diff options
| -rw-r--r-- | ports/atmel-samd/common-hal/pulseio/PWMOut.c | 11 | ||||
| -rw-r--r-- | ports/atmel-samd/common-hal/pulseio/PWMOut.h | 1 |
2 files changed, 10 insertions, 2 deletions
diff --git a/ports/atmel-samd/common-hal/pulseio/PWMOut.c b/ports/atmel-samd/common-hal/pulseio/PWMOut.c index 6dcace21f..92305161f 100644 --- a/ports/atmel-samd/common-hal/pulseio/PWMOut.c +++ b/ports/atmel-samd/common-hal/pulseio/PWMOut.c @@ -135,6 +135,7 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self, bool variable_frequency) { self->pin = pin; self->variable_frequency = variable_frequency; + self->duty_cycle = duty; if (pin->timer[0].index >= TC_INST_NUM && pin->timer[1].index >= TCC_INST_NUM @@ -322,6 +323,13 @@ void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) { } extern void common_hal_pulseio_pwmout_set_duty_cycle(pulseio_pwmout_obj_t* self, uint16_t duty) { + // Store the unadjusted duty cycle. It turns out the the process of adjusting and calucating + // the duty cycle here and reading it back is lossy - the value will decay over time. + // Track it here so that if frequency is changed we can use this value to recalcuate the + // proper duty cycle. + // See https://github.com/adafruit/circuitpython/issues/2086 for more details + self->duty_cycle = duty; + const pin_timer_t* t = self->timer; if (t->is_tc) { uint16_t adjusted_duty = tc_periods[t->index] * duty / 0xffff; @@ -415,7 +423,6 @@ void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, break; } } - uint16_t old_duty = common_hal_pulseio_pwmout_get_duty_cycle(self); if (t->is_tc) { Tc* tc = tc_insts[t->index]; uint8_t old_divisor = tc->COUNT16.CTRLA.bit.PRESCALER; @@ -450,7 +457,7 @@ void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, #endif } - common_hal_pulseio_pwmout_set_duty_cycle(self, old_duty); + common_hal_pulseio_pwmout_set_duty_cycle(self, self->duty_cycle); } uint32_t common_hal_pulseio_pwmout_get_frequency(pulseio_pwmout_obj_t* self) { diff --git a/ports/atmel-samd/common-hal/pulseio/PWMOut.h b/ports/atmel-samd/common-hal/pulseio/PWMOut.h index eef653bcb..09abda819 100644 --- a/ports/atmel-samd/common-hal/pulseio/PWMOut.h +++ b/ports/atmel-samd/common-hal/pulseio/PWMOut.h @@ -36,6 +36,7 @@ typedef struct { const mcu_pin_obj_t *pin; const pin_timer_t* timer; bool variable_frequency; + uint16_t duty_cycle; } pulseio_pwmout_obj_t; void pwmout_reset(void); |