Nordic nRF91
The nRF91 series of chips from Nordic Semiconductor are based around an ARM Cortex-M33 core with integrated LTE-M/NB-IoT modem and GNSS.
Modem Support
Modem is supported in the nRF91 using Nordic’s Modem library.
Tool Issues
OpenOCD
There is no official support for Nordic Cortex M33 chips (nRF9160 or nRF5340).
Segger J-Link
To start the GDB servers for the application core, use these commands:
JLinkGDBServer -device nRF9160 -if SWD -speed 4000 -port 2331
Then you can connect GDB to targets:
(gdb) target remote localhost:2331