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3676  Using Arduino / Programming Questions / Re: help needed for changing the speed of a continuous servo on: August 05, 2013, 05:39:38 am
You cannot control the speed per-se on a servo modified for continous rotation.

Yes, you can. For each server there will be a pulse length corresponding to the neutral position. When you send this pulse length the servo will not move. Altering the pulse length either side of that value will cause the servo to move forward or backwards, and the further away you go from that neutral value the greater the speed (until you reach the servo's maximum speed).
3677  Using Arduino / Programming Questions / Re: What functions interfere with EEPROM read/write? on: August 05, 2013, 05:35:38 am
Suggest you post a minimal sketch which demonstrates the problem, for example by writing a sequence of hard-coded values to the EEPROM and displaying the values read back. It may be a hardware problem, but it may simply be a problem with your code.
3678  Using Arduino / Programming Questions / Re: Usb to serial diy converter on: August 04, 2013, 05:58:26 pm
Anything with a d-sub connector is probably using RS232 signaling and would need to be converted to TTL serial signaling before it is safe to connect to your Arduino.

There are readily available and inexpensive USB-to-TTL-serial converters which do exactly what you need - most hobby sites that offer Arduino hardware and clones will offer something suitable, and they only cost a few bucks. The only gotcha is to ensure that the TTL voltage level of the converter matches the voltage of your board i.e. 3.3V or 5V.

ETA: or in other words, what Majenko said.
3679  Using Arduino / Project Guidance / Re: Whistle detection-pressure cooker on: August 04, 2013, 05:53:18 pm
I don't know how much of the project you're describing is specified for you and how much constitutes part of the solution that you have designed.

If the person specifying this is intending that it does something that could credibly be useful to a cook, I'd suggest that monitoring the temperature would be the most useful thing to do. Zoomcat's idea of using an IR thermometer might be your best bet, although in my experience pressure cookers tend to be shiny metal and that's not a good target for an IR thermometer. So it would be quite hard to do in general, but if you can control the test conditions then it should be possible to get something to work. If you're willing to put something in contact with the lid of the cooker then things get much easier, and you also have the possibility of implementing an over-temperature alarm (aka your pressure cooker has run out of water and is about to be destroyed).
3680  Using Arduino / Project Guidance / Re: Ethernet with SD card Shield - Compiling larger scripts. on: August 04, 2013, 05:46:05 pm
Well, I know you can load html pages on the SD card support for the Arduino, but what I'm saying is, if I need to compile anything directly such as giving the Arduino SSH or FTP support so I can tunnel in and move what I need to do.

I do a lot of embedded work professionally with PLC's and SCADA networks.

What I'm wanting to know is if I can compile something on the SD card if I were to use it as its ROM, so I could essentially compile and load an embedded linux kernel, or does the ethernet shield contain the a piggy-back processor that takes care of HTML instructions and the sort?

No, none of that makes any sense at all in the context of an Arduino. You can't compile any new Arduino features on the Arduino, and it's a few orders of magnitude short of being able to do anything with or to a Linux kernel. I don't know what HTML "instructions" you're thinking of, but the Ethernet shield has no knowledge of HTML, HTTP or anything of that sort - it just handles the transport layer and the protocol layers below that. The Arduino is a microcontroller, not a computer. If you want an embedded computer, you should be looking at a RPi or one of the other embedded computer platforms.
3681  Using Arduino / Programming Questions / Re: Serial Proxy that runs on a Arduino. Does it exist already? on: August 04, 2013, 06:56:34 am
If you're dealing with a CNC solution this implies a considerable investment of time and money - it seems odd to me that a few bucks difference in the cost of a different Arduino model would be a factor. If this is to be a product, it seems odd to me that you'd be wanting to use a standard Arduino at all.
3682  Using Arduino / Programming Questions / Re: How do I get an Arduino to initiate a UDP session? on: August 04, 2013, 06:53:04 am
There is no such thing as a UDP "session".

