sending packets with Lopy (Lorawan)

[kots]

Hello!

I am trying to send values from my TMP 36 sensor through the lopy to my gateway. I am using the loriot network server.

The problem is that when i am trying to send the float data to my gateway i see this message :

The command i use is : s.send(datafromtmp).

I know that loriot shows any message i send in a hex form. I tried to use the binascii.hexlify method but it didnt work.

Any thoughts?

[jmarcelino]

@kots

Can you post the part of your code where you create the LoRa socket and join the network?

Alternatively follow the examples:

For OTAA: https://docs.pycom.io/chapter/tutorials/lopy/lorawan-otaa.html

Fot ABP: https://docs.pycom.io/chapter/tutorials/lopy/lorawan-abp.html

Finally make sure your LoPy firmware is up to date.

[kots]

@jmarcelino sure!
here is the code:
from network import LoRa
import time
import socket
import binascii
import struct
import machine
#import pycom

#pycom.heartbeat(False) #it turns the pycoms led off
#starting the procedure
print("start")

lora = LoRa(mode=LoRa.LORAWAN)

print("Dev EUI: ", binascii.hexlify(lora.mac()).upper().decode('utf-8'))

#ABP configuration

create an ABP authentication params

dev_addr = struct.unpack(">l", binascii.unhexlify(''))[0]
nwk_swkey = binascii.unhexlify('')
app_swkey = binascii.unhexlify('***********')

lora.add_channel(0,frequency=868100000,dr_min=0,dr_max=5)
lora.add_channel(1,frequency=868100000,dr_min=0,dr_max=5)
lora.add_channel(2,frequency=868100000,dr_min=0,dr_max=5)

#joining the network
lora.join(activation=LoRa.ABP, auth=(dev_addr, nwk_swkey, app_swkey))

wait until the network is joined

while not lora.has_joined():
pass
print("Joined LoRa Network")

#remove all the non-default channels

create a raw LoRa socket

s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)

s.setsockopt(socket.SOL_LORA, socket.SO_DR, 5)

s.setblocking(False)

adc=machine.ADC()
apin=adc.channel(pin='P16')
value=apin()
temp=((value*1100)/1024-500)/100

print("Sending Packet")
s.send(temp)

get the packet received (if any)

data = s.recv(64)
if data:
print(data)

[jmarcelino]

@kots
Thanks.

The problem is a socket only understand bytes, it doesn't know what do with integers or floating point values such as your temp.

You need to convert your temp into bytes ( and then back on the other side). The suggested way is using struct.pack() like this:

import struct
databytes = struct.pack('d', temp)
s.send(databytes)

this is for Python doubles (64 bits floating points), if you want C style 32 bit floats (losing precision but using less bytes) use f instead of d. See the struct docs for more options.

[kots]

@jmarcelino Thank you for your answer!