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4981  Forum 2005-2010 (read only) / Development / Re: Integrated Arduino  Zigbee with new ATmega128RFA1 on: January 09, 2010, 08:31:33 pm
You might want to wait a bit till you can actually buy such chips.   In an apparently new strategy, Atmel's 12/09 announcement doesn't even include a guess at to availability of the chip (nor could I find anything on their web pages.)  I guess that in theory, this is a less ambitious product than then Xmegas, and could do much better, but...

I'm not sure what the implications of building an RF device from chip level is.   One of the advantages of the "module" approach taken by Zigbee and Bluetooth Arduinos is that Radio certification issues are handed off to someone else...
4982  Forum 2005-2010 (read only) / Development / Re: Crystal question on: April 04, 2010, 03:22:35 pm
The only mystery left is that 22pF is approximately the correct capacitance for these, while 22 uF is impossibly too large a cap.   Did you reverse which ones did and didn't work?
4983  Forum 2005-2010 (read only) / Development / Re: Crystal question on: April 04, 2010, 12:14:09 am
4984  Forum 2005-2010 (read only) / Development / Re: Questions about arduino mega assembly on: March 31, 2010, 09:22:28 pm
The "Fiducial" components are designed to assist Automatic SMT part placement machinery.  Essentially a know shape at a known location so a camera can detect exactly where the board is...
4985  Forum 2005-2010 (read only) / Development / Re: Barebone Arduino as EAGLE file? on: April 01, 2010, 05:38:17 am
I should warn you to check that over for errors; I did it pretty quickly.  None of the other footprints in there have been well inspected or tested, either.  It's sort of a work in progress,
complicated by the subtle differences between clones.
4986  Forum 2005-2010 (read only) / Development / Re: Barebone Arduino as EAGLE file? on: April 01, 2010, 05:08:25 am
4987  Forum 2005-2010 (read only) / Development / Re: Barebone Arduino as EAGLE file? on: April 01, 2010, 02:46:05 am
So, like this?

4988  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 :-)

4989  Forum 2005-2010 (read only) / Development / Re: Hints on switching power regulators on: March 25, 2010, 05:54:46 pm
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!
4990  Forum 2005-2010 (read only) / Development / Re: Arduino on PCB and crystal on: March 17, 2010, 10:58:25 am
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...
4991  Forum 2005-2010 (read only) / Development / Re: Picking a ferrite bead for ENC28J60 on: March 24, 2010, 11:22:34 am
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...
4992  Forum 2005-2010 (read only) / Development / Re: Setting in resin on: March 19, 2010, 06:48:51 pm
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.
4993  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:
4994  Forum 2005-2010 (read only) / Development / Re: opto isotators on: February 26, 2010, 01:50:58 pm
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...
4995  Forum 2005-2010 (read only) / Development / Re: Crystal used in Duemilanove (Datasheet) on: March 09, 2010, 04:48:10 pm
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...
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