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1  Using Arduino / Project Guidance / Re: Data logging to a SD card. on: September 21, 2012, 04:29:18 pm
Quote
And what protocol is used to read and write from and to a SD card

There's a few libraries out there that support SD cards. There's one that comes pre-loaded with the IDE. Have a look on http://code.google.com/p/sdfatlib/ too; it covers communication with FAT32 and FAT16 cards.
2  Using Arduino / Project Guidance / Re: Motion & Light Activated Night-light (lights up if it's dark & there is motion) on: January 07, 2012, 03:21:15 pm
It's hard to see from the schematic, but it looks like you wired up the photoresistor wrong. It should form a potential divider:

Quote
                                     ->  ->
+ ------\/\/\/\--------------\/\/\/\/\/\/-------------| 0V
                            |
                            |
                      analog pin
By the looks of it, you missed out the 0V connection.

http://www.techitoutuk.com/knowledge/electronics/buildingblocks/potentialdividers/index.html

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3  Using Arduino / Installation & Troubleshooting / Re: What is arduino Uno's ADC input Current Min and Max? on: January 07, 2012, 12:36:44 pm
The inputs all have a very high resistance, so it will only draw a very small current. In order to draw more current, it must be at a higher voltage. Anything above 5V and it will be damaged.

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4  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet Shield on: January 04, 2012, 04:49:44 pm
Quote
The shield must be assigned a MAC address and a fixed IP address using the Ethernet.begin() function. A MAC address is a globally unique identifier for a particular device. Current Ethernet shields come with a sticker indicating the MAC address you should use with them. For older shields without a dedicated MAC address, inventing a random one should work, but don't use the same one for multiple boards.

Yes, inventing a random mac address should work fine!


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5  Development / Suggestions for the Arduino Project / Re: Arduino on ARM on: January 02, 2012, 07:54:29 am
I saw the Raspberry Pis yesterday, and I'm wanting one too! They're selling no9 and 10 on ebay at the minute, but they were >£1000, so I'll wait for them to start being produced...
They certainly sound exciting!

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6  Development / Suggestions for the Arduino Project / Re: Arduino on ARM on: January 01, 2012, 01:35:17 pm
Quote
How long is it likely to be until support is released for the ARM processors
The arduino DUE is coming out soon, and that has a 92MHz ARM processor on it, so the answer is not very long! There are several topics on it already, one of which can be found here: http://arduino.cc/forum/index.php/topic,85177.0.html.

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7  Using Arduino / Project Guidance / Re: Simplest way of timekeeping? on: December 31, 2011, 06:51:23 pm
If you can find an atomic clock decoder cheaply, I'd definately buy it smiley-grin . Or, you could buy a GPS module and extract the time (atomic clock accuracy) from that. On the other hand, you could do what I did and buy a DS1307 IC or module of eBay, or somewhere else, download a library for it and use that. It is easy to do, and gives decent accuracy.

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8  Using Arduino / General Electronics / Re: Grounding Multiple LEDs on: December 26, 2011, 05:59:56 pm
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Is it okay to connect all three of the LED's cathodes to a single wire, going into a single ground pin, or will I have to make use of three ground pins?
Yes, connect the three cathodes together and use one wire to ground. All the arduino's ground pins are connected to one Gnd connection of the power supply, so it makes no difference how many wires it goes through to get there.

Quote
and place a 1kΩ resistor between each LEDs anode and its assigned output pin
Good to see you remembered the resistors! If the LEDs are too dim, try a 330 ohm resistor.

