Re: Selection of a microcontroller for Childs Toy...



hypnoplay@xxxxxxxxx wrote:
> Thanks Mike, george, linnix,
>
> I have checked out the links & will investigate them furthur. Actually
> my background is in programming so I kind of feel like a fish out of
> water on this subject. (Although it may sound like a school project,
> its actually for end consumers)
>
> I am familiar with PWM techniques in general. (it sounds like this is
> the way to go)

PWM is fine for simple tones, but it would sound flat. Namely,
difficult to product quality sound.

>
> Once I land on a chipset & receive a development kit I think I will
> feel more comfortable from there.
>
> Let me elaborate a little more on the project:
>
> * The toy is meant to play musical songs with a digital file running
> simaltaneously in the background.
> * Fairly high quality sounds are required (for a toy) minimum 8khz 8bit
> mono.
> * Melodies must play for 2 to 5 minutes in the foreground while digital
> sounds can repeat in the background(at least 20 seconds)
> * oboard EEPROM for code as well as data is preferred
> * However, this is meant to be an upscale item, so a chip/chipset
> costing $5 would not be out of the question. (Quality is mandatory)

How about space requirement? If you need small space, get an I2S DAC
(a few dollars). Otherwise, building the flash DAC is cheaper and
easier to work with, since you would likely need to build the PCB
anyway. PCB (approx. 2 sq. in) costs 0.25, op-amp costs 0.10 and
resistors costs 0.01 each.

You can use a simple AVR/PIC/etc. to drive the DAC.

>
> I am figuring on at least 20 secs of digital sounds (8khz 8bit mono)
> without compression off the top of my head probably comes to ~150k.
> Plus the 2 minutes of melodies which shouldn't take nearly that much.

A serial data flash should be more than enough.

>
> At this much memory, any thoughts on hardware decompression, software
> decompression or going without decompression?
>

Compression is probably not needed. You are generating tones from data
anyway.

> I do have some background in this field, as I wrote a custom Sound
> Blaster Driver years ago. I would prefer a chip capable of 2 seperate
> channels(mono) of audio as opposed to mixing the channels into one.
>
> I really appreciate the help in making this selection, I feel a little
> overwhelmed with the choices...
>
> -Tim

.

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