annotate examples/11-Extras/stepper/render.cpp @ 556:ce391098f321 prerelease tip

THIS PROJECT HAS MOVED TO https://github.com/BelaPlatform/bela

/*
 ____  _____ _        _    
| __ )| ____| |      / \   
|  _ \|  _| | |     / _ \  
| |_) | |___| |___ / ___ \ 
|____/|_____|_____/_/   \_\

The platform for ultra-low latency audio and sensor processing

http://bela.io

A project of the Augmented Instruments Laboratory within the
Centre for Digital Music at Queen Mary University of London.
http://www.eecs.qmul.ac.uk/~andrewm

(c) 2016 Augmented Instruments Laboratory: Andrew McPherson,
  Astrid Bin, Liam Donovan, Christian Heinrichs, Robert Jack,
  Giulio Moro, Laurel Pardue, Victor Zappi. All rights reserved.

The Bela software is distributed under the GNU Lesser General Public License
(LGPL 3.0), available here: https://www.gnu.org/licenses/lgpl-3.0.txt
*/


#include <Bela.h>

const int kStepLengthSlow = 1000;
const int kStepLengthFast = 500;

int gStepLengthSamples = kStepLengthSlow;

const int gPinA1 = P8_27;
const int gPinA2 = P8_28;
const int gPinB1 = P8_29;
const int gPinB2 = P8_30;
const int gPinServo = P9_16;

int gStepCounter = 0;
int gPhase = 0;

int gServoCounter = 0;


enum {
	kStateMoveRight1 = 0,
	kStateMoveLeft1,
	kStateMoveRight2,
	kStateMoveLeft2,
	kStateMoveRight3,
	kStateMoveLeft3,
	kStateSpin,
	kStateMax
};

int gState = 0;
int gStateCounter = 0;

// setup() 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 setup(BelaContext *context, void *userData)
{	
	// This project makes the assumption that the audio and digital
	// sample rates are the same. But check it to be sure!
	if(context->audioFrames != context->digitalFrames) {
		rt_printf("Error: this project needs the audio and digital sample rates to be the same.\n");
		return false;
	}
	
	pinMode(context, 0, gPinA1, OUTPUT);
	pinMode(context, 0, gPinA2, OUTPUT);
	pinMode(context, 0, gPinB1, OUTPUT);
	pinMode(context, 0, gPinB2, OUTPUT);
	pinMode(context, 0, gPinServo, OUTPUT);
		
	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(BelaContext *context, void *userData)
{
	for(unsigned int n = 0; n < context->audioFrames; n++) {
		if(gPhase == 0 || gPhase == 1) {
			digitalWriteOnce(context, n, gPinB1, HIGH);
			digitalWriteOnce(context, n, gPinB2, LOW);
		}
		else {
			digitalWriteOnce(context, n, gPinB1, LOW);
			digitalWriteOnce(context, n, gPinB2, HIGH);			
		}
		
		if(gPhase == 1 || gPhase == 2) {
			digitalWriteOnce(context, n, gPinA1, HIGH);
			digitalWriteOnce(context, n, gPinA2, LOW);
		}
		else {
			digitalWriteOnce(context, n, gPinA1, LOW);
			digitalWriteOnce(context, n, gPinA2, HIGH);			
		}
		
		if(--gServoCounter > 0) 
			digitalWriteOnce(context, n, gPinServo, HIGH);
		else
			digitalWriteOnce(context, n, gPinServo, LOW);
		
		if(++gStepCounter >= gStepLengthSamples) {
			gStateCounter++;
			
			switch(gState) {
				case kStateMoveRight1:
				case kStateMoveRight2:
				case kStateMoveRight3:
					gPhase = (gPhase + 1) & 3;
					break;
				case kStateMoveLeft1:
				case kStateMoveLeft2:
				case kStateMoveLeft3:				
					gPhase = (gPhase + 3) & 3;	
					break;
				case kStateSpin:
					gPhase = (gPhase + 1) & 3;
					break;		
			}
			
			if(gState == kStateSpin) {
				if(gStateCounter >= 48) {
					gStateCounter = 0;
					gState = 0;
					gStepLengthSamples = kStepLengthSlow;
				}				
			}
			else {
				if(gStateCounter >= 16) {
					gStateCounter = 0;
					gState++;
					if(gState & 1)
						gServoCounter = 120;
					else
						gServoCounter = 80;
					if(gState == kStateSpin)
						gStepLengthSamples = kStepLengthFast;
				}
			}
			
			gStepCounter = 0;
		}
	}
}

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

void cleanup(BelaContext *context, void *userData)
{
	
}