8000 esp32/pwm: Use IDF functions to calculate resolution correctly. by andrewleech · Pull Request #16090 · micropython/micropython · GitHub
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esp32/pwm: Use IDF functions to calculate resolution correctly. #16090

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Merged
merged 1 commit into from
Oct 30, 2024
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esp32/pwm: Use IDF functions to calculate resolution correctly. #16090

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50 changes: 16 additions & 34 deletions ports/esp32/machine_pwm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@
#include "py/mphal.h"
#include "driver/ledc.h"
#include "esp_err.h"
#include "esp_clk_tree.h"
#include "soc/gpio_sig_map.h"

#define PWM_DBG(...)
Expand Down Expand Up @@ -209,51 +210,32 @@ static void configure_channel(machine_pwm_obj_t *self) {

static void set_freq(machine_pwm_obj_t *self, unsigned int freq, ledc_timer_config_t *timer) {
if (freq != timer->freq_hz) {
// Find the highest bit resolution for the requested frequency
unsigned int i = APB_CLK_FREQ; // 80 MHz
#if SOC_LEDC_SUPPORT_REF_TICK
if (freq < EMPIRIC_FREQ) {
i = REF_CLK_FREQ; // 1 MHz
}
#endif

int divider = (i + freq / 2) / freq; // rounded
if (divider == 0) {
divider = 1;
}
float f = (float)i / divider; // actual frequency
if (f <= 1.0) {
f = 1.0;
}
i = (unsigned int)roundf((float)i / f);

unsigned int res = 0;
for (; i > 1; i >>= 1) {
++res;
}
if (res == 0) {
res = 1;
} else if (res > HIGHEST_PWM_RES) {
// Limit resolution to HIGHEST_PWM_RES to match units of our duty
res = HIGHEST_PWM_RES;
}

// Configure the new resolution and frequency
timer->duty_resolution = res;
// Configure the new frequency and resolution
timer->freq_hz = freq;
#if SOC_LEDC_SUPPORT_XTAL_CLOCK

#if SOC_LEDC_SUPPORT_PLL_DIV_CLOCK
timer->clk_cfg = LEDC_USE_PLL_DIV_CLK;
#elif SOC_LEDC_SUPPORT_APB_CLOCK
timer->clk_cfg = LEDC_USE_APB_CLK;
#elif SOC_LEDC_SUPPORT_XTAL_CLOCK
timer->clk_cfg = LEDC_USE_XTAL_CLK;
#else
timer->clk_cfg = LEDC_USE_APB_CLK;
#error No supported PWM / LEDC clocks.
#endif
#if SOC_LEDC_SUPPORT_REF_TICK
if (freq < EMPIRIC_FREQ) {
timer->clk_cfg = LEDC_USE_REF_TICK;
}
#endif
uint32_t src_clk_freq = 0;
esp_err_t err = esp_clk_tree_src_get_freq_hz(timer->clk_cfg, ESP_CLK_TREE_SRC_FREQ_PRECISION_CACHED, &src_clk_freq);
if (err != ESP_OK) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("unable to query source clock frequency %d"), (int)timer->clk_cfg);
}
timer->duty_resolution = ledc_find_suitable_duty_resolution(src_clk_freq, timer->freq_hz);

// Set frequency
esp_err_t err = ledc_timer_config(timer);
err = ledc_timer_config(timer);
if (err != ESP_OK) {
if (err == ESP_FAIL) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("unreachable frequency %d"), freq);
Expand Down
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