NB-IoT, serial to UBLOX has a misterious bahaviour

NB-IoT
1

Using a Arduino Leonardo I can not get the serial connection with the UBLOX operational.
I use the nbIoT example with the following results:

  • when I recompile and upload the nbIoT sketch and the serial monitor on I see the following on the serial monitor:
    ⸮⸮⸮
    REBOOT_CAUSE_UNKNOWN
    Neul
    OK

When I try to connect with: AT+NCONFIG?
I see the line repatead in the receive window.
The same with other commands.

There is some connection between the Leonardo and the NB-IoT shiled as I can control the LED on pin 13.

Please advice.

Jan

2

Hi Jan,

Getting repeated messages (echo’s) in the Serial Monitor can usually indicate that the Serial wasn’t set correctly. However, you are getting messages from the module, so this is clearly not the case.

Have you also tried it with different Arduino’s? Or could you somehow confirm that the Serial1 of the Leonardo is working correctly (perhaps with a USB-to-Serial converter)?

Have you also been able to read the sensors without any issue?

3

Hi Gregory,

I just tested the Leonardo serial connection with an USB/RS232 converter and notices it operates as expected.
When I add the NB-IoT board and monitor the RS232 traffic (realterm) I see after a reset the UBLOX notification:
REBOOT_CAUSE_UNKNOWN
Neul
OK

When I monitor the Tx line from the Leonardo I see the command (AT+NCONFIG?) sent to the board but I seen no response from the UBLOX module, neither in the Serial Monitor or on my realterm monitor.

Can there be a serial communication malfunction on the IoT board?

4

Hi Jan,

I have send you rma information by email.

Regards,
Jan

5

Hi, I have the same problem with the same boards (Leonardo). Do you know wich it´s the solution?
Please can you confirm me that the uart pins should be cross connected, ie. NB-IoTt shield Tx –> Arduino Rx and NB-IoTshield Rx –> Arduino Tx.
Thanks in advance.

David Liras

6

I also have the same problem with the NB-IoT Deluxe (kickstarter) on a Crowduino M0. Messages are repeated in the Serial Monitor with no response, on recompile/upload get the same response as noted by above [quote=“jawove, post:1, topic:967”]
⸮⸮⸮
REBOOT_CAUSE_UNKNOWN
Neul
OK
[/quote]

did anyone solve this issue ? Is this a problem with the shield ?

Thanks in advance
Lorna

7

It appears that you have to select CR and LF in the serial monitor otherwise the commands are not recognised by the ublox module.

8

Hello,
I am continuing this post because I have the same problem but I see no answer on that:
in any AT cmd I send to the module, it always reboots & respones with:
"
î[00]ÒÊî[00]
REBOOT_CAUSE_UNKNOWN
Neul
OK
"
I am using a FTDI usb-to-serial board at 3.3V.
Did any of you facing the same problem resolve this? Does support team have any suggestions?
Could it be a power issue?
What are the min-max voltage values in Tx/Rx/Vcc pins that your shied can work?
Thank you in advance.

9

Resolved,
looking closely to shields schematics I saw that I need to set “D7” din HIGH (Enable pin) for the module to work properly (can be also attached directly to 3.3V for continuous operation) ! I post this to help anyone else facing the same problem.
:wink:

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