topic Re: timer in Kinetis Microcontrollers

timer

deepaksimon — Thu, 04 Jun 2015 09:40:49 GMT

hi, i am a beginner in microcontroller programing.i have a freescale kl25z board.now i am trying to interface anseconds?? ultrasound sensor with this board.how can i check the time delay using a timer in microseconds??please give me a detailed answer with sampple programs if possible

Re: timer

xiangjun_rong — Fri, 05 Jun 2015 01:40:21 GMT

Hi, Deepak,

Frankly speaking, I do not know the signal pattern of the ultrasound sensor, anyway,If your ultrasound sensor can generate square-waveform signal, you can use FTM module to test the time of two edges of the square-waveform signal, the FTM has capture function, which can detect the edge of external signal and trigger an interrupt.

If the ultrasound sensor can not generate the square-waveform signal, I think you can use Timer to generate interrupt, for example Timer can generate an interrupt in 1mS interval, in the ISR, you can increase a variable, you can get the time by reading the variable.

Hope it can help you

Xiangjun rong

Re: timer

adriancano — Fri, 05 Jun 2015 02:09:56 GMT

Hi Deepak Simon,

You will probably find the next post from colleague Erich Styger very useful.

Tutorial: Ultrasonic Ranging with the Freedom Board | MCU on Eclipse

Hope this information can help you

Best Regards,
Adrian Sanchez Cano
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Re: timer

deepaksimon — Fri, 05 Jun 2015 04:19:20 GMT

Dear Adrian Sanchez Cano, Thank you for your help.I am using a software called coocox. i this i need to configure the timer manually.How can i do this? can you help me??

Re: timer

deepaksimon — Fri, 05 Jun 2015 04:20:32 GMT

thank you

Re: timer

xiangjun_rong — Mon, 08 Jun 2015 03:42:13 GMT

Hi, Deepak,

In the end, I know you want to know the delay time, if it is the case, you can use either the system tick timer(SysTick) module or the TPM to finish it.

I think you can use the following code to get the delay based on TPM0 module. The delayTimerTick is the delay tick number , the tick is the frequency of FLL output clock.

XiangJun Rong

static int i = 0;

void delay(void);

void TPM_Init(void);

uint16_t getTPMCounter(void);

void ResetTPM(void);

int main(void)

{

uint16_t delayTimerTick;

/* Write your code here */

/* This for loop should be replaced. By default this loop allows a single stepping. */

TPM_Init();

ResetTPM();

delay();

delayTimerTick=getTPMCounter();

__asm("nop"); //set a break point here

for (;;) {

i++;

}

/* Never leave main */

return 0;

}

void TPM_Init(void)

{

SIM_SCGC6|=0x03000000; //enable FTM0 and FTM0 module clock

SIM_SCGC5|=0x3E00;

SIM_SOPT2|=0x1000000; //select TPMSRC clock source as MCGIRCLK clock

TPM0_CONF=0x00; //set up BDM in 11

TPM0_MOD=0xFFFF;

TPM0_C0SC=0x14; //FTM output signal toggle when the FTM counter matches with //C0V registrer

TPM0_C0V=500;

TPM0_SC=0x08; // system clock driving, dividing by 1

}

void ResetTPM(void)

{

TPM0_CNT=0x00;

}

uint16_t getTPMCounter(void)

{

uint16_t temp;

temp=TPM0_CNT;

return temp;

}

void delay(void)

{

uint16_t delayCounter;

for(delayCounter=0; delayCounter<1000; delayCounter++)

{

__asm("nop");

}