AT Monitor¶

Overview¶

The AT monitor sample demonstrates how to use the AT monitor library and define AT monitors to receive AT notifications from the Modem library.

The sample defines two AT monitors, one for network status notifications (+CEREG) and one for received signal quality parameters notifications (+CESQ) through the AT_MONITOR() macro. The sample then subscribes to both notifications and switches the modem to function mode one to register to the network. While the device is registering to the network, the sample uses one of the AT monitors to determine if the registration is complete and monitors the signal quality using the other monitor. Once the device registers with the network, the sample reads the modem PSM mode status, enables it, and reads the PSM mode status again.

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¶

Insert the nano-SIM card into the nano-SIM card slot.
Attach the U.FL cabled LTE-M/NB-IoT/NR+ Flexible Antenna.
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 Monitor sample on the command line.

Open a terminal window.
Go to NCS-Project/nrf9151-connectkit repository cloned in the Getting Started Guide.
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_monitor
```
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).
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:

Open up a serial terminal, specifying the correct serial port that your computer uses to communicate with the nRF9151 SiP:
WindowsmacOSUbuntu
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
Press the DFU/RST button to reset the nRF9151 SiP.

Observe the output of the terminal. You should see the output, similar to what is shown in the following:

Terminal

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 ***
AT Monitor sample started
Subscribing to notifications
Connecting to network
Resuming link quality monitor for AT notifications
Waiting for network
Link quality: -73 dBm
Network registration status: searching
Network registration status: home
Network connection ready
Pausing link quality monitor for AT notifications
Reading PSM info...
  PSM: enabled
  Periodic TAU string: 00000110
  Active time string: 00100001
Enabling PSM
Reading PSM info...
  PSM: enabled
  Periodic TAU string: 00000110
  Active time string: 00100001
Modem response:
+CEREG: 1,1
OK
Shutting down modem
Network registration status: no network
Bye