def send_data(self, data, data_length, frame_counter, timeout=5):
# Data packet
enc_data = bytearray(data_length)
lora_pkt = bytearray(64)
# Copy bytearray into bytearray for encryption
enc_data[0:data_length] = data[0:data_length]
# Encrypt data (enc_data is overwritten in this function)
self.frame_counter = frame_counter
aes = AES(self._ttn_config.device_address, self._ttn_config.app_key,
self._ttn_config.network_key, self.frame_counter)
enc_data = aes.encrypt(enc_data)
# Construct MAC Layer packet (PHYPayload)
# MHDR (MAC Header) - 1 byte
lora_pkt[
0] = REG_DIO_MAPPING_1 # MType: unconfirmed data up, RFU / Major zeroed
# MACPayload
# FHDR (Frame Header): DevAddr (4 bytes) - short device address
lora_pkt[1] = self._ttn_config.device_address[3]
lora_pkt[2] = self._ttn_config.device_address[2]
lora_pkt[3] = self._ttn_config.device_address[1]
lora_pkt[4] = self._ttn_config.device_address[0]
# FHDR (Frame Header): FCtrl (1 byte) - frame control
lora_pkt[5] = 0x00
# FHDR (Frame Header): FCnt (2 bytes) - frame counter
lora_pkt[6] = self.frame_counter & 0x00FF
lora_pkt[7] = (self.frame_counter >> 8) & 0x00FF
# FPort - port field
lora_pkt[8] = self._fport
# Set length of LoRa packet
lora_pkt_len = 9
if __DEBUG__:
print("PHYPayload", ubinascii.hexlify(lora_pkt))
# load encrypted data into lora_pkt
lora_pkt[lora_pkt_len:lora_pkt_len +
data_length] = enc_data[0:data_length]
if __DEBUG__:
print("PHYPayload with FRMPayload", ubinascii.hexlify(lora_pkt))
# Recalculate packet length
lora_pkt_len += data_length
# Calculate Message Integrity Code (MIC)
# MIC is calculated over: MHDR | FHDR | FPort | FRMPayload
mic = bytearray(4)
mic = aes.calculate_mic(lora_pkt, lora_pkt_len, mic)
# Load MIC in package
lora_pkt[lora_pkt_len:lora_pkt_len + 4] = mic[0:4]
# Recalculate packet length (add MIC length)
lora_pkt_len += 4
if __DEBUG__:
print("PHYPayload with FRMPayload + MIC",
ubinascii.hexlify(lora_pkt))
self.send_packet(lora_pkt, lora_pkt_len, timeout)
def handle_on_receive(self, event_source):
self.set_lock(True) # lock until TX_Done
aes = AES(self._ttn_config.device_address, self._ttn_config.app_key,
self._ttn_config.network_key, self.frame_counter)
# irqFlags = self.getIrqFlags() should be 0x50
if (self.get_irq_flags() & IRQ_PAYLOAD_CRC_ERROR_MASK) == 0:
if self._on_receive:
payload = self.read_payload()
self.set_lock(False) # unlock when done reading
data = aes.decrypt_payload(payload)
self._on_receive(self, data)
self.set_lock(False) # unlock in any case.
self.collect_garbage()