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811  Using Arduino / Project Guidance / Re: Temperature Sensing on a Farm on: May 27, 2011, 04:01:04 pm
If one of them breaks, the others route around the broken one.  It's a way of the network taking care of itself.  Really nice in a situation where you need to keep things working, just add a couple of strategic devices and keep a spare on hand that you can bring online when you need it.  This way a temperature sensor also works as a router to carry the data from some more remote sensor that in turn acts as a router.
812  Using Arduino / Networking, Protocols, and Devices / Re: Help with xbee hardware on: May 27, 2011, 03:56:32 pm
Here's what I did.  I bought a few of the adafruit boards and then went to digikey and bought the buffer chip, power supply, capacitors and such.  I populate the board on what I plan on doing with it.  If I have 3v available, I don't need a power supply, if I'm using 3V logic I don't need the buffer.  See the trick?  In one instance I didn't need the board at all.

However, I did need a minimum of one usb adapter to the laptop and one fully populated adafruit board with FTDI cable on hand as I got into the project.  You can get by with the minimum of an arduino and a FTDI with the adafruit board because the arduino can be used to connect to the XBee.

The reason I have the USB adapter is to monitor the working XBees in action.  If I want to see what is going on, I plug in the usb adapter and just watch things happen.  If a person only has two of them watching one end perform is good enough, with more of them you'll want to see the various interactions and occasionally put something out to simulate something.
813  Using Arduino / Networking, Protocols, and Devices / Re: Help with xbee hardware on: May 27, 2011, 01:26:02 am
So far I have six XBees running around the house and never bought a shield.  I do have several adafruit XBee adapters and in one case I wired the XBee directly to the arduino.  You CAN hook an XBee directly to the arduino by using the 3.3V supply, ground and serial pins.  I have a device running just this way because I ran out of adapters once.  To secure them to something I use two sided tape, simple and cheap.  If you want to see the various items I've got running take a lock at my blog at under the XBee tab at the top.  I even stuck one to the side of a wall wart as a temperature sensor.

You DO NOT need a complicated setup to get these to work.  I do recommend that you have two ways to connect the XBees to your computer so that you can run two of them at a time.  It's much easier to set them up and get them working if you can run two at once and play with the configuration.  Also, I don't always use arduino pins 0 and 1 to communicate with the XBees.  I use newsoftserial version 10C and put the XBee on a couple of digital pins.  This way I don't have to remember to unplug it to download software to the Arduino. 
814  Using Arduino / Networking, Protocols, and Devices / Re: What connection? on: May 25, 2011, 10:42:29 am
cantore's technique is exactly what I use as well.  If you want to send several values just separate each of them with a comma from the last one and then the server can parse them out.
815  Community / Exhibition / Gallery / Re: Arduino Controlled Dishwasher on: May 25, 2011, 12:11:17 am
Holy Cow, that is so cool.  Interesting how insurmountable problems somehow get resolved once one's mindset changes.  I am very impressed at your efforts on this.  Now, the real challenge begins, how the heck are you going to make this look good on the front of the dishwasher?

Be sure to come back and post again when you get it finished.  I'm going to steal ideas.
816  Using Arduino / Networking, Protocols, and Devices / Re: What connection? on: May 24, 2011, 11:49:01 pm
This may not be the best way to do it but I convert the ints, floats, whatever to ascii and send it as text.  This has the incredible advantage of being readable when debugging.  I usually format the data into comma separated values (CSV) and the do a get with the values.  Over the wire it would look like "Device1,128,36.4,12" and the receiving end would parse out the values it wanted.

On a pc you can do a split() to have the data values separated, on the arduino there are other techniques that you can use.

Does any of this make sense?
817  Using Arduino / Project Guidance / Re: Measuring Mains Voltage on: May 24, 2011, 11:10:25 pm
Just a quick (hopefully) note on the other things that came out of this discussion:

Lefty you're right (pun totally intended) I have seen young people on this forum and others that I wouldn't recommend messing around with a 5V supply, much less something that can overcome skin resistance.  My problem was only with preaching that it was unsafe without an example or instance or anything.  That's what I ran into when I was reading a thousand or so posts on this kind of thing around the web.  Just, "Don't do it, it'll put your eye out" kind of statements.  I guess the "kid with the BB gun" in me can't accept that.

Your example of having to share a ground with the AC neutral is a good one as was Jack's of a hot chassis.  These are both problems that can be overcome relatively simply, but if one is going to ever share such a thing....beware of the uninformed.  The floating (voltage wise) arduino is another concern because someone will probably grab the arduino and the faucet at the same time; especially in a stainless steel, grounded refrigerator.  Sigh.

