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Re: [avr-chat] TSOC1 & 2 pins on XMEGA A3U?

From: Rick Mann
Subject: Re: [avr-chat] TSOC1 & 2 pins on XMEGA A3U?
Date: Sun, 17 Feb 2013 14:57:29 -0800

On Feb 17, 2013, at 14:54 , Bob Paddock <address@hidden> wrote:

> Same as you, could not find in the datasheet.
> By the coloring of the pins PORTE.6 and PORTE.7 look like a good guess.
> Designing by 'guess' is great, does make you wonder who writes these
> datasheets. :-(
> Also be aware of this with XMega RTC:
> I was told by Atmel that you can not drive the RTC input with an
> external oscillator,
> unless you want to add power wasting bias network.
> Kills the whole idea of using a  temperature compensated 400 nA 32 kHz osc.
> Here is the official line via my FAE:
> "The optimal solution for the oscillator is to have TOSC2 at 1.2V and
> let TOSC1 oscillate around this level. A small swing, ±0.2V, is better
> than a large swing.  Full swing (GND to VCC) is not guaranteed to be
> stable."

Wow. So many kinds of awful in that. I use the SPI port on Port E, which uses 
PE6 & 7. And as to the stability and power consumption, that's just horrible.

Good thing this particular design doesn't need an RTC. I just like leaving room 
for one in all designs.


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