LPC546xx SysTick Priority

[ming_liao1]

Hi,

In SDK examples, SysTick IRQ priority is set at 7 (Lowest priority), and the reset value of all NVIC IRQs' priority is 0 (Highest priority). If to keep the reset value of NVIC IRQs' priority and to change the SysTick IRQ priority from 7 to 0, then SysTick IRQ is in processing, and the SysTick IRQ won't be delay when a request is from any NVIC IRQ, right?

Thanks.

[xiangjun_rong · Accepted solution]

Hi,

You are right, if the priority of systick interrupt source is set up to zero, it is of the highest interrupt priority for configurable interrupt source, if the other interrupt sources are of non-zero priority in register, the systick interrupt will be handled immediately because the cortex-m4 supports nested interrupt.

You can use the function to set up the interrupt priority:

NVIC_SetPriority (SysTick_IRQn, 0x00);

For detailed inf, pls refer to the 2.3.2 Exception types in the User guide of cortex-M4.

Hope it can help you

BR

XiangJun Rong