LoPy4 LoRa Data Corruption

[ssmith]

I'm trying to get raw lora data transmission going on the LoPy4's. I've been running the original LoPy's for a year with no issues but the LoPy4's seem to get scrambled data. I created a small test program to verify. Any ideas what could cause this? I'm running the same code on 2 units.

import socket
import machine
import time

# initialize LoRa in LORA mode
# more params can also be given, like frequency, tx power and spreading factor
lora = LoRa(mode=LoRa.LORA)
lora.init(mode=LoRa.LORA, frequency=918000000, power_mode=LoRa.ALWAYS_ON, tx_power=20, bandwidth=LoRa.BW_125KHZ, sf=9,
              preamble=8, coding_rate=LoRa.CODING_4_8, tx_iq=False, rx_iq=False)
# create a raw LoRa socket
s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
# send some data
s.setblocking(True)
s.send('Hello From COM7')

while True:

    # get any data received...
    s.setblocking(False)
    data = s.recv(64)
    if data:
      print(data)
      time.sleep(0.5)
      s.setblocking(True)
      s.send('Hello From COM7')

    # wait a random amount of time
  #  time.sleep(1)

Here's the console output.

b'Hello From \xc7OM7'
b'Hello Erom \xc7OM7'
b'Hello From \xc5OM7'
b'Hello From \xc5OM7'
b'Hello From\x10\xc6OM7'
b'Hello From COM7'

[seb]

@ssmith

Hi,

You can find all the specs for the LoRa transceiver we're using on these modules here:

LoPy: https://www.semtech.com/uploads/documents/sx1272.pdf

LoPy4: https://www.semtech.com/uploads/documents/sx1276.pdf

[ssmith]

This appears to be a receiver saturation issue. At what point does the LoRa receiver saturate? my rssi is at -25 on both devices. If I change the sf to 7 then I don't get errors.

[ssmith]

Yes, both running 1.15. I also see it on ones running 1.13. If I run a lopy4 and a lopy I don't get any data through.

[seb]

Hi,

Are both LoPy4's running on the latest firmware? We released a new update yesterday. Can you try updating both and let me know if the issue persists?