RE: [AVR-Chat] help required abt program memory
2008-04-02 by Tim Mitchell
John Samperi wrote: > At 12:51 AM 2/04/2008, you wrote: >> The SPM instruction can address the first 64kBytes of program memory, >> according to the datasheet. > > I believe this is the case however I have based my comments on the > following. p242 M644 data sheet under Application Section. > > The Application section can never store any Boot Loader code since > the SPM instruction is disabled when executed from the Application > section. > M16 and M128 say the same thing so I expect you are right. I am not sure what Mark means by "SPM can address the first 64Kbytes of memory". On all the devices I have looked at, SPM can address all of the flash memory using RAMPZ to control address above 16 bits. But as you say it does nothing unless you are executing it from the bootloader section of flash (and have set up all the register bits to enable SPM) -- Tim Mitchell tim@sabretechnology.co.uk http://www.sabretechnology.co.uk Sabre Technology (Hull) Ltd, 3a Newlands Science Park, Hull HU6 7TQ Registered in England and Wales no.3131504 t:01482 801003 f:01482 801078