Re: Driving red/green LED from high/low/tri-state output
- From: jasen <jasen@xxxxxxxxxxx>
- Date: 7 Mar 2007 07:09:45 GMT
On 2007-03-06, Joel Kolstad <JKolstad71HatesSpam@xxxxxxxxx> wrote:
I have a battery charger IC that tells you the IC's function via a "staus" pin
output that's one of three states: Hi-Z when a battery isn't present or is too
hot or cold to charge, high when it's actively charging, and low when it's
finished charging. I'd like to convert this signal to drive two LEDs, red and
green (they're actually both in one package, but all 4 pins are accessible).
The idea being that Hi-Z=>off, high->red (charging), and low->green
(finished). What's the easiest way to do this?
So far I haven't thought up
any easy schemes... and my first -- now obviously dumb -- approach of
connecting the pin to the two LEDs connected back to back -- with current
limiting resistors -- doesn't work in that a Hi-Z output just causes both LEDs
to glow dimly!
you're so close to the answer....
.-------------------------------------------------------------.
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`-------------------------------------------------------------'
green
LED
in ---+--|<----+--[RX]--- +v
| |
| |
+--->|---+--[RX]--- gnd
red
LED
--
Bye.
Jasen
.
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