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5161  Forum 2005-2010 (read only) / Development / Re: Good Wire to PCB Option? on: March 25, 2009, 08:18:20 pm
See also: http://www.ladyada.net/make/boarduino/ideas.html which includes some part numbers...

The big decision is how small your want the connectors.  getting them on 0.1 inch centers is possible, but seems to be pricier than the "normal" size of about twice that.
5162  Forum 2005-2010 (read only) / Development / Re: Shield-Duino on: March 25, 2009, 08:21:06 pm
One problem is that the Arduino form-factor is pretty limited on the amount of space you have at the edges for putting connectors, especially if you're trying not to interfere with the "tall" components on the main Arduino board...
5163  Forum 2005-2010 (read only) / Development / Re: Shield-Duino on: March 24, 2009, 03:59:40 pm
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I see no value in all these shields that "bring up" the ICSP headers from the original board
The original (and followon) Zigbee shields use the ICSP header for power (grr.)  Several shields (mostly proto shields?) that pre-date diecimila  use it to extend "RESET" of the arduino to the shield (button, or for bootload-via-shield capability.)  I don't like it either :-(
5164  Forum 2005-2010 (read only) / Development / Re: Shield-Duino on: March 24, 2009, 10:29:24 am
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this could be "multi" core, if designed correctly, right?
Yes, assuming SPI or some multi-drop serial protocol.  But mostly it probably equates to an easy way to make a stock arduino into a "dual core" arduino.  

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What about having two set of headers?
So that one could stack an additional shield on top of shielduino.
Yes, that's the plan.  The original arduino shield connectors would stack, and the equivalent connections form the "coprocessor" would go somewhere else.  (next to the proto area in the pcb pictured.)  That lets you add additional shields to the original arduino, but doesn't let you add shields to coprocessor.
5165  Forum 2005-2010 (read only) / Development / Re: Shield-Duino on: March 24, 2009, 02:41:37 am
Works fine if your logged into picasaweb as me :-)
Fixed?  maybe?  It's just a rough draft picture anyway...
5166  Forum 2005-2010 (read only) / Development / Shield-Duino on: March 24, 2009, 12:08:17 am
There are a lot of things that the ATmega CPU on an arduino could be programmed to do, relatively easily, that are a bit ... exclusive ... of having the arduino do other (normal) things.  They might have tight timing requirements, use up large amounts of the available CPU time, use timers in ways that conflict with analogWrite(), and so on.  Multiple servo motors, multiple serial ports, and large display (video or LED) refresh are typical examples.  Yet the Arduino environment is known and understood, and it would seem a shame to require a special purpose shield to do the same thing that an arduino could do.

So... What do you think about putting the basic Arduino core (16MHz Atmega168/etc) ON A SHIELD.  Essentially a "slave" arduino, or an arduino "co-processor" based on Arduino...

It would communicate with the main arduino by serial or SPI.  It could be programmed by running a special "relay" sketch on the main arduino, or by ICSP, or by unplugging the 168 and plugging it into a real arduino.  It would tap power from the main board, as per most shields, and replace the power and usb areas of the normal arduino with a prototyping area for additional circuitry.  The PCB could double as a "reduced" arduino "runtime board." Ardunio shield connectors would stack, and new connectors would show up "elsewhere."   Even mere pin expansion would be reasonable; a shield board with an ATmega8 wouldn't be THAT much more expensive to build than a shield board with a couple if 74hc595s, and it would be a LOT more flexible.

What do you think ?

http://picasaweb.google.com/lh/photo/aNIGofgMSIJ6i17Xtshedg?feat=directlink

5167  Forum 2005-2010 (read only) / Development / Re: How much RAM is used? on: April 04, 2009, 12:07:29 am
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many tiny platforms have a non-enforced sliding barrier between heap and stack
Now that you mention that, I'm not sure.
So since this is coming up more and more frequently, I went and took a look at the initialization code in a compiled sketch.  It does in fact simply initialize the stack pointer to the top of the RAM area, and it is permitted to grow downward (toward the space occupied by malloc'ed data, uninitialized data, and initialized data) with no checking.  Also, malloc() does compare things against the current value of the stack pointer.   So it DOES have exactly the sort of sliding window between heap and stack that Halley describes....
5168  Forum 2005-2010 (read only) / Development / Re: How much RAM is used? on: January 13, 2009, 08:34:25 am
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many tiny platforms have a non-enforced sliding barrier between heap and stack

Now that you mention that, I'm not sure.
5169  Forum 2005-2010 (read only) / Development / Re: How much RAM is used? on: January 12, 2009, 08:21:20 pm
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when each function returns, the stack memory is freed up again.  Thus, it depends on WHEN you calculate free memory, to know how much you're really using.
Sort of.  The "unused" stack memory is still part of the stack, which is statically allocated on cpus like the AVR.  While free stack space can be used by other functions, it's NOT available for use by malloc(), or for static variables.

