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5596  Using Arduino / General Electronics / Re: Arduino power(ing) issue on: May 07, 2012, 08:48:14 am
The USB cable provides a fairly good ground that a battery won't.  Perhaps some of your inputs are floating and you are getting more noise without the Ground.
5597  Using Arduino / General Electronics / Re: Vin and atmega8u2 on: May 07, 2012, 08:43:24 am
I use Arduino Uno.

Which model?  The R3 schematic shows that USBVCC is used for the +5V supply if half the VIN supply is less than 3.3V

Are you using a USB cable for serial I/O?  If so, why isn't the host system providing 5V to USBVCC through the USB cable?
5598  Using Arduino / General Electronics / Re: Arduino/stepper/servos/switch - please advice if circuit is correct. on: May 07, 2012, 08:23:38 am
Looks good to me.
5599  Using Arduino / Microcontrollers / Re: How to put Arduino Mega 2560 in dfu mode? on: May 07, 2012, 08:20:47 am
http://arduino.cc/en/Hacking/DFUProgramming8U2
5600  Using Arduino / Networking, Protocols, and Devices / Re: Unable to connect ethernet shield to internet on: May 07, 2012, 08:06:11 am
Perhaps File->Examples->Ethernet->TwitterClient would be a good starting point.
5601  Using Arduino / Networking, Protocols, and Devices / Re: Unable to connect ethernet shield to internet on: May 06, 2012, 10:24:13 pm
If you are using Arduino 1.0 then the arguments to Ethernet.begin() have changed.  Your best bet is to pass only the MAC address and let DHCP assign everything else.
5602  General Category / General Discussion / Re: New guy here on: May 06, 2012, 05:18:06 pm
You will need a network connection.  That would be Ethernet if your washing machine is near a router or a WiFi shield if you have a home wireless network,

Second step is to figure out how to send email from an Arduino.  Someone has probably done that before so you should try some web searches.

Third step is figuring out how the Arduino is going to detect the end of a cycle.  Since the washing machine time is probably switching house current you will probably want some kind of isolation.  Perhaps an opto-coupler or opto-isolator.
5603  Using Arduino / Project Guidance / Re: Very Small Arduino on: May 06, 2012, 05:11:19 pm
So why would one want a different ground plane for analog and digital?

To keep the switching noise associated with digital circuitry out of the analog conversion hardware and thus reduce noise in the inputs.
5604  Using Arduino / Motors, Mechanics, and Power / Re: motor with arduino! on: May 06, 2012, 05:06:36 pm
That won't work well because "HIGH" is defined as 1.  You'd be switching between OFF (0) and 1/256th on (1) which is almost the same thing.  If you want on-off control use digitalWrite() with LOW for OFF and HIGH for ON or use analogWrite() with 0 for OFF and 255 for ON.
5605  Using Arduino / Audio / Re: Arduino 8ohm Small Piezo Speaker: Can you play two Tones at once? Like chords? on: May 06, 2012, 12:09:15 pm
This third-party Tone library can play simultaneous square waves on multiple pins:

http://code.google.com/p/rogue-code/wiki/ToneLibraryDocumentation

You can connect resistors between the multiple pins and a single speaker to get all tones out of one speaker.
5606  Using Arduino / Programming Questions / Re: Port Manipulation question on: May 06, 2012, 11:57:51 am
I've been using the digitalWriteFast, which somehow is faster, smaller, and easier than port manipulation.
http://arduino.cc/forum/index.php/topic,93737.0.html

It's faster and smaller only if your pin numbers are compile-time constants.  If your pin number is a variable then it will be the same speed as a regular digitalWrite().
5607  Using Arduino / Programming Questions / Re: Branch To Subroutine on: May 06, 2012, 11:51:40 am
On a standard Arduino pin 0 will not work as an interrupt, only pin 2 and 3. So your interrupt is never activated, never setting resetP to 1, thus never satisfying the if to call your subroutine.

Interrupt 0 is on pin 2.  attachInterrupt() uses the interrupt number, not the pin number.

The code uses Serial3 so it's running on an Arduino Mega of some kind.  That means interrupts 0-5 are available from pins 2, 3, 21, 20, 19, and 18 respectively.
5608  Using Arduino / General Electronics / Re: PIR Sensor Trouble on: May 06, 2012, 11:40:15 am
What is that black thing plugged in next to the PIR connector?

As near as I can tell:

 The Black wire is Power and goes to Arduino +5.
 The Brown (center) wire is Ground and goes to Arduino Ground.
 The Red wire is the signal.  It connects to an Arduino digital input pin.  It needs a pull-up resistor but you can use the internal one like this:
Code:
const int PIRpin = 3;  // Or whatever pin you have it connected to
void setup() {
    pinMode(PIRpin, INPUT);
    digitalWrite(PIRpin, HIGH);  // Enable the internal pull-up resistor
}
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5609  Using Arduino / LEDs and Multiplexing / Re: Driving high power LED on: May 06, 2012, 11:20:55 am
The 22 Ohm resistors are in that circuit to limit current.  If they are sized correctly they will prevent over-current on the LED.  A constant-current driver will do roughly the same thing and provide better current control if the input voltage might vary (like in a car power system where "12V" can go over 14V.
5610  Using Arduino / Motors, Mechanics, and Power / Re: motor with arduino! on: May 06, 2012, 11:13:23 am
If the motor draws more than about 30 mA (and it probably does) you will need a transistor to switch the power:

http://bildr.org/2011/03/high-power-control-with-arduino-and-tip120/

If you want to vary speed with software, use a PWM output and "analogWrite()".

If you want to reverse direction you will need an H-bridge.  Look for a "motor shield".
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