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Using LoRa (transparent transmission) by Ebyte as UART radio


(Lapo Minni) #1

Dears,
I am using two emlid reach M+ since Augst as RTK device for field sampling.
I started using two cheap 3DR radio:" RS232 TTL UART Wireless Transceiver Module for Arduino DUE MEGA2560 3DR Radio" to allow communication between the rover and the base. [here you can find the description : https://www.ebay.com/itm/2x-RS232-TTL-UART-Wireless-Transceiver-Module-for-Arduino-DUE-MEGA2560-3DR-Radio/282722771557?hash=item41d3972265:g:nqYAAOSwjzJbDDTW:rk:3:pf:0]
Everything works fine. I linked the S1 using the red, black, yellow and blue pin in VCC,GND,TXD and RXD.

Then, I tried to substitute the 3RD radio with two more powerful LoRa module: E32-915T30D by Ebyte. The two modules are 1W wireless transceiver modules with LoRa spread-spectrum technology, operates at 900~931MHz, based on original imported RFIC SX1276 from SEMTECH, transparent transmission is available, TTL level. [ the manual is available here: http://www.ebyte.com/en/downpdf.aspx?id=174]

So, I supposed that just connecting the pin: VCC, GND, TXD, and RXD in the same order as the 3rd Radio, and as suggested by the DOCS (red, black, yellow and blue), and respecting the default setting of the two device (9600 baud rate) it could work. But I was wrong.
I tried all the baud rate in couple (base and rover), but it doesn’t work in any configuration.

I am not very into electronics and informatics, So I tried to google a bit, but seems nobody used two LoRa (not the emlid ones) as a transceiver to connect two emlid M+ for RTK purpose. That makes me think, it can’t work.
I tried to use PuTTY and filezilla to find the LoRA module as a device connected to the M+, /dev/ttyMFD2. to see if it is possible to check if it is working or not,
I can connect only to the M+, but I can’t find the device folder.

So now I am in a culdesac.
-Someone think it could be possible to set the external LoRa, connected to two M+, to start communicating with each other?
-In case is possible to set the LorA module through the M+ /dev/ttyMFD2?
-Are there any guides to follow?

I hope to have given some useful information for the community and that someone can give some advice or indications.
My best regards to everybody
Stefano


#2

Serial radios can be tricky sometimes. You need several things to match:

  • voltage levels for the signals must match between devices
    • TTL: 3.3V or 5V
    • RS232: +/-25V
  • signal wires must be connected properly: TX - > RX
  • power supply must provide enough current for both devices
    • 2 Amps should be enough for Reach M+ and the Ebyte radio
  • baud rate must match between Reach M+ and Ebyte radio
  • air data rate must match between both Ebyte radios

You have probably checked all those things already, but it is good to check again.

You could get 2 USB/TTL serial converters and a 2 Amp USB hub. Then plug both radios into one computer and see if you can send data to one serial port, through the sending radio, to the receiving radio, and back in the other serial port. Once you have confirmed that the radios are talking to each other, then connecting the transmitting radio to your Reach M+ base station and watch for data coming in from the radio. Once you have confirmed that the M+ base station data is passing over the radio link, then connect the receiving radio to the other Reach M+.

If you do that step by step, then it should work.

If you don’t have then USB/TTL serial converters, then later I could help you troubleshoot without them, working with M+/Ebytes and Putty on your computer.


(Timd1971) #3

Has anyone told you lately, you’re a genius bide!

; )


#4

Trust me, the info only comes from being there in the same situation and having to figure out the long and hard way :persevere: that there was a simple answer to the problem at hand :disappointed_relieved:.


(Lapo Minni) #5

Thanks Byde,
tomorrow I can use the USB/TTL serial converter, so I can update.

Best regards
Stefano


(Lapo Minni) #6

HI Bide,
I check using two 2 USB/TTL serial converters that the Ebyte LoRa module are not talking each other.

I connected the two LoRa Ebyte module to the 2 USB/TTL serial converters,
than I plugged in to my PC; than I check if the LoRa and the 2 USB/TTL serial converters were connected using the RF Setting V3.45 (http://74.117.156.195/verify.php?arquivo=RFSettingv3-45.zip) provided by EByte, and both the LoRa module can connect to the Pc and give all information required:
UART rate: 9600;
Parity 8N1
AiRate 2400
Power 30 dBm
FEC enable
Fixed mode Disabled
WOR Timing 250ms
IO mode PushPull
Address: 0
Channel: 15

I checked that both the devices were connected to the two different port (COM4 and COM5) had they were, and that they can give back the information concerning which parameter they were using, and they give back the information using “RF Setting V3.45”.

But when I transmit any data from one module, using prompt of command eg. :
“echo HELLO > COM4”
or
“echo HELLO > COM5”

the other port does not receive any data (I used the Terminal V1.93B by Br@y++ [https://sites.google.com/site/terminalbpp/] to check if data were coming).
I double checked that everything was working properly, substituting the two Lora module with two 3rd radio, (I used successfully with M+) and indeed using the 3rd radio the information flowed from COM4 to COM5 and vice-versa. Receiving data on the Terminal V1.93B program (and seeing the check light on the USB/TTL serial converters properly turning on and off).

Now I know:

  • the two LoRa are working (I checked through the RF Setting V3.45 (http://74.117.156.195/verify.php?arquivo=RFSettingv3-45.zip) at least they can be set.
    -all the parameter for the two LoRA are the same (but I don’t know if they are right, to transmit data)
    -the checking methods work (the 3rd radios checking gave positive results)
    -the two LoRa module do not communicate with each other, but I can’t understand why.

Any idea to set the two Ebyte LoRA module to make it work?

Thanks for your time
I hope now an easy protocol to check if an UART serial radio is working is published :slight_smile:

update:
I left the M0 and M1 pin without any connection, since in the manual is reported that if M0=0, M1=0, it is in transparent mode.
Than I read in a forum (https://forum.arduino.cc/index.php?topic=478078.0)
that when LoRa module is used in an ARDUINO, to set as zero M0 and M1, they would have connected to the ground. So I tried to connected M0 and M1 to the grownd: I linked M0 , M1 with a cable to the GND, but it dosen’t work anyway. Any idea to properly manage the M0, M1 connection to the GND (without using an Arduino)


#7

Good Job :+1:

It looks like you have done all the troubleshooting, and the radios just don’t work which is too bad.

The only thing to suggest is to start by changing 1 setting on both radios, then then continue doing that. Maybe you’ll get some luck.

Also, you might try reversing the TX/RX pins. You never know if they marked them backwards (e.g. TX = this is a transmit pin; or TX = this should be connected to a transmit pin)


(Lapo Minni) #8

Many thanks Bide.

Do you know how much Amper come out from S1 Vdd Gdd when the M+ is powered with a 2.4 Amper from usb?


#9

Yes, I did read that earlier. Sorry for asking again.

I have had trouble with cheap USB power adapters.

Have you tried powering Reach M+ separately from the Ebyte? Or getting an oversized USB power supply might work too (3 Amp +).

I have tried some cheap USB 1 Amp adapters here that will not power the Reach M+. The M+ does not draw more than 1A by my meter, but it looks like it draws spikes of power at regular intervals, and maybe the cheap power supply can’t keep the voltage up for those power spikes. Adding a capacitor to the line would probably help, but I just used the cheap USB adapter with oversized amp rating (2A or 3A).