code: function encode(rssi) {
    if(rssi < MIN_RSSI_DBM) {
      rssi = MIN_RSSI_DBM;
    }
    else if(rssi > MAX_RSSI_DBM) {
      rssi = MAX_RSSI_DBM;
    }
    else {
      rssi = Math.round(rssi);
    }
  
    return ('00' + (rssi - MIN_RSSI_DBM).toString(16)).substr(-2);
  }
docs: Encode the given RSSI value as a hexadecimal string byte.
  @param {Number} rssi The given RSSI in dBm.
  @return {String} The resulting hexadecimal string.