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4906  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Do you think my project is possible on: April 26, 2010, 11:08:35 am
When you say "60", the metronome will output 60 beats(in sound)

You do realize that the HM2007, when used in speaker-independent mode, has a vocabulary of only 10 words, right?

So - you wouldn't be able to say "60" (unless that is a common BPM?), but you could say "six-zero" (and anyone else could, as well).

The only problem here is that while you could get it to be speaker-independent for 10 words (numbers 0-9), you wouldn't have any "mark" or "command" words to tell it to "go" (you would probably have to use a timeout or something; but then again, you wouldn't have any way to tell it to "start", either).

The 40 word vocabulary of the HM2007 is only available for speaker-dependent use; if only one person -ever- will use this, and you don't mind re-training the metronome between users (or each user would have their own), then the system could potentially be more versatile, at the expense of needing to be trained before usage.

Maybe you should go for a hybrid approach; use those 10 speaker independent words for commands: "set beat", "play beat", etc - then have it listen for clapping for the beat via a separate system (which would be similar to a door knock detector) activated by the command spoken.

4907  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Connect to network via USB?? on: April 26, 2010, 12:47:11 am
Using a web server like apache on the pc would be one way.

Actually, the best way would be to set up a SLIP connection on the PC talking to the serial port the Arduino is on:

Fortunately, there's a library:

4908  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Analog Input on: April 25, 2010, 05:00:16 pm
Back when I went to HTI here in Phoenix, one of our projects was to create a photo-transistor array (8x8) that could be read by an Amiga 500 via its parallel port (we had to code up in C a program to read the data from the port); from what I (barely) remember, the way it was driven was via a circuit similar to what is seen implemented to drive an 8x8 LED matrix...

4909  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: ROV DC motors need some help on: April 23, 2010, 02:10:32 pm
[edit]I'm just trying the bootstrap the experiments here - the precision engineering comes later[/edit]

I suppose, but I can imagine the follow up question of "I can get it to turn both ways now, but I can't shut it off" - it would be easier to head that question off first.

I guess the initial "u" is silent, like the "c" in "rap music"

I know I have posted about this before; ROVs are underwater remote operated vehicle, UAVs and Unmanned Aerial Vehicles, and UGVs are Unmanned Ground Vehicles. This is just the way things are; do a search for "ROV", you'll find submarine vehicles galore (plus a few water surface craft; maybe these will be call UFVs or UBVs in the future?).

4910  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: ROV DC motors need some help on: April 23, 2010, 11:17:26 am
Groove, Zoomcat; based on your words/drawings - while those ideas will allow direction control of a motor (and in Zoomcat's case, limit switches to shut it off) - neither of these will work for the OP's application.

What's being built is an ROV (underwater remote operated vehicle), the up/down (and left/right) motors need a way to be turned off (and while Zoomcat's limit switches could work in a steering control or similar, they aren't much use for a prop thruster).

What is needed (if using relays) is an h-bridge constructed from 2 SPDT relays (each with their own transistor control), one for each motor. Alternatively (and better from an amperage point of view) would be to use 4 SPST relays, one for each leg of the h-bridge; and 4 transistors (and diodes, and everything else) - plus you would need to be careful not to set the wrong relays creating a direct-short...

Really, it would be better to (and cheaper), depending on the current requirements of the motors, of course - to buy some IC-based motor drivers (L298, etc) instead; depending on the source, it would only cost a few dollars per motor, whereas the relay method could cost much more than that.

Of course, if the current requirements are high, then using relays may be the cheapest method per motor; high-amperage pre-built motor drivers (greater than 5 to 10 amps) get expensive quickly, whereas relays are cheap.

The big disadvantage, though, of relay h-bridges (unless you have a beefy mosfet controlling the motor power input), is the inability of them to PWM speed control the motors - this applies whether the h-bridge is driving a low current or high current motor (though it can be done with a low current motor if a suitable transistor or mosfet of the proper size is used to control the motor power input, as mentioned; a large NPN or N-channel mosfet on the low side of the h-bridge and ground could work).

The OP's gonna need a bigger allowance to complete this project if he wants to use the Arduino in it!

4911  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Is this a good deal? on: April 19, 2010, 06:49:13 pm
i believe the low deck is called a breadboard.

I take it the "400" term means 400 tie-points...?

and yes, it's in US dollars.

If you were here in the US, then that wouldn't be so great a buy; does the $66.00 US include the shipping cost?

the thing is that they have to be able to ship to sweden.

