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4966  Forum 2005-2010 (read only) / Development / Re: Barebone Arduino as EAGLE file? on: April 01, 2010, 05:08:25 am
http://homepage.mac.com/westfw/.cv/westfw/Sites/.Public/arduino-footprints.lbr-zip.zip
4967  Forum 2005-2010 (read only) / Development / Re: Barebone Arduino as EAGLE file? on: April 01, 2010, 02:46:05 am
So, like this?

4968  Forum 2005-2010 (read only) / Development / Re: Barebone Arduino as EAGLE file? on: March 31, 2010, 05:45:54 pm
You mean a library file of just the chip itself, with appropriate pins labeled D0..13 and A0..5 ?

Interesting idea...  (a good project to practice your library editing skills :-)

4969  Forum 2005-2010 (read only) / Development / Re: Hints on switching power regulators on: March 25, 2010, 05:54:46 pm
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I got fed up with Nimh cells, they have this delightful habit of self discharging
There is new technology ("low self discharge" or "pre-charged") that minimizes this, typified by Sanyo "eneloop" series.  They seem to work quite well!
4970  Forum 2005-2010 (read only) / Development / Re: Arduino on PCB and crystal on: March 17, 2010, 10:58:25 am
Code:
Why isn't writting the bootloader as simple as putting the chip into arduino board and hitting Burn bootloader?
It IS, if you're using one of the supported standard AVR ISP programmers connected to the ISP header of the chip.

I think you will have to disable auto-reset on the arduino being used as a programmer (call it PGMR) in order to program another Arduino (call it TARGET.)  Otherwise, running avrdude will reset PGMR and it will end up in the PGMR bootloader, instead of the sketch talking to TARGET.  The instructable you link to uses a BBB, and is probably from the time period before the BBB had auto-reset...
4971  Forum 2005-2010 (read only) / Development / Re: Picking a ferrite bead for ENC28J60 on: March 24, 2010, 11:22:34 am
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I'm working on an Arduino clone that will have an embedded Ethernet interface. I'm basing it on the ENC28J60 chip
Me too, sort of.  I don't like not having a modifiable TCP/IP stack.  In a sense the Wiznet is the ultimate in "closed source."  But the amount of code inside the Wiznet is probably larger than will even FIT in an Arduino, so the tradeoffs are interesting...

Have you thought about ENC28J60--AVR--AVR (two avrs), with the first running some network code, and the second running the user's sketch?  (essentially, make a user-programmable equiv of the Wiznet using ENC and an extra AVR.)  In theory, an added advantage could be upload-over-ethernet via a 2nd IP address or special port, connected to the Arduino-AVR serial port...
4972  Forum 2005-2010 (read only) / Development / Re: Setting in resin on: March 19, 2010, 06:48:51 pm
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You want to use a resin that's made FOR display.  Resins made as glue or for surfboards, etc will yellow with age
Resins not specifically made to be clear are likely to start off with some color, as well as a surface that is neither hard nor glossy (This is a "feature", since it helps the next layer stick better.)  Many epoxies are rather brownish, for example.

If you have a TAP Plastics store near you, they'll typically have several different resins for sale, and the stores will have SAMPLES of what the cured resins look like.
4973  Forum 2005-2010 (read only) / Development / Re: opto isotators on: February 26, 2010, 08:12:05 pm
I dunno.  You seem to be using "optoisolator"  interchangeably with "solid state relay."  The usual opto-isolator has a relatively low-power transistor on its output side, so connecting it to control arbitrary loads is relatively complex.  Solid state relays have their own sets of issues (many are good only for AC, for example.)
Optoisolators are also slow, large, not bi-directional, not tri-state, and expensive by arduino standards, and frequently not relevant to the sorts of projects people use Arduino for.  I spent a bit of time once looking for a simple circuit or chip to upgrade the current output of an Arduino (or other microcontroller) pin to 200mA or so, without losing the other features of the Arduino pins.  I didn't find anything, and I wasn't even looking for isolation.  Try to make things bulletproof and very general, and you rapidly arrive at your $600 sorts of solution :-(

