Question

Assume a 4.094 mhz clock is used as the system clock and the systick selects it as the clock. What should the systick_load register be in order to generate a systick interrupt every mili second?

Answer 1

The load value for interrupts every one milliseconds is

$\begin{aligned}&\mathrm{val}=1 \times 10^{-3} \times 4.094 \times 10^6 \\&\Rightarrow \mathrm{val}=4094\end{aligned}$

The load value for interrupts every millisecond is

$\begin{aligned}&\mathrm{val}=1 \times 10^{-6} \times 4.094 \times 10^6 \\&\Rightarrow \mathrm{val}=4.094\end{aligned}$

However, we can only load integer values, therefore we apply

$\Rightarrow v a l \approx 4$

When the delay is 1 ms, it is accurate, but when the delay is 1 us, it is a little bit less. We are unable to provide an accurate 1 us delay interrupt because this requires a fractional value was calculated.

What does a SysTick timer do?

• The systick timer has an auto reload and a 24-bit countdown timer.
• An RTOS scheduler typically uses it to provide a periodic interrupt.
• The Cortex-M CPU clock is used as the default clock source for the systick timer.

To learn about more tape timer, visit:

brainly.com/question/27798869

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