Raspberry gateway with 2 sx1278

[zaiplanet]

Hi sir! I running this project on raspberry 3B+ gateway with 1 sx1278 and 2 node also use sx1278. But while 2 node transmit same time to gateway, gw only received 1 packet from 1 node. Can we set one more sx1278 on second spi on raspberry, sir? Sorry about my english

[CongducPham]

It is theoretically possible but managing both radio modules is very tricky. In your scenario, you may have packet collision. You may need to implement simple listen-before-mechanism with random back-off procedure to limit packet collision.

regards,

[zaiplanet]

Ok sir. Thank u sir

[zaiplanet]

How i can enable LBT at nodes with sx1278, sir?

[CongducPham]

You have to implement it yourself using LoRa's CAD mechanism. You can have a look at our modified SX12XX lib and look at the CarrierSense function: https://github.com/CongducPham/LowCostLoRaGw/blob/9f930cdc8393c5bc76e901757c07bcde70f588f2/Arduino/libraries/SX12XX/src/SX127XLT.cpp#L6224

[zaiplanet]

Thank you very much, sir I'll check it 👍

[zaiplanet]

hi sir, gateway can send request then node reply?

[CongducPham]

That can be done through a downlink message from the gateway, then the node would decide to send something following the reception of the downlink. regards,