.. _at_client_sample:

Cellular: AT Client
###################

.. contents::
   :local:
   :depth: 2

The AT Client sample demonstrates the asynchronous serial communication taking place over UART to the nRF91 Series modem.
The sample enables you to use an external computer or MCU to send AT commands to the LTE-M/NB-IoT modem of your nRF91 Series device.

Requirements
************

The sample supports the following development kits:

.. table-from-sample-yaml::

.. include:: /includes/tfm.txt

Overview
********

The AT Client sample acts as a proxy for sending directives to the nRF91 Series modem using AT commands.
This facilitates the reading of responses or analyzing of events related to the nRF91 Series modem.
You can initiate the commands manually from a terminal such as the `nRF Connect Serial Terminal`_, or visually using the `Cellular Monitor`_ app.
Both apps are part of `nRF Connect for Desktop`_.

For more information on the AT commands, see the `nRF91x1 AT Commands Reference Guide`_  or `nRF9160 AT Commands Reference Guide`_ depending on the SiP you are using.

.. include:: /libraries/modem/nrf_modem_lib/nrf_modem_lib_trace.rst
   :start-after: modem_lib_sending_traces_UART_start
   :end-before: modem_lib_sending_traces_UART_end

Building and running
********************

.. |sample path| replace:: :file:`samples/cellular/at_client`

.. include:: /includes/build_and_run_ns.txt


Testing
=======

After programming the sample to your development kit, test it by performing the following steps:

1. Press the reset button on the nRF91 Series DK to reboot the kit and start the AT Client sample.
#. :ref:`Connect to the nRF91 Series DK with nRF Connect Serial Terminal <serial_terminal_connect>`.
#. Run the following commands from the Serial Terminal:

   a. Enter the command: :command:`AT+CFUN?`.

      This command reads the current functional mode of the modem and triggers the command :command:`AT+CFUN=1` which sets the functional mode of the modem to normal.

   #. Enter the command: :command:`AT%XOPERID`.

      This command returns the network operator ID.

   #. Enter the command: :command:`AT%XMONITOR`.

      This command returns the modem parameters.

   #. Enter the command: :command:`AT%XTEMP?`.

      This command displays the current modem temperature.

   #. Enter the command: :command:`AT%CMNG=1`.

      This command displays a list of all certificates that are stored on your device.
      If you add the device to nRF Cloud, a CA certificate, a client certificate, and a private key with security tag 16842753 (which is the security tag for nRF Cloud credentials) are displayed.


Sample output
=============

Following is a sample output of the command :command:`AT%XMONITOR`:

.. code-block:: console

   AT%XMONITOR
   %XMONITOR: 5,"","","24201","76C1",7,20,"0102DA03",105,6400,53,24,"","11100000","11100000"
   OK


References
**********

* `nRF91x1 AT Commands Reference Guide`_
* `nRF9160 AT Commands Reference Guide`_

Dependencies
************

This sample uses the following |NCS| libraries:


* :ref:`lib_at_host` which includes:

  * :ref:`at_monitor_readme`

It uses the following `sdk-nrfxlib`_ library:

* :ref:`nrfxlib:nrf_modem`

In addition, it uses the following secure firmware component:

* :ref:`Trusted Firmware-M <ug_tfm>`