AVR-Chat

See attached word doc have added individual LED resistors to adjust
current.

This is to meet the original requirement of 2 LED's on one port pin.

_______________________________________
 
Roy Hopkins
Tauranga
New Zealand
_______________________________________
 
> -----Original Message-----
> From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On
Behalf
> Of Peter Gargano
> Sent: Saturday, 4 March 2006 5:30 a.m.
> To: AVR-Chat@yahoogroups.com
> Subject: Re: [AVR-Chat] Bi-Colour LED coontrol with one pin?
> 
> Roy wrote:
> > See attached WORD file of the Switcher CAD III plot of the circuit
> below.
> 
> Thanks Roy for the analysis info.
> 
> > *From:*  *Russell Shaw
> 
> Thanks Russell for the original circuit.
> 
> One problem of course is getting enough current to drive the LEDs to a
> reasonable brightness. This is mostly due to having them run from what
> is effectively a 2.5 Volt rail. Differences in brightness between red
> and green LEDs because of different operating voltages is also
> exacerbated.
> 
> I'm leaning towards using a shift register like the 74HC595 and
> sending it data via the SPI - in my current design this allows me to
> control up to 8 LEDs with just the original extra pin!  And it takes
> about the same PCB real estate too.
> 
> Peter

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