src/lib/THERMAL/rpm.cpp

   1 #include "targets.h"
   2
   3 #if defined(PLATFORM_ESP32) && !defined(PLATFORM_ESP32_C3)
   4 #include "logging.h"
   5 #include <driver/pcnt.h>
   6 #include <soc/pcnt_struct.h>
   7
   8 #define TACHO_PULSES_PER_REV 4
   9
  10 static volatile int overflow = 0;
  11 static uint32_t lastTime = 0;
  12
  13 static void IRAM_ATTR pcnt_overflow(void *arg)
  14 {
  15     overflow++;
  16     PCNT.int_clr.val = BIT(PCNT_UNIT_0);
  17     pcnt_counter_clear(PCNT_UNIT_0);
  18 }
  19
  20 void init_rpm_counter(int pin)
  21 {
  22     pcnt_config_t pcnt_config = {};
  23     pcnt_config.pulse_gpio_num = pin;
  24     pcnt_config.ctrl_gpio_num = PCNT_PIN_NOT_USED;
  25     // What to do on the positive / negative edge of pulse input?
  26     pcnt_config.pos_mode = PCNT_COUNT_INC;   // Count up on the positive edge
  27     pcnt_config.neg_mode = PCNT_COUNT_DIS;   // Keep the counter value on the negative edge
  28     // Set the maximum and minimum limit values to watch
  29     pcnt_config.counter_h_lim = 30000;
  30     pcnt_config.counter_l_lim = -1;
  31     pcnt_config.unit = PCNT_UNIT_0;
  32     pcnt_config.channel = PCNT_CHANNEL_0;
  33
  34     /* Initialize PCNT unit */
  35     pcnt_unit_config(&pcnt_config);
  36     /* Configure and enable the input filter */
  37     pcnt_set_filter_value(PCNT_UNIT_0, 100);
  38     pcnt_filter_enable(PCNT_UNIT_0);
  39     /* Enable interrupt on overflow */
  40     pcnt_event_enable(PCNT_UNIT_0, PCNT_EVT_H_LIM);
  41     pcnt_isr_register(pcnt_overflow, NULL, 0, NULL);
  42     pcnt_intr_enable(PCNT_UNIT_0);
  43     /* Initialize PCNT's counter */
  44     pcnt_counter_pause(PCNT_UNIT_0);
  45     pcnt_counter_clear(PCNT_UNIT_0);
  46     /* Everything is set up, now go to counting */
  47     pcnt_counter_resume(PCNT_UNIT_0);
  48 }
  49
  50 uint32_t get_rpm()
  51 {
  52     int16_t counter;
  53     pcnt_get_counter_value(PCNT_UNIT_0, &counter);
  54     pcnt_counter_clear(PCNT_UNIT_0);
  55     uint32_t now = millis();
  56     uint32_t rpm = ((overflow * 30000) + counter) * 60000 / TACHO_PULSES_PER_REV / (now - lastTime);
  57     overflow = 0;
  58     lastTime = now;
  59     return rpm;
  60 }
  61 #endif