class LoRa

This class provides a driver for the LoRa network processor in the LoPy and FiPy. Below is an example demonstrating LoRaWAN Activation by Personalisation usage:

from network import LoRa
import socket
import binascii
import struct

# Initialize LoRa in LORAWAN mode.
lora = LoRa(mode=LoRa.LORAWAN)

# create an ABP authentication params
dev_addr = struct.unpack(">l", binascii.unhexlify('00 00 00 05'.replace(' ','')))[0]
nwk_swkey = binascii.unhexlify('2B 7E 15 16 28 AE D2 A6 AB F7 15 88 09 CF 4F 3C'.replace(' ',''))
app_swkey = binascii.unhexlify('2B 7E 15 16 28 AE D2 A6 AB F7 15 88 09 CF 4F 3C'.replace(' ',''))

# join a network using ABP (Activation By Personalization)
lora.join(activation=LoRa.ABP, auth=(dev_addr, nwk_swkey, app_swkey))

# create a LoRa socket
s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)

# set the LoRaWAN data rate
s.setsockopt(socket.SOL_LORA, socket.SO_DR, 5)

# make the socket non-blocking
s.setblocking(False)

# send some data
s.send(bytes([0x01, 0x02, 0x03]))

# get any data received...
data = s.recv(64)
print(data)

Please ensure that there is an antenna connected to your device before sending/receiving LoRa messages as inproper use (e.g. without an antenna), may damage the device.

Additional Examples

For various other complete LoRa examples, check here for additional examples.

Constructors

class network.LoRa(id=0, ...)

Create and configure a LoRa object. See init for params of configuration.

lora = LoRa(mode=LoRa.LORAWAN)

Methods

lora.init(mode, * , frequency=868000000, tx_power=14, bandwidth=LoRa.BW_125KHZ, sf=7, preamble=8, coding_rate=LoRa.CODING_4_5, power_mode=LoRa.ALWAYS_ON, tx_iq=False, rx_iq=False, adr=False, public=True, tx_retries=1, device_class=LoRa.CLASS_A)

This method is used to set the LoRa subsystem configuration and to specific raw LoRa or LoRaWAN.

The arguments are:

  • mode can be either LoRa.LORA or LoRa.LORAWAN.
  • frequency accepts values between 863000000 and 870000000 in the 868 band, or between 902000000 and 928000000 in the 915 band.
  • tx_power is the transmit power in dBm. It accepts between 2 and 14 for the 868 band, and between 5 and 20 in the 915 band.
  • bandwidth is the channel bandwidth in KHz. In the 868 band the accepted values are LoRa.BW_125KHZ and LoRa.BW_250KHZ. In the 915 band the accepted values are LoRa.BW_125KHZ and LoRa.BW_500KHZ.
  • sf sets the desired spreading factor. Accepts values between 7 and 12.
  • preamble configures the number of pre-amble symbols. The default value is 8.
  • coding_rate can take the following values: LoRa.CODING_4_5, LoRa.CODING_4_6, LoRa.CODING_4_7 or LoRa.CODING_4_8.
  • power_mode can be either LoRa.ALWAYS_ON, LoRa.TX_ONLY or LoRa.SLEEP. In ALWAYS_ON mode, the radio is always listening for incoming - packets whenever a transmission is not taking place. In TX_ONLY the radio goes to sleep as soon as the transmission completes. In SLEEP mode the radio is sent to sleep permanently and won’t accept any commands until the power mode is changed.
  • tx_iq enables TX IQ inversion.
  • rx_iq enables RX IQ inversion.
  • adr enables Adaptive Data Rate.
  • public selects between the public and private sync word.
  • tx_retries sets the number of TX retries in LoRa.LORAWAN mode.
  • device_class sets the LoRaWAN device class. Can be either LoRa.CLASS_A or LoRa.CLASS_C.

