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Systick timer problem of KEA8

Question asked by Charl Zou on Jul 27, 2020
Latest reply on Aug 6, 2020 by Alexis Andalon

I have a strange problem with kea8.It 

  • My core clock is FEI mode ,48Mhz,and bus clock is 24Mhz.And configure code as below:

ICS_C2 = 0x20; 
ICS_C1 = 0x04; 
while ((ICS_S & ICS_S_LOCK_MASK) == 0); 
SIM_CLKDIV = 0x01100000;
ICS_C2 = 0x00; 


  • I use systick to make a 1ms interrupt.And configure code as below:

/*!Comment:Set the systick timer as 1ms.*/
SYST_RVR = 48000u;

/*!Comment:set systick source clock.*/
SYST_CSR |= (1 << 2);


/*!Comment:Enable systick.*/
SYST_CSR |= (1 << 0);

/*!Comment:Enable interrupt.*/
SYST_CSR |= (1 << 1);


void SysTick_Handler(void)

   /*!Comment:Catch the first time entering interrupt.*/
    GPIOA_PTOR |= (1 << 13u);


  • The GPIO is correctly configured.When I power on the device ,It delay about 120ms to enter the first interrupt handle function "SysTick_Handler".If I use PIT module instead of systick,the delay time will decreace to 20~30ms.

I want to fix the delay time of systick timer?I use other chip like kea64 FEE mode with systick timer will not have this problem,it delay 20~30ms,too.

I want to know the minimal time to initialize clock FEI and FEE mode(KEA8 KEA64) .