Connecting LORA-WAN to LoPy (Please Help)

End Devices (Nodes) Pycom
1

Hi,

We are having trouble connecting our node (LoPy) to the gateway (Raspberry Pi + Dragino Hat). Our gateway is connected and being seen on the things network, but our node is never seen (but there is a green indicator).

We were able to send a message to the gateway ONE time and our node was finally being seen, but we’re having difficulty duplicating how we were able to get a message.

We set up our node and gateway exactly in the links below (we are located in the US):

GateWay (Dragino Hat and raspberry pi 3):

Node (LoPy 1):

Any help is appreciated.

3

Do you have the code you used on your LoPy? It sounds like the single channel setting hasn’t been setup correctly.

4

The Raspberry Pi single channel code - https://github.com/tftelkamp/single_chan_pkt_fwd - is no longer supported for The Things Network.

That configuration definitely does not support OTAA because it doesn’t support downlinks.

5 
from network import LoRa 
import struct 
import binascii 
import socket 
freq = 902300000

# Initialize LoRa in LORAWAN mode. 
lora = LoRa(mode=LoRa.LORAWAN)

#Setup the single channel for connection to the gateway 
for channel in range(0, 72): 
   lora.remove_channel(channel) 
for chan in range(0, 8): 
   lora.add_channel(chan,  frequency=freq,  dr_min=0,  dr_max=3) 

#Device Address 
dev_addr = struct.unpack(">l", binascii.unhexlify('2602122D'))[0] 
#Network Session Key 
nwk_swkey = binascii.unhexlify('XXXX') 
#App Session Key 
app_swkey = binascii.unhexlify('XXXX') 

lora.join(activation=LoRa.ABP, auth=(dev_addr, nwk_swkey, app_swkey)) 

# create a LoRa socket 
s = socket.socket(socket.AF_LORA, socket.SOCK_RAW) 

# set the LoRaWAN data rate 
s.setsockopt(socket.SOL_LORA, socket.SO_DR, 3) 

# make the socket non-blocking 
s.setblocking(False)

Taken straight from the “LoPy to Single Channel Gateway” tutorial.

6

Just a tip, I’d remove the nwk and app key from the post as they’re meant to be kept secret :wink:

Where do you get the freq being 902300000 from? From what I can see US Single channel gateways should be on 903900000

1 Like
7

Honestly, that was just straight from the code as well. Can you share where you read that frequency should be 903900000? I will try setting this within the code, but just wanted to understand/read up more on this.

And thanks for the tip, went back and removed the keys.

8

It was in LoPy’s documentation for single channel gateways.

It’ll depend on the frequency of your raspberry pi gateway setting. Do you have a screenshot of the log from it?

9

I was using a Pi and a Dragino as my first gateway and found that only certain packets got through. However, the pi gateway showed a log message when it received a packet and forwarded it to the Lorawan network.

I think you can set the Pycom to use US frequencies by specifying the region. .e.g mine was specified as follows:
lora = LoRa(mode=LoRa.LORAWAN, region=LoRa.EU868)

I don’t know if you have only sent through part of your program, but mine concludes with …

# make the socket blocking
# (waits for the data to be sent and for the 2 receive windows to expire)
s.setblocking(True)
 
# send some data
s.send(bytes([0x01, 0x02, 0x03]))

It’s only when the socket send method is called, does anything actually happen on the network.