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esp32: Always set the duty cycle when setting the frequency. #8361

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esp32: Always set the duty cycle when setting the frequency. #8361

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7d0bb77
esp32: Always set the duty cycle when setting the frequency.
robert-hh Feb 27, 2022
1622b26
esp32: Implement review comments.
robert-hh Mar 1, 2022
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59 changes: 35 additions & 24 deletions ports/esp32/machine_pwm.c
100755 → 100644
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Original file line number Diff line number Diff line change
Expand Up @@ -74,7 +74,8 @@ STATIC ledc_timer_config_t timers[PWM_TIMER_MAX];
// Params for PWM operation
// 5khz is default frequency
#define PWM_FREQ (5000)
// default 10-bit resolution (compatible with esp8266 PWM)

// 10-bit resolution (compatible with esp8266 PWM)
#define PWM_RES_10_BIT (LEDC_TIMER_10_BIT)

// Maximum duty value on 10-bit resolution
Expand All @@ -84,15 +85,17 @@ STATIC ledc_timer_config_t timers[PWM_TIMER_MAX];
// duty_u16() and duty_ns() use 16-bit resolution or less

// Possible highest resolution in device
#if CONFIG_IDF_TARGET_ESP32
#define HIGHEST_PWM_RES (LEDC_TIMER_16_BIT) // 20 bit for ESP32, but 16 bit is used
#if (LEDC_TIMER_BIT_MAX - 1) < LEDC_TIMER_16_BIT
#define HIGHEST_PWM_RES (LEDC_TIMER_BIT_MAX - 1)
#else
#define HIGHEST_PWM_RES (LEDC_TIMER_BIT_MAX - 1) // 14 bit is used
#define HIGHEST_PWM_RES (LEDC_TIMER_16_BIT) // 20 bit for ESP32, but 16 bit is used
#endif
// Duty resolution of user interface in `duty_u16()` and `duty_u16` parameter in constructor/initializer
#define UI_RES_16_BIT (16)
// Maximum duty value on highest user interface resolution
#define UI_MAX_DUTY ((1 << UI_RES_16_BIT) - 1)
// How much to shift from the HIGHEST_PWM_RES duty resolution to the user interface duty resolution UI_RES_16_BIT
#define UI_RES_SHIFT (UI_RES_16_BIT - HIGHEST_PWM_RES) // 0 for ESP32, 2 for S2, S3, C3

// If the PWM frequency is less than EMPIRIC_FREQ, then LEDC_REF_CLK_HZ(1 MHz) source is used, else LEDC_APB_CLK_HZ(80 MHz) source is used
#define EMPIRIC_FREQ (10) // Hz
Expand All @@ -108,7 +111,7 @@ typedef struct _machine_pwm_obj_t {
int mode;
int channel;
int timer;
int duty_x; // PWM_RES_10_BIT if duty(), UI_RES_16_BIT if duty_u16(), -UI_RES_16_BIT if duty_ns()
int duty_x; // PWM_RES_10_BIT if duty(), HIGHEST_PWM_RES if duty_u16(), -HIGHEST_PWM_RES if duty_ns()
int duty_u10; // stored values from previous duty setters
int duty_u16; // - / -
int duty_ns; // - / -
Expand Down Expand Up @@ -208,7 +211,6 @@ STATIC void set_freq(machine_pwm_obj_t *self, unsigned int freq, ledc_timer_conf
if (freq < EMPIRIC_FREQ) {
i = LEDC_REF_CLK_HZ; // 1 MHz
}

#if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(5, 0, 0)
// original code
i /= freq;
Expand Down Expand Up @@ -237,7 +239,6 @@ STATIC void set_freq(machine_pwm_obj_t *self, unsigned int freq, ledc_timer_conf
}

// Configure the new resolution and frequency
unsigned int save_duty_resolution = timer->duty_resolution;
timer->duty_resolution = res;
timer->freq_hz = freq;
timer->clk_cfg = LEDC_USE_APB_CLK;
Expand All @@ -258,17 +259,15 @@ STATIC void set_freq(machine_pwm_obj_t *self, unsigned int freq, ledc_timer_conf
if (self->mode == LEDC_LOW_SPEED_MODE) {
check_esp_err(ledc_timer_rst(self->mode, self->timer));
}
}

