Creating a Library-Object

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rootgordon

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Hello everyone,

I've been digging into the Audio-Library to create my own object to use with a teensy3.2 + Audio-Shield.

Naturally I'm running into problems, so I've gotten to the point where I've reduced my update function to the bare minimum:

AudioEffectDummy.cpp:
Code: 
#include "AudioStream.h"
#include "AudioEffectDummy.h"
#include "spi_interrupt.h"

void AudioEffectDummy::update(void) {
audio_block_t *inBlock ;
inBlock = receiveReadOnly() ;
transmit(inBlock, 0) ;
release(inBlock) ;
}

AudioEffectDummy.h:
Code: 
#include "AudioStream.h"

class AudioEffectDummy : public Audiostream{
public:
AudioEffectDummy() : AudioStream(3, inputQueueArray) ;
virtual void update (void) ;
private:
audio_block_t *inputQueueArray[3] ;
}
as a test-setup i'm running audio from my pc into line-in left, which should be played back on line-out left:

Code: 
#include <Audio.h>
#include <wire.h>
#include <SPI.h>
#include <AudioEffectDummy.h>

AudioInputI2S linein ;
AudioOutputI2S lineout ;
AudioEffectDummy dummy ;

AudioConnection patchCord1(linein, 0, dummy, 0) ;
AudioConnection patchCord2(dummy, 0, lineout, 0) ;

AudioControlSGTL5000 audioShield ;
...

There's absolute silence on the output. As far as I can tell the teensy freezes (as there's no output at all on the serial console if I insert some Serial.prints. there's nothing wrong with the sketch since it's running fine if I exclude the audio-connections).

The shield works fine and is playing audio from example-projects.

I feel like there's a fundamental misunderstanding on my part on how the audio-library works.
 
Your AudioEffectDummy.cpp neglects to check whether inBlock is NULL. You *must* check this. You will sometimes get NULL, especially at startup. You will memory fault the CPU if you use a NULL pointer with transmit().

While I can't see your program's setup() function, another common mistake is forgetting to actually allocate any memory with AudioMemory(). If you've done that, then inBlock will *always* be NULL while the audio library tries to run without any memory to actually do anything.
 
Thank you! With
Code: 
if ( inBlock ) {
transmit(inBlock, 0) ;
}

the sketch is running now, although the line-out remains silent. Here's my setup-function:
Code: 
void setup() {
Serial.begin(9600);
AudioMemory(10);
audioShield.enable();
audioShield.volume(0.7);
audioShield.inputSelect(AUDIO_INPUT_LINEIN);
}

I've double-checked my wiring with the stereo-passthrough example to make sure the line-in is not the problem. What else am I missing?

Appreciate the help!
 
I feel mighty stupid. But I'll gladly share my stupidity. The sketch I'm working on runs on another tty, so copying everything manually to the forums I left out what I commented out over time. The essential thing I missed (while commenting stuff out) was I set the LED on pin 13 high, out of habit (as a "lifesign"). Pin 13 is of course used by the Audio-Shield, thus it didn't work.

My apologies, I'll be more thorough next time. And thanks again still, could've taken me quite some time longer to find this one.
 
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