So, as I mentioned before, I'll bite the bullet and get a transformer, darn it.

In answer to some of the other questions.  Yes, you sample the instantaneous voltages over a power cycle as well as the current (going to use a hall device this time) and then integrate to get the various values.  You can measure the power factor and frequency of the incoming power to see what happens when you turn on the plasma cutter to cut a kink out of the tractor's fender.  I already do this for both phases of my home power using 200A current transformers wrapped around the mains input inside the circuit box (see, I'm not afraid of the voltage).  The calculations sound complex, but actually aren't bad at all.  My reading on an instantaneous basis rival the power company's expensive meters.  Yes, they've been out here explaining how they measure the power and comparing their results to mine.    Over time, their temperature compensation is better and my sums (of the readings) drifts from the KWH they record and I pay for, but not by enough to worry about. 

I've had county inspectors looking at it, people from the power company looking at how I did it and even energy conservation experts from a swimming pool company comment on it.  It was a really fun project that is ongoing (forever) and now I want to start applying it to smaller appliances.  For example, I have separate refrigerator and freezer.  Individually, they don't use much power and represent a minor expense, however with demand metering, if they both kick on at the same time, it drives demand usage up and I pay a ton for the small fraction of time that they operate together.  Hence, this project.  I describe this in horrifying detail on my web site at  I also have the various schematics and code that is running most of the devices I've incorporated into this project.  So, if you want to do something similar, grab anything you want and go for it.  Around my house, the current power usage is as easy to find as the time of day.
818  Using Arduino / Project Guidance / Re: Measuring Mains Voltage on: May 24, 2011, 09:37:18 pm
That's it Jack, you nailed it.  If I hook directly to the mains for my circuit, it will be fine until I turn the plug over.  Now, the hot side is in a different place and can cause some real problems. 

That's exactly what I was looking for and no one ever mentions.  Sure I could put a polarized plug with a ground pin on it to keep myself out of trouble, but if someone copied my circuit and didn't.....boom.  It isn't that its unsafe to do this, it's like you said, someone else won't take the care that I (hopefully) did in setting it up or modifying it.  There are ways of avoiding the problems you pointed out (excepting lawyers), but it's hard to make something foolproof; fools are too resourceful. 

Thank you.  I guess I'll go look for a really small power transformer that I can use to sample voltage and leverage it as a power supply for the rest of the circuitry.  The hall effect device will still be in the mains circuit, but it's optoisolated, doesn't care which leg it's in and UL rated to 3KV.
819  Using Arduino / Networking, Protocols, and Devices / Re: 'GETrequest' does not name a type on: May 24, 2011, 09:15:05 pm
Found it!  You probably have the correct library.  There is a configuration parameter in the file apps-conf.h and you have to select WiServer for this.  The part you want is up at the top and looks like this:

//Here we include the header file for the application(s) we use in our project.
//#define APP_SOCKAPP
//#define APP_UDPAPP
//#define APP_WISERVER

comment out the APP_WEBSERVER and uncomment APP_WISERVER, then you should be fine.  I did that so long ago that I forgot about it.
820  Using Arduino / Networking, Protocols, and Devices / Re: 'GETrequest' does not name a type on: May 24, 2011, 08:12:26 pm
Just tried SimpleClient and it compiled correctly.  You probably already did this but, did you restart the IDE after putting the library in place?  The development environment has to be shut down and started again so it will notice that there is a new library in place.  I've made this mistake a couple of times and gotten the same kind of message.  Another possibility is that the library you picked up has a problem, you may need to hunt down a later one; maybe at the asynclabs web site.  I got mine there.
821  Using Arduino / Project Guidance / Re: Measuring Mains Voltage on: May 24, 2011, 08:04:04 pm
It is intrinsically unsafe connect direct to the power mains.  Anyone who comes here asking how to do it is assumed to be not experienced enough to recommend the practice to (at the risk of encouraging dangerous behavior.)

I've seen this over and over, the question is:  why?  I just don't accept that anything is intrinsically unsafe that is done by device after device that you can get in the marketplace.  Every single extension cord is connected to the mains.  Every X10 or insteon device is hooked to the mains.  Every wall wart is connected to the mains.  We mess with mains voltage every time we replace a socket on a table lamp.  Or, for that matter every time we change a light bulb.  The much touted kill a watt is connected to the mains.  This kind of thing just doesn't hold water if you actually examine the statement.  As for encouraging dangerous behaviour, don't encourage me, just tell me why it's dangerous to use a voltage divider.

