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AVR, external clock

U

Umpa

Hello,

I have got AVR ATmega16.

I`m developing an application
which should receive data from
UART.
I would like to conntec external
oscilator of 11059200 Hz.
I connected it to XTAL and set
fuse "ext. clock", but processor
doesn`t work.

What to do to make my processor
working with external oscilator
and using it for UART?

Umpa.
 
A

Anders

What type of XTAL is it ?
What input pins are you using ?

/Anders
 
A

Anders

OK
Have you connected 2 capacitors to the XTAL ?
22-33pF is mostly used, look in the datasheet.
/ Anders
 
U

Umpa

Have you connected 2 capacitors to the XTAL ?
22-33pF is mostly used, look in the datasheet.

Yes. Two capacitors of 27pF connected to XTAL1
and XTAL2 and GND.

Test:

I connected 8MHz oscilator, set fuse XTAL3-8MHz.
It works.

I connected 11MHz oscilator, set fuse XTAL3-8MHz.
Doesn`t work.

I connected 11MHz oscilator, set fuse XTAL3-8MHz,
changed state of !CKOPT.
Doesn`t work

I tried a few 11MHz oscilators.

If I use oscilator slower than 8MHz there are fuses that
cover it (XTAL3-8, XTAL...)

But my oscilator is 11MHz. Atmel`s manual says that
we should change CKOPT for oscilators faster than 8MHz.
But it doesn`t help.

Umpa.
 
U

Umpa

Is it at MEGA16 or a MEGA16L ?

I have got ATmega16. Without "L".
Any idea about my problem ?

Umpa.
 
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