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mimxrt/hal/pwm_backport: Fix 0 and 65536 edge cases of PWM's duty_u16.
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It should be that:
- duty_u16=0: output low, no pulse
- duty_u16=65536: output high, no pulse

That previously did not apply to all of the three PWM mechanisms of this
port.  This commit fixes it.

Signed-off-by: robert-hh <robert@hammelrath.com>
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@robert-hh @dpgeorge
robert-hh authored and dpgeorge committed Aug 15, 2023
1 parent a9821c0 commit a9a219d
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Showing 2 changed files with 43 additions and 26 deletions.
61 changes: 39 additions & 22 deletions ports/mimxrt/hal/pwm_backport.c
View file
Expand Up @@ -18,10 +18,10 @@
#include "hal/pwm_backport.h"

void PWM_UpdatePwmDutycycle_u16(
PWM_Type *base, pwm_submodule_t subModule, pwm_channels_t pwmSignal, uint16_t dutyCycle, uint16_t Center_u16) {
PWM_Type *base, pwm_submodule_t subModule, pwm_channels_t pwmSignal, uint32_t dutyCycle, uint16_t Center_u16) {
assert((uint16_t)pwmSignal < 2U);
uint16_t pulseCnt = 0, pwmHighPulse = 0;
uint16_t center;
uint32_t pulseCnt = 0, pwmHighPulse = 0;
uint32_t center;

// check and confine bounds for Center_u16
if ((Center_u16 + dutyCycle / 2) >= PWM_FULL_SCALE) {
Expand All @@ -36,11 +36,21 @@ void PWM_UpdatePwmDutycycle_u16(

// Setup the PWM dutycycle of channel A or B
if (pwmSignal == kPWM_PwmA) {
base->SM[subModule].VAL2 = center - pwmHighPulse / 2;
base->SM[subModule].VAL3 = base->SM[subModule].VAL2 + pwmHighPulse;
if (dutyCycle >= 65536) {
base->SM[subModule].VAL2 = 0;
base->SM[subModule].VAL3 = pulseCnt;
} else {
base->SM[subModule].VAL2 = center - pwmHighPulse / 2;
base->SM[subModule].VAL3 = base->SM[subModule].VAL2 + pwmHighPulse;
}
} else {
base->SM[subModule].VAL4 = center - pwmHighPulse / 2;
base->SM[subModule].VAL5 = base->SM[subModule].VAL4 + pwmHighPulse;
if (dutyCycle >= 65536) {
base->SM[subModule].VAL4 = 0;
base->SM[subModule].VAL5 = pulseCnt;
} else {
base->SM[subModule].VAL4 = center - pwmHighPulse / 2;
base->SM[subModule].VAL5 = base->SM[subModule].VAL4 + pwmHighPulse;
}
}
}

Expand Down Expand Up @@ -86,33 +96,33 @@ void PWM_SetupPwm_u16(PWM_Type *base, pwm_submodule_t subModule, pwm_signal_para
}

void PWM_SetupPwmx_u16(PWM_Type *base, pwm_submodule_t subModule,
uint32_t pwmFreq_Hz, uint16_t duty_cycle, uint8_t invert, uint32_t srcClock_Hz) {
uint32_t pwmFreq_Hz, uint32_t duty_cycle, uint8_t invert, uint32_t srcClock_Hz) {

uint32_t pulseCnt;
uint32_t pwmClock;

// Divide the clock by the prescale value
pwmClock = (srcClock_Hz / (1U << ((base->SM[subModule].CTRL & PWM_CTRL_PRSC_MASK) >> PWM_CTRL_PRSC_SHIFT)));
pulseCnt = (pwmClock + (pwmFreq_Hz - 1) / 2) / pwmFreq_Hz;
pulseCnt = (pwmClock + (pwmFreq_Hz - 1) / 2) / pwmFreq_Hz - 1;
base->SM[subModule].INIT = 0;
base->SM[subModule].VAL0 = ((uint32_t)duty_cycle * pulseCnt) / PWM_FULL_SCALE - 1;
base->SM[subModule].VAL1 = pulseCnt - 1;
base->SM[subModule].VAL0 = ((uint32_t)duty_cycle * pulseCnt) / PWM_FULL_SCALE;
base->SM[subModule].VAL1 = pulseCnt;

base->SM[subModule].OCTRL = (base->SM[subModule].OCTRL & ~PWM_OCTRL_POLX_MASK) | PWM_OCTRL_POLX(!invert);

base->OUTEN |= (1U << subModule);
// Switch the output on or off.
if (duty_cycle == 0) {
base->OUTEN &= ~(1U << subModule);
} else {
base->OUTEN |= (1U << subModule);
}
}

