How to configure radioFSK for Lora FSK channel (EU)

[tauesdospi]

Hi,

I have been trying to use the FSK mode of the lorawan stack for some FSK communication but it seems there are too my bugs and strange this so I'm giving up.

I'm new to RadioLib and trying to configure the radioFSK in order to communicate using the FSK channel specs defined in the Lorawan EU channel map.

I know these paramenters and configuring the lora fsk with this I'm able to send/receive packets from a Lorawan gateway using the FSK channel

#define FSK_FREQ xxx // Hz
#define FSK_FDEV 25000 // Hz
#define FSK_DATARATE 50000 // bps
#define FSK_BANDWIDTH 50000 // Hz
#define FSK_AFC_BANDWIDTH 83333 // Hz
#define FSK_PREAMBLE_LENGTH 5 // Same for Tx and Rx
#define FSK_FIX_LENGTH_PAYLOAD_ON false

I have tried this in RadioLib

SX1276 radio = new Module(GPIO_NUM_18, GPIO_NUM_26, GPIO_NUM_14, GPIO_NUM_35);
radio.beginFSK(868.8, 50, 25, 83.3, 17, , false);

I guess I'm missing several things (syncwords? others? ) as Radiolib is a generic all-purpourse lib and the lorawan fsk functions are directed to work only with their specs.

I will appreciate any help on how to setup RadioLib to be able to comunicate to Lorawan EU868 FSK channels.

Thank you
Antonio

[jgromes]

At the moment, LoRaWAN support in RadioLib is still work-in-progress. The node starts in LoRa mode, and because adaptive data rate was not yet implemented, the node will never enter the FSK channels. So for now, there's no support for LoRaWAN FSK channels, though it is being worked on.

However, as far as I understand LoRaWAN, you don't really select that you want to use the FSK channel, instead it will be the highest possible transfer speed when using the adaptive data rate feature. Though it is possible I am mistaken, and if you perform OTA activation on the FSK channel with ADR disabled, the node will remain there. Guess I can test this

[tauesdospi]

Exactly... lots of commercial lorawan gateways are sx130x concentrators with the packet forwarder software.. like mikrotik wap lora, multitech conduit, etc.. some more expensive also have the lorawan stack and network server inside (eg. milesight) but all of the can be communicated directly by the packet-forwarder protocol.

Thanks for your time! I will continue investigating in order to figure what set of parameters are required to communicate to the FSK channel of such radios... It should be specified at some place as it is standarized across all lorawan gateways but I can't find it.. Will let you know !

Best regards
Antonio

[tauesdospi]

got it ! I'm posting it here in case anybody else requires this at some point:

This setup permits raw FSK tx/rx with any lorawan gateway (packet-forwarder) in EU region. For other regions frequency and some other parameter may change.

radio.beginFSK();
radio.setFrequency(868.8); // this is the standarized EU868 Lorawan FSK channel
radio.setBitRate(50.0);
radio.setFrequencyDeviation(25);
radio.setRxBandwidth(50.0);
radio.setOutputPower(17.0); // or your power
radio.setCurrentLimit(100); // may not be required
radio.setDataShaping(RADIOLIB_SHAPING_1_0);
uint8_t syncWord[] = {0xC1, 0x94, 0xC1 };
radio.setSyncWord(syncWord, 3);
radio.disableAddressFiltering();
radio.setEncoding(RADIOLIB_ENCODING_WHITENING);
radio.setCRC(true);
radio.variablePacketLengthMode();

[jgromes]

Thanks for poisting the parameters - this gives me an idea that I could extend the LoRaWAN implementation to allow FSK usage for non-LoRa modules. So one could connect plain old FSK transceiver to a LoRaWAN network, that would be rather interesting.

[jgromes]

@tauesdospi where did you find the frequency for the EU868 FSK channel? It's not listed in the 1.1 regional parameters document.

[tauesdospi]

It is noted in several places eg. https://www.thethingsnetwork.org/docs/lorawan/frequency-plans/

the exact parameters to use it are:

state = radio.beginFSK();
state = radio.setFrequency(868.8);
state = radio.setBitRate(50.0);
state = radio.setFrequencyDeviation(25);
state = radio.setRxBandwidth(50.0);
state = radio.setAFCBandwidth(83.3);
state = radio.setDataShaping(RADIOLIB_SHAPING_1_0);
uint8_t syncWord[] = {0xC1, 0x94, 0xC1 };
state = radio.setSyncWord(syncWord, 3);
state = radio.setPreambleLength(40);
state = radio.disableAddressFiltering();
state = radio.setEncoding(RADIOLIB_ENCODING_WHITENING);
state = radio.setCRC(true);
state = radio.variablePacketLengthMode();

regards
Antonio