SysTick timer on nRF52 fires 1/5 as often as expected

Question

Hi, 
 I'm trying to use the SysTick timer on nRF52 to time some various tasks for debugging. I configured it like so, which I expected would cause SysTick_Handler to be called every 1ms (SystemCoreClock is indeed 64000000): 
 SysTick_Config(SystemCoreClock/1000); 
 However, if I simply increment a counter in the SysTick_Handler and print out the value every 1s (I'm using app_timer to fire a timer every 1000ms), the counter only increments by 200 every second, instead of 1000. 
 Has anyone been able to use SysTick successfully on nRF52? Note that this is with PCA10036 - I looked in the errata but didn't see any issues related to SysTick_Config.

Håkon Alseth · Accepted Answer

Hi, 
 Seems to work fine at my end.
Here's my code-snippet (based on blinky): 
 const uint8_t leds_list[LEDS_NUMBER] = LEDS_LIST;

static uint32_t m_systick_cnt;

void SysTick_Handler(void) {
 m_systick_cnt++;
 if ((m_systick_cnt % 100) == 0)
 nrf_gpio_pin_toggle(BSP_LED_0); 
}

int main(void) 
{
 // Configure LED-pins as outputs.
 LEDS_CONFIGURE(LEDS_MASK);
 SysTick_Config(64000);
 NVIC_EnableIRQ(SysTick_IRQn);
 while (true); 
}
 
 And here's the measured interval, based on 100 ticks:
 
 Cheers,
Håkon

SysTick timer on nRF52 fires 1/5 as often as expected

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