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1  Products / Arduino Due / Re: My new Due is dead. on: February 06, 2013, 10:15:27 pm
Quote
so I have a non-conductive antistatic foam

That sounds like an oxymoron, like jumbo shrimp, or Federal Service. How does a non-conductive antistatic device work anyway?  smiley-wink

Lefty
...or Army Intelligence, or analogue logic...

I meant low-conductivity foam. It's not a pure insulator, so static doesn't build up on it. But at about 20Mohms/cm, it doesn't affect CMOS logic circuits like the 20k/cm stuff that you get from electronic shops does, if you accidentally get some beneath your connectors. Now that's another story altogether... Sigh.
2  Development / Suggestions for the Arduino Project / Re: Lots of mechanical stuff... on: January 27, 2013, 11:20:04 pm
That's a great shield! Probably overkill for my needs (I'll be designing the Arduino right into the production PCB), but as an experimenter's tool, it's fantastic. And cheap too!
Thanks for the suggestion.
Cheers,
PtB
3  Development / Suggestions for the Arduino Project / Lots of mechanical stuff... on: January 27, 2013, 09:22:04 pm
I'm very new to the Arduino scene, although I've been designing, building, and fabricating MCU projects for nearly 20 years now.

I like the Due, my Arduino-of-choice, very much. However, there are a few suggestions I'd like to see implemented that would make my life as a designer a LOT easier! In no particular order, these are :

1) More low-impedance digital and analogue ground points, please! 2 0.1" sockets isn't near enough when you're designing the Arduino as the core module of a complex system - and even just on the bench! If we connect more than two external devices, we're straightaway into piggy-back grounding, which is dangerous, and there's just no simple VCC/GND connector that would help tremendously!

2) Level shifters for ALL 3V3-only pins. THis takes a 2 or 3-cent fet, and would allow anyone to connect anything to the Due, without worrying about a poofteenth of a microsecond contact blowing up the ARM! Been there, done that, got the smoke to prove it (luckily, not the Due, that died of something else...)

3) Headers for all analogue, digital port blocks, etc, would be a great convenience. For example, a micro-spaced 9-or10-pin SIL or DIL header per port block (PORTA, PORTB, etc) would be a huge convenience when connecting stuff like LCDs, etc. Plus, they run faster.

4) Switchable indicators.

5) Additional switchable indicators, such as LED arrays (8x1) with built-in resistors, so that we don't have to string LEDs all over the place. Plus, it would be a great debugging tool. Unless there's already something out there?

I realise some of these could be (or already are) addressed by shields, but as a completely novice Arduino person, the single two most frustrating things were finding connection points for good grounds for scope probes, logic probes, and so on, and the 5V AutoDestruct port pins. There is so little 3V3 support equipment out there, it's a huge disadvantage to have to check every possible pin, etc. Obviously, this is good for maybe pushing developers to meet the 3V3 hobbyist demand, but that will take months to years. In the meantime, a few convenient, though admittedly quite complicated to fit, additions could make the Arduino from a bit of a toy platform (in terms of test equipment attachability!) to a good engineering-grade platform. And everyone would benefit, not just engineers (I'm not one, by the way!).

THanks for the opportunity to provide some feedback on this great little platform. And of course, if these have already been suggested and knocked back, my apologies for doubling down.

Kind regards,
Pete the Builder.
4  Topics / Robotics / Robot-based website on: January 27, 2013, 09:07:03 pm
G'day everyone!

I've noticed quite a few similar sorts of questions popping up about sensors, how they work, and I've noticed a few folks really have no idea about power management, all those little "non-Arduino" kinds of questions... Well these are questions we all have to learn!

I have a robot-based website that some folks might find helpful to try and understand some of the more mechanical and fundamental topics (gee, we have to know so much about so many things to do a robot correctly!).

The site is Rocky the Rover's home page!

The site is a little out of date regarding the newest sensors and specs, but hopefully the general ideas will be helpful to many folks. I've been in hospital on and off since my last update of the site, and Rocky's in a big box in the cupboard for now, but I'll try and put in some updates if anyone wants to know something specific.

I hope this helps, and gives some people some ideas! Questions, comments, or suggestions are most welcome!

Cheers,
Pete the Builder
5  Products / Arduino Due / Re: My new Due is dead. on: January 27, 2013, 08:52:25 pm
No, I didn't think of the polyfuse. Thanks for the suggestion, I appreciate it!

And I believe I have lied to you all. I hadn't touched the board after it fried, so this morning when I went in to the morgue, I noticed something I missed yesterday...

I had a lead connected to the barrel of the DC jack as a low-impedance ground for my circuit (pulsing a small detector coil). Today, I noticed that the lead was right next to the USB shield (shield as in the metal jacket around the PCB connector, not shield as in an Arduino shield! Or a hoplite, either!). It is entirely possible that this big, heavy ground wire could have connected with the USB parts. It would have been from the top, not the bottom (I'm paranoid about stuff getting under any of my boards, so I have a non-conductive antistatic foam dam around the board's underside), so the fuse issue may actually be what went wrong...

Now that I've seen that potential hazard, I can't claim to know for sure what the hell happened. Sigh.

I contacted the local vendor, who, like most other vendors I've spoken to this morning, are completely out of stock of Dues. Which is good, I guess - they're obviously going to be tremendously popular! But it makes it frustrating for an Australian developer with only Paypal.

Still, at least knowing about the polyfuse gives me some incentive to break out the USB microscope and look for clues. Heck, I've got nothing else to do! smiley-confuse

But thanks for reading everyone, I appreciate the virtual support!
6  Products / Arduino Due / My new Due is dead. on: January 27, 2013, 03:45:16 am
While I was trying out the example project "AnalogInOutSerial", the pot was fully turned to the 3V3 end of its range, and the wiper wire came out of A0 socket pin and brushed against the Native USB shield (around the USB connector). I thought nothing of it because it was an extremely low impedance ground. That's what the shield is for.

I reconnected the wire, and for some reason the LED stayed completely off. I checked the wiring, it all looked right, but the connector felt warm. I brushed my finger across the ARM and it was smoking hot!

The board is now utterly dead. When DC power is applied (7V), the regulators overheat and the ARM chip smokes within 10 seconds. Disconnecting the DC jack and plugging in the Native or Programming USB ports faults my USB powered hub. So this is a dead parrot.

Here's a lesson for anyone playing with the Due : DO NOT, UNDER ANY CIRCUMSTANCES, ALLOW ANY CURRENT TO FLOW THROUGH THE USB BACKSHELLS!

Looking at the circuit, the only thing I can see that would possibly cause this is if the USB ground was not low impedance enough, AND the input voltage dropped enough when the short occurred that the regulators went out of regulation, in which case, the D+/D- active dampers Z1-Z5, may have conducted the full 3V3 to the Data lines for just an instant (but why would 3.3V be a problem? Only makes sense if the regulators were shorted) and deep-fried the ARM.

In case anyone thinks I might have mistakenly connected the pot to the 5V rail, I was particularly careful not to. I cut a set of SIL pins to suit the connector, and specifically pulled out the 5V pin so there was no possibility of accidentally soldering the pot wire to the 5V pin, because the 5V pin is not there.

This is really frustrating. I can't believe an experimental board could fry so simply, with a single loose wire. Unbelievable.

I'd be happy to return the Due to the designers for fault analysis. Hey, it's $60, but I have plenty of PICs that I can use in the meantime.

So do keep your wires clear of the board at all times. And as I said, don't, under any circumstances, short anything to anything!
7  Products / Arduino Due / Re: Request clarification re: Powering the Due on: January 27, 2013, 12:07:45 am
Thanks, guys, that's been really helpful.

I think I've got the gist now, after doing what I should've done in the first place - check the schematics! smiley-red

In fact, it's best to power the board from the DC jack under all conditions, and to use the USB power option only when no DC power is available. The USB ports can provide power, but (as has been pointed out) not when the board is acting as a host, since it has to provide at least 100mA of USB power to meet the spec (technically, for faster USB modes, it should be 500mA). That's why you can't power from the USB and power either USB bus (oh dear, "PCB board" anyone?)

So thanks again. It's all coming together now, and no smoke has been released!

Cheers,
Pete
8  Community / Website and Forum / Re: Help for general editing on: January 21, 2013, 08:29:46 pm
WTF? I just did exactly that, but instead of a hyperlink, I got the whole tag as plain text! Now, when I tried it again, it works! (No, there was no missing brackets, etc...) Hmm. I'm using Chrome on OSX, I might try updating to see if that might help.

As long as it's made clear somewhere that BBCode works, that should be helpful... though not as helpful as having the usual "BBCode Help" link visible.

Admins, would you care to comment? Is this feasible? (Having some editing help link visible somewhere onscreen?) Or are you trying to keep the interface as uncluttered as possible so new users aren't intimidated?

Thanks for the response anyway, Osgeld, it's much appreciated, even if only to confirm the PHBbb/BBCode stuff *should* work!

Cheers mate!
-Pete
9  Products / Arduino Due / Request clarification re: Powering the Due on: January 21, 2013, 08:16:04 pm
G'day all!

