FTM vs PIT vs LPTMR

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FTM vs PIT vs LPTMR

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Contributor III

Hi,

I have seen that Kinetis MCU are equipped with different types of timers: FTM, PIT and LPTMR.

I wanted to know: what are the purposes of each type of timer? What are the differences in terms of performance and jitter time?

Another question regarding FTM. A lower prescaler affects cpu performance (since there are more interrupts) or no?

Thank you in advance!

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Senior Contributor II

In a nutshell:

The PIT is a simple periodic timer. Similar to the SysTick (which is part of the ARM core).

The FTM is a more flexible timer (f == flex) which has multiple channels, input capture, output compare, combined modes, quadrature sampling, ...

The LPTMR is a special timer which can run in low power mode and is able to wake up the system in most modes (if configured as such.

About performance: this all depends on the clock input settings, but I would say they are the same.

Prescaler: this slows down the counting speed of the timer, so useful to keep the timer running at a lower speed. Of course if you have the timer configured to generate interrupts, the interrupts will happe less frequent too. The CPU performance is mostly depending on the core clock speed, and depends what is important for you: if you have too many interupts, of course your CPU won't be able to do much outside of interrupts, if all your time is spent inside the ISR.

I hope this helps,

Erich

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