@signalk/nmea0183-signalk/hooks/MTA.js

A node.js/javascript parser for NMEA0183 sentences. Sentences are parsed to Signal K format.

/**
 * Copyright 2016 Signal K <info@signalk.org> and contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

'use strict'

const utils = require('@signalk/nmea0183-utilities')

/*
 * MTA - Mean Temperature of Air
 *
 *        0   1 2
 *        |   | |
 * $--MTA,x.x,C*hh<CR><LF>
 *
 * Field Number:
 *   0.    Degrees
 *   1.    Unit of Measurement, Celsius
 *   2.    Checksum
 *
 */

module.exports = function (input) {
  const { id, sentence, parts, tags } = input

  if (parts[1] != 'C') {
    return null
  }
  const delta = {
    updates: [
      {
        source: tags.source,
        timestamp: tags.timestamp,
        values: [
          {
            path: 'environment.outside.temperature',
            value: parts.length > 0 && parts[0].trim().length > 0 ? utils.transform(utils.float(parts[0]), 'c', 'k') : null,
          },
        ],
      },
    ],
  }

  return delta
}