Could not send AT command, error: -8

[Remco]

I am trying to connect the DK to AWS.

I got the AT example working and uploaded the certificates. I managed to update the prj.conf file (and then took quite some time to realize that that file is only re-read when opening the example), to configure the project.

When i upload the hex file, it gets stuck in a loop:

*** Booting Zephyr OS build v2.3.0-rc1-ncs1  ***

MQTT AWS Jobs FOTA Sample, version: v1.0.0

Initializing bsdlib

Initialized bsdlib

LTE Link Connecting ...

E: Could not send AT command, error: -8

E: Could not set system mode, error: -8

ASSERTION FAIL [err == 0] @ ../src/main.c:563

LTE link could not be established.

E: r0/a1:  0x00000004  r1/a2:  0x00000233  r2/a3:  0x00000000

E: r3/a4:  0x00037d0e r12/ip:  0x20022f1c r14/lr:  0x0001e8f9

E:  xpsr:  0x61000000

E: s[ 0]:  0x00000001  s[ 1]:  0x00000001  s[ 2]:  0x00000001  s[ 3]:  0x00000001

E: s[ 4]:  0x00000001  s[ 5]:  0x00000001  s[ 6]:  0x00000001  s[ 7]:  0x00000001

E: s[ 8]:  0x00000001  s[ 9]:  0x00000001  s[10]:  0x00000001  s[11]:  0x00000001

E: s[12]:  0x00000001  s[13]:  0x00000001  s[14]:  0x00000001  s[15]:  0x00000001

E: fpscr:  0x00000000

E: Faulting instruction address (r15/pc): 0x0003331e

E: >>> ZEPHYR FATAL ERROR 4: Kernel panic on CPU 0

E: Current thread: 0x20023174 (unknown)

E: Resetting system

Any idea?

[Simon]

This line: "Could not send AT command, error: -8" implies that ncs\v1.3.0\nrf\lib\lte_link_control\lte_lc.c-->lte_lc_system_mode_set() fails. Thus the call to XSYSTEMMODE fails. Check out the information about this command in the infocenter:

"Note: Only one supported LTE mode allowed at a time. This command is allowed only before activating the modem using the CFUN=1 command. If the mode needs to be changed, the modem must first be set to flight mode using the CFUN=4 command."

Could you try to set the modem to flight mode first and see if that resolves your issues?

Best regards,

Simon

[Remco]

I have flashed the 'at_client' firmware back again. 'AT+CFUN?' works -> '+CFUN: 0'. 
"AT+CFUN=1' does not: -> 'ERROR'
'AT+CFUN=4' crashes the controller. i get no reply and no further commands work until i press the reset button.

I think this has always been the case, but i didnt notice the error before, since uploading the certificates worked.

May be the board is defect? it is revision 0.9.0, fresh from Farnell.

[Simon]

That is strange. Could you try to update the modem firmware to the latest and see if you're still experiencing this. Download the modem firmware from here.

Best regards,

Simon