docs: Add docs for the nRF Cloud CoAP Client sample

WIP.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

doc/nrf/links.txt

@@ -772,6 +772,11 @@
 .. _`CoAP response codes`: https://datatracker.ietf.org/doc/html/rfc7252#section-12.1.2
 
 .. _`RFC 7252 - The Constrained Application Protocol`: https://datatracker.ietf.org/doc/html/rfc7252
+.. _`RFC 7959 - Block-Wise Transfer in CoAP`: https://datatracker.ietf.org/doc/html/rfc7959
+.. _`RFC 7049 - Concise Binary Object Representation`: https://datatracker.ietf.org/doc/html/rfc7049
+.. _`RFC 8610 - Concise Data Definition Language (CDDL)`: https://datatracker.ietf.org/doc/html/rfc8610
+.. _`RFC 8132 - PATCH and FETCH Methods for CoAP`: https://datatracker.ietf.org/doc/html/rfc8132
+.. _`RFC 9146 - Connection Identifier for DTLS 1.2`: https://datatracker.ietf.org/doc/html/rfc9146
 
 .. _`Content-Range requests (IETF RFC 7233)`: https://datatracker.ietf.org/doc/html/rfc7233
 

samples/cellular/nrf_cloud_coap_client/README.rst

@@ -0,0 +1,143 @@
+.. _nrf_cloud_coap_client_sample:
+
+nRF9160: nRF Cloud CoAP Client
+##############################
+
+.. contents::
+   :local:
+   :depth: 2
+
+The nRF Cloud CoAP Client sample demonstrates the communication between the nRF Cloud CoAP server and an nRF9160 SiP that acts as the CoAP client.
+
+The sample exercises all of the nRF Cloud services:
+
+* FOTA
+* Cellular location
+* A-GPS
+* P-GPS
+* Device messages
+
+Requirements
+************
+
+The sample supports the following development kit:
+
+.. table-from-rows:: /includes/sample_board_rows.txt
+   :header: heading
+   :rows: nrf9160dk_nrf9160_ns
+
+.. include:: /includes/tfm.txt
+
+Modem firmware version 1.3.5 or above is recommended, in order to benefit from the power savings provided by DTLS Connection ID
+
+Overview
+********
+
+The nRF Cloud CoAP Client sample performs the following actions:
+
+#. Connect to the nRF Cloud CoAP server.
+#. Gain authorization to use services by means of a JWT.
+#. Request a URL for P-GPS data, then download and store it.
+#. Periodically cycle through each service:
+
+   #. Check for a FOTA job.
+   #. Send a fake temperature reading.
+   #. Get device location using cellular and/or Wi-Fi data.
+   #. Send a GNSS PVT location.
+   #. Request A-GPS data (if needed), and inject into the modem.
+   #. Check for a shadow delta; if one received, acknowledge back to server.
+
+Configuration
+*************
+
+.. 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/nrf_cloud_coap_client`
+
+.. include:: /includes/build_and_run_ns.txt
+
+Provisioning device on nRF Cloud
+********************************
+
+For more information, see `nRF Cloud Utilities documentation`_.
+
+Only do the first step below once.
+
+  .. code-block:: console
+
+     python3 create_ca_cert.py -c US -st OR -l Portland -o "My Company" -ou "RD" -cn example.com -e admin@example.com -f CA
+     Creating self-signed CA certificate...
+     File created: CA0x3bc7f3b014a8ad492999c594f08bbc2fcffc5fd1_ca.pem
+     File created: CA0x3bc7f3b014a8ad492999c594f08bbc2fcffc5fd1_prv.pem
+     File created: CA0x3bc7f3b014a8ad492999c594f08bbc2fcffc5fd1_pub.pem
+
+     python3 device_credentials_installer.py --ca CA0x3bc7f3b014a8ad492999c594f08bbc2fcffc5fd1_ca.pem \
+     --ca_key CA0x3bc7f3b014a8ad492999c594f08bbc2fcffc5fd1_prv.pem --id_str nrf- --id_imei -s -d --coap
+     ...
+     <- OK
+     Saving provisioning endpoint CSV file provision.csv...
+     Provisioning CSV file saved
+
+Once the script creates the provision.csv file, visit http://nrfcloud.com/#/provision-devices to provision the device in nRF Cloud.
+
+Testing
+=======
+
+After programming the sample and all prerequisites to the development kit, test it by performing the following steps:
+
+1. Connect your nRF9160 DK to the PC using a USB cable and power on or reset your nRF9160 DK.
+#. Open a terminal emulator and observe that the following information is displayed:
+
+       The nRF Cloud CoAP client sample started
+#. Observe that the discovered IP address of the CoAP server is displayed on the terminal emulator.
+#. Observe that the nRF9160 DK sends periodic CoAP GET requests to the configured server for a configured resource after it gets LTE connection.
+#. Observe that the sample either displays the response data received from the server or indicates a timeout on the terminal.
+   For more information on the response codes, see `COAP response codes`_.
+
+
+
+Sample output
+=============
+
+The sample displays the data in the following format:
+
+.. code-block:: console
+
+   CoAP request sent: token 0x9772
+   CoAP response: code: 0x45, token 0x9772, payload: 15:39:40
+
+Instead of displaying every single CoAP frame content, the sample displays only the essential data.
+For the above sample output, the information displayed on the terminal conveys the following:
+
+* ``code:0x45`` -  CoAP response code (2.05 - Content), which is constant across responses
+* ``token 0x9772`` - CoAP token, which is unique per request/response pair
+* ``payload: 15:39:40`` - the actual message payload (current time in UTC format) from the resource that is queried in this sample
+
+References
+**********
+
+`RFC 7252 - The Constrained Application Protocol`_
+
+Dependencies
+************
+
+This sample uses the following |NCS| libraries:
+
+* :ref:`lte_lc_readme`
+
+It uses the following `sdk-nrfxlib`_ library:
+
+* :ref:`nrfxlib:nrf_modem`
+
+It uses the following Zephyr library:
+
+* :ref:`CoAP <zephyr:networking_api>`
+
+In addition, it uses the following secure firmware component:
+
+* :ref:`Trusted Firmware-M <ug_tfm>`