From: "Roger Hamlett"
Subject: Re: ? Binary to BCD conversion chip ?
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Date: Thu, 5 Dec 2002 10:15:53 -0000
NNTP-Posting-Date: Thu, 05 Dec 2002 10:26:42 GMT
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"Yi-Zen Chu; Yiren Qu" <""y i z e n \"@ u c l i n k 4 . b e r k e l e y . e
d u> wrote in message news:mUeF9.151366$NH2.11112@sccrnsc01...
> Hello everyone,
> Does anyone know if there's any IC chip commercially available that can
> convert a 4 (or 8 bit) number to BCD? Where can I buy it? I tried
> looking up on the Net but only found 74185, which seemed to be
> Thanks for the help!
Others have allready suggested using an EPROM, but it is also worth asking
what sort of speed is required, and whether there are any other functions
that need to be done?. One reason these chips have disappeared, is that this
sort of decoding can be done so easily in a microprocessor now, and in many
cases with less power consumption. For example, the same logic as the 74185,
could be generated in a basic PIC, that in the UK, costs about £1.50 in one
off quantities. Using it's own internal oscillator (so no need for a
crystal), the conversion could be coded in about half a dozen instructions
(using a look up table), giving a latency of perhaps 10uSec. This sort of
chip, consumes uA, so provided the speed requirement is slow, could well be
an economic solution. If the total conversion required is more complex
(perhaps feeding seven segment displays), this type of choice becomes even
better, since a slightly larger chip could be programmed to directly drive
the digit segments, removing the need for a seperate BCD to seven segment
converter. I also have to ask where the binary patterns are coming from?. In
many cases, applications that used this type of chip in the past, can now be
done using other products, that give BCD directly.
You mention coding just 4 or 8 bits 'sections', which is very easy to do in
a 'look up table' solution (this is the EPROM that has allready been
suggested), the only problem with this solution, is finding small ROMs these