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How to implement audio features for a toy

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I'd like to make toy like a busy-box for my daughter using my Stellaris LaunchPad.  I know how to implement the basic switch inputs and LED outputs.  But I'd like to add some audio features and I don't know how to implement those.


I'd like to:

  • Record and play back several seconds of voice
  • Play sound effects and short musical samples stored in nonvolatile memory


My questions are:

  1. What hardware components should I use to record and playback basic quality audio?  A mic and speaker seem obvious, and probably a ADC and DAC, but what else is required?
  2. Is there a booster pack that I can use?
  3. In what format should the audio samples be stored in memory?
  4. Is there some software library or codec I should use or can it be simpler than that?

Any information or links are appreciated.  Thanks.


 -- Kevin

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@@kkrambo You might want to look into an ISD4003 or something similar with less pins and require less external components, and many of the other chips in that category will be a bit cheaper also, though many will probably have lower sound quality which is probably fine. Just to get an idea of how it fits in, the ISD4003 can record and play 4 minutes of audio and takes care of most of the work, here is an example of it being used as a voice shield for an arduino including some of its benefits, the parts a kit comes with, how to program it and load audio samples, and a link to a coinbot that uses it to play random sounds. These types of chips more or less do all of the work for you which might also take all of the fun out of it. Many of those types of chips come in dip packages so it should be easy to prototype and breadboard. If you use the shield as a guide, you'll have to change the relevant stuff to work with your stellaris such as verifying the voltages, pins, and changing the sketch to work with Energia if you want.


I haven't done direct sampling of audio myself, but if you do want to skip using a dedicated IC and instead use the adc and a mic, you might want to consider storing those samples to a SD card, just make sure the sd library works well for the throughput.

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Thanks for the ideas.  I ordered an ISD4003 ChipCorder along with an LM386 audio amp and some other parts.  Those recordable greeting card modules on ebay are cool and cheap too -- I may get some of those for another project.


In case anyone else is interested, here are a few other related links I found:


This article is a walk through of how a commercial toy with voice is developed.  They use a custom WinBond part, which I believe is like the ISD4003 Chip Corder.


This guy uses the ChipCorder parts to incorporate sound into his Halloween projects.


This article discusses other audio techniques besides the ISD4003 ChipCorder and has lots of further links.

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