ESP32 Forum

Posted: **Wed Aug 28, 2019 6:38 pm**

Hi everyone,

I seem can effortlessly make LEDC high speed timer, but no matter what I try I can't make low speed one start counting.

Here's the task I run from the app_main() function:

Code: Select all

void pwm_task(void *pvParameter) { DPORT_SET_PERI_REG_MASK(DPORT_PERIP_CLK_EN_REG, DPORT_LEDC_CLK_EN); DPORT_CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG, DPORT_LEDC_RST);

  // 0 - 8MHz, 1 - 80 MHz
  WRITE_PERI_REG(LEDC_CONF_REG, 1 << LEDC_APB_CLK_SEL_S);

  // High speed
  WRITE_PERI_REG(LEDC_HSTIMER0_CONF_REG, LEDC_TICK_SEL_HSTIMER0 | (0b000000001001010100 << LEDC_DIV_NUM_HSTIMER0_S) | (4 << LEDC_HSTIMER0_LIM_S));

  // Low speed
  WRITE_PERI_REG(LEDC_LSTIMER1_CONF_REG, (1 << LEDC_TICK_SEL_LSTIMER1_S) | (0b000000001001010100 << LEDC_DIV_NUM_LSTIMER1_S) | (4 << LEDC_LSTIMER1_LIM_S));
  WRITE_PERI_REG(LEDC_LSTIMER1_CONF_REG, LEDC_LSTIMER1_RST | LEDC_LSTIMER1_PARA_UP);

  while(1) {
    vTaskDelay(100 / portTICK_PERIOD_MS);

    uint32_t l = READ_PERI_REG(LEDC_LSTIMER1_VALUE_REG);
    uint32_t h = READ_PERI_REG(LEDC_HSTIMER0_VALUE_REG);
    printf("TIMER low=%d high=%d\n", l, h);
  }
}

I tried:
- configuring SLOW_SPEED with 8MHz and 80MHz
- changing LEDC_DIV_NUM_LSTIMER1 to higher / lower values
- setting LEDC_LSTIMER1_LIM to 15 and 4
- playing with the LEDC_LSTIMER1_PARA_UP and LEDC_LSTIMER1_RST bits
- checking LSTIMER0 and LSTIMER1

After a day on this I'm getting an impression that low speed timers aren't working at all. Can it be the case? Can anyone spot an error in my config?

Thanks!

Posted: **Thu Aug 29, 2019 4:58 am**

I think I tried this example code before and then turned away for some reason -- https://github.com/espressif/esp-idf/bl ... ple_main.c

Now that I tried it again, it worked perfectly for 12 channels that I need to drive servos (8 HS and 4 LS).

Even though not critical now, but if someone could still point out what I was doing wrong with registers, that would be very much appreciated.

ESP32 Forum

Is LEDC low speed timer working?

Is LEDC low speed timer working?

Re: Is LEDC low speed timer working?