Using mikroe "LTE IoT Click" aka u-blox SARA-R410M-02B with native serial UART
Aleksander Morgado
aleksander at aleksander.es
Wed Apr 28 19:14:14 UTC 2021
Hey,
> > That looks promising, I'll see if I can register to the network if the
> > correct SIM cards arrive.
>
> I got the SIM cards now. Those are by German Telekom for business customers.
> (German FAQ here: [1])
>
> Recap: the modem is a u-blox SARA-R410M-02B, and it's connected through the
> serial UART only (NOT through USB), meaning only two pins, txd and rxd,
> classical uart, 115200 baud, /dev/ttyAT2.
>
> I got ModemManager (1.16.4) to recognize the modem and this works:
>
> mmcli -m 1 -e
> mmcli -m 1 --simple-connect='apn=iot.telekom.net'
> mmcli -m 1
>
Nice!
> The modem is shown in connected state with reasonable operator id 26201 and
> signal quality 80%. Debug log even shows an IP address (in 10.0.0.0/8), the
> same as listed in the web portal of Deutsche Telekom, which also confirms
> modem/sim are registered to the network. So far so good.
>
Yes.
> However there's no network device listed, `ip addr show` shows only ethernet
> and loopback.
>
Yes, the next step would be to run pppd over the TTY. What
ModemManager does is setting up the connection and putting the TTY in
data mode instead of command (AT) mode. Once it's in data mode, pppd
should take over.
> In the hope NetworkManager (1.30.4) would create that device for me, I tried
> to get a connection with NetworkManager like this:
>
> nmcli connection add type gsm
> nmcli connection modify gsm apn iot.telekom.net
>
That is fine, yes. NetworkManager can take care of the pppd setup once
MM connects the modem.
> And:
>
> root at DistroKit:~ nmcli -a con up gsm
> Error: Connection activation failed: The base network connection was
> interrupted
Ok, this may be because the modem was already in connected mode after
your manual --simple-connect?
Have you retried this but after fully power cycling the modem? If
you're using NetworkManager, you should *not* do --simple-connect
manually.
> Hint: use 'journalctl -xe NM_CONNECTION=0b5580ba-33f9-49f6-
> bd17-33c14d38bb97 + NM_DEVICE=ttyAT2' to get more details.
>
> I had NetworkManager monitor on a second console in parallel, which gave this:
>
> root at DistroKit:~ nmcli m
> ttyAT2: deactivating
> ttyAT2: disconnected
> ttyAT2: using connection 'gsm'
> ttyAT2: connecting (prepare)
> ttyAT2: unmanaged
> ttyAT2: device removed
>
> Now the interesting part, `journalctl -u ModemManager`:
>
> ```
> Apr 27 14:49:46 DistroKit systemd[1]: Starting ModemManager.service...
> Apr 27 14:49:47 DistroKit ModemManager[416]: <info> ModemManager (version
> 1.16.4) starting in system bus...
> Apr 27 14:49:47 DistroKit systemd[1]: Started ModemManager.service.