My crisp new Due arrived last night, and I can't wait to let the smoke out power it up.

But I have some serious questions that need to be clarified. Hopefully the answers will be helpful to the many others asking similar questions!

OK. The Due info sheet http://arduino.cc/en/Guide/ArduinoDue is quite confusing, as it says that the board may be powered from the USB port, but then a paragraph later it says it can't, and it must be powered by the DC adaptor if the board is a host.

So could we get some clarification, specifically :
-for testing, "first light" purposes (i.e. out of the box), what is the best method for powering the board?

This isn't explained anywhere, and would be an excellent item to add to the blurb sheet that ships with the unit, just so we know. A simple line diagram would be very helpful to prevent any potential release of smoke.

- Can I program the board when it's just being powered by the Programming USB port?

- Should I also remove any Native USB device at that time, or is it safe to leave in? In other words, can both USB connections be powered simultaneously, if I'm using the Native port from a powered hub, etc? Following on from this...

- If I have a (second) USB target connected and powering the board via the Native USB port, when programming, can I just stick in the Programming USB connector, or should I only ever program on DC power?

Perhaps a simple "howto" thread, aimed at novices (I've been designing and building MCU projects for over a decade, but this is my first ever Arduino) could help prevent accidents and frustration. Could another Arduino image be used for this?

Ummmm... I think that's it for now. I hope this generates some interest and helps to improve the documentation. I'm happy to help out in any way I can - but right now, I know nothing!

Cheers,
Pete
10  Community / Website and Forum / Help for general editing on: January 21, 2013, 08:01:16 pm
G'day all, I need to understand the quirks of this forum's software, as putting in links and stuff doesn't seem to accept any of the usual syntax for forum software. For example, BBCode doesn't work the way I'm used to, etc, etc. I realise this is being kept simple for a reason, but I'd like to understand what I can and can't expect to be able to do in a forum post.

There's nothing I can see that helps a newbie to this site, which is REALLY frustrating smiley-mad. The Help link at the top right goes to an essentially blank page, and trying to solve my questions (without asking what seems to be a very silly question) doesn't work either.

In fact, the search tool can't even find the word "url"! smiley-eek-blue Nor does the search tool work as expected with quotes, etc, and the advanced search tool doesn't actually search the Due forum at all! smiley-yell

So any advice on where to find the "User Manual" for the forum software would be very much appreciated! And of course, if this information is clearly available, please accept my apologies... and please tell me where it is! I must be going blind! smiley-draw

Thanks everyone!

-Pete

P.S. I'm not just whinging, I'd like to help get this kind of info posted in one place so people without any knowledge at all can at least do a search or see a sticky. Depending on the results of my questions, this could be the first step! Woo Hoo!  smiley-grin
11  Products / Arduino Due / Re: Did I damage my board? on: January 21, 2013, 07:29:10 pm
Hello,

I am trying to communicate between a DUE and an UNO via I2C.  I had the communication wire up with a pullup resistor to 5V.  For about 5-8 minutes I was trying to debug why the UNO wasnt receiving any information and then I realized that the DUE's tolerance is 3.3V. 

Could giving 5V to these pins (SCL1 and SDA1 on the DUE) for about 5-8 minute damage the board?  If so, how can I check?

Daniel


G'day Daniel!
How did you go? Did you manage to read the ports as Leon suggested?

FWIW, the potential for damage using pullups is limited to the amount of current the resistor supplies to the port pin. If it's less than the clamp diodes on the input pin can handle, you'd be fine, though I wouldn't make a final design like that!

Note that there are some brilliant examples of single-FET (like 2N7000) level-shifters that will work fine with I2C (I used them on an eZ80 at 1MHz and they worked perfectly!).

The ONLY catch I can see, is if the remote system's I2C pins were in non-open drain mode (i.e. if the device was reset and the pins weren't configured for I2C while the Due was connected). In that case, I would suspect that both devices would be suss, at least on the I2C pins, and possibly any circuitry on the die close to them. Sorry.

But, fingers crossed, let us know how you got on! You are the Guinea Pig!
12  Using Arduino / Project Guidance / Re: Arduino Due-based metal detector project - finding meteorites! on: January 21, 2013, 07:15:34 pm
Mike, yes, I'm aware of the amazing range of compositions and formations of hot rocks from the sky!

I'm actually trying to find some scientifically interesting metallic meteorites, so one of the parameters of the design will be the ability to detect nickel. Since I'll most likely be prospecting well away from any human presence, I don't really care about coin clutter. The added benefit is the presence of a high amount of nickel and bismuth in the gold ores around here, so I don't really mind if it's a meteorite or a nugget!

With all that said... It looks like I was sadly mistaken at the initial approach I was following. So I've subscribed to the GeoTech forums, where people MUCH smarter than I are doing some incredible things with PI and discrimination. All else being equal, it should be possible to harness a good coil design and front-end to a Due and do some phenomenal things with a little bit of maths!

The only thing that scares me about that sentence is the word "maths"... Sigh. smiley-sad-blue

But thank you so much for your interest and comment - I live to learn.
13  Using Arduino / Project Guidance / Re: Arduino Due-based metal detector project - finding meteorites! on: January 20, 2013, 01:09:10 am
Thanks for the suggestion! I actually requested an update on that thread before posting this one... I'll still keep an ear open though...

Without boring the pants off you, the metal detector works simply (ha!) by pulsing a largeish horizontal coil at about ground level, then watching for a reflected and modified magnetic field. That's it!

Well, after ignoring the 450V spike from the TX coil, about 40-90 uS later, any metal in the ground will be detectable via a tiny (~50mV) decay slope after the spike. After another 200uS or so, it's all over, and the cycle begins again.

So the magic all happens between 50 and 200uS after the spike, that's where the ADC needs to capture as many samples as possible.

I misread the Due specs, too - I should be able to get 1uS samples happening with the native 12-bit ADC. That should be more than enough to provide spike end timing, plus a sliding window of a couple of hundred 4096-scale conversions, at a resolution of roughly a mV per LSB. That's actually as good as, if not slightly better than, the upper-mid-range commercial detectors on the market : in the $800 - $2,500 bracket!

It all depends on the maths. And, since I'm a 'silicon guru', but a mathematical Neanderthal, I have a lot to learn!

You're right, the Due seems to be an excellent package for everything I need in this project. The hardware will probably be minimal - a couple of fast, low-noise op-amps, a couple of analogue switches, a handful of precision caps, and a long learning curve!

I can't wait for the module to arrive...
14  Using Arduino / Project Guidance / Re: Tracking Animal position and temperature on: January 18, 2013, 03:39:02 am
Skyjumper, 5ha is 5 hectares (roughly 60,000 square yards). It's how us weirdos in the rest of the world measures areas larger than a couple square metres  smiley-grin (actually, I grew up with acres, and I have not the slightest concept of a hectare, although I have to know what they mean!)

Yes, I realise the figures I gave were for constant current, and that sleep mode is much more useful in a project like this. It'll reduce the power drawn by a factor of 10 or more, depending on the ratio of sleep to on time, of course.

Thinking about the OP's project, it would make much more sense to just store the readings on a flash card every 5 minutes or so, and not even worry about WIFI, unless real-time updates were needed. (Heck, knowing sheep, it could be even easier to log just the change (if any) in temperature and position, using integers!).

But worst case, I'm guessing a single NMEA sentence plus a 16-bit integer, 12 times an hour, for 15 hours. No need to worry about overflow. Would it fit in RAM, I wonder?

ANyway, hope this helps.
15  Using Arduino / Project Guidance / Re: My body gives Electricity when i trying to acquire signal by AD620 inst. amp ? on: January 18, 2013, 03:19:02 am
The square wave you are seeing may be due to 50Hz mains pickup. You're in England (or Ireland/Scotland/Wales), I assume?

You can try a couple of things. First, check the frequency of the square wave. If it's 50 or 60Hz, it's mains interference. If you're running the circuit from batteries, you don't need high resistance in your electrodes. Try reducing the resistance to about 10k, that should significantly reduce the mains pickup.

If the square wave signal is in the frequency range you're interested in (200Hz...20kHz), then add a resistor of about 47k between each lead and ground. This will act as a voltage divider, and might be an easier way to reduce the signal voltage.

You should be seeing signals of only a few millivolts - maybe 50mV maximum. If you're seeing voltages in the volt range (1V or higher), then you're an antenna, and you're picking up voltage from somewhere else! Also, you'll find that any televisions in your area will tend to induce voltages in you. Turn off the telly, or better yet, go into the back yard/garage and try there if that's possible.

The only other thing I can think of is if you're living under power lines. They will cause you all sorts of problems, at all sorts of frequencies.

As someone suggested, maybe if you post a schematic (circuit), it will help to pinpoint any unusual problems or potential danger points.

Given that you connect your probes to each temple and one in the middle, I'm surprised you didn't turn into Frankenstein! Did smoke come out of your ears? smiley

Let us know how you got on, it sounds an interesting project!
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