In LoRa.LORAWAN mode, only adr, public, tx_retries and device_class are used. All the other params will be ignored as they are handled by the LoRaWAN stack directly. On the other hand, in LoRa.LORA mode from those 4 arguments, only the public one is important in order to program the sync word. In LoRa.LORA mode adr, tx_retries and device_class are ignored since they are only relevant to the LoRaWAN stack.

For example, you can do:

# initialize in raw LoRa mode
lora.init(mode=LoRa.LORA, tx_power=14, sf=12)

or:

# initialize in LoRaWAN mode
lora.init(mode=LoRa.LORAWAN)
lora.join(activation, auth, * ,timeout=None, dr=None)

Join a LoRaWAN network. Internally the stack will automatically retry every 15 seconds until a Join Accept message is received. The parameters are:

  • activation: can be either LoRa.OTAA or LoRa.ABP.
  • auth: is a tuple with the authentication data.
  • timeout: is the maximum time in milliseconds to wait for the Join Accept message to be received. If no timeout (or zero) is given, the call returns immediatelly and the status of the join request can be checked with lora.has_joined().
  • dr: is an optional value to specify the initial data rate for the Join Request. Possible values are 0 to 5 for EU868, or 0 to 4 for US915.

In the case of LoRa.OTAA the authentication tuple is: (app_eui, app_key). Example:

from network import LoRa
import socket
import time
import binascii

# Initialize LoRa in LORAWAN mode.
lora = LoRa(mode=LoRa.LORAWAN)

# create an OTAA authentication parameters
app_eui = binascii.unhexlify('AD A4 DA E3 AC 12 67 6B'.replace(' ',''))
app_key = binascii.unhexlify('11 B0 28 2A 18 9B 75 B0 B4 D2 D8 C7 FA 38 54 8B'.replace(' ',''))

# join a network using OTAA (Over the Air Activation)
lora.join(activation=LoRa.OTAA, auth=(app_eui, app_key), timeout=0)

# wait until the module has joined the network
while not lora.has_joined():
    time.sleep(2.5)
    print('Not yet joined...')

In the case of LoRa.ABP the authentication tuple is: (dev_addr, nwk_swkey, app_swkey). Example:

from network import LoRa
import socket
import binascii
import struct

# Initialize LoRa in LORAWAN mode.
lora = LoRa(mode=LoRa.LORAWAN)

# create an ABP authentication params
dev_addr = struct.unpack(">l", binascii.unhexlify('00 00 00 05'.replace(' ','')))[0]
nwk_swkey = binascii.unhexlify('2B 7E 15 16 28 AE D2 A6 AB F7 15 88 09 CF 4F 3C'.replace(' ',''))
app_swkey = binascii.unhexlify('2B 7E 15 16 28 AE D2 A6 AB F7 15 88 09 CF 4F 3C'.replace(' ',''))

# join a network using ABP (Activation By Personalization)
lora.join(activation=LoRa.ABP, auth=(dev_addr, nwk_swkey, app_swkey))
lora.bandwidth([bandwidth])

Get or set the bandwidth in raw LoRa mode (LoRa.LORA). Can be either LoRa.BW_125KHZ (0), LoRa.BW_250KHZ (1) or LoRa.BW_500KHZ (2):

# get raw LoRa Bandwidth
lora.bandwidth()

# set raw LoRa Bandwidth
lora.bandwidth(LoRa.BW_125KHZ)
lora.frequency([frequency])

Get or set the frequency in raw LoRa mode (LoRa.LORA). The allowed range is between 863000000 and 870000000 Hz for the 868 MHz band version or between 902000000 and 928000000 Hz for the 915 MHz band version.:

# get raw LoRa Frequency
lora.frequency()

# set raw LoRa Frequency
lora.frequency(868000000)

lora.coding_rate([coding_rate]) Get or set the coding rate in raw LoRa mode (LoRa.LORA). The allowed values are: LoRa.CODING_4_5 (1), LoRa.CODING_4_6 (2), LoRa.CODING_4_7 (3) and LoRa.CODING_4_8 (4).

