Re: [avr-gcc-list] eeprom usage - Measuring duration of function calls

[Brett Abbott]

Hi

An easy way to measure the duration/length of a function call is to use AVR
Studio.  Set the clock speed correctly and then, using the View->Processor
window combined with appropriately placed breakpoints, you can use the Stopwatch
and cycle counter to measure length.

There are a few limitations with the implementation of some eeprom and SPM
type delays etc but unless you're doing significant eeprom work, this usually
gives a reliable indication of runtimes.

Hope this helps.

Cheers
Brett

Jamie Morken wrote:
> Hi David,
>
>
> > As you can see from the code below, extracted from eeprom.s, the first
> >     
> check is to see if the eeprom is ready, so your code is safe.
> .global _U(eeprom_wb)
>
> Does that code stall if the eeprom isn't ready?  I still haven't learned
> much assembler unfortunately (or was that fortunately?)
>
> I am looking for good way to measure how many clocks a given function call
> or subroutine will take given AVR code.
> Does anyone know of a decent method to do this?  I know AVR is supposedly
> 1MIPS/MHz but with calls to asin(x) etc.
> it seems hard to estimate.
>
> cheers,
> Jamie Morken
>
> _U(eeprom_wb):
> sbic EECR, EEWE
> rjmp _U(eeprom_wb) /* make sure EEPROM is ready */
> #ifdef EEARH
> out EEARH, addr_hi
> #endif
> out EEARL, addr_lo
> out EEDR, val
> in __tmp_reg__, SREG
> cli ; /* no ints between setting EEMWE and EEWE */
> sbi EECR, EEMWE
> sbi EECR, EEWE
> out SREG, __tmp_reg__
> ret
> #undef val
> #endif /* L_eeprom_wb */
>
> The 323 data sheet gives details of EECR and EEWE.
>
> David Breeze
>
>
> > > > Jamie Morken <address@hidden> 30 October 2002 23:59:10 >>>
> > > >           
> > >           
> >           
> Hi,
>
> I read the datasheet for the AVR I am using (atmega323)
> and it gave an eeprom write time of 3.8ms (MAX)
> I tested the below code out and it works fine.
> Is a delay built into the read/write functions or am I just pushing the
> limits of the eeprom?  Is this safe?  I already wrote out the code to
> read/write 16 byte messages to eeprom one byte every 5ms
> (ironically that code doesn't work but the below does)
>
> cheers,
> Jamie Morken
>
>     eeprom_wb(0, 123);
>     eeprom_wb(1, 124);
>     eeprom_wb(2, 125);
>     eeprom_wb(3, 126);
>     eeprom_wb(4, 127);
>     eeprom_wb(5, 128);
>     eeprom_wb(6, 129);
>     eeprom_wb(7, 130);
>
>     printf("eeprom0 = %i\r", eeprom_rb(0));
>     printf("eeprom1 = %i\r", eeprom_rb(1));
>     printf("eeprom2 = %i\r", eeprom_rb(2));
>     printf("eeprom3 = %i\r", eeprom_rb(3));
>     printf("eeprom4 = %i\r", eeprom_rb(4));
>     printf("eeprom5 = %i\r", eeprom_rb(5
> ));
>     printf("eeprom6 = %i\r", eeprom_rb(6));
>     printf("eeprom7 = %i\r", eeprom_rb(7));
>
>
>
>
> avr-gcc-list at http://avr1.org
>
> This e-mail is intended only for the person(s)
> to whom it is addressed.
> If an addressing or transmission error has misdirected
> this e-mail,
> please notify the author by replying to this e-mail.
>
> If you are not the intended recipient
> you must not use, disclose, copy, print
> or rely on this e-mail.
>
> Joy Mining Machinery Ltd may monitor
> outgoing and incoming e-mails and other telecommunications
> on its e-mail and telecommunication systems.
>
>
> avr-gcc-list at http://avr1.org
>
>           
          
-- 
-----------------------------------------------------------------
Brett Abbott, Managing Director, Digital Telemetry Limited
Email: address@hidden
PO Box 24 036 Manners Street, Wellington, New Zealand
Phone +64 (4) 5666-860  Mobile +64 (21) 656-144
------------------- Commercial in confidence --------------------