Selection of a microcontroller for Childs Toy...

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Hi,

We are designing a simple childs toy with the following features:

* 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


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

Quoted text here. Click to load it

'real' DACs will be expensive and rarely found on low-cost micros  - you should
look at using PWM
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,

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


Quoted text here. Click to load it

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

Quoted text here. Click to load it
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.

Quoted text here. Click to load it
64MHz clock. With
Quoted text here. Click to load it
Sucks a bit of power
Quoted text here. Click to load it


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

Quoted text here. Click to load it
look at using PWM
Quoted text here. Click to load it
64MHz clock. With
Quoted text here. Click to load it
Sucks a bit of power
Quoted text here. Click to load it


How about RC-2 encoding ? There is a nice article in Circuit Cellar
#180 about this using an AT89C4051 MCU.

Regards
  Anton Erasmus

Re: Selection of a microcontroller for Childs Toy...
Take a look at TIs 430 family.  Low power less than $1 in low qty.
A/D.

Look at this months Circuit Cellar for a novel speech design for a
micro.

george


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

Quoted text here. Click to load it


Hi Tim,

If you can elaborate on what "2 minutes of pre-programmed sounds" means. I
really think this is key to what hardware you should select. Are they tones?
Is it speech or complex sounds? To pre-program a simple tone can almost be
infinitely smaller (memory/complexity wise) than other type sounds.

Thomas



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

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)

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.

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

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


Re: Selection of a microcontroller for Childs Toy...
Quoted text here. Click to load it

  Look at the C8051F330P, comes in DIP20, and has a 10 bit DAC, and 25
MIPS core. It also has on chip debug.
  For the sound(s) you'll be best with separate SPI Flash, or DataFlash
  storage - consider using more than one, and probably plugable, if you
want to simplify loading them.
  Look at some of the storage-cards for cameras, etc.
  Your toy is then a relatively simple tune/melody chooser/player.
  Another PC centric system is needed to create the sound files.
-jg


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


Quoted text here. Click to load it

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

Quoted text here. Click to load it

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.

Quoted text here. Click to load it

A serial data flash should be more than enough.

Quoted text here. Click to load it

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

Quoted text here. Click to load it


Re: Selection of a microcontroller for Childs Toy...
Quoted text here. Click to load it

How about this:
CPU - PIC16F73 - has more than enough inputs for the buttons and two PWM
outputs that you can use for your audio playback; one for the voice, one for
the melody. A simple 3rd order or 4th order RC lowpass filter is all that's
required on the output to get decent sound quality. Cost $3.50 in quantities
of 250 from Digikey.

memory - M25P20 - serial flash memory 256KB which will hold 32 seconds of
audio at an 8 KHz sampling rate. Cost $1.21 in quantities of 250 from Digikey.

audio amplifier - LM386 assuming you have more than +4.0 VDC to work with.
Cost $0.27 in quantities of 250 from Digikey.

Total cost $4.98 and it fits all your requirements except for onboard EEPROM
but it sounds like external FLASH will work just as well since you didn't
mention any physical size restrictions.

--Tom.

Re: Selection of a microcontroller for Childs Toy...
Thanks for your advice Tom...

It looks functionally exactly what I need & at the price pt I need...

I am going to look into these furthur...

-Tim


OT:

Quoted text here. Click to load it
Tim,

May I ask you point me to texts describing the Sound Blaster itself,
what functions it offers like FM systhesis, etc. and to a programming
manual.

I would like to link my theoretical knowledge of Digital Signal
Processing to something physical like a sound card.


Thank you very much in advance.
--
Jean Castonguay
lectrocommande Pascal


Re: OT:

Quoted text here. Click to load it

Years ago I bought a Software Developer's kit for an early Sound Blaster.
Contact Creative Labs.


Bob


Re: OT:
Hi Jean,

My apologies for taking so long to get back to you. I have been out of
town...

There have been many versions of the soundblaster over the years. The
early ones I believe had fm synthesis to be compatible with the "Adlib"
family of boards. To that they added 1 channel of 8 bit wave file
playback. Eventually, the "soundblaster 16" added 16 bit playback and
more channels.

I used to have the sound blaster development kit but I do not know
where to find it any more...

You are correct, this is a great place to apply theoretical knowledge
of Digital Signal Processing
Here is a link with a good place to start...

http://www.synchrondata.com/pheaven2/www/area24.htm

The files are actually located on Programmers Heaven Website.

Hope this helps,

-Tim


Re: Selection of a microcontroller for Childs Toy...
Winbond is an option, but Sonix is probably the best.
www.sonix.com.tw.  They work with Kodec, so you could contact them
also, I think it's Kodec.com.  Also, Alpha has some cool stuff
ealpha.com.tw.

I worked for Hasbro so I know these quite well

snipped-for-privacy@gmail.com wrote:
Quoted text here. Click to load it


Site Timeline