Which Timer

[Tabulous]

I'm i right to assume

#define STM32_ST_USE_TIMER 2

means the OS will use GPT2 for the OS tick ? and thus this cannot be used by the user application ?

[RoccoMarco]

Yes you are right. It could be change with TIM 5 which is another 32-bit timer. Or you can reduce the timer resolution to 16 in chconf.h (not suggested)

Code: Select all

/**
 * @brief   System time counter resolution.
 * @note    Allowed values are 16 or 32 bits.
 */
#define CH_CFG_ST_RESOLUTION                16

[Giovanni]

Correct but it does not use the GPT driver, there is a special ST (SysTick) driver that supports variable intervals.

Giovanni

[neums]

Hi,
when the ST driver uses (for example) STMs SysTick Timer, why do i have to define

Code: Select all

#define STM32_ST_USE_TIMER 2

?

There is just one Systick Timer

Thanks

[Giovanni]

Hi,

The ST driver can use both the SysTick and the TIM timers, SysTick is used in ticked mode regardless that setting, TIMs are used in tickless mode and you can select which one to use.

Giovanni

[neums]

Ticked mode is if

Code: Select all

OSAL_ST_MODE == OSAL_ST_MODE_PERIODIC

and tickless if

Code: Select all

OSAL_ST_MODE == OSAL_ST_MODE_FREERUNNING

?

[Giovanni]

Correct.

Giovanni