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1  Using Arduino / Project Guidance / 2x ID12s on: April 03, 2012, 04:26:28 am
I'm having a bit of an issue running two ID12s.

They don't work if both are connected and enabled. They are around 10cm from each other, and if I pull the Reset connection (normally to +5v) on one, then the other works ok.

Is there a way around this? I have no means to try them further away at the moment, as I don't have another breadboard to hand.
2  Using Arduino / Sensors / "Long" range RFID on: March 29, 2012, 03:35:16 am
I have a project where I'd like to detect presence based on RFID. Kind of like the keyless start/entry systems you find on cars.

I essentially need to be able to detect whether someone with an RFID card in their pocket is inside the car or just outside.

I'm guessing the solution is a few ID2s and some decent sized antennas, but what are other people's thoughts on this, and where can I source the antennas from?
3  Using Arduino / Displays / Re: HD44780/KS0066U upside down? on: March 21, 2012, 04:50:21 pm
Not necessarily both sides.

Flush with the top whilst having the pins on the bottom would be fine.

Looking at the one I have, it could easily be cut flush with the metal cover on the bottom, you'd just need to replace the ground for the backlight.

That gives me space in the wrong place, though - hence asking about the upside down thing :p
4  Using Arduino / Displays / HD44780/KS0066U upside down? on: March 19, 2012, 05:19:57 pm
Is it possible to flip what is displayed on the screen, so it is "upside down"?

The screen I want to use has the header pins along the top - due to space constraints, I need them along the bottom. Can it be done?

Failing that, does anyone know of a 20x4 screen with a negative red backlight that doesn't have loads of PCB sticking out top and bottom?
5  Using Arduino / LEDs and Multiplexing / Re: Driving 7 "point" LCDs on: March 16, 2012, 11:10:25 am
Pretty sure it's LCD, but characters are in 7 segments.
6  Using Arduino / LEDs and Multiplexing / Re: Driving 7 "point" LCDs on: March 16, 2012, 10:02:28 am
Oops, this should have been in the Displays forum.
7  Using Arduino / LEDs and Multiplexing / Driving 7 "point" LCDs on: March 16, 2012, 08:34:08 am
How are these normally operated? I'm talking about the displays that make up characters like this:

Is it just a multiplexer, some kind of proper controller or is it completely random?

I'm planning on interfacing with a display on my car (which isn't on the CAN unfortunately), and I'm just curious before actually taking it out and having a look (bit of a pain, as the whole dash top has to come out). [/code]
8  Using Arduino / Networking, Protocols, and Devices / Re: VLAN tagging on: March 15, 2012, 12:33:48 pm
I'm trying to implement vlan tagging?
9  Using Arduino / Programming Questions / Re: Random Lockups on: March 15, 2012, 07:21:24 am
As I said, because I'm clearing the line first, it's fine.

Because I have future scenarios where I will want to center it inside a smaller space (because the right portion of the line is displaying something else - hence why width is configurable), it's more practical to do it this way.

I could clear the width that is set, but quite often I'm clearing multiple lines, so clearing is handled with a different function.
10  Using Arduino / Displays / Re: HD44780 compatible display only showing small section on: March 15, 2012, 04:23:01 am
Ordered a new one, unplugged old one, plugged in new one and the same code works perfectly.

The display was indeed faulty.
11  Using Arduino / Programming Questions / Re: Random Lockups on: March 15, 2012, 03:20:59 am
Well, this was my solution in the end - as I'm selectively clearing the lines I need to before calling centerText(), there's no point printing a load more wasted spaces to the LCD

void centerText( String text, int row, int width=LCDWIDTH )
   int strlen = text.length();
   if( strlen < width && width-strlen > 2 )
     int padding = (width-strlen) /2;
     lcd.setCursor(padding, row);
     lcd.setCursor(0, row);
12  Using Arduino / Programming Questions / Re: Random Lockups on: March 14, 2012, 04:55:51 pm
Thanks for the tips guys, that makes a lot of sense.

As for why I need space after the name, whilst in normal circumstances the line would be cleared before anything would be written to it again, in the case that it isn't, those extra spaces ensure that there are no leftover characters from the previous text.

This function was born purely out of laziness if I'm honest, I think what I'm going to do is just clear the line and then work out the padding from the left as an int to determine where the cursor should be placed rather than butchering the original string.
13  Using Arduino / Programming Questions / Re: Random Lockups on: March 14, 2012, 12:06:33 pm
I've finally traced it down to the centerText() function, however I'm failing to see what the issue is

String centerText( String text, int width=LCDWIDTH )
   int strlen = text.length();
   if( strlen < width )
     int padding = (width-strlen) /2;
     String space = String(" ");
     for(int i=1;i<=padding;i++)
       text = String(space + text + space);
     if( text.length() < width )
       text = String( text + space );
   return text;
14  Using Arduino / Programming Questions / Re: Random Lockups on: March 14, 2012, 11:53:50 am
Ok, after some playing, it seems to be something to do with this code, as removing it removes the issue:

char nameLen[4];
        nameLen[3] = '\0';
        client.find("NameLen: ");
        client.readBytes(nameLen, 3);
        int iNameLen;
        iNameLen = atoi(nameLen);
        char name[iNameLen+1];
        name[iNameLen] = '\0';
        client.find("Name: ");
        client.readBytes(name, iNameLen);             
        lastNamePrint = millis();
        lcd.setCursor(0, 2);
15  Using Arduino / Programming Questions / Random Lockups on: March 14, 2012, 11:37:34 am

I'm having issues where by if I continually swipe a card over the RFID reader in reasonably quick succession, the unit locks up.

I have a feeling it is an issue with the rfidRead() function, however this is nothing more than a gut feel.

Can anyone see anything obviously wrong with my code?

Code is too long to paste here, so I've put it on pastebin:
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