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End Node  downlink problem

Question asked by Saar Eliad on Jun 11, 2018
Latest reply on Jun 18, 2018 by Gidi M

Hi,

We are working on a LoRa project using the NUCLEO-L073RZ +SX1272MB2DAS and the end-node application (from STM32CubeExpansion_LRWAN_V1.1.5) On region EU868.

We use the end node with ABP and static network_key which is configured also in the server application.

 

Our gateway is composed of raspberry-pi and an SX1272MB2DAS LoRa RF expansion board. This is a single channel gateway, it receives/sends packets only on frequency 868.5 with datarate 0 (bandwitdh=125, spreading_factor=12), hence, we have configured the rx_window2 with the same frequency and datarate.

 

The gateway receives a LoRa packet from the end node and sends it to the server.

Then the gateway sends a downlink packet which came from the server.

The end node never gets this packet.

The time between the gateway's uplink reception and downlink transmission is around 10.5 seconds.

 

We tried to use CLASS_A and CLASS_C with different rx delays and receive windows but the end node didn't get the downlink packet (rx timeout).

When placing another NUCLEO board which runs the PingPong application, it does receive the downlink message from the gateway successfully.

 

We guess that the end node doesn't receive the downlink messages because of a timing issue, but can't be sure. (as we also tried using class C…)

Can it be a different cause?

How can we overcome this?

 

Regards,

Saar and Guy.

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