GPy with Hologram.io SIM

[jmarcelino]

@tlanier
Were you using the code you posted below? I didn't notice you had changed the code you to calling lte.attach() again. Have you been doing the other tests with this?

For setups like Hologram where you do a custom init you need to remove lte.attach() and use AT+CEREG=2 and AT+CFUN=1 manually.

As you already have those in the code you need to remove lte.attach() otherwise it will cause problems.

[tlanier]

@tlanier
I took the Gpy 50 miles down Interstate 85 through West Point, GA and Opelika, AL. The device never attached to a cell tower during the entire trip.

[tlanier]

@jmarcelino

Thanks, I've updated the code.

[jmarcelino]

@tlanier

I'm afraid the manual is written by Sequans (who make the modem) and is more of a general guide for all possible implementations.

The LED on the FiPy/GPy is only connected to the ESP32/MicroPython and not to the modem. The SQNLED command will have no effect.

The correct way to check for correctly registration is via AT commands and specifically the status check AT+CEREG? Valid registration stats are 2,1 or 2,5 (for MVNOs)

[tlanier]

@jmarcelino
Below is the code I'm going to use in the GPy plugged into my car USB port. The LED will show me the attach/connection state. This evening I plan to drive to multiple locations to see if I can make it work.

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

# send AT command to modem and display response
def at(cmd):
    print("modem command: {}".format(cmd))
    response = lte.send_at_cmd(cmd).split('\r\n')
    for line in response:
        print(line)

#####################################################################
print("CAT M1 Test - V0.2")

print("disable MicroPython contorl of LED")
pycom.heartbeat(False)
pycom.rgbled(0xFFFFFF)  # White

print("instantiate LTE object")
lte = LTE(carrier="verizon")
print("delay 4 secs")
time.sleep(4.0)

if lte.isattached():
    print("LTE was already attached, disconnecting...")
    lte.disconnect()
    lte.detach()
    print("resetting modem...")
    lte.reset()
    print("delay 5 secs")
    time.sleep(5.0)

# using hologram SIM
at('AT+CGDCONT=1,"IP","hologram"')

# enable network registration and location information unsolicited result code
# +CEREG: <stat>[,[<tac>],[<ci>],[<AcT>]]
at('AT+CEREG=2')

print("full functionality level")
at('AT+CFUN=1')
time.sleep(1.0)

print("attempt to attach cell modem to base station...")
lte.attach()
i = 0
while not lte.isattached():
    i = i + 1
    print("not attached: {} secs".format(i))

    if (i % 2 == 0):
        pycom.rgbled(0xFF0000)  # Red
    else:
        pycom.rgbled(0x000000)  # Off

    # get EPS Network Registration Status:
    # 0 - not registered
    # 1 - registered, home network
    # 2 - not registered, but searching...
    # 3 - registration denied
    # 4 - unknown (out of E-UTRAN coverage)
    # 5 - registered, roaming
    at('AT+CEREG?')
    time.sleep(1)

print("connect: start a data session and obtain an IP address")
lte.connect()
i = 0
while not lte.isconnected():
    i = i + 1
    print("not connected: {}".format(i))

    if (i % 2 == 0):
        pycom.rgbled(0x00FF00)  # Green
    else:
        pycom.rgbled(0x000000)  # Off

    time.sleep(1.0)

pycom.rgbled(0x0000FF)  # Blue

s = socket.socket()
s = ssl.wrap_socket(s)
s.connect(socket.getaddrinfo('www.google.com', 443)[0][-1])
s.send(b"GET / HTTP/1.0\r\n\r\n")
print(s.recv(4096))
s.close()

lte.disconnect()
lte.dettach()

# end of test
print("end of test")
pycom.rgbled(0xFFFF00)    # Yellow

while True:
    pass

[tlanier]

@jmarcelino
Sorry, my mistake. I was reading the description of the AT+SQNLED=<mode> command (see below) and thought it was describing the purpose of the AT+CFUN command instead of describing how the LED behaved with the different CFUN values.

