);
sd.begin(chipSelect, SPI_FULL_SPEED);
sampler.init();
}
We'll use the loop() method to compute the beat, and to fill the wave buffer if necessary.
Of course, if you want to make a groovebox, you will need another timer to get the beat and trigger the samples.
void loop()
{
if(to>100000)
{
to=0;
// POUM
sampler.load("kick1.wav");
sampler.splay(100,1);
}
if(to==50000)
{
// TCHACK
sampler.load("snare1.wav");
sampler.splay(100,1);
}
sampler.buffill();
delayMicroseconds(10);
to++;
}
{
if(to>100000)
{
to=0;
// POUM
sampler.load("kick1.wav");
sampler.splay(100,1);
}
if(to==50000)
{
// TCHACK
sampler.load("snare1.wav");
sampler.splay(100,1);
}
sampler.buffill();
delayMicroseconds(10);
to++;
}
And finally, as usual, the audio engine :
void TC4_Handler()
{
TC_GetStatus(TC1, 1);
// 2048 is the 0 value of audio out.
int16_t ulOutput=2048;
sampler.next();
ulOutput += sampler.output();
if(ulOutput>4095) ulOutput=4095;
dacc_write_conversion_data(DACC_INTERFACE, ulOutput);
}
{
TC_GetStatus(TC1, 1);
// 2048 is the 0 value of audio out.
int16_t ulOutput=2048;
sampler.next();
ulOutput += sampler.output();
if(ulOutput>4095) ulOutput=4095;
dacc_write_conversion_data(DACC_INTERFACE, ulOutput);
}
That's it. If all is good, you can hear a "poum-tchack".
