Arduino Due System_init file

roshancheluva · December 5, 2022, 12:37pm

Hi all,
I am using arduino due in my project.I am using arduino ide 2.0.1 in which i am unable to find hardware folder.i checked arduino installation path also.i want to have a look at system_init file of arduino due.

i am interested to external oscillator selection and PLLA registers.
i want to know how system initialization happens.

pylon · December 5, 2022, 5:15pm

There is no such thing as a system_init file.

Take a look at the datasheet section 22. It describes what happens at boot-up inside the MCU.

westfw · December 5, 2022, 11:20pm

github.com

arduino/ArduinoCore-sam/blob/master/system/CMSIS/Device/ATMEL/sam3xa/source/system_sam3xa.c#L48


      
          
          
#define SYS_CKGR_MOR_KEY_VALUE	CKGR_MOR_KEY(0x37) /* Key to unlock MOR register */
          
          
/* FIXME: should be generated by sock */
          uint32_t SystemCoreClock = CHIP_FREQ_MAINCK_RC_4MHZ;
          
          
/**
           * \brief Setup the microcontroller system.
           * Initialize the System and update the SystemFrequency variable.
           */
          void SystemInit(void)
          {
          	/* Set FWS according to SYS_BOARD_MCKR configuration */
          	EFC0->EEFC_FMR = EEFC_FMR_FWS(4);
          	EFC1->EEFC_FMR = EEFC_FMR_FWS(4);
          
          
	/* Initialize main oscillator */
          	if (!(PMC->CKGR_MOR & CKGR_MOR_MOSCSEL)) {
          		PMC->CKGR_MOR = SYS_CKGR_MOR_KEY_VALUE | SYS_BOARD_OSCOUNT | 
          			                     CKGR_MOR_MOSCRCEN | CKGR_MOR_MOSCXTEN;
          		while (!(PMC->PMC_SR & PMC_SR_MOSCXTS)) {

Reset_handler calls main()
main() calls init() in variants/arduino_due_x/variant.cpp
init() calls SystemInit() (which is defined/recommended by CMSIS)

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Arduino Due System_init file

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