Alt-BEAM Archive
Message #06543
To: beam@sgiblab.sgi.com
From: Sean Rigter rigter@cafe.net
Date: Fri, 08 Oct 1999 19:03:17 -0700
Subject: [alt-beam] Animated LCD name tag
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THE ANIMATED LCD NAME TAG
The attached ANIMLCD schematic shows how it's done : It flashes the words ROBO and then DOC for about 1 second each Any other
2 words within the limitations of the seven segment display can be shown. I have build one and it works great!
Instead of the two bicore lines driving the static type LCD name tags, the animated LCD adds the classic bicore "reversing"
circuit to generate 4 lines for controlling the LCD. How Beamish can it get?
The rule for displaying any two messages is as follows:
1. segments which are "on" for both words are connected to the ON line
2. segments which are "off" for both words are connected to the OFF line
3. segments "on" in the first word and "off" in the second are connected to ON'
4. segments "off" in the first word and "on" in the second are connected to OFF'
5. the backplane terminal is connected to the OFF line
Sounds simple but it takes a bit to work out all the segment connections. You can check the connections for ROBO/DOC to see
how they follow the rule.
You may be interested in the reason for all the switching waveforms. It is that LCD segments must not be subjected to a DC
voltage or else they will die. That is why the "on" segments and backplane are driven "out of phase" by the two bicore
outputs which generates a 30 Hz AC voltage equal to 3V RMS between the "on" segments and the backplane. An "off" segment is
connected to the same bicore output as the backplane and therefore the voltage between an "off" segment and the backplane is
0V. The Bicore "reverser" switches the polarity of some segments to be "in or out of phase" with the backplane signal
thereby turning those segments either on or off under control of the second bicore. The two messages alternate at about 0.5
Hz rate displaying each for about 1 second.
Next : more messages and a low power LCD display for bicore/microcore diagnostics!
enjoy
wilf
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Attachment: ANIMLCD.gif
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6544 Fri, 08 Oct 1999 19:07:54 -0700 [alt-beam] Re: lcd name plates.... beam@sgiblab.sgi.com Sean Rigter A good idea and posted just before my "diagnostic indicator" suggestion. Guess
you get the credit! Any other applications? Anyone?
regards
wilf
SG wrote:
> YA KNOW,
> since these things take so little juice,
> you could concievably hook it up
> to a bicore's inverters that are ALREADY in use,
> Like a HEAD.
> when head turns right, word "right" comes on
> and "left" for... well you know.
> don't know what use it'd be other than kinda
> neato show-off kinda thingy fer your desk.
>
> At 06:09 PM 10/8/99 -0700, you wrote:
> >Hi Sparky
> >
> >The following letters can be intelligibly displayed
> >A,b,C/c,d,E,F,G/g,H/h,i, J,L,o,P,S,t,U/u or V/v, y, Z.
> >and the numbers 0-9 with the 5 and S doubling up.
> >There are other letters but at the risk of confusion
> >with numerals.
> >
> >There are also (rare) 16 segment displays that can
> >display the whole alphabet and can be similarly
> >controlled with bicores
> >
> >Finally, there true multiline character displays that
> >can (with some difficulty) also be BEAMerized!
> >
> >regards
> >
> >wilf
> >
> >SG wrote:
> >
> >> hmmm... wunder how you'd make a "T"
> >> :)
> >>
> >> really kewl though!
> >> -Sparky
> >>
> >> At 12:45 PM 10/8/99 -0700, you wrote:
> >> >74HC240 or HCT240 pin 1,19,20 = +3V, pin 4,6,8,11,13,15 = 0V
> >> >Bicore caps between pin 17,18 and between 2,3. Resistor between pin 2 and
> >> 17. Pin 3 is connected to the "on" segments and pin
> >> >18 is connected to the backplane (BP) and "off" segments. LCD terminals
> >> DP means decimal point or collons. The LCD pinout is
> >> >used for illustration only.
> >> >
> >> >regards
> >> >
> >> >wilf
> >> >
> >> >Michael Hirtle wrote:
> >> >
> >> >> Hi Wilf the nly problem i have with this is where do u place the power
> >> supply leads?
> >> >>
> >> >> Sean Rigter wrote:
> >> >>
> >> >> > (Formatted this time and with the GIF attached).
> >> >> >
> >> >> > Ahh! Great idea Ian! Seven segment type numerical LCDs say from a
> >> broken digital clock or calculator. I
> >> >
> >> >
> >
> >
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