uint8_t Adafruit_Fingerprint::downloadModel(uint16_t id, uint8_t packet_1[], uint8_t packet_2[], uint8_t slot) {
  uint8_t packet[] = {FINGERPRINT_DOWNLOAD, slot};
  writePacket(theAddress, FINGERPRINT_COMMANDPACKET, sizeof(packet)+2, packet);
  uint8_t len = getReply(recvPacket);

  if ((len != 1) && (recvPacket[0] != FINGERPRINT_ACKPACKET))
   return -1;
  if (recvPacket[1] == 0x00) {
    writePacket(theAddress, FINGERPRINT_DATAPACKET, sizeof(packet_1)+2, packet_1);
    writePacket(theAddress, FINGERPRINT_DATAPACKET, sizeof(packet_2)+2, packet_2);
    return recvPacket[1];
  } else {
    return recvPacket[1];
  }
}