Use a different SF?

[gaijinsr]

Hi,
in line 67 of radio-mailbox/03_lora_test/lib/RFM95/RFM95.cpp there is

//Spreading factor 7, PayloadCRC On
RFM_Write(0x1E,0xB4);

My gateway receives the packages with SF7 as expected - or rather not:
From the documentation of the chip I understand that bits 4-7 of the 1E register
(i.e. the higher hex digit) give the SF, so I would expect the SF to be B=11 and
not 7... How can I use a larger SF (for longer range)?

Best, Stefan

[gaijinsr]

Hi, to answer my own question: I was mislead: Register 1E is set to this strange value only during initialization, when the packet is actually sent (line 243), it does
RFM_Write(0x1E,0x74); //SF7 CRC On
and there is the 7 that I expected. Changing this to 9 really makes the module use SF9.

What also took me quite some time to find out: LoRaWan jumps between channels (see lines 193ff),
so if you use a cheap 1-channel gateway with an ESP and a single RFM95, you will only receive a fraction
of the packets. By commenting out the channel hopping I was able to receive all my packets.