See attached WORD file of the Switcher CAD III plot of the circuit below.
_______________________________________
Roy Hopkins
22 Grenada Street
Tauranga
New Zealand
_______________________________________
-----Original Message-----
From: AVR-Chat@yahoogroups.com
[mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Russell Shaw
Sent: Thursday, 2 March 2006 7:44 p.m.
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] Bi-Colour
LED coontrol with one pin?
Peter Gargano wrote:
> I can't figure this out simply. I'm sure
there is a simple solution
> tho'. Chip is the Mega-168 that I want to add
an extra function to.
>
> Assume I have either a two or three pin
bi-colour LED (ie. either back
> to back LEDs with two pins, or two LEDs with
a common pin).
>
> I have a single pin on an AVR processor that
can either be LOW, HIGH,
> or Tri-state.
>
> I want to drive the LEDs either both OFF, one
on, or the other on, but
> NOT both on.
>
> SO, I have three states the pin can be in,
and three states for the
> LED to be in.
>
;
+5VCC
;
--+----------+--
;
| |
AVR ;
|c NPN >
---+
LEDs ;
\|b__ < 10k
|
+-->|---+
/| | >
|pin |
| 220ohms |e
| |
+-----+
+-----\/\/\-------+ +----+
|
|
|
|e | |
|
+--|<---+
\|b__| >
---+
/| < 10k
;
|c PNP >
;
| |
;
----+----------+---- GND
--
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