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4966  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: working with multipel serial devices? on: April 19, 2010, 12:26:25 pm
How would you connect 17(yes thats right seventeen) serial devices(sensors) and get data from them to a computer? 17 USB ports seems too much to expect.

You must be young (that, or forgetful, or senile, or maybe you are like a lot of us and just block those memories - how I wish I could forget; the JD does nothing)...

A long time ago, 17 serial dumb-terminals (and line printers) spread over an office building was a small installation...


/I feel old...
4967  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Building a rover on: April 19, 2010, 03:05:00 pm
The biggest problem with a PowerWheels (well, other than needing high-amperage motor drivers, and a custom high-torque servo for steering), is storage - that thing takes up so much room in my shop (which isn't as big as I would wish to have - something the size of Costco would be a nice size).

4968  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Building a rover on: April 19, 2010, 11:33:45 am
A question I have: do you have the rover part of your rover, or do you have an idea of what you will use?

Scale is important here; the bigger the rover, the more you can put on it (to a point). For instance, I am building a "rover" - it is being based on a PowerWheels H2. So far, I know it can haul my fat butt around (200+ lbs), so my choices of what to control it with are nearly unlimited.

Which is why I am using an Intel ATOM motherboard with a PicoPSU running off on-board SLA batteries. I am using an Arduino merely for steering and drive motor control (as well as pass-thru for servo commands to a Pololu MSSC).

If you are planning something smaller, keep in mind power requirements of everything you are planning to use - sometimes, it might be easier to plan everything, build all the component building blocks, find out the power requirements from those experiments, then choose your chassis size based on that.

Depending on your needs and desires, you might find you need more processing power than you have battery to run it; I initially had a plan to use a smaller 2WD truck platform (a cheap New Bright toy truck) that was fairly big, but didn't have the power to allow me to put a full PC on-board (nowadays, though, I could possibly choose a BeagleBoard or similar micro PC mobo) - so I planned on using an RF interface of some sort, do all my coding and testing in that manner, then migrate everything together into the next step which was to be the larger PowerWheels base.

What ended up happening though is I found a colleague who had a spending problem; he went ahead (against my advice) and bought the PowerWheels - after he left the project, I bought everything back (he ended up liking the Arduino, and last I heard he was performing some gardening/growing experiments with it). So, we (and now I) have decided to stick with that larger platform and skip the initial one.

You could do something similar, though - off-load processing power to an external computer connected by xbee, RF, or some other wireless system (unless you are building it for a contest that disallows this). If you need vision processing, use a wireless camera and feed it into the "base" computer with a capture device and process it that way. Other sensors and such can send readings back via the wireless interface. This would allow you to have more processing power available than you have power (or space) on-board; in the future if you move to a larger platform, it can be easy to migrate.

Good luck with your rover!

4969  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Which pin controls the motors? on: April 18, 2010, 02:55:23 pm
Yeah, works great for double-sided and multi-layer boards!

For double sided boards, you can set up layers and invert/flip the bottom/top (whichever one you consider "the other side"), and alter the alpha channel for a particular color to allow "see thru"; stack them as layers in your editor, and alter the transparency to allow you to see the traces as you track them.

Obviously this won't work for multi-layer boards, but even in that circumstance using this method may reveal clues that can help you find nearby pins and such.

I know all of this from experience; many moons ago I was involved in the "hacking" of a set top box called the Acer NT-150, which inside was essentially a AMD 586/133 motherboard with extra components for TV signal mixing (among other things; it also had a built in smart card reader). People wanted to add a mouse, which it lacked; one of the members of the group showed me the solution he used for tracing pads from the Super I/O chipset to empty pads of what looked like a MAX232 chip on the motherboard - he and several others used this method over a period of about a week to reverse engineer the chip, which was then sourced, soldered in place, and gave the board back a DB9 serial port for a mouse.

So I know the method is more than valid for this purpose, even on a multi-layer board like a PC motherboard.

4970  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Which pin controls the motors? on: April 18, 2010, 02:26:39 am
To trace this easily, take the board, lay it flat on a scanner square with the edges, and scan it, both the front and the back. Play with the resolution; the smaller the traces, the higher the scan resolution you should use. Then use a tool like PhotoShop or the Gimp to flood fill the traces (filling "similar" colors) from part to part, via to via, in a contrasting color (yellow or red work well). This is a real handy way to trace and reverse engineer a board, even when it has small, close-together traces for SMT work; just increase the resolution of the scan to make everything larger so the flood fill can work properly. Its not a perfect method, but when used in conjunction with standard tracing methods (namely looking at it until your eyes bleed), it can be a great help.

4971  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Where to start? on: April 16, 2010, 06:21:18 pm
The easiest "main piece" to get is the bog-standard Arduino Duemilanove, like this one:

Gotta love the PID (product ID)!

Anyhow, this is really the "basic board" that you can start with (comes with the 328 - you don't see many boards out there anymore with the 168 or smiley-cool.

Most shields and such are designed to work with this board; as your skills progress, you can look into offerings in smaller packages (like the Pro or Nano, or even the LilyPad).

If you like a lower profile (and don't mind having a non-removable version of the ATMega on-board), check out this one - it uses a mini USB connector, and all smt parts to keep things low to the ground, so to speak (the small USB connector is kinda nice; some shields have components placed over/near the standard USB port on the Arduino, and you have to put a bit a tape over it to keep it from shorting):

It also has other features that can be handy to users.

There are plenty of other variants available that incorporate different things on-board instead of on a shield (on-board wi-fi and ethernet are becoming a popular thing), but the standard Arduino is still what I think most people use and develop with.

