Re: [AVR-Chat] Stack Pointer - documentation conflict?
2006-04-05 by Henry Carl Ott
At 06:03 PM 4/5/2006, you wrote: >The newer avr parts init the stack at ramend. Atmel has a tendency to copy >and paste their data sheets, and these kind of conflicts creep in. > The 0x60 is a bit of a giveaway, I'm pretty sure ram STARTS at 0x100 on >most of the newer chips with an expanded i/o space. > > >Hmm.. Do we know which chips? >I don't like exceptions. :( It's neat, but they COULD make this behaviour >retroactive through all chips. I can't see why anyone would be bothered. >If you're writing code that depends on SP=0000 on boot, that's pretty scary! Perhaps not an exception, just a new feature with the new silicon. But I'd guess it's on a chip by chip basis. The mega 48/88/168s that I'm playing with these days set the SP to RAMEND (just tested on a m168 hardware to be sure). The mega8s always used to set it to 0x00. I don't really trust it myself, and I'll be setting the SP manually until I really really need those last couple of program words. One does wish the documentation was more consistent. carl -------------------------------------------------------- Henry Carl Ott N2RVQ http://users.rcn.com/carlott/ --------------------------------------------------------