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

[Bob Paddock]

On Sun, Feb 17, 2013 at 5:28 PM, Rick Mann <address@hidden> wrote:
> I'm looking through the docs for the XMEGA A3U parts, and I can't find which 
> pins are the RTC xtal pins. I can tell it's PORT E, but I don't see which 
> specific pins.
>
> Does someone know where this is documented, and/or what the pins are?

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."

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