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5161  Forum 2005-2010 (read only) / Development / Re: Help with eagle and SMD on: March 06, 2009, 02:09:38 am
In the "autorouter setup" tab, change the routing grid from the default (0.05 inch) to something at least as small as the minimum pitch on your SMT packages. (0.01 inch is probably good.)

Also check the design rules and make sure they aren't set such that "legally" routing to the SMT pins is impossible (if you have a package with pins on 0.4mm centers, placing 0.2mm traces at least 0.2mm apart is a challenge...)
5162  Forum 2005-2010 (read only) / Development / Re: Where do I find SmartPrj CAD library on: March 09, 2009, 10:24:38 am
In theory you don't need the library to modify the circuit, since there is a full copy moved into the .sch file.
There is an EAGLE "ULP" that will export all the parts from a particular .SCH into a .LBR (exp-project-lbr.ulp)
5163  Forum 2005-2010 (read only) / Development / Re: atmega328P on 1.8v on: March 01, 2009, 08:54:49 pm
There are two philosophies about keeping low power consumption.  Certainly lowering the clock rate lowers the power consumption, but the other idea is to have the processor spend most of its time in low-power sleep modes, then wake up periodically and run at high speed so you can get back to to low-power sleep mode as soon as possible...
5164  Forum 2005-2010 (read only) / Development / Re: [DIY] (protective) mask for selfmade PCB on: March 02, 2009, 07:24:21 pm
Are you just trying to make it look prettier?  After it's all done you can probably use any sort of spray clear-coat on the solder side, but I wouldn't do that before soldering on components.  There are some spray-on coatings that serve as flux ( plus LOTS of special-purpose "conformal coatings" designed to protect PCBs from all sorts of highly specified environmental "issues", but they tend to be very expensive.

There are also assorted products for tin-plating your PCB.

Frankly, if you're going to solder your board relatively soon after making it, I don't think any of these are worth the trouble.  While the copper traces will oxidize on the surface, the oxide is a bit like Aluminum oxide - it's protective of the remaining copper, and the PCB will stay in working condition for decades (while at least one of the tin plating products I was looking up contains exactly the sort of fluxes that you are NOT supposed to used on electronics...)  It'll just look not so pretty...

I don't think I've ever seen a home fabrication friendly soldermask material that actually works as a soldermask (ie holds up to soldering heat on nearby parts of the trace.)  THAT I'd like to find  (I think "real" soldermasks tend to be 'cured' epoxy-like things, nasty and difficult to deal with in home environments...)
5165  Forum 2005-2010 (read only) / Development / Re: Increase battery life with Switching Regulators on: February 16, 2009, 03:31:54 am
if your IO pins are connected to other IO pins, they won't actually draw much current and adding resistors won't help much.  If you're driving things OTHER than other IO pins, there may be real current requirements and adding excessive resistance would not be a good idea (read your spec sheets carefully.)

If you have "pull up" or "pull down" resistors on IO pins connected to other things, it might indeed be a good idea to increase their values to decrease power usage...
5166  Forum 2005-2010 (read only) / Development / Re: Increase battery life with Switching Regulators on: January 09, 2009, 07:03:33 pm
If my application need 50 mA with 5 volts
With a PP3 (9V) battery, and needing 5V@50mA, your circuit is using 250mW, and the linear regulator is dissipating approximately 4*0.05 = 200mW, for an overall efficiency of 250/(450) of about 55%.  That's not too bad for a linear regulator.  Simple switching regulators probably won't be getting more than 80% efficiency.

You might want to look at other battery choices.  Two AA batteries contain a lot more energy than a PP3, and a switching boost converter is no harder than the switching step-down.  In fact, there are a lot of products specifically aimed at boosting a couple batteries to 5V, and they're already "battery conscious" (which a step-down might not be.)
5167  Forum 2005-2010 (read only) / Development / Re: What can I take off from the single sided board? on: February 18, 2009, 09:05:18 pm
In my experience, if you're laying out a new SS board, you get the most simplification from leaving out the ICSP connector (which otherwise requires several signals be be routed in two directions instead of one.)
5168  Forum 2005-2010 (read only) / Development / Re: AVR with embedded USB? on: February 03, 2009, 03:29:11 am
Virally oppressive? Don't you mean "Downstream protective" ?
You may disagree with me, and I might even be wrong, and this is certainly not the place to debate the issue in detail, but "virally oppressive" is exactly what I meant...
5169  Forum 2005-2010 (read only) / Development / Re: AVR with embedded USB? on: February 02, 2009, 11:40:09 pm
we could be forcing you to use GPLv3
Just curious: Jestersage, just who are you,  to be using "we" so ... dramatically?  Which pieces of code have your written and kindly released under something less virally oppressive than GPLV3?
(I note that Mellis made rather encouraging complementary noises, without delving into open source politics.  In general, I think the arduino team members have done a really good job of treading the open source political lines, not always in their own favor...  For instance, I think the whole Freeduino controversy worked out pretty well for all parties, in the end.)

(Sigh.  So much for keeping my fingers curled.)
5170  Forum 2005-2010 (read only) / Development / Re: AVR with embedded USB? on: February 01, 2009, 11:22:48 pm
Carefully "curling my fingers" (the e-equivalent of "biting my tongue"), I'll just say that I suspect that the complexity of implementing USB devices beyond a simple serial port simulation is going to be a much bigger barrier to success of things like the teenydunino than a lack of "openness" in the distribution model...  The "USB-whacker" has existed in PIC-land for quite a while now, for instance...
5171  Forum 2005-2010 (read only) / Development / Re: AVR with embedded USB? on: December 08, 2008, 11:59:39 am
thanks for the info.  Having the separate dpram makes having half the normal ram a lot less worrisome...
5172  Forum 2005-2010 (read only) / Development / Re: AVR with embedded USB? on: December 07, 2008, 06:50:48 pm
Do the smaller AVUSB devices have separate ram for USB buffers, or are you talking about half the ram of a mega8 MINUS the usually-substantial memory used by USB ?
5173  Forum 2005-2010 (read only) / Development / Re: AVR with embedded USB? on: December 06, 2008, 03:49:53 am
1) None of the AVRUSB chips is particularly backward compatible with the CPUs currently in use.
2) Cost of ATmega168 + FTDI chip is less than any of the USB chips with equal RAM (1K or more.)
3) The FTDI chip comes with well-tested drivers emulating a serial port on all three popular desktop operating systems, making it easy for random applications to communicate with.  Getting to that point with an native-USB AVR would be a lot of work (and/or expense) for someone.
5174  Forum 2005-2010 (read only) / Development / Re: Limitations of 8 MHz on: February 18, 2009, 12:59:48 pm
Looking at one of the AVR baud rate calculators, it looks like the max "standard" speed you can use "reliably" at 8MHz is 38400.  This is more of a "the division doesn't work out" issue than a raw speed issue.
5175  Forum 2005-2010 (read only) / Development / Re: New Color LCD Shield for Arduino on: February 16, 2009, 03:42:56 am
Wow.  That's a really nicely sized display for an Arduino.  And it's smart too; not requiring continuous refresh?  And useful "extra" stuff on the board?  And rather reasonably priced!

How difficult to ship to the US?
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