USB controlled LED on/off and dimmer

[bd13]

for a computer mod project i want to be able to control a tricolor LED (red, green, blue), just think 3 separate LEDs and it will make things easier, from a USB port and have the options of turning the LEDs on/off, and dimming them. this will allow every color to be visible. i found almost exactly what i wanted from this site:
**broken link removed**
only problem is it costs 60$, controls 64 LEDs, and is too big to fit in the spot i need it to fit in. and if your wondering i was going to wire the LEDs to run off the 5v USB power.

Because of these factors i'm considering the posibility of building my own. anyone have any insite on this? anyhelp would be appreciated. thanks

 

[Someone Electro]

well you can run led of the 5V but diming the spretly that is complicated .Interfacing whith USB is wery hard

so use rather an PIC conected to the serial prort or somtin

 

[bd13]

would if i had serial ports. usb is all i have.

 

[bonxer]

I just ordered some tri-colored LEDs from futurlec.com and I must say they're pretty sweet, so if you'd rather use them as opposed to invidual R, G, and B's, there's a supplier. If your requirement is that it has to be connected to a computer by USB so you can write software to control it, that sounds like more of a software project than a hardware project, and I have no idea where to begin when it comes to USB stuff. If you're just wanting the PC connection to be able to send data patterns to it, simply using the serial or parallel port would be easier. I typed half this reply before noticing your "no serial available" post.

As for making a device to control voltage/current levels to the LEDs, you could do that with a digital to analog converter. Or you could make your own D2A with an op-amp, like in this writeup: **broken link removed**

This would be very bulky to make your own that's scalable to 64 leds. But your first sentence had "a tricolor LED" which I interpret to mean singular, so you only want to adjust the color of one tri-color LED. You would only need to build three A2D's, or perhaps get a pre-made A2D chip, so the hardware side of the single tri-color LED adjuster is simple. Good luck with a USB connection software side.

 

[Optikon]

for a computer mod project i want to be able to control a tricolor LED (red, green, blue), just think 3 separate LEDs and it will make things easier, from a USB port and have the options of turning the LEDs on/off, and dimming them. this will allow every color to be visible. i found almost exactly what i wanted from this site:
**broken link removed**
only problem is it costs 60$, controls 64 LEDs, and is too big to fit in the spot i need it to fit in. and if your wondering i was going to wire the LEDs to run off the 5v USB power.

Because of these factors i'm considering the posibility of building my own. anyone have any insite on this? anyhelp would be appreciated. thanks

For USB interface, get a device controller (check cypress) - $8USD
For dimming, control digital pots. Check Xicor.

 

[checkmate]

USB is always a host-client connection, unlike serial or parallel, you need to have a smart client. So the minimum prerequisite is to have a microcontroller/fpga/asic, and a usb device controller. For your setup, a microcontroller and a usb-to-serial convertor chip like the ftdi chips should be the simplest method, no need to fiddle with the usb protocol.

If you have no background in microcontroller programming, now may be a nice time to start. The ftdi chip builds a serial interface to mask the usb complexities. Therefore, for the PC side, all you have to di is to interface the virtual COM port provided by ftdi drivers.

For the dimming part, just drive the leds with a pwm signal from the microcontroller.