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Re: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644
From: |
Preston Wilson |
Subject: |
Re: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644 |
Date: |
Fri, 21 Mar 2008 19:02:32 -0400 |
User-agent: |
Microsoft-Entourage/11.4.0.080122 |
"Weddington, Eric" wrote:
>> I have an Atmega644 in the DIP package that I could breadboard with a
>> quick LED blinking circuit. Since I'm doing this in Linux,
>> I'm not sure
>> what is a good value to assign to F_CPU, and yes, I did check the 376
>> page data sheet, but I am still not sure how to calculate
>> this value --
>> sorry.
>>
>
> Hi Bob,
>
> F_CPU is just a defined value which is your CPU Frequency in Hertz. This
> symbol can then be used in your application if you need it.
Take a look at the section of the datasheet that explains the default clock
source, which is a subsection of the System Clock chapter or wherever the
ATmega644's datasheet describes the CKSEL, SUT, and CKDIV8 fuse values.
Examples of how to set F_CPU:
System Clock Frequency F_CPU
125 kHz 125000
1 MHz 1000000
7.3728 MHz 7372800
avr-libc's delay.h also uses F_CPU.
-Preston
- [avr-chat] New Programmer, Small Program, F_CPU for Atmega644, Robert L Cochran, 2008/03/21
- RE: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644, Weddington, Eric, 2008/03/21
- Re: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644,
Preston Wilson <=
- Re: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644, Joerg Wunsch, 2008/03/22
- Re: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644, Robert L Cochran, 2008/03/23
- Re: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644, Joerg Wunsch, 2008/03/24
- Message not available
- Re: [avr-chat] AVR power supply current, Robert L Cochran, 2008/03/24