> Apr 27 14:49:50 DistroKit ModemManager[416]: <info> [base-manager] couldn't
> check support for device '/sys/devices/platform/ahb/ahb:apb/
> f8008000.ethernet': not supported by any plugin
> Apr 27 14:50:05 DistroKit ModemManager[416]: <info> [device /sys/devices/
> platform/ahb/ahb:apb/f8024000.serial/atmel_usart_serial.1.auto] creating modem
> with plugin 'generic' and '1' ports
> Apr 27 14:50:05 DistroKit ModemManager[416]: <warn> [plugin/generic] could
> not grab port ttyAT2: Cannot add port 'tty/ttyAT2', unhandled port type
> Apr 27 14:50:05 DistroKit ModemManager[416]: <warn> [base-manager] couldn't
> create modem for device '/sys/devices/platform/ahb/ahb:apb/f8024000.serial/
> atmel_usart_serial.1.auto': Failed to fi>
> Apr 27 14:50:10 DistroKit ModemManager[416]: <info> [base-manager] couldn't
> check support for device '/sys/devices/platform/ahb/ahb:apb/
> f8008000.ethernet': not supported by any plugin
> Apr 27 14:50:25 DistroKit ModemManager[416]: <info> [device /sys/devices/
> platform/ahb/ahb:apb/f8024000.serial/atmel_usart_serial.1.auto] creating modem
> with plugin 'generic' and '1' ports
> Apr 27 14:50:25 DistroKit ModemManager[416]: <warn> [plugin/generic] could
> not grab port ttyAT2: Cannot add port 'tty/ttyAT2', unhandled port type
> Apr 27 14:50:25 DistroKit ModemManager[416]: <warn> [base-manager] couldn't
> create modem for device '/sys/devices/platform/ahb/ahb:apb/f8024000.serial/
> atmel_usart_serial.1.auto': Failed to fi>
> Apr 27 14:50:50 DistroKit ModemManager[416]: <info> [base-manager] couldn't
> check support for device '/sys/devices/platform/ahb/ahb:apb/
> f8008000.ethernet': not supported by any plugin
> Apr 27 14:50:58 DistroKit ModemManager[416]: <info> [device /sys/devices/
> platform/ahb/ahb:apb/f8024000.serial/atmel_usart_serial.1.auto] creating modem
> with plugin 'u-blox' and '1' ports
> Apr 27 14:50:59 DistroKit ModemManager[416]: <info> [base-manager] modem for
> device '/sys/devices/platform/ahb/ahb:apb/f8024000.serial/atmel_usart_serial.
> 1.auto' successfully created
> Apr 27 14:50:59 DistroKit ModemManager[416]: <warn> [modem2] (u-blox)
> unexpected AcT value: 7
> Apr 27 14:50:59 DistroKit ModemManager[416]: <warn> [modem2] (u-blox)
> unexpected AcT value: 8
> Apr 27 14:50:59 DistroKit ModemManager[416]: <warn> [modem2] couldn't load
> supported modes: No combinations built from +URAT=? response
> Apr 27 14:50:59 DistroKit ModemManager[416]: <warn> [modem2] couldn't load
> unlock retries: Unknown error
> Apr 27 14:50:59 DistroKit ModemManager[416]: <warn> [modem2/sim0] couldn't
> load list of emergency numbers: uninitialized emergency numbers list
> Apr 27 14:50:59 DistroKit ModemManager[416]: <warn> [modem2] couldn't load
> list of own numbers: Invalid characters in dial string
> Apr 27 14:50:59 DistroKit ModemManager[416]: <warn> [modem2] couldn't load
> current bands: Unknown error
> Apr 27 14:50:59 DistroKit ModemManager[416]: <info> [modem2] state changed
> (unknown -> disabled)
> Apr 27 14:50:59 DistroKit ModemManager[416]: <info> [modem2] state changed
> (disabled -> enabling)
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] simple connect
> started...
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (4/8): wait to get fully enabled
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] 3GPP
> registration state changed (unknown -> idle)
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] state changed
> (enabling -> enabled)
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (5/8): register
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] 3GPP
> registration state changed (idle -> registering)
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] 3GPP
> registration state changed (registering -> roaming)
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] state changed
> (enabled -> registered)
> Apr 27 14:51:00 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (6/8): bearer
> Apr 27 14:51:01 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (7/8): connect
> Apr 27 14:51:01 DistroKit ModemManager[416]: <info> [modem2] state changed
> (registered -> connecting)
> Apr 27 14:51:01 DistroKit ModemManager[416]: <info> [modem2] state changed
> (connecting -> connected)
> Apr 27 14:51:01 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (8/8): all done
> Apr 27 14:51:06 DistroKit ModemManager[416]: <warn> [modem2] couldn't load
> network timezone from the current network
> Apr 27 14:51:12 DistroKit ModemManager[416]: <info> [base-manager] couldn't
> check support for device '/sys/devices/platform/ahb/ahb:apb/
> f8008000.ethernet': not supported by any plugin
> Apr 27 14:55:36 DistroKit ModemManager[416]: <info> [modem2] state changed
> (connected -> disconnecting)
Is this log from your manual test in which you connected with
--simple-connect and then you tried with NetworkManager?
