[Icc-avr] 32 KHz Crystal start up problems

[John Baraclough]

Hi Patrick,

Have you got any external capacitors? The description of the 
Timer/Counter Oscillator on page 46 says that the connections should be 
as Figure 21. This shows external capacitors, but the text gives no 
indication of what value should be used. Try a few pf and see what happens.

All the best for now,
John

Patrick Fletcher-Jones wrote:
> Hope this finds you all well.
>
> I'm just wondering if anyone has had problems with the 32KHx crystal not
> starting up on the Atmel processors.
>
> I've use them many times before and never had a problem, but on this latest
> project they quite often don't seem to start up. I have to touch one of the
> legs with a probe etc.. Then they run fine.
>
> I'm using the mega1280, 3.3Volts.
>
> I've had problems a long time ago (PACS days Andy) with the wrong crystal
> capacitance on a very low power RTCC, but did not thing the AVRs were that
> sensitive. I've just used a watch crystal from Farnell.
>
> Thanks in advance for any suggestions,
>
> Patrick 
>
>
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