esphome/esphome/components/shtcx/shtcx.cpp

#include "shtcx.h"
#include "esphome/core/log.h"
#include "esphome/core/hal.h"

namespace esphome {
namespace shtcx {

static const char *const TAG = "shtcx";

static const uint16_t SHTCX_COMMAND_SLEEP = 0xB098;
static const uint16_t SHTCX_COMMAND_WAKEUP = 0x3517;
static const uint16_t SHTCX_COMMAND_READ_ID_REGISTER = 0xEFC8;
static const uint16_t SHTCX_COMMAND_SOFT_RESET = 0x805D;
static const uint16_t SHTCX_COMMAND_POLLING_H = 0x7866;

inline const char *to_string(SHTCXType type) {
  switch (type) {
    case SHTCX_TYPE_SHTC3:
      return "SHTC3";
    case SHTCX_TYPE_SHTC1:
      return "SHTC1";
    default:
      return "[Unknown model]";
  }
}

void SHTCXComponent::setup() {
  ESP_LOGCONFIG(TAG, "Setting up SHTCx...");
  this->wake_up();
  this->soft_reset();

  if (!this->write_command_(SHTCX_COMMAND_READ_ID_REGISTER)) {
    ESP_LOGE(TAG, "Error requesting Device ID");
    this->mark_failed();
    return;
  }

  uint16_t device_id_register[1];
  if (!this->read_data_(device_id_register, 1)) {
    ESP_LOGE(TAG, "Error reading Device ID");
    this->mark_failed();
    return;
  }

  if (((device_id_register[0] << 2) & 0x1C) == 0x1C) {
    if ((device_id_register[0] & 0x847) == 0x847) {
      this->type_ = SHTCX_TYPE_SHTC3;
    } else {
      this->type_ = SHTCX_TYPE_SHTC1;
    }
  } else {
    this->type_ = SHTCX_TYPE_UNKNOWN;
  }
  ESP_LOGCONFIG(TAG, "  Device identified: %s", to_string(this->type_));
}
void SHTCXComponent::dump_config() {
  ESP_LOGCONFIG(TAG, "SHTCx:");
  ESP_LOGCONFIG(TAG, "  Model: %s", to_string(this->type_));
  LOG_I2C_DEVICE(this);
  if (this->is_failed()) {
    ESP_LOGE(TAG, "Communication with SHTCx failed!");
  }
  LOG_UPDATE_INTERVAL(this);

  LOG_SENSOR("  ", "Temperature", this->temperature_sensor_);
  LOG_SENSOR("  ", "Humidity", this->humidity_sensor_);
}
float SHTCXComponent::get_setup_priority() const { return setup_priority::DATA; }
void SHTCXComponent::update() {
  if (this->status_has_warning()) {
    ESP_LOGW(TAG, "Retrying to reconnect the sensor.");
    this->soft_reset();
  }
  if (this->type_ != SHTCX_TYPE_SHTC1) {
    this->wake_up();
  }
  if (!this->write_command_(SHTCX_COMMAND_POLLING_H)) {
    this->status_set_warning();
    return;
  }

  this->set_timeout(50, [this]() {
    uint16_t raw_data[2];
    if (!this->read_data_(raw_data, 2)) {
      this->status_set_warning();
      return;
    }

    float temperature = 175.0f * float(raw_data[0]) / 65536.0f - 45.0f;
    float humidity = 100.0f * float(raw_data[1]) / 65536.0f;

    ESP_LOGD(TAG, "Got temperature=%.2f°C humidity=%.2f%%", temperature, humidity);
    if (this->temperature_sensor_ != nullptr)
      this->temperature_sensor_->publish_state(temperature);
    if (this->humidity_sensor_ != nullptr)
      this->humidity_sensor_->publish_state(humidity);
    this->status_clear_warning();
    if (this->type_ != SHTCX_TYPE_SHTC1) {
      this->sleep();
    }
  });
}

bool SHTCXComponent::write_command_(uint16_t command) {
  // Warning ugly, trick the I2Ccomponent base by setting register to the first 8 bit.
  return this->write_byte(command >> 8, command & 0xFF);
}

uint8_t sht_crc(uint8_t data1, uint8_t data2) {
  uint8_t bit;
  uint8_t crc = 0xFF;

  crc ^= data1;
  for (bit = 8; bit > 0; --bit) {
    if (crc & 0x80)
      crc = (crc << 1) ^ 0x131;
    else
      crc = (crc << 1);
  }

  crc ^= data2;
  for (bit = 8; bit > 0; --bit) {
    if (crc & 0x80)
      crc = (crc << 1) ^ 0x131;
    else
      crc = (crc << 1);
  }

  return crc;
}

bool SHTCXComponent::read_data_(uint16_t *data, uint8_t len) {
  const uint8_t num_bytes = len * 3;
  std::vector<uint8_t> buf(num_bytes);

  if (this->read(buf.data(), num_bytes) != i2c::ERROR_OK) {
    return false;
  }

  for (uint8_t i = 0; i < len; i++) {
    const uint8_t j = 3 * i;
    uint8_t crc = sht_crc(buf[j], buf[j + 1]);
    if (crc != buf[j + 2]) {
      ESP_LOGE(TAG, "CRC8 Checksum invalid! 0x%02X != 0x%02X", buf[j + 2], crc);
      return false;
    }
    data[i] = (buf[j] << 8) | buf[j + 1];
  }

  return true;
}

void SHTCXComponent::soft_reset() {
  this->write_command_(SHTCX_COMMAND_SOFT_RESET);
  delayMicroseconds(200);
}
void SHTCXComponent::sleep() { this->write_command_(SHTCX_COMMAND_SLEEP); }

void SHTCXComponent::wake_up() {
  this->write_command_(SHTCX_COMMAND_WAKEUP);
  delayMicroseconds(200);
}

}  // namespace shtcx
}  // namespace esphome