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Revise PWM period generation algorithm to match other ports

This commit is contained in:
Hierophect 2019-10-31 16:59:44 -04:00
parent bb8046dbb3
commit 0a1a12b867
2 changed files with 38 additions and 12 deletions
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49
ports/stm32f4/common-hal/pulseio/PWMOut.c
View File

@ -35,7 +35,6 @@
#include "stm32f4xx_hal.h"
#include "common-hal/microcontroller/Pin.h"
#define PULSE_RESOLUTION 256 //8 bit
#define ALL_CLOCKS 0xFFFF
STATIC uint8_t reserved_tim[TIM_BANK_ARRAY_LEN];
@ -183,12 +182,21 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
}
uint32_t source_freq = timer_get_source_freq(self->tim->tim_index);
if (frequency == 0 || frequency * PULSE_RESOLUTION > (source_freq)) {
uint32_t prescaler = 0;
uint32_t period = 0;
for (int i=0; i<32767;i++) {
period = source_freq/(i*frequency);
if (period <= 65535 && period>=2) {
prescaler = i;
break;
}
}
if (prescaler == 0) {
mp_raise_ValueError(translate("Invalid frequency supplied"));
}
uint32_t prescaler = source_freq/(frequency*PULSE_RESOLUTION);
uint32_t period = PULSE_RESOLUTION;
uint32_t input = (duty*PULSE_RESOLUTION)/65535;
uint32_t input = (duty*period)/65535;
//Used for Debugging
// mp_printf(&mp_plat_print, "Duty:%d, Pulses:%d\n", duty,input);
// mp_printf(&mp_plat_print, "SysCoreClock: %d\n", SystemCoreClock);
@ -231,6 +239,7 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
self->variable_frequency = variable_frequency;
self->frequency = frequency;
self->duty_cycle = duty;
self->period = period;
return PWMOUT_OK;
}
@ -261,7 +270,7 @@ void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
}
void common_hal_pulseio_pwmout_set_duty_cycle(pulseio_pwmout_obj_t* self, uint16_t duty_cycle) {
uint32_t input = (duty_cycle*PULSE_RESOLUTION)/65535;
uint32_t input = (duty_cycle*self->period)/65535;
//Used for debugging
//mp_printf(&mp_plat_print, "duty_cycle %d, Duty: %d, Input %d\n", duty_cycle, duty, input);
__HAL_TIM_SET_COMPARE(&self->handle, self->channel, input);
@ -277,15 +286,30 @@ void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, uint32_
//don't halt setup for the same frequency
if (frequency == self->frequency) return;
//calculate new values
uint32_t source_freq = timer_get_source_freq(self->tim->tim_index);
if (frequency == 0 || frequency*PULSE_RESOLUTION > (source_freq)) {
uint32_t prescaler = 0;
uint32_t period = 0;
for (int i=0; i<32767;i++) {
period = source_freq/(i*frequency);
if (period <= 65535 && period>=2) {
prescaler = i;
break;
}
}
if (prescaler == 0) {
mp_raise_ValueError(translate("Invalid frequency supplied"));
}
uint32_t prescaler = source_freq/(frequency*PULSE_RESOLUTION);
uint32_t period = PULSE_RESOLUTION;
//this shouldn't ever exceed 0xffff*0xffff = 0xfffe0001, so it won't integer overflow.
uint32_t input = (self->duty_cycle*PULSE_RESOLUTION)/65535;
uint32_t input = (self->duty_cycle*period)/65535;
//debugging output
// mp_printf(&mp_plat_print, "Duty:%d, Pulses:%d\n", self->duty_cycle,input);
// mp_printf(&mp_plat_print, "Period: %d\n", period);
// mp_printf(&mp_plat_print, "Source Freq: %d\n", source_freq);
// mp_printf(&mp_plat_print, "Prescaler %d, Timer Freq: %d\n", prescaler, source_freq/prescaler);
// mp_printf(&mp_plat_print, "Output Freq: %d\n", (source_freq/prescaler)/period);
// mp_printf(&mp_plat_print, "TIM#:%d CH:%d ALTF:%d\n", self->tim->tim_index, self->tim->channel_index, self->tim->altfn_index);
//shut down
HAL_TIM_PWM_Stop(&self->handle, self->channel);
@ -310,6 +334,7 @@ void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, uint32_
tim_frequencies[self->tim->tim_index-1] = frequency;
self->frequency = frequency;
self->period = period;
}
uint32_t common_hal_pulseio_pwmout_get_frequency(pulseio_pwmout_obj_t* self) {

1
ports/stm32f4/common-hal/pulseio/PWMOut.h
View File

@ -43,6 +43,7 @@ typedef struct {
bool variable_frequency: 1;
uint16_t duty_cycle;
uint32_t frequency;
uint32_t period;
} pulseio_pwmout_obj_t;
void pwmout_reset(void);