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Member Since: December 18, 2009

Country: United States

  • If it is similar to the DS1052E/DS1102E, it supports the USB TMC protocol - it's standardized!
    However USB TMC protocol support in the Linux kernel isn't well maintained - last time I tried to use it, the mainline modules failed. However there was source code from Agilent worked. It's poorly documented so it took a while to find a good example program for interfacing with TMC equipment.
    I'll try to dig up my old code and put it up on github or something as a starting point for someone...

  • As a tradeoff - the NXP PCA9635 has higher port density and lower cost. Main disadvantages:
    1) Needs current limiting resistors (but so does the 595)
    2) It's surface-mount only (but compatible with Sparkfun's SSOP breakouts)
    Major advantage: High-rate PWM done by the hardware, which offloads the software in the controlling AVR.
    Basic example code for driving it using an AVR is at https://github.com/Entropy512/DMX_PCA9635
    The above will work with Arduino-compatible hardware, however, I use straight avr-gcc and not the Arduino IDE. Obviously in this case the DMX reception code can be torn out.
    Another option you could investigate are prebuilt WS2801 nodes controlled by an AVR.

  • Which board? The Arduino?
    I'm fairly certain that the ATMegaXX8s used in most Arduinos (not Arduino Megas) do not support XRAM.
    Not sure if the Arduino Megas wire out the required pins of the Mega2560 for XRAM support.

  • The reason for this is that if you didn't do periodic power injection, you'd need MASSIVE power/ground wires to avoid problems with the voltage dropping by the end of the string.

  • Philips has a number of patents on I2C control of RGB LEDs, and I think may also have some patents on general RGB control via serial busses (that applies more broadly than just I2C)
    In addition, Color Kinetics has a ton of patents on RGB control - it is basically impossible to do RGB work with LEDs in the United States without infringing on either a CK or Philips patent.
    Hopefully in Sparkfun's case, their importer has paid the appropriate licensing fees. (Most likely they have, which is why the strips are MUCH more expensive per node than direct imports from Asia, which have a risk of getting seized by customs.)

  • I think that's the whole point of the contest, and one of the main reasons for its name.

  • Light on specs - does it have independent charging channels for each cell?
    Independent channels per cell is a very important feature to keep sets of cells balanced, and is available in chargers that cost only $25-30.

  • Still, $13 for only $2-3 in components?
    Although you are paying royalties on at least two patents.
    For those that want to DIY it - http://github.com/Entropy512/I2C_RGB - about the only remaining thing needed for that project is some work on making the USI TWI implementation more reliable. (I haven't had time for that in the past few months as I have been focusing more on working with the PCA9635.)

  • I see the product pages for the Rebel heatsink and the Rebel optics holder, but I don't see a product page anywhere for the Tyco solderless LED holder, only links to the datasheet.
    Most people would likely find the LED emitter holder far more useful than the optics holder... Especially since the optics holder isn't too useful unless combined with the emitter holder...

  • 1000 times as bright as a standard LED?
    I'd be curious wheere those LEDs were sourced. The highest power LEDs I have ever seen in the "classic" form factor are 0.5 watt 5-chip LEDs rated at 100 mA forward current, and have the chips in a parallel configuration (i.e. 5 times the maximum forward current, but the same Vf).
    Standard LEDs are typically rated at 20 mA forward current.
    So even if the LEDs used here were 5-10 times more efficient than a standard LED (highly unlikely), they would at best have 25-50 times the luminosity of a standard LED of the same color. Given that their efficiency is probably similar to standard LEDs, they are likely only 5 times as bright.

No public wish lists :(