QTMR PWM Example

DFaulkner — Thu, 17 Feb 2022 21:15:00 GMT

MCUXpresso IDE v11.4.1 [Build 6260] [2021-09-15]

SDK_2.x_MIMXRT1160-EVK: Version 2.1.0

EVK1160 PCB

I am trying to get my PWM started using QTIMER2_TIMER0 for GPIO_DISP_B1_01 (D13). Here is my code setup from the driver example:

int main(void)
{
uint8_t i = 0;
qtmr_config_t qtmrConfig;

/* Board pin, clock, debug console init */
BOARD_ConfigMPU();
BOARD_InitPins();
BOARD_BootClockRUN();
BOARD_InitDebugConsole();

/*!
* brief Sets up Quad timer module for PWM signal output.
*
* The function initializes the timer module according to the parameters passed in by the user. The
* function also sets up the value compare registers to match the PWM signal requirements.
*
* param base Quad Timer peripheral base address
* param channel Quad Timer channel number
* param pwmFreqHz PWM signal frequency in Hz
* param dutyCyclePercent PWM pulse width, value should be between 0 to 100
* 0=inactive signal(0% duty cycle)...
* 100=active signal (100% duty cycle)
* param outputPolarity true: invert polarity of the output signal, false: no inversion
* param srcClock_Hz Main counter clock in Hz.
*
* return Returns an error if there was error setting up the signal.
*/
status_t QTMR_SetupPwm(TMR_Type *base,
qtmr_channel_selection_t channel,
uint32_t pwmFreqHz,
uint8_t dutyCyclePercent,
bool outputPolarity,
uint32_t srcClock_Hz)
{
uint32_t periodCount, highCount, lowCount;
uint16_t reg;
status_t status;

if (dutyCyclePercent <= 100U)
{
/* Set OFLAG pin for output mode and force out a low on the pin */
base->CHANNEL[channel].SCTRL |= (TMR_SCTRL_FORCE_MASK | TMR_SCTRL_OEN_MASK);

/* Counter values to generate a PWM signal */
periodCount = srcClock_Hz / pwmFreqHz;
highCount = periodCount * dutyCyclePercent / 100U;
lowCount = periodCount - highCount;

if (highCount > 0U)
{
highCount -= 1U;
}
if (lowCount > 0U)
{
lowCount -= 1U;
}

/* This should not be a 16-bit overflow value. If it is, change to a larger divider for clock source. */
assert(highCount <= 0xFFFFU);
assert(lowCount <= 0xFFFFU);

/* Setup the compare registers for PWM output */
base->CHANNEL[channel].COMP1 = (uint16_t)lowCount;
base->CHANNEL[channel].COMP2 = (uint16_t)highCount;

/* Setup the pre-load registers for PWM output */
base->CHANNEL[channel].CMPLD1 = (uint16_t)lowCount;
base->CHANNEL[channel].CMPLD2 = (uint16_t)highCount;

reg = base->CHANNEL[channel].CSCTRL;
/* Setup the compare load control for COMP1 and COMP2.
* Load COMP1 when CSCTRL[TCF2] is asserted, load COMP2 when CSCTRL[TCF1] is asserted
*/
reg &= (uint16_t)(~(TMR_CSCTRL_CL1_MASK | TMR_CSCTRL_CL2_MASK));
reg |= (TMR_CSCTRL_CL1(kQTMR_LoadOnComp2) | TMR_CSCTRL_CL2(kQTMR_LoadOnComp1));
base->CHANNEL[channel].CSCTRL = reg;

if (outputPolarity)
{
/* Invert the polarity */
base->CHANNEL[channel].SCTRL |= TMR_SCTRL_OPS_MASK;
}
else
{
/* True polarity, no inversion */
base->CHANNEL[channel].SCTRL &= ~(uint16_t)TMR_SCTRL_OPS_MASK;
}

reg = base->CHANNEL[channel].CTRL;
reg &= ~(uint16_t)TMR_CTRL_OUTMODE_MASK;
/* Count until compare value is reached and re-initialize the counter, toggle OFLAG output
* using alternating compare register
*/
reg |= (TMR_CTRL_LENGTH_MASK | TMR_CTRL_OUTMODE(kQTMR_ToggleOnAltCompareReg));
base->CHANNEL[channel].CTRL = reg;

status = kStatus_Success;
}
else
{
/* Invalid dutycycle */
status = kStatus_Fail;
}

return status;
}

}

My question is for this enum:

status_t QTMR_SetupPwm(TMR_Type *base,
qtmr_channel_selection_t channel,
uint32_t pwmFreqHz,
uint8_t dutyCyclePercent,
bool outputPolarity,
uint32_t srcClock_Hz)

Where should these parameters be defined? Are they only initialized or do they have a default value somewhere that I am missing?

Re: QTMR PWM Example

kerryzhou — Tue, 01 Mar 2022 07:07:23 GMT

Hi @DFaulkner ,

Not all the pins can be used as the QTIMER2_TIMER0 PWM pin, please check the IO chapter:

When you select the related pin, you also need to configure it in the pin_mux.c, please check the current SDK code for QTIMER.

SDK_2_11_0_MIMXRT1160-EVK\boards\evkmimxrt1160\driver_examples\qtmr

Wish it helps you!

Best Regards,

Kerry

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