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4261  Using Arduino / Project Guidance / Re: Recursive video on: November 28, 2011, 11:54:00 pm
I'm unsure how this relates to Arduino.
4262  Using Arduino / General Electronics / Re: Soldering for the beginner. on: November 28, 2011, 11:43:37 pm
Also, caffeine doesn't help. smiley
I find that beer works though.  Although, a calibrated amount is required.  It doesn't take too many to get to the point of diminishing returns.
4263  Using Arduino / Programming Questions / Re: sleep mode on: November 28, 2011, 08:47:47 pm
Keep in mind that sleep mode only puts the ATmega328 to sleep, not the Arduino.  The Waveshield, Power LED, 8U2 (or FT232 on older boards), 5V reg, and 3V3 reg are all going to still be running.  You might be saving a few millliamps while the rest of the circuit is still drawing 10s of milliamps.
4264  Using Arduino / General Electronics / Re: Controlling a 4.5v 500 mA Santa Claus on: November 28, 2011, 07:32:45 pm
Why would you break the negative connection?  Conventions say break positive to keep anything from floating.

The optocoupler is only rated for 100mA.  The Relay you are using has a coil rating of 12V.  Neither is going to work for you.  Unless you use a transistor with a 12V supply to activate the relay.
4265  Using Arduino / Programming Questions / Re: When arduino board is reset DS1307 resets too! on: November 28, 2011, 07:05:35 pm
The problem is... when you reset the arduino, how do you know not to write to the RTC??

A separate sketch should be used to program the RTC.  Or there should be hooks to only program the RTC in certain conditions.  For example, on my binary clock I send a 'T' followed by the seconds since epoch over serial.  In that situation, the RTC is set.
4266  Using Arduino / Programming Questions / Re: When arduino board is reset DS1307 resets too! on: November 28, 2011, 05:12:18 pm
The Time Library keeps track of time.  The time is set from a variety of sources, such as the RTC.  The confusing step is that you can then set the time used by the Time library independent of the RTC.  You are only setting the time inside your sketch and not actually writing it to the RTC.

For example:
if(timeStatus()!= timeSet)  //Doesn't check the RTC.

long pctime = 1322518310;  // number of seconds since epoch

setTime(pctime);  // This sets the time in the library
RTC.set(pctime);  // This sets the time into the RTC.

Until you call RTC.set() the RTC isn't actually being used for anything.
4267  Using Arduino / Programming Questions / Re: DS1307 RTC library on: November 28, 2011, 10:51:03 am
" int minval = (now.minute(), DEC);"

This doesn't make sense.  The argument ", DEC" tells Serial.println what format to print the number as (DECimal, HEXadecimal, OCTal, etc).

Should be:
int minval = now.minute();
4268  Using Arduino / Programming Questions / Re: DS1307 RTC library on: November 28, 2011, 10:09:04 am
i looked at the library from here, but i can't find much documentation about it
You really shouldn't need much in the way of documentation.  The examples provided with the library and on Ada's tutorial page tell you how to set the time and read the time.  That's all you need to do.

Don't overcomplicate your design by trying to set alarms or anything.  Just write your code to check what time it is and if you should be turning lights on or off. 
4269  Using Arduino / Programming Questions / Re: Limits on size of String and using indexOf() ? on: November 27, 2011, 02:27:22 pm
Which Arduino board / ATmel processor are you using?

where data is the incoming character.  This creates a String of typically about 200 characters.
Keep in mind that when a String object is concatenated, a new buffer the size of the original string plus 1 is created.  Then the new result is copied into the original buffer.  This means you are using 2x the storage required during the operation.  So if you have 200 characters and add one, you at that moment, using 400 bytes.

I did some tests and found that using indexOf() on Strings of more than about 160 characters, will fail, returning -1.
How did you generate these 160 characters?  Was this by concatenating strings until you got 160 characters to search?  If so, you might be running out of RAM which means the String isn't actually storing what you expected which is why indexOf is failing. 

Also can anyone suggest perhaps a better approach to the problem?  Thanks!
If you know the maximum number of characters you are going to deal with, then just use a character array.
4270  Using Arduino / Programming Questions / Re: Simple Scheduler on: November 27, 2011, 11:11:35 am
You might also want to look at Metro:
4271  Using Arduino / General Electronics / Re: Looking for a Arduino Mega 2560 development shield... on: November 27, 2011, 10:39:21 am
I am looking for a board that will permit a "Arduino Mega 2560" and any standard/mega shield to be plugged into it, with the relevant connections, switch/link selectable.

Does anyone know of such a board?
4272  Using Arduino / General Electronics / Re: Soldering for the beginner. on: November 27, 2011, 10:37:18 am
This has probably been covered a million times, but i'll ask anyways.
Indeed.  Although using your topic title as the search only finds around 400,000 pages on Google.

Hakko FX-888  Good Price... Excellent Tool.
Agreed.  I moved to the FX-888 recently.  The color scheme is silly but the iron works very well for the price.
4273  Using Arduino / General Electronics / Re: used digital multimeter on: November 27, 2011, 12:26:30 am
My old analog multimeter broke this morning so does anyone know of a website that sells used digital multimeters.
4274  Using Arduino / Project Guidance / Re: Detect VGA signal on: November 26, 2011, 05:51:00 pm
I have no idea how to implement ic2. do you have a quick down and dirty schematic / code example? also this wouldn't interfere with the signal transmission?

I'd worry more about interfering with the controlled impedance of the VGA's signal lines than the relatively slow I2C bus. You don't have to actively participate, just watch for the data or clock signal to toggle.  That will tell you the monitor is trying to talk to the projector.
4275  Using Arduino / Project Guidance / Re: Streaming video with my project on: November 25, 2011, 11:06:20 pm
Use Ustream?
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