topic Re: Programmable Delay Block in Kinetis Microcontrollers

Programmable Delay Block

john71 — Wed, 13 Jun 2018 06:10:42 GMT

Can I use Programmable Delay Block (PDB) as a delay mechanism?
Say instead of

for (i = 0; i < delay; i++) ;

If so -is there some example?

Re: Programmable Delay Block

mjbcswitzerland — Wed, 13 Jun 2018 13:02:00 GMT

Evgeny

The PDB is useful for controlling sampling points but not for software delays.

See example in chapter 3 of http://www.utasker.com/docs/uTasker/uTaskerADC.pdf

For accurate software wait type delays you can use the SYSTICK. Here is the method used in the uTasker project to wait a defined number of microseconds.

extern void fnDelayLoop(unsigned long ulDelay_us)
{
    #define CORE_US (CORE_CLOCK/1000000)                                 // the number of core clocks in a us
    register unsigned long ulPresentSystick;
    register unsigned long ulMatch;
    register unsigned long _ulDelay_us = ulDelay_us;                     // ensure that the compiler puts the variable in a register rather than work with it on the stack
    if (_ulDelay_us == 0) {                                              // minimum delay is 1us
        _ulDelay_us = 1;
    }
    (void)SYSTICK_CSR;                                                   // clear the SysTick reload flag
    ulMatch = (SYSTICK_CURRENT - CORE_US);                               // next 1us match value (SysTick counts down)
    do {
        while ((ulPresentSystick = SYSTICK_CURRENT) > ulMatch) {         // wait until a us period has expired
            if ((SYSTICK_CSR & SYSTICK_COUNTFLAG) != 0) {                // if we missed a reload
                (void)SYSTICK_CSR;
                break;                                                   // assume a us period expired
            }
        }
        ulMatch = (ulPresentSystick - CORE_US);
    } while (--_ulDelay_us != 0);
}

This assumes that the SYSTICK is running but allows it to be shared with a SYSTICK periodic interrupt.

Regards

Mark

Re: Programmable Delay Block

john71 — Wed, 13 Jun 2018 13:09:07 GMT

Thank you.

Re: Programmable Delay Block

Robin_Shen — Fri, 15 Jun 2018 03:22:24 GMT

Hi Evgeny Erenburg,

You can use Programmable Delay Block (PDB) as a delay mechanism.

Please download the MCUXpresso SDK_2.4.0 and find the delay_interrupt example.

All these hardware timer is able to achieve it.

Best Regards,

Robin

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Re: Programmable Delay Block

john71 — Fri, 15 Jun 2018 05:33:19 GMT

Thank you. MCUXpresso dosen't support my MK10FN1M0VLQ12.

Re: Programmable Delay Block

Robin_Shen — Fri, 15 Jun 2018 09:23:56 GMT

Unfortunately, at the moment there is no plan to support this part number with SDK libraries.

Best Regards,

Robin