# get raw LoRa Coding Rate
lora.coding_rate()

# set raw LoRa Coding Rate
lora.coding_rate(LoRa.CODING_4_5)
lora.preamble([preamble])

Get or set the number of preamble symbols in raw LoRa mode (LoRa.LORA):

# get raw LoRa preamble symbols
lora.preamble()

# set raw LoRa preamble symbols
lora.preamble(LoRa.CODING_4_5)
lora.sf([sf])

Get or set the spreading factor value in raw LoRa mode (LoRa.LORA). The minimum value is 7 and the maximum is 12:

# get raw LoRa spread factor value
lora.sf()

# set raw LoRa spread factor value
lora.sf(7)
lora.power_mode([power_mode])

Get or set the power mode in raw LoRa mode (LoRa.LORA). The accepted values are: LoRa.ALWAYS_ON, LoRa.TX_ONLY and LoRa.SLEEP:

lora.stats()

Return a named tuple with useful information from the last received LoRa or LoRaWAN packet. The named tuple has the following form:

(rx_timestamp, rssi, snr, sftx, sfrx, tx_trials)

Example:

lora.stats()

Where:

  • rx_timestamp is an internal timestamp of the last received packet with microseconds precision.
  • rssi holds the received signal strength in dBm.
  • snr contains the signal to noise ratio id dB (as a single precision float).
  • sfrx tells the data rate (in the case of LORAWAN mode) or the spreading factor (in the case of LORA mode) of the last packet received.
  • sftx tells the data rate (in the case of LORAWAN mode) or the spreading factor (in the case of LORA mode) of the last packet transmitted.
  • tx_trials is the number of tx attempts of the last transmitted packet (only relevant for LORAWAN confirmed packets).
lora.has_joined()

Returns True if a LoRaWAN network has been joined. False otherwise.:

lora.add_channel(index, * , frequency, dr_min, dr_max)

Add a LoRaWAN channel on the specified index. If there’s already a channel with that index it will be replaced with the new one.

The arguments are:

  • index: Index of the channel to add. Accepts values between 0 and 15 for EU and between 0 and 71 for US.
  • frequency: Centre frequency in Hz of the channel.
  • dr_min: Minimum data rate of the channel (0-7).
  • dr_max: Maximum data rate of the channel (0-7).

Examples:

lora.add_channel(index=0, frequency=868000000, dr_min=5, dr_max=6)
lora.remove_channel(index)

Removes the channel from the specified index. On the 868MHz band the channels 0 to 2 cannot be removed, they can only be replaced by other channels using the lora.add_channel method. A way to remove all channels except for one is to add the same channel, 3 times on indexes 0, 1 and 2. An example can be seen below:

lora.remove_channel()

On the 915MHz band there are no restrictions around this.

lora.mac()

Returns a byte object with the 8-Byte MAC address of the LoRa radio.

lora.callback(trigger, handler=None, arg=None)

Specify a callback handler for the LoRa radio. The trigger types are LoRa.RX_PACKET_EVENT, LoRa.TX_PACKET_EVENT and LoRa.TX_FAILED_EVENT

The LoRa.RX_PACKET_EVENT event is raised for every received packet. The LoRa.TX_PACKET_EVENT event is raised as soon as the packet transmission cycle ends, which includes the end of the receive windows (even if a downlink is received, the LoRa.TX_PACKET_EVENT will come last). In the case of non-confirmed transmissions, this will occur at the end of the receive windows, but, in the case of confirmed transmissions, this event will only be raised if the ack is received. If the ack is not received LoRa.TX_FAILED_EVENT will be raised after the number of tx_retries configured have been performed.

