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Author Topic: Smallest arduino, 24 PWM pins + IIC  (Read 407 times)
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I have a product that I do not care to give away the idea of, but I need to make a custom board that will take my prototype sketch, lose the FTDI chip and other useless stuff, and it must be as small as possible (hopefully close to the size of a dime), plus feature 24 PWM digital i/o + IIC for a single sensor.

Any suggestions, seems there are lots of products out there, and even eagle files that could be modded, I'm hoping someone knows the options better than I do and can narrow the scope for me.
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Does any microcontroller chip support 24 PWM? I think the mega only has 16.
I think you need a 2 chip solution.

What do you need the PWMs to do?
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Something the size of a dime, with 24 PWM pins?  You're out of luck.  For one, there isn't a single AVR that has 24 PWM channels.  The most you're going to get is 15 and that's on the Mega640/1280/2560.  The smallest package that comes in is 9mm x 9mm, either CBGA or QFN.

Perhaps if you explain what you're doing, and why you need 24 PWM pins, others can come up with other suggestions.  Either way, getting something that small with all the pins broken out and you are looking at something that's larger than a dime.
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Maybe a couple of SMD chips on either side of a custom PCB? It's the only way I can imagine getting that many outputs in that small a package.
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hey peter --> that's what I was thinking... the FTDI chip consumes real-estate that's not necessary for the project... I know there's small arduino's with that 9mmx9mm chip, 1 on either side of the board and then stuck in a 3d-printed case could do, I can quickly prototype this and secure funding to get a good run.  It doesn't actually have to be a dime, could be a nickel, but something on that scale I am trying to avoid the finished item being clunky.

I was thinking a 2 chip solution would do.... that FTDI chip is great if you are always popping a usb interface on to fiddle with it, but for set it and forget it tasks I was thinking save a little bit and just use pin holes and a seperate board with the FTDI on it for programming (one time) purposes.

The thing that worried me is the 24 pwm... I don't want four of these things w/ ftdi chips (that'd be a waste of battery).....

Anyways I noticed the following:
Yes, this page: http://www.arduino.cc/playground/Main/GeneralCodeLibrary has links to "SoftPWM" and "PWMAllPins" which are solutions for that.  I haven't used either one myself, so I can't give any idea of what to expect with them, that means I could make 2 of these chips on a single board work right?

So one chip one either side of the board works... or perhaps this (although I'd need two of them):
http://doc.byvac.com/index.php5?title=Product_BV4237.
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The smallest I've seen so far is the Femtoduino at 20.7mm x 15.2mm.  A penny is 19mm.
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Yes, but that's 328 based, only 6 PWM outputs.

Maybe two 2560's in 9mmx9mm leadless packages, with 12 PWMs from each, and ICSP pads for programming.
Doubt that eagle files are availalble for  modding - I don't see a 2560 leadless package in the libraries.

I don't see any leadless parts at mouser, just ball grid array.
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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