Whack !! Ouch !! Gotta stop whacking my forehead like that. Ok, that's
easy. So if my load measurement is say 45000 then I need the first (
65535/30 = ~2184, 45000/2184 = ~21 ) 21 LEDS lit. Shift out 9 zeros then 21
ones. I guess I was making a mountain out of a mole hill !!


Regarding the Borland Forum, I enjoyed being a part of that community and I
missed it when it changed.  The members of this list seem to share the same
spirit and I'm glad to be a part of it.

Eric

-----Original Message-----
From:   Gerhard Fiedler [SMTP:lists@HOME.COM]
Sent:   Monday, February 22, 1999 2:09 AM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        Re: How to display 0 - 100% on an LED bar

At 23:41 02/21/99 -0600, Eric Oliver wrote:
> Several years ago, I belonged to the Borland C++ forum on CIS. It was
>there that I learned to program.  Over time I was able to give back to
that
>group.

that was really a good forum, many years ago! :)  or is that :( ?

>I would like to pose a question. I'm not really planning to use this
>algorithm at this time, but I just bought three LED chips from Radio
Shack.
>I'm sure most of you know the item.  Each chip consists of ten LEDs in a
>bar configuration. You can mount any number of them side by side to form a
>chain of bars. I used them to test my PIC hooked up to some 595s.
>
>But I was thinking that they could be used to convey information in the
>form of a bar. With values ranging from 0% to 100%. For instance, if you
>chained three chips, the first green, the next yellow and the last one was
>red. Say you were monitoring spindle load on a machine.  As the load
>progresses from 0% to ~33% the green LEDs would light in succession, as it
>moved past 33% through ~66% the yellow LEDs would begin to light and so
on.
>
>So what I can't figure out is how to translate the load ( in the previous
>example ) to the bit representation needed to shift to the 595s.  Just as
>an example, let's say the spindle load is measured and the result would be
>between 0 and 65535.  Now, we would need 30 bits to control all 30 LEDs.
>How would you go about converting the load to the 30 bit number ?

you don't need a 30bit number just because you want to drive a 30led bar :)
all you need is a number from 0 to 30, which boils down to a simple
division, if your representation is linear. 0->0%->no led, 65535->100%->all
(30) leds. that's 30 intervals for 65535, hence each interval
(corresponding to one led more) is 65535/30... you divide your load by this
number, and get the number of leds to switch on.

ge