[simpits-tech] Solid-state LED matrix help

[Cris Harrison]

On 7/19/2011 9:46 PM, Roberto Waltman wrote:
> dabigboy at cox.net wrote:
>> Awesome, how did you find these?!?
> Once upon a time, I was looking for a display for a
> calculator. A search using an HP part number brought me to
> Avago.
>
>> Question though: how would this offer an advantage over the QDSP-2007?>  I'm assuming easier interfacing, would it reduce the
> number of components I need for interfacing this to, say, an
> Arduino?
>
Unfortunately you picked a display that is categorized as 'dumb'. That 
means basically what, and or where do you want to put your effort.  Just 
because this chip has a serial port, and internal shit registers,  means 
that you have to to ALL the work in code. Now what does that mean?

   1. You have to design and build the interface to the chip.
   2. You have to write the interface library to the chip.
   3. You have to write the ascii to chip encoder.

Now lets look a two other approaches.

    * Smart Display Modules. you need 1.
    * Smart Display Driver - Dumb Display = wire interface between the
      to and your done.

I prefer the last two approaches: and the second one is even better... 
Lets look at  a Max6955 this beast has a I2C interface (nice), and can 
drive 16 7-segment, 8 14 or 16-segment or 128 discrete LEDs, or a 
combination of display types.
Moral of this story: Design, Design, Design. Maybe change your Display 
Modules.
Enjoy
Cris H.
phoenixcomm.net/~phnx2000/sim
phoenixcomm.wordpress.com/projects/nav-cdu/


> Without knowing the details of the QDSP-2007, a
> "traditional" LED matrix is just that, a LED matrix.
> You need to provide drivers for each row/column/segment, and
> refresh the data continuously.
>
> The Avago chips have internal drivers and latches. You write
> the data you want displayed only once, (or only when it
> changes,) and the display's built-in circuitry takes care of
> the rest.  The interface is one bit in into a big shift
> register plus a few control lines.
> If the microcontroller uses the same voltage (say, 3.3V) you
> don't need anything more than routing the lines between
> controller and display. (Except, maybe, a few pull up or
> down resistors)
>
> --
> Roberto Waltman
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