view projects/basic_analog_output/render.cpp @ 45:579c86316008 newapi

Major API overhaul. Moved to a single data structure for handling render functions. Functionally, generally similar except for scheduling within PRU loop function, which now uses interrupts from the PRU rather than polling. This requires an updated kernel.

/*
 * render.cpp
 *
 *  Created on: Oct 24, 2014
 *      Author: parallels
 */


#include "../../include/render.h"
#include "../../include/Utilities.h"
#include <rtdk.h>
#include <cmath>

// Set range for analog outputs designed for driving LEDs
const float kMinimumAmplitude = (1.5 / 5.0) * MATRIX_MAX;
const float kAmplitudeRange = MATRIX_MAX - kMinimumAmplitude;

float gFrequency;
float gPhase;
float gInverseSampleRate;

// initialise_render() is called once before the audio rendering starts.
// Use it to perform any initialisation and allocation which is dependent
// on the period size or sample rate.
//
// userData holds an opaque pointer to a data structure that was passed
// in from the call to initAudio().
//
// Return true on success; returning false halts the program.

bool initialise_render(int numMatrixChannels, int numAudioChannels,
					   int numMatrixFramesPerPeriod,
					   int numAudioFramesPerPeriod,
					   float matrixSampleRate, float audioSampleRate,
					   void *userData)
{
	// Retrieve a parameter passed in from the initAudio() call
	gFrequency = *(float *)userData;

	if(numMatrixFramesPerPeriod == 0) {
		rt_printf("Error: this example needs the matrix enabled\n");
		return false;
	}

	gInverseSampleRate = 1.0 / matrixSampleRate;
	gPhase = 0.0;

	return true;
}

// render() is called regularly at the highest priority by the audio engine.
// Input and output are given from the audio hardware and the other
// ADCs and DACs (if available). If only audio is available, numMatrixFrames
// will be 0.

void render(int numMatrixFrames, int numAudioFrames, float *audioIn, float *audioOut,
			uint16_t *matrixIn, uint16_t *matrixOut)
{
	for(int n = 0; n < numMatrixFrames; n++) {
		// Set LED to different phase for each matrix channel
		float relativePhase = 0.0;
		for(int channel = 0; channel < gNumMatrixChannels; channel++) {
			float out = kMinimumAmplitude + kAmplitudeRange * 0.5f * (1.0f + sinf(gPhase + relativePhase));
			if(out > MATRIX_MAX)
				out = MATRIX_MAX;

			analogWrite(channel, n, out);

			// Advance by pi/4 (1/8 of a full rotation) for each channel
			relativePhase += M_PI * 0.25;
		}

		gPhase += 2.0 * M_PI * gFrequency * gInverseSampleRate;
		if(gPhase > 2.0 * M_PI)
			gPhase -= 2.0 * M_PI;
	}
}

// cleanup_render() is called once at the end, after the audio has stopped.
// Release any resources that were allocated in initialise_render().

void cleanup_render()
{

}