nRF9160 custom board cannot register to network

Hi,

My name is Alexandre and I am currently working on a GNSS tracker project.

I want to use the nRF9160 to connect to LTE-M network only and I am using an external GNSS for tracking.

I started on a devkit with the SLM app and everything works fine, I can connect and register to the network and send HTTP requests using LTE monitor.

Now I am switching to my custom board using the same SIM where the nRF9160 is used as a modem only component controlled by an ESP32 and I cannot register to the network.

You can the log file attached. I tried to replicate the same AT command sequence as the LTE monitor with "automatic requests" enabled.

The problem could come from the hardware as this is the first version of the board and antenna impedance has not be matched yet (only 0R resistor between MCU and antenna). You can find attached an extract of the schematic.

But it could also come from the software as I am not yet really familiar with nRF Connect SDK and Zephyr (Github link to project)


I really don't know where to start searching in order to identify the root cause of the issue.

Any help or advise would be appreciated. Thanks.

Regards

3005.custom_nRF9160_board_schematic.pdf

[15:39:02] >>> AT
[15:39:03] <<< OK

[15:39:20] >>> AT%XSYSTEMMODE=1,0,0,1
[15:39:21] <<< OK

[15:39:26] >>> AT+CFUN?
[15:39:26] <<< +CFUN: 0
[15:39:26] <<< OK

[15:39:38] >>> AT+CGSN=1
[15:39:38] <<< +CGSN: "351358814861545"
[15:39:38] <<< OK

[15:39:41] >>> AT+CGMI
[15:39:42] <<< Nordic Semiconductor ASA
[15:39:42] <<< OK

[15:39:46] >>> AT+CGMM
[15:39:46] <<< nRF9160-SICA
[15:39:46] <<< OK

[15:39:49] >>> AT+CGMR
[15:39:50] <<< mfw_nrf9160_1.2.0
[15:39:50] <<< OK

[15:39:54] >>> AT+CEMODE?
[15:39:54] <<< +CEMODE: 2
[15:39:54] <<< OK

[15:39:58] >>> AT%XCBAND=?
[15:39:58] <<< %XCBAND: (1,2,3,4,5,8,12,13,17,18,19,20,25,26,28,66)
[15:39:58] <<< OK

[15:40:04] >>> AT+CMEE?
[15:40:04] <<< +CMEE: 0
[15:40:04] <<< OK

[15:40:07] >>> AT+CMEE=1
[15:40:08] <<< OK

[15:40:13] >>> AT+CNEC=24
[15:40:13] <<< OK

[15:40:19] >>> AT+CGEREP?
[15:40:19] <<< +CGEREP: 0,0
[15:40:19] <<< OK

[15:40:23] >>> AT+CGDCONT?
[15:40:24] <<< OK

[15:40:34] >>> AT+CGDCONT=0,"IP","hologram"
[15:40:35] <<< OK

[15:40:42] >>> AT+CGDCONT?
[15:40:42] <<< +CGDCONT: 0,"IP","hologram","",0,0
[15:40:42] <<< OK

[15:40:49] >>> AT+CGACT?
[15:40:50] <<< +CGACT: 0,0
[15:40:50] <<< OK

[15:40:58] >>> AT+CGEREP=1
[15:40:59] <<< OK

[15:41:02] >>> AT+CIND=1,1,1
[15:41:03] <<< OK

[15:41:07] >>> AT+CEREG=5
[15:41:07] <<< OK

[15:41:20] >>> AT%CESQ=1
[15:41:20] <<< OK

[15:41:37] >>> AT+COPS=3,2
[15:41:38] <<< OK

[15:42:09] >>> AT+COPS?
[15:42:09] <<< +COPS: 0
[15:42:09] <<< OK

[15:42:18] >>> AT+CFUN=1
[15:42:21] <<< OK

[15:42:25] >>> AT+COPS?
[15:42:26] <<< +COPS: 0
[15:42:26] <<< OK

[15:42:41] >>> AT+CPIN?
[15:42:43] <<< +CPIN: READY
[15:42:43] <<< OK

[15:42:48] >>> AT+CPINR="SIM PIN"
[15:42:49] <<< +CPINR: "SIM PIN",3
[15:42:49] <<< OK

[15:42:57] >>> AT+CIMI
[15:42:57] <<< 234500007347745
[15:42:57] <<< OK

[15:43:23] <<< %CESQ: 26,1,20,2
[15:43:23] <<< +CEREG: 2,"C163","00005A06",7,0,0,"11100000","11100000"
[15:43:28] <<< %CESQ: 26,1,14,2

[15:43:35] >>> AT+COPS?
[15:43:36] <<< +COPS: 0
[15:43:36] <<< OK

[15:43:58] <<< +CEREG: 2,"FFFE","FFFFFFFF",7,0,0,"11100000","11100000"
[15:44:06] <<< +CEREG: 2,"0004","00BABE04",7,0,0,"11100000","11100000"
[15:44:10] <<< %CESQ: 21,1,14,2
[15:44:32] <<< +CEREG: 2,"FFFE","FFFFFFFF",7,0,0,"11100000","11100000"
[15:44:35] <<< %CESQ: 255,0,255,0
[15:44:52] <<< %CESQ: 9,0,0,0
[15:44:52] <<< +CEREG: 2,"0004","00999A04",7,0,0,"11100000","11100000"
[15:44:55] <<< %CESQ: 15,0,0,0
[15:44:56] <<< %CESQ: 15,0,5,0
[15:45:49] <<< %CESQ: 15,0,0,0
[15:45:58] <<< %CESQ: 15,0,5,0
[15:46:41] <<< %CESQ: 15,0,0,0
[15:46:50] <<< %CESQ: 15,0,5,0
[15:47:03] <<< %CESQ: 7,0,20,2
[15:47:04] <<< %CESQ: 14,0,3,0
[15:47:43] <<< %CESQ: 14,0,8,1
[15:48:14] <<< %CESQ: 14,0,2,0
[15:48:26] <<< %CESQ: 14,0,7,1
[15:48:39] <<< %CESQ: 14,0,2,0
[15:48:53] <<< %CESQ: 14,0,7,1
[15:49:25] <<< %CESQ: 14,0,2,0
[15:49:27] <<< %CESQ: 14,0,7,1
[15:50:35] <<< %CESQ: 19,0,13,1

  • Here is the update about this issue.

    • I updated the modem firmware but it did not help.
    • I tested closer to an antenna but it did not help
    • We tuned the antenna but it did not help

    Then we reviewed our electronic design and found an issue regarding the VDD_GPIO pin that was wired directly to VBATT (3.7V) instead of being connected to the 3V3 regulated voltage.

    We ordered a new PCB and soldered everything by hand (not without difficulties Sweat) the modem now registers to the network Tada

    It registers in a few seconds even indoors !

    So our problem was probably due to this design error and/or soldering issue.

    Thanks for your support.

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