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



Mike Harrison wrote:
> On 29 Jun 2005 21:15:00 -0700, hypnoplay@xxxxxxxxx wrote:
>
> >Hi,
> >
> >We are designing a simple childs toy with the following features:
> >

Must be school project time. (same question by a different poster).

> >* Must Respond to up to 5 buttons
> >* Output up to 2 minutes of preprogrammed sounds through a speaker
> >* Must be programmable to respond in different ways according to the
> >order of the button pressed
> >
> >It is preferred that the microcontroller contain an 8 - 12 bit onboard
> >DAC, EEPROM programability, low voltage consumption...
> >
> >Optional features would include melody output (To play music while
> >sound is playing).
> >
> >I have investigated the Winbond Powerspeech series. It seemed perfect
> >at first glance, however it is not offered with EEPROM. We plan on
> >producing these in bunches of 100-500 thus necessitating the EEPROM.
> >
> >Any suggestions would be appreciated.
> >
> >Thanks,
> >
> >Tim
>
> 'real' DACs will be expensive and rarely found on low-cost micros - you should look at using PWM

It's not so much a cost issue. Placing DAC on micro is not expensive,
but difficult to isolate the noise problems. For PCB, you should
provide separate power and ground as much as possible. It would be
more difficult to do so, if the DACs are on the micro.

You can easily build a flash DAC with an op-amp and 10 to 15 resistors.
You wouldn't get commerical hi-fi quality, but good enough to pass the
course.

> etc. techniques.
> The Atmel ATTiny26 has a PLL peripheral clock mode that will do PWM with a 64MHz clock. With
> suitable software you should be able to get a decent audio signal using this. Sucks a bit of power
> in this mode but if you're driving a speaker this will not be too significant,

.

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