> Apr 27 14:55:45 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 2 consecutive times
> Apr 27 14:55:48 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 3 consecutive times
> Apr 27 14:55:51 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 4 consecutive times
> Apr 27 14:55:54 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 5 consecutive times
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2] state changed
> (disconnecting -> registered)
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2/bearer0]
> connection #1 finished: duration 302s, tx: 0 bytes, rx :0 bytes
> Apr 27 14:56:04 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 6 consecutive times
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2] simple connect
> started...
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (4/8): wait to get fully enabled
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (5/8): register
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (6/8): bearer
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (7/8): connect
> Apr 27 14:56:04 DistroKit ModemManager[416]: <info> [modem2] state changed
> (registered -> connecting)
> Apr 27 14:56:09 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 7 consecutive times
> Apr 27 14:56:12 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 8 consecutive times
> Apr 27 14:56:15 DistroKit ModemManager[416]: <warn> [modem2] port ttyAT2
> timed out 9 consecutive times
> Apr 27 14:56:18 DistroKit ModemManager[416]: <warn> [modem2/bearer0] couldn't
> initialize context: Serial command timed out
> Apr 27 14:56:18 DistroKit ModemManager[416]: <warn> [modem2/bearer0]
> connection attempt #2 failed: Serial command timed out
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2] state changed
> (connecting -> registered)
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2/bearer0]
> connection #2 finished: duration 0s, tx: 0 bytes, rx :0 bytes
> Apr 27 14:56:18 DistroKit ModemManager[416]: <error> [modem2] port ttyAT2
> timed out 10 consecutive times, marking modem as invalid
Yes, after 10 consecutive timeouts we mark the modem as invalid. And
this is actually very important in your usecase, because we have no
way to detect when the modem is no longer there in the pure RS232 line
(i.e. the TTY always exists in the system even if there is no modem at
the other end of the TX/RX lines).
What happened here is, I think, that the modem is in data mode and
we're trying to send commands to it, and I don't know how much of that
is due to your initial test with --simple-connect.
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2] simple connect
> started...
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (4/8): wait to get fully enabled
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (5/8): register
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (6/8): bearer
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2] simple connect
> state (7/8): connect
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2] state changed
> (registered -> connecting)
> Apr 27 14:56:18 DistroKit ModemManager[416]: <warn> [modem2/bearer1]
> connection attempt #1 failed: Operation was cancelled
> Apr 27 14:56:18 DistroKit ModemManager[416]: <info> [modem2/bearer1]
> connection #1 finished: duration 0s, tx: 0 bytes, rx :0 bytes
> ```
>
> From my naïve understanding, commands and data stream have to be multiplexed
> over the same serial uart, right? Is it a problem of ModemManager or
> NetworkManager?
We don't support that multiplexing over the single UART :/ That's
called CMUX, and we never got around to supporting it in MM (it's
never too late!). In MM if you have one single TTY, you need to switch
that TTY between command and data modes, so while connected you won't
be able to send AT commands.
>
> I have not much experience with these kinds of devices, so each hint to
> proceed would be helpful. I can build and run MM and NM from source, even most
> recent master. I can provide debug logs. I would provide patches, but
> currently I don't even know where to start. O:-)
>
> Is there a way to get this modem running on Linux over that single UART at
> all?
Oh yes yes, this should be no problem. Also, make sure you have the
correct expected flow control settings configured via udev tags, not
sure if you did that.
--
Aleksander
https://aleksander.es
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