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4936  Forum 2005-2010 (read only) / Development / Re: arduino with at90s8515 on: October 12, 2009, 01:07:59 pm
The AT90S8515 is an "old-style" (one of the very first) AVR microcontrollers, and it does not have the SPM instruction or the ability to self-program its own flash memory, which is necessary for a bootloader-based environment like Arduino to operate properly.  Basically, you can't use an 90S8515 without a specific "device programmer" module, and one of those is comparable in price to a full Arduino (even the cheaper versions will likely cost as much as an Arduino clone.)

There is a newer AVR that is similar to the 90s8515 (ATmega8515), but except for pins it has less capabilities than even the older Arduino chips (like the ATmega8)  Arduino variants like Sanguino ( that use a 40-pin chip seem to have settled on the ATmega644.
4937  Forum 2005-2010 (read only) / Development / Re: Typical distributor markup? on: October 14, 2009, 07:31:06 pm
The typical number thrown around is about 40% at each level of distribution.   So your $30 arduino should be costing about $11 to manufacture (which sounds "about right.")  The other number I see a lot is that retail prices is about 5x the "parts cost" (where "parts cost" is something like "major chips + pcb" rather than a detailed summation.)

There was a Panel at Maker Fair (featuring Limor and others), and it was pretty good.  All panelists were pretty big on "DON'T set your price too low" (and the mark-up IS bigger than you'd like.)

You can probably go lower than 40% if your whole distribution network is "open source aware" and wants to discourage people from just going off and making their own.  You probably need to go higher if  you want your product to show up at Radio Shack or Fry's.  (I've seen some interesting articles on sales strategies at such stores - you don't push sales of the "expensive" items, you push sales of items where the retail markup is large...)
4938  Forum 2005-2010 (read only) / Development / Re: atmega328 setup help on: October 16, 2009, 01:25:42 am
I drew this 'modularized' version of the Arduino schematic, which will eventually get some accompanying text and be a "definitive" answer to this sort of question.  Until such text is written, perhaps just the schematic will be useful to someone.  The idea is that each "boxed" section can be included or omitted in a "reduced" implementation...

The "core CPU" box is the minimum requirement (but it will required using an 8MHz build environment.)
4939  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 11, 2009, 05:22:01 pm
Much nicer!
Convention is that positive voltage symbols point "up" and Gnd and negative voltages point down.
You might want to add a bare pad on the max232 signal you're not using.  That might permit you to connect it with a jumper wire later if you find a use for it...
4940  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 03, 2009, 03:55:34 pm
why a connection from VCC to ground is needed. It's for noise suppression.
Note that this is not a "connection" from VCC to GND; it's a CAPACITOR between VCC and GND.
4941  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 03, 2009, 03:52:41 pm
There are standard eagle libraries "supply1.lbr" and "supply2.lbr" that contain assorted symbols and signal names.  (the actual "arrow" components I used.)  When you attached them to a net, it names the net to the appropriate signal name, and all nets with the same signal name are connected whether there is a  wire drawn between them or not.  (this also means you can draw a short net connected to a pin and use the "name" command to connect that piece of wire to the net with the same name.)
4942  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 02, 2009, 10:58:34 pm
[quoteexplain to me what the arrowing at the end of V+ pin mean[/quote]
In order to avoid cluttering schematics with wires to the power supplies, it is common to use a common symbol to indicate "this is connected to the common gnd", or "this is connected to the common +5V", or whatever.  All of these are "invisibly" connected (or treated as the same connection, because they enforce the same "net" name.)  The arrows you see are a somewhat common symbol designed to show this connection.  You might also note that the max232 symbol I used (which is from one of the standard eagle libs) doesn't have power supply pins shown on the schematic.  These are also "invisible" and automatically connected to the like-named net.