Also, don't make assumptions about my experience level or the experience level of anyone else that posts. Assumptions about people's experience is not nice, ask if you wonder about it.

The safest way to measure power mains voltage is to simply use an inexpensive (perhaps even free) AC wall wart and simply rectify and filter the voltage. The DC voltage out of the circuit will be directly proportional to the RMS power mains voltage. And there are various ways of measuring current also. There are Hall-effect devices for measuring DC (or isolated AC), and there are clip-on current transformers, etc.

I don't want the rectified and filtered voltage stepped down by a transformer to what people assume is a 'safe' voltage.  I want the instantaneous voltage taken at many points in the cycle both above and below the zero reference; a filter would destroy that data.  I would rather not have the phase offset caused by the inductive load of a transformer, this can be calibrated away, but avoiding it entirely would be better.  I know about the hall effect devices and plan on using something like to get the instantaneous current.  That device will hook directly in line with wall power. 

I'm not at all afraid of 110, 220, 440 etc.  I have a healthy respect for the current capability and the possibility of higher voltages causing problems that are somewhat unexpected, but I just don't buy that it's intrinsically unsafe.  It might be less safe, but one must take care with anything that one does.  Heck I've had 12V blow a hole in a 440 stainless adjustable wrench when I didn't pay enough attention an shorted a car battery; that's a voltage everyone on this forum has used.

So, now that we've both got that off our chests, what's wrong with a voltage divider?
822  Using Arduino / Project Guidance / Re: Temperature Sensing on a Farm on: May 24, 2011, 07:17:30 pm
I'm not sure if this is what you need, but I made a really simple temperature sensor hooked to an XBee for measuring outdoor temperature.  I plug it into an outdoor outlet and just let it run.  Took two 10K resistors, a wall wart, and an XBee and of course, a wall plug.  Since the XBees can forward for each other, you could easily get by without buying the expensive pro models.  Last time I looked the pro modules cost 3x the lower powered ones and outside, you can get pretty good range.  The problems with transmission distance come when there are walls involved, especially outside walls that have some kind of metal lathe.  If you want to see my little device, go to my web site at and look behind the tab "world of XBee"  a picture of it is at the bottom of the page.
823  Using Arduino / Networking, Protocols, and Devices / Re: 'GETrequest' does not name a type on: May 24, 2011, 06:54:40 pm
I just compiled SimpleServer from the examples under IDE version 21 with no problem.  What are you trying to compile?
824  Using Arduino / Networking, Protocols, and Devices / Re: Xbee series 2 Co-ord & End 2 way communication on: May 24, 2011, 06:20:48 pm
Since you're using the AT command configuration, there's only a few things you need to do.  Take a look at my site behind the tab that says "World of XBees" and I describe the things that can cause you trouble getting them to talk.  It's not really hard.  Just pick a pan id, note the addresses of the XBees and start configuring them.  The easiest way to get them talking is to have both of them plugged into the same computer.  If you have the hardware to do this I highly recommend it.  You would need a couple of devices of some type to connect them to the computer and open two instances of XCTU to connect to the XBees and just configure and test away until you understand their interaction.

The very first time I did this I used two arduinos with the XBees connected to them and each arduino was USB connected to a laptop.  Lots of hardware, but it's what I had at the time.   Now, when I experiment I have one XBee to USB adapter and an Adafruit adapter plugged to an FTDI cable.  It's just too convenient to be able to change and test each XBee and immediately see the results.

In direct answer to your question ATDH and ATDL are necessary, but you may have to do a couple of other things as well.

Google is your friend when you're trying this.
825  Using Arduino / Project Guidance / Re: Measuring Mains Voltage on: May 24, 2011, 06:11:04 pm
Thanks for the description.  I've worked with 120 @ 60 a lot, take a look at the power monitor I built it's behind the tab about how I monitor power.  What I'm looking for is why there is so much bad press about messing with the mains.  If you open an X10 device, it is hooked directly to the wall plug and these things don't seem to kill anybody.

See, a voltage divider would directly follow the power levels and I could sample it around 3K times a second to get the instantaneous levels.  There's no reactance from a transformer or capacitor to deal with so no phase delays to worry about in the calculations.  It just seems like the perfect solution, but there is post after post on the web telling people not to do this.  I just can't see why not.

The solution of turning the thing off is actually a darn good one, but I've got an arduino.....I just have to get it involved somehow.  The idea of monitoring the freezer to be sure the temp is low enough, controlling when it uses power, maybe tracking the door to see if someone is trying to steal a steak is pretty darn appealing.
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