diff options
-rw-r--r-- | nuttx/arch/arm/src/stm32/stm32_pwm.c | 77 |
1 files changed, 53 insertions, 24 deletions
diff --git a/nuttx/arch/arm/src/stm32/stm32_pwm.c b/nuttx/arch/arm/src/stm32/stm32_pwm.c index 68d935aa2..54b15529c 100644 --- a/nuttx/arch/arm/src/stm32/stm32_pwm.c +++ b/nuttx/arch/arm/src/stm32/stm32_pwm.c @@ -141,7 +141,8 @@ struct stm32_pwmtimer_s uint8_t timtype; /* See the TIMTYPE_* definitions */ #ifdef CONFIG_PWM_PULSECOUNT uint8_t irq; /* Timer update IRQ */ - uint8_t rcr; /* Previous pulse count */ + uint8_t prev; /* The previous value of the RCR (pre-loaded) */ + uint8_t curr; /* The current value of the RCR (pre-loaded) */ uint32_t count; /* Remaining pluse count */ #endif uint32_t base; /* The base address of the timer */ @@ -694,8 +695,31 @@ static int pwm_timer(FAR struct stm32_pwmtimer_s *priv, #ifdef CONFIG_PWM_PULSECOUNT if (info->count > 0) { - uint16_t count = (uint16_t)pwm_pulsecount(info->count) - 1; - pwm_putreg(priv, STM32_ATIM_RCR_OFFSET, count); + /* Save the remining count and the number of counts that will have + * elapsed on the first interrupt. + */ + + /* If the first interrupt occurs at the end end of the first + * repition count, then the count will be the same as the RCR + * value. + */ + + priv->prev = pwm_pulsecount(info->count); + pwm_putreg(priv, STM32_ATIM_RCR_OFFSET, (uint16_t)priv->prev - 1); + + /* Generate an update event to reload the prescaler. This should + * preload the RCR into active repetition counter. + */ + + pwm_putreg(priv, STM32_GTIM_EGR_OFFSET, ATIM_EGR_UG); + + /* Now set the value of the RCR that will be loaded on the next + * update event. + */ + + priv->count = info->count; + priv->curr = pwm_pulsecount(info->count - priv->prev); + pwm_putreg(priv, STM32_ATIM_RCR_OFFSET, (uint16_t)priv->curr - 1); } /* Otherwise, just clear the repitition counter */ @@ -703,14 +727,22 @@ static int pwm_timer(FAR struct stm32_pwmtimer_s *priv, else #endif { + /* Set the repeition counter to zero */ + pwm_putreg(priv, STM32_ATIM_RCR_OFFSET, 0); + + /* Generate an update event to reload the prescaler */ + + pwm_putreg(priv, STM32_GTIM_EGR_OFFSET, ATIM_EGR_UG); } } + else #endif + { + /* Generate an update event to reload the prescaler (all timers) */ - /* Generate an update event to reload the prescaler (all timers) */ - - pwm_putreg(priv, STM32_GTIM_EGR_OFFSET, ATIM_EGR_UG); + pwm_putreg(priv, STM32_GTIM_EGR_OFFSET, ATIM_EGR_UG); + } /* Handle channel specific setup */ @@ -894,14 +926,6 @@ static int pwm_timer(FAR struct stm32_pwmtimer_s *priv, pwm_putreg(priv, STM32_GTIM_SR_OFFSET, 0); pwm_putreg(priv, STM32_GTIM_DIER_OFFSET, ATIM_DIER_UIE); - /* Save the remining count and the number of counts that will have - * elapsed on the first interrupt. Since the first interrupt will - * occur immediately, that count will be zero. - */ - - priv->rcr = 0; - priv->count =info->count; - /* Enable the timer */ cr1 |= GTIM_CR1_CEN; @@ -956,7 +980,7 @@ static int pwm_interrupt(struct stm32_pwmtimer_s *priv) * since the last interrupt. */ - if (priv->count <= priv->rcr) + if (priv->count <= priv->prev) { /* We are finished. Turn off the mast output to stop the output as * quickly as possible. @@ -976,27 +1000,32 @@ static int pwm_interrupt(struct stm32_pwmtimer_s *priv) priv->handle = NULL; priv->count = 0; - priv->rcr = 0; + priv->prev = 0; + priv->curr = 0; } else { /* Decrement the count of pulses remaining using the number of - * pulses generated since the last interrupt. This will be the - * same as the current RCR value *except* on the first interrupt. + * pulses generated since the last interrupt. */ - priv->count -= priv->rcr; + priv->count -= priv->prev; - /* Calculate and set the next RCR value */ + /* Set up the next RCR. Set 'prev' to the value of the RCR that + * was loaded when the update occurred (just before this interrupt) + * and set 'curr' to the current value of the RCR register (which + * will bet loaded on the next update event). + */ - priv->rcr = pwm_pulsecount(priv->count); - pwm_putreg(priv, STM32_ATIM_RCR_OFFSET, (uint16_t)priv->rcr - 1); + priv->prev = priv->curr; + priv->curr = pwm_pulsecount(priv->count - priv->prev); + pwm_putreg(priv, STM32_ATIM_RCR_OFFSET, (uint16_t)priv->curr - 1); } /* Now all of the time critical stuff is done so we can do some debug output */ - pwmllvdbg("Update interrupt SR: %04x RCR: %d count: %d\n", - regval, priv->rcr, priv->count); + pwmllvdbg("Update interrupt SR: %04x prev: %d curr: %d count: %d\n", + regval, priv->prev, priv->curr, priv->count); return OK; } |