// Save the same duty cycle when frequency is changed
if (save_duty_resolution != timer->duty_resolution) {
if (self->duty_x == UI_RES_16_BIT) {
set_duty_u16(self, self->duty_u16);
} else if (self->duty_x == PWM_RES_10_BIT) {
set_duty_u10(self, self->duty_u10);
} else if (self->duty_x == -UI_RES_16_BIT) {
set_duty_ns(self, self->duty_ns);
}
}
// Save the same duty cycle when frequency is changed
if (self->duty_x == HIGHEST_PWM_RES) {
set_duty_u16(self, self->duty_u16);
} else if (self->duty_x == PWM_RES_10_BIT) {
set_duty_u10(self, self->duty_u10);
} else if (self->duty_x == -HIGHEST_PWM_RES) {
set_duty_ns(self, self->duty_ns);
}
}

Expand All @@ -293,11 +292,18 @@ STATIC int duty_to_ns(machine_pwm_obj_t *self, int duty) {
#define get_duty_raw(self) ledc_get_duty(self->mode, self->channel)

STATIC uint32_t get_duty_u16(machine_pwm_obj_t *self) {
return ledc_get_duty(self->mode, self->channel) << (UI_RES_16_BIT - timers[TIMER_IDX(self->mode, self->timer)].duty_resolution);
int resolution = timers[TIMER_IDX(self->mode, self->timer)].duty_resolution;
int duty = ledc_get_duty(self->mode, self->channel);
if (resolution <= UI_RES_16_BIT) {
duty <<= (UI_RES_16_BIT - resolution);
} else {
duty >>= (resolution - UI_RES_16_BIT);
}
return duty;
}

STATIC uint32_t get_duty_u10(machine_pwm_obj_t *self) {
return get_duty_u16(self) >> (UI_RES_16_BIT - LEDC_TIMER_10_BIT);
return get_duty_u16(self) >> 6; // Scale down from 16 bit to 10 bit resolution
}

STATIC uint32_t get_duty_ns(machine_pwm_obj_t *self) {
Expand All @@ -309,7 +315,12 @@ STATIC void set_duty_u16(machine_pwm_obj_t *self, int duty) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("duty_u16 must be from 0 to %d"), UI_MAX_DUTY);
}
ledc_timer_config_t timer = timers[TIMER_IDX(self->mode, self->timer)];
int channel_duty = duty >> (UI_RES_16_BIT - timer.duty_resolution);
int channel_duty;
if (timer.duty_resolution <= UI_RES_16_BIT) {
channel_duty = duty >> (UI_RES_16_BIT - timer.duty_resolution);
} else {
channel_duty = duty << (timer.duty_resolution - UI_RES_16_BIT);
}
int max_duty = (1 << timer.duty_resolution) - 1;
if (channel_duty < 0) {
channel_duty = 0;
Expand All @@ -333,15 +344,15 @@ STATIC void set_duty_u16(machine_pwm_obj_t *self, int duty) {
}
*/

self->duty_x = UI_RES_16_BIT;
self->duty_x = HIGHEST_PWM_RES;
self->duty_u16 = duty;
}

STATIC void set_duty_u10(machine_pwm_obj_t *self, int duty) {
if ((duty < 0) || (duty > MAX_DUTY_U10)) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("duty must be from 0 to %u"), MAX_DUTY_U10);
}
set_duty_u16(self, duty << (UI_RES_16_BIT - LEDC_TIMER_10_BIT));
set_duty_u16(self, duty << (UI_RES_16_BIT - PWM_RES_10_BIT));
self->duty_x = PWM_RES_10_BIT;
self->duty_u10 = duty;
}
Expand All @@ -351,7 +362,7 @@ STATIC void set_duty_ns(machine_pwm_obj_t *self, int ns) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("duty_ns must be from 0 to %d ns"), duty_to_ns(self, UI_MAX_DUTY));
}
set_duty_u16(self, ns_to_duty(self, ns));
self->duty_x = -UI_RES_16_BIT;
self->duty_x = -HIGHEST_PWM_RES;
self->duty_ns = ns;
}

Expand Down Expand Up @@ -424,7 +435,7 @@ STATIC void mp_machine_pwm_print(const mp_print_t *print, mp_obj_t self_in, mp_p

if (self->duty_x == PWM_RES_10_BIT) {
mp_printf(print, ", duty=%d", get_duty_u10(self));
} else if (self->duty_x == -UI_RES_16_BIT) {
} else if (self->duty_x == -HIGHEST_PWM_RES) {
mp_printf(print, ", duty_ns=%d", get_duty_ns(self));
} else {
mp_printf(print, ", duty_u16=%d", get_duty_u16(self));
Expand Down
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