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Topic: Another DIY Arduino with PCB (Read 3 times) previous topic - next topic

Paulware

Apr 13, 2012, 06:24 am Last Edit: Jun 01, 2012, 03:48 am by Paulware Reason: 1
 I'd like to start yet another rehash of DIY Arduino.  This time with a pcb that is within 5cmx5cm size so that iteadstudio will build it for $1.40 in packs of 10.

 The actual shield size is a fraction of an inch bigger so female headers bend just slightly.

 You will need an atmega328 or atmega168 with bootloader flashed, and a CP2102 which is a $3.00 (ebay) usb to serial converter, which has been slightly modified to connect dtr to reset line.

 Actual cost is about $7.00:  pcb: $1.4, atmega328: $3.30, other parts about $2.00

 Here is a video
  http://www.youtube.com/watch?v=5w_5BnfnPGQ

   Schematic, Board and Gerber files: http://atmega.site40.net/default.php?bookmark=ArduinoDIY

 It also has optional breakouts for an nrf24l01 so that it can be used for home automation

westfw

Pretty nice!

Your projects seem to consistently use those 2-termial ceramic resonators without the usual caps to ground.  Does that seem to work with reasonable accuracy?

100Grand

WoW!!! Thanks aloott!!!!!!! That really helped!

Paulware

Hi westfw,

  I picked to the ceramic clock mostly for price.  I didn't realize there was a potential issue with not having a ground pin.   

  I would have to compare to a build with a grounded clock to see if it behaved differently. 

  I do know that driving some dc motors, depending on load and weak batteries the system can occasionally lock up.  I got around this issue by using pwm outputs to hbridge and lowering the duty cycle.

  You could take my schematic and change the clock to a 3 pin clock, or I could post one for you if you are not familiar with Eagle.

  Thanks for the coment.
Paul

SirNickity

If it's a design you're giving out, or especially selling pre-manned boards, I would vote for having that ground pin hole.  It may work without, but you're probably out of spec on the ideal load capacitance of your oscillator.  And after all, it's harmless if you don't use it yourself.

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