2 - 3 digit display eficiently
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Posts: 46,084
can some one point me in the direction of literature on prouducing a
3 digit display with out using 20 + pins, id like to use as few as
possible, even if it cost me 10$ for anohter chip for the bs2 to
power,,,,, man please dont block this , but i also wish it to work
on 16f84's or at best maybe a way to learn both, im compleatly
oblivous to "driver" chips, multiplexing, and any thing but the good
old 7 + 1 method per digit plus dec point, id apreacite any thing
you guys can throw me, just looking to make designing a display
feasable, rather then 8 i/o per digit
im not asking how, im asking where is the material to learn it. this
has to be the second most asked question on here
3 digit display with out using 20 + pins, id like to use as few as
possible, even if it cost me 10$ for anohter chip for the bs2 to
power,,,,, man please dont block this , but i also wish it to work
on 16f84's or at best maybe a way to learn both, im compleatly
oblivous to "driver" chips, multiplexing, and any thing but the good
old 7 + 1 method per digit plus dec point, id apreacite any thing
you guys can throw me, just looking to make designing a display
feasable, rather then 8 i/o per digit
im not asking how, im asking where is the material to learn it. this
has to be the second most asked question on here
Comments
Parallel the inputs of the 4511s (A,B,C,D) together, and use the "STORE"
pins to select the display.
A flow would go something like this
Output your digits
Enable Display 1
Output your digits
Enable Display 2
Output your digits
Enable Display 3
This only takes 7 wires (ABCD and Display 1 2 3 enable) and works rather
well...for me at least.
Kris
>can some one point me in the direction of literature on prouducing a
>3 digit display with out using 20 + pins, id like to use as few as
>possible, even if it cost me 10$ for anohter chip for the bs2 to
>power,,,,, man please dont block this , but i also wish it to work
>on 16f84's or at best maybe a way to learn both, im compleatly
>oblivous to "driver" chips, multiplexing, and any thing but the good
>old 7 + 1 method per digit plus dec point, id apreacite any thing
>you guys can throw me, just looking to make designing a display
>feasable, rather then 8 i/o per digit
>im not asking how, im asking where is the material to learn it. this
>has to be the second most asked question on here
>
>
>
>
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1) Use a MAX7219 or similar multiplexer
2) Use three 74HC595 shift-registers for your segment outputs
#1 gives you programmatic control over LED brightness, will cost more
than #2. Both use just a few pins and can be ported to virtually any
microcontroller.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: jutsuju [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=FMjLF9aplFf6L0uoMoVDppOLyqL4MGQ_YzeCdTKAgDQNxk9Irl5MouEBmOkgUh36rkasQoVkm8smp8t_]xsavior38@h...[/url
Sent: Saturday, April 17, 2004 12:40 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] 2 - 3 digit display eficiently
can some one point me in the direction of literature on prouducing a
3 digit display with out using 20 + pins, id like to use as few as
possible, even if it cost me 10$ for anohter chip for the bs2 to
power,,,,, man please dont block this , but i also wish it to work
on 16f84's or at best maybe a way to learn both, im compleatly
oblivous to "driver" chips, multiplexing, and any thing but the good
old 7 + 1 method per digit plus dec point, id apreacite any thing
you guys can throw me, just looking to make designing a display
feasable, rather then 8 i/o per digit
im not asking how, im asking where is the material to learn it. this
has to be the second most asked question on here
It sounds like your three digit display has 24 pins (7 segments + dp). You
can use a 74hc595 shift register and the basic stamp. This configuration will
consume 3 stamp pins and you can control 24 outputs with the 3 pins, and 3 595
ic's.
Look at experiments 23 and 23b. There is the example on how to hook up the IC
and example code.
http://www.parallax.com/html_pages/downloads/sw/sw.asp
ken
====================
can some one point me in the direction of literature on prouducing a
3 digit display with out using 20 + pins, id like to use as few as
possible, even if it cost me 10$ for anohter chip for the bs2 to
power,,,,, man please dont block this , but i also wish it to work
on 16f84's or at best maybe a way to learn both, im compleatly
oblivous to "driver" chips, multiplexing, and any thing but the good
old 7 + 1 method per digit plus dec point, id apreacite any thing
you guys can throw me, just looking to make designing a display
feasable, rather then 8 i/o per digit
im not asking how, im asking where is the material to learn it. this
has to be the second most asked question on here
[noparse][[/noparse]Non-text portions of this message have been removed]
works with what you already know. Basically,
the '595 is a serial-in, parallel out shift
register with LOTS of current drive available.
Thus, you wire one '595 to each LED character,
with appropriate current limiting resistors. You
then send your LED segment data from the BS2 to
the '595 using the 'SHIFTOUT' command. This takes
three pins of the BS2 -- AND, you can 'party-line'
all your '595, so 3 pins of the BS2 can update
any number of LED digits -- except you only get
26 bytes of data in the BS2. Still, for 4 or 8
LED digits, this is very practical -- one byte
per digit.
You don't have to worry then about multiplexing.
Check out the 'Nuts&Volts' area of the Parallax
site for more details.
--- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
wrote:
> There's a couple of simple ways to go:
>
> 1) Use a MAX7219 or similar multiplexer
> 2) Use three 74HC595 shift-registers for your segment outputs
>
> #1 gives you programmatic control over LED brightness, will cost
more
> than #2. Both use just a few pins and can be ported to virtually
any
> microcontroller.
>
> -- Jon Williams
> -- Applications Engineer, Parallax
> -- Dallas Office
>
>
>
Original Message
> From: jutsuju [noparse][[/noparse]mailto:xsavior38@h...]
> Sent: Saturday, April 17, 2004 12:40 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] 2 - 3 digit display eficiently
>
>
> can some one point me in the direction of literature on prouducing
a
> 3 digit display with out using 20 + pins, id like to use as few as
> possible, even if it cost me 10$ for anohter chip for the bs2 to
> power,,,,, man please dont block this , but i also wish it to work
> on 16f84's or at best maybe a way to learn both, im compleatly
> oblivous to "driver" chips, multiplexing, and any thing but the
good
> old 7 + 1 method per digit plus dec point, id apreacite any thing
> you guys can throw me, just looking to make designing a display
> feasable, rather then 8 i/o per digit
> im not asking how, im asking where is the material to learn it.
this
> has to be the second most asked question on here