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9  Using Arduino / LEDs and Multiplexing / Re: LED coding on: December 26, 2011, 04:47:11 pm
Also noticed, you might want to put

Code:
digitalWrite(13, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(13, LOW);    // set the LED off
  delay(1000);              // wait for a second

  pinMode(12, OUTPUT);

 
  digitalWrite(12, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(12, LOW);    // set the LED off
  delay(1000);  // wait for a second
 
  pinMode(11, OUTPUT);

 
  digitalWrite(11, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(11, LOW);    // set the LED off
  delay(1000);
 
  pinMode(10, OUTPUT);

 
  digitalWrite(10, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(10, LOW);    // set the LED off
  delay(1000);

const int RED_LED_PIN = 9;
const int GREEN_LED_PIN = 8;
const int BLUE_LED_PIN = 7;

// Used to store the current intensity level of the individual LEDs
int redIntensity = 0;
int greenIntensity = 0;
int blueIntensity = 0;

// Length of time we spend showing each color
const int DISPLAY_TIME = 100; // In milliseconds

from loop into setup. If you want to flash each LED colour on before you start mixing colours, I'd put this into setup:
Code:

  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);

const int RED_LED_PIN = 9;
const int GREEN_LED_PIN = 8;
const int BLUE_LED_PIN = 7;

// Used to store the current intensity level of the individual LEDs
int redIntensity = 0;
int greenIntensity = 0;
int blueIntensity = 0;

// Length of time we spend showing each color
const int DISPLAY_TIME = 100; // In milliseconds

and this into the start of loop:

Code:

  digitalWrite(12, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(12, LOW);    // set the LED off
  delay(1000);  // wait for a second

  digitalWrite(11, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(11, LOW);    // set the LED off
  delay(1000);
 
  digitalWrite(10, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(10, LOW);    // set the LED off
  delay(1000);


Or you could turn it into a flash function:
Code:
void flash(int pin){
  digitalWrite(pin, HIGH);
  delay(1000);
  digitalWrite(pin, LOW);
  delay(1000);
}
Then call the function at the start of loop
Code:
flash(12);
flash(11);
flash(10);
Just some ideas.

Onions.
10  Using Arduino / LEDs and Multiplexing / Re: LED coding on: December 26, 2011, 04:37:15 pm
The line
Code:
;for blueIntensity = 0; blueIntensity <= 255; blueIntensity+=5)
should be
Code:
for (blueIntensity = 0; blueIntensity <= 255; blueIntensity +=5){

You added number 5s after some semi-colons for some reason, which will stop it working. Deleting the 5s and sorting out the for loop, we have:

Code:
void setup() {               
  // initialize the digital pin as an output.
  // Pin 13 has an LED connected on most Arduino boards:
  pinMode(13, OUTPUT);     
}

void loop() {
  digitalWrite(13, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(13, LOW);    // set the LED off
  delay(1000);              // wait for a second

               
  // initialize the digital pin as an output.
  // Pin 13 has an LED connected on most Arduino boards:
  pinMode(12, OUTPUT);

 
  digitalWrite(12, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(12, LOW);    // set the LED off
  delay(1000);  // wait for a second
 
 
 // initialize the digital pin as an output.
  // Pin 13 has an LED connected on most Arduino boards:
  pinMode(11, OUTPUT);

 
  digitalWrite(11, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(11, LOW);    // set the LED off
  delay(1000);
 
 
 // initialize the digital pin as an output.
  // Pin 13 has an LED connected on most Arduino boards:
  pinMode(10, OUTPUT);

 
  digitalWrite(10, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(10, LOW);    // set the LED off
  delay(1000);




// LED leads connected to PWM pins
const int RED_LED_PIN = 9;
const int GREEN_LED_PIN = 8;
const int BLUE_LED_PIN = 7;

// Used to store the current intensity level of the individual LEDs
int redIntensity = 0;
int greenIntensity = 0;
int blueIntensity = 0;

// Length of time we spend showing each color
const int DISPLAY_TIME = 100; // In milliseconds





  // Cycle color from red through to green
  // (In this loop we move from 100% red, 0% green to 0% red, 100% green)
  for (greenIntensity = 0; greenIntensity <= 255; greenIntensity+=5) {
        redIntensity = 255-greenIntensity;
        analogWrite(GREEN_LED_PIN, greenIntensity);
        analogWrite(RED_LED_PIN, redIntensity);
        delay(DISPLAY_TIME);
 