From manual:

This command configures the control of light of a connected LED. The mode
setting is persistent after reboot.
The LED is turned on only when AT+CFUN=1 or 4. It is turned off when
AT+CFUN=0.
LED is steadily turned on when the ME is registered to the network and either
awake or in power saving state. LED flashes when the ME is registered to the
network and either awake or in power saving state. In this mode, the duration
of flashing means various states, listed below:
• AT+CFUN=0 or 4. The ME is stopped or in Airplane mode. The LED is
permanently turned off.
• AT+CFUN=1. LTE PS data transfer. The LED is permanently turned on.
• AT+CFUN=1. The ME is registered to a network, No call, no data transfer
(in RRC Idle). The LED blinks (typically 1280 ms on, 3840 ms off).
• AT+CFUN=1. Limited Network Service (no SIM, no PIN, network search).
The LED blinks (typically 500 ms on, 500 ms off).
• AT+CFUN=1. The ME is in deep SLEEP (eDRX or PSM). The LED is permanently
turned off.

[nathanh]

@jmarcelino said in GPy with Hologram.io SIM:

For Telstra/Australia you need to set the correct EARFCN (with 'AT!="addscanfreq band=28 dl-earfcn=9410"'). For the US the modem knows the Verizon network already so you don't need to.

Which is what we are using and documented in the several Telstra posts on the forum and are still waiting on you/Pycom to refer back from meeting with Telstra as @daniel indicated on this thread (https://forum.pycom.io/topic/2769/telstra-lte-cat-m-working-on-fipy-just/21)

My point was that while the report of 2,4 from CEREG typically indicates no coverage, the actual reason according to the documentation is unknown error and even if it was lack of coverage it did not make sense since I could also get connectivity randomly in the same location with the same device, and the signal strength reporting as good/excellent when it did connect. Which in my mind could potentially indicate other issues with how the modem itself communicates on different networks.

[jmarcelino]

@nathanh said in GPy with Hologram.io SIM:

For what it is worth and not trying to take this off the current topic/carrier. But from my attempts at trying to use my FiPy on Telstra where I am under full coverage, I also get the 2,4 result from CEREG but it will also sometimes connect (for a time before it crashes).

For Telstra/Australia you need to set the correct EARFCN (with 'AT!="addscanfreq band=28 dl-earfcn=9410"'). For the US the modem knows the Verizon network already so you don't need to.

@tlanier said in GPy with Hologram.io SIM:

One interesting piece of information is that the AT+CFUN=0 or AT_CFUN=1 commands do not return an "OK" response from the modem. The commands configure the control of the LED according to the manual.

I'm not sure which manual you're following but on the one we provide CFUN is definitely used to enable/disable the radio: see "2.4 Set Phone Functionality: +CFUN:".

[tlanier]

@jmarcelino

One interesting piece of information is that the AT+CFUN=0 or AT_CFUN=1 commands do not return an "OK" response from the modem. The commands configure the control of the LED according to the manual.

[tlanier]

@tealbrains said in GPy with Hologram.io SIM:

Thanks for the input.

I think the trick to get the code to be properly formatted is to surround it with with three back-ticks (key to left of the "1" key). See a better description at (https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet) under the section titled "Code and Syntax Highlighting".

Looking at your code I'm not sure what I should use for the send_at_cmd_pretty('AT!="addscanfreq band=28 dl-earfcn=9410"') command. That looks like a region specific setting.

[tealbrains]

@nathanh I got it to connect to Telstra thanks to @micksta and his other post. But it breaks after that. I would suggest to @tlanier to configure the LTE with some commands, otherwise it does not know what to do. See the code below (modification of @micksta 's):

[sorry about the format, the "Insert Code Block" button does not work for me] Edit: thanks @tlanier I fixed it.

