Hello,
I am following along an example project called "evkmimxrt1060_flexio3_pwm".
I am able to output a 90% duty cycle square wave in the range of 48MHz . I am suppose to output a 1.04kHz wave with a duty cycle of 90%.
Here is settings from the example project:
/* Select USB1 PLL (480 MHz) as flexio clock source */
#define FLEXIO_CLOCK_SELECT (3U)
/* Clock pre divider for flexio clock source */
#define FLEXIO_CLOCK_PRE_DIVIDER (4U)
/* Clock divider for flexio clock source */
#define FLEXIO_CLOCK_DIVIDER (7U)
#define DEMO_FLEXIO_CLOCK_FREQUENCY \
(CLOCK_GetFreq(kCLOCK_Usb1PllClk) / (FLEXIO_CLOCK_PRE_DIVIDER + 1U) / (FLEXIO_CLOCK_DIVIDER + 1U))
/* FLEXIO output PWM frequency */
#define DEMO_FLEXIO_FREQUENCY (48000U)
#define FLEXIO_MAX_FREQUENCY (DEMO_FLEXIO_CLOCK_FREQUENCY / 2U)
#define FLEXIO_MIN_FREQUENCY (DEMO_FLEXIO_CLOCK_FREQUENCY / 256U)
Here is the timer config that is in the example:
/* Configure the timer DEMO_FLEXIO_TIMER_CH for generating PWM */
fxioTimerConfig.triggerSelect = FLEXIO_TIMER_TRIGGER_SEL_SHIFTnSTAT(0U);
fxioTimerConfig.triggerSource = kFLEXIO_TimerTriggerSourceInternal;
fxioTimerConfig.triggerPolarity = kFLEXIO_TimerTriggerPolarityActiveLow;
fxioTimerConfig.pinConfig = kFLEXIO_PinConfigOutput;
fxioTimerConfig.pinPolarity = kFLEXIO_PinActiveHigh;
fxioTimerConfig.pinSelect = DEMO_FLEXIO_OUTPUTPIN; /* Set pwm output */
fxioTimerConfig.timerMode = kFLEXIO_TimerModeDisabled;
fxioTimerConfig.timerOutput = kFLEXIO_TimerOutputOneNotAffectedByReset;
fxioTimerConfig.timerDecrement = kFLEXIO_TimerDecSrcOnFlexIOClockShiftTimerOutput;
fxioTimerConfig.timerDisable = kFLEXIO_TimerDisableNever;
fxioTimerConfig.timerEnable = kFLEXIO_TimerEnabledAlways;
fxioTimerConfig.timerReset = kFLEXIO_TimerResetNever;
fxioTimerConfig.timerStart = kFLEXIO_TimerStartBitDisabled;
fxioTimerConfig.timerStop = kFLEXIO_TimerStopBitDisabled;
I have tried to change the clock dividers and also flexio clock select. I still can't get the frequency down below 1kHz. The lowest I have been able to go is 1.4kHz. This involved changing the FLEXIO_CLOCK_SELECT to 0U (which I think connects to PLL4 based on CCM_CDCDR_FLEXIO_CLK_SEL_SHIFT, which is 24MHz).
From what I have been able to find, it seems that the flexio clock I am using is derived from the pll3_sw_clk which is then derived from the Usb1PllClk. I can't find how they are configured though, or a way to connect the flexio to a different clock source that will get me below 1Khz.
If anyone can help me that would be appreciated. I am still new and learning!
