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README.md

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LoRaWAN region switching demonstration

Description

The application will automatically starts a procedure to join a LoRaWAN network (see configuration).

Once a network is joined (i.e. when the corresponding event is triggered), uplinks are sent on a regular basis on port LORAWAN_APP_PORT. The content of the uplink is the value read out from the temperature sensor available through smtc_modem_hal_get_temperature().

After each uplink, the application checks the number of consecutive uplinks without downlink thanks to smtc_modem_lorawan_get_lost_connection_counter(). If this value is higher or equal to LORAWAN_MAX_LOST_CONNECTION_CNT_BEFORE_LINK_CHECK, the application start requesting link check with smtc_modem_lorawan_request_link_check(). As soon as there are LORAWAN_MAX_LINK_CHECK_KO_BEFORE_SWITCH unanswered link checks, the application automatically leave the network and start joining a 2.4GHz network. For demonstration purpose, this behavior can be forced by pushing on the button of the dev kit board: the region switching will be done immediately.

Once a 2.4GHz network is joined, the application takes sending uplinks up again - as done previously. The difference is that the device will remain connected to this network until a properly formatted downlink is received on port LORAWAN_APP_PORT. When this downlink is received, the application switch back to the initial region.

Configuration

Several parameters can be updated in main_region_switching.h header file:

Constant Description Possible values Default Value
LORAWAN_APP_PORT LoRaWAN FPort used for uplink and downlink messages [1, 223] 2
LORAWAN_MAX_LOST_CONNECTION_CNT_BEFORE_LINK_CHECK Number of uplink without downlink before link check [1, 255] 10
LORAWAN_MAX_LINK_CHECK_KO_BEFORE_SWITCH Number of unanswered link check before region switch [1, 255] 4
LORAWAN_MAX_LINK_CHECK_KO_BEFORE_SWITCH Number of unanswered link check before region switch [1, 255] 4
APP_MODEM_REGION_SWITCHING_OPCODE Opcode of the region switching command [0x00, 0xFF] 0x70
join_eui_2g4 JoinEUI to be used when joining the 2.4GHz network

When compiling with arm-none-eabi-gcc toolchain, all these constant are configurable through command line with the EXTRAFLAGS. See README.md.

Expected Behavior

Here follow the steps that shall be seen in logs to indicate the expected behavior of the application:

Device starts and reset

INFO: Modem Initialization
INFO: ###### ===== LoRa Basics Modem region switching demonstration ==== ######
INFO: ###### ===== BASICS MODEM RESET EVENT ==== ######

Following this print you shall find application and LoRaWAN parameters prints

Device joined the network

INFO: ###### ===== JOINED EVENT ==== ######

Push button event occurred, generating uplink

INFO: ###### ===== BUTTON PUSH ==== ######
INFO: Request uplink

Send done

INFO: ###### ===== TX DONE EVENT ==== ######

Shall follow a consistant number of uplinks

INFO: Uplink count: 1

Known limitations

Join Nonce shared between networks

The value of the Join nonce used to compare to the one sent by the LNS in the join accept message is not specific to one of the network the device will join in this demonstration: it is actually the same value. Due to that implementation, the first join accept received when switching from one network to another will be rejected.