(This also means that there are two kinds of ram memory that you can use up.  Stack memory and "other ram."  In theory, for some applications you can save memory by putting variables that were declared at top level on the stack instead.  Or vis versa...)
5170  Forum 2005-2010 (read only) / Development / Re: Arduino Mega vs Sanguino (Why not adopt Sanguino?) on: March 26, 2009, 08:29:47 pm
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I assumed that the Sanguino team already did the core porting ...
They *did* it, but it has not become part of the Arduino "standard" distribution.  That means that when you upgrade from Arduino12 to 14 (or whatever), you have to re-install the Sanguino patches.

Worse is that this means that changes in the Ardunio core don't "automatically" happen for Sanguino, even if they are not inherently CPU-specific.  You'd got to apply the Sanguino patches to the Arduino code, and it wouldn't work, unless the Sanguino folks are very much paying attention.  (Still worse would be the case that the patch would apply, but result in code that operated incorrectly on both Arduino and Sanguino.)  And then there's the possibility of having XXXuino and YYYunino patches that are mutually incompatible :-(

(This is the sort of thing that makes ARM difficult to use (IMO.)  Sure, ARM is supported by gcc.  But if you want to support Luminary Cortex M3 cpus, you'll need the version X compiler from CodeSorcery, and if you want the NXP cortex M0 code you'll need their patches which are to a different base version, and this version of windows supports THAT download tool but not the other download tool, and ...  AARRRGGHH.  *want* Armuino!  Sigh.  (It might not be quite as bad as all that in reality.  But it LOOKS that bad...))

5171  Forum 2005-2010 (read only) / Development / Re: Arduino Mega vs Sanguino (Why not adopt Sanguino?) on: March 25, 2009, 12:38:21 am
A good place to start is at http://www.avrfreaks.net
On their "devices" page they have nice one-page summaries, frequently including "Crossrelation" info (for instance, the Atmega168 page says "pin and feature compatible with mega48, more memory.")  There is also a "compare devices" tab that will let you add and subtract features and/or devices and display a table of matching CPUs and features.

AVRFreaks is a little out of date (no ATmega328 yet, for instance), and the information is gathered by volunteers and is somewhat uneven (for instance, ATmega168 crossrelations don't mention ATmega8 or ATmega88, even though the devices are "current" WRT the table.
5172  Forum 2005-2010 (read only) / Development / Re: Arduino Mega vs Sanguino (Why not adopt Sanguino?) on: March 24, 2009, 06:52:15 pm
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You can add new boards easily. Just go to Arduino directory, hardware subdirectory, edit boards.txt add whatever you need.
That only handles the options for the upload command.  Supporting a new CPU like Sanguino would also require editing the main wiring library source code.
5173  Forum 2005-2010 (read only) / Development / Re: Wiring vs Arduino Mega on: April 01, 2009, 10:49:08 am
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Wiring and Arduino Mega is more like... umm... Unix.
I'll accept that comparison.   And how many different linux distributions are there these days?  I rest my case!
5174  Forum 2005-2010 (read only) / Development / Re: Wiring vs Arduino Mega on: April 01, 2009, 02:12:47 am
I dunno.  There are a lot of "niches" in the marketplace for a lot of products.  I don't think that Parallax Basic Stamp sales have been hurt very much by the advent of Arduino, though perhaps some of those $70+ 24-pin things deserve a little less success...  Wiring could easily survive in education markets just by stressing "curricula" rather than "projects."
5175  Forum 2005-2010 (read only) / Development / Re: Cheap shield compat board for finished projects? on: March 17, 2009, 03:14:47 am
But the original poster was specifically looking for a "barebones" board that was still compatible with shields...
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