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  • Case ID: 343739
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nRF9160 SLM (Serial LTE modem) with Cellular: SLM Shell examples issues.

JackT

Hello everyone,

I am trying to test the SLM on the nRF9160DK on NCS 2.9.0. (SDK and toolchain)
I want to control the nRF9160 with an external MCU, so for this the application description of the SLM says:

"If you run your user application on an external MCU (for example, an nRF52 Series development kit), you can control the modem on an nRF91 Series device directly from the application. See the Cellular: SLM Shell for a sample implementation of such an application."

I have followed the .conf and .overlay steps, but i can not get it to work.
Here are the issues I am facing:

1. The SLM description says that hardware flow control has to be enabled while the SLM Shell says:
"The SLM application should be configured to use UART_2 on the nRF9160 side with no hardware flow control."

2. When using the nRF5340DK there is a note that says that the nRF9160 VDDIO (SW9) needs to be 3V.
But when doing this my nRF9160DK gets stuck printing only: <wrn> spi_nor: Waiting until flash is ready.
If I keep the switch at 1V8 i get the following output

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[00:00:00.254,943] <err> spi_nor: Device id f3 3c 1f does not match config c2 28 17
*** Booting nRF Connect SDK v2.9.0-7787b2649840 ***
*** Using Zephyr OS v3.7.99-1f8f3dc29142 ***
[00:00:00.272,247] <inf> at_cmd_custom: Custom AT commands enabled with 64 entries.
[00:00:00.280,426] <dbg> slm: main: RR: 0x00000001
[00:00:00.291,534] <inf> fs_nvs: 2 Sectors of 4096 bytes
[00:00:00.297,332] <inf> fs_nvs: alloc wra: 0, fe8
[00:00:00.302,612] <inf> fs_nvs: data wra: 0, 0
[00:00:00.543,457] <inf> slm: lib_modem init: 0
[00:00:00.548,492] <inf> mcuboot_util: Image index: 0, Swap type: none
[00:00:00.555,511] <inf> slm: Serial LTE Modem
[00:00:00.653,869] <inf> nrf_cloud_info: Device ID: 50525631-3738-4671-808a-1116e2648cee
[00:00:00.668,945] <inf> nrf_cloud_info: IMEI: 351901936411895
[00:00:00.764,495] <inf> nrf_cloud_info: UUID: 50525631-3738-4671-808a-1116e2648cee
[00:00:00.779,754] <inf> nrf_cloud_info: Modem FW: mfw_nrf9160_1.3.4
[00:00:00.786,682] <inf> nrf_cloud_info: Protocol: MQTT
[00:00:00.793,212] <inf> nrf_cloud_info: Download protocol: HTTPS
[00:00:00.799,835] <inf> nrf_cloud_info: Sec tag: 16842753
[00:00:00.806,701] <inf> nrf_cloud_info: Host name: mqtt.nrfcloud.com
[00:00:00.814,514] <inf> slm_uart_handler: UART baud: 115200 d/p/s-bits: 3/0/1 HWFC: 1
[00:00:00.823,089] <dbg> slm_at_host: slm_at_send_indicate: TX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

So now the spi_nor throws an error but the device does continue to boot.
If after it has booted, I turn on the nRF5340DK i can send the SLM commands and get a response.
But when the nRF9160 loses power, and now the 3V of the nRF53 is dominant, it goes back to waiting for the flash warning when starting up.

3. I have tried using the nRF7002DK because this one should run on 1V8 VDDIO.
But this keeps spamming:

--- 11 messages dropped ---
[00:00:40.689,544] <wrn> mdm_slm: RX_STOPPED (4)
[00:00:40.689,544] <wrn> mdm_slm: RX_STOPPED (8)

At this point, I am out of ideas on what it could be. I have tried hardware flow control on and off on all configurations.
I have tried with NCS 2.9.0 and 2.8.0. Using the default where you send command via PC works fine.

I hope someone can help with this.
Thanks in advance.

Kind regards,

Jack

  • 0

    Hello, 

    I've been assigned your ticket and will help you with this issue. How have you connected the nRF9160DK and the nRF5340DK, could you please elaborate?

    Thank you.

    Kind regards,
    Øyvind

  • 0 in reply to Øyvind

    the nRF9160DK and nRF5340DK are connected using the pin headers and dupont wires. For the connections i followed the Cellular: SLM Shell description so that is:


    Same when I tried the nRF7002DK:

  • 0 in reply to JackT

    Hi,

    If there are external flash issues and you don't need it, can you disable the external flash (see here for relevant Kconfig and devicetree configurations, but disable/remove instead). Are you able to proceeed with 3V in that case?

    The "mdm_slm: RX_STOPPED" error indicate UART communicatino problems. The voltage needs to be the same on both devices, and the nRF52 DKs only support 3V. But for other combinations, it does not matter as long as it is the same. Also, make sure flow control is disabled on both devices.

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