  // Cycle color from green through to blue
  // (In this loop we move from 100% green, 0% blue to 0% green, 100% blue)
 for (blueIntensity = 0; blueIntensity <= 255; blueIntensity +=5){
        greenIntensity = 255-blueIntensity;
        analogWrite(BLUE_LED_PIN, blueIntensity);
        analogWrite(GREEN_LED_PIN, greenIntensity);
        delay(DISPLAY_TIME);
 

  // Cycle cycle from blue through to red
  // (In this loop we move from 100% blue, 0% red to 0% blue, 100% red)   
  for (redIntensity = 0; redIntensity <= 255; redIntensity+=5)
        blueIntensity = 255-redIntensity;
        analogWrite(RED_LED_PIN, redIntensity);
        analogWrite(BLUE_LED_PIN, blueIntensity);
        delay(DISPLAY_TIME);
       
  }
  }
}

Which compiles fine.

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11  Using Arduino / Networking, Protocols, and Devices / Re: Shorting two wires via wifi on: December 25, 2011, 11:46:31 am
It looks like the 'Ethernet' board would be perfect, although you'll need a connector to upload your program.

For the hardware, I'd use a relay. Wire it up as shown here: http://arduino.cc/playground/uploads/Learning/solenoid_driver.pdf, only with a relay in place of the solenoid. Connect the relay contacts up to the wires for the gate, then when the arduino receives something from a web client saying to turn it on, the gate will (should) open.

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12  Using Arduino / Project Guidance / Re: Using GSM shield to send text messages from a alarm system on: December 21, 2011, 02:59:13 pm
page 120 of http://www.yourportablelab.com/downloads/schematics/AT_Command_Reference.pdf covers the details that should allow you to send text messages with the ebay shield, although it seems much more complex than the sparkfun shield.
Out of the two, I'd pay the extra for the sparkfun shield, then you would know it will work, although it does cost more. Another option to consider would be to buy an ethernet shield. With the right code, you can make it send emails. I read somewhere about services that take an email you send them then send that as a text to a phone. If you can find such a service, that would provide another option.

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13  Using Arduino / Networking, Protocols, and Devices / Re: Shorting two wires via wifi on: December 21, 2011, 12:09:04 pm
Yes, the arduino would have the shield, then when a client connects (or connects and enters a password) the gate can be made to open. A relay would be a better idea than the transistor, as long as you wire it up correctly.

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14  Using Arduino / Project Guidance / Re: Using GSM shield to send text messages on: December 21, 2011, 11:19:56 am
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Where can I get a good GSM shield (I'm in the UK)?
Ebay!

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I have not long moved into a new house and I'm starting to fit an alarm system.
I have noticed the main panel has got a few relay outputs, including one for the alarm condition.
I was hoping to be able to use an arduino with a GSM shield to send me and my girlfriend a text message if the alarm condition has activated.
This doesn't sound too hard... Wire up the relay contacts in the same way you would wire up a normal switch (only the relay does the equivalent of pressing the button), read the state of the input it's connected to, then send a text if it is high.
Personally, I'd be very careful when playing with a securiy system. Unless you're absolutely sure about what you're doing, the results could be very dodgy. On the other hand, if you are sure, you could end up with a very useful system indeed!

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15  Using Arduino / Networking, Protocols, and Devices / Re: Interfacing Bluetooth Dongle with Arduino on: December 21, 2011, 11:11:45 am
There is now a USB host shield available (http://www.skpang.co.uk/catalog/usb-host-shield-p-710.html) that would make connecting the dongle easier.

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The USB Host Shield contains all of the digital logic and analog circuitry necessary to implement a full-speed USB peripheral/host controller with your Arduino. This means you could use your Arduino to interface with and control any USB slave device - thumbdrives, digital cameras, bluetooth dongles, and much more!

In order to use it though, you would need to wirte out the drivers needed for it to work, unless someone else has. Connecting it will be easy, actually doing something with it will not. You might be lucky and find some details on the playground about the idea...

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