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Re: Questions on Single Board Computers

Mark Allyn ha scritto lo scorso 11/06/2006 23:01:
> Hello:
> I need some help trying to select a single board computer
> for a project that I am engaged in.
> The single board computer will be driving an array of approximatley
> 400 to 500 tri-color LED's that will be sewn into a piece of clothing.
> Each tri color LED has emitters for red, blue, and green. These three
> colors are combined to form any other color.
> This means that I will have about 1200 to  1500 individual light
> levels to control in real time.
> Further, as this is a piece of clothing, it needs to run on a 12
> volt battery. I will not have access to the mains.
> I plan to use a serial packet transmission to get the brightness
> information to each LED. I am currently designing the receive (using
> verilog and most likely a Xilinx CPLD for the packet receive and
> pulse width modulation to perform the dimming (LED brightness control
> is said to be the best then done by pulse width modulation). That
> part of the project I see no problem. There is already a lighting
> control protocol, called DMX, for which I have already created
> verilog HDL for implementation.

In addition to all hints you have collected, I would like to suggest
also another solution: an array of Philips PCA9635. They show following
pros and cons:

+ pros
  + you can put together up to 126 of such devices on a single I2C bus,
    allowing you to control up to 2016 LEDs
  + they feature integrated PWM control and LED driver
  + TSSOP28 (SOT361-1) package is very compact (9.7 x 4.4 mm) and even a
    high number of them will waste not so much room
  + I2C bus is very simple to control and every SoC/SoM have a master
    device on board
  + PCA9635 features standard (100 kHz), fast (400 kHz) and extra-fast
    (1000 kHz) bus clock frequencies
- cons
  - TSSOP28 is a 0.65 mm SMD device package, and is not easy to solder
    without professional equipment

my 2 (€)cent

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