Re: [avr-gcc-list] Doubts on ATmega128(L) clock speed

[Graham Davies]

Leonardo B. Oliveira wrote:

"I have some doubts about ATmega128's clock speed I'd much appreciate
comments on them."

 

This list is for discussion of GCC for the AVR, not general AVR problems.

"... difference between ATmega128 and ATmega128L ..."

You have it more-or-less right.  It's all in the data sheet.  The 128 needs a 5 V supply and will run up to 16 MHz.  THe 128L is happy with lower voltages but will only run up to 8 MHz.

 

"... to specify clock speed the only thing I need is to set up
properly the option "-DF_CPU"?"

 

This specifies the clock speed to the compiler.  Getting the MCU to run at you chosen clock speed is something you have to take care of yourself by programming fuses and connecting up the appropriate crystal, capacitors or whatever.

"... is it possible to change clock speed at running time? ..."

 

I don't think so.

 

Graham.