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Author Topic: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?  (Read 2507 times)

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Offline VegaObscuraTopic starter

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I'm about to try my hand at making the $50 robot, but the part number for the Atmega8 AVR listed is out of stock at digi-key.  That part number was: ATMEGA8-16PU-ND

I want to know if this would work in place of it with no modification to the instructions on how to make the bot:     ATMEGA88PA-PU-ND

Everything I can find on their specs seems to be identical except the speed, whereas the original one listed was 16mhz and the one I'm hoping will work in place of it is 20mhz.

Offline rbtying

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #1 on: October 03, 2010, 11:17:16 PM »
It's a drop-in replacement, I believe, but if you're going to go and upgrade, why not get an ATMega328 (more memory), which supports webbotlib for the future?

Offline VegaObscuraTopic starter

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #2 on: October 03, 2010, 11:33:20 PM »
As long as it will work 100% with the instructions in the $50 bot tutorial with no modifications, give me the part number and I will certainly consider it.

Offline greywanderer012345

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #3 on: October 04, 2010, 07:14:38 AM »
ATMEGA328-PU-ND

But I'm using ATMEGA168A-PU-ND

Anyone know the difference between this and ATMEGA168-20PU-ND. Same specs, $1.10 price increase...?

Offline rbtying

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #4 on: October 04, 2010, 08:20:43 AM »
It has double the flash memory (program space), so you can fit a bigger program on there.  Main advantage is the ability to use Webbotlib, which as far as I can remember no longer supports ATMega168 or lesser memory.  I'm not too sure if it'll need any modifications, but if it does, it'll be in the setup section - no hardware changes, as its a pin-for-pin replacement, but there may be some avrdude settings you'd have to change. 

Offline madsci1016

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #5 on: October 04, 2010, 08:46:10 AM »
The Atmega 8 series work like this:

Atmega8            8kB of memory
Atmega(16)8      16kB of memory
Atmega(32)8      32kB of memory

It's all the same MCU core, just more or less memory, as seen by the 'model' number. for the extra buck or two, i'd always say get the 328.

I do not know what the difference is in the P or V models. We usually use P around here.

Offline VegaObscuraTopic starter

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #6 on: October 04, 2010, 09:28:23 PM »
Unfortunately, digikey is out of ATMEGA328-PU-ND AND ATMEGA168A-PU-ND.

Offline vinito

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #7 on: October 04, 2010, 10:16:50 PM »
But they're such a small little thing, they should be able to whip our a hundred thousand in about a half hour.
I tell ya. If I was in charge...

But seriously, there are many more sources other than digikey. Price likely varies. Some have the Arduino bootloader written to them, but just re-program it if you don't want it.

http://www.sparkfun.com/commerce/product_info.php?products_id=9061
http://www.junetrading.com/product_info.php?products_id=5589
http://www.moderndevice.com/products/arduino-programmed-atmega328-chips

Maybe a couple bucks more, maybe not. Probably several other sources out there too of course.

Offline Metal Slug 2

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #8 on: October 05, 2010, 12:19:15 AM »
Regarding the "P" or "A" numbers on an Atmega chip, an "A" means the chip uses slightly less power...as in a difference from maybe 11 mA for an original atmega8, to 6 mA on an atmega8A.

heres more info if your interested:

atmega8-atmega8A: http://www.atmel.com/dyn/resources/prod_documents/AVR523.pdf
atmega168-atmega168A: http://www.atmel.com/dyn/resources/prod_documents/doc8166.pdf
atmega168-atmega168P: http://www.atmel.com/dyn/resources/prod_documents/doc8035.pdf

Offline greywanderer012345

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #9 on: October 06, 2010, 12:28:30 AM »
Regarding the "P" or "A" numbers on an Atmega chip, an "A" means the chip uses slightly less power...as in a difference from maybe 11 mA for an original atmega8, to 6 mA on an atmega8A.

heres more info if your interested:

atmega8-atmega8A: http://www.atmel.com/dyn/resources/prod_documents/AVR523.pdf
atmega168-atmega168A: http://www.atmel.com/dyn/resources/prod_documents/doc8166.pdf
atmega168-atmega168P: http://www.atmel.com/dyn/resources/prod_documents/doc8035.pdf


Wow, thanks! I've been trying to figure that out for a while now. I couldn't even find anything in the documentation. Good info.

Offline cyberfish

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Re: $50 Robot - Digikey out of Atmega8 listed - Possible alternatives?
« Reply #10 on: October 06, 2010, 01:47:50 AM »
As for V, it means the part is rated for lower voltage operation at lower clock speed. At 5V they are equal.

 


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