#import os
#os.mkfs('/flash')

import time
import socket
import gc
from network import LTE
import ssl

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


print('Starting LTE...')
lte = LTE() # instantiate LTE object
print('LTE instantiated')
time.sleep(4.0)

if lte.isattached():
    #important, otherwise it can get stuck
    lte.disconnect()
    lte.dettach()
    print("LTE was still attached. Disconnecting it.")


lte.reset()
print ('LTE has been reset')
time.sleep(5.0)

send_at_cmd_pretty('AT+CGDCONT=1,"IP","telstra.internet"')
print ('APN set') 
time.sleep(1.0)

send_at_cmd_pretty('AT!="addscanfreq band=28 dl-earfcn=9410"') # lte frequency band - from forum
print ('Chose frequency band') 
time.sleep(1.0)

send_at_cmd_pretty('AT+CFUN=1') # Set the full functionality mode with a complete software reset
print ('Writing configuration...') 
time.sleep(1.0)

print('LTE initialised')

#show wireless parameters
send_at_cmd_pretty('AT!="showphy"')     # get the PHY status
send_at_cmd_pretty('AT!="fsm"')         # get the System FSM

print("Attaching...")
lte.attach() # attach the cellular modem to a base station
while not lte.isattached():
    time.sleep(0.25)
print ('Attached!') 

print("Connecting...")
lte.connect() # start a data session and obtain an IP address
while not lte.isconnected():
    time.sleep(0.25) 
print ('Connected!') 

#LTE Connection established
print("LTE is working")

s = socket.socket()
addr_info = socket.getaddrinfo('httpbin.org', 80)
addr = addr_info[0][-1]

print(addr)
s.connect(addr)
print("socket is ready")

s.send(b"GET / HTTP/1.0\r\n\r\n")
print(b"GET / HTTP/1.0\r\n\r\n")
print("Sent GET request")

print(s.recv(4096))
print("Received something")

lte.disconnect()
lte.dettach()
s.close()
gc.collect()

[nathanh]

@jmarcelino said in GPy with Hologram.io SIM:

However you got +CEREG: 2,4 which means the modem did not find a network to connect, this suggests to me there is coverage issue and it would be interesting to know if you get a different result elsewhere.

For what it is worth and not trying to take this off the current topic/carrier. But from my attempts at trying to use my FiPy on Telstra where I am under full coverage, I also get the 2,4 result from CEREG but it will also sometimes connect (for a time before it crashes). I have left my modem in the same spot all day and it appears totally random if I can connect or not. Even when I connect, I will force a disconnect or reboot my FiPy and try and reconnect and next attempt will typically result with a 2,4 from CEREG even though less than 20 seconds earlier I was connected and sending JSON data off to my server.

[jmarcelino]

@tlanier
I understand you concern but there is no incompatibility with SIMs or hardware issues. The modem has been certified by and works correctly with Verizon and for them (with a Cat M1 SIM) you can just do

lte = LTE(carrier=“verizon”)

and everything is setup correctly. For other configurations including MVNOs like Hologram we still need to do some manual tuning on the current modem firmware. This will no doubt improve as certification and firmware work continues.

The modem firmware is separate from the MicroPython code. Currently the only way to update the modem firmware is loading from SD card using this tool: https://github.com/pycom/pycom-libraries/tree/master/lib/sqnsupgrade . This will also be much simplified in the near future.

Regarding your specific case Chris was seeing +CEREG: 2,5 which means the modem actually found and registered on the network, the issue he had was with connect (establishing the PPP session).

However you got +CEREG: 2,4 which means the modem did not find a network to connect, this suggests to me there is coverage issue and it would be interesting to know if you get a different result elsewhere.

[tlanier]

@jmarcelino

Have any conclusions been reached about the connection problem?

Possibilities:

• Coverage problem?
  I've tried in multiple locations in my town of 35,000. We've contacted Verizon and they indicate that CAT-M1 coverage is everywhere that 4G LTE CAT-1 coverage is at. Also, since Chris is in Chicago and is also having trouble leads me to think that coverage is not the problem. Tonight I will take the device to a larger town to see if I have the same connection problem.

