FiPy LTE Not Initialized

[ssummers]

I have a FiPy that is connecting to the lte network but after a few hours of running i will get the following error.

[ 71998.935] MQTT published packets: 1
[ 71999.936] MQTT published packets: 1
[ 72000.937] MQTT published packets: 1
[ 72001.934] MQTT published packets: 1
[ 72002.935] MQTT published packets: 1
[ 72003.937] MQTT published packets: 1
[ 72004.933] MQTT published packets: 1
[ 72005.935] MQTT published packets: 1
[ 72006.936] MQTT published packets: 1
[ 73074.841] MQTT publish error: [Errno 113] ECONNABORTED
[ 73074.851] MQTT published packets: 1
[ 73089.333] MQTT connect error: [Errno 202] EAI_FAIL
[ 73089.342] LTE disconnecting...
[ 73112.411] LTE disconnected
Traceback (most recent call last):
File "main.py", line 1, in <module>
File "lrio.py", line 152, in <module>
File "lrio.py", line 152, in <module>
File "/flash/lib/lte.py", line 58, in reconnect
File "/flash/lib/lte.py", line 82, in _start
File "/flash/lib/lte.py", line 26, in _attach
OSError: LTE modem not initialized
Pycom MicroPython 1.20.2.r0 [v1.11-783192e] on 2020-08-06; FiPy with ESP32

My program is publishing data to our mqtt broker and then I get an aborted error from the broker so I close the mqtt connection and try to reconnect leaving the lte connection alone. When I call the mqtt connect, I get error 202. So I am assuming this is a network error. I then disconnect the lte modem and then reconnect but I get the error "LTE modem not initialized". Is this caused by resetting the modem during the deinit? Here is my lte code.

from network import LTE
import utime
import _thread
from debug import log
from constants import const

class lte:

    def __init__(self, reset=False):
        self.lte = LTE(carrier=const.LTE_CARRIER, cid=const.LTE_CID)
        self.connected = False
        self.reset = reset

        if self.reset:
            self.lte.reset()

        self.lte.lte_callback(LTE.EVENT_COVERAGE_LOSS, self._lte_cb)

        # _thread.start_new_thread(self._start, ())

    def _lte_cb(self, lte):
        log('LTE coverage lost')
        self.reconnect()

    def _attach(self):
        if not self.lte.isattached():
            try:
                self.lte.attach(band=const.LTE_BAND, cid=const.LTE_CID, apn=const.LTE_APN)
                log('LTE attaching...')
                while not self.lte.isattached():
                    utime.sleep_ms(250)
                log('LTE attached')
            except Exception as ex:
                log('LTE attach error: {}', ex)

    def _connect(self):
        if self.lte.isattached():
            try:
                self.lte.connect()
                log('LTE connecting...')
                while not self.isconnected():
                    utime.sleep_ms(250)
                log('LTE connected')
                return True
            except Exception as ex:
                log('LTE connect error: {}', ex)
        else:
            log('LTE cannot connect because it is not attached')
            return False

    def reconnect(self):
        if self.connected:
            log('LTE disconnecting...')
            self.lte.deinit(reset=self.reset)
            log('LTE disconnected')
            self.connected = False
            # _thread.start_new_thread(self._start, ())
            self._start()

    def isconnected(self):
        return self.lte.isconnected()

    def rssi(self):
        if self.isconnected():
            self.lte.pppsuspend()
        rssi = int(self.lte.send_at_cmd('AT+CSQ').split('\r\n')[1].split(' ')[1].split(',')[0])
        if self.isconnected():
            self.lte.pppresume()
        if rssi is 99:
            return rssi
        else:
            return (rssi * 2) - 113

    def send_at_cmd_pretty(self, cmd):
        response = self.lte.send_at_cmd(cmd).split('\r\n')
        for line in response:
            log('{}', line)

    def _start(self):
        while not self.connected:
            # self.lte.init(carrier=const.LTE_CARRIER)
            self._attach()
            if self._connect():
                self.connected = True
            else:
                self.lte.deinit(reset=self.reset)
                utime.sleep(30)

[ssummers]

@kjm Thank you for the response. You are right about the deint. I made a test program that would go through the steps to connect over lte, then get the address of a server to verify connection, and then call my reconnect logic. I could duplicate the same error so I added the init function call just before the attach and now it works.

[kjm]

@ssummers In answer to your question, it's not the reset causing the 'not initialised' error it's the denit itself, you have disposed of the lte so you need to make a new one, lte=LTE() Re network disconnections, I've never had any luck with getting the sequans to reconnect on an existing attachment.

My experience in marginal RF environments is that the modem actually looses attachment but doesn't know it, lte.isattached() and lte.isconnected() are both true but trying lte.disconnect() throws an OSError. I call this ZombiModem mode & the the only fix is to reset the modem & setup a new lte/attachment/connection.

[Gijs]

Hi,
We've seen more examples of the LTE connection dropping after some period. While this is not desirable, it is inevitable, as the RF link is highly variable etc.) It should of course be recoverabl. One thing to do is indeed the lte.reset(), you can add parameter debug=True to get more information about the communication between the modem and microcontroller. It should also be possible to hard reset the modem in the last case you mentioned, altough at the moment Im not exactly sure how without hardware modifications

Best,
Gijs

[ssummers]

I forgot to add the following:

FiPy with firmware version 1.20.2.r0
Your modem is in application mode. Here is the current version:
UE5.0.0.0d
LR5.1.1.0-41065