Kinetis Design Studio中的主题 Re: Using FlexTimer to create microsecond delay

Using FlexTimer to create microsecond delay

keyboardcowboy — Fri, 26 Feb 2021 19:44:28 GMT

I am trying to use one of the FlexTimer modules to create a microsecond delay function using Kinetis Design Studio (KDS SDK) and K64 MCU. My initialization code

FTM_DRV_Init(FSL_FLEXTIMER1,&DelayTimer_InitConfig); FTM_DRV_SetClock(FSL_FLEXTIMER1, kClock_source_FTM_SystemClk, kFtmDividedBy1); FTM_DRV_SetTimeOverflowIntCmd(FSL_FLEXTIMER1,false); FTM_DRV_SetFaultIntCmd(FSL_FLEXTIMER1,false);

And the actual delay function looks like

void delay_us(uint16_t au16_us) { FTM_Type *ftmBase = g_ftmBase[FSL_FLEXTIMER1]; FTM_DRV_CounterStart(FSL_FLEXTIMER1, kCounting_FTM_UP, 0x0,0xFFFF, false); while (FTM_HAL_GetCounter(ftmBase) < (au16_us*11)){}; FTM_DRV_CounterStop(FSL_FLEXTIMER1); FTM_HAL_SetCounter(ftmBase, 0); }

I am not able to get any delays when I call the function like

delay_us(500);

My system clock is 20Mhz

What am I doing wrong?. Can anyone help me out?

Re: Using FlexTimer to create microsecond delay

danielchen — Tue, 02 Mar 2021 03:08:13 GMT

Hi @keyboardcowboy

There is FTM timer demo in SDK. It demonstrates how to use the FTM driver. It sets up the FTM hardware block to trigger an interrupt every 1 millisecond.

SDK_2.9.0_FRDM-K64F\boards\frdmk64f\driver_examples\ftm\timer

You can download the SDK from below link

https://mcuxpresso.nxp.com/en/welcome

Regards

Daniel

Re: Using FlexTimer to create microsecond delay

keyboardcowboy — Tue, 02 Mar 2021 15:47:58 GMT

Hi @danielchen

Thank you. Is it not possible to do this without interrupt?. I don't want to use interrupts for this delay routine. Just want execution to stop for the amount of delay specified in microseconds