• SIM card issue?
  Is it possible that the Hologram SIM card is somehow incompatible with the GPy? Would some other SIM card from another vendor possibly work?

• GPy firmware issue?
  Is it possible that the GPy has a firmware issue that can be corrected? When we update the firmware to the GPy does that update both the MicroPython firmware and the cell modem firmware also?

• GPy hardware issue?
  Is it possible that the GPy isn't compatible with current Verizon CAT-M1 service?

Thanks for any insights you may have concerning the problem.

[jmarcelino]

Thank you so much @chrisgammell That is really crucial "field" information for us!

From a quick look it seems AT+CGDATA is timing out but maybe we just don't give it enough time to complete. I'll check with our LTE team.

Thanks again

[ChrisGammell]

Ah, and re-reading, I saw I should check on "lte.isattached()" which in my case returns true:

So is the lte.connect() function the problem here Or are there other hints of what I should be trying?

[ChrisGammell]

@jmarcelino ah, that makes sense. Sorry, I should have explained I tried doing the attach command again after I noted that the lte.connect() function did not function properly. It still throws an error. Here is the entirety of the code I'm using:

import socket
import ssl
import time
from network import LTE

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

lte = LTE()         # instantiate the LTE object

pretty('AT+CGDCONT=1,"IP","hologram"')

pretty('AT+CFUN=0')
pretty('AT+SQNCTM="verizon"')

pretty('AT+CGDCONT=1,"IP","hologram"')
pretty('AT+CEREG=2')
pretty('AT+CFUN=1')

pretty('AT!="showinit"')

while not lte.isattached():
    time.sleep(1)
    pretty('AT!="showphy"')
    pretty('AT!="fsm"')
    pretty('AT+CEREG?')


lte.connect()
while not lte.isconnected():
    time.sleep(1)
print("Connected!")

And I still get the following response:

I believe the connect function isn't working because the modem is still not attached.

[jmarcelino]

Hi @chrisgammell ,

Can you try again without calling lte.attach() please?

I'm trying to avoid any wrong/missing assumptions lte.attach() is doing so the code I posted should replace that entire step, if you call lte.attach() again after that you'll effectively undo the parameters we set via custom AT commands and ask the modem to reattach with the problem settings.

If you see "+CEREG: 2,5,... this means the modem is attached and lte.isattached() should return true (even if you didn't use lte.attach()...)

It should then be ready to connect (start the PPP session) via lte.connect()

Being certified by Verizon means we must include a specific configuration for them inside the modem - it's what CID=3 does - which sets everything correctly for them including APN, bands and a lot of other stuff they require... this was done in tight collaboration with them by the modem manufacturer so we don't need these manual configuration steps.

[ChrisGammell]

@jmarcelino no, it still doesn't attach, unfortunately

>>> lte.attach()
>>> lte.connect()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: modem not attached

Don't want to usurp the other issues that @tlanier is having, but curious to understand why the other steps are necessary. Were those necessary with a Verizon SIM?

[tlanier]

@tlanier

Do you know if Verizon publishes a coverage map for CAT-M1?

Maybe I should try taking the device to a larger city (Newnan or Atlanta) to see if it works there.

This is what it displays at the start of the test:

CAT M1 Test - V0.1

OK

OK

OK

OK

OK

-- Scan options -------------------------------------------
| . Init Stored info use : true
| . Init MRU freq use : true
| . Init REG freq use : false
| . Init FastScan use : true
| . Init iterative band scan : false
| . Init scan batch of freq : false
| . Init hybrid 1 mode : false
| . Init optim SIB rx : true
| . Forced freq : false

. MRU cell use : true

-- Scan Command config ----------------------------------------------------
| id | type | object |

| 1 | BAND | (id:1) 4,13 |
| 2 | DELAY | 5000 msec |
| 3 | LOOP | jump to cmd:1, dur:5000ms |

OK