RAK3172 Class C Downlink Example and Pitfalls

Hi All

I am running a RAK3172 ESP32 combo. The ESP32 runs Micropython and talks to the RAK3172 over UART. This all works fine.

However, I cannot get the RAK3172 to receive downlinks in Class C mode. It is as if it stays in Class A. It receives the downlink in the RX windows after an uplink. I would expect it to have the RX window open and receive the downlink anytime when in Class C.

So I need assistance in troubleshooting the setup, as well as understanding how exactly the Class C mode works through the AT command set. Do I have to issue AT+RECV=? to check if something was received, or will the received downlink pop up on the UART. If neither of these, I do I get the receive downlink?

Any ideas and help with be much appreciated!

Best Regards

Welcome to RAK forum @HenroRitchie ,

Assuming that LNS supports Class C and the device was registered to support Class C, you should be able to get downlinks automatically.

No need to send AT+RECV.

It should look like this.


Hi Carlrowan

Thank you for answering. To confirm, the received packets pops up automatically.

The issue I was sitting with was on the LNS. I am using Chirpstack, and after creating a device profile with Class C capability enabled - the device must be reactivated to allow the LNS to send downlinks immediately. It also helps to confirm all the settings in the device profile is correct.