comparison projects/basic_analog_input/render.cpp @ 269:ac8eb07afcf5

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+/*
+ ____  _____ _        _    
+| __ )| ____| |      / \   
+|  _ \|  _| | |     / _ \  
+| |_) | |___| |___ / ___ \ 
+|____/|_____|_____/_/   \_\.io
+
+ */
+
 /*
  * render.cpp
  *
  *  Created on: Oct 24, 2014
  *      Author: parallels
  */
 
+/**
+\example 3_analog_input
+
+Connecting potentiometers
+-------------------------
+
+This sketch produces a sine tone, the frequency and amplitude of which are 
+affected by data received on the analog pins. Before looping through each audio 
+frame, we declare a value for the frequency and amplitude of our sine tone 
+(line 55); we adjust these values by taking in data from analog sensors 
+(for example, a potentiometer).
+
+The important thing to notice is that audio is sampled twice as often as analog 
+data. The audio sampling rate is 44.1kHz (44100 frames per second) and the 
+analog sampling rate is 22.05kHz (22050 frames per second). On line 62 you might 
+notice that we are processing the analog data and updating frequency and 
+amplitude only on every second audio sample, since the analog sampling rate is 
+half that of the audio.
+
+Note that the pin numbers are stored in the variables `gAnalogInputFrequency` and 
+`gAnalogInputAmplitude`. These are declared in the main.cpp file; if you look in 
+that file you will see that they have the values of 0 and 1. Bear in mind that 
+these are analog input pins which is a specific header!
+*/
 
 #include <BeagleRT.h>
 #include <Utilities.h>
 #include <rtdk.h>
 #include <cmath>

 //
 // 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(BeagleRTContext *context, void *userData)
 {
 	if(context->analogFrames == 0 || context->analogFrames > context->audioFrames) {
 		rt_printf("Error: this example needs analog enabled, with 4 or 8 channels\n");