There was this opto-isolated H-bridge posted recently:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1265418204
4974  Forum 2005-2010 (read only) / Development / Re: opto isotators on: February 26, 2010, 01:50:58 pm
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Great product but it still cant handle the current needed to power the kind of steppers
I thought you were talking about isolation?  Motor drivers are an entirely separate issue (and one with many more variables, as you note)!  If you're asking for a list/matrix of opto-isolated motor drivers that are compatible with arduino, that's yet a third question...
4975  Forum 2005-2010 (read only) / Development / Re: Crystal used in Duemilanove (Datasheet) on: March 09, 2010, 04:48:10 pm
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You can not get a +/- 100ppm crystal to +/- 10ppm by means of selection.
You could replace the crystal with a +/-10ppm one; they seem to be available...  though it's still probably a silly idea to try to synchronize multiple systems by trying to make sure they all run at the same clock rate...
4976  Forum 2005-2010 (read only) / Development / Re: Crystal used in Duemilanove (Datasheet) on: March 05, 2010, 06:49:27 pm
Good question.  I don't have a lot of faith that the caps associated with the arduino are properly sized; there's a sort of "standard" to plunk down a crystal with a couple of 18 or 22 pF caps, but apparently if you want to do it RIGHT, it's a bit more complicated than that (and you'd need the crystal data sheet to start with.)  OTOH, I've never much cared about higher accuracy than needed to make serial com work, so I haven't been overly motivated to track anything down...

In general, if you want to synchronize multiple CPUs, you have to come up with a solution other than giving them all infinitely-accurate oscillators.

4977  Forum 2005-2010 (read only) / Development / Re: Seriously what is Atmel's problem??? on: March 11, 2010, 11:46:13 am
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What's the difference between the two? What does the A in PA stand for?
Don't know.  "A" is a frequent "sequence number" sort of thing tacked on to a chip number when minor changes are made due to (for example) a new, smaller, chip geometry and size.  Some of the Microchip pics are up to "C", I think.  Frequently there are supposed to not be any customer-visible changes.  OTOH, sometimes there are.  I haven't looked carefully at what Atmel claims...
4978  Forum 2005-2010 (read only) / Development / Re: Seriously what is Atmel's problem??? on: March 11, 2010, 05:40:07 am
The 168 is apparently being phased out and replaced by the 168PA; I suspect the transition is messing with things.  Mouser has some of those:
 http://www.mouser.com/ProductDetail/Atmel/ATMEGA168PA-MU/?qs=sGAEpiMZZMvu0Nwh4cA1wdLkbYSnKaVLTXuBDUZ03ng%3d
4979  Forum 2005-2010 (read only) / Development / Re: power regulator for Xbee? on: March 10, 2010, 06:11:05 pm
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its max output current is 444mA. Do you think it will be enough
"444mA"?!  that's a lot of significant digits for a power supply!  In any case, it sounds OK.  The Arduino itself is well under 100mA, and the max232 is "small" (~10mA, probably depending on loading of the signal lines.)  So it sounds pretty much "just right."
4980  Forum 2005-2010 (read only) / Development / Re: power regulator for Xbee? on: March 10, 2010, 05:22:30 am
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I have read everywhere that I need a power regulator to supply the Xbee chip with 3.3Volts... But why can´t I simply use the Arduino 3.3V pin?
Unfortunately, typical current consumption of the Xbee modules is over 200mA when transmitting, an the Arduino 3.3V pin only provides about 50mA.

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I have already seen several datasheets and I noticed that I normally need a number of capacitors around the power regulator... I am quite a newbie in electronics and I never liked working with capacitors, can I just assume that the circuit that manufacturers provide will work with my Xbee
Yes.  Your requirements are pretty simple.  It should accept 5V as an input (or 6-20V on Vin?) and output 3.3V at up to 400mA or so (to be safe.)  A lot of people are using (and apparently happy with) the LD1117 type regulators here.
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