TTN Smart Sensor (Fludia)

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const PAYLOAD_TYPE = { T1 : {header: 0x57, size: 42/*in bytes*/, name: "T1"}, T2 : {header: 0x58, size: 12/*in bytes*/, name: "T2"}, START : {header: 0x01, size: 3/*in bytes*/, name: "START"} } //Main function Decoder function decodeUplink(input){ var decoded = { data: { index : null, message_type : null, temperatures : [], time_step: null, meter_type : "Temperature", firmware_version: null, max_temp: null, min_temp: null, max_temp_variation: null, sampling : null, temperature: null }, warnings: [], errors: [] } //Find message type decoded.data.message_type = find_message_type(input.bytes); if(decoded.data.message_type == null){ decoded.errors.push("Invalid payload") return decoded } //Decode message if(decoded.data.message_type == PAYLOAD_TYPE.T1.name){ var data = decode_T1(input.bytes); decoded.data.index = data.index; decoded.data.temperatures = data.temperatures; decoded.data.time_step = data.time_step; }else if(decoded.data.message_type == PAYLOAD_TYPE.T2.name){ var data = decode_T2(input.bytes); decoded.data.firmware_version = data.firmware_version; decoded.data.time_step = data.time_step; decoded.data.max_temp = data.max_temp; decoded.data.max_temp_variation = data.max_temp_variation; decoded.data.min_temp = data.min_temp; decoded.data.sampling = data.sampling; } //Retrocompatibility decoded.data.temperature = decoded.data.temperatures; return decoded } //Find message type - return null if nothing found function find_message_type(payload){ switch(payload[0]){ case PAYLOAD_TYPE.T1.header: if(payload.length == PAYLOAD_TYPE.T1.size) return PAYLOAD_TYPE.T1.name break; case PAYLOAD_TYPE.T2.header: if(payload.length == PAYLOAD_TYPE.T2.size) return PAYLOAD_TYPE.T2.name break; case PAYLOAD_TYPE.START.header: if(payload.length == PAYLOAD_TYPE.START.size) return PAYLOAD_TYPE.START.name break; } return null } function decode_T1(payload){ var data = {}; data.time_step = payload[1]; data.temperatures = [] for(i=0;i<20;i++){ data.temperatures.push(toSignedInt16(payload[2+2*i], payload[3+2*i])/100) } return data } function decode_T2(payload){ var data = {}; data.firmware_version = String.fromCharCode(payload[1])+"."+String.fromCharCode(payload[2])+"."+String.fromCharCode(payload[3]); data.time_step = payload[4]; data.max_temp = toSignedInt16(payload[5], payload[6])/100; data.min_temp = toSignedInt16(payload[7], payload[8])/100; data.max_temp_variation = toSignedInt16(payload[9], payload[10])/100; data.sampling = payload[11]; if(data.sampling == 0) data.sampling = "average"; if(data.sampling == 1) data.sampling = "instantaneous" return data; } function toSignedInt16(byte1, byte2){ if(byte1 & 0x80) return ((byte1 & 0x7F) - 0x80) << 8 | byte2; else return (byte1 & 0x7F) << 8 | byte2; }