The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: Jonathan Kirwan
Subject: Re: 8bit binary to BCD?
X-Newsreader: Forte Agent 1.92/32.572
NNTP-Posting-Date: Tue, 29 Oct 2002 10:50:56 GMT
Organization: AT&T Broadband
Date: Tue, 29 Oct 2002 10:50:56 GMT
On Mon, 28 Oct 2002 20:33:04 GMT, Ash
>haven't studied digital engineering for almost a decade so the memory is a bit rusty :)
>Anyways, thing is I got an 8 bit paralell binary databus I need to hook up to 3 7-segment
>displays. Strobing the bus ic you get bit 1-2-4-8-16-32-64-128 high and I want to convert it
>to BCD to use a simple bcd-led driver ic (something like the 4511).
>The bus signals are constant high or low when strobed so speed/memory is not essential -
>I simply want to translate the binary to display the corresponding numbers on the display
>when I apply the strobe...
>Anyone have any ideas? I thoght of 74184 but it's not been manufactured for some time,
>I'm not asking for a complete solution - but I sure need a few pointers in the right direction
I know you've said you have difficulty programming micros, but
here's another suggestion:
Look at Micrel's MM5450 controller (it is a replacement part for
National's MM5450.) Unicorn Electronics claims to have these
available in 1's for US$4.49. (Radio Shack used to sell MM5450
and MM5451 as part numbers 900-6842 and 900-6843 -- no longer,
though.) It includes 34 segment drivers with a minimum of 15mA
sink capability per segment. It also includes a brightness
control which can be adjusted via duty cycle. Serially loaded
from micro, via clock and data. 40DIP or 44PLCC.
If the micro was able to observe your data bus properly, it
would only need the 9 data bus pins plus two lines for clock and
data plus one more for brightness adjust (if desired.) That
could be satisfied with a PIC16F630 or PIC16F676, or larger.
(The PIC16F676 is priced at US$2.28 in 1's at Digikey, though
they don't yet have stock on that newer part.)
But this would be only a few parts and capable of constant drive
of all segments, allowing easy control of brightness and
extension to more segments (or the use of extra segments for
multiplexing, if needed.) The micro could support display in
hex, as well as decimal, if desired. Etc.
The EPROM suggestions will need several chips and some kind of
LED drive buffering which the Micrel mentioned above provides.
If you can tolerate lower average current into the LED segments,
a single micro with 22 I/Os would suffice for the whole project,
using multiplexing and lowering the average duty cycle to meet
the micro's continuous power specs. A 28DIP would suffice and
the PIC16F72 is available from Digikey at US$3.45 which would
Perhaps an incentive to learn some coding??
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup