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Node parameters

When configuring a node, it is necessary to set some parameters which will be used lately in the network, and some parameters needed for using the API functions.

Node address

Each module must have a unique address of 8 bits.
It identifies uniquely a node inside a network. It is necessary to assign the address value each time the module is set on.
The node address 0 and the node address 1 are reserved to broadcast communication and to the network central node respectively. In order to respect this, users must assign the node address 1 to the module in the central node and node addresses from 2 to 255 to all the other nodes in their network. That means a network will consist of:
  • 1 central node. Address value equal to 1
  • Up to 254 nodes. Address values from 2 to 255
The user must not assign the node address 0 to any node since it is reserved to indicate the module we want to perform a broadcast transmission.
Example of use:
{
sx1272.setNodeAddress(2); // Set the Node address into REG_NODE_ADDRESS register
sx1272.getNodeAddress(); // Get the assigned Node address
}
Related variables:
sx1272._nodeAddress → stores the Node address
The module rejects packets destined to other nodes, although it is actually receiving all the packets in the network while it is in receiving state.

Frequency band

There are two frequency bands available to work with this module, 868 MHz and 900 MHz ISM bands. Depending on the country the user is located, one or the other will be chosen. Inside each frequency band there are several channels, so the user can choose among them.
Note: To know what band is legal in your country, please check the ITU region map. Region 1 ISM free band is 868 MHz and Region 2 ISM free band is 900 MHz. You must also check the legal restrictions by region to use the proper configuration and channel. It is the responsibility of the users to know the allowed frequency band and channels in their country, and use them. Ignoring this, could lead to considerable penalties.

Channel

This parameter defines the frequency channel used by the module to transmit and receive.
There are 8 channels defined to be used in the 868 MHz band and 13 channels to be used in the 900 MHz band. They can be observed in the following figures.
Figure: Frequency channels in the 868 MHz band
Figure: Frequency channels in the 900 MHz band
Channel Number
Central frequency
Channel Number
Central frequency
CH_10_868
865.20 MHz
CH_00_900
903.08 MHz
CH_11_868
865.50 MHz
CH_01_900
905.24 MHz
CH_12_868
865.80 MHz
CH_02_900
907.40 MHz
CH_13_868
866.10 MHz
CH_03_900
909.56 MHz
CH_14_868
866.40 MHz
CH_04_900
911.72 MHz
CH_15_868
866.70 MHz
CH_05_900
913.88 MHz
CH_16_868
867 MHz
CH_06_900
916.04 MHz
CH_17_868
868 MHz
CH_07_900
918.20 MHz
CH_08_900
920.36 MHz
CH_09_900
922.52 MHz
CH_10_900
924.68 MHz
CH_11_900
926.84 MHz
CH_12_900
915 MHz
Figure: Channels used by the LoRa module in 868 MHz and 900 MHz
Example of use:
{
sx1272.setChannel(CH_00_900); // Set channel
sx1272.getChannel(); // Get Channel
}
Related variables:
sx1272._channel → stores the operating channel
SX1272 configuration example: