LTE driver appears to be stopped?

Recurracy

Hello everyone,

I'm currently trying to connect to an LTE CAT M1 network.
However, I'm seeing some things that I think aren't quite correct, and I'm not sure what to do.

Here is the code I'm using to attempt to connect:

from network import LTE
import pycom
import machine
import time

lte = LTE()

def pretty(cmd):
    print(cmd)
    response = lte.send_at_cmd(cmd).split('\r\n')
    for line in response:
        if line != '':
            print(line)

print("Test")
pycom.heartbeat(False)
pycom.rgbled(0xFF0000)

if not lte.isattached():
    lte.attach()
    while (not lte.isattached()):
        print("Attaching to LTE... ")
        pycom.rgbled(0xFF0000)
        pretty('AT!="showphy"')
        time.sleep(5)
        pycom.rgbled(0x000000)
        pretty('AT!="fsm"')
        time.sleep(5)

if not lte.isconnected():
    lte.connect()
    while not (lte.isconnected()):
        print("Connecting...")
        time.sleep(1)

pycom.rgbled(0x00FF00)
time.sleep(0.5)
pycom.rgbled(0x000000)

It doesn't even get past the attaching phase.
This is the output of the FSM AT command:

SYSTEM FSM
==========
    +--------------------------+--------------------+
    |            FSM           |        STATE       |
    +--------------------------+--------------------+
    | RRC TOP FSM              |STOPPED             |
    | RRC SEARCH FSM           |NULL                |
    | RRC ACTIVE FSM           |NULL                |
    | PMM PLMN FSM             |NULL                |
    | EMM MAIN FSM             |NULL                |
    | EMM AUTH FSM             |NULL                |
    | EMM CONN FSM             |NULL                |
    | EMM TAU FSM              |NULL                |
    | EMM TEST FSM             |NULL                |
    | ESM BEARER FSM           |BEARER_NULL         |
    | SMS MT FSM               |IDLE                |
    | SMS MO FSM               |IDLE                |
    | HP MAIN FSM              |NULL                |
    | HP USIM FSM              |NULL                |
    | HP SMS MO FSM            |IDLE                |
    | HP SMS MT FSM            |IDLE                |
    | HP CAT FSM               |NULL                |
    +--------------------------+--------------------+

Here is the output of the 'showphy' AT command:

DL SYNCHRO STATISTICS
=====================
    Synchro state                         : OFF
    PPU SIB1 ACQ watchdog                 : 0
    Frequency Hypothesis RF  (Hz)         : 0
    RSRP (dBm)                            : 0.00
    RSRQ  (dB)                            : 0.00
    Channel estimation state (Cell-spec.) : LOW CINR
    Channel estimation state (UE-spec.)   : LOW CINR
    Channel estimation state (MBSFN)      : LOW CINR
    Channel estimation CINR               : 0.00
    Channel length                        : SHORT
  AGC
    AGC RX gain (dB)                      : 0.00
    RX PSD BO (dBFs)                      : 0.00
    RX PSD (dBm)                          : 0.00
    Noise level RS (dBm)                  : 0.00
    Digital gain (dB)                     : 0.00
    CINR RS (dB)                          : 0.00
  NARROWBANDS
    Last DL NB                            : 0
    Last UL NB                            : 0
  AFC
    Frequency offset RF  (Hz)             : 0
    Frequency offset BB  (Hz)             : 0
  PBCH
    MIB received quantity                 : 0
    MIB timeout quantity                  : 0
OK

I should note I have entered AT commands in the past before taking a simpler approach, such as "AT!=clearscanconfig". Is this command persistant after resetting the device?

I've also updated the LTE driver as described in https://docs.pycom.io/tutorials/lte/firmware.html

rskoniec

@recurracy If you mean Expansion board - yes, RTS and CTS jumpers must be removed for modem communication.

https://docs.pycom.io/gettingstarted/connection/fipy.html
When using the expansion board with a FiPy, you will need to remove the CTS and RTS jumpers as these interfere with communication with the cellular modem.

Recurracy

I managed to get it working. Thank you for your responses, @tlanier.

Is it true the RTS and CTS jumpers on the Pymakr board can make a difference in the modem functioning? I had connected them before, a colleague suggested taking them off.