In (large) professional schematics, it's pretty common to reserve an entire page for nothing but the bypass caps.
Actually, in large professional schematics it's pretty common for each signal to come off a pin to some sort of named arrow, with no actual drawing to show where its connected to, which can be pretty annoying (but I don't know how else you handled 100+ pin chips without making a mess...)
4943  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 02, 2009, 08:36:58 pm
My eyes hurt.  A schematics is not supposed to look like a maze!
Here's my drawing of a similar circuit (but it hasn't been tested either.)
4944  Forum 2005-2010 (read only) / Development / Re: How to break or block internal arduino process? on: September 30, 2009, 06:54:31 pm
For all practical purposes, there is NO "background process" in arduino.
However, the level of abstraction provided by an arduino function call like digitalWrite(pin, val) makes it MUCH slower than something like "sbi PORTB,4"   About 20x slower.
There has been a fair amount of discussion on this in other threads.
4945  Forum 2005-2010 (read only) / Development / Re: Network audio player on: September 23, 2009, 07:35:36 pm
more a matter of sound quality
I wouldn't count on it.  The audio business is full of snake-oil and reverse frugality...
4946  Forum 2005-2010 (read only) / Development / Re: Network audio player on: September 23, 2009, 05:30:21 pm
I don't think that an arduino is particularly suitable for this task.
1) It doesn't have the CPU power to uncompress compressed audio.
2) (less certain) or to accept uncompressed audio-rate data over its network connection
3) no low-cost wifi
4) not enough memory to buffer audio streams in the face of network latency.

You might get it to work eventually.  Separate mp3 processor, bunch of add-ons.
Something like a BeagleBoard would be a more appropriate starting point.

However, this is the sort of "consumer" device that it is getting really difficult to build for less money than you can buy it for.   The £100 price tag buys an awful lot of electronics these days.  Have you considered looking for a cheaper commercial product?  "squeezebox" is a sort of brand-name "premium" product.  How about
4947  Forum 2005-2010 (read only) / Development / Re: Maybe the cheapest PCB service? on: September 21, 2009, 11:02:01 pm
So it is better to not get them open source unless you can only use 5 boards...
I think the "usual" case involves needing LESS than 5 boards, so the net effect is that your minimum entry cost goes down by letting Seeedstudio dispose of some of the extras instead of trying to do it yourself.  That sounds pretty reasonable to me...  (admittedly, there's a big difference between "I need one of these for my project" and "I need 30 of these for my class" and "I need 500 of these to strike it rich.")

I wonder what they charge for rev2 of your open source project, after you figure out why rev1 (published and all) didn't actually work?  (at least, one of the things that always stops me from using professional board shops is my low confidence that MY work doesn't have silly errors.)
4948  Forum 2005-2010 (read only) / Development / Re: Drilling holes in a DIY-PCB (the cheap way) on: September 20, 2009, 09:01:49 pm
I have vague recollections of drilling early PCB holes using a broken sewing needle and a hand-drill.
(the sewing needle, being hardened steel, breaks with a ragged end that is nice and abrasive.)
4949  Forum 2005-2010 (read only) / Development / Re: Eagle and SCRs on: September 12, 2009, 04:21:36 pm
Like the Capt said; try a search for *thyr* instead...
4950  Forum 2005-2010 (read only) / Development / Re: Diecimila gerber file on: September 09, 2009, 01:10:33 am
There's an interesting question WRT open source hardware about just how much trouble the "providers" should have to go to to make sure "users" can actually use them.  In the old days, vendors would sometimes provide "reference designs" for their more complex chips, and that would usually have a printed schematics and PCB layout "picture", plus sometimes a set of Gerber files so that you could reproduce the circuit board, and maybe a "bill of materials" so that you could know exactly which parts the board was designed to hold (a 47uF cap comes in a bunch of different sizes, for example.)  That was ... something (and there are a lot of products out there based on reference designs), but if you wanted to make slight modifications of the design, it meant manually entering the schematic and PCB layout into some tool set that you owned; nearly starting from scratch.

The model used by the more "modern" open source projects (like Arduino, or the EMSL projects, or Adafruit) involves releasing the design files for some CAD package in a easily machine editable form.  EAGLE is particularly nice, since CadSoft has EAGLE running on all the popular operating systems and has the freeware version around for anyone to use (for non-commercial purposes.)  But it is certainly not required that design files be in any particular format, and even designs written in obscure and expensive CAD packages could still be legitimately "open source."  (EMSL uses GEDA (itself open source SW), Solarbotics released their freeduino design in Protel format, and MDC released some of their designs in OSMOND, to mention a few examples.)

Likewise, it's not required to release open-source hardware designs in "ready to manufacture" form (gerbers, in particular.  Gerbers pretty much suck as a descriptive/educational format, aren't easily editable, and are relatively obsolete from a technology point of view.  But they're what the board houses all know how to deal with.)  Asking the original developers to generate gerbers for you is a bit like asking the open source SW community to compile a program for you; not beyond possibility (witness the large number of binary distributions for popular packages), but not really within what you should EXPECT, either.

What kind of trouble did you have exporting the designs using EAGLE?
(and WHICH serial design were you talking about?)
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