digital_pcnt_input.cpp

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#include "digital_pcnt_input.h"
 
#include "esp_log.h"
 
#if ESP_ARDUINO_VERSION_MAJOR < 3
#warning "The Pulse Counter API is only available in ESP32 Arduino Core 3.0.0 and later"
#else
#include "driver/pulse_cnt.h"
 
namespace sensesp {
 
DigitalInputPcntCounter::DigitalInputPcntCounter(uint8_t pin, int pin_mode,
                                                 int interrupt_type,
                                                 unsigned int read_delay,
                                                 String config_path)
    : DigitalInput(pin, pin_mode),
      Sensor(config_path),
      read_delay_(read_delay),
      interrupt_type_(interrupt_type) {
  load();
 
  ESP_ERROR_CHECK(configurePcnt(interrupt_type));
 
  event_loop()->onRepeat(read_delay_, [this]() {
    // Note: there is a small TOCTOU window between pcnt_unit_get_count and
    // pcnt_unit_clear_count where pulses can be lost. noInterrupts() does not
    // help because PCNT is a hardware counter that counts independently.
    int count = 0;
    ESP_ERROR_CHECK(pcnt_unit_get_count(pcnt_unit_, &count));
    ESP_ERROR_CHECK(pcnt_unit_clear_count(pcnt_unit_));
    output_ = count;
    notify();
  });
}
 
DigitalInputPcntCounter::~DigitalInputPcntCounter() {
  esp_err_t err;
  if (pcnt_channel_) {
    err = pcnt_del_channel(pcnt_channel_);
    if (err != ESP_OK) {
      ESP_LOGE("PCNT", "Failed to delete PCNT channel: %s", esp_err_to_name(err));
    }
  }
  if (pcnt_unit_) {
    err = pcnt_unit_stop(pcnt_unit_);
    if (err != ESP_OK) {
      ESP_LOGE("PCNT", "Failed to stop PCNT unit: %s", esp_err_to_name(err));
    }
    err = pcnt_unit_disable(pcnt_unit_);
    if (err != ESP_OK) {
      ESP_LOGE("PCNT", "Failed to disable PCNT unit: %s", esp_err_to_name(err));
    }
    err = pcnt_del_unit(pcnt_unit_);
    if (err != ESP_OK) {
      ESP_LOGE("PCNT", "Failed to delete PCNT unit: %s", esp_err_to_name(err));
    }
  }
}
 
esp_err_t DigitalInputPcntCounter::configurePcnt(int interrupt_mode) {
  pcnt_unit_config_t unit_config = {
      .low_limit = -1,
      .high_limit = INT16_MAX,
  };
 
  ESP_ERROR_CHECK(pcnt_new_unit(&unit_config, &pcnt_unit_));
 
  pcnt_chan_config_t chan_config = {.edge_gpio_num = pin_,
                                    .level_gpio_num = -1,
                                    .flags = {.invert_edge_input = false,
                                              .invert_level_input = false,
                                              .virt_edge_io_level = 0,
                                              .virt_level_io_level = 0,
                                              .io_loop_back = false}};
 
  ESP_ERROR_CHECK(pcnt_new_channel(pcnt_unit_, &chan_config, &pcnt_channel_));
 
  pcnt_channel_edge_action_t edge_action_pos =
      (interrupt_mode == RISING || interrupt_mode == CHANGE)
          ? PCNT_CHANNEL_EDGE_ACTION_INCREASE
          : PCNT_CHANNEL_EDGE_ACTION_HOLD;
  pcnt_channel_edge_action_t edge_action_neg =
      (interrupt_mode == FALLING || interrupt_mode == CHANGE)
          ? PCNT_CHANNEL_EDGE_ACTION_INCREASE
          : PCNT_CHANNEL_EDGE_ACTION_HOLD;
  ESP_ERROR_CHECK(pcnt_channel_set_edge_action(pcnt_channel_, edge_action_pos,
                                               edge_action_neg));
 
  ESP_ERROR_CHECK(pcnt_unit_enable(pcnt_unit_));
  ESP_ERROR_CHECK(pcnt_unit_clear_count(pcnt_unit_));
 
  return pcnt_unit_start(pcnt_unit_);
}
 
bool DigitalInputPcntCounter::to_json(JsonObject& root) {
  root["read_delay"] = read_delay_;
  return true;
}
 
bool DigitalInputPcntCounter::from_json(const JsonObject& config) {
  String const expected[] = {"read_delay"};
  for (auto str : expected) {
    if (!config[str].is<JsonVariant>()) {
      return false;
    }
  }
  read_delay_ = config["read_delay"];
  return true;
}
 
const String ConfigSchema(const DigitalInputPcntCounter& obj) {
  return R"###({"type":"object","properties":{"read_delay":{"title":"Read delay","type":"number","description":"The time, in milliseconds, between each read of the input"}}  })###";
}
 
bool ConfigRequiresRestart(const DigitalInputPcntCounter& obj) { return true; }
 
}  // namespace sensesp
 
#endif  // ESP_ARDUINO_VERSION_MAJOR < 3