fix off-by-one PWM top issue

Author: dhalbert

ports/raspberrypi/common-hal/pwmio/PWMOut.c

@@ -164,19 +164,20 @@ void common_hal_pwmio_pwmout_deinit(pwmio_pwmout_obj_t* self) {
 
 extern void common_hal_pwmio_pwmout_set_duty_cycle(pwmio_pwmout_obj_t* self, uint16_t duty) {
  self->duty_cycle = duty;
- uint16_t actual_duty = duty * self->top / ((1 << 16) - 1);
+ // Do arithmetic in 32 bits to prevent overflow.
+ uint16_t actual_duty = (uint32_t) duty * self->top / ((1 << 16) - 1);
  pwm_set_chan_level(self->slice, self->channel, actual_duty);
 }
 
 uint16_t common_hal_pwmio_pwmout_get_duty_cycle(pwmio_pwmout_obj_t* self) {
  return self->duty_cycle;
 }
 
-void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint32_t top) {
+void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint16_t top) {
  self->actual_frequency = common_hal_mcu_processor_get_frequency() / top;
  self->top = top;
  pwm_set_clkdiv_int_frac(self->slice, 1, 0);
- pwm_set_wrap(self->slice, self->top - 1);
+ pwm_set_wrap(self->slice, self->top);
 }
 
 void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self, uint32_t frequency) {
@@ -187,7 +188,7 @@ void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self, uint32_t fr
  target_slice_frequencies[self->slice] = frequency;
 
  // For low frequencies use the divider to give us full resolution duty_cycle.
- if (frequency < (common_hal_mcu_processor_get_frequency() / (1 << 16))) {
+ if (frequency <= (common_hal_mcu_processor_get_frequency() / (1 << 16))) {
  // Compute the divisor. It's an 8 bit integer and 4 bit fraction. Therefore,
  // we compute everything * 16 for the fractional part.
  // This is 1 << 12 because 4 bits are the * 16.
@@ -202,15 +203,15 @@ void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self, uint32_t fr
  div16 = (1 << 12) - 1;
  }
  self->actual_frequency = frequency16 / div16;
- self->top = 1 << 16;
+ self->top = (1 << 16) - 1;
  pwm_set_clkdiv_int_frac(self->slice, div16 / 16, div16 % 16);
- pwm_set_wrap(self->slice, self->top - 1);
+ pwm_set_wrap(self->slice, self->top);
  } else {
  uint32_t top = common_hal_mcu_processor_get_frequency() / frequency;
  self->actual_frequency = common_hal_mcu_processor_get_frequency() / top;
- self->top = top;
+ self->top = MIN(UINT16_MAX, top - 1);
  pwm_set_clkdiv_int_frac(self->slice, 1, 0);
- pwm_set_wrap(self->slice, self->top - 1);
+ pwm_set_wrap(self->slice, self->top);
  }
  common_hal_pwmio_pwmout_set_duty_cycle(self, self->duty_cycle);
 }

ports/raspberrypi/common-hal/pwmio/PWMOut.h

@@ -39,11 +39,11 @@ typedef struct {
  bool variable_frequency;
  uint16_t duty_cycle;
  uint32_t actual_frequency;
- uint32_t top;
+ uint16_t top;
 } pwmio_pwmout_obj_t;
 
 void pwmout_reset(void);
 // Private API for AudioPWMOut.
-void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint32_t top);
+void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint16_t top);
 
 #endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_PWMIO_PWMOUT_H

shared-bindings/adafruit_bus_device/SPIDevice.c

@@ -34,7 +34,6 @@
 
 #include "lib/utils/buffer_helper.h"
 #include "lib/utils/context_manager_helpers.h"
-#include "py/objproperty.h"
 #include "py/runtime.h"
 #include "supervisor/shared/translate.h"