Kinetis MicrocontrollersのトピックFree running timer on K82

Free running timer on K82

EugeneHiihtaja — Thu, 16 Aug 2018 07:30:10 GMT

Hello !

For FreeRTOS profiling I need 32bit timer what is increment with clock 10-100kHz.

LPTIMERx resolution is not so good and timers used for other purposes.

From other side it is not so visible on K82 spec other simply timers. Only FTM/PTM like.

Could you suggest what kind of peripheral timer can be programmed as simply running 32bit timer counter ?

Thank you !

Eugene

jingpan — Thu, 16 Aug 2018 09:57:36 GMT

Hi Eugene,

PIT(periodic interrupt timer) is a good choice. Details please find in rm. There is also examples in SDK.

Regards,

Jing

EugeneHiihtaja — Thu, 16 Aug 2018 12:58:38 GMT

Hi Jing !

PIT timer has resolution 32 bit and BusClock is only clock source for it.

If bus clock 48Mhz, it count full loop in ~ 89s.

What should be enough for short term measurements. FreeRTOS supports only 32bit counter only for keep track of task execution time.

May be have sense to use chained timer and use high 32bit and reload low timer every 10 us.

Regards,

Eugene

jingpan — Fri, 17 Aug 2018 03:05:20 GMT

Hi,

Yes, you can use chain mode. There is examples in the reference manual.

Regards,

Jing

EugeneHiihtaja — Fri, 17 Aug 2018 07:39:17 GMT

Hi Jing !

Yes it work as expected. I have chained Timer1 and Timer 0. And 1 count resolution - 100 Khz is enough for by used inside FreeRTOS fro profiling.

I try to configure PIT timers via embedded ConfigTools and even chaining is mentioned, it can't be set.

Regards,

Eugene