An example of how this callback functions can be seen the in method lora.events().

lora.ischannel_free(rssi_threshold)

This method is used to check for radio activity on the current LoRa channel, and if the rssi of the measured activity is lower than the rssi_threshold given, the return value will be True, otherwise False. Example:

lora.ischannel_free(-100)
lora.set_battery_level(level)

Set the battery level value that will be sent when the LoRaWAN MAC command that retrieves the battery level is received. This command is sent by the network and handled automatically by the LoRaWAN stack. The values should be according to the LoRaWAN specification:

  • 0 means that the end-device is connected to an external power source.
  • 1..254 specifies the battery level, 1 being at minimum and 254 being at maximum.
  • 255 means that the end-device was not able to measure the battery level.
lora.set_battery_level(127)    # 50% battery
lora.events()

This method returns a value with bits sets (if any) indicating the events that have triggered the callback. Please note that by calling this function the internal events registry is cleared automatically, therefore calling it immediately for a second time will most likely return a value of 0.

Example:

def lora_cb(lora):
    events = lora.events()
    if events & LoRa.RX_PACKET_EVENT:
        print('Lora packet received')
    if events & LoRa.TX_PACKET_EVENT:
        print('Lora packet sent')

lora.callback(trigger=(LoRa.RX_PACKET_EVENT | LoRa.TX_PACKET_EVENT), handler=lora_cb)
lora.nvram_save()

Save the LoRaWAN state (joined status, network keys, packet counters, etc) in non-volatile memory in order to be able to restore the state when coming out of deepsleep or a power cycle.

lora.nvram_save()
lora.nvram_restore()

Restore the LoRaWAN state (joined status, network keys, packet counters, etc) from non-volatile memory. State must have been previously stored with a call to nvram_save before entering deepsleep. This is useful to be able to send a LoRaWAN message immediately after coming out of deepsleep without having to join the network again.

lora.nvram_restore()

Constants

LoRa.LORA LoRa.LORAWAN LoRa stack mode

LoRa.OTAA LoRa.ABP LoRaWAN join procedure

LoRa.ALWAYS_ON LoRa.TX_ONLY LoRa.SLEEP Raw LoRa power mode

LoRa.BW_125KHZ LoRa.BW_250KHZ LoRa.BW_500KHZ Raw LoRa bandwidth

LoRa.CODING_4_5 LoRa.CODING_4_6 LoRa.CODING_4_7 LoRa.CODING_4_8 Raw LoRa coding rate

LoRa.RX_PACKET_EVENT LoRa.TX_PACKET_EVENT LoRa.TX_FAILED_EVENT Callback trigger types (may be ORed)

LoRa.CLASS_A LoRa.CLASS_C LoRaWAN device class

Working with LoRa and LoRaWAN Sockets

LoRa sockets are created in the following way:

import socket
s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)

And they must be created after initialising the LoRa network card.

LoRa sockets support the following standard methods from the socket module:

socket.close()

Usage:

s.close()
socket.bind(port_number)

Usage:

s.bind(1)

The bind() method is only applicable when the radio is configured in LoRa.LORAWAN mode.

socket.send(bytes)

Usage:

s.send(bytes([1, 2, 3]))

or:

s.send('Hello')
socket.recv(bufsize)

Usage:

s.recv(128)
socket.recvfrom(bufsize)

This method is useful to know the destination port number of the message received. Returns a tuple of the form: (data, port)

Usage:

s.recvfrom(128)
socket.setsockopt(level, optname, value)

Set the value of the given socket option. The needed symbolic constants are defined in the socket module (SO_* etc.). In the case of LoRa the values are always integers. Examples:

# configuring the data rate
s.setsockopt(socket.SOL_LORA, socket.SO_DR, 5)

# selecting non-confirmed type of messages
s.setsockopt(socket.SOL_LORA, socket.SO_CONFIRMED, False)

# selecting confirmed type of messages
s.setsockopt(socket.SOL_LORA, socket.SO_CONFIRMED, True)

Socket options are only applicable when the LoRa radio is used in LoRa.LORAWAN mode. When using the radio in LoRa.LORA mode, use the class methods to change the spreading factor, bandwidth and coding rate to the desired values.

socket.settimeout(value)

Sets the socket timeout value in seconds. Accepts floating point values.

Usage:

s.settimeout(5.5)
socket.setblocking(flag)

Usage:

s.setblocking(True)

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