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Full Discussion: C++, std:ofstream, and controlling an amplifiers mute function
Top Forums Programming C++, std:ofstream, and controlling an amplifiers mute function Post 303029758 by Circuits on Thursday 31st of January 2019 03:18:29 PM
Old 01-31-2019
C++, std:ofstream, and controlling an amplifiers mute function
Recently, I updated the unit I am running applications on with a new CODEC and amplifier; the older parts are EOL. There was a bug with the old setup. For some reason, even when a tone was not being generated, you could hear a noise emanating from the speaker when the LCD brightness was on a higher setting.


In order to counteract that problem the Amplifiers mute function (standby for old amp) was toggled on and off before and after a tone was produced:


Code:
const char *const amplifierGPIO = "/sys/class/gpio/gpio107/value";

    void amplifierOn()
    {
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "1";
        amp.close();
      }
    }

    void amplifierOff()
    {
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "0";
        amp.close();
      }
     }

The problem is that now in order to get the same functionality to work with the new amplifier I have to surround the ofstream in sleep statments:


Code:
const char *const amplifierGPIO = "/sys/class/gpio/gpio107/value";

    void amplifierOn()
    {
      sleep(1);
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "1";
        amp.close();
      }
      sleep(1);
    }

    void amplifierOff()
    {
      sleep(1):
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "0";
        amp.close();
      }
      sleep(1);
     }

1) Any ideas about why this might be the case? I do not believe it's the mute function on the amplifier itself because outside of the application that uses this ofstream (inside the boot loader) I can play a song and toggle it on and off with the mute function, with no delay needed.


2) Is there another way (other than ofstream) of toggling the GPIO pin 107 from within my application?
 

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LEARN ABOUT DEBIAN

tonegen

TONEGEN(1)						    Voicetronix Telephony Tools 						TONEGEN(1)

NAME

       tonegen - Test the Voicetronix programmable tone generator

SYNOPSIS

       tonegen [options]

DESCRIPTION

       The tonegen utility uses the programmable tone generator to send tones to some port.

OPTIONS

       The following options are available:

       --card number
	      Explicitly select the card to test.  Default is card 0.

       --port number
	      Explicitly select the port to test. Default is port 0 of the card being tested.

       --toneid num
	      Play  a  locale  specific  predefined  tone,  where 0 <= num < VPB_TONE_ID_MAX.  The locale is decided according to the value of the
	      VPB_COUNTRY environment variable.

       --tone n freq mag
	      Set a single component for a user defined tone.  This option may be used more than once with different values of n to set the compo-
	      nents of a multi-frequency tone.	Legal values for the other parameters are 0 < freq <= 4000 (Hz), and -inf < mag < 0.0 (dB).

       --ontime ms
	      The number of milliseconds that a user defined tone should be on for.

       --offtime ms
	      The number of milliseconds that a user defined tone should be off for.

       --dial digits
	      Generates a dial string using the specified dtmf digits.

       --sync Play tones using the synchronous api functions.  The default is to use the async api.

       --loop Loop cadenced tones continuously.  Has no effect if a continuous tone has been specified.

       --recgain db
	      Set software record gain in dB.  Default is 0.0

       --rec file
	      Record audio to a file while playing.

       --contest
	      Do  not  wait  for a tone to complete before starting the next one.  This can be useful for stress testing the coherency of the tone
	      generator.

       --help, -?
	      Show summary of these options.

AUTHOR

       Ron Lee, Voicetronix <support@voicetronix.com.au>

       This manual page was written by Ron <ron@debian.org>, for the Debian project (but may be used by others).

VPB driver package						   Feb 18, 2007 							TONEGEN(1)
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