mcp9808.cpp

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#include "mcp9808.h"
#include "esphome/core/log.h"
 
namespace esphome::mcp9808 {
 
static const uint8_t MCP9808_REG_AMBIENT_TEMP = 0x05;
static const uint8_t MCP9808_REG_MANUF_ID = 0x06;
static const uint8_t MCP9808_REG_DEVICE_ID = 0x07;
 
static const uint16_t MCP9808_MANUF_ID = 0x0054;
static const uint16_t MCP9808_DEV_ID = 0x0400;
 
static const uint8_t MCP9808_AMBIENT_CLEAR_FLAGS = 0x1F;
static const uint8_t MCP9808_AMBIENT_CLEAR_SIGN = 0x0F;
static const uint8_t MCP9808_AMBIENT_TEMP_NEGATIVE = 0x10;
 
ESPHOME_LOG_TAG(TAG, "mcp9808");
 
void MCP9808Sensor::setup() {
  uint16_t manu = 0;
  if (!this->read_byte_16(MCP9808_REG_MANUF_ID, &manu)) {
    this->mark_failed(LOG_STR(ESP_LOG_MSG_COMM_FAIL));
    return;
  }
  if (manu != MCP9808_MANUF_ID) {
    ESP_LOGE(TAG, "Incorrect manufacturer ID (%X) for '%s'", manu, LOG_STR_ARG(this->get_log_name()));
    this->mark_failed(LOG_STR("Wrong chip ID"));
    return;
  }
  uint16_t dev_id = 0;
  if (!this->read_byte_16(MCP9808_REG_DEVICE_ID, &dev_id)) {
    this->mark_failed(LOG_STR(ESP_LOG_MSG_COMM_FAIL));
    return;
  }
  if (dev_id != MCP9808_DEV_ID) {
    ESP_LOGE(TAG, "Incorrect device ID (%X) for '%s'", dev_id, LOG_STR_ARG(this->get_log_name()));
    this->mark_failed(LOG_STR("Wrong chip ID"));
    return;
  }
}
void MCP9808Sensor::dump_config() {
  ESP_LOGCONFIG(TAG, "%s:", LOG_STR_ARG(this->get_log_name()));
  LOG_I2C_DEVICE(this);
  LOG_UPDATE_INTERVAL(this);
  LOG_SENSOR("  ", "Temperature", this);
}
void MCP9808Sensor::update() {
  uint16_t raw_temp;
  if (!this->read_byte_16(MCP9808_REG_AMBIENT_TEMP, &raw_temp)) {
    this->status_set_warning();
    return;
  }
  if (raw_temp == 0xFFFF) {
    this->status_set_warning();
    return;
  }
 
  float temp = NAN;
  uint8_t msb = (uint8_t) ((raw_temp & 0xff00) >> 8);
  uint8_t lsb = raw_temp & 0x00ff;
 
  msb = msb & MCP9808_AMBIENT_CLEAR_FLAGS;
 
  if ((msb & MCP9808_AMBIENT_TEMP_NEGATIVE) == MCP9808_AMBIENT_TEMP_NEGATIVE) {
    msb = msb & MCP9808_AMBIENT_CLEAR_SIGN;
    temp = (256 - ((uint16_t) (msb) * 16 + lsb / 16.0f)) * -1;
  } else {
    temp = (uint16_t) (msb) * 16 + lsb / 16.0f;
  }
 
  if (!this->status_comm_result(!std::isnan(temp), nullptr))
    return;
 
  ESP_LOGD(TAG, "%s: Got temperature=%.4f°C", LOG_STR_ARG(this->get_log_name()), temp);
  this->publish_state(temp);
}
 
}  // namespace esphome::mcp9808