PicoMite: can we explain/fix "ticking" when using PLAY SOUND


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thwill

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Joined: 16/09/2019
Location: United Kingdom
Posts: 3888
Posted: 10:56am 17 Mar 2023      

  Mixtel90 said  Make sure that any PAM8403 modules (or any digital amplifiers for that matter) that you are using have output inductors on them.


Can you point me at a picture of a "good" module, because either I'm rolling a 1 on my "recognise surface mount inductor" check, or none of them have one .

  Quote  I'm not saying that this is the case here, but it's something to bear in mind.


Given that the PicoGAME VGA 1.4 has the same click (though not "amplified" to the same extent) I don't think we can entirely blame PAM. Does the PicoGAME VGA have the power filter on the SD card that Peter mentioned above ?

I haven't had a chance to give the hardware another poke yet (i.e. try without the LCD/SD module attached) but I am still suspicious that this is specifically a PLAY SOUND issue, my lo-fi ears can't hear the same problem with PLAY WAV.

Peter, I've only executed it in my head but looking at the implementation of PLAY SOUND (Audio.c#1271-1296) it appears you always set sound_mode_{left|right}[channel] to nulltable first even if it was, for example, SineTable before and will be SineTable after the call. Is this code run in parallel with the actual playing ? in which case could their be a race-condition where you end up briefly "playing from the nulltable" and hence a click ? Or am I making s**t up; this is too close to the hardware for me to have any expertise.

Best wishes,

Tom
Edited 2023-03-17 21:09 by thwill