Let's Make Robots!

How hard would it be to build an Arduino?

I recently assembled the Really Bare Bones Board, pictured below.  It's an Arduino clone in a smaller and more affordable package.

RBBBrevB_front_800.jpg

The board is $12, which is a great deal.  But I want to lower my costs as much as possible.  During a 3-hour car trip today my mind was racing with ideas for potential robots, and I began realizing that for the projects I want to do I'm going to need multiple embedded microcontrollers.  What's more, each microcontroller board will need different appendages ... some with their own voltage regulation, others with motor controllers, some won't need analog input, and some will need LED's while others won't.  I like the idea of having each board with its own specific functions and abilities, rather than wasting money on an all-around package with some things I don't need and lacking something I might need.

Anyway ... the point is that it might make more sense for me to buy ATMega168's with the Arduino bootlegger and make my own microcontrollers.  Problem is ... I'm not entirely sure how to do that ... so maybe you guys can help me out? 

Ok so here's what I know I need: The ATMega168 needs a steady supply of 5 volts.  That's easy enough to pull off with a voltage regulator and a couple of capacitors. Next up is the resonator ... which I have a fairly good understanding of.  I know what pins to connect to, anyway, which I guess is all that matters.  Next up is a test LED, which of course is super easy.  And lastly the reset button, which I'm sure I can figure out.

Other than that, though, I don't know what the microcontroller needs to do its thing.  Looking at the RBBB, I don't know what all that stuff does.  What are the two capacitors for, for example?  There are two 47uF capacitors and I don't know what they do.  Does it allow for analog input via a resistor-capacitor circuit?  What about that diode there?  Is that for blowback voltage?  How about those resistors?  And lastly ... I'm very embarrassed to say I don't even know what the blue thingies are.  I'm assuming they're capacitors, but I could be wrong.

Thanks for helping out a beginner!  Sorry for the big blocks of text ... there's just so much I still don't know!!

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ya know, I saw that table, but it seemed low for a uproc. Of course looking at the other tables, it shows the current consumption for the proc in "active mode" at 16 mhz to be around 10ma(p317).

Anyway,  this link has some data on running off of a battery and doing some simple tasks.

That guy on the link did some very extensive testing.

One micro I'd been told was very easy on power was the Texas Instruments MSP430 series, had some demo running forever off a coin cell, something about using microamps rather than milliamps. Thay have a USB try tool for $20. And Atmel has their AVR Butterfly (a very fun toy) that is also powered by a coin cell, runs a Mega169 I think, and has a lot of cute apps running on it for about $20 too. 

Here is another writeup about making a standalone Arduino. 

 

http://art364.pbwiki.com/Standalone+Arduino

 

I'm wondering if the resonator would work more easily than the crystal. I tried buildng the setup mentioned, though with caps instead of without, and wasn't able to get things to work when usng a crystal. once soldered though, the crystal worked fine. I tried this on two different breadboards with two different ardys and 2 different crystals...(plus the 22pf caps).

 

Because the conductors are relatively close on a solderless breadboard, they tend to act a little like capacitors. Higher frequency (MHz) stuff tends to stop working on these, but can do better on a soldered breadboard.
Ok so then the most affordable option is probably to just focus on the resonator and a steady +5v, and then program the Mega168 in a real Arduino.
I have had good luck with Fundamental Logic. Their prices and delivery are excellent.
 
 
Myc 
Thanks ... looks like that's the most affordable option with shipping.  Added to the list.

Probably just smoothing capacitors of some kind.

All you really need is the chip and bootloader, resonator or crystal, and a steady 5v. A reset switch and pullup resistor are good too.

Heres an arduino on a breadboard.

 

There is a website around where they show you how to use an arduino to write the bootloader to other atmega168s so you don`t even need a programmer.

Ok so voodoobot pretty much answered all my questions in the shoutbox, but I'll leave this topic here in case anyone else has something to add.

Meanwhile, I (and voodoo) am seeking out a way to make an absolute bare minimum Arduino for under 5 dollars.  Not sure if it can be done, but I've started researching ATMega168-20PU prices, since it's the most expensive component.  I'll post my findings here as I continue to search.

$3.30 - http://www.onlinecomponents.com/product/3588566/ - A great deal.  Free ground shipping, too.  Unfortunately ... $35 minimum, so only worth it if you order a bunch of other stuff from them (or 12 ATMega's).  Maybe worth a one-time investment to have a whole bunch of chips on hand?

$3.35 - http://www.sureelectronics.net/goods.php?id=717 - Shipping to California calculated at $4.18.

$3.68 - http://store.fundamentallogic.com/ecom/index.php?main_page=product_info&cPath=4_7&products_id=16&zenid=94c85636ee14e7f5cf827a12183e7458 - Calculated shipping to California was $2.27. 

$3.90 - http://www.seeedstudio.com/depot/atmega16820pu-28pin-dip-w-arduino-bootloader-p-55.html - My shipping (to California) was calculated at $2.58 for one chip.  

$4.11 - http://parts.digikey.com/1/parts/552130-ic-avr-mcu-16k-20mhz-28dip-atmega168-20pu.html - Couldn't see shipping costs without entering my payment info. 

$4.95 - http://www.sparkfun.com/commerce/product_info.php?products_id=8846 - If you're already ordering from SparkFun, it'll be more cost effective to throw this in your basket and pay a bit more for the product itself.  Plus, you don't have to worry about burning the Arduino bootlegger.  Not to mention ... who doesn't love SparkFun? 

$3.23 - https://emwcs.avnet.com/webapp/wcs/stores/servlet/Product_-1_500201_500201_part_0_3591975 - Don't be fooled by the low price ... shipping is $8.00.