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AT Client

Overview

The AT Client sample demonstrates the asynchronous serial communication taking place over UART to the nRF9151 modem. It acts as a proxy for sending directives to the modem using AT commands. This facilitates the reading of responses or analyzing of events related to the modem.

For more information on the AT commands, see the nRF91x1 AT Commands Reference Guide.

Requirements

Before you start, check that you have the required hardware and software:

  • 1x nRF9151 Connect Kit
  • 1x nano-SIM card with LTE-M or NB-IoT support
  • 1x U.FL cabled LTE-M/NB-IoT/NR+ Flexible Antenna (included in the box)
  • 1x USB-C Cable
  • A computer running macOS, Ubuntu, or Windows 10 or newer

Set up your board

  1. Insert the nano-SIM card into the nano-SIM card slot.
  2. Attach the U.FL cabled LTE-M/NB-IoT/NR+ Flexible Antenna.
  3. Connect the nRF9151 Connect Kit to the computer with a USB-C cable.

Building the sample

To build the sample, follow the instructions in Getting Started Guide to set up your preferred building environment.

Use the following steps to build the AT Client sample on the command line.

  1. Open a terminal window.

  2. Go to NCS-Project/nrf9151-connectkit repository cloned in the Getting Started Guide.

  3. Build the sample using the west build command, specifying the board (following the -b option) as nrf9151_connectkit/nrf9151/ns.

    west build -p always -b nrf9151_connectkit/nrf9151/ns samples/at_client

    The -p always option forces a pristine build, and is recommended for new users. Users may also use the -p auto option, which will use heuristics to determine if a pristine build is required, such as when building another sample.

    Note

    This sample has Cortex-M Security Extensions (CMSE) enabled and separates the firmware between Non-Secure Processing Environment (NSPE) and Secure Processing Environment (SPE). Because of this, it automatically includes the Trusted Firmware-M (TF-M).

  4. After building the sample successfully, the firmware with the name merged.hex can be found in the build directory.

Flashing the firmware

Set up your board before flashing the firmware. You can flash the sample using west flash:

west flash

Tip

In case you wonder, the west flash will execute the following command:

pyocd load --target nrf91 --frequency 4000000 build/merged.hex

Testing

After programming the sample, test it by performing the following steps:

  1. Open up a serial terminal, specifying the correct serial port that your computer uses to communicate with the nRF9151 SiP:

    1. Start PuTTY.

    2. Configure the correct serial port and click Open:

    Open up a terminal and run:

    screen <serial-port-name> 115200

    Open up a terminal and run:

    screen <serial-port-name> 115200

  2. Press the DFU/RST button to reset the nRF9151 SiP.

  3. Once the sample starts running, you should see the following output:

    Terminal
    1
2
3
4
5
6
7
    All pins have been configured as non-secure
Booting TF-M v2.1.0
[Sec Thread] Secure image initializing!
*** Booting nRF Connect SDK v2.9.99-98a5e50b9ac1 ***
*** Using Zephyr OS v3.7.99-693769a5c735 ***
The AT host sample started
Ready

  4. Test the following commands from the terminal:

    1
    AT+CGMI # (1)!
    1. This command retrieves the manufacturer identification.
      Terminal
      1
2
      Nordic Semiconductor ASA
OK

    2
    AT+CGMM # (1)!
    1. This command retrieves the System in Package (SiP) model identification.
      Terminal
      1
2
      nRF9151-LACA
OK

    3
    AT+CGMR # (1)!
    1. This command retrieves the modem firmware revision identification.
      Terminal
      1
2
      mfw_nrf91x1_2.0.2
OK

    4
    AT+CGSN=1 # (1)!
    1. This command retrieves the IMEI.
      Terminal
      1
2
      +CGSN: "35940423XXXXXXX"
OK

    5
    AT+CFUN? # (1)!

    1. This command reads the current functional mode.

      Terminal
      1
2
      +CFUN: <fun>
OK

      The read response parameter and its defined value are the following:

      <fun>

      • 0 – Minimum functionality mode. RF circuits are disabled by deactivating LTE and GNSS services.
      • 1 – Normal mode. The active mode is either LTE or GNSS, or both. Full functional mode. Active modes depend on %XSYSTEMMODE setting.
      • 2 – Receive only mode in active system mode. Active modes depend on %XSYSTEMMODE setting.
      • 4 – Flight mode. RF circuits are disabled by deactivating LTE and GNSS services.
      • 21 – LTE is activated.
      • 31 – GNSS is activated.
      • 41 – UICC is activated.
    6
    AT+CFUN=1 # (1)!
    1. This command sets the functional mode of the modem to normal.
      Terminal
      OK

    7
    AT+CIMI # (1)!
    1. This command reads the IMSI from the SIM card.
      Terminal
      1
2
      4600446364XXXXX
OK

Tip

You can refer to the nRF91x1 AT Commands Reference Guide to test more AT commands.