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1  Using Arduino / Displays / Re: LCD shield - understand the mapping between Arduino and shield pins on: November 23, 2012, 05:57:34 pm
Thanks liudr for your help.

I bought it on eBay from a supplier based in Hong Kong.

Yes, I found the schematics - I have attached it.

But I can't find it in there how I could find out about the issue I am talking about - don't you need the PCB layout to see that? - sorry I am a newbie.
2  Using Arduino / Displays / LCD shield - understand the mapping between Arduino and shield pins on: November 23, 2012, 04:27:06 pm
Hi.

I hope you can see the image I have attached.

I bought a LCD shield, compatible with the DFRobot LCD Keypad Shield. Then I attached this shield to my Arduino Uno board.

I was trying to figure out how to access the Arduino pins through the shield, therefore I make a sketch that makes a led on digital pin 3 blink.

The system works if I connect the jumper wire to the spot marked with A in the picture, as expected, as that is the pin directly inserted into the Arduino header.

Then, I tried to attach the wire to the hole marked with B, as that is next to A, but the system didn't work. I had to insert the jumper wire as shown in the picture.

To me, that is totally counterintuitive as the hole I am using is next to pin 4 of Arduino, not pin 3.

Am I missing something? How could I have anticipated that? Is there a standard for how shields map Arduino pins?

Thanks a lot for your help!
Dan
3  Using Arduino / General Electronics / Re: What can't you do with PWM compared to DAC on: November 16, 2012, 11:17:44 am
Very interesting, CrossRoads - thanks a lot.

Is the "low pass filter" you were talking about integrated into the microcontroller or is it something I should take care of?

Dan
4  Using Arduino / General Electronics / What can't you do with PWM compared to DAC on: November 16, 2012, 10:49:14 am
Hi.

I am learning Arduino. I have read the analogWrite actually uses a digital signal, via the PWM technique.

I also read that is good enough for dimming LED's, controlling motors, generating audio...a lot of things, after all.

My question is, what are the main things you can't achieve with PWM, but you definitely need DAC instead? I am asking in general, but also particularly in the Arduino/microcontrollers arena.

Thanks,
Dan
5  Using Arduino / Programming Questions / Re: Problems using System.println with a floar variable on: November 14, 2012, 11:33:46 am
I can't see it - probably I am too new to the forum for being able to vote :-(
6  Using Arduino / Programming Questions / Re: Problems using System.println with a floar variable on: November 14, 2012, 11:31:36 am
Thanks a lot, that worked!

How can I vote for your answer so to increase your karma?
7  Using Arduino / Programming Questions / Problems using System.println with a floar variable on: November 14, 2012, 10:48:02 am
Hi.

This is my test sketch:

Code:
void setup()
{
  Serial.begin(9600);
 
  float a = 1.23;
  Serial.println(a); 
 
  float b = 5/255;
  Serial.println(b);
}

void loop()
{
}

This is its output:
Code:
1.23
0.00

Can you please help me understand why it is printing 0.00 ?  How can I print my float variable?

Thanks,
Dan
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