NRF5340 simulated boards (BabbleSim)
Overview
To allow simulating nrf5340 SOCs two Zephyr target boards are provided: the
nrf5340bsim/nrf5340/cpuapp and nrf5340bsim/nrf5340/cpunet.
These use BabbleSim to simulate the radio activity, and the POSIX architecture and the native simulator to run applications natively on the development system. This has the benefit of providing native code execution performance and easy debugging using native tools, but inherits its limitations.
Just like for the nrf5340dk targets, the nrf5340bsim/nrf5340/cpuapp build target provides support for the application core, and the nrf5340bsim/nrf5340/cpunet build target provides support for the network core on the simulated nRF5340 SOC.
These boards include models of some of the nRF5340 SOC peripherals:
AAR (Accelerated Address Resolver)
AES CCM & AES ECB encryption HW
CLOCK (Clock control)
DPPI (Distributed Programmable Peripheral Interconnect)
EGU (Event Generator Unit)
FICR (Factory Information Configuration Registers)
IPC (Interprocessor communication)
MUTEX (Mutual exclusive peripheral)
NVMC (Non-Volatile Memory Controller / Flash)
RADIO
RNG (Random Number Generator)
RTC (Real Time Counter)
TEMP (Temperature sensor)
TIMER
UICR (User Information Configuration Registers)
and will use the same drivers as the nrf5340dk targets for these. For more information on what is modelled to which level of detail, check the HW models implementation status.
Note that unlike a real nrf5340 device, the nrf5340bsim boards have unlimited RAM and flash for code.
Building for, and using these boards
If you are interested in developing on only one of the MCUs in this SOC, you can use the corresponding simulated target, nrf5340bsim/nrf5340/cpuapp or nrf5340bsim/nrf5340/cpunet following the instructions from the nrf52_bsim board. Simply change the board/target appropriately when building.
Note
Unlike in real HW, the net core MCU is set-up to automatically boot at start, to facilitate
developing without an image in the application core. You can control
this with either CONFIG_NATIVE_SIMULATOR_AUTOSTART_MCU, or the command line
option --cpu1_autostart.
If an MCU is booted without any image, it will automatically set itself to sleep.
Assembling both MCUs images into a single executable
By default, when you build targeting either nrf5340bsim/nrf5340/cpuapp or
nrf5340bsim/nrf5340/cpunet you will end up with a library (zephyr/zephyr.elf) that corresponds
to that MCU code image, and an executable (zephyr/zephyr.exe) that includes the native simulator
runner, SOC HW models, that image, and an empty image for the other MCU.
If you want to assemble an executable including a previously built image for the other MCU,
built with either Zephyr’s build system or another native simulator compatible build system,
you can provide that image to the Zephyr build of the second image using
CONFIG_NATIVE_SIMULATOR_EXTRA_IMAGE_PATHS.
You can also use System build (sysbuild) to build your dual MCU executable. The best way to understand how, may be to look into how this is done in one of the examples in the tree. For example, for the nrf53_sync_rtc sample, samples/boards/nordic/nrf53_sync_rtc/sysbuild.cmake.
Note
These libraries/images are not embedded images. You cannot use them for embedded devices, and cannot use an embedded image to assemble a native executable.
TrustZone, TF-M and other security considerations
ARM’s TrustZone is not modelled in these boards. This means that:
There is no differentiation between secure and non secure execution states or bus accesses.
All RAM, flash and peripherals are in principle accessible from all SW. Peripherals with their own interconnect master ports can, in principle, access any other peripheral or RAM area.
There is no nrf5340bsim/nrf5340/cpuapp/ns board/build target, or posibility of mixing secure and non-secure images.
Currently there is no model of the SPU, and therefore neither flash, RAM areas or peripherals can be labelled as restricted for secure or non secure access.
TF-M cannot be used.
Note that the ARM cryptocell-312 peripheral is not modelled. The mbedTLS library can still be used but with a SW crypto backend instead of the cryptocell HW acceleration.