Show Posts
Pages: 1 ... 62 63 [64] 65 66 ... 115
946  Using Arduino / LEDs and Multiplexing / Re: RGB SMT LED Cube, resistors, drivers, and shift registers. on: October 30, 2012, 06:20:05 pm
The way I have made mine structurally sound is to use a plastic frame, but I have access to a laser cutter at the University where I study so that may not be an option. The other thing I considered doing was to use plastic rod which can be gotten from hobby shops, and then either glue or melt the layer wires into it to give it rigidity.

What values of resistor do you have available? If you have enough 3.3k resistors, you can put two in parallel to get 1.65k which would give you exactly 3.3V. Alternatively any three resistors of the same value with the top of the potential divider being two in parallel will result in 3.3V

Code:
o-----+--+
      |  |
    R [] [] R
      |  |
      +--+-----o
      |
    R []    Where R = any value - preferably between 1k and 10k
      |
o-----+--------o
947  Using Arduino / LEDs and Multiplexing / Re: RGB SMT LED Cube, resistors, drivers, and shift registers. on: October 30, 2012, 01:30:52 pm
1.8k and 3.3k tend to work well. 
948  Using Arduino / LEDs and Multiplexing / Re: RGB SMT LED Cube, resistors, drivers, and shift registers. on: October 30, 2012, 11:50:26 am
What I am saying is that when you disconnected the 5V line, it stayed working because there are diodes built into the chip. This is a very bad way of operating the chip.


When you connected 3.3v, you need to level shift signals from 5v down to 3.3V otherwise there will be excessive currents flowing through the same built protection diodes which will damage the chip.

Level shifters can range from dedicated IC's to Transistors, to basic resistor potential dividers.
949  Using Arduino / LEDs and Multiplexing / Re: RGB SMT LED Cube, resistors, drivers, and shift registers. on: October 30, 2012, 04:43:40 am
Clamping diodes on the inputs of the shift register IC. Basically if you remove Vcc, power can flow from an input which is set at logic 1 to Vcc via the protection circuits. This is not good for the IC as the protection circuits aren't designed to power the thing.
If theArduino is running at 5V still you also have a problem as you are running the shift register at 3.3v meanung that the inputs will be far above the absolute maximum allowed voltage of Vcc+0.5V
950  Products / Arduino Due / Re: pgmspace.h is not supported? on: October 30, 2012, 04:09:06 am
If you put it in the folder I suggested, you can just use:

#include <avr/pgmspace.h>
 
to include it in your library, meaning you can use the same stement for both due and avr.
951  Products / Arduino Due / Re: pgmspace.h is not supported? on: October 29, 2012, 07:59:34 pm
That works well if you put it in the folder:
Code:
<Arduino Dir>\hardware\arduino\sam\libraries\avr\avr\

One query though, aren't you missing the const keyword? In which case surely everything gets stuck in the RAM, or have I missed something.

In which case should you define 'PROGMEM' as 'const'
#define PROGMEM const
I suppose the problem with that is if people put the PROGMEM term after the variable name in which case it wont work.
952  Using Arduino / Programming Questions / Re: Can not get a scketch to upload using xbees. on: October 28, 2012, 02:02:20 pm
I don't think they can, i think they have to be read locally.
953  Using Arduino / Programming Questions / Re: Can not get a scketch to upload using xbees. on: October 28, 2012, 12:42:16 pm
I thought the auto reset would work as the newer boards have this built in.
again thanks for your input.

They do, but it is part of the USB-Serial converter built in. If you are using xBees, then I presume you are bypassing this?

Maybe you could do a quick sketch of how you have wired the xBee to your board.


Also, you said you tried changing the Baud rate? This is programmed into the xBees as well as the bootloader, so if one of the xBees is 30feet in the air, how did you set it to the faster 57600 baud rate required?
954  Using Arduino / LEDs and Multiplexing / Re: RGB SMT LED Cube, resistors, drivers, and shift registers. on: October 28, 2012, 10:27:39 am
I have been working on something similar, only mine is 12x12x12. It really is an awful nightmare wiring up all the LEDs. The worst part is I finished doing it using magnet wire, only to have insulation in the wire break down and short everything out, so I need to rewire all the common wires.

For mine I am using TLC5951's for the cathodes (though TLC5947s were my first choice but they are too slow for a cube the size of mine), and 4-16 line decoders wired up to create a 7 to 72 line decoder driving P-ch MOSFETs for all the anode common lines.
By using these IC's mine is capable of 36bit colour (though I have limited it down to 24bit).
955  Using Arduino / Programming Questions / Re: Can not get a scketch to upload using xbees. on: October 28, 2012, 10:23:19 am
I was meaning that if you are trying to use an xbee to program the board, you have to reset the board just before uploading as the autoreset feature wont happen.

You can try connecting the RTS pin of the xbee on the arduino end via a 100nF capacitor to the arduino's reset pin. Or you just have to press reset manually - whether that is with a button, or by momentarily shorting the reset pin to ground with a wire is up to you.
956  Using Arduino / Programming Questions / Re: Can not get a scketch to upload using xbees. on: October 28, 2012, 09:19:18 am
You couldn't just change the boards.txt file as that is hardcoded into the bootloader (you would have to recompile and reflash the bootloader to change it).

Does it work if you disconnect the RTS line, and instead press the reset switch on the arduino just before uploading begins?
957  Products / Arduino Due / Re: pgmspace.h is not supported? on: October 27, 2012, 07:15:18 pm
Yeah, you don't need pgmspace any more. The Due and other arduinos are of different architecture, and with the due simply declaring const will put it in the program space.

This is what I have put at the top of one of my library files to make the two compatible:

Code:
#ifndef __arm__
#include <avr/pgmspace.h>
#else
#define PROGMEM const
#define F(x) x
#endif

And then for example you can use it like:

Code:
PROGMEM byte myArray[500] = {1,2,3,4,5,6, ...};


The advantage of doing it this way is that when you are using an avr, the #include statement will be valid.
958  Products / Arduino Due / Re: Missing RAM Pins on: October 27, 2012, 07:09:26 pm
With the Due you can put them at the USB connector end now that they have switched to uUSB  smiley-razz
959  Using Arduino / Programming Questions / Re: Can not get a scketch to upload using xbees. on: October 27, 2012, 03:40:54 pm
The arduino bootloader doesn't run at 9600 Baud.

The value depends on which bootloader you have, and you can find this out by looking in the boards.txt file.
960  Products / Arduino Due / Re: Missing RAM Pins on: October 27, 2012, 12:09:22 pm
Unfortunately they are connected in the eagle file.

It would be possible to disconnect them as the trace joining the two is accessible on the bottom of the board, however you would still be left having to run a wire to bring the NRD pin out.

So really, unless you can set the A5 pin to be an input, and then use the external memory with structs which contain a maximum of 32bytes, and store those structs in the memory aligned at 128byte boundaries, then sadly the external memory capability is not possible.
That right there severely cripples the Due's capability and the number of possible uses for it.
Pages: 1 ... 62 63 [64] 65 66 ... 115