topic Re: perform us wait using lptmr driver in S32K

perform us wait using lptmr driver

elb1 — Mon, 10 Jun 2024 12:26:19 GMT

Hello i am using lptmr project example from sdk (lptmr_periodic_interrupt) for s32k142, and i want to use for freertos project.
i am not using interrupts which means i don't want it to go to the interrupt once the configured value has past.
What i want is to perform a microsecond delay, how can i do that using the functions that are in lptmr_driver.c file ?

Re: perform us wait using lptmr driver

elb1 — Tue, 11 Jun 2024 15:51:23 GMT

i added this function:

void LPTMR_DRV_DelayUs()

{

LPTMR_DRV_StartCounter(INST_LPTMR1);

while (!(LPTMR_DRV_GetCompareFlag(INST_LPTMR1)));

LPTMR_DRV_ClearCompareFlag(INST_LPTMR1);

LPTMR_DRV_StopCounter(INST_LPTMR1);

}

so when i first initilize the driver i do this:

lptmr_config_t lpTmr1_config0 =

{

.workMode = LPTMR_WORKMODE_TIMER,

.dmaRequest = false,

.interruptEnable = false,

.freeRun = false,

.compareValue = 100,

.counterUnits = LPTMR_COUNTER_UNITS_MICROSECONDS,

.clockSelect = LPTMR_CLOCKSOURCE_SIRCDIV2,

.prescaler = LPTMR_PRESCALE_2,

.bypassPrescaler = false,

.pinSelect = LPTMR_PINSELECT_TRGMUX,

.pinPolarity = LPTMR_PINPOLARITY_RISING,

};

LPTMR_DRV_Init(INST_LPTMR1, &lpTmr1_config0, false);

And then during the task running i do this:

(void)gpio_write(&gpio, false);

LPTMR_DRV_DelayUs();

(void)gpio_write(&gpio, true);

LPTMR_DRV_DelayUs();

I was supposed to get 100us delay between the gpio toggling, but instead i get 108us, and the 8 will always be there (ex. if i configure the timer for 50us i will get 58us etc)

Re: perform us wait using lptmr driver

_Leo_ — Thu, 13 Jun 2024 21:44:15 GMT

Thank you so much for your interest in our products and for using our community.

I noticed that you have another similar case, so I will follow up on this last one that I mention.

Have a nice day!