On the network side, that's true. But on the API side some of the semantics of a session do apply, for example in Posix you can bind a datagram socket to an address. While it doesn't establish a transport connection, it establishes a state within the client that has a similar effect at the API level.
3683  Using Arduino / Project Guidance / Re: Detecting lean angle on a motorcycle on: August 04, 2013, 06:47:12 am

Isn't that why bikers have knees?
3684  Using Arduino / Project Guidance / Re: Indoor tracking device on: August 04, 2013, 06:44:06 am
If there are people around the machines you want to track then one option is to install a siren which can be triggered remotely. If you're near by, you may be able to hear it directly. If you aren't, there may be other people nearby who can hear it and contact you to turn that damned noise off. Perhaps you could combine that with some sort of intercom mounted on the vehicle which people could use to contact you. If it worked, this might have a knock-on effect that people would be reluctant to have these machines left in their work area because of the nuisance factor when the siren goes off. That might be a good thing.
3685  Using Arduino / Project Guidance / Re: Ver...y long range communication on: August 04, 2013, 06:35:59 am
You may be overstating the requirements. Do you really need a wireless connection over 200 miles range? I can't see why you would need that unless your woodlands were 200 miles across, which seems unlikely.

Depending what your true requirements are, it may be that you can get away with a wireless connection with a much shorter range to a base station which has internet or phone connectivity (wired/wireless). It would be much easier to achieve this from a fixed base station than from a mobile device because you can use directional antenna to increase the wireless range, even if you can't manage to set up a wired connection. Depending on the size of antenna you're able to use at a base station and the area you need to cover, you may need multiple base stations. However you achieve it, once you have got a path back to a land line or cell tower, the rest is easy.
3686  Using Arduino / Project Guidance / Re: Whistle detection-pressure cooker on: August 04, 2013, 06:27:30 am
It may be that cooking is done differently where you are, but here in the UK when using a pressure cooker (whistling or otherwise) the number of times the pressure cooker "lets off steam" while cooking is irrelevant - once it has built up pressure it will vent any excess pressure as needed, just as a simmering pan produces steam. What is important is how long the contents have been up to temperature, not how many times a valve let off steam along the way.
3687  Using Arduino / Project Guidance / Re: Ethernet with SD card Shield - Compiling larger scripts. on: August 04, 2013, 06:22:06 am
compile scripts to or at least compile a smaller script that can point to the SD card to do the rest

You need to explain what you mean here. My best guess is that you want the web server to be able to serve out javascript files, style sheets, HTML documents and so on that are stored on the SD card. That's certainly feasible and not hard to get working. You would just need to work out the document name that was being requested, map that to a file name on the SD card, read the content of that file and write it out as an HTTP response.

What would be harder is dealing with the many options that HTTP supports for encoding, authentication, and all that other stuff that modern web sites use as a matter of course. You can make a functional web server on an Arduino, but making one that works as well as a modern PC-hosted web site is much harder. For one thing, the Arduino is very slow and extremely limited in the number of connections it can support.

If you want to use a fully featured web site as a front end for your Arduino then IMO you would be better off setting up an external web site that presents the front end, and have that communicate with the back-end Arduino server via a web service, or a serial interface, or any other mechanism you like. It will be much quicker and easier to develop, and it will work better and more reliably.

There's nothing stopping you from trying to implement something similar entirely on the Arduino but it will take a lot more effort and never work as well.
3688  Using Arduino / Programming Questions / Re: Number of digits to print on: August 03, 2013, 05:23:52 pm
Even better safety would be to use snprintf instead of sprintf, which will limit the number of characters it can try and put into the resultant string (snprintf(temp, 5, "%04d", A)smiley-wink

Even better would be to have the size argument be the actual size of the array, and not a hard-coded value that may or may not be correct.
3689  Using Arduino / Project Guidance / Re: Detecting lean angle on a motorcycle on: August 03, 2013, 05:17:02 pm
You cannot measure the lean angle with respect to gravity by measuring the distance to the road, since it's also banked.

Agree with your assessment of the physics, but if you're dealing with typical roads then in my experience local roads are usually not banked significantly and I suspect that it might be possible to get some indication of lean angle.

I can't think why that would be a useful thing to do, though.
3690  Using Arduino / Project Guidance / Re: help on: August 03, 2013, 05:13:38 pm
I think requiring the flow to be constant might be a problem, but if it's sufficient for it to be within some limits that you will set then everything else seems feasible.

The way I'd approach this is to have a variable holding the value of millis() last time the flow was seen to be outside the required limits. Use the technique demonstrated in the blink without delay example sketch to find how long ago that value was updated and hence whether the flow condition has been met for long enough to turn the LED on.

I guess you would also want to turn the LED off as soon as the flow was seen to be outside the required limits.
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