NES APU Emulator

Emulation of the NES Audio Processing Unit.

How to use

This simpliest usage of the APU Emulator is as a simple sound generator.

#include "apu/apu.h"
using namespace apu;

Square square;
Triangle triangle;

Channel channels[] = {
    &square,
    &triangle
};

APU audio(channels, 2, DAC0_OUT);

void app_start(int, char **) {
    square.enable();
    triangle.enable();

    for (unsigned i = 0; i < 80; i++) {
        square.note(i);
        triangle.note(i+4);
        wait(0.5);
    }
}

NSF Decoding

In addition to emulating the APU, there is a class for decoding NSF files that follow the Famitracker format. The NSF decoding and APU emulation run entirely in the background, allowing other tasks to run.

#include "apu/nsf.h"
using namespace apu;

NSF nsf(DAC0_OUT);

uint8_t nsf_data[] = {
    // Put your NSF data here
};

void app_start(int, char **) {
    nsf.load(nsf_data, 0);
    nsf.start();
}

APU Hardware

The APU on the NES is an impressively simple piece of hardware that uses a combination of several hardware timers and counters to generate square waves, triangle waves, and noise.

You can find all the interesting details of the actual APU over on the Nesdev Wiki.