@growbox/sensors/src/sensors/Ds18b20Sensor.js

An abstraction layer for a selection of raspberry-compatible sensors

/**
 * @author nstCactus
 * @date 06/12/2017 13:13
 */

//@formatter:off
const ds18b20            = require('ds18b20-raspi');
const AbstractSensor     = require('./AbstractSensor');
const SensorValue        = require('../SensorValue');
const SensorError        = require('../errors/SensorError');
//@formatter:on

/**
 * A ds18b20 temperature sensor
 */
class Ds18b20Sensor extends AbstractSensor {
  /**
   * Read from the sensor to get the current temperature
   * @returns {Promise<SensorValue[]>} A promise that, when fulfilled, contains an array which consists of a single
   *                                   SensorValue: the current temperature
   */
  async read() {
    const ds18b20Sensors = ds18b20.list();

    return new Promise((resolve, reject) => {
      if (ds18b20Sensors.indexOf(this.uid) >= 0) {
        const value = ds18b20.readC(this.uid, 2);

        resolve([new SensorValue(SensorValue.TypeEnum.TEMPERATURE, value)]);
      } else {
        reject(new ReferenceError(`Skipping ds18b20 sensor "${this.name}" as no sensor with this id was found`));
      }
    });
  }

  /**
   * @returns {Promise<string[]>} A Promise that, when fulfilled, contains an array of the ids of all ds18b20 sensors
   * connected to the 1-wire bus.
   */
  static async list() {
    return new Promise((resolve, reject) => {
      ds18b20.list((err, deviceIds) => {
        if (err) {
          // No, no sensor found isn't an error!
          if (err.indexOf('any 1-Wire sensors to list') > -1) {
            resolve([]);
          } else {
            reject (new SensorError(err));
          }
        } else {
          resolve(deviceIds);
        }
      });
    });
  }
}


module.exports = Ds18b20Sensor;