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On 7/19/2011 9:46 PM, Roberto Waltman wrote:
<blockquote cite="mid:4E264170.9080807@rwaltman.com" type="cite">
<pre wrap=""><a class="moz-txt-link-abbreviated" href="mailto:dabigboy@cox.net">dabigboy@cox.net</a> wrote:
</pre>
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<pre wrap="">Awesome, how did you find these?!?
</pre>
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<pre wrap="">
Once upon a time, I was looking for a display for a
calculator. A search using an HP part number brought me to
Avago.
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<pre wrap="">Question though: how would this offer an advantage over the QDSP-2007? > I'm assuming easier interfacing, would it reduce the
</pre>
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<pre wrap="">number of components I need for interfacing this to, say, an
Arduino?
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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? <br>
<ol>
<li>You have to design and build the interface to the chip.</li>
<li>You have to write the interface library to the chip. <br>
</li>
<li>You have to write the ascii to chip encoder.</li>
</ol>
Now lets look a two other approaches. <br>
<ul>
<li>Smart Display Modules. you need 1.</li>
<li>Smart Display Driver - Dumb Display = wire interface between
the to and your done.</li>
</ul>
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 <span class="Apple-style-span"
style="border-collapse: separate; color: rgb(0, 0, 0);
font-family: 'Times New Roman'; font-style: normal; font-variant:
normal; font-weight: normal; letter-spacing: normal; line-height:
normal; orphans: 2; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px; font-size:
medium;"><span class="Apple-style-span" style="">16 7-segment, 8
14 or 16-segment or 128 discrete LEDs, or a combination of
display types. <br>
Moral of this story: Design, Design, Design. Maybe change your
Display Modules. <br>
Enjoy <br>
Cris H.<br>
phoenixcomm.net/~phnx2000/sim<br>
phoenixcomm.wordpress.com/projects/nav-cdu/<br>
<br>
<br>
</span></span>
<blockquote cite="mid:4E264170.9080807@rwaltman.com" type="cite">
<pre wrap="">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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