Help me understand SAM9260's clocks

Jul 19, 2010 0 Replies

I've started programming AT91SAM9260 and some things are not clear to me.



At first, sam-ba was giving me problems

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so I created a small win32 app to mimic sam-ba.



On reset, sam9260 sends "RomBOOT>" and then listens to commands. I then issue some commands to write to internal SRAM and then execute it. All that works.



Speed is what interests me now, so I set the led, then clear it, in a loop. There are some 80 sets/resets and one jump, to minimize jump's execution time effect.



The instruction are: str r3, [r2, #-203] ; 0xcb // clear str r3, [r2, #-207] ; 0xcf // set



I have a 18.432 MHz clock, and this what I use for PLL:



#define PLLA_SETTINGS 0x2060BF09



or, to write it in a more readable way:



#define DIVA 9 #define PLLACOUNT 63 #define OUTA 2 #define MULA 96 #define PLLA_SETTINGS (1


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