LoraMAC demo not working

[johnmcdnz]

I've received new Lopy units, and upgraded to latest version, details as:
(sysname='LoPy', nodename='LoPy', release='1.7.8.b1', version='v1.8.6-724-g2b9ed601 on 2017-07-28', machine='LoPy with ESP32', lorawan='1.0.0')

I've tried the basic LoraMAC sample and am not receiving any data between the pair of units.
(wifi is working fine)

I noticed an old support message, that mentions similar error.
https://forum.pycom.io/topic/770/lora-receiving-only-b

Is this bug still existing?

This is a pain as I'm doing a workshop demo later this week and wanted to use the units for a hands on demo.

[jcaron]

@johnmcdnz Just to be sure, you have connected the antenna to the correct port (the one next to the LED and reset button)?

[johnmcdnz]

@jcaron Yes. I already have two working Lopy from earlier delivery (on different os version) that are working fine.

[bucknall]

@johnmcdnz Could you please give a snippet of your code? I'll have a look at this now.

Thanks!

[johnmcdnz]

@bucknall Thanks Alex....
This code runs on both units, and each just prints b' ' repeatedly.

from network import LoRa
import socket
import time

#lora = LoRa(mode=LoRa.LORA, frequency=925000000, sf=7)
lora = LoRa(mode=LoRa.LORA, frequency=925000000, power_mode=LoRa.ALWAYS_ON, tx_power=5, bandwidth=LoRa.BW_250KHZ, sf=7, preamble=8, coding_rate=LoRa.CODING_4_5, tx_iq=False, rx_iq=False)

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

while True:
# send some data
s.setblocking(True)
s.send('Hello')
print('hello send')

# get any data received...
s.setblocking(False)
data = s.recv(64)
print(data)

# wait a random amount of time
time.sleep(machine.rng() & 0x0F)

[johnmcdnz]

Sleep on it....

Alex, and anyone else: I came home this evening to have another crack at this problem. Turned my PC on (Lopy powered from the USB ports). Suddenly I see the 'hello' message!!!!

What can I say?

I have each unit on opposite sides of the PC, about 50cm apart. So we can suspect some local RF interference probably.

Now I can get my workshop demo ready.

[bucknall]

@johnmcdnz Great to hear! Sometimes it's worth changing external variables for things like RF. I know I've previously had issues with some antennas as well.

[johnmcdnz]

@bucknall
Had a couple of hours on it and have all 5 units working. I'm not sure I fully understand the issue, but this is what I noticed:

I have a wifi router connected to my laptop, that I'm using as a separate AP for the Lopy. If I disconnect the ethernet from the Laptop, this may remove the problem.
So, I've wondering if there is RF EMC interference in the cables between the router/laptop/lopy.
Also if I then reboot the Lopy the problem disappears.