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SubjectMystery Solved Reply to this message
Posted bysellenoff
Posted on10/15/04 07:01 PM



Ok - I'm pretty sure I solved this mystery now..

The cpu is an Atmel AT91 series which has internal ram mapped in memory ~0x300000 at boot.. The code can then write to an internal register to re-map the ram to Page 0. I watched the code, and it does just this, eventually executing code back from address 0 (which is now executing from ram)...

On the 2nd time round now, the MOV commands make sense, as R0-R3 were populated prior to the RAM remapping, so the code in this 2nd time through is now saving those registers.

At least, that's my theory.. :)




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Entire Thread
Subject  Posted byPosted On
*ARM7 Reset question  sellenoff10/13/04 11:23 AM
.*Re: ARM7 Reset question  ElSemi10/14/04 07:57 AM
..*Re: ARM7 Reset question  sellenoff10/15/04 01:00 AM
....Mystery Solved  sellenoff10/15/04 07:01 PM
....*Re: Mystery Solved  Videoman10/16/04 03:43 PM
.....*Re: Mystery Solved  sellenoff11/02/04 02:57 AM
......*Re: Mystery Solved  Videoman11/25/04 08:22 AM
.....*Re: Mystery Solved  R. Belmont10/31/04 04:35 PM
.....*Re: Mystery Solved  sellenoff10/31/04 00:38 AM