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Topic: Overclocking the Arduino DUE (Read 425 times) previous topic - next topic

janost

Thought I try some DUE overclocking just for the fun of it :)
So I tried some different PLL MUL/DIV settings.

It seem that 120MHz is max what the SAM3X8E Cortex M3 chip will run.
This is not because of the flash read speed but because of the internal SRAM and that has no waitstate setting.

So at 114MHz it runs stable with the original 4FWS setting (20MHz AHB bus-speed).

That is 136% overclocking without any problems.

Code: [Select]

#define SYS_BOARD_PLLAR (CKGR_PLLAR_ONE | CKGR_PLLAR_MULA(18UL) | CKGR_PLLAR_PLLACOUNT(0x3fUL) | CKGR_PLLAR_DIVA(1UL))
#define SYS_BOARD_MCKR ( PMC_MCKR_PRES_CLK_2 | PMC_MCKR_CSS_PLLA_CLK)
       
/* Set FWS according to SYS_BOARD_MCKR configuration */
EFC0->EEFC_FMR = EEFC_FMR_FWS(4); //4 waitstate flash access
EFC1->EEFC_FMR = EEFC_FMR_FWS(4);

/* Initialize PLLA to 114MHz */
PMC->CKGR_PLLAR = SYS_BOARD_PLLAR;
while (!(PMC->PMC_SR & PMC_SR_LOCKA)) {}

PMC->PMC_MCKR = SYS_BOARD_MCKR;
while (!(PMC->PMC_SR & PMC_SR_MCKRDY)) {}

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