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901  Using Arduino / Programming Questions / Re: Saving sensor readings on arduino on: July 11, 2013, 11:21:42 am
Get an SD card and shield; plenty of examples out there for this.

Alternatively, you could save it to be EEPROM, but this would be very limited in the amount you can save.
902  Using Arduino / Programming Questions / Re: Binary Communication - Command Request Question on: July 11, 2013, 11:01:59 am
Code? Example Response?
903  Using Arduino / Project Guidance / Re: Stoplights Project help requested~ on: July 10, 2013, 06:53:40 pm
If I do that wouldn't there be a constant 5V going into the input, negating the use of the switch? or am I misunderstanding that?

It would be "pulled" to 5V via the internal resistance. Once the switch is pressed, the input pin is shorted to GND.
904  Using Arduino / Programming Questions / Re: Programming a clock on: July 10, 2013, 06:49:53 pm
I bet that the code you have doesn't do what you're intending it to do, but to display those ints on the LCD, simply use lcd.print(). If you want it formatted a specific way, such as HH:MM:SS you can use sprintf().
905  Using Arduino / Programming Questions / Re: Just plain don't undrestand on: July 10, 2013, 05:55:02 pm
All code, aside from global variable declaration/initialization, needs to be inside a function. This is your loop function:

Code:
void loop() {
  int relayState = digitalRead(relay);
 }

None of this code is inside a function:

Code:
  if (relayState) == LOW)
  }
   digitalWrite(led, LOW);
{
  if (digitalRead(relay) == HIGH);
}
digitalWrite(led, HIGH);

 }

And next time, post error messages when you get them, don't expect us to guess.
906  Using Arduino / Programming Questions / Re: Programming a clock on: July 10, 2013, 05:53:34 pm
Display where?

That code looks suspiciously like the same code you started with in your other 5 page thread, despite the numerous suggestions.
907  Using Arduino / Project Guidance / Re: Stoplights Project help requested~ on: July 10, 2013, 05:39:29 pm
Could you explain why it isn't needed

Because there are internal resistors that perform the same function and simplify the wiring.

why it was included in the first place

I didn't write the starter set, so I have no idea.
908  Using Arduino / Programming Questions / Re: Serial output all ÿ, but code was working before on: July 10, 2013, 04:17:22 pm
Device 1 is sending either 3.3V or 0V relative to its GND to Device 2. What happens when Device 1's GND is 5V higher than Device 2's GND? Device 2 will read 8.3V and 5V which would both be interpreted as HIGH. That is why the grounds need to be connected.
909  Using Arduino / Project Guidance / Re: Stoplights Project help requested~ on: July 10, 2013, 03:50:52 pm
Get rid of the resistor all together on your switch and enable the internal pullup. Coding wise you'll want to setup a finite state machine.
910  Using Arduino / Programming Questions / Re: Serial output all ÿ, but code was working before on: July 10, 2013, 03:38:35 pm
Forgive my ignorance, but SHOULD the grounds be connected?

3.3V isn't an absolute value, it's 3.3V from some reference point, usually ground. If the two grounds are different, then 3.3V may be an entirely different energy level amongst the devices. Without the grounds connected it would be like trying to determine if somebody is taller than you while they are standing on a stool. If two devices are trying to communicate and are have separate power supplies, their grounds need to be connected.

Quote
The basic problem I'm having is that I need to power 2 devices with 3.3V. When I tried to connect both to the same 3.3V pin on one board, it didn't seem to work. Not sure why, but my guess is that the voltage was right but the amperage (guessing here) was wrong/insufficient. Thus the attempt with 2 boards.

You need to look up, or measure the current draw of the two devices that you are powering. You then need to make sure it's under the rated maximum of the 3.3V regulator.
911  Using Arduino / Programming Questions / Re: Serial output all ÿ, but code was working before on: July 10, 2013, 03:10:55 pm
So you were getting VCC from a board that was powered by a wallwart, but were trying to connect it to a different board that was getting USB power? I'm guessing the grounds of these two boards weren't connected?
912  Using Arduino / Programming Questions / Re: Using java and lcd library on: July 10, 2013, 10:43:32 am
You don't have a choice on what language to use.

You can choose whether to use pure C++ or Arduino-mucked-about-almost-C++, by putting your code in a .ino file or a .cpp file.

In other words, you can choose the dialect, but not the language.
913  Using Arduino / Programming Questions / Re: multiple interrupts for 3 button LCD screen on: July 10, 2013, 12:49:16 am
Why do you want to use an interrupt?
914  Using Arduino / Programming Questions / Re: 'byte' does not name a type on: July 09, 2013, 11:58:48 pm
Looks like you are trying to use a library that is intended for a newer version of the IDE (>=1.0) with an older version of the IDE (< 1.0)
915  Using Arduino / Programming Questions / Re: Using java and lcd library on: July 09, 2013, 10:35:37 pm
Would you recomend c++ over using arduino language?

You don't have a choice on what language to use.
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