#ifdef FSL_FEATURE_SOC_TMR_COUNT
status_t QTMR_SetupPwm_u16(TMR_Type *base, qtmr_channel_selection_t channel, uint32_t pwmFreqHz,
uint16_t dutyCycleU16, bool outputPolarity, uint32_t srcClock_Hz, bool is_init) {
uint32_t dutyCycleU16, bool outputPolarity, uint32_t srcClock_Hz, bool is_init) {
uint32_t periodCount, highCount, lowCount, reg;

if (dutyCycleU16 >= PWM_FULL_SCALE) {
// Invalid dutycycle
return kStatus_Fail;
}

// Counter values to generate a PWM signal
periodCount = ((srcClock_Hz + (pwmFreqHz - 1) / 2) / pwmFreqHz) - 2;
highCount = (periodCount * dutyCycleU16) / PWM_FULL_SCALE;
Expand Down Expand Up @@ -147,11 +157,18 @@ status_t QTMR_SetupPwm_u16(TMR_Type *base, qtmr_channel_selection_t channel, uin

reg = base->CHANNEL[channel].CTRL;
reg &= ~(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));
if (dutyCycleU16 == 0) {
// Clear the output at the next compare
reg |= (TMR_CTRL_LENGTH_MASK | TMR_CTRL_OUTMODE(kQTMR_ClearOnCompare));
} else if (dutyCycleU16 >= 65536) {
// Set the output at the next compare
reg |= (TMR_CTRL_LENGTH_MASK | TMR_CTRL_OUTMODE(kQTMR_SetOnCompare));
} else {
// 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;

return kStatus_Success;
}
#endif // FSL_FEATURE_SOC_TMR_COUNT
8 changes: 4 additions & 4 deletions ports/mimxrt/hal/pwm_backport.h
View file
Expand Up @@ -18,7 +18,7 @@
typedef struct _pwm_signal_param_u16
{
pwm_channels_t pwmChannel; // PWM channel being configured; PWM A or PWM B
uint16_t dutyCycle_u16; // PWM pulse width, value should be between 0 to 65536
uint32_t dutyCycle_u16; // PWM pulse width, value should be between 0 to 65536
uint16_t Center_u16; // Center of the pulse, value should be between 0 to 65536
pwm_level_select_t level; // PWM output active level select */
uint16_t deadtimeValue; // The deadtime value; only used if channel pair is operating in complementary mode
Expand All @@ -27,17 +27,17 @@ typedef struct _pwm_signal_param_u16
#define PWM_FULL_SCALE (65536UL)

void PWM_UpdatePwmDutycycle_u16(PWM_Type *base, pwm_submodule_t subModule,
pwm_channels_t pwmSignal, uint16_t dutyCycle, uint16_t center);
pwm_channels_t pwmSignal, uint32_t dutyCycle, uint16_t center);

void PWM_SetupPwm_u16(PWM_Type *base, pwm_submodule_t subModule, pwm_signal_param_u16_t *chnlParams,
uint32_t pwmFreq_Hz, uint32_t srcClock_Hz, bool output_enable);

void PWM_SetupPwmx_u16(PWM_Type *base, pwm_submodule_t subModule,
uint32_t pwmFreq_Hz, uint16_t duty_cycle, uint8_t invert, uint32_t srcClock_Hz);
uint32_t pwmFreq_Hz, uint32_t duty_cycle, uint8_t invert, uint32_t srcClock_Hz);

#ifdef FSL_FEATURE_SOC_TMR_COUNT
status_t QTMR_SetupPwm_u16(TMR_Type *base, qtmr_channel_selection_t channel, uint32_t pwmFreqHz,
uint16_t dutyCycleU16, bool outputPolarity, uint32_t srcClock_Hz, bool is_init);
uint32_t dutyCycleU16, bool outputPolarity, uint32_t srcClock_Hz, bool is_init);
#endif // FSL_FEATURE_SOC_TMR_COUNT

#endif // PWM_BACKPORT_H

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