December 2011 Archives

2.3" 7-Segmented Display Prototype

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wire crazy?

This is a 7 digit, 7-segmented display, utilizing several TL constant sink drivers, and the parallax propeller 32 bit, 8-core MCU.  There's a TL driver for every common anode digit; communication is handled via SPI to the cascaded shift registers.  The prototype is 100% wire wrapped, and surprisingly fast!  

Originally we looked into using the maxim 7219, which was a single IC to drive all the segments.  That particular IC is limited to 5v and something like a 60ma sink, which would never drive the 14.4 v, 100ma segments!  There is a way to do it, but the transistor array and/or auxiliary maxim IC's required felt component heavy.  One fun note on the 7219:  it works on POV!

The Propeller MCU was chosen arbitrarily; another project will require these chipsets, so it seemed like a good idea to brush up on 'em.  They are very reliable and incredibly versatile;  parallax sells a kit to make videogame systems out of them!  The compiler crashed on XP, but worked fine on windows 7.  The language itself, is a bit clunky, but the 8 "cogs", and 80mhz speed make up for it!

Lastly, this device will count waterflow, but only once the PCB is back!


Installed and operating, this device is live!  It only needs a darker tint on the glass.
Here's some ktsf video with it.

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justa photo

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This page is an archive of entries from December 2011 listed from newest to oldest.

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