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1306  Using Arduino / Project Guidance / Re: Help: arduino php mysql (electronic toll booth) on: February 01, 2013, 05:32:48 pm
This is wrong and will cause a 400 error:
Code:
client.print("GET try.php?code=");
Should be:
Code:
client.print("GET /try.php?code=");

Also, suggest you use HTTP/1.0 instead of HTTP/1.1. The latter will cause a "keepalive" request and does not close the connection after the request is complete.
1307  Using Arduino / Project Guidance / Re: torque sensor on a bike on: February 01, 2013, 11:00:58 am
http://keithhack.blogspot.ca/2013/01/v3power-meterthe-complete-how-to.html
1308  Using Arduino / Project Guidance / Re: Have robot, won't travel? on: February 01, 2013, 04:10:54 am
If I'm reading the datasheet correctly, the L298P will drop the voltage to the motors between 1.8V to 3.2V at 1A of current.

Use more batteries.
1309  Using Arduino / Project Guidance / Re: Serial internet connection, HTTP GET request on: February 01, 2013, 03:56:59 am
You will need some sort of intermediary program running on the computer and listening to the serial commands from the Arduino.

The http://playground.arduino.cc/Main/InterfacingWithSoftware page lists a few ready to go programs that might do what you need or it lists a number of examples using various programming languages if you need to write a custom application.
1310  Using Arduino / Project Guidance / Re: Help with guiding a tractor on: February 01, 2013, 03:04:59 am
The low budget approach would be to use a "foam marker". You just need an air compressor, a small fuel tank, and some soapy water. The compressor bubbles air into the soapy mixture and forces blobs of foam out that you use as a reference to see where you've been.

ROFL!!!!!!!!!!!
i have to say this made my night!!!

I was being serious; this is the standard way that it is done professionally, albeit with more complex foam generating equipment.



I mean, that's no toy tractor, and at the end of the booms those are the foam droppers.
1311  Using Arduino / Sensors / Re: Stuck on calibration for (LSM303) Accelerometer on: January 31, 2013, 07:52:26 pm
Your X readings are coming back -12, -24, -84, and you're trying to map that from the range 1032 to 1064 (Xmin to Xmax). Those numbers aren't inside that range. I don't know how map() will react to that.
1312  Development / Other Hardware Development / Re: where to buy 2560 Mega IC on: January 31, 2013, 07:48:16 pm
You can try octopart.com or findchips.com; they have European sites in their listings. Minimally it gives you an idea on pricing.

http://octopart.com/atmega2560-16au-atmel-477241
1313  Using Arduino / Motors, Mechanics, and Power / Re: Pnuematic Pump Suggestion on: January 31, 2013, 06:45:47 pm
An aquarium pump would not provide sufficient PSI; you'd need to go to something like a car tire inflator.

If you need an inexpensive air tank you can build one from PVC pipe. Just keep the pressure low and don't go over 40 PSI.
1314  Using Arduino / Sensors / Re: Stuck on calibration for (LSM303) Accelerometer on: January 31, 2013, 06:38:56 pm
This is not correct. lms.accelData.x (or y or z) is only updated after calls to lsm.read(). If you .read() it once then look at it 100 times it will be the same value.

Code:
 for (int i=0; i<100; i++)
  {
    XSum += ((int)lsm.accelData.x);
    //YSum += analogRead(YPin);
    //ZSum += analogRead(ZPin);
  }
  
  lsm.read();

Not sure why you're getting a crazy value here though:
Code:
Serial.print(map(XSum/100, XMin, XMax, -2000, 2000));
1315  Using Arduino / Project Guidance / Re: Help with guiding a tractor on: January 31, 2013, 10:42:41 am
The low budget approach would be to use a "foam marker". You just need an air compressor, a small fuel tank, and some soapy water. The compressor bubbles air into the soapy mixture and forces blobs of foam out that you use as a reference to see where you've been.
1316  Topics / Science and Measurement / Re: Your Idea of My Final Project? on: January 31, 2013, 12:43:36 am
Is your intended scheme going to be:

Computer -> Arduino -> Xbee (or other wireless device)-> Xbee -> Arduino -> Ardupilot?

For the Computer to Arduino part, see http://playground.arduino.cc/Main/InterfacingWithSoftware. Covers pretty much every programming language you can think of.
For the Arduino to Xbee to Xbee  to Arduino part, see http://www.billporter.info/2011/05/30/easytransfer-arduino-library/. This library really simplifies communicating between Arduinos over serial, and since Xbees have a serial interface it kinda makes it a done deal. There are a lot of non-Xbee devices that have serial interfaces so an Xbee specifically is not required, but I'll leave it to your discretion as to what might work better. I do know that Xbees are frequently used with RC planes for telemetry so they're kinda tried and true there.
For the Arduino to Ardupilot part, see http://arduino.cc/en/Reference/Servo. This would let you send commands to the Ardupilot using the same method that an RC receiver would.
1317  Community / Bar Sport / Re: USPS out to kill hobby shipping on: January 31, 2013, 12:10:55 am
Their pension costs are out of control. That's what's killing them.

The USPS pays into the FERS (Federal Employee Retirement System) like all federal agencies and USPS employees will receive retirement benefits identical to all other federal employees (*some exceptions, of course). Unlike other federal agencies, however, they're being forced to pay in at a higher rate, or more generally they're being required to generate a surplus in their retirement fund because the OPM (Office of Personnel Management, which manages FERS) has determined that the USPS is at risk of collapsing.

I also agree with cr0sh; if you dismantle the USPS it will just be replaced by other services (FedEx, UPS, etc.) at a higher cost.
1318  Topics / Science and Measurement / Re: Beginner with Chicken Project - Willing to pay for help on: January 30, 2013, 11:23:26 pm
I don't think RFID would work here; it works for a cat because a cat holds its head low and is predictable as to where the dangling RFID tag will be when it walks up to the door. The RFID reader you have linked (well, the non-discontinued version) states a 7cm sensing distance. I have no idea how you'd leash an RFID tag onto a chicken to get a predictable 7cm position and reading.

I'd suggest a simpler method would be to use some sort of light beam across the nesting area inside the nesting box; when the chicken blocks the beam it's in the box. An infrared LED and infrared phototransistor can be wired up to do this.

You might want to look into the Seeeduino Stalker which includes an SD card socket and real time clock right on the board ($39). It also provides a solar panel input and LiPo battery input so, if you keep your current consumption low, you might not even need to run power out to your house.
1319  Using Arduino / Sensors / Re: K type thermocouple on: January 28, 2013, 06:40:28 pm
Take a look at the AD595 datasheet, see what level of input it is expecting from the thermocouple.
The '328P can take in 1.1V/1024 as the lowest reading, about 1mV. Probably not reliably, will need a couple of mV for a reliable reading.

Looks like type K's are around 4mV per 100C. It should work.

http://srdata.nist.gov/its90/download/type_k.tab

1320  Using Arduino / Motors, Mechanics, and Power / Re: Unsure which motor controller to use on: January 28, 2013, 01:14:02 pm
The motor only draws as much current as it needs. The more load it is under the more current it will draw, up to the point where you stop the motor completely where it draws the most current -- its stall current.

"Having 10A available" does not mean it will ever draw 10A, just as when you screw in a light bulb it never takes down the local power plant. The internal resistance of the motor, created from incredibly long windings of thin wire, limits how much current it will take.

I'd respectfully disagree with johnwasser on the MC33926 board. The docs state that the chips are rated 5A continuous if you add heatsinks or other cooling. It also has thermal shutdown to prevent it from overheating. If you're just running around on smooth/flat surfaces I wouldn't expect any issue.
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