Here is the initialization code:

print("init lte")
lte.init()
print("reset lte")
lte.reset()
pretty('AT^RESET')
time.sleep(5)
pretty('AT+CFUN=0')
pretty('AT!="clearscanconfig"')
pretty('AT!="addscanfreq band=20 dl-earfcn=6400"')
pretty('AT+CGDCONT=1, "IP", "ltem.internet.m2m"')
pretty('AT+CFUN=1')
pretty('AT+CEREG?')
pretty('AT+COPS=?')

tlanier

@recurracy

Have you added an APN to the attach method call?

apnx = "10569.mcs" # apn based on SIM card used
lte.attach(apn=apnx)

Recurracy

Sadly, that didn't seem to change anything. I'm not sure why, but the synchro state continues to be OFF, and all other values remain 0, as if nothing has been initialized:

DL SYNCHRO STATISTICS
=====================
    Synchro state                         : OFF
    PPU SIB1 ACQ watchdog                 : 0
    Frequency Hypothesis RF  (Hz)         : 0
    RSRP (dBm)                            : 0.00
    RSRQ  (dB)                            : 0.00
    Channel estimation state (Cell-spec.) : LOW CINR
    Channel estimation state (UE-spec.)   : LOW CINR
    Channel estimation state (MBSFN)      : LOW CINR
    Channel estimation CINR               : 0.00
    Channel length                        : SHORT
  AGC
    AGC RX gain (dB)                      : 0.00
    RX PSD BO (dBFs)                      : 0.00
    RX PSD (dBm)                          : 0.00
    Noise level RS (dBm)                  : 0.00
    Digital gain (dB)                     : 0.00
    CINR RS (dB)                          : 0.00
  NARROWBANDS
    Last DL NB                            : 0
    Last UL NB                            : 0
  AFC
    Frequency offset RF  (Hz)             : 0
    Frequency offset BB  (Hz)             : 0
  PBCH
    MIB received quantity                 : 0
    MIB timeout quantity                  : 0

OK

Furthermore, 'AT+COPS=?' returns an ERROR. Which I find weird considering that I did upgrade the modem firmware. I'm not sure what is going on here.

tlanier

This example may help.

import pycom
import socket
import ssl
import sys
import time
from network import LTE
from utime import sleep_ms

BLACK = 0x000000
WHITE = 0xFFFFFF
RED = 0xFF0000
GREEN = 0x00FF00
BLUE = 0x0000FF
YELLOW = 0xFFFF00

lte = None

# send AT command to modem and return response as list
def at(cmd):
    global lte
    print("modem command: {}".format(cmd))
    r = lte.send_at_cmd(cmd).split('\r\n')
    r = list(filter(None, r))
    print("response={}".format(r))
    return r

# blink LED
def blink(rgb, n):
    for i in range(n):
        pycom.rgbled(rgb)
        time.sleep(0.25)
        pycom.rgbled(BLACK)
        time.sleep(0.1)

# run test
def run():
    global lte

    print("GPy CAT M1 Test - V0.6 - 2/26/19")

    try:
        print("disable MicroPython control of LED")
        pycom.heartbeat(False)
        pycom.rgbled(WHITE)

        print("instantiate LTE object")
        lte = LTE()

        print("reset modem...")
        lte.reset()

        # resolves issue of iccid() not working after reset()
        LTE.reconnect_uart()

        lte.init()
        sleep_ms(1500)      # 750 works

        iccid = lte.iccid()
        carrier = iccid[0:5]
        print("iccid = {0}".format(iccid))

        imei = lte.imei()
        print("imei = {0}".format(imei))

        apnx = "10569.mcs"   # apn based on SIM card used
        lte.attach(apn=apnx)

        while not lte.isattached():
            print("waiting for attach...")
            blink(RED, 1)

        print("connect: start a data session and obtain an IP address")
        lte.connect()

        while not lte.isconnected():
            print("waiting for connection...")
            blink(GREEN, 1)

        print("connected!!!")
        pycom.rgbled(BLUE)

        print("read first 16 bytes of www.google.com site")
        s = socket.socket()

        # must be called only if connecting to secure site
        s = ssl.wrap_socket(s)

        print("get www.google.com address")
        addr = socket.getaddrinfo('www.google.com', 443)
        print(addr)
        print("connect to {}".format(addr[0][-1]))
        s.connect(addr[0][-1])
        print("GET 16 bytes from google")
        s.send(b"GET / HTTP/1.0\r\n\r\n")
        print(s.recv(16))   # receive 16 bytes
        print("close socket")
        s.close()

        lte.disconnect()

        pycom.rgbled(BLACK)
        print("end of test")

    except Exception as ex:
        sys.print_exception(ex)

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