TTN Smart Sensor (Decentlab)

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 /* https://www.decentlab.com/products/dendrometer-for-lorawan */ var decentlab_decoder = { PROTOCOL_VERSION: 2, SENSORS: [ {length: 4, values: [{name: 'dendrometer_a_position', displayName: 'Dendrometer A Position', convert: function (x) { return ((x[0] + x[1]*65536) / 8388608 - 1) * 20000; }, unit: 'µm'}, {name: 'dendrometer_b_position', displayName: 'Dendrometer B Position', convert: function (x) { return ((x[0] + x[1]*65536) / 8388608 - (x[2] + x[3]*65536) / 8388608) * 20000; }, unit: 'µm'}]}, {length: 1, values: [{name: 'battery_voltage', displayName: 'Battery voltage', convert: function (x) { return x[0] / 1000; }, unit: 'V'}]} ], read_int: function (bytes, pos) { return (bytes[pos] << 8) + bytes[pos + 1]; }, decode: function (msg) { var bytes = msg; var i, j; if (typeof msg === 'string') { bytes = []; for (i = 0; i < msg.length; i += 2) { bytes.push(parseInt(msg.substring(i, i + 2), 16)); } } var version = bytes[0]; if (version != this.PROTOCOL_VERSION) { return {error: "protocol version " + version + " doesn't match v2"}; } var deviceId = this.read_int(bytes, 1); var flags = this.read_int(bytes, 3); var result = {'protocol_version': version, 'device_id': deviceId}; // decode payload var pos = 5; for (i = 0; i < this.SENSORS.length; i++, flags >>= 1) { if ((flags & 1) !== 1) continue; var sensor = this.SENSORS[i]; var x = []; // convert data to 16-bit integer array for (j = 0; j < sensor.length; j++) { x.push(this.read_int(bytes, pos)); pos += 2; } // decode sensor values for (j = 0; j < sensor.values.length; j++) { var value = sensor.values[j]; if ('convert' in value) { result[value.name] = {displayName: value.displayName, value: value.convert.bind(this)(x)}; if ('unit' in value) result[value.name]['unit'] = value.unit; } } } return result; } }; function decodeUplink(input) { var res = decentlab_decoder.decode(input.bytes); if (res.error) { return { errors: [res.error], }; } return { data: res, }; }