4972  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Need ATmegas TQFP Package on: April 16, 2010, 05:14:23 pm
other than China-shipping takes too long

You are probably SOL then, unless you can find a kind soul who has some available (and isn't hoarding them because of the same issue).

Have you tried contacting any of the asian suppliers (by phone) and purchasing what you need (a tray's worth would probably be the minimum if you get very lucky) and having them FedEx'd overnighted? Have you contacted Atmel directly (again, by phone) and asked for the same thing (although they probably want a huge order; but maybe you could get friendly and they could help you work something out with one of their manufacturers in China to do the FedEx thing)?

Unfortunately it seems like a lot of stuff right now in the uC marketplace (and peripheral stuff) is only available from China; I am not sure exactly why, though...

Good luck!


[edit]Researching on another topic, I think the reason why there are so few available on the market has to do more with the fact that Atmel has only a single fab line right now (in Colorado Springs), and what stock was available was (mostly?) bought up by suppliers in China...? Not sure...[/edit]
4973  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Projections? on: April 16, 2010, 12:16:51 pm
As a neat 'addon' for this i thought of some sort of HUD for the frontal glass

If this is for car usage, you probably can't put a piece of frosted glass or film on your front window (might violate some vehicular window tinting or such law - check your local laws). Does it need to be for day and night, or night-time usage only? If night-time only, then you might be able to get away with reflection off the glass (though you will need to come up with some other method to undistort the image).

4974  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Projections? on: April 15, 2010, 12:29:35 pm
Also - is it possible to 'beam' such projections onto glass?

If the glass is frosted or ground (for back projection) it would. But it would need to be a fairly bright image. As Osgeld noted, I doubt that the LCD "opaque" state is as opaque as needed for such projection (this is the "black" contrast issue you see on LCD TVs, for instance). Also, I doubt you will be able to dissect a GLCD to the point of adding your own backlight.

I am not absolutely certain, but I think the way those alarm clocks work is by using bright 7-segment (or 5x7) LED displays, and then a simple magnifying lens arrangement for the projection - rather than LCDs.

4975  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: standalone? on: April 15, 2010, 12:16:08 pm
surely you cant be disappointed in me.

I suppose I have higher expectations of people; I keep forgetting that we let AOL users join the internet...


you dont even know me.

I know enough about you from your words. My opinion so far may change as time goes by, so please, keep talking.


if your disappointed in the human race....your too young to carry that burdon!

Actually, I am very disappointed in the human race, on many levels. What could be achieved via cooperation rather than struggle, for instance, would dwarf everything that has so far occurred on this planet. The fact that we haven't destroyed ourselves (yet), though, does give me hope.

This, however, isn't the forum to discuss these issues, so I won't say any more on the topic (perhaps bar/sport would be a better forum).

4976  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: standalone? on: April 15, 2010, 11:49:14 am
[edit]I really love this one[/edit]

That would definitely confuse the hell outta people if we set up estranged's system...

4977  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: standalone? on: April 15, 2010, 11:16:59 am
anyway if you do the maths you wasted more time gettin all raged up than it did for "grumpy"_mike to reply. a tad counter-active imo.

Not rage. Disappointment.

btw - your words speak a lot; thank you for writing.
4978  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: standalone? on: April 14, 2010, 03:13:55 pm
It's not the answer I wanted, but it was the answer I expected.

I am beginning to take the tack of not responding to these easily answerable questions; I can certainly understand some questions that are difficult to answer (ie, "How do I tune my PID?", among many) or reveal so many options as to be nearly overwhelming to a newcomer.

Your question was neither. Your question could've been answered just as quickly (if not quicker) and just as accurately, had you typed it into google than into this forum.

You've done nothing more than waste a wee bit of mine and Grumpy Mike's time, due to sheer laziness and/or apathy; I am not upset or angry, but I am a little annoyed. I don't know how Mike feels, but he should feel worse than I, since I didn't answer the question, and I willfully came into this discussion with a question of my own to you.

Rather than being lazy, next time be proactive and take a stab at google; 9/10 times you will find the answer there. If you can't find it there, search the forums here. Nobody is so busy as to not be able to do that, and if they are, then electronics and the Arduino probably isn't the hobby for them, as both take time and patience for full understanding (and without understanding, especially when it comes to electronics, you can end up dead quick depending on the situation).

Perhaps you schedule your time out (hopefully not to the minute though; such planning of a life seems to me a sad way to exist); if so, then you likely have a "work on arduino" time slot - do your search then, write it down or make a memo or set up a reminder alarm for it if you have to.

Only if you are unable to find an answer, or you find so many anwers you don't know where to turn, then post the question. This is something that should be general netiquette, but for some reason isn't.

Oh well.

4979  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: standalone? on: April 14, 2010, 11:02:28 am

I am curious about something; you had a question, it was answered fast, that's great, right?

But why did you ask the question in the first place? What I mean is, this particular question is asked at least once a week, if not more often, so what was it that prevented you from finding an answer?

Even if you couldn't navigate the site well (is this an issue?), you could go to google, type in "arduino standalone", and...

The first link would take you to the page Grumpy_Mike posted.

So what prevented you from doing that?

I am honestly curious and I want an answer that makes sense, because it would only help to improve the site and resources for new users. Back in the day, one had an excuse that they didn't understand a card catalog or the Dewey Decimal system - but that excuse doesn't apply anymore in the age of Google...

/I miss microfiche...(not really)...

4980  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Android/iProduct app interface with arduino? on: April 09, 2010, 04:07:40 pm
This seems interesting:

I also read some stuff about people working to get USB OTG working; there was this for instance:

Wish I had the time to play with this stuff...

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