Read meta-information from ACK-Packet (Arduino LMIC)

End Devices (Nodes) LMIC
1

Hello,

is it possible to read meta-information from ACK-Packet?

Specifically, I want that the Node (TTGO LoRa V2.1) can get the infos “channel”; “rssi” and “snr” from a LoRaWAN-Link.

Greetings

E_T

2

Hi,
see RadioDriver.md which describes the fields LMIC.snr, LMIC.rssi, LMIC.rps and LMIC.freq which hold these information. They can be accessed in the event handler for a EV_TXCOMPLETE event. As I have not tested this before, I can not guarantee that this works.
Also the rx channel is predtermined, see here for example.

4 Likes
3

Hello Ludwig,

thank you, i will try it.

Greetings

E_T

1 Like
4

Hello,

i have a second question:

I get a EV_TXCOMPLETE, but get no “Received ack” (ABP)

case EV_TXCOMPLETE:
Serial.println(F(“EV_TXCOMPLETE (includes waiting for RX windows)”));
if (LMIC.txrxFlags & TXRX_ACK)
{
Serial.println(F(“Received ack”));
…

Must i take OTAA?
Greetings

E_T

5

Hello E_T,
you should only get a TXRX_ACK, if you sent a confirmed uplink and received a confirmation. This can be requested with a flag in LMIC_setTxData2 (u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed). I would advise against using this too often as it requires the gateway to transmit. During this time it can not receive messages and this also counts towards the gateways dutycycle.

You can also invoke a downlink by sending to the device. For example you can do this with the DOWNLINK field in your end devices configuration in the TTN console.

This should be independent of your activation method. Though OTAA is preferred.

See also https://www.thethingsnetwork.org/docs/lorawan/limitations.html#sending-responses-from-your-application-to-your-node-downlink .

Best regards

6

Any node is allowed max 10 downlinks (ack or regular downlink data packets) each day in TTN community network, so limiting downlinks is necessary anyway.

7

Hello Ludwig,

thank you very much for the hint!

Greetings
E_T

1 Like
8

Hello Jac Kersing,

thank you, I will keep that in mind.

Greetings

E_T