Communication between an E32-900T20D and RFM95W

[ezcGman]

Hey there,

after I finally got my module up working, I continued on actually getting my two LoRa modules to talk with each other. But to be honest, I’m lost yet again and overwhelmed with all the information and (honestly) not so clear examples to me.

So my two modules and goals are:
– E-Byte E32-900T20D (with an antenna attached to the SMA jack): This module should only listen for packages; it will be a simple gateway basically.
– HopeRF RFM95W (with a wire sodlered to it as an antenna: This module should only send packages; they will be installed into various sensors I have.
=> So I ultimately want to do a “fixed transmission”, as every RFM95W always directly talks to the E32. But I’m fine with having them at least communicate for now in ANY way…

My first tests were just leaving all the default config for both modules as they are, just setting the frequency on both sides to 868MHz and send a message. Obviously, this doesn’t work, as in: the RFM95W successfully sends the message, but my E32 module never receives something…
So something must still be off between those two.
I of course tested sending and receiving with two RFM95W and that does work. So *generally* sending data works.

So I tried setting the E32 to broadcast mode using your tutorials ad also tried switching off FEC (tried wit and without FEC):

configuration.ADDL = BROADCAST_ADDRESS;
configuration.ADDH = BROADCAST_ADDRESS;
configuration.OPTION.fec = FEC_0_OFF;

I validated the response to setConfiguration included my changed settings, so I expect them saved.
Unfortunately still nothing: My RFM95W apparently sending packages, nothing received on the E32…

I think I understood how the E32 LoRa module communication works, at least that it’s a matter of address and channel who will receive the data I send. The address (seems to be) defined by ADDH(igh) & ADDL(ow). The channel seems to also effect the frequency that is used. So setting the frequency with #define FREQUENCY_868 actually sets it to 862 and with my channel set to 6, it actually uses my desired 868MHz. So if I understand it right, changing the channel to 4 would make the module communicate on 866MHz!? However, I need 868MHz.

Witout setting it to broadcast mode, my default settings are:
AddH BIN: 0
AddL BIN: 0
Chan BIN: 6 -> 868MHz

So I think I understood that side of the cake. But I can’t make it to receive what the RFM95W sends… Actually, your / the E32 is way better documented and understandable than the RFM95W and the famous Arduino lib to use it: https://github.com/sandeepmistry/arduino-LoRa. This lib/the RFM95W doesn’t have any ADDL/ADDH nor channel I can configure… It has a “sync word” which I still didn’t fully understand how it’s part of the whole sending/receiving process. Also setting the frequency is utterly complicated, split over three bits with a weird formula behind it… I can’t even figure out the *exact* frequency when I set it to 868E6…

I’m not asking you to understand how this lib works, but: This RFM95W is a *very* common module, so is this lib. I’m just wondering if you ever got an E-Byte and RFM95W to successfully communicate with each other, or if you have a hint where I could start searching what the issue is…

Thanks again for your help and greetings,

Andy!

[Renzo Mischianti]

Hi ezcGman,
I think the two modules can’t be compatible.
RFM95W is a basic lora module, e32 is more complex, have a specified protocol with data criptyng, WOR, addressing and other features.
Bye Renzo

[ezcGman]

Ah man, that’s sad… I also did some crawling through issues on “the other side” and it seems people have been able to mock what the e32 sends and receive it on an rfm95w, but not other way around…

That’s super sad 🙁 Just getting into LoRa and seeing that different modules for the same tech can’t communicate is pretty sad 🙁

Will probably go for the RFM95W then, as it’s cheaper and if I gonna do multiple sensors, this will quickly add up :/

Still, the E32 and your lib just feel… better!

Thanks for the help and greetings,

Andy!

[ezcGman]

I gave it one more try:

So the E32 uses the Semtech SX1267 or 78. The RFM95W is a copy of the SX1276. So theoretically, if I would be able to control the chip directly via SPI and not via the UART “bridge”, I should be able to use the Arduino Lora lib…

I looked through the E-Byte website, but couldn’t really find a module that exposes the SPI interface. Are you aware of any? :/ Maybe I overlooked something. Thx!

[Renzo Mischianti]

If I remember exists an e32 SPI version, but if you want something with good performance and less price you must get Ebyte E220.

It has a configurable encrypting key, WOR, RSSI etc. etc. module format and SMD.

I’ll release the definitive version of the library soon, here a preview
Ebyte E220 (LLCC68) compatibility

Bye Renzo

[ezcGman]

For which ones are you planning to add support? The UART versions (E220-900T*S/D) or the SPI versions (E220-900M*S)? Just curious 🙂

[Renzo Mischianti]

Always UART version.
I want to create other libraries to use with Android and Python or java. But I need more time.
Bye Renzo

[ezcGman]

Gotcha! I gonna go shopping now 🙂

[ezcGman]

Will check on those links later, thx!

But quick question already: Will I be able to communicate with RFM95W modules with the E220?

The E32 SPI looks like it could work with the arduino-lora lib, hence I can have a quality module as a gateway working with the RFM95W has cheap alternatives for the sensors 🙂

[Renzo Mischianti]

I think It’s not possible, but the price of LoRa E220 it’s the same as RFM95W so you can use only that.
I don’t know if E32 SPI can communicate with RFM95W.
Bye Renzo

[ezcGman]

Thx man! I’ll check it out!

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