Normally I would suggest buy the Arduino, then spend the rest of the money on some "grab bag" part kits from a surplus dealer, and pick up a cheap breadboard and wires off of Ebay.

Since you are in Sweden, though, where surplus is apparently outlawed, and there are shipping restrictions (for what reason?) - if that $66.00 is all-inclusive (parts and shipping), then it is probably your best deal - for your geographical area.

Elsewhere, maybe not so much.

That must be the tradeoff for universal health care and babes...


Hopefully I'll be old and senile (then again, I am already half way there - you decide which half!) before that happens here in the States; I don't think I could live if I didn't have electronic junk to scrounge up and play with...

4912  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Is this a good deal? on: April 19, 2010, 02:38:32 pm
What exactly is the second item?

Is $66 "US dollars" or some other currency?

I concur with Paul that if that is US dollars, that's a little high (depending on shipping).
4913  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: problem in sending values serailly on: April 20, 2010, 12:11:11 pm
Why not just send the ASCII byte - 0x00, 0x01, 0x02...0x0A, 0x0B, 0x0C...0xFD, 0xFE, 0xFF?

Those values (in hex) correspond to the values 0, 1, 2...10, 11, 12...253, 254, 255. Just output those characters to the port, and read in the values on the Arduino.

For example, say you wanted the number "65" for the Arduino; ASCII value 65 equals "A" - so send an "A" (66=B, and so on).

For the lower values, you may need to get tricky, depending on the value. For example, "0" is the null character, so in C you would send "\0" (IIRC). For "10", which is the linefeed character, hex 0x0A - you would send "\r". Depending on how you wrote your serial output interface on the PC side, you may be able to get away with sending the hex values directly.

As others have noted, there are plenty of examples on this, and there are plenty of libraries that deal with this issue if that works better for you and you have the leftover memory to include one. You already know you are getting ASCII values for characters you send; just expand on this knowledge (note - it is a good idea in your loop to look for start and end characters that signify the beginning and end of the transmission; that way, spurious characters won't likely cause an unwanted action to occur).

Good luck.

4914  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Need some advice on a Digital Potentiometer on: March 30, 2010, 04:07:52 pm
Oooh I never thought of that.  I'll have to check if there are any nearby..

I was just asking my wife last night if we knew anybody with a non-salt water pool; I was wanting to buy some HCl myself for the same purpose, but I didn't want to store 2 gallons worth (for pools, they typically come in a box with two 1 gallon jugs). I only want about 32 oz.

You can typically find the stuff anywhere pool stuff is sold; I know our local Albertsons carries it; Frys (groceries) carries it; Safeway has it too. You might also be able to find it in higher concentrations at a janitorial supply or hardware store as a concrete cleaner/etchant...

4915  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Need some advice on a Digital Potentiometer on: March 30, 2010, 12:22:00 pm

First off, I think you are selling yourself short; I really think you have the skills to pull this off, and you can read that tech sheet and such - just take your time, and don't get in a rush.

From what I can see on that sheet, it doesn't look too difficult to interface with. I would also bet that the code from the original example could be adapted (just serial comms in probably a slightly different format; I didn't look too closely at it, but it seemed workable).

I think if you take the time to compare things, you can get this to work out. From what I could see, there really didn't seem much to it (famous last words, I know).


The only other thing that concerns me, though, and once again, I didn't look hard into it, is whether the digital pot you are using will have the range needed (or if you can adjust it using a fixed resistor either in parallel or serial with the digital pot) for the LM317, as well as the current handling capability. If you can verify that, then it is simply a matter of hooking up the SPI interface and writing code to control it.

I would certain try to modify or add on to the original library, to expand it for others. If I were taking it on, actually, I would probably want to try to make the library more modular, to allow for the easy addition of future chipsets (at least in the same family). But that is just me. I certainly think you could get this to work with this digital pot.

I also noted that the chip you picked has multiple pots (2); you could use the other for variable current control in the future (not sure how that actually works, though - I've got little experience with power supply design).

If you can make this thing be a variable voltage controlled power supply, from something like 0-15VDC at 2-10 A output - I would love something like that for my bench for cheap (I've been pricing benchtop supplies, and such supplies are anything but inexpensive - not out of my price range, but I would love to find something cheaper).

4916  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Where to get larger pushbuttons? on: April 21, 2010, 11:24:42 am
Not sure if they'll have the size you need; but arcade machine controls come to mind:

They don't come cheap, though!

4917  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: working with multipel serial devices? on: April 19, 2010, 12:27:48 pm
To give you a possible answer, though - have you thought about RS-485?
4